Experimenting

.github/actions/code-sign/action.yml

@@ -1,113 +0,0 @@
-name: Code-sign Windows binaries
-description: >
-  Sign every .exe under a given path in place via the DefinedNet code-signer
-  Lambda. If `role` or `bucket` is empty, logs a notice and skips signing so
-  forks and dev branches without AWS access still produce usable builds.
-
-inputs:
-  path:
-    description: "Directory whose .exe files should be signed in place"
-    required: true
-  role:
-    description: "IAM role ARN to assume via OIDC; empty disables signing"
-    required: false
-    default: ""
-  bucket:
-    description: "S3 staging bucket the code-signer Lambda reads from; empty disables signing"
-    required: false
-    default: ""
-  region:
-    description: "AWS region for the role and Lambda"
-    required: false
-    default: "us-east-2"
-  function-name:
-    description: "Code-signer Lambda function name"
-    required: false
-    default: "code-signer"
-  key-prefix:
-    description: "S3 key prefix the caller is authorized to write under"
-    required: false
-    default: "code-signing/slackhq/nebula"
-
-runs:
-  using: composite
-  steps:
-    - name: Skip notice
-      if: inputs.role == '' || inputs.bucket == ''
-      shell: sh
-      run: echo "::notice::code-signer role or bucket not set; skipping code signing."
-
-    - name: Configure AWS credentials
-      if: inputs.role != '' && inputs.bucket != ''
-      uses: aws-actions/configure-aws-credentials@v6
-      with:
-        role-to-assume: ${{ inputs.role }}
-        aws-region: ${{ inputs.region }}
-        # Default is 12 retries to ride out IAM trust-policy propagation; once
-        # the role is stable we want a real misconfiguration to fail fast.
-        retry-max-attempts: 5
-
-    - name: Sign .exe files
-      if: inputs.role != '' && inputs.bucket != ''
-      shell: sh
-      env:
-        SIGN_PATH: ${{ inputs.path }}
-        BUCKET: ${{ inputs.bucket }}
-        FUNCTION_NAME: ${{ inputs.function-name }}
-        KEY_PREFIX: ${{ inputs.key-prefix }}
-      run: |
-        set -eu
-        RUN="${GITHUB_RUN_ID}-${GITHUB_RUN_ATTEMPT}"
-
-        find "$SIGN_PATH" -name '*.exe' -print | while read -r path
-        do
-            rel=${path#"$SIGN_PATH"/}
-            file=$(basename "$path")
-            name=${file%.exe}
-            prefix="${KEY_PREFIX}/${RUN}"
-            src="${prefix}/unsigned/${rel}"
-            dst="${prefix}/signed/${rel}"
-
-            echo "::group::Sign ${rel}"
-            echo "Uploading unsigned to s3://${BUCKET}/${src}"
-            aws s3 cp --no-progress "$path" "s3://${BUCKET}/${src}" >/dev/null
-
-            echo "Invoking ${FUNCTION_NAME} Lambda"
-            payload=$(jq -nc \
-                --arg s "$src" \
-                --arg d "$dst" \
-                --arg p "$name" \
-                '{source_key: $s, dest_key: $d, program_name: $p}')
-            meta=$(aws lambda invoke \
-                --function-name "$FUNCTION_NAME" \
-                --cli-binary-format raw-in-base64-out \
-                --payload "$payload" \
-                --output json \
-                /tmp/sign-resp.json)
-            if echo "$meta" | jq -e '.FunctionError != null' >/dev/null
-            then
-                echo "::endgroup::"
-                echo "::error::code-signer Lambda failed for ${rel}"
-                cat /tmp/sign-resp.json >&2
-                exit 1
-            fi
-
-            echo "Downloading signed back to ${path}"
-            aws s3 cp --no-progress "s3://${BUCKET}/${dst}" "$path" >/dev/null
-
-            aws s3 rm "s3://${BUCKET}/${src}" >/dev/null 2>&1 || true
-            aws s3 rm "s3://${BUCKET}/${dst}" >/dev/null 2>&1 || true
-
-            # Sanity-check the bytes we got back actually carry an Authenticode
-            # signature that this machine can validate end to end.
-            status=$(powershell -NoProfile -Command "(Get-AuthenticodeSignature -FilePath '$path').Status" | tr -d '\r')
-            if [ "$status" != "Valid" ]
-            then
-                echo "::endgroup::"
-                echo "::error::${rel} signature status: ${status} (expected Valid)"
-                exit 1
-            fi
-
-            echo "Signed ${rel} (sha256=$(jq -r '.sha256' /tmp/sign-resp.json), status=${status})"
-            echo "::endgroup::"
-        done

.github/workflows/release.yml

@@ -24,7 +24,7 @@ jobs:
           mv build/*.tar.gz release
 
       - name: Upload artifacts
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@v6
         with:
           name: linux-latest
           path: release
@@ -32,9 +32,6 @@ jobs:
   build-windows:
     name: Build Windows
     runs-on: windows-latest
-    permissions:
-      id-token: write
-      contents: read
     steps:
       - uses: actions/checkout@v6
 
@@ -57,15 +54,8 @@ jobs:
           mkdir build\dist\windows
           mv dist\windows\wintun build\dist\windows\
 
-      - name: Code-sign
-        uses: ./.github/actions/code-sign
-        with:
-          path: build
-          role: ${{ secrets.DEFINED_CODE_SIGNER_ROLE }}
-          bucket: ${{ secrets.DEFINED_CODE_SIGNER_BUCKET }}
-
       - name: Upload artifacts
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@v6
         with:
           name: windows-latest
           path: build
@@ -85,7 +75,7 @@ jobs:
 
       - name: Import certificates
         if: env.HAS_SIGNING_CREDS == 'true'
-        uses: Apple-Actions/import-codesign-certs@v7
+        uses: Apple-Actions/import-codesign-certs@v6
         with:
           p12-file-base64: ${{ secrets.APPLE_DEVELOPER_CERTIFICATE_P12_BASE64 }}
           p12-password: ${{ secrets.APPLE_DEVELOPER_CERTIFICATE_PASSWORD }}
@@ -114,7 +104,7 @@ jobs:
           fi
 
       - name: Upload artifacts
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@v6
         with:
           name: darwin-latest
           path: ./release/*
@@ -138,21 +128,21 @@ jobs:
 
       - name: Download artifacts
         if: ${{ env.HAS_DOCKER_CREDS == 'true' }}
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@v7
         with:
           name: linux-latest
           path: artifacts
 
       - name: Login to Docker Hub
         if: ${{ env.HAS_DOCKER_CREDS == 'true' }}
-        uses: docker/login-action@v4
+        uses: docker/login-action@v3
         with:
           username: ${{ vars.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Set up Docker Buildx
         if: ${{ env.HAS_DOCKER_CREDS == 'true' }}
-        uses: docker/setup-buildx-action@v4
+        uses: docker/setup-buildx-action@v3
 
       - name: Build and push images
         if: ${{ env.HAS_DOCKER_CREDS == 'true' }}
@@ -173,7 +163,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Download artifacts
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@v7
         with:
           path: artifacts
 

.github/workflows/smoke-extra.yml

@@ -14,18 +14,10 @@ on:
       - 'go.sum'
 jobs:
 
-  smoke-extra-libvirt:
+  smoke-extra:
     if: github.ref == 'refs/heads/master' || contains(github.event.pull_request.labels.*.name, 'smoke-test-extra')
-    name: ${{ matrix.target }}
+    name: Run extra smoke tests
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        target:
-          - freebsd-amd64
-          - openbsd-amd64
-          - netbsd-amd64
-          - linux-amd64-ipv6disable
     env:
       VAGRANT_DEFAULT_PROVIDER: libvirt
     steps:
@@ -48,85 +40,28 @@ jobs:
         sudo chmod 666 /var/run/libvirt/libvirt-sock
         vagrant plugin install vagrant-libvirt
 
-    - name: ${{ matrix.target }}
-      run: make smoke-vagrant/${{ matrix.target }}
+    - name: freebsd-amd64
+      run: make smoke-vagrant/freebsd-amd64
 
-    timeout-minutes: 30
+    - name: openbsd-amd64
+      run: make smoke-vagrant/openbsd-amd64
 
-  # linux-386 needs VirtualBox, which conflicts with KVM/libvirt -- isolated job.
-  smoke-extra-virtualbox:
-    if: github.ref == 'refs/heads/master' || contains(github.event.pull_request.labels.*.name, 'smoke-test-extra')
-    name: linux-386
-    runs-on: ubuntu-latest
-    env:
-      VAGRANT_DEFAULT_PROVIDER: virtualbox
-    steps:
+    - name: netbsd-amd64
+      run: make smoke-vagrant/netbsd-amd64
 
-    - uses: actions/checkout@v6
+    - name: linux-amd64-ipv6disable
+      run: make smoke-vagrant/linux-amd64-ipv6disable
 
-    - uses: actions/setup-go@v6
-      with:
-        go-version: '1.25'
-        check-latest: true
-
-    - name: add hashicorp source
-      run: wget -O- https://apt.releases.hashicorp.com/gpg | gpg --dearmor | sudo tee /usr/share/keyrings/hashicorp-archive-keyring.gpg && echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
-
-    - name: install vagrant and virtualbox
+    # linux-386 runs last because it requires disabling KVM to use VirtualBox,
+    # which prevents libvirt (used by the other tests) from working after this point.
+    - name: install virtualbox for i386 test
       run: |
-        sudo apt-get update && sudo apt-get install -y vagrant virtualbox
+        sudo apt-get install -y virtualbox
         sudo rmmod kvm_amd kvm_intel kvm 2>/dev/null || true
 
     - name: linux-386
+      env:
+        VAGRANT_DEFAULT_PROVIDER: virtualbox
       run: make smoke-vagrant/linux-386
 
     timeout-minutes: 30
-
-  smoke-windows:
-    if: github.ref == 'refs/heads/master' || contains(github.event.pull_request.labels.*.name, 'smoke-test-extra')
-    name: Run windows smoke test
-    runs-on: windows-latest
-    steps:
-
-    - uses: actions/checkout@v6
-
-    - uses: actions/setup-go@v6
-      with:
-        go-version: '1.25'
-        check-latest: true
-
-    # WSL2 + Ubuntu so the smoke can run a real linux peer with its own
-    # netns. iputils-ping is needed for the in-WSL ping check. WSL1 has no
-    # real kernel and would lack /dev/net/tun, so we have to force WSL2.
-    - uses: Vampire/setup-wsl@v3
-      with:
-        distribution: Ubuntu-24.04
-        additional-packages: iputils-ping iproute2
-
-    # Vampire/setup-wsl provisions WSL1 even when the WSL2 platform is present.
-    # Convert the distro to WSL2 explicitly before we try to use /dev/net/tun.
-    - name: convert distro to WSL2
-      shell: pwsh
-      run: |
-        wsl --set-version Ubuntu-24.04 2
-        wsl --shutdown
-        wsl --list --verbose
-
-    - name: build windows nebula
-      run: make bin-windows
-
-    - name: build linux nebula for WSL
-      shell: bash
-      env:
-        GOOS: linux
-        GOARCH: amd64
-      run: |
-        mkdir -p build/linux-amd64
-        go build -o build/linux-amd64/nebula ./cmd/nebula
-
-    - name: run smoke-windows
-      shell: pwsh
-      working-directory: ./.github/workflows/smoke
-      run: ./smoke-windows.ps1
-
-    timeout-minutes: 15

.github/workflows/smoke/smoke-windows.ps1

@@ -1,272 +0,0 @@
-#!/usr/bin/env pwsh
-# Windows smoke test for the nebula tun + UDP + NLM code paths.
-#
-# Topology:
-#   - lighthouse runs natively on the Windows host (wintun + windows UDP)
-#   - peer runs inside WSL2 (Linux build of nebula, /dev/net/tun)
-#
-# WSL2 gives us a real netns boundary so the loopback fast-path on Windows
-# does not short-circuit the overlay -- when WSL pings the lighthouse VPN IP,
-# Linux has no idea that IP is local to the Windows host, so the packet is
-# forced through nebula. Same in reverse.
-
-$ErrorActionPreference = 'Stop'
-
-# wsl.exe emits UTF-16 LE by default which PowerShell reads as bytes, mangling
-# every captured string. WSL_UTF8 makes wsl.exe emit UTF-8 instead.
-$env:WSL_UTF8 = '1'
-
-$RepoRoot = Resolve-Path "$PSScriptRoot\..\..\.."
-$Nebula = Join-Path $RepoRoot 'nebula.exe'
-$NebulaCert = Join-Path $RepoRoot 'nebula-cert.exe'
-$NebulaLinux = Join-Path $RepoRoot 'build\linux-amd64\nebula'
-
-if (-not (Test-Path $Nebula)) { throw "missing $Nebula; run 'make bin-windows' first" }
-if (-not (Test-Path $NebulaCert)) { throw "missing $NebulaCert; run 'make bin-windows' first" }
-if (-not (Test-Path $NebulaLinux)) { throw "missing $NebulaLinux; build the linux nebula first" }
-
-# Matches the distro installed by Vampire/setup-wsl in smoke-extra.yml.
-$Distro = 'Ubuntu-24.04'
-$listed = (wsl --list --quiet 2>$null) -join "`n"
-if ($listed -notmatch [regex]::Escape($Distro)) {
-    throw "WSL distro $Distro not registered. Got: $listed"
-}
-Write-Host "Using WSL distro: $Distro"
-
-# Windows host as seen from inside WSL: WSL's default-route gateway. We extract
-# it with a regex rather than awk fields so PowerShell does not eat any '$N'
-# tokens, and tabs/double-spaces in `ip route` output do not confuse a cut.
-$ipCmd = 'ip route show default | grep -oE "([0-9]+\.){3}[0-9]+" | head -1'
-$WindowsIp = (wsl -d $Distro -- bash -c $ipCmd).Trim()
-if (-not $WindowsIp) { throw "could not determine Windows host IP from WSL" }
-Write-Host "Windows host IP from WSL: $WindowsIp"
-
-$WorkDir = Join-Path $env:TEMP 'nebula-smoke-windows'
-if (Test-Path $WorkDir) { Remove-Item -Recurse -Force $WorkDir }
-New-Item -ItemType Directory -Path $WorkDir | Out-Null
-
-$WslDir = '/tmp/nebula-smoke'
-wsl -d $Distro -- bash -c "rm -rf $WslDir && mkdir -p $WslDir" | Out-Null
-
-$DevName = 'nebula-smoke'
-$Ip1 = '192.168.241.1'
-$Ip2 = '192.168.241.2'
-$Port = 4242
-
-& $NebulaCert ca -name 'smoke-ca' -out-crt "$WorkDir\ca.crt" -out-key "$WorkDir\ca.key"
-if ($LASTEXITCODE -ne 0) { throw "nebula-cert ca failed (exit $LASTEXITCODE)" }
-
-& $NebulaCert sign -name 'lighthouse' -networks "$Ip1/24" -ca-crt "$WorkDir\ca.crt" -ca-key "$WorkDir\ca.key" -out-crt "$WorkDir\lighthouse.crt" -out-key "$WorkDir\lighthouse.key"
-if ($LASTEXITCODE -ne 0) { throw "nebula-cert sign lighthouse failed (exit $LASTEXITCODE)" }
-
-& $NebulaCert sign -name 'peer' -networks "$Ip2/24" -ca-crt "$WorkDir\ca.crt" -ca-key "$WorkDir\ca.key" -out-crt "$WorkDir\peer.crt" -out-key "$WorkDir\peer.key"
-if ($LASTEXITCODE -ne 0) { throw "nebula-cert sign peer failed (exit $LASTEXITCODE)" }
-
-# Windows lighthouse config.
-@"
-pki:
-  ca: $WorkDir\ca.crt
-  cert: $WorkDir\lighthouse.crt
-  key: $WorkDir\lighthouse.key
-static_host_map: {}
-lighthouse:
-  am_lighthouse: true
-  interval: 60
-  hosts: []
-listen:
-  host: 0.0.0.0
-  port: $Port
-tun:
-  disabled: false
-  dev: $DevName
-  drop_local_broadcast: false
-  drop_multicast: false
-  tx_queue: 500
-  mtu: 1300
-  network_category: private
-logging:
-  level: info
-  format: text
-firewall:
-  outbound_action: drop
-  inbound_action: drop
-  conntrack:
-    tcp_timeout: 12m
-    udp_timeout: 3m
-    default_timeout: 10m
-  outbound:
-    - port: any
-      proto: any
-      host: any
-  inbound:
-    - port: any
-      proto: any
-      host: any
-"@ | Out-File -FilePath "$WorkDir\lighthouse.yml" -Encoding utf8
-
-# WSL peer config (paths are POSIX, deliberately).
-@"
-pki:
-  ca: $WslDir/ca.crt
-  cert: $WslDir/peer.crt
-  key: $WslDir/peer.key
-static_host_map:
-  "${Ip1}": ["${WindowsIp}:$Port"]
-lighthouse:
-  am_lighthouse: false
-  interval: 60
-  hosts:
-    - "${Ip1}"
-listen:
-  host: 0.0.0.0
-  port: 0
-tun:
-  disabled: false
-  dev: nebula1
-  drop_local_broadcast: false
-  drop_multicast: false
-  tx_queue: 500
-  mtu: 1300
-logging:
-  level: info
-  format: text
-firewall:
-  outbound_action: drop
-  inbound_action: drop
-  conntrack:
-    tcp_timeout: 12m
-    udp_timeout: 3m
-    default_timeout: 10m
-  outbound:
-    - port: any
-      proto: any
-      host: any
-  inbound:
-    - port: any
-      proto: any
-      host: any
-"@ | Out-File -FilePath "$WorkDir\peer.yml" -Encoding utf8
-
-# Stage WSL artifacts. Convert Windows paths to WSL paths ourselves rather than
-# calling `wslpath`, because PowerShell's argument-passing to external EXEs
-# strips backslashes from path arguments in ways that are hard to escape around.
-function ConvertTo-WslPath {
-    param([string]$WindowsPath)
-    if ($WindowsPath -notmatch '^([A-Za-z]):\\(.*)$') {
-        throw "cannot convert path to WSL: $WindowsPath"
-    }
-    return "/mnt/$($matches[1].ToLower())/$($matches[2].Replace('\','/'))"
-}
-
-$WslWorkDir = ConvertTo-WslPath $WorkDir
-$WslNebulaPath = ConvertTo-WslPath $NebulaLinux
-wsl -d $Distro -- bash -c "cp '$WslWorkDir/ca.crt' '$WslWorkDir/peer.crt' '$WslWorkDir/peer.key' '$WslWorkDir/peer.yml' $WslDir/ && cp '$WslNebulaPath' $WslDir/nebula && chmod +x $WslDir/nebula"
-
-# Make sure WSL has tun support and /dev/net/tun is usable before starting
-# nebula. Diagnostics first so a fail here points at the real problem (e.g.
-# WSL1 distros do not have a real kernel and will not have tun).
-Write-Host '=== WSL diagnostic ==='
-wsl --version 2>&1 | Out-Host
-wsl --list --verbose 2>&1 | Out-Host
-wsl -d $Distro -u root -- uname -a | Out-Host
-wsl -d $Distro -u root -- bash -c "modprobe tun 2>&1 || true; mkdir -p /dev/net; [ -c /dev/net/tun ] || mknod /dev/net/tun c 10 200; chmod 600 /dev/net/tun; ls -l /dev/net/tun"
-if ($LASTEXITCODE -ne 0) { throw "failed to prepare /dev/net/tun in WSL (TUN support missing?)" }
-
-# Deliberately no New-NetFirewallRule calls here -- nebula's windows_bypass_wdf
-# feature is supposed to install WFP permit filters that let inbound traffic
-# through Windows Defender Firewall on its own. If this smoke regresses, that
-# feature regressed.
-
-$lhOut = Join-Path $WorkDir 'lighthouse.out.log'
-$lhErr = Join-Path $WorkDir 'lighthouse.err.log'
-$lhProc = Start-Process -FilePath $Nebula -ArgumentList @('-config', "$WorkDir\lighthouse.yml") `
-    -PassThru -NoNewWindow `
-    -RedirectStandardOutput $lhOut `
-    -RedirectStandardError $lhErr
-
-# Run nebula in WSL as root with no sudo + no shell wrapper. PowerShell's
-# Start-Process arg quoting mangles `bash -c "..."` strings that contain
-# spaces/redirections, so we skip bash entirely and let Start-Process do the
-# stdout/stderr capture itself.
-$peerOut = Join-Path $WorkDir 'peer.out.log'
-$peerErr = Join-Path $WorkDir 'peer.err.log'
-$peerProc = Start-Process -FilePath 'wsl' `
-    -ArgumentList @('-d', $Distro, '-u', 'root', '--', "$WslDir/nebula", '-config', "$WslDir/peer.yml") `
-    -PassThru -NoNewWindow `
-    -RedirectStandardOutput $peerOut `
-    -RedirectStandardError $peerErr
-
-function Wait-Until {
-    param([scriptblock]$Predicate, [int]$TimeoutSec, [string]$What)
-    $deadline = (Get-Date).AddSeconds($TimeoutSec)
-    while ((Get-Date) -lt $deadline) {
-        if (& $Predicate) { return }
-        Start-Sleep -Milliseconds 500
-    }
-    throw "timed out waiting for: $What"
-}
-
-try {
-    Wait-Until -TimeoutSec 30 -What "windows wintun adapter $DevName with NetworkCategory=Private" -Predicate {
-        if ($lhProc.HasExited) { throw "lighthouse exited (code $($lhProc.ExitCode)) before tun was ready" }
-        $p = Get-NetConnectionProfile -InterfaceAlias $DevName -ErrorAction SilentlyContinue
-        $p -and ("$($p.NetworkCategory)" -ieq 'Private')
-    }
-    Write-Host "OK: $DevName NetworkCategory=Private"
-
-    Wait-Until -TimeoutSec 30 -What "WSL nebula1 with $Ip2" -Predicate {
-        if ($peerProc.HasExited) { throw "peer exited (code $($peerProc.ExitCode)) before tun was ready" }
-        $r = wsl -d $Distro -u root -- bash -c "ip -o addr show nebula1 2>/dev/null | grep -q 'inet $Ip2' && echo yes"
-        ("$r").Trim() -eq 'yes'
-    }
-    Write-Host "OK: WSL nebula1 has $Ip2"
-
-    Wait-Until -TimeoutSec 30 -What "ping from WSL peer to windows lighthouse ($Ip1)" -Predicate {
-        if ($peerProc.HasExited) { throw "peer exited (code $($peerProc.ExitCode)) before ping succeeded" }
-        $r = wsl -d $Distro -u root -- bash -c "ping -c1 -W1 $Ip1 >/dev/null 2>&1 && echo OK"
-        ("$r").Trim() -eq 'OK'
-    }
-    Write-Host "OK: WSL peer -> windows lighthouse"
-
-    Wait-Until -TimeoutSec 30 -What "ping from windows lighthouse to WSL peer ($Ip2)" -Predicate {
-        $null = & ping.exe -n 1 -w 1000 $Ip2
-        $LASTEXITCODE -eq 0
-    }
-    Write-Host "OK: windows lighthouse -> WSL peer"
-
-    Write-Host ''
-    Write-Host 'All smoke checks passed.'
-}
-catch {
-    Write-Host ''
-    Write-Host '=== lighthouse stdout ==='
-    Get-Content $lhOut -ErrorAction SilentlyContinue | Out-Host
-    Write-Host '=== lighthouse stderr ==='
-    Get-Content $lhErr -ErrorAction SilentlyContinue | Out-Host
-    Write-Host '=== peer stdout ==='
-    Get-Content $peerOut -ErrorAction SilentlyContinue | Out-Host
-    Write-Host '=== peer stderr ==='
-    Get-Content $peerErr -ErrorAction SilentlyContinue | Out-Host
-    Write-Host '=== nebula WFP filters ==='
-    # Dump nebula-installed filters so we can verify they got registered with
-    # the conditions we expect.
-    $wfpDump = Join-Path $WorkDir 'wfp.xml'
-    netsh wfp show filters file=$wfpDump 2>&1 | Out-Null
-    if (Test-Path $wfpDump) {
-        Select-String -Path $wfpDump -Pattern 'Nebula' -Context 0,80 -ErrorAction SilentlyContinue | Out-Host
-    }
-    throw
-}
-finally {
-    if (-not $lhProc.HasExited) {
-        Stop-Process -Id $lhProc.Id -Force -ErrorAction SilentlyContinue
-        $lhProc.WaitForExit(5000) | Out-Null
-    }
-    wsl -d $Distro -u root -- bash -c "pkill -f $WslDir/nebula 2>/dev/null; true" | Out-Null
-    # pkill returns 1 when no match and wsl propagates that; the smoke is done
-    # so we don't want it to leak into the script's exit code.
-    $global:LASTEXITCODE = 0
-    if ($peerProc -and -not $peerProc.HasExited) {
-        Stop-Process -Id $peerProc.Id -Force -ErrorAction SilentlyContinue
-    }
-}

.github/workflows/smoke/vagrant-netbsd-amd64/Vagrantfile

@@ -1,7 +1,7 @@
 # -*- mode: ruby -*-
 # vi: set ft=ruby :
 Vagrant.configure("2") do |config|
-  config.vm.box = "DefinedNet/netbsd10"
+  config.vm.box = "generic/netbsd9"
 
   config.vm.synced_folder "../build", "/nebula", type: "rsync"
 end

.github/workflows/test.yml

@@ -45,7 +45,7 @@ jobs:
     - name: Build test mobile
       run: make build-test-mobile
 
-    - uses: actions/upload-artifact@v7
+    - uses: actions/upload-artifact@v6
       with:
         name: e2e packet flow linux-latest
         path: e2e/mermaid/linux-latest
@@ -125,7 +125,7 @@ jobs:
     - name: End 2 end
       run: make e2evv
 
-    - uses: actions/upload-artifact@v7
+    - uses: actions/upload-artifact@v6
       with:
         name: e2e packet flow ${{ matrix.os }}
         path: e2e/mermaid/${{ matrix.os }}

bits.go

@@ -2,42 +2,24 @@ package nebula
 
 import (
 	"context"
-	"fmt"
 	"log/slog"
-	"math"
-	mathbits "math/bits"
 
 	"github.com/rcrowley/go-metrics"
 )
 
-const bitsPerWord = 64
-
-// Bits is a sliding-window anti-replay tracker. The window is stored as a
-// circular bitmap packed into uint64 words (8x denser than a []bool), so a
-// length-N window costs N/8 bytes. length must be a power of two.
 type Bits struct {
 	length             uint64
-	lengthMask         uint64
 	current            uint64
-	bits               []uint64
+	bits               []bool
 	lostCounter        metrics.Counter
 	dupeCounter        metrics.Counter
 	outOfWindowCounter metrics.Counter
 }
 
-func NewBits(length uint64) *Bits {
-	if length == 0 || length&(length-1) != 0 {
-		panic(fmt.Sprintf("Bits length must be a power of two, got %d", length))
-	}
-
-	nWords := length / bitsPerWord
-	if nWords == 0 {
-		nWords = 1
-	}
+func NewBits(bits uint64) *Bits {
 	b := &Bits{
-		length:             length,
-		lengthMask:         length - 1,
-		bits:               make([]uint64, nWords),
+		length:             bits,
+		bits:               make([]bool, bits, bits),
 		current:            0,
 		lostCounter:        metrics.GetOrRegisterCounter("network.packets.lost", nil),
 		dupeCounter:        metrics.GetOrRegisterCounter("network.packets.duplicate", nil),
@@ -45,194 +27,71 @@ func NewBits(length uint64) *Bits {
 	}
 
 	// There is no counter value 0, mark it to avoid counting a lost packet later.
-	b.bits[0] = 1
+	b.bits[0] = true
+	b.current = 0
 	return b
 }
 
-func (b *Bits) get(i uint64) bool {
-	pos := i & b.lengthMask
-	//bit-shifting by 6 because i is a bit index, not a u64 index, and we need to find the u64 without bit in it
-	return b.bits[pos>>6]&(uint64(1)<<(pos&63)) != 0
-}
-
-func (b *Bits) set(i uint64) {
-	pos := i & b.lengthMask
-	b.bits[pos>>6] |= uint64(1) << (pos & 63)
-}
-
-// clearRange clears `count` bits starting at circular position `startPos`
-// (already masked to [0, length)) and returns how many of them were set
-// before the clear. count must be in [1, length].
-func (b *Bits) clearRange(startPos, count uint64) uint64 {
-	wasSet := uint64(0)
-	if count >= b.length {
-		for _, w := range b.bits {
-			wasSet += uint64(mathbits.OnesCount64(w))
-		}
-		clear(b.bits)
-		return wasSet
-	}
-
-	pos := startPos
-	remaining := count
-
-	// handle the potential partial word before pos becomes u64 aligned
-	word := pos >> 6
-	bit := pos & 63
-	take := uint64(64) - bit
-	if take > remaining {
-		take = remaining
-	}
-	if take > b.length-pos {
-		take = b.length - pos
-	}
-	var mask uint64
-	if take == 64 {
-		mask = math.MaxUint64
-	} else {
-		mask = ((uint64(1) << take) - 1) << bit
-	}
-	wasSet += uint64(mathbits.OnesCount64(b.bits[word] & mask))
-	b.bits[word] &^= mask
-	remaining -= take
-	pos = (pos + take) & b.lengthMask
-
-	// Clear whole words, keeping track of the number of set bits
-	for remaining >= 64 {
-		word = pos >> 6
-		wasSet += uint64(mathbits.OnesCount64(b.bits[word]))
-		b.bits[word] = 0
-		remaining -= 64
-		pos = (pos + 64) & b.lengthMask
-	}
-
-	// Clear the remaining partial word
-	if remaining > 0 {
-		word = pos >> 6
-		mask = (uint64(1) << remaining) - 1
-		wasSet += uint64(mathbits.OnesCount64(b.bits[word] & mask))
-		b.bits[word] &^= mask
-	}
-
-	return wasSet
-}
-
-func (b *Bits) strictlyWithinWindow(i uint64) bool {
-	// Handle the case where the window hasn't slid yet. This avoids u64 underflow.
-	inWarmup := b.current < b.length
-	if i < b.length && inWarmup {
-		return true
-	}
-
-	// Next, if the packet is in-window, see if we've seen it before
-	if i > b.current-b.length {
-		return true
-	}
-	return false //not within window!
-}
-
-// Check returns true if i is within (or way out in front of) the window, and not a replay
 func (b *Bits) Check(l *slog.Logger, i uint64) bool {
 	// If i is the next number, return true.
 	if i > b.current {
 		return true
 	}
 
-	if b.strictlyWithinWindow(i) {
-		return !b.get(i)
+	// If i is within the window, check if it's been set already.
+	if i > b.current-b.length || i < b.length && b.current < b.length {
+		return !b.bits[i%b.length]
 	}
 
 	// Not within the window
 	if l.Enabled(context.Background(), slog.LevelDebug) {
-		l.Debug("rejected a packet (top)", "current", b.current, "incoming", i)
+		l.Debug("rejected a packet (top)",
+			"current", b.current,
+			"incoming", i,
+		)
 	}
 	return false
 }
 
-// Update has three branches:
-//   - i == b.current+1: fast path; advance the cursor by one and lose-count
-//     the slot we just stomped (only past warmup; see the i > b.length guard
-//     below).
-//   - i  >  b.current+1: jump path; clear all slots between current and i
-//     (or up to a full window's worth, whichever is smaller) via clearRange,
-//     then mark i. Two arms here: a warmup arm that handles the very first
-//     window before the cursor has slid, and a steady-state arm that treats
-//     every cleared empty slot as a lost packet.
-//   - i  <= b.current: in-window check for duplicates; out-of-window otherwise.
-//
-// NewBits seeds bits[0]=1 so counter 0 looks "received" — Update never
-// clears that marker during warmup (clearRange skips position 0 when
-// startPos=1), and once b.current >= b.length the marker is no longer
-// consulted. The marker prevents a fictitious "lost" hit on the first real
-// counter.
 func (b *Bits) Update(l *slog.Logger, i uint64) bool {
-	// Fast path: i is the next expected counter. Split out so the function
-	// stays small and avoids paying for the slow paths' slog argument-build
-	// stack frame on every call. The bit read/test/write is inlined to
-	// touch the backing word once.
+	// If i is the next number, return true and update current.
 	if i == b.current+1 {
-		pos := i & b.lengthMask
-		word := pos >> 6
-		mask := uint64(1) << (pos & 63)
-		w := b.bits[word]
-		if i > b.length && w&mask == 0 {
+		// Check if the oldest bit was lost since we are shifting the window by 1 and occupying it with this counter
+		// The very first window can only be tracked as lost once we are on the 2nd window or greater
+		if b.bits[i%b.length] == false && i > b.length {
 			b.lostCounter.Inc(1)
 		}
-		b.bits[word] = w | mask
+		b.bits[i%b.length] = true
 		b.current = i
 		return true
 	}
-	return b.updateSlow(l, i)
-}
 
-// updateSlow handles jumps, in-window backfill, dupes, and out-of-window.
-func (b *Bits) updateSlow(l *slog.Logger, i uint64) bool {
 	// If i is a jump, adjust the window, record lost, update current, and return true
 	if i > b.current {
-		end := i
-		if end > b.current+b.length {
-			end = b.current + b.length
-		}
-		count := end - b.current
-		startPos := (b.current + 1) & b.lengthMask
-
-		var lost int64
-		if b.current >= b.length {
-			// Steady state: every cleared slot is past warmup, so any unset
-			// bit we evict is a lost packet from the previous cycle.
-			wasSet := b.clearRange(startPos, count)
-			lost = int64(count) - int64(wasSet)
-		} else {
-			// Warmup (the very first window). Some cleared slots represent
-			// packets <= length where eviction is not "lost" in the usual
-			// sense. This branch is taken at most once per connection so we
-			// don't bother optimizing it.
-			for n := b.current + 1; n <= end; n++ {
-				if !b.get(n) && n > b.length {
-					lost++
-				}
+		lost := int64(0)
+		// Zero out the bits between the current and the new counter value, limited by the window size,
+		// since the window is shifting
+		for n := b.current + 1; n <= min(i, b.current+b.length); n++ {
+			if b.bits[n%b.length] == false && n > b.length {
+				lost++
 			}
-			b.clearRange(startPos, count)
+			b.bits[n%b.length] = false
 		}
 
-		// Anything past the new window can never be backfilled, so it's lost.
-		if i > b.current+b.length {
-			lost += int64(i - b.current - b.length)
-		}
+		// Only record any skipped packets as a result of the window moving further than the window length
+		// Any loss within the new window will be accounted for in future calls
+		lost += max(0, int64(i-b.current-b.length))
 		b.lostCounter.Inc(lost)
 
-		b.set(i)
+		b.bits[i%b.length] = true
 		b.current = i
 		return true
 	}
 
-	// If i is within the current window but below the current counter, check to see if it's a duplicate
-	if b.strictlyWithinWindow(i) {
-		pos := i & b.lengthMask
-		word := pos >> 6
-		mask := uint64(1) << (pos & 63)
-		w := b.bits[word]
-		if b.current == i || w&mask != 0 {
+	// If i is within the current window but below the current counter,
+	// Check to see if it's a duplicate
+	if i > b.current-b.length || i < b.length && b.current < b.length {
+		if b.current == i || b.bits[i%b.length] == true {
 			if l.Enabled(context.Background(), slog.LevelDebug) {
 				l.Debug("Receive window",
 					"accepted", false,
@@ -245,7 +104,7 @@ func (b *Bits) updateSlow(l *slog.Logger, i uint64) bool {
 			return false
 		}
 
-		b.bits[word] = w | mask
+		b.bits[i%b.length] = true
 		return true
 	}
 

bits_test.go

@@ -7,79 +7,61 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-// snapshot returns the bitmap as a []bool of length b.length, for readable
-// test assertions against the now-packed []uint64 storage.
-func (b *Bits) snapshot() []bool {
-	out := make([]bool, b.length)
-	for i := uint64(0); i < b.length; i++ {
-		out[i] = b.get(i)
-	}
-	return out
-}
-
-func TestBitsRequiresPowerOfTwo(t *testing.T) {
-	assert.Panics(t, func() { NewBits(10) })
-	assert.Panics(t, func() { NewBits(0) })
-	assert.NotPanics(t, func() { NewBits(1) })
-	assert.NotPanics(t, func() { NewBits(16) })
-	assert.NotPanics(t, func() { NewBits(1024) })
-	assert.NotPanics(t, func() { NewBits(16384) })
-}
-
 func TestBits(t *testing.T) {
 	l := test.NewLogger()
-	b := NewBits(16)
-	assert.EqualValues(t, 16, b.length)
+	b := NewBits(10)
+
+	// make sure it is the right size
+	assert.Len(t, b.bits, 10)
 
 	// This is initialized to zero - receive one. This should work.
 	assert.True(t, b.Check(l, 1))
 	assert.True(t, b.Update(l, 1))
 	assert.EqualValues(t, 1, b.current)
-	g := []bool{true, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false}
-	assert.Equal(t, g, b.snapshot())
+	g := []bool{true, true, false, false, false, false, false, false, false, false}
+	assert.Equal(t, g, b.bits)
 
 	// Receive two
 	assert.True(t, b.Check(l, 2))
 	assert.True(t, b.Update(l, 2))
 	assert.EqualValues(t, 2, b.current)
-	g = []bool{true, true, true, false, false, false, false, false, false, false, false, false, false, false, false, false}
-	assert.Equal(t, g, b.snapshot())
+	g = []bool{true, true, true, false, false, false, false, false, false, false}
+	assert.Equal(t, g, b.bits)
 
 	// Receive two again - it will fail
 	assert.False(t, b.Check(l, 2))
 	assert.False(t, b.Update(l, 2))
 	assert.EqualValues(t, 2, b.current)
 
-	// Jump ahead to 25, which clears the window and sets slot 25%16 = 9.
-	assert.True(t, b.Check(l, 25))
-	assert.True(t, b.Update(l, 25))
-	assert.EqualValues(t, 25, b.current)
-	g = []bool{false, false, false, false, false, false, false, false, false, true, false, false, false, false, false, false}
-	assert.Equal(t, g, b.snapshot())
+	// Jump ahead to 15, which should clear everything and set the 6th element
+	assert.True(t, b.Check(l, 15))
+	assert.True(t, b.Update(l, 15))
+	assert.EqualValues(t, 15, b.current)
+	g = []bool{false, false, false, false, false, true, false, false, false, false}
+	assert.Equal(t, g, b.bits)
 
-	// Mark 24, which is in window (current 25, length 16, window covers [10,25]).
-	assert.True(t, b.Check(l, 24))
-	assert.True(t, b.Update(l, 24))
-	assert.EqualValues(t, 25, b.current)
-	g = []bool{false, false, false, false, false, false, false, false, true, true, false, false, false, false, false, false}
-	assert.Equal(t, g, b.snapshot())
+	// Mark 14, which is allowed because it is in the window
+	assert.True(t, b.Check(l, 14))
+	assert.True(t, b.Update(l, 14))
+	assert.EqualValues(t, 15, b.current)
+	g = []bool{false, false, false, false, true, true, false, false, false, false}
+	assert.Equal(t, g, b.bits)
 
-	// Mark 5, not allowed because 5 <= current-length (25-16=9).
+	// Mark 5, which is not allowed because it is not in the window
 	assert.False(t, b.Check(l, 5))
 	assert.False(t, b.Update(l, 5))
-	assert.EqualValues(t, 25, b.current)
-	g = []bool{false, false, false, false, false, false, false, false, true, true, false, false, false, false, false, false}
-	assert.Equal(t, g, b.snapshot())
+	assert.EqualValues(t, 15, b.current)
+	g = []bool{false, false, false, false, true, true, false, false, false, false}
+	assert.Equal(t, g, b.bits)
 
-	// Make sure we handle wrapping around once to the same slot. With
-	// length=16, packets 1 and 17 share slot 1.
-	b = NewBits(16)
+	// make sure we handle wrapping around once to the current position
+	b = NewBits(10)
 	assert.True(t, b.Update(l, 1))
-	assert.True(t, b.Update(l, 17))
-	assert.Equal(t, []bool{false, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false}, b.snapshot())
+	assert.True(t, b.Update(l, 11))
+	assert.Equal(t, []bool{false, true, false, false, false, false, false, false, false, false}, b.bits)
 
 	// Walk through a few windows in order
-	b = NewBits(16)
+	b = NewBits(10)
 	for i := uint64(1); i <= 100; i++ {
 		assert.True(t, b.Check(l, i), "Error while checking %v", i)
 		assert.True(t, b.Update(l, i), "Error while updating %v", i)
@@ -90,31 +72,24 @@ func TestBits(t *testing.T) {
 
 func TestBitsLargeJumps(t *testing.T) {
 	l := test.NewLogger()
-
-	// length=16. Update(55) from current=0:
-	//   warmup, per-bit loop sees no n>16 with unset bits (slot 0 was set by
-	//   NewBits and gets re-evaluated when n=16; n=16 is not strictly > 16),
-	//   so the loop contributes 0. The jump exceeds the window so we record
-	//   55 - 0 - 16 = 39 packets fell out the back.
-	b := NewBits(16)
+	b := NewBits(10)
 	b.lostCounter.Clear()
-	assert.True(t, b.Update(l, 55))
-	assert.Equal(t, int64(39), b.lostCounter.Count())
 
-	// Update(100): clears 16 slots starting at slot 56%16=8. Only slot 7 (for
-	// packet 55) was set, so 16 - 1 = 15 evicted slots had unset bits.
-	// Plus 100 - 55 - 16 = 29 packets fell past the window. Total 44.
-	assert.True(t, b.Update(l, 100))
-	assert.Equal(t, int64(39+44), b.lostCounter.Count())
+	b = NewBits(10)
+	b.lostCounter.Clear()
+	assert.True(t, b.Update(l, 55)) // We saw packet 55 and can still track 45,46,47,48,49,50,51,52,53,54
+	assert.Equal(t, int64(45), b.lostCounter.Count())
 
-	// Update(200): same shape: 16 - 1 = 15 evicted unset, plus 200 - 100 - 16 = 84 past window. Total 99.
-	assert.True(t, b.Update(l, 200))
-	assert.Equal(t, int64(39+44+99), b.lostCounter.Count())
+	assert.True(t, b.Update(l, 100)) // We saw packet 55 and 100 and can still track 90,91,92,93,94,95,96,97,98,99
+	assert.Equal(t, int64(89), b.lostCounter.Count())
+
+	assert.True(t, b.Update(l, 200)) // We saw packet 55, 100, and 200 and can still track 190,191,192,193,194,195,196,197,198,199
+	assert.Equal(t, int64(188), b.lostCounter.Count())
 }
 
 func TestBitsDupeCounter(t *testing.T) {
 	l := test.NewLogger()
-	b := NewBits(16)
+	b := NewBits(10)
 	b.lostCounter.Clear()
 	b.dupeCounter.Clear()
 	b.outOfWindowCounter.Clear()
@@ -139,117 +114,120 @@ func TestBitsDupeCounter(t *testing.T) {
 
 func TestBitsOutOfWindowCounter(t *testing.T) {
 	l := test.NewLogger()
-	b := NewBits(16)
+	b := NewBits(10)
 	b.lostCounter.Clear()
 	b.dupeCounter.Clear()
 	b.outOfWindowCounter.Clear()
 
-	// Jump to 20 (warmup branch + 4 past-window packets).
 	assert.True(t, b.Update(l, 20))
 	assert.Equal(t, int64(0), b.outOfWindowCounter.Count())
 
-	// 9 single-step advances, each evicts a slot whose bit was cleared during
-	// the jump above and whose value was never seen, so each contributes 1
-	// to lostCounter.
-	for n := uint64(21); n <= 29; n++ {
-		assert.True(t, b.Update(l, n))
-	}
+	assert.True(t, b.Update(l, 21))
+	assert.True(t, b.Update(l, 22))
+	assert.True(t, b.Update(l, 23))
+	assert.True(t, b.Update(l, 24))
+	assert.True(t, b.Update(l, 25))
+	assert.True(t, b.Update(l, 26))
+	assert.True(t, b.Update(l, 27))
+	assert.True(t, b.Update(l, 28))
+	assert.True(t, b.Update(l, 29))
 	assert.Equal(t, int64(0), b.outOfWindowCounter.Count())
 
-	// 0 is below current-length (29-16=13) so it falls outside the window.
 	assert.False(t, b.Update(l, 0))
 	assert.Equal(t, int64(1), b.outOfWindowCounter.Count())
 
-	// 4 from the Update(20) jump + 9 from 21..29.
-	assert.Equal(t, int64(13), b.lostCounter.Count())
+	assert.Equal(t, int64(19), b.lostCounter.Count()) // packet 0 wasn't lost
 	assert.Equal(t, int64(0), b.dupeCounter.Count())
 	assert.Equal(t, int64(1), b.outOfWindowCounter.Count())
 }
 
 func TestBitsLostCounter(t *testing.T) {
 	l := test.NewLogger()
-	b := NewBits(16)
+	b := NewBits(10)
 	b.lostCounter.Clear()
 	b.dupeCounter.Clear()
 	b.outOfWindowCounter.Clear()
 
-	// Walk 20..29 like the original, just with a bigger window. Same
-	// reasoning as TestBitsOutOfWindowCounter: 4 past-window from Update(20),
-	// then 9 more from the unit advances.
-	for n := uint64(20); n <= 29; n++ {
-		assert.True(t, b.Update(l, n))
-	}
-	assert.Equal(t, int64(13), b.lostCounter.Count())
+	assert.True(t, b.Update(l, 20))
+	assert.True(t, b.Update(l, 21))
+	assert.True(t, b.Update(l, 22))
+	assert.True(t, b.Update(l, 23))
+	assert.True(t, b.Update(l, 24))
+	assert.True(t, b.Update(l, 25))
+	assert.True(t, b.Update(l, 26))
+	assert.True(t, b.Update(l, 27))
+	assert.True(t, b.Update(l, 28))
+	assert.True(t, b.Update(l, 29))
+	assert.Equal(t, int64(19), b.lostCounter.Count()) // packet 0 wasn't lost
 	assert.Equal(t, int64(0), b.dupeCounter.Count())
 	assert.Equal(t, int64(0), b.outOfWindowCounter.Count())
 
-	b = NewBits(16)
+	b = NewBits(10)
 	b.lostCounter.Clear()
 	b.dupeCounter.Clear()
 	b.outOfWindowCounter.Clear()
 
-	// Update(15) clears the warmup window (no lost), sets slot 15.
-	assert.True(t, b.Update(l, 15))
+	assert.True(t, b.Update(l, 9))
 	assert.Equal(t, int64(0), b.lostCounter.Count())
-
-	// Update(16): slot 0 was already set (NewBits seeded it), and 16 is not
-	// strictly > length, so nothing is recorded as lost.
-	assert.True(t, b.Update(l, 16))
+	// 10 will set 0 index, 0 was already set, no lost packets
+	assert.True(t, b.Update(l, 10))
 	assert.Equal(t, int64(0), b.lostCounter.Count())
-
-	// Update(17): we jumped straight from 0 to 15, so slot 1 was cleared
-	// (and never re-set). 17 > 16 is past warmup, so packet 1 is recorded lost.
-	assert.True(t, b.Update(l, 17))
+	// 11 will set 1 index, 1 was missed, we should see 1 packet lost
+	assert.True(t, b.Update(l, 11))
 	assert.Equal(t, int64(1), b.lostCounter.Count())
+	// Now let's fill in the window, should end up with 8 lost packets
+	assert.True(t, b.Update(l, 12))
+	assert.True(t, b.Update(l, 13))
+	assert.True(t, b.Update(l, 14))
+	assert.True(t, b.Update(l, 15))
+	assert.True(t, b.Update(l, 16))
+	assert.True(t, b.Update(l, 17))
+	assert.True(t, b.Update(l, 18))
+	assert.True(t, b.Update(l, 19))
+	assert.Equal(t, int64(8), b.lostCounter.Count())
 
-	// Fill in 18..30 in single steps. Each i evicts slot i%16. Slots 2..14
-	// were all cleared during Update(15), and we never re-set any of them,
-	// so each i in 18..30 is a fresh lost packet — 13 more.
-	for n := uint64(18); n <= 30; n++ {
-		assert.True(t, b.Update(l, n))
-	}
-	assert.Equal(t, int64(14), b.lostCounter.Count())
+	// Jump ahead by a window size
+	assert.True(t, b.Update(l, 29))
+	assert.Equal(t, int64(8), b.lostCounter.Count())
+	// Now lets walk ahead normally through the window, the missed packets should fill in
+	assert.True(t, b.Update(l, 30))
+	assert.True(t, b.Update(l, 31))
+	assert.True(t, b.Update(l, 32))
+	assert.True(t, b.Update(l, 33))
+	assert.True(t, b.Update(l, 34))
+	assert.True(t, b.Update(l, 35))
+	assert.True(t, b.Update(l, 36))
+	assert.True(t, b.Update(l, 37))
+	assert.True(t, b.Update(l, 38))
+	// 39 packets tracked, 22 seen, 17 lost
+	assert.Equal(t, int64(17), b.lostCounter.Count())
 
-	// Jump ahead by exactly one window size.
-	assert.True(t, b.Update(l, 46))
-	// end = min(46, 30+16) = 46, count = 16, all slots cleared. Before the
-	// jump every slot 0..15 had been set (Update(15), (16), (17), 18..30),
-	// so wasSet=16 and 46 == current+length means no past-window slack:
-	// lost contribution = 0.
-	assert.Equal(t, int64(14), b.lostCounter.Count())
-
-	// Walk 47..55. The Update(46) jump cleared every slot, so only slot 14
-	// (for packet 46) is set when we start. Each subsequent unit step lands
-	// on a slot that was cleared and is past warmup, so it counts as lost.
-	// 9 more = 23.
-	for n := uint64(47); n <= 55; n++ {
-		assert.True(t, b.Update(l, n))
-	}
-	assert.Equal(t, int64(23), b.lostCounter.Count())
-
-	// Jump ahead by two windows: clears the window plus past-window loss.
-	assert.True(t, b.Update(l, 87))
-	// current=55, length=16. end = min(87, 71) = 71. count=16, all slots
-	// cleared. Slots set before the clear are slots 14,15,0..7 (10 total).
-	// Lost from clear = 16 - 10 = 6. Past window: 87 - 55 - 16 = 16. +22.
-	assert.Equal(t, int64(45), b.lostCounter.Count())
+	// Jump ahead by 2 windows, should have recording 1 full window missing
+	assert.True(t, b.Update(l, 58))
+	assert.Equal(t, int64(27), b.lostCounter.Count())
+	// Now lets walk ahead normally through the window, the missed packets should fill in from this window
+	assert.True(t, b.Update(l, 59))
+	assert.True(t, b.Update(l, 60))
+	assert.True(t, b.Update(l, 61))
+	assert.True(t, b.Update(l, 62))
+	assert.True(t, b.Update(l, 63))
+	assert.True(t, b.Update(l, 64))
+	assert.True(t, b.Update(l, 65))
+	assert.True(t, b.Update(l, 66))
+	assert.True(t, b.Update(l, 67))
+	// 68 packets tracked, 32 seen, 36 missed
+	assert.Equal(t, int64(36), b.lostCounter.Count())
 	assert.Equal(t, int64(0), b.dupeCounter.Count())
 	assert.Equal(t, int64(0), b.outOfWindowCounter.Count())
 }
 
 func TestBitsLostCounterIssue1(t *testing.T) {
 	l := test.NewLogger()
-	b := NewBits(16)
+	b := NewBits(10)
 	b.lostCounter.Clear()
 	b.dupeCounter.Clear()
 	b.outOfWindowCounter.Clear()
 
-	// Receive 4, backfill 1, then 9, 2, 3, 5, 6, 7 (skip 8), 10, 11, 14.
-	// Then jump to 25 — slot 25%16=9 is being evicted, but it had been set
-	// (we received packet 9), so no spurious lost increment. The original
-	// regression was about double-counting a missing packet when its slot
-	// got cleared on a jump. With the jump path now using clearRange's
-	// word-level wasSet count, the same semantics hold.
 	assert.True(t, b.Update(l, 4))
 	assert.Equal(t, int64(0), b.lostCounter.Count())
 	assert.True(t, b.Update(l, 1))
@@ -266,7 +244,7 @@ func TestBitsLostCounterIssue1(t *testing.T) {
 	assert.Equal(t, int64(0), b.lostCounter.Count())
 	assert.True(t, b.Update(l, 7))
 	assert.Equal(t, int64(0), b.lostCounter.Count())
-	// Skip packet 8.
+	// assert.True(t, b.Update(l, 8))
 	assert.True(t, b.Update(l, 10))
 	assert.Equal(t, int64(0), b.lostCounter.Count())
 	assert.True(t, b.Update(l, 11))
@@ -274,23 +252,9 @@ func TestBitsLostCounterIssue1(t *testing.T) {
 
 	assert.True(t, b.Update(l, 14))
 	assert.Equal(t, int64(0), b.lostCounter.Count())
-
-	// Jump to 25. With length=16, slot 25%16=9 corresponds to packet 9
-	// (which we DID receive), so its bit is set and no lost++ from that
-	// eviction. The trace below shows the only loss is packet 8.
-	assert.True(t, b.Update(l, 25))
-	// current was 14, i=25. end=min(25,30)=25. count=11. startPos=15.
-	// steady? current=14<16, so warmup branch: per-bit n=15..25, count those
-	// with !get(n) AND n>16. n=17..25 are >16. Among slots 17%16=1..25%16=9
-	// did we set slots 1..9 (packets 1..9)? Yes for all but slot 8 (packet 8
-	// was skipped). n=24 maps to slot 8 which is FALSE → lost++. All other
-	// n in 17..25 map to slots that are set. n=16 is not strictly > 16. So
-	// lost = 1.
+	// Issue seems to be here, we reset missing packet 8 to false here and don't increment the lost counter
+	assert.True(t, b.Update(l, 19))
 	assert.Equal(t, int64(1), b.lostCounter.Count())
-
-	// Fill in 12, 13, 15, 16. Each is below current=25 (in-window). 16 must
-	// recheck slot 0 — it was set by NewBits and then cleared by the
-	// Update(25) jump, so 16 backfills cleanly.
 	assert.True(t, b.Update(l, 12))
 	assert.Equal(t, int64(1), b.lostCounter.Count())
 	assert.True(t, b.Update(l, 13))
@@ -299,140 +263,29 @@ func TestBitsLostCounterIssue1(t *testing.T) {
 	assert.Equal(t, int64(1), b.lostCounter.Count())
 	assert.True(t, b.Update(l, 16))
 	assert.Equal(t, int64(1), b.lostCounter.Count())
+	assert.True(t, b.Update(l, 17))
+	assert.Equal(t, int64(1), b.lostCounter.Count())
+	assert.True(t, b.Update(l, 18))
+	assert.Equal(t, int64(1), b.lostCounter.Count())
+	assert.True(t, b.Update(l, 20))
+	assert.Equal(t, int64(1), b.lostCounter.Count())
+	assert.True(t, b.Update(l, 21))
 
-	// We missed packet 8 above and that loss is still recorded once, never
-	// double-counted, never zeroed.
+	// We missed packet 8 above
 	assert.Equal(t, int64(1), b.lostCounter.Count())
 	assert.Equal(t, int64(0), b.dupeCounter.Count())
 	assert.Equal(t, int64(0), b.outOfWindowCounter.Count())
 }
 
-// TestBitsWarmupOvershoot exercises the jump path's warmup arm with an
-// overshoot past one full window. NewBits leaves current=0 with only slot 0
-// "set" by the marker. Jumping straight to length+k must (a) clear every
-// slot the jump straddles, (b) count only past-window slack (not the
-// in-window slots, which never had a "lost" tenant during warmup), and
-// (c) leave the cursor at the new counter so subsequent unit advances
-// count from steady state. The marker bit at slot 0 is irrelevant once
-// current >= length.
-func TestBitsWarmupOvershoot(t *testing.T) {
-	l := test.NewLogger()
-	b := NewBits(16)
-	b.lostCounter.Clear()
-
-	// Jump from current=0 to i=20 (length=16, overshoot=4).
-	// Warmup arm: counts slots in [1..16] where bit unset and n>length.
-	// Only n=16 was unset and >length: but slot 16%16=0 is the marker,
-	// so b.get(16) reads bits[0]=1 and skips. Result: 0 lost from the loop.
-	// Past-window: i - current - length = 20 - 0 - 16 = 4 lost.
-	assert.True(t, b.Update(l, 20))
-	assert.Equal(t, int64(4), b.lostCounter.Count())
-	assert.Equal(t, uint64(20), b.current)
-
-	// Steady state now (current=20 >= length=16). Unit advance to 21
-	// stomps slot 21%16=5, which was cleared by the jump and not reset,
-	// so this is +1 lost.
-	assert.True(t, b.Update(l, 21))
-	assert.Equal(t, int64(5), b.lostCounter.Count())
-}
-
-// TestBitsCheckAcrossWarmupBoundary pins the underflow trick in Check's
-// in-window clause. While in warmup, b.current-b.length underflows uint64
-// to a huge value so the first OR-clause is always false; the second
-// clause (i < length && current < length) carries the in-window check.
-// Once current >= length the regimes flip cleanly.
-func TestBitsCheckAcrossWarmupBoundary(t *testing.T) {
-	l := test.NewLogger()
-	b := NewBits(16)
-
-	// Warmup: current=0. Check(0) must read the marker (set) and return false.
-	assert.False(t, b.Check(l, 0), "marker slot should look already-received")
-	// Warmup: any 0 < i < length is in-window and unset → accepted.
-	for i := uint64(1); i < 16; i++ {
-		assert.True(t, b.Check(l, i), "warmup in-window i=%d should be accepted", i)
-	}
-	// Warmup: i >= length but > current is "next number" so accepted.
-	assert.True(t, b.Check(l, 16))
-	assert.True(t, b.Check(l, 1_000_000))
-
-	// Cross into steady state.
-	assert.True(t, b.Update(l, 100))
-	// Now current=100, length=16. In-window range is [85..100].
-	// 84 is just outside: the underflow clause activates; 84 > 100-16=84 is false.
-	// And the warmup clause is false (current >= length). So out of window.
-	assert.False(t, b.Check(l, 84))
-	// 85 sits at the boundary. 85 > 84 is true → in window, unset → accept.
-	assert.True(t, b.Check(l, 85))
-	// 100 is current itself; not strictly greater, in-window, but already set.
-	assert.False(t, b.Check(l, 100))
-	// Way out: clearly out of window.
-	assert.False(t, b.Check(l, 50))
-}
-
-// TestBitsMarkerInvariant verifies the seeded bits[0]=1 marker behaves
-// correctly across warmup and beyond. Update should never clear the marker
-// during warmup (clearRange skips position 0 when startPos=1), and once
-// current >= length the marker is no longer consulted by Check/Update on
-// the live path — but it must still report counter 0 as a duplicate while
-// we are in warmup.
-func TestBitsMarkerInvariant(t *testing.T) {
-	l := test.NewLogger()
-	b := NewBits(8)
-
-	// Counter 0 is the seeded marker; Check sees it as already received.
-	assert.False(t, b.Check(l, 0))
-	// Update(0) at current=0 hits the duplicate branch.
-	b.dupeCounter.Clear()
-	assert.False(t, b.Update(l, 0))
-	assert.Equal(t, int64(1), b.dupeCounter.Count())
-
-	// Walk forward through warmup; the marker must remain set.
-	for n := uint64(1); n <= 7; n++ {
-		assert.True(t, b.Update(l, n))
-	}
-	// Position 0 (the marker) should still read as set because we never
-	// cleared it; Update(0) still looks like a duplicate.
-	assert.False(t, b.Check(l, 0))
-
-	// Cross into steady state with a unit advance to 8: pos=0, evicts the
-	// marker bit. The lost-counter guard (i > b.length) is false (8 == 8),
-	// so this advance does NOT charge a lost packet — exactly what the
-	// marker is there to prevent.
-	b.lostCounter.Clear()
-	assert.True(t, b.Update(l, 8))
-	assert.Equal(t, int64(0), b.lostCounter.Count())
-	// The slot at pos 0 is now occupied by counter 8.
-	assert.False(t, b.Check(l, 8))
-}
-
-// BenchmarkBitsUpdateInOrder is the steady-state hot path: each call is
-// i == current+1.
-func BenchmarkBitsUpdateInOrder(b *testing.B) {
-	l := test.NewLogger()
-	z := NewBits(16384)
+func BenchmarkBits(b *testing.B) {
+	z := NewBits(10)
 	for n := 0; n < b.N; n++ {
-		z.Update(l, uint64(n)+1)
-	}
-}
+		for i := range z.bits {
+			z.bits[i] = true
+		}
+		for i := range z.bits {
+			z.bits[i] = false
+		}
 
-// BenchmarkBitsUpdateReorder simulates light reorder within the window:
-// every other packet arrives one slot behind its predecessor (forces the
-// in-window backfill branch).
-func BenchmarkBitsUpdateReorder(b *testing.B) {
-	l := test.NewLogger()
-	z := NewBits(16384)
-	for n := 0; n < b.N; n++ {
-		base := uint64(n) * 2
-		z.Update(l, base+2)
-		z.Update(l, base+1)
-	}
-}
-
-// BenchmarkBitsUpdateLargeJumps stresses the clearRange word-level path.
-func BenchmarkBitsUpdateLargeJumps(b *testing.B) {
-	l := test.NewLogger()
-	z := NewBits(16384)
-	for n := 0; n < b.N; n++ {
-		z.Update(l, uint64(n+1)*1000)
 	}
 }

cert/ca_pool.go

@@ -217,10 +217,6 @@ func (ncp *CAPool) verify(c Certificate, now time.Time, certFp string, signerFp
 		return nil, err
 	}
 
-	if signer.Certificate.Curve() != c.Curve() {
-		return nil, ErrCurveMismatch
-	}
-
 	if signer.Certificate.Expired(now) {
 		return nil, ErrRootExpired
 	}

cert/ca_pool_test.go

@@ -654,31 +654,3 @@ func TestCertificateV2_Verify_Subnets(t *testing.T) {
 	_, err = caPool.VerifyCertificate(time.Now(), c)
 	require.NoError(t, err)
 }
-
-func TestCertificateV2_CurveMismatch(t *testing.T) {
-	caIp1 := mustParsePrefixUnmapped("10.0.0.0/16")
-	caIp2 := mustParsePrefixUnmapped("192.168.0.0/24")
-	ca, _, caKey, _ := NewTestCaCert(Version2, Curve_P256, time.Now(), time.Now().Add(10*time.Minute), []netip.Prefix{caIp1, caIp2}, nil, []string{"test"})
-
-	caPem, err := ca.MarshalPEM()
-	require.NoError(t, err)
-
-	caPool := NewCAPool()
-	b, err := caPool.AddCAFromPEM(caPem)
-	require.NoError(t, err)
-	assert.Empty(t, b)
-
-	// ip is outside the network
-	cIp1 := mustParsePrefixUnmapped("10.0.0.1/24")
-	c, _, _, _ := NewTestCert(Version2, Curve_P256, ca, caKey, "test", time.Now(), time.Now().Add(5*time.Minute), []netip.Prefix{cIp1}, nil, []string{"test"})
-
-	fp, _ := c.Fingerprint()
-	_, err = caPool.verify(c, time.Now(), fp, c.Issuer())
-	require.NoError(t, err)
-	//
-	c2 := c.(*certificateV2)
-	c2.curve = Curve_CURVE25519
-	fp, _ = c.Fingerprint()
-	_, err = caPool.verify(c, time.Now(), fp, c.Issuer())
-	require.Error(t, err)
-}

cert/cert_v1.go

@@ -112,9 +112,6 @@ func (c *certificateV1) CheckSignature(key []byte) bool {
 	}
 	switch c.details.curve {
 	case Curve_CURVE25519:
-		if len(key) != ed25519.PublicKeySize {
-			return false //avoids a panic internal to ed25519
-		}
 		return ed25519.Verify(key, b, c.signature)
 	case Curve_P256:
 		pubKey, err := ecdsa.ParseUncompressedPublicKey(elliptic.P256(), key)

cert/cert_v2.go

@@ -151,9 +151,6 @@ func (c *certificateV2) CheckSignature(key []byte) bool {
 
 	switch c.curve {
 	case Curve_CURVE25519:
-		if len(key) != ed25519.PublicKeySize {
-			return false //avoids a panic internal to ed25519
-		}
 		return ed25519.Verify(key, b, c.signature)
 	case Curve_P256:
 		pubKey, err := ecdsa.ParseUncompressedPublicKey(elliptic.P256(), key)

cert/errors.go

@@ -22,7 +22,6 @@ var (
 	ErrCaNotFound                 = errors.New("could not find ca for the certificate")
 	ErrUnknownVersion             = errors.New("certificate version unrecognized")
 	ErrCertPubkeyPresent          = errors.New("certificate has unexpected pubkey present")
-	ErrCurveMismatch              = errors.New("certificate curve does not match CA")
 
 	ErrInvalidPEMBlock                   = errors.New("input did not contain a valid PEM encoded block")
 	ErrInvalidPEMCertificateBanner       = errors.New("bytes did not contain a proper certificate banner")

connection_manager.go

@@ -11,6 +11,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/rcrowley/go-metrics"
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/header"
@@ -44,16 +45,19 @@ type connectionManager struct {
 	inactivityTimeout       atomic.Int64
 	dropInactive            atomic.Bool
 
+	metricsTxPunchy metrics.Counter
+
 	l *slog.Logger
 }
 
 func newConnectionManagerFromConfig(l *slog.Logger, c *config.C, hm *HostMap, p *Punchy) *connectionManager {
 	cm := &connectionManager{
-		hostMap:       hm,
-		l:             l,
-		punchy:        p,
-		relayUsed:     make(map[uint32]struct{}),
-		relayUsedLock: &sync.RWMutex{},
+		hostMap:         hm,
+		l:               l,
+		punchy:          p,
+		relayUsed:       make(map[uint32]struct{}),
+		relayUsedLock:   &sync.RWMutex{},
+		metricsTxPunchy: metrics.GetOrRegisterCounter("messages.tx.punchy", nil),
 	}
 
 	cm.reload(c, true)
@@ -149,8 +153,8 @@ func (cm *connectionManager) Start(ctx context.Context) {
 	defer clockSource.Stop()
 
 	p := []byte("")
-	nb := make([]byte, 12, 12)
-	out := make([]byte, mtu)
+	// Long-lived buf for the traffic-check goroutine; never released.
+	buf := cm.intf.bufAlloc.Acquire()
 
 	for {
 		select {
@@ -165,13 +169,13 @@ func (cm *connectionManager) Start(ctx context.Context) {
 					break
 				}
 
-				cm.doTrafficCheck(localIndex, p, nb, out, now)
+				cm.doTrafficCheck(localIndex, p, buf, now)
 			}
 		}
 	}
 }
 
-func (cm *connectionManager) doTrafficCheck(localIndex uint32, p, nb, out []byte, now time.Time) {
+func (cm *connectionManager) doTrafficCheck(localIndex uint32, p []byte, buf *WireBuffer, now time.Time) {
 	decision, hostinfo, primary := cm.makeTrafficDecision(localIndex, now)
 
 	switch decision {
@@ -195,7 +199,7 @@ func (cm *connectionManager) doTrafficCheck(localIndex uint32, p, nb, out []byte
 		cm.tryRehandshake(hostinfo)
 
 	case sendTestPacket:
-		cm.intf.SendMessageToHostInfo(header.Test, header.TestRequest, hostinfo, p, nb, out)
+		cm.intf.SendMessageToHostInfo(header.Test, header.TestRequest, hostinfo, p, buf)
 	}
 
 	cm.resetRelayTrafficCheck(hostinfo)
@@ -304,7 +308,9 @@ func (cm *connectionManager) migrateRelayUsed(oldhostinfo, newhostinfo *HostInfo
 		if err != nil {
 			cm.l.Error("failed to marshal Control message to migrate relay", "error", err)
 		} else {
-			cm.intf.SendMessageToHostInfo(header.Control, 0, newhostinfo, msg, make([]byte, 12), make([]byte, mtu))
+			migBuf := cm.intf.bufAlloc.Acquire()
+			cm.intf.SendMessageToHostInfo(header.Control, 0, newhostinfo, msg, migBuf)
+			cm.intf.bufAlloc.Release(migBuf)
 			cm.l.Info("send CreateRelayRequest",
 				"relayFrom", req.RelayFromAddr,
 				"relayTo", req.RelayToAddr,
@@ -365,7 +371,7 @@ func (cm *connectionManager) makeTrafficDecision(localIndex uint32, now time.Tim
 
 		if !outTraffic {
 			// Send a punch packet to keep the NAT state alive
-			cm.punchy.SendPunch(hostinfo)
+			cm.sendPunch(hostinfo)
 		}
 
 		return decision, hostinfo, primary
@@ -396,16 +402,17 @@ func (cm *connectionManager) makeTrafficDecision(localIndex uint32, now time.Tim
 
 			// If we aren't sending or receiving traffic then its an unused tunnel and we don't to test the tunnel.
 			// Just maintain NAT state if configured to do so.
-			cm.punchy.SendPunch(hostinfo)
+			cm.sendPunch(hostinfo)
 			cm.trafficTimer.Add(hostinfo.localIndexId, cm.checkInterval)
 			return doNothing, nil, nil
 		}
 
-		// We aren't receiving traffic but we are sending it. The outbound
-		// traffic itself refreshes the primary remote's NAT state; this
-		// fans out to non-primary remotes, but only if target_all_remotes
-		// is configured.
-		cm.punchy.SendPunchToAll(hostinfo)
+		if cm.punchy.GetTargetEverything() {
+			// This is similar to the old punchy behavior with a slight optimization.
+			// We aren't receiving traffic but we are sending it, punch on all known
+			// ips in case we need to re-prime NAT state
+			cm.sendPunch(hostinfo)
+		}
 
 		if cm.l.Enabled(context.Background(), slog.LevelDebug) {
 			hostinfo.logger(cm.l).Debug("Tunnel status",
@@ -507,6 +514,31 @@ func (cm *connectionManager) isInvalidCertificate(now time.Time, hostinfo *HostI
 	}
 }
 
+func (cm *connectionManager) sendPunch(hostinfo *HostInfo) {
+	if !cm.punchy.GetPunch() {
+		// Punching is disabled
+		return
+	}
+
+	if cm.intf.lightHouse.IsAnyLighthouseAddr(hostinfo.vpnAddrs) {
+		// Do not punch to lighthouses, we assume our lighthouse update interval is good enough.
+		// In the event the update interval is not sufficient to maintain NAT state then a publicly available lighthouse
+		// would lose the ability to notify us and punchy.respond would become unreliable.
+		return
+	}
+
+	if cm.punchy.GetTargetEverything() {
+		hostinfo.remotes.ForEach(cm.hostMap.GetPreferredRanges(), func(addr netip.AddrPort, preferred bool) {
+			cm.metricsTxPunchy.Inc(1)
+			cm.intf.outside.WriteTo([]byte{1}, addr)
+		})
+
+	} else if hostinfo.remote.IsValid() {
+		cm.metricsTxPunchy.Inc(1)
+		cm.intf.outside.WriteTo([]byte{1}, hostinfo.remote)
+	}
+}
+
 func (cm *connectionManager) tryRehandshake(hostinfo *HostInfo) {
 	cs := cm.intf.pki.getCertState()
 	curCrt := hostinfo.ConnectionState.myCert

connection_manager_test.go

@@ -64,12 +64,12 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 
 	// Create manager
 	conf := config.NewC(test.NewLogger())
-	punchy := NewPunchyFromConfig(test.NewLogger(), conf, nil)
+	punchy := NewPunchyFromConfig(test.NewLogger(), conf)
 	nc := newConnectionManagerFromConfig(test.NewLogger(), conf, hostMap, punchy)
 	nc.intf = ifce
+
 	p := []byte("")
-	nb := make([]byte, 12, 12)
-	out := make([]byte, mtu)
+	buf := NewWireBuffer(mtu, 0)
 
 	// Add an ip we have established a connection w/ to hostmap
 	hostinfo := &HostInfo{
@@ -92,7 +92,7 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 	assert.True(t, hostinfo.in.Load())
 
 	// Do a traffic check tick, should not be pending deletion but should not have any in/out packets recorded
-	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
+	nc.doTrafficCheck(hostinfo.localIndexId, p, buf, time.Now())
 	assert.False(t, hostinfo.pendingDeletion.Load())
 	assert.False(t, hostinfo.out.Load())
 	assert.False(t, hostinfo.in.Load())
@@ -100,7 +100,7 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 	// Do another traffic check tick, this host should be pending deletion now
 	nc.Out(hostinfo)
 	assert.True(t, hostinfo.out.Load())
-	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
+	nc.doTrafficCheck(hostinfo.localIndexId, p, buf, time.Now())
 	assert.True(t, hostinfo.pendingDeletion.Load())
 	assert.False(t, hostinfo.out.Load())
 	assert.False(t, hostinfo.in.Load())
@@ -108,7 +108,7 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])
 
 	// Do a final traffic check tick, the host should now be removed
-	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
+	nc.doTrafficCheck(hostinfo.localIndexId, p, buf, time.Now())
 	assert.NotContains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs)
 	assert.NotContains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 }
@@ -146,12 +146,12 @@ func Test_NewConnectionManagerTest2(t *testing.T) {
 
 	// Create manager
 	conf := config.NewC(test.NewLogger())
-	punchy := NewPunchyFromConfig(test.NewLogger(), conf, nil)
+	punchy := NewPunchyFromConfig(test.NewLogger(), conf)
 	nc := newConnectionManagerFromConfig(test.NewLogger(), conf, hostMap, punchy)
 	nc.intf = ifce
+
 	p := []byte("")
-	nb := make([]byte, 12, 12)
-	out := make([]byte, mtu)
+	buf := NewWireBuffer(mtu, 0)
 
 	// Add an ip we have established a connection w/ to hostmap
 	hostinfo := &HostInfo{
@@ -174,14 +174,14 @@ func Test_NewConnectionManagerTest2(t *testing.T) {
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 
 	// Do a traffic check tick, should not be pending deletion but should not have any in/out packets recorded
-	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
+	nc.doTrafficCheck(hostinfo.localIndexId, p, buf, time.Now())
 	assert.False(t, hostinfo.pendingDeletion.Load())
 	assert.False(t, hostinfo.out.Load())
 	assert.False(t, hostinfo.in.Load())
 
 	// Do another traffic check tick, this host should be pending deletion now
 	nc.Out(hostinfo)
-	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
+	nc.doTrafficCheck(hostinfo.localIndexId, p, buf, time.Now())
 	assert.True(t, hostinfo.pendingDeletion.Load())
 	assert.False(t, hostinfo.out.Load())
 	assert.False(t, hostinfo.in.Load())
@@ -190,7 +190,7 @@ func Test_NewConnectionManagerTest2(t *testing.T) {
 
 	// We saw traffic, should no longer be pending deletion
 	nc.In(hostinfo)
-	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
+	nc.doTrafficCheck(hostinfo.localIndexId, p, buf, time.Now())
 	assert.False(t, hostinfo.pendingDeletion.Load())
 	assert.False(t, hostinfo.out.Load())
 	assert.False(t, hostinfo.in.Load())
@@ -233,7 +233,7 @@ func Test_NewConnectionManager_DisconnectInactive(t *testing.T) {
 	conf.Settings["tunnels"] = map[string]any{
 		"drop_inactive": true,
 	}
-	punchy := NewPunchyFromConfig(test.NewLogger(), conf, nil)
+	punchy := NewPunchyFromConfig(test.NewLogger(), conf)
 	nc := newConnectionManagerFromConfig(test.NewLogger(), conf, hostMap, punchy)
 	assert.True(t, nc.dropInactive.Load())
 	nc.intf = ifce
@@ -358,7 +358,7 @@ func Test_NewConnectionManagerTest_DisconnectInvalid(t *testing.T) {
 
 	// Create manager
 	conf := config.NewC(test.NewLogger())
-	punchy := NewPunchyFromConfig(test.NewLogger(), conf, nil)
+	punchy := NewPunchyFromConfig(test.NewLogger(), conf)
 	nc := newConnectionManagerFromConfig(test.NewLogger(), conf, hostMap, punchy)
 	nc.intf = ifce
 	ifce.connectionManager = nc

connection_state.go

@@ -7,14 +7,13 @@ import (
 
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/handshake"
-	"github.com/slackhq/nebula/noiseutil"
 )
 
-const ReplayWindow = 8192
+const ReplayWindow = 1024
 
 type ConnectionState struct {
-	eKey           noiseutil.CipherState
-	dKey           noiseutil.CipherState
+	eKey           *NebulaCipherState
+	dKey           *NebulaCipherState
 	myCert         cert.Certificate
 	peerCert       *cert.CachedCertificate
 	initiator      bool
@@ -32,8 +31,8 @@ func newConnectionStateFromResult(r *handshake.Result) *ConnectionState {
 		myCert:    r.MyCert,
 		initiator: r.Initiator,
 		peerCert:  r.RemoteCert,
-		eKey:      noiseutil.NewCipherState(r.EKey, r.Cipher),
-		dKey:      noiseutil.NewCipherState(r.DKey, r.Cipher),
+		eKey:      NewNebulaCipherState(r.EKey),
+		dKey:      NewNebulaCipherState(r.DKey),
 		window:    NewBits(ReplayWindow),
 	}
 	ci.messageCounter.Add(r.MessageIndex)

control.go

@@ -278,15 +278,9 @@ func (c *Control) CloseTunnel(vpnIp netip.Addr, localOnly bool) bool {
 	}
 
 	if !localOnly {
-		c.f.send(
-			header.CloseTunnel,
-			0,
-			hostInfo.ConnectionState,
-			hostInfo,
-			[]byte{},
-			make([]byte, 12, 12),
-			make([]byte, mtu),
-		)
+		buf := c.f.bufAlloc.Acquire()
+		c.f.send(header.CloseTunnel, 0, hostInfo.ConnectionState, hostInfo, []byte{}, buf)
+		c.f.bufAlloc.Release(buf)
 	}
 
 	c.f.closeTunnel(hostInfo)
@@ -296,11 +290,14 @@ func (c *Control) CloseTunnel(vpnIp netip.Addr, localOnly bool) bool {
 // CloseAllTunnels is just like CloseTunnel except it goes through and shuts them all down, optionally you can avoid shutting down lighthouse tunnels
 // the int returned is a count of tunnels closed
 func (c *Control) CloseAllTunnels(excludeLighthouses bool) (closed int) {
+	// One WireBuffer for the whole shutdown loop.
+	buf := c.f.bufAlloc.Acquire()
+	defer c.f.bufAlloc.Release(buf)
 	shutdown := func(h *HostInfo) {
 		if excludeLighthouses && c.f.lightHouse.IsAnyLighthouseAddr(h.vpnAddrs) {
 			return
 		}
-		c.f.send(header.CloseTunnel, 0, h.ConnectionState, h, []byte{}, make([]byte, 12, 12), make([]byte, mtu))
+		c.f.send(header.CloseTunnel, 0, h.ConnectionState, h, []byte{}, buf)
 		c.f.closeTunnel(h)
 
 		c.l.Debug("Sending close tunnel message",

e2e/bench_test.go

@@ -0,0 +1,68 @@
+//go:build e2e_testing
+// +build e2e_testing
+
+package e2e
+
+import (
+	"testing"
+	"time"
+
+	"github.com/slackhq/nebula/cert"
+	"github.com/slackhq/nebula/cert_test"
+	"github.com/slackhq/nebula/e2e/router"
+)
+
+// BenchmarkHandshake measures end-to-end tunnel establishment time. The two
+// nodes and the router are constructed once before the loop so the timed window
+// is just the handshake itself: trigger packet -> handshake1 -> handshake2 ->
+// cached packet replay -> arrival on the remote TUN. Between iterations we
+// tear down both sides locally (no CloseTunnel notification on the wire) and
+// re-inject the lighthouse address that closeTunnel cleared, so the next
+// iteration runs through a fresh handshake against the same harness.
+func BenchmarkHandshake(b *testing.B) {
+	ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version2, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, []string{})
+
+	// Default try_interval is 100ms. The handshake manager schedules handshake1
+	// on its OutboundHandshakeTimer rather than firing immediately on trigger
+	// (the trigger channel only fast-paths static hosts), so a 100ms default
+	// drowns the actual handshake cost. Drop it to 1ms so the bench reflects
+	// the computation, not the wheel cadence.
+	bovr := m{"handshakes": m{"try_interval": "1ms"}}
+	myControl, myVpnIpNet, myUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "me", "10.128.0.1/24", bovr)
+	theirControl, theirVpnIpNet, theirUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "them", "10.128.0.2/24", bovr)
+
+	myControl.InjectLightHouseAddr(theirVpnIpNet[0].Addr(), theirUdpAddr)
+	theirControl.InjectLightHouseAddr(myVpnIpNet[0].Addr(), myUdpAddr)
+
+	myControl.Start()
+	theirControl.Start()
+	defer myControl.Stop()
+	defer theirControl.Stop()
+
+	r := router.NewR(b, myControl, theirControl)
+	r.CancelFlowLogs()
+	r.EnableFanIn()
+
+	trigger := BuildTunUDPPacket(theirVpnIpNet[0].Addr(), 80, myVpnIpNet[0].Addr(), 80, []byte("Hi from me"))
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for n := 0; n < b.N; n++ {
+		myControl.InjectTunPacket(trigger)
+		// RouteForAllUntilTxTun returns the moment the cached packet arrives at
+		// the remote TUN, which is also when both sides are fully established.
+		_ = r.RouteForAllUntilTxTun(theirControl)
+
+		b.StopTimer()
+		// Local-only close removes hostmap state on both sides without putting a
+		// CloseTunnel packet on the wire that we'd then have to drain. The
+		// closeTunnel path also clears learned lighthouse state for the peer
+		// when the last hostinfo for that addr goes away, so we re-inject.
+		myControl.CloseTunnel(theirVpnIpNet[0].Addr(), true)
+		theirControl.CloseTunnel(myVpnIpNet[0].Addr(), true)
+		myControl.InjectLightHouseAddr(theirVpnIpNet[0].Addr(), theirUdpAddr)
+		theirControl.InjectLightHouseAddr(myVpnIpNet[0].Addr(), myUdpAddr)
+		b.StartTimer()
+	}
+}

e2e/handshakes_test.go

@@ -165,7 +165,7 @@ func TestGoodHandshakeNoOverlap(t *testing.T) {
 
 	empty := []byte{}
 	t.Log("do something to cause a handshake")
-	myControl.GetF().SendMessageToVpnAddr(header.Test, header.MessageNone, theirVpnIpNet[0].Addr(), empty, empty, empty)
+	myControl.GetF().SendMessageToVpnAddr(header.Test, header.MessageNone, theirVpnIpNet[0].Addr(), empty, nebula.NewWireBuffer(9001, 0))
 
 	t.Log("Have them consume my stage 0 packet. They have a tunnel now")
 	theirControl.InjectUDPPacket(myControl.GetFromUDP(true))

e2e/leak_test.go

@@ -18,10 +18,14 @@ import (
 // retry mechanism gives the wg.Wait()-driven goroutines a moment to drain
 // before failing the assertion.
 //
-// Intentionally NOT t.Parallel()'d: concurrent tests would have their own
-// goroutines running and trip the assertion.
+// IgnoreCurrent is necessary in the parallelized suite: other tests can
+// leave goroutines mid-shutdown when this one runs (Stop is async, the
+// wg.Wait() drain is not blocking on test return). We're checking that
+// *this* test's setup tears down cleanly, not that the whole suite is
+// idle at this moment. Intentionally NOT t.Parallel()'d for the same
+// reason — concurrent test goroutines would always show up.
 func TestNoGoroutineLeaks(t *testing.T) {
-	defer goleak.VerifyNone(t)
+	defer goleak.VerifyNone(t, goleak.IgnoreCurrent())
 
 	ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version1, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, []string{})
 	myControl, myVpnIpNet, myUdpAddr, _ := newSimpleServer(cert.Version1, ca, caKey, "me", "10.128.0.1/24", nil)

e2e/sshd_test.go

@@ -1,125 +0,0 @@
-//go:build e2e_testing
-// +build e2e_testing
-
-package e2e
-
-import (
-	"crypto/ed25519"
-	"crypto/rand"
-	"encoding/pem"
-	"net"
-	"strings"
-	"testing"
-	"time"
-
-	"github.com/slackhq/nebula/cert"
-	"github.com/slackhq/nebula/cert_test"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-	"golang.org/x/crypto/ssh"
-)
-
-func TestSSHDLifecycle(t *testing.T) {
-	// TestSSHDLifecycle exercises the in-process sshd through several config reloads and a Control.Stop.
-	ca, _, caKey, _ := cert_test.NewTestCaCert(
-		cert.Version1, cert.Curve_CURVE25519,
-		time.Now(), time.Now().Add(10*time.Minute),
-		nil, nil, []string{},
-	)
-
-	hostKeyPEM := generateSSHHostKey(t)
-	clientSigner, clientAuthKey := generateSSHClientKey(t)
-	sshdAddr := allocLoopbackPort(t)
-
-	overrides := m{
-		"sshd": m{
-			"enabled":  true,
-			"listen":   sshdAddr,
-			"host_key": hostKeyPEM,
-			"authorized_users": []m{{
-				"user": "tester",
-				"keys": []string{clientAuthKey},
-			}},
-		},
-	}
-	control, _, _, _ := newSimpleServer(cert.Version1, ca, caKey, "sshd-test", "10.222.0.1/24", overrides)
-	control.Start()
-	t.Cleanup(func() { control.Stop() })
-
-	// sshd binds in a goroutine after Start returns; wait for it.
-	require.Eventually(t, func() bool { return canDial(sshdAddr) }, 2*time.Second, 25*time.Millisecond,
-		"sshd never started listening")
-
-	for i := 1; i <= 3; i++ {
-		out := sshExecReload(t, sshdAddr, clientSigner)
-		assert.Contains(t, out, "Reloading config", "reload cycle %d", i)
-		require.Eventually(t, func() bool { return canDial(sshdAddr) }, 2*time.Second, 25*time.Millisecond,
-			"sshd not listening after reload cycle %d", i)
-	}
-
-	control.Stop()
-	require.Eventually(t, func() bool { return !canDial(sshdAddr) }, 2*time.Second, 25*time.Millisecond,
-		"sshd still listening after Control.Stop")
-}
-
-func canDial(addr string) bool {
-	c, err := net.DialTimeout("tcp", addr, 100*time.Millisecond)
-	if err != nil {
-		return false
-	}
-	_ = c.Close()
-	return true
-}
-
-// allocLoopbackPort grabs an unused TCP port on 127.0.0.1, closes it, and returns the address. There
-// is a small race between releasing the port and the sshd reclaiming it; in practice the OS keeps the
-// port available long enough for the test to bind it.
-func allocLoopbackPort(t *testing.T) string {
-	t.Helper()
-	l, err := net.Listen("tcp", "127.0.0.1:0")
-	require.NoError(t, err)
-	addr := l.Addr().String()
-	require.NoError(t, l.Close())
-	return addr
-}
-
-func generateSSHHostKey(t *testing.T) string {
-	t.Helper()
-	_, priv, err := ed25519.GenerateKey(rand.Reader)
-	require.NoError(t, err)
-	block, err := ssh.MarshalPrivateKey(priv, "nebula-e2e-host")
-	require.NoError(t, err)
-	return string(pem.EncodeToMemory(block))
-}
-
-func generateSSHClientKey(t *testing.T) (ssh.Signer, string) {
-	t.Helper()
-	_, priv, err := ed25519.GenerateKey(rand.Reader)
-	require.NoError(t, err)
-	signer, err := ssh.NewSignerFromKey(priv)
-	require.NoError(t, err)
-	auth := strings.TrimSpace(string(ssh.MarshalAuthorizedKey(signer.PublicKey())))
-	return signer, auth
-}
-
-func sshExecReload(t *testing.T, addr string, signer ssh.Signer) string {
-	t.Helper()
-	cfg := &ssh.ClientConfig{
-		User:            "tester",
-		Auth:            []ssh.AuthMethod{ssh.PublicKeys(signer)},
-		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
-		Timeout:         2 * time.Second,
-	}
-	client, err := ssh.Dial("tcp", addr, cfg)
-	require.NoError(t, err)
-	defer client.Close()
-
-	sess, err := client.NewSession()
-	require.NoError(t, err)
-	defer sess.Close()
-
-	// reload tears the channel down before sending exit-status, so Output returns an error on the
-	// channel close. The output buffer still has whatever the reload callback wrote before that.
-	out, _ := sess.Output("reload")
-	return string(out)
-}

ecn_inner_test.go

@@ -1,125 +0,0 @@
-package nebula
-
-import (
-	"io"
-	"log/slog"
-	"testing"
-)
-
-func TestInnerECN(t *testing.T) {
-	cases := []struct {
-		name string
-		pkt  []byte
-		want byte
-	}{
-		{"empty", nil, 0},
-		{"v4_NotECT", v4WithToS(0x00), 0x00},
-		{"v4_ECT0", v4WithToS(0x02), 0x02},
-		{"v4_ECT1", v4WithToS(0x01), 0x01},
-		{"v4_CE", v4WithToS(0x03), 0x03},
-		{"v4_DSCP_then_NotECT", v4WithToS(0x88 | 0x00), 0x00},
-		{"v4_DSCP_then_CE", v4WithToS(0x88 | 0x03), 0x03},
-		{"v6_NotECT", v6WithTC(0x00), 0x00},
-		{"v6_ECT0", v6WithTC(0x02), 0x02},
-		{"v6_CE", v6WithTC(0x03), 0x03},
-		{"v6_DSCP_then_CE", v6WithTC(0x88 | 0x03), 0x03},
-		{"unknown_version", []byte{0xa5, 0xff}, 0},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			got := innerECN(c.pkt)
-			if got != c.want {
-				t.Errorf("innerECN=0x%02x want 0x%02x", got, c.want)
-			}
-		})
-	}
-}
-
-// v4WithToS returns a 2-byte slice tall enough for innerECN: byte 0 carries
-// version=4 in the high nibble, byte 1 is the full ToS so we exercise both
-// the DSCP and ECN portions through the byte 1 mask.
-func v4WithToS(tos byte) []byte {
-	return []byte{0x45, tos}
-}
-
-// v6WithTC builds a 2-byte slice that places a known traffic class value
-// across bytes 0 (high nibble of TC) and 1 (low nibble of TC). innerECN
-// extracts ECN as (b[1]>>4)&0x03, which corresponds to TC[1:0].
-func v6WithTC(tc byte) []byte {
-	return []byte{0x60 | (tc>>4)&0x0f, (tc & 0x0f) << 4}
-}
-
-func TestApplyOuterECN(t *testing.T) {
-	silent := slog.New(slog.NewTextHandler(io.Discard, nil))
-	hi := &HostInfo{}
-
-	// Build a v4 packet helper with a given inner ECN field.
-	v4 := func(innerECN byte) []byte {
-		// 20-byte minimal IPv4 header with ToS = innerECN (DSCP zeroed).
-		return []byte{
-			0x45, innerECN, 0, 28,
-			0, 0, 0x40, 0,
-			64, 6, 0, 0,
-			10, 0, 0, 1,
-			10, 0, 0, 2,
-		}
-	}
-	// Build a v6 packet helper with a given inner ECN field. ECN occupies
-	// TC[1:0] which sit at byte 1 mask 0x30.
-	v6 := func(innerECN byte) []byte {
-		// 40-byte minimal IPv6 header with TC[1:0] = innerECN.
-		pkt := make([]byte, 40)
-		pkt[0] = 0x60                   // version=6, TC[7:4]=0
-		pkt[1] = (innerECN & 0x03) << 4 // TC[3:0]: low 2 bits = ECN, top 2 = DSCP-low (0)
-		return pkt
-	}
-
-	type cell struct {
-		outer    byte
-		inner    byte
-		wantECN  byte
-		wantSame bool // expect inner unchanged (true => verify the byte didn't move)
-	}
-
-	// RFC 6040 normal-mode combine table. Only outer==CE causes mutation.
-	table := []cell{
-		{ecnNotECT, ecnNotECT, ecnNotECT, true},
-		{ecnNotECT, ecnECT0, ecnECT0, true},
-		{ecnNotECT, ecnECT1, ecnECT1, true},
-		{ecnNotECT, ecnCE, ecnCE, true},
-
-		{ecnECT0, ecnNotECT, ecnNotECT, true},
-		{ecnECT0, ecnECT0, ecnECT0, true},
-		{ecnECT0, ecnECT1, ecnECT1, true},
-		{ecnECT0, ecnCE, ecnCE, true},
-
-		{ecnECT1, ecnNotECT, ecnNotECT, true},
-		{ecnECT1, ecnECT0, ecnECT0, true},
-		{ecnECT1, ecnECT1, ecnECT1, true},
-		{ecnECT1, ecnCE, ecnCE, true},
-
-		{ecnCE, ecnNotECT, ecnNotECT, true}, // legacy: log, leave alone
-		{ecnCE, ecnECT0, ecnCE, false},      // CE folded in
-		{ecnCE, ecnECT1, ecnCE, false},
-		{ecnCE, ecnCE, ecnCE, true},
-	}
-
-	for _, c := range table {
-		t.Run("v4", func(t *testing.T) {
-			pkt := v4(c.inner)
-			applyOuterECN(pkt, c.outer, hi, silent)
-			got := pkt[1] & 0x03
-			if got != c.wantECN {
-				t.Errorf("v4 outer=0x%02x inner=0x%02x: got 0x%02x want 0x%02x", c.outer, c.inner, got, c.wantECN)
-			}
-		})
-		t.Run("v6", func(t *testing.T) {
-			pkt := v6(c.inner)
-			applyOuterECN(pkt, c.outer, hi, silent)
-			got := (pkt[1] >> 4) & 0x03
-			if got != c.wantECN {
-				t.Errorf("v6 outer=0x%02x inner=0x%02x: got 0x%02x want 0x%02x", c.outer, c.inner, got, c.wantECN)
-			}
-		})
-	}
-}

examples/config.yml

@@ -138,14 +138,6 @@ listen:
   # max, net.core.rmem_max and net.core.wmem_max
   #read_buffer: 10485760
   #write_buffer: 10485760
-
-  # On Windows only
-  # When true, Nebula installs a WFP (Windows Filtering Platform) PERMIT filter scoped to UDP at the listener port.
-  # WFP sits below Windows Defender Firewall, so this lets peer handshakes reach Nebula's outside socket regardless
-  # of WDF's inbound rules.
-  # Default true; set to false to leave WDF in charge of inbound decisions on the listener port. Not reloadable.
-  #windows_bypass_wdf: true
-
   # By default, Nebula replies to packets it has no tunnel for with a "recv_error" packet. This packet helps speed up reconnection
   # in the case that Nebula on either side did not shut down cleanly. This response can be abused as a way to discover if Nebula is running
   # on a host though. This option lets you configure if you want to send "recv_error" packets always, never, or only to private network remotes.
@@ -171,21 +163,17 @@ listen:
 
 punchy:
   # Continues to punch inbound/outbound at a regular interval to avoid expiration of firewall nat mappings
-  # This setting is reloadable.
   punch: true
 
   # respond means that a node you are trying to reach will connect back out to you if your hole punching fails
   # this is extremely useful if one node is behind a difficult nat, such as a symmetric NAT
   # Default is false
-  # This setting is reloadable.
   #respond: true
 
   # delays a punch response for misbehaving NATs, default is 1 second.
-  # This setting is reloadable.
   #delay: 1s
 
   # set the delay before attempting punchy.respond. Default is 5 seconds. respond must be true to take effect.
-  # This setting is reloadable.
   #respond_delay: 5s
 
 # Cipher allows you to choose between the available ciphers for your network. Options are chachapoly or aes
@@ -294,24 +282,6 @@ tun:
     #  metric: 100
     #  install: true
 
-  # On Windows only, sets the network category of the nebula interface. Without this, Windows often
-  # leaves the network as "Unidentified" and treats it as Public, which makes the host firewall more
-  # restrictive than you usually want for an overlay between trusted peers. Valid values:
-  #   private             - treat the nebula network as a private/trusted network (default)
-  #   public              - treat it as a public/untrusted network
-  #   domain              - treat it as a domain-authenticated network
-  #   unset               - leave whatever Windows decided alone
-  # Not reloadable.
-  #network_category: private
-
-  # On Windows only
-  # When true, Nebula installs a WFP (Windows Filtering Platform) PERMIT filter scoped to the nebula adapter LUID.
-  # WFP sits below Windows Defender Firewall, so this lets inbound traffic through regardless of WDF rules.
-  # Filters are auto-removed when the adapter goes away.
-  # See listen.windows_bypass_wdf for the matching control over inbound to nebula's outside UDP listener.
-  # Default true; set to false to leave WDF in charge of inbound decisions on the nebula interface. Not reloadable.
-  #windows_bypass_wdf: true
-
   # On linux only, set to true to manage unsafe routes directly on the system route table with gateway routes instead of
   # in nebula configuration files. Default false, not reloadable.
   #use_system_route_table: false

firewall.go

@@ -80,8 +80,8 @@ type firewallMetrics struct {
 type FirewallConntrack struct {
 	sync.Mutex
 
-	Conns      map[firewall.PacketKey]*conn
-	TimerWheel *TimerWheel[firewall.PacketKey]
+	Conns      map[firewall.Packet]*conn
+	TimerWheel *TimerWheel[firewall.Packet]
 }
 
 // FirewallTable is the entry point for a rule, the evaluation order is:
@@ -166,8 +166,8 @@ func NewFirewall(l *slog.Logger, tcpTimeout, UDPTimeout, defaultTimeout time.Dur
 
 	return &Firewall{
 		Conntrack: &FirewallConntrack{
-			Conns:      make(map[firewall.PacketKey]*conn),
-			TimerWheel: NewTimerWheel[firewall.PacketKey](tmin, tmax),
+			Conns:      make(map[firewall.Packet]*conn),
+			TimerWheel: NewTimerWheel[firewall.Packet](tmin, tmax),
 		},
 		InRules:           newFirewallTable(),
 		OutRules:          newFirewallTable(),
@@ -422,27 +422,12 @@ var ErrNoMatchingRule = errors.New("no matching rule in firewall table")
 
 // Drop returns an error if the packet should be dropped, explaining why. It
 // returns nil if the packet should not be dropped.
-//
-// key is the dense conntrack key — used as-is for the inConns fast path
-// without touching fp at all. fp is the rich Packet form rule matching
-// needs (CIDR lookups, family checks); on the conntrack-miss slow path
-// Drop ensures fp is hydrated from key (idempotent if the caller already
-// filled fp). On accept-via-conntrack the caller's fp is left untouched.
-func (f *Firewall) Drop(key firewall.PacketKey, fp *firewall.Packet, incoming bool, h *HostInfo, caPool *cert.CAPool, localCache firewall.ConntrackCache) error {
-	// Check if we spoke to this tuple, if we did then allow this packet.
-	// Hot path: only the dense key is touched.
-	if f.inConns(key, h, caPool, localCache) {
+func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *cert.CAPool, localCache firewall.ConntrackCache) error {
+	// Check if we spoke to this tuple, if we did then allow this packet
+	if f.inConns(fp, h, caPool, localCache) {
 		return nil
 	}
 
-	// Conntrack miss → rule matching needs the rich Packet form. Hydrate
-	// from the key if the caller passed a zero-valued fp (the inbound path
-	// after batch.ParsePacket). Outbound callers Hydrate themselves and
-	// skip this hop.
-	if !fp.LocalAddr.IsValid() {
-		key.Hydrate(fp)
-	}
-
 	// Make sure remote address matches nebula certificate, and determine how to treat it
 	if h.networks == nil {
 		// Simple case: Certificate has one address and no unsafe networks
@@ -482,13 +467,13 @@ func (f *Firewall) Drop(key firewall.PacketKey, fp *firewall.Packet, incoming bo
 	}
 
 	// We now know which firewall table to check against
-	if !table.match(*fp, incoming, h.ConnectionState.peerCert, caPool) {
+	if !table.match(fp, incoming, h.ConnectionState.peerCert, caPool) {
 		f.metrics(incoming).droppedNoRule.Inc(1)
 		return ErrNoMatchingRule
 	}
 
 	// We always want to conntrack since it is a faster operation
-	f.addConn(key, fp.Protocol, incoming)
+	f.addConn(fp, incoming)
 
 	return nil
 }
@@ -517,9 +502,9 @@ func (f *Firewall) EmitStats() {
 	metrics.GetOrRegisterGauge("firewall.rules.hash", nil).Update(int64(f.GetRuleHashFNV()))
 }
 
-func (f *Firewall) inConns(key firewall.PacketKey, h *HostInfo, caPool *cert.CAPool, localCache firewall.ConntrackCache) bool {
+func (f *Firewall) inConns(fp firewall.Packet, h *HostInfo, caPool *cert.CAPool, localCache firewall.ConntrackCache) bool {
 	if localCache != nil {
-		if _, ok := localCache[key]; ok {
+		if _, ok := localCache[fp]; ok {
 			return true
 		}
 	}
@@ -532,7 +517,7 @@ func (f *Firewall) inConns(key firewall.PacketKey, h *HostInfo, caPool *cert.CAP
 		f.evict(ep)
 	}
 
-	c, ok := conntrack.Conns[key]
+	c, ok := conntrack.Conns[fp]
 
 	if !ok {
 		conntrack.Unlock()
@@ -541,11 +526,7 @@ func (f *Firewall) inConns(key firewall.PacketKey, h *HostInfo, caPool *cert.CAP
 
 	if c.rulesVersion != f.rulesVersion {
 		// This conntrack entry was for an older rule set, validate
-		// it still passes with the current rule set. Rule matching needs
-		// the rich Packet form, so hydrate from key.
-		var fp firewall.Packet
-		key.Hydrate(&fp)
-
+		// it still passes with the current rule set
 		table := f.OutRules
 		if c.incoming {
 			table = f.InRules
@@ -561,7 +542,7 @@ func (f *Firewall) inConns(key firewall.PacketKey, h *HostInfo, caPool *cert.CAP
 					"oldRulesVersion", c.rulesVersion,
 				)
 			}
-			delete(conntrack.Conns, key)
+			delete(conntrack.Conns, fp)
 			conntrack.Unlock()
 			return false
 		}
@@ -578,7 +559,7 @@ func (f *Firewall) inConns(key firewall.PacketKey, h *HostInfo, caPool *cert.CAP
 		c.rulesVersion = f.rulesVersion
 	}
 
-	switch key.Protocol {
+	switch fp.Protocol {
 	case firewall.ProtoTCP:
 		c.Expires = time.Now().Add(f.TCPTimeout)
 	case firewall.ProtoUDP:
@@ -590,17 +571,17 @@ func (f *Firewall) inConns(key firewall.PacketKey, h *HostInfo, caPool *cert.CAP
 	conntrack.Unlock()
 
 	if localCache != nil {
-		localCache[key] = struct{}{}
+		localCache[fp] = struct{}{}
 	}
 
 	return true
 }
 
-func (f *Firewall) addConn(key firewall.PacketKey, protocol uint8, incoming bool) {
+func (f *Firewall) addConn(fp firewall.Packet, incoming bool) {
 	var timeout time.Duration
 	c := &conn{}
 
-	switch protocol {
+	switch fp.Protocol {
 	case firewall.ProtoTCP:
 		timeout = f.TCPTimeout
 	case firewall.ProtoUDP:
@@ -611,9 +592,9 @@ func (f *Firewall) addConn(key firewall.PacketKey, protocol uint8, incoming bool
 
 	conntrack := f.Conntrack
 	conntrack.Lock()
-	if _, ok := conntrack.Conns[key]; !ok {
+	if _, ok := conntrack.Conns[fp]; !ok {
 		conntrack.TimerWheel.Advance(time.Now())
-		conntrack.TimerWheel.Add(key, timeout)
+		conntrack.TimerWheel.Add(fp, timeout)
 	}
 
 	// Record which rulesVersion allowed this connection, so we can retest after
@@ -621,16 +602,16 @@ func (f *Firewall) addConn(key firewall.PacketKey, protocol uint8, incoming bool
 	c.incoming = incoming
 	c.rulesVersion = f.rulesVersion
 	c.Expires = time.Now().Add(timeout)
-	conntrack.Conns[key] = c
+	conntrack.Conns[fp] = c
 	conntrack.Unlock()
 }
 
 // Evict checks if a conntrack entry has expired, if so it is removed, if not it is re-added to the wheel
 // Caller must own the connMutex lock!
-func (f *Firewall) evict(key firewall.PacketKey) {
+func (f *Firewall) evict(p firewall.Packet) {
 	// Are we still tracking this conn?
 	conntrack := f.Conntrack
-	t, ok := conntrack.Conns[key]
+	t, ok := conntrack.Conns[p]
 	if !ok {
 		return
 	}
@@ -640,12 +621,12 @@ func (f *Firewall) evict(key firewall.PacketKey) {
 	// Timeout is in the future, re-add the timer
 	if newT > 0 {
 		conntrack.TimerWheel.Advance(time.Now())
-		conntrack.TimerWheel.Add(key, newT)
+		conntrack.TimerWheel.Add(p, newT)
 		return
 	}
 
 	// This conn is done
-	delete(conntrack.Conns, key)
+	delete(conntrack.Conns, p)
 }
 
 func (ft *FirewallTable) match(p firewall.Packet, incoming bool, c *cert.CachedCertificate, caPool *cert.CAPool) bool {

firewall/cache.go

@@ -5,15 +5,11 @@ import (
 	"log/slog"
 	"sync/atomic"
 	"time"
-
-	"github.com/slackhq/nebula/logging"
 )
 
 // ConntrackCache is used as a local routine cache to know if a given flow
-// has been seen in the conntrack table. Keyed on PacketKey (dense form)
-// rather than Packet so the lookup hashes raw bytes instead of the
-// unique.Handle each netip.Addr in Packet carries.
-type ConntrackCache map[PacketKey]struct{}
+// has been seen in the conntrack table.
+type ConntrackCache map[Packet]struct{}
 
 type ConntrackCacheTicker struct {
 	cacheV    uint64
@@ -60,8 +56,8 @@ func (c *ConntrackCacheTicker) Get() ConntrackCache {
 	if tick := c.cacheTick.Load(); tick != c.cacheV {
 		c.cacheV = tick
 		if ll := len(c.cache); ll > 0 {
-			if c.l.Enabled(context.Background(), logging.LevelTrace) {
-				c.l.Log(context.Background(), logging.LevelTrace, "resetting conntrack cache", "len", ll)
+			if c.l.Enabled(context.Background(), slog.LevelDebug) {
+				c.l.Debug("resetting conntrack cache", "len", ll)
 			}
 			c.cache = make(ConntrackCache, ll)
 		}

firewall/cache_test.go

@@ -6,7 +6,6 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/slackhq/nebula/logging"
 	"github.com/slackhq/nebula/test"
 	"github.com/stretchr/testify/assert"
 )
@@ -23,7 +22,7 @@ func newFixedTicker(t *testing.T, l *slog.Logger, cacheLen int) *ConntrackCacheT
 		cache: make(ConntrackCache, cacheLen),
 	}
 	for i := 0; i < cacheLen; i++ {
-		c.cache[PacketKey{LocalPort: uint16(i) + 1}] = struct{}{}
+		c.cache[Packet{LocalPort: uint16(i) + 1}] = struct{}{}
 	}
 	c.cacheTick.Store(1) // cacheV starts at 0, so Get() takes the reset path
 	return c
@@ -31,27 +30,27 @@ func newFixedTicker(t *testing.T, l *slog.Logger, cacheLen int) *ConntrackCacheT
 
 func TestConntrackCacheTicker_Get_TextFormat(t *testing.T) {
 	buf := &bytes.Buffer{}
-	l := test.NewLoggerWithOutputAndLevel(buf, logging.LevelTrace)
+	l := test.NewLoggerWithOutputAndLevel(buf, slog.LevelDebug)
 
 	c := newFixedTicker(t, l, 3)
 	c.Get()
 
-	assert.Equal(t, "level=DEBUG-4 msg=\"resetting conntrack cache\" len=3\n", buf.String())
+	assert.Equal(t, "level=DEBUG msg=\"resetting conntrack cache\" len=3\n", buf.String())
 }
 
 func TestConntrackCacheTicker_Get_JSONFormat(t *testing.T) {
 	buf := &bytes.Buffer{}
-	l := test.NewJSONLoggerWithOutput(buf, logging.LevelTrace)
+	l := test.NewJSONLoggerWithOutput(buf, slog.LevelDebug)
 
 	c := newFixedTicker(t, l, 2)
 	c.Get()
 
-	assert.JSONEq(t, `{"level":"DEBUG-4","msg":"resetting conntrack cache","len":2}`, strings.TrimSpace(buf.String()))
+	assert.JSONEq(t, `{"level":"DEBUG","msg":"resetting conntrack cache","len":2}`, strings.TrimSpace(buf.String()))
 }
 
-func TestConntrackCacheTicker_Get_QuietBelowTrace(t *testing.T) {
+func TestConntrackCacheTicker_Get_QuietBelowDebug(t *testing.T) {
 	buf := &bytes.Buffer{}
-	l := test.NewLoggerWithOutputAndLevel(buf, slog.LevelDebug)
+	l := test.NewLoggerWithOutputAndLevel(buf, slog.LevelInfo)
 
 	c := newFixedTicker(t, l, 5)
 	c.Get()
@@ -61,7 +60,7 @@ func TestConntrackCacheTicker_Get_QuietBelowTrace(t *testing.T) {
 
 func TestConntrackCacheTicker_Get_QuietWhenCacheEmpty(t *testing.T) {
 	buf := &bytes.Buffer{}
-	l := test.NewLoggerWithOutputAndLevel(buf, logging.LevelTrace)
+	l := test.NewLoggerWithOutputAndLevel(buf, slog.LevelDebug)
 
 	c := newFixedTicker(t, l, 0)
 	c.Get()

firewall/packet.go

@@ -19,25 +19,6 @@ const (
 	PortFragment = -1 // Special value for matching `port: fragment`
 )
 
-// PacketKey is the firewall's conntrack and ConntrackCache map key — the
-// dense form of the 5-tuple plus the protocol and fragment flag the
-// firewall actually discriminates flows on. Kept separate from Packet so
-// the conntrack-hit fast path doesn't pay for hashing the unique.Handle
-// each netip.Addr carries, and so the inbound parser can skip the
-// AddrFrom4/AddrFrom16 calls until rule matching actually needs them.
-//
-// Superset of the coalescer's flowKey shape (same 5-tuple, just in
-// Local/Remote orientation rather than wire src/dst).
-type PacketKey struct {
-	LocalAddr  [16]byte
-	RemoteAddr [16]byte
-	LocalPort  uint16
-	RemotePort uint16
-	IsV6       bool
-	Protocol   uint8
-	Fragment   bool
-}
-
 type Packet struct {
 	LocalAddr  netip.Addr
 	RemoteAddr netip.Addr
@@ -50,61 +31,6 @@ type Packet struct {
 	Fragment   bool
 }
 
-// Key derives a PacketKey from a populated Packet. Used by the few code
-// paths that have a Packet but no Key in hand (e.g. tests). Both inbound
-// and outbound production parsers write straight into a PacketKey via
-// batch.ParsePacket, so this function is rarely on the hot path.
-func (fp *Packet) Key() PacketKey {
-	k := PacketKey{
-		Protocol: fp.Protocol,
-		Fragment: fp.Fragment,
-	}
-	k.LocalPort = fp.LocalPort
-	k.RemotePort = fp.RemotePort
-	k.IsV6 = !fp.LocalAddr.Is4()
-	if k.IsV6 {
-		k.LocalAddr = fp.LocalAddr.As16()
-		k.RemoteAddr = fp.RemoteAddr.As16()
-	} else {
-		v4 := fp.LocalAddr.As4()
-		copy(k.LocalAddr[:4], v4[:])
-		v4 = fp.RemoteAddr.As4()
-		copy(k.RemoteAddr[:4], v4[:])
-	}
-	return k
-}
-
-// Hydrate fills fp's netip.Addr fields and copies the rest from k. Called
-// by the firewall slow path when conntrack misses and rule matching needs
-// the rich Packet form (CIDR lookups, family checks). The fast path skips
-// this entirely.
-func (k *PacketKey) Hydrate(fp *Packet) {
-	fp.LocalPort = k.LocalPort
-	fp.RemotePort = k.RemotePort
-	fp.Protocol = k.Protocol
-	fp.Fragment = k.Fragment
-	if k.IsV6 {
-		fp.LocalAddr = netip.AddrFrom16(k.LocalAddr)
-		fp.RemoteAddr = netip.AddrFrom16(k.RemoteAddr)
-	} else {
-		var v4 [4]byte
-		copy(v4[:], k.LocalAddr[:4])
-		fp.LocalAddr = netip.AddrFrom4(v4)
-		copy(v4[:], k.RemoteAddr[:4])
-		fp.RemoteAddr = netip.AddrFrom4(v4)
-	}
-}
-
-func (k *PacketKey) GetRemoteAddr() netip.Addr {
-	if k.IsV6 {
-		return netip.AddrFrom16(k.RemoteAddr)
-	} else {
-		var v4 [4]byte
-		copy(v4[:], k.RemoteAddr[:4])
-		return netip.AddrFrom4(v4)
-	}
-}
-
 func (fp *Packet) Copy() *Packet {
 	return &Packet{
 		LocalAddr:  fp.LocalAddr,

firewall_test.go

@@ -211,44 +211,44 @@ func TestFirewall_Drop(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// Drop outbound
-	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p.Key(), &p, false, &h, cp, nil))
+	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p, false, &h, cp, nil))
 	// Allow inbound
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 	// Allow outbound because conntrack
-	require.NoError(t, fw.Drop(p.Key(), &p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
 
 	// test remote mismatch
 	oldRemote := p.RemoteAddr
 	p.RemoteAddr = netip.MustParseAddr("1.2.3.10")
-	assert.Equal(t, fw.Drop(p.Key(), &p, false, &h, cp, nil), ErrInvalidRemoteIP)
+	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrInvalidRemoteIP)
 	p.RemoteAddr = oldRemote
 
 	// ensure signer doesn't get in the way of group checks
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum-bad"))
-	assert.Equal(t, fw.Drop(p.Key(), &p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caSha doesn't drop on match
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum-bad"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum"))
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 
 	// ensure ca name doesn't get in the way of group checks
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good-bad", ""))
-	assert.Equal(t, fw.Drop(p.Key(), &p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caName doesn't drop on match
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good-bad", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good", ""))
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 }
 
 func TestFirewall_DropV6(t *testing.T) {
@@ -289,44 +289,44 @@ func TestFirewall_DropV6(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// Drop outbound
-	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p.Key(), &p, false, &h, cp, nil))
+	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p, false, &h, cp, nil))
 	// Allow inbound
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 	// Allow outbound because conntrack
-	require.NoError(t, fw.Drop(p.Key(), &p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
 
 	// test remote mismatch
 	oldRemote := p.RemoteAddr
 	p.RemoteAddr = netip.MustParseAddr("fd12::56")
-	assert.Equal(t, fw.Drop(p.Key(), &p, false, &h, cp, nil), ErrInvalidRemoteIP)
+	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrInvalidRemoteIP)
 	p.RemoteAddr = oldRemote
 
 	// ensure signer doesn't get in the way of group checks
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum-bad"))
-	assert.Equal(t, fw.Drop(p.Key(), &p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caSha doesn't drop on match
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum-bad"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum"))
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 
 	// ensure ca name doesn't get in the way of group checks
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good-bad", ""))
-	assert.Equal(t, fw.Drop(p.Key(), &p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caName doesn't drop on match
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good-bad", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good", ""))
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 }
 
 func BenchmarkFirewallTable_match(b *testing.B) {
@@ -533,10 +533,10 @@ func TestFirewall_Drop2(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// h1/c1 lacks the proper groups
-	require.ErrorIs(t, fw.Drop(p.Key(), &p, true, &h1, cp, nil), ErrNoMatchingRule)
+	require.ErrorIs(t, fw.Drop(p, true, &h1, cp, nil), ErrNoMatchingRule)
 	// c has the proper groups
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 }
 
 func TestFirewall_Drop3(t *testing.T) {
@@ -613,18 +613,18 @@ func TestFirewall_Drop3(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// c1 should pass because host match
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h1, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h1, cp, nil))
 	// c2 should pass because ca sha match
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h2, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h2, cp, nil))
 	// c3 should fail because no match
 	resetConntrack(fw)
-	assert.Equal(t, fw.Drop(p.Key(), &p, true, &h3, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, true, &h3, cp, nil), ErrNoMatchingRule)
 
 	// Test a remote address match
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 1, 1, []string{}, "", "1.2.3.4/24", "", "", ""))
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h1, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h1, cp, nil))
 }
 
 func TestFirewall_Drop3V6(t *testing.T) {
@@ -661,7 +661,7 @@ func TestFirewall_Drop3V6(t *testing.T) {
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	cp := cert.NewCAPool()
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 1, 1, []string{}, "", "fd12::34/120", "", "", ""))
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 }
 
 func TestFirewall_DropConntrackReload(t *testing.T) {
@@ -702,12 +702,12 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// Drop outbound
-	assert.Equal(t, fw.Drop(p.Key(), &p, false, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrNoMatchingRule)
 	// Allow inbound
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p.Key(), &p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
 	// Allow outbound because conntrack
-	require.NoError(t, fw.Drop(p.Key(), &p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
 
 	oldFw := fw
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
@@ -716,7 +716,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	fw.rulesVersion = oldFw.rulesVersion + 1
 
 	// Allow outbound because conntrack and new rules allow port 10
-	require.NoError(t, fw.Drop(p.Key(), &p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
 
 	oldFw = fw
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
@@ -725,7 +725,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	fw.rulesVersion = oldFw.rulesVersion + 1
 
 	// Drop outbound because conntrack doesn't match new ruleset
-	assert.Equal(t, fw.Drop(p.Key(), &p, false, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrNoMatchingRule)
 }
 
 func TestFirewall_ICMPPortBehavior(t *testing.T) {
@@ -770,12 +770,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0
 			p.RemotePort = 0
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(p.Key(), p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(p.Key(), p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
 		})
 
 		t.Run("nonzero ports", func(t *testing.T) {
@@ -783,12 +783,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0xabcd
 			p.RemotePort = 0x1234
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(p.Key(), p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(p.Key(), p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
 		})
 	})
 
@@ -800,12 +800,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0
 			p.RemotePort = 0
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			assert.Equal(t, fw.Drop(p.Key(), p, true, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, true, &h, cp, nil), ErrNoMatchingRule)
 			//now also allow outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 
 		t.Run("nonzero ports, still blocked", func(t *testing.T) {
@@ -813,12 +813,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0xabcd
 			p.RemotePort = 0x1234
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			assert.Equal(t, fw.Drop(p.Key(), p, true, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, true, &h, cp, nil), ErrNoMatchingRule)
 			//now also allow outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 
 		t.Run("nonzero, matching ports, still blocked", func(t *testing.T) {
@@ -826,12 +826,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 80
 			p.RemotePort = 80
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			assert.Equal(t, fw.Drop(p.Key(), p, true, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, true, &h, cp, nil), ErrNoMatchingRule)
 			//now also allow outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 	})
 	t.Run("Any proto, any port", func(t *testing.T) {
@@ -843,12 +843,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0
 			p.RemotePort = 0
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(p.Key(), p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(p.Key(), p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
 		})
 
 		t.Run("nonzero ports, allowed", func(t *testing.T) {
@@ -857,15 +857,15 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0xabcd
 			p.RemotePort = 0x1234
 			// Drop outbound
-			assert.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(p.Key(), p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(p.Key(), p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
 			//different ID is blocked
 			p.RemotePort++
-			require.Equal(t, fw.Drop(p.Key(), p, false, &h, cp, nil), ErrNoMatchingRule)
+			require.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 	})
 
@@ -913,7 +913,7 @@ func TestFirewall_DropIPSpoofing(t *testing.T) {
 		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}
-	assert.Equal(t, fw.Drop(p.Key(), &p, true, &h1, cp, nil), ErrInvalidRemoteIP)
+	assert.Equal(t, fw.Drop(p, true, &h1, cp, nil), ErrInvalidRemoteIP)
 }
 
 func BenchmarkLookup(b *testing.B) {
@@ -1327,7 +1327,7 @@ func (c *testcase) Test(t *testing.T, fw *Firewall) {
 	t.Helper()
 	cp := cert.NewCAPool()
 	resetConntrack(fw)
-	err := fw.Drop(c.p.Key(), &c.p, true, c.h, cp, nil)
+	err := fw.Drop(c.p, true, c.h, cp, nil)
 	if c.err == nil {
 		require.NoError(t, err, "failed to not drop remote address %s", c.p.RemoteAddr)
 	} else {
@@ -1519,6 +1519,6 @@ func (mf *mockFirewall) AddRule(incoming bool, proto uint8, startPort int32, end
 
 func resetConntrack(fw *Firewall) {
 	fw.Conntrack.Lock()
-	fw.Conntrack.Conns = map[firewall.PacketKey]*conn{}
+	fw.Conntrack.Conns = map[firewall.Packet]*conn{}
 	fw.Conntrack.Unlock()
 }

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/armon/go-radix v1.0.0
 	github.com/cyberdelia/go-metrics-graphite v0.0.0-20161219230853-39f87cc3b432
 	github.com/flynn/noise v1.1.0
-	github.com/gaissmai/bart v0.26.1
+	github.com/gaissmai/bart v0.26.0
 	github.com/gogo/protobuf v1.3.2
 	github.com/google/gopacket v1.1.19
 	github.com/kardianos/service v1.2.4
@@ -26,7 +26,7 @@ require (
 	go.yaml.in/yaml/v3 v3.0.4
 	golang.org/x/crypto v0.50.0
 	golang.org/x/exp v0.0.0-20230725093048-515e97ebf090
-	golang.org/x/net v0.53.0
+	golang.org/x/net v0.52.0
 	golang.org/x/sync v0.20.0
 	golang.org/x/sys v0.43.0
 	golang.org/x/term v0.42.0
@@ -43,7 +43,6 @@ require (
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/google/btree v1.1.2 // indirect
-	github.com/guptarohit/asciigraph v0.9.0 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect

go.sum

@@ -26,8 +26,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/flynn/noise v1.1.0 h1:KjPQoQCEFdZDiP03phOvGi11+SVVhBG2wOWAorLsstg=
 github.com/flynn/noise v1.1.0/go.mod h1:xbMo+0i6+IGbYdJhF31t2eR1BIU0CYc12+BNAKwUTag=
-github.com/gaissmai/bart v0.26.1 h1:+w4rnLGNlA2GDVn382Tfe3jOsK5vOr5n4KmigJ9lbTo=
-github.com/gaissmai/bart v0.26.1/go.mod h1:GREWQfTLRWz/c5FTOsIw+KkscuFkIV5t8Rp7Nd1Td5c=
+github.com/gaissmai/bart v0.26.0 h1:xOZ57E9hJLBiQaSyeZa9wgWhGuzfGACgqp4BE77OkO0=
+github.com/gaissmai/bart v0.26.0/go.mod h1:GREWQfTLRWz/c5FTOsIw+KkscuFkIV5t8Rp7Nd1Td5c=
 github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
 github.com/go-kit/kit v0.9.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
 github.com/go-kit/log v0.1.0/go.mod h1:zbhenjAZHb184qTLMA9ZjW7ThYL0H2mk7Q6pNt4vbaY=
@@ -60,8 +60,6 @@ github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
 github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
-github.com/guptarohit/asciigraph v0.9.0 h1:MvCSRRVkT2XvU1IO6n92o7l7zqx1DiFaoszOUZQztbY=
-github.com/guptarohit/asciigraph v0.9.0/go.mod h1:dYl5wwK4gNsnFf9Zp+l06rFiDZ5YtXM6x7SRWZ3KGag=
 github.com/jpillora/backoff v1.0.0/go.mod h1:J/6gKK9jxlEcS3zixgDgUAsiuZ7yrSoa/FX5e0EB2j4=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
 github.com/json-iterator/go v1.1.10/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
@@ -184,8 +182,8 @@ golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-golang.org/x/net v0.53.0 h1:d+qAbo5L0orcWAr0a9JweQpjXF19LMXJE8Ey7hwOdUA=
-golang.org/x/net v0.53.0/go.mod h1:JvMuJH7rrdiCfbeHoo3fCQU24Lf5JJwT9W3sJFulfgs=
+golang.org/x/net v0.52.0 h1:He/TN1l0e4mmR3QqHMT2Xab3Aj3L9qjbhRm78/6jrW0=
+golang.org/x/net v0.52.0/go.mod h1:R1MAz7uMZxVMualyPXb+VaqGSa3LIaUqk0eEt3w36Sw=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

handshake/machine.go

@@ -31,7 +31,6 @@ type CertVerifier func(cert.Certificate) (*cert.CachedCertificate, error)
 type Result struct {
 	EKey          *noise.CipherState
 	DKey          *noise.CipherState
-	Cipher        noise.CipherFunc // identifies which post-handshake CipherState the data plane should wrap EKey/DKey in
 	MyCert        cert.Certificate
 	RemoteCert    *cert.CachedCertificate
 	RemoteIndex   uint32
@@ -106,7 +105,6 @@ func NewMachine(
 		myVersion:  version,
 		result: &Result{
 			Initiator: initiator,
-			Cipher:    cred.cipherSuite,
 		},
 	}, nil
 }

handshake_manager.go

@@ -971,12 +971,11 @@ func (hm *HandshakeManager) continueHandshake(via ViaSender, hh *HandshakeHostIn
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			hostinfo.logger(f.l).Debug("Sending stored packets", "count", len(hh.packetStore))
 		}
-		nb := make([]byte, 12, 12)
-		out := make([]byte, mtu)
+		buf := f.bufAlloc.Acquire()
 		for _, cp := range hh.packetStore {
-			//todo use a sendbatcher
-			cp.callback(cp.messageType, cp.messageSubType, hostinfo, cp.packet, nb, out)
+			cp.callback(cp.messageType, cp.messageSubType, hostinfo, cp.packet, buf)
 		}
+		f.bufAlloc.Release(buf)
 		f.cachedPacketMetrics.sent.Inc(int64(len(hh.packetStore)))
 	}
 
@@ -1086,7 +1085,9 @@ func (hm *HandshakeManager) sendHandshakeResponse(via ViaSender, msg []byte, hos
 		// We received a valid handshake on this relay, so make sure the relay
 		// state reflects that, in case it had been marked Disestablished.
 		via.relayHI.relayState.UpdateRelayForByIdxState(via.remoteIdx, Established)
-		f.SendVia(via.relayHI, via.relay, msg, make([]byte, 12), make([]byte, mtu), false)
+		buf := f.bufAlloc.Acquire()
+		f.SendVia(via.relayHI, via.relay, msg, buf)
+		f.bufAlloc.Release(buf)
 		f.l.Info("Handshake message sent", append(logFields, "relay", via.relayHI.vpnAddrs[0])...)
 	}
 }
@@ -1103,7 +1104,9 @@ func (hm *HandshakeManager) handleCheckAndCompleteError(err error, existing, hos
 	switch err {
 	case ErrAlreadySeen:
 		if existing.SetRemoteIfPreferred(f.hostMap, via) {
-			f.SendMessageToVpnAddr(header.Test, header.TestRequest, hostinfo.vpnAddrs[0], []byte(""), make([]byte, 12, 12), make([]byte, mtu))
+			buf := f.bufAlloc.Acquire()
+			f.SendMessageToVpnAddr(header.Test, header.TestRequest, hostinfo.vpnAddrs[0], []byte(""), buf)
+			f.bufAlloc.Release(buf)
 		}
 		// Resend the original response. The peer is committed to that response's
 		// ephemeral keys; a freshly-built one would have different keys and break
@@ -1126,7 +1129,9 @@ func (hm *HandshakeManager) handleCheckAndCompleteError(err error, existing, hos
 			"responderIndex", hostinfo.localIndexId,
 			"handshake", hsFields,
 		)
-		f.SendMessageToVpnAddr(header.Test, header.TestRequest, hostinfo.vpnAddrs[0], []byte(""), make([]byte, 12, 12), make([]byte, mtu))
+		buf := f.bufAlloc.Acquire()
+		f.SendMessageToVpnAddr(header.Test, header.TestRequest, hostinfo.vpnAddrs[0], []byte(""), buf)
+		f.bufAlloc.Release(buf)
 
 	case ErrLocalIndexCollision:
 		f.l.Error("Failed to add HostInfo due to localIndex collision",

handshake_manager_test.go

@@ -80,15 +80,15 @@ func testCountTimerWheelEntries(tw *LockingTimerWheel[netip.Addr]) (c int) {
 type mockEncWriter struct {
 }
 
-func (mw *mockEncWriter) SendMessageToVpnAddr(_ header.MessageType, _ header.MessageSubType, _ netip.Addr, _, _, _ []byte) {
+func (mw *mockEncWriter) SendMessageToVpnAddr(_ header.MessageType, _ header.MessageSubType, _ netip.Addr, _ []byte, _ *WireBuffer) {
 	return
 }
 
-func (mw *mockEncWriter) SendVia(_ *HostInfo, _ *Relay, _, _, _ []byte, _ bool) {
+func (mw *mockEncWriter) SendVia(_ *HostInfo, _ *Relay, _ []byte, _ *WireBuffer) {
 	return
 }
 
-func (mw *mockEncWriter) SendMessageToHostInfo(_ header.MessageType, _ header.MessageSubType, _ *HostInfo, _, _, _ []byte) {
+func (mw *mockEncWriter) SendMessageToHostInfo(_ header.MessageType, _ header.MessageSubType, _ *HostInfo, _ []byte, _ *WireBuffer) {
 	return
 }
 

header/header.go

@@ -174,10 +174,6 @@ func (h *H) SubTypeName() string {
 	return SubTypeName(h.Type, h.Subtype)
 }
 
-func (h *H) IsValidSubType() bool {
-	return IsValidSubType(h.Type, h.Subtype)
-}
-
 // SubTypeName will transform a nebula message sub type into a human string
 func SubTypeName(t MessageType, s MessageSubType) string {
 	if n, ok := subTypeMap[t]; ok {
@@ -189,16 +185,6 @@ func SubTypeName(t MessageType, s MessageSubType) string {
 	return "unknown"
 }
 
-func IsValidSubType(t MessageType, s MessageSubType) bool {
-	if n, ok := subTypeMap[t]; ok {
-		if _, ok := (*n)[s]; ok {
-			return true
-		}
-	}
-
-	return false
-}
-
 // NewHeader turns bytes into a header
 func NewHeader(b []byte) (*H, error) {
 	h := new(H)

hostmap.go

@@ -308,7 +308,7 @@ type cachedPacket struct {
 	packet         []byte
 }
 
-type packetCallback func(t header.MessageType, st header.MessageSubType, h *HostInfo, p, nb, out []byte)
+type packetCallback func(t header.MessageType, st header.MessageSubType, h *HostInfo, p []byte, buf *WireBuffer)
 
 type cachedPacketMetrics struct {
 	sent    metrics.Counter
@@ -691,6 +691,7 @@ func (i *HostInfo) TryPromoteBest(preferredRanges []netip.Prefix, ifce *Interfac
 			}
 		}
 
+		buf := ifce.bufAlloc.Acquire()
 		i.remotes.ForEach(preferredRanges, func(addr netip.AddrPort, preferred bool) {
 			if remote.IsValid() && (!addr.IsValid() || !preferred) {
 				return
@@ -698,8 +699,9 @@ func (i *HostInfo) TryPromoteBest(preferredRanges []netip.Prefix, ifce *Interfac
 
 			// Try to send a test packet to that host, this should
 			// cause it to detect a roaming event and switch remotes
-			ifce.sendTo(header.Test, header.TestRequest, i.ConnectionState, i, addr, []byte(""), make([]byte, 12, 12), make([]byte, mtu))
+			ifce.sendTo(header.Test, header.TestRequest, i.ConnectionState, i, addr, []byte(""), buf)
 		})
+		ifce.bufAlloc.Release(buf)
 	}
 
 	// Re query our lighthouses for new remotes occasionally

inside.go

@@ -2,34 +2,20 @@ package nebula
 
 import (
 	"context"
-	"io"
 	"log/slog"
 	"net/netip"
 
 	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/iputil"
-	"github.com/slackhq/nebula/noiseutil"
-	"github.com/slackhq/nebula/overlay/batch"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 )
 
-func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packet, nb []byte, sendBatch batch.TxBatcher, rejectBuf []byte, q int, localCache firewall.ConntrackCache) {
-	// borrowed: pkt.Bytes is owned by the originating tio.Queue and is
-	// only valid until the next Read on that queue. Every consumer below
-	// (parse, self-forward, handshake cache, sendInsideMessage) reads it
-	// synchronously; do not retain pkt outside this call. If a future
-	// caller needs to keep the packet, use pkt.Clone() to detach it from
-	// the borrow.
-	//
-	// pkt.Bytes is either one IP datagram (GSO zero) or a TSO/USO
-	// superpacket. In both cases the L3+L4 headers at the start describe
-	// the same 5-tuple every segment will share, so a single parse +
-	// firewall check covers the whole superpacket.
-	packet := pkt.Bytes
-	var parsed batch.RxParsed
-	if err := batch.ParsePacket(packet, false, &parsed); err != nil {
+func (f *Interface) consumeInsidePacket(buf *WireBuffer, q int, localCache firewall.ConntrackCache) {
+	packet := buf.IPPacket()
+
+	err := newPacket(packet, false, buf.FwPacket)
+	if err != nil {
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			f.l.Debug("Error while validating outbound packet",
 				"packet", packet,
@@ -39,29 +25,20 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packe
 		return
 	}
 
-	parsed.Key.Hydrate(fwPacket)
-
 	// Ignore local broadcast packets
 	if f.dropLocalBroadcast {
-		if f.myBroadcastAddrsTable.Contains(fwPacket.RemoteAddr) {
+		if f.myBroadcastAddrsTable.Contains(buf.FwPacket.RemoteAddr) {
 			return
 		}
 	}
 
-	if f.myVpnAddrsTable.Contains(fwPacket.RemoteAddr) {
+	if f.myVpnAddrsTable.Contains(buf.FwPacket.RemoteAddr) {
 		// Immediately forward packets from self to self.
 		// This should only happen on Darwin-based and FreeBSD hosts, which
 		// routes packets from the Nebula addr to the Nebula addr through the Nebula
 		// TUN device.
 		if immediatelyForwardToSelf {
-			// Write copies into the kernel queue synchronously, so seg's lifetime ends at return.
-			// A self-forwarded superpacket would be re-handed to the
-			// kernel as one giant blob; segment first so the loopback
-			// path sees one IP datagram per Write.
-			err := tio.SegmentSuperpacket(pkt, func(seg []byte) error {
-				_, werr := f.readers[q].Write(seg)
-				return werr
-			})
+			_, err := f.readers[q].Write(packet)
 			if err != nil {
 				f.l.Error("Failed to forward to tun", "error", err)
 			}
@@ -72,32 +49,20 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packe
 	}
 
 	// Ignore multicast packets
-	if f.dropMulticast && fwPacket.RemoteAddr.IsMulticast() {
+	if f.dropMulticast && buf.FwPacket.RemoteAddr.IsMulticast() {
 		return
 	}
 
-	hostinfo, ready := f.getOrHandshakeConsiderRouting(fwPacket, func(hh *HandshakeHostInfo) {
-		// borrowed: SegmentSuperpacket builds each segment in the kernel-supplied pkt
-		// bytes underneath. cachePacket explicitly copies its argument (handshake_manager.go cachePacket),
-		// so retaining segments past the loop is safe.
-		err := tio.SegmentSuperpacket(pkt, func(seg []byte) error {
-			hh.cachePacket(f.l, header.Message, 0, seg, f.sendMessageNow, f.cachedPacketMetrics)
-			return nil
-		})
-		if err != nil && f.l.Enabled(context.Background(), slog.LevelDebug) {
-			f.l.Debug("Failed to segment superpacket for handshake cache",
-				"error", err,
-				"vpnAddr", fwPacket.RemoteAddr,
-			)
-		}
+	hostinfo, ready := f.getOrHandshakeConsiderRouting(buf.FwPacket, func(hh *HandshakeHostInfo) {
+		hh.cachePacket(f.l, header.Message, 0, packet, f.sendMessageNow, f.cachedPacketMetrics)
 	})
 
 	if hostinfo == nil {
-		f.rejectInside(packet, rejectBuf, q)
+		f.rejectInside(packet, buf.Out, q)
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			f.l.Debug("dropping outbound packet, vpnAddr not in our vpn networks or in unsafe networks",
-				"vpnAddr", fwPacket.RemoteAddr,
-				"fwPacket", fwPacket,
+				"vpnAddr", buf.FwPacket.RemoteAddr,
+				"fwPacket", buf.FwPacket,
 			)
 		}
 		return
@@ -107,163 +72,21 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packe
 		return
 	}
 
-	dropReason := f.firewall.Drop(parsed.Key, fwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
+	dropReason := f.firewall.Drop(*buf.FwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason == nil {
-		f.sendInsideMessage(hostinfo, pkt, nb, sendBatch, rejectBuf, q)
+		f.sendNoMetrics(header.Message, 0, hostinfo.ConnectionState, hostinfo, netip.AddrPort{}, packet, buf, q)
+
 	} else {
-		f.rejectInside(packet, rejectBuf, q)
+		f.rejectInside(packet, buf.Out, q)
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			hostinfo.logger(f.l).Debug("dropping outbound packet",
-				"fwPacket", fwPacket,
+				"fwPacket", buf.FwPacket,
 				"reason", dropReason,
 			)
 		}
 	}
 }
 
-func (f *Interface) sendInsideEncrypt(hostinfo *HostInfo, ci *ConnectionState, seg, scratch, nb []byte) []byte {
-	if noiseutil.EncryptLockNeeded {
-		ci.writeLock.Lock()
-	}
-	c := ci.messageCounter.Add(1)
-
-	out := header.Encode(scratch, header.Version, header.Message, 0, hostinfo.remoteIndexId, c)
-	f.connectionManager.Out(hostinfo)
-
-	out, encErr := ci.eKey.EncryptDanger(out, out, seg, c, nb)
-	if noiseutil.EncryptLockNeeded {
-		ci.writeLock.Unlock()
-	}
-	if encErr != nil {
-		hostinfo.logger(f.l).Error("Failed to encrypt outgoing packet",
-			"error", encErr,
-			"udpAddr", hostinfo.remote,
-			"counter", c,
-		)
-		// Skip this segment; the rest of the superpacket can still
-		// go out — TCP will retransmit anything we drop here.
-		return nil
-	}
-
-	return out
-}
-
-// sendInsideMessage encrypts a firewall-approved inside packet (or every
-// segment of a TSO/USO superpacket) into the caller's batch slot for
-// later sendmmsg flush. Segmentation is fused with encryption here so the
-// kernel-supplied superpacket bytes never get written into a separate
-// scratch arena: SegmentSuperpacket builds each segment's plaintext in
-// segScratch[:segLen] in turn, and we encrypt directly into a fresh
-// SendBatch slot.
-func (f *Interface) sendInsideMessage(hostinfo *HostInfo, pkt tio.Packet, nb []byte, sendBatch batch.TxBatcher, rejectBuf []byte, q int) {
-	ci := hostinfo.ConnectionState
-	if ci.eKey == nil {
-		return
-	}
-
-	ecnEnabled := f.ecnEnabled.Load()
-	if hostinfo.lastRebindCount != f.rebindCount {
-		//NOTE: there is an update hole if a tunnel isn't used and exactly 256 rebinds occur before the tunnel is
-		// finally used again. This tunnel would eventually be torn down and recreated if this action didn't help.
-		f.lightHouse.QueryServer(hostinfo.vpnAddrs[0])
-		hostinfo.lastRebindCount = f.rebindCount
-		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("Lighthouse update triggered for punch due to rebind counter",
-				"vpnAddrs", hostinfo.vpnAddrs,
-			)
-		}
-	}
-
-	if !hostinfo.remote.IsValid() { //the relay path
-		//first, find our relay hostinfo:
-		var relayHostInfo *HostInfo
-		var relay *Relay
-		var err error
-		for _, relayIP := range hostinfo.relayState.CopyRelayIps() {
-			relayHostInfo, relay, err = f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relayIP)
-			if err != nil {
-				hostinfo.relayState.DeleteRelay(relayIP)
-				hostinfo.logger(f.l).Info("sendNoMetrics failed to find HostInfo",
-					"relay", relayIP,
-					"error", err,
-				)
-				continue
-			}
-			break
-		}
-		if relayHostInfo == nil || relay == nil {
-			//failure already logged
-			return
-		}
-
-		err = tio.SegmentSuperpacket(pkt, func(seg []byte) error {
-			//relay header + header + plaintext + AEAD tag (16 bytes for both AES-GCM and ChaCha20-Poly1305) + relay tag
-			scratch := sendBatch.Reserve(header.Len + header.Len + len(seg) + 16 + 16)
-
-			innerPacket := f.sendInsideEncrypt(hostinfo, ci, seg, scratch[header.Len:], nb)
-			if innerPacket == nil {
-				return nil
-			}
-
-			//now we need to do a relay-encrypt:
-			toSend, err := f.prepareSendVia(relayHostInfo, relay, innerPacket, nb, scratch, true)
-			if err != nil {
-				//already logged
-				return nil
-			}
-
-			var ecn byte
-			if ecnEnabled {
-				ecn = innerECN(seg)
-			}
-			sendBatch.Commit(toSend, relayHostInfo.remote, ecn)
-			return nil
-		})
-		if err != nil {
-			hostinfo.logger(f.l).Error("Failed to segment superpacket for relay send", "error", err)
-		}
-		return
-	}
-
-	err := tio.SegmentSuperpacket(pkt, func(seg []byte) error {
-		// header + plaintext + AEAD tag (16 bytes for both AES-GCM and ChaCha20-Poly1305)
-		scratch := sendBatch.Reserve(header.Len + len(seg) + 16)
-
-		out := f.sendInsideEncrypt(hostinfo, ci, seg, scratch, nb)
-		if out == nil {
-			return nil
-		}
-
-		var ecn byte
-		if ecnEnabled {
-			ecn = innerECN(seg)
-		}
-		sendBatch.Commit(out, hostinfo.remote, ecn)
-		return nil
-	})
-	if err != nil {
-		hostinfo.logger(f.l).Error("Failed to segment superpacket for send",
-			"error", err,
-		)
-	}
-}
-
-// innerECN returns the 2-bit IP-level ECN codepoint of an inner IPv4 or IPv6
-// packet, or 0 if pkt is too short or its IP version is unrecognized. Used at
-// encap to copy the inner codepoint onto the outer carrier per RFC 6040.
-func innerECN(pkt []byte) byte {
-	if len(pkt) < 2 {
-		return 0
-	}
-	switch pkt[0] >> 4 {
-	case 4:
-		return pkt[1] & 0x03
-	case 6:
-		return (pkt[1] >> 4) & 0x03
-	}
-	return 0
-}
-
 func (f *Interface) rejectInside(packet []byte, out []byte, q int) {
 	if !f.firewall.InSendReject {
 		return
@@ -280,27 +103,27 @@ func (f *Interface) rejectInside(packet []byte, out []byte, q int) {
 	}
 }
 
-func (f *Interface) rejectOutside(packet []byte, ci *ConnectionState, hostinfo *HostInfo, nb, out []byte, q int) {
+func (f *Interface) rejectOutside(packet []byte, ci *ConnectionState, hostinfo *HostInfo, scratch []byte, buf *WireBuffer, q int) {
 	if !f.firewall.OutSendReject {
 		return
 	}
 
-	out = iputil.CreateRejectPacket(packet, out)
-	if len(out) == 0 {
+	rejectIP := iputil.CreateRejectPacket(packet, scratch)
+	if len(rejectIP) == 0 {
 		return
 	}
 
-	if len(out) > iputil.MaxRejectPacketSize {
+	if len(rejectIP) > iputil.MaxRejectPacketSize {
 		if f.l.Enabled(context.Background(), slog.LevelInfo) {
 			f.l.Info("rejectOutside: packet too big, not sending",
 				"packet", packet,
-				"outPacket", out,
+				"outPacket", rejectIP,
 			)
 		}
 		return
 	}
 
-	f.sendNoMetrics(header.Message, 0, ci, hostinfo, netip.AddrPort{}, out, nb, packet, q)
+	f.sendNoMetrics(header.Message, 0, ci, hostinfo, netip.AddrPort{}, rejectIP, buf, q)
 }
 
 // Handshake will attempt to initiate a tunnel with the provided vpn address. This is a no-op if the tunnel is already established or being established
@@ -393,17 +216,16 @@ func (f *Interface) getOrHandshakeConsiderRouting(fwPacket *firewall.Packet, cac
 
 }
 
-func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p, nb, out []byte) {
-	var parsed batch.RxParsed
-	if err := batch.ParsePacket(p, false, &parsed); err != nil {
+func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p []byte, buf *WireBuffer) {
+	fp := &firewall.Packet{}
+	err := newPacket(p, false, fp)
+	if err != nil {
 		f.l.Warn("error while parsing outgoing packet for firewall check", "error", err)
 		return
 	}
-	fp := &firewall.Packet{}
-	parsed.Key.Hydrate(fp)
 
 	// check if packet is in outbound fw rules
-	dropReason := f.firewall.Drop(parsed.Key, fp, false, hostinfo, f.pki.GetCAPool(), nil)
+	dropReason := f.firewall.Drop(*fp, false, hostinfo, f.pki.GetCAPool(), nil)
 	if dropReason != nil {
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			f.l.Debug("dropping cached packet",
@@ -414,12 +236,12 @@ func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubTyp
 		return
 	}
 
-	f.sendNoMetrics(header.Message, st, hostinfo.ConnectionState, hostinfo, netip.AddrPort{}, p, nb, out, 0)
+	f.sendNoMetrics(header.Message, st, hostinfo.ConnectionState, hostinfo, netip.AddrPort{}, p, buf, 0)
 }
 
 // SendMessageToVpnAddr handles real addr:port lookup and sends to the current best known address for vpnAddr.
 // This function ignores myVpnNetworksTable, and will always attempt to treat the address as a vpnAddr
-func (f *Interface) SendMessageToVpnAddr(t header.MessageType, st header.MessageSubType, vpnAddr netip.Addr, p, nb, out []byte) {
+func (f *Interface) SendMessageToVpnAddr(t header.MessageType, st header.MessageSubType, vpnAddr netip.Addr, p []byte, buf *WireBuffer) {
 	hostInfo, ready := f.handshakeManager.GetOrHandshake(vpnAddr, func(hh *HandshakeHostInfo) {
 		hh.cachePacket(f.l, t, st, p, f.SendMessageToHostInfo, f.cachedPacketMetrics)
 	})
@@ -437,124 +259,73 @@ func (f *Interface) SendMessageToVpnAddr(t header.MessageType, st header.Message
 		return
 	}
 
-	f.SendMessageToHostInfo(t, st, hostInfo, p, nb, out)
+	f.SendMessageToHostInfo(t, st, hostInfo, p, buf)
 }
 
-func (f *Interface) SendMessageToHostInfo(t header.MessageType, st header.MessageSubType, hi *HostInfo, p, nb, out []byte) {
-	f.send(t, st, hi.ConnectionState, hi, p, nb, out)
+func (f *Interface) SendMessageToHostInfo(t header.MessageType, st header.MessageSubType, hi *HostInfo, p []byte, buf *WireBuffer) {
+	f.send(t, st, hi.ConnectionState, hi, p, buf)
 }
 
-func (f *Interface) send(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, p, nb, out []byte) {
+func (f *Interface) send(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, p []byte, buf *WireBuffer) {
 	f.messageMetrics.Tx(t, st, 1)
-	f.sendNoMetrics(t, st, ci, hostinfo, netip.AddrPort{}, p, nb, out, 0)
+	f.sendNoMetrics(t, st, ci, hostinfo, netip.AddrPort{}, p, buf, 0)
 }
 
-func (f *Interface) sendTo(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, remote netip.AddrPort, p, nb, out []byte) {
+func (f *Interface) sendTo(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, remote netip.AddrPort, p []byte, buf *WireBuffer) {
 	f.messageMetrics.Tx(t, st, 1)
-	f.sendNoMetrics(t, st, ci, hostinfo, remote, p, nb, out, 0)
-}
-
-func (f *Interface) prepareSendVia(via *HostInfo,
-	relay *Relay,
-	ad,
-	nb,
-	out []byte,
-	nocopy bool,
-) ([]byte, error) {
-	if noiseutil.EncryptLockNeeded {
-		// NOTE: for goboring AESGCMTLS we need to lock because of the nonce check
-		via.ConnectionState.writeLock.Lock()
-	}
-	c := via.ConnectionState.messageCounter.Add(1)
-
-	out = header.Encode(out, header.Version, header.Message, header.MessageRelay, relay.RemoteIndex, c)
-	f.connectionManager.Out(via)
-
-	// Authenticate the header and payload, but do not encrypt for this message type.
-	// The payload consists of the inner, unencrypted Nebula header, as well as the end-to-end encrypted payload.
-	if len(out)+len(ad)+via.ConnectionState.eKey.Overhead() > cap(out) {
-		if noiseutil.EncryptLockNeeded {
-			via.ConnectionState.writeLock.Unlock()
-		}
-		via.logger(f.l).Error("SendVia out buffer not large enough for relay",
-			"outCap", cap(out),
-			"payloadLen", len(ad),
-			"headerLen", len(out),
-			"cipherOverhead", via.ConnectionState.eKey.Overhead(),
-		)
-		return nil, io.ErrShortBuffer
-	}
-
-	// The header bytes are written to the 'out' slice; Grow the slice to hold the header and associated data payload.
-	offset := len(out)
-	out = out[:offset+len(ad)]
-
-	// In one call path, the associated data _is_ already stored in out. In other call paths, the associated data must
-	// be copied into 'out'.
-	if !nocopy {
-		copy(out[offset:], ad)
-	}
-
-	var err error
-	out, err = via.ConnectionState.eKey.EncryptDanger(out, out, nil, c, nb)
-	if noiseutil.EncryptLockNeeded {
-		via.ConnectionState.writeLock.Unlock()
-	}
-	if err != nil {
-		via.logger(f.l).Info("Failed to EncryptDanger in sendVia", "error", err)
-		return nil, err
-	}
-	f.connectionManager.RelayUsed(relay.LocalIndex)
-	return out, nil
+	f.sendNoMetrics(t, st, ci, hostinfo, remote, p, buf, 0)
 }
 
 // SendVia sends a payload through a Relay tunnel. No authentication or encryption is done
 // to the payload for the ultimate target host, making this a useful method for sending
 // handshake messages to peers through relay tunnels.
-// via is the HostInfo through which the message is relayed.
-// ad is the plaintext data to authenticate, but not encrypt
-// nb is a buffer used to store the nonce value, re-used for performance reasons.
-// out is a buffer used to store the result of the Encrypt operation
-// q indicates which writer to use to send the packet.
-func (f *Interface) SendVia(via *HostInfo,
-	relay *Relay,
-	ad,
-	nb,
-	out []byte,
-	nocopy bool,
-) {
-	toSend, err := f.prepareSendVia(via, relay, ad, nb, out, nocopy)
-	err = f.writers[0].WriteTo(toSend, via.remote)
-	if err != nil {
-		via.logger(f.l).Info("Failed to WriteTo in sendVia", "error", err)
+//
+// via is the HostInfo through which the message is relayed. ad is staged into
+// the inner-payload slot of buf and then AAD-only sealed under via's key by
+// SealRelayInPlace. The sendNoMetrics relay-forward path skips this entry
+// point and calls sendViaInPlace directly because its inner ciphertext is
+// already in place from the encrypt step.
+func (f *Interface) SendVia(via *HostInfo, relay *Relay, ad []byte, buf *WireBuffer) {
+	if header.Len+len(ad)+via.ConnectionState.eKey.Overhead() > cap(buf.Out) {
+		via.logger(f.l).Error("SendVia out buffer not large enough for relay",
+			"outCap", cap(buf.Out),
+			"payloadLen", len(ad),
+			"headerLen", header.Len,
+			"cipherOverhead", via.ConnectionState.eKey.Overhead(),
+		)
+		return
 	}
+	buf.StageRelayInner(ad)
+	f.sendViaInPlace(via, relay, len(ad), buf)
 }
 
-func (f *Interface) sendNoMetrics(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, remote netip.AddrPort, p, nb, out []byte, q int) {
+// sendViaInPlace stamps the outer relay header, AAD-seals over the [outer
+// header | inner-already-staged] region, and writes the result to via.remote.
+// Called from SendVia (after staging ad) and from sendNoMetrics' relay-forward
+// path (where the inner ciphertext is already in place from SealForRelay).
+func (f *Interface) sendViaInPlace(via *HostInfo, relay *Relay, innerLen int, buf *WireBuffer) {
+	f.connectionManager.Out(via)
+	out, err := buf.SealRelayInPlace(via.ConnectionState, relay.RemoteIndex, innerLen)
+	if err != nil {
+		via.logger(f.l).Info("Failed to EncryptDanger in sendVia", "error", err)
+		return
+	}
+	if err := f.writers[0].WriteTo(out, via.remote); err != nil {
+		via.logger(f.l).Info("Failed to WriteTo in sendVia", "error", err)
+	}
+	f.connectionManager.RelayUsed(relay.LocalIndex)
+}
+
+// sendNoMetrics encrypts and writes one outbound nebula packet (data, control,
+// lighthouse, etc) using buf as the per-call wire scratch. When the hostinfo
+// has no direct remote we encrypt into the relay-reserved slot via
+// SealForRelay so sendViaInPlace can wrap it without an extra copy.
+func (f *Interface) sendNoMetrics(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, remote netip.AddrPort, p []byte, buf *WireBuffer, q int) {
 	if ci.eKey == nil {
 		return
 	}
 	useRelay := !remote.IsValid() && !hostinfo.remote.IsValid()
-	fullOut := out
 
-	if useRelay {
-		if len(out) < header.Len {
-			// out always has a capacity of mtu, but not always a length greater than the header.Len.
-			// Grow it to make sure the next operation works.
-			out = out[:header.Len]
-		}
-		// Save a header's worth of data at the front of the 'out' buffer.
-		out = out[header.Len:]
-	}
-
-	if noiseutil.EncryptLockNeeded {
-		// NOTE: for goboring AESGCMTLS we need to lock because of the nonce check
-		ci.writeLock.Lock()
-	}
-	c := ci.messageCounter.Add(1)
-
-	//l.WithField("trace", string(debug.Stack())).Error("out Header ", &Header{Version, t, st, 0, hostinfo.remoteIndexId, c}, p)
-	out = header.Encode(out, header.Version, t, st, hostinfo.remoteIndexId, c)
 	f.connectionManager.Out(hostinfo)
 
 	// Query our LH if we haven't since the last time we've been rebound, this will cause the remote to punch against
@@ -571,50 +342,42 @@ func (f *Interface) sendNoMetrics(t header.MessageType, st header.MessageSubType
 		}
 	}
 
+	var out []byte
 	var err error
-	out, err = ci.eKey.EncryptDanger(out, out, p, c, nb)
-	if noiseutil.EncryptLockNeeded {
-		ci.writeLock.Unlock()
+	if useRelay {
+		out, err = buf.SealForRelay(ci, t, st, hostinfo.remoteIndexId, p)
+	} else {
+		out, err = buf.Seal(ci, t, st, hostinfo.remoteIndexId, p)
 	}
 	if err != nil {
 		hostinfo.logger(f.l).Error("Failed to encrypt outgoing packet",
 			"error", err,
 			"udpAddr", remote,
-			"counter", c,
-			"attemptedCounter", c,
 		)
 		return
 	}
 
-	if remote.IsValid() {
-		err = f.writers[q].WriteTo(out, remote)
-		if err != nil {
-			hostinfo.logger(f.l).Error("Failed to write outgoing packet",
-				"error", err,
-				"udpAddr", remote,
-			)
+	switch {
+	case remote.IsValid():
+		if err := f.writers[q].WriteTo(out, remote); err != nil {
+			hostinfo.logger(f.l).Error("Failed to write outgoing packet", "error", err, "udpAddr", remote)
 		}
-	} else if hostinfo.remote.IsValid() {
-		err = f.writers[q].WriteTo(out, hostinfo.remote)
-		if err != nil {
-			hostinfo.logger(f.l).Error("Failed to write outgoing packet",
-				"error", err,
-				"udpAddr", remote,
-			)
+	case hostinfo.remote.IsValid():
+		if err := f.writers[q].WriteTo(out, hostinfo.remote); err != nil {
+			hostinfo.logger(f.l).Error("Failed to write outgoing packet", "error", err, "udpAddr", hostinfo.remote)
 		}
-	} else {
-		// Try to send via a relay
+	default:
+		// SealForRelay placed the inner ciphertext at buf.Out[header.Len:],
+		// so sendViaInPlace can wrap it with the outer relay header without
+		// an extra copy.
 		for _, relayIP := range hostinfo.relayState.CopyRelayIps() {
 			relayHostInfo, relay, err := f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relayIP)
 			if err != nil {
 				hostinfo.relayState.DeleteRelay(relayIP)
-				hostinfo.logger(f.l).Info("sendNoMetrics failed to find HostInfo",
-					"relay", relayIP,
-					"error", err,
-				)
+				hostinfo.logger(f.l).Info("sendNoMetrics failed to find HostInfo", "relay", relayIP, "error", err)
 				continue
 			}
-			f.SendVia(relayHostInfo, relay, out, nb, fullOut[:header.Len+len(out)], true)
+			f.sendViaInPlace(relayHostInfo, relay, len(out), buf)
 			break
 		}
 	}

interface.go

@@ -4,23 +4,20 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/netip"
-	"runtime"
 	"sync"
 	"sync/atomic"
 	"time"
 
 	"github.com/gaissmai/bart"
 	"github.com/rcrowley/go-metrics"
-	"github.com/slackhq/nebula/util"
 
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/overlay"
-	"github.com/slackhq/nebula/overlay/batch"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/udp"
 )
 
@@ -50,14 +47,7 @@ type InterfaceConfig struct {
 	reQueryWait     time.Duration
 
 	ConntrackCacheTimeout time.Duration
-
-	// CpuAffinity, when non-empty, names the CPUs each TUN reader goroutine
-	// should pin to. Queue i pins to CpuAffinity[i % len(CpuAffinity)] —
-	// shorter lists than `routines` cycle. Empty list keeps the default
-	// pin-to-(i % NumCPU) behavior.
-	CpuAffinity []int
-
-	l *slog.Logger
+	l                     *slog.Logger
 }
 
 type Interface struct {
@@ -81,16 +71,7 @@ type Interface struct {
 	routines              int
 	disconnectInvalid     atomic.Bool
 	closed                atomic.Bool
-	// cpuAffinity, when non-empty, names the CPUs each TUN reader goroutine
-	// should pin to. Queue i pins to cpuAffinity[i % len(cpuAffinity)].
-	// Empty falls back to the default pin-to-(i % NumCPU) behavior.
-	cpuAffinity []int
-	// ecnEnabled gates RFC 6040 underlay ECN propagation. When true,
-	// inside.go copies the inner ECN onto the outer carrier on encap and
-	// decryptToTun folds outer CE into the inner header on decap. Toggle
-	// via tunnels.ecn (default true).
-	ecnEnabled   atomic.Bool
-	relayManager *relayManager
+	relayManager          *relayManager
 
 	tryPromoteEvery atomic.Uint32
 	reQueryEvery    atomic.Uint32
@@ -107,12 +88,8 @@ type Interface struct {
 
 	ctx     context.Context
 	writers []udp.Conn
-	readers []tio.Queue
-	// batchers is one per tun queue, wrapping readers[i].
-	// decryptToTun sends plaintext into the batch.RxBatcher;
-	// listenOut calls its Flush at the end of each UDP recvmmsg batch.
-	batchers []batch.RxBatcher
-	wg       sync.WaitGroup
+	readers []io.ReadWriteCloser
+	wg      sync.WaitGroup
 
 	// fatalErr holds the first unexpected reader error that caused shutdown.
 	// nil means "no fatal error" (yet)
@@ -124,19 +101,19 @@ type Interface struct {
 	messageMetrics      *MessageMetrics
 	cachedPacketMetrics *cachedPacketMetrics
 
+	// bufAlloc hands out reusable WireBuffers sized for this interface's
+	// inside Device. All buf consumers (hot-path data-plane goroutines,
+	// long-lived workers, and cold callers) acquire from here so sizing
+	// is centralized and consistent. Long-lived owners just don't release.
+	bufAlloc WireBufferAllocator
+
 	l *slog.Logger
 }
 
 type EncWriter interface {
-	SendVia(via *HostInfo,
-		relay *Relay,
-		ad,
-		nb,
-		out []byte,
-		nocopy bool,
-	)
-	SendMessageToVpnAddr(t header.MessageType, st header.MessageSubType, vpnAddr netip.Addr, p, nb, out []byte)
-	SendMessageToHostInfo(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p, nb, out []byte)
+	SendVia(via *HostInfo, relay *Relay, ad []byte, buf *WireBuffer)
+	SendMessageToVpnAddr(t header.MessageType, st header.MessageSubType, vpnAddr netip.Addr, p []byte, buf *WireBuffer)
+	SendMessageToHostInfo(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p []byte, buf *WireBuffer)
 	Handshake(vpnAddr netip.Addr)
 	GetHostInfo(vpnAddr netip.Addr) *HostInfo
 	GetCertState() *CertState
@@ -210,8 +187,7 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		routines:              c.routines,
 		version:               c.version,
 		writers:               make([]udp.Conn, c.routines),
-		readers:               make([]tio.Queue, c.routines),
-		batchers:              make([]batch.RxBatcher, c.routines),
+		readers:               make([]io.ReadWriteCloser, c.routines),
 		myVpnNetworks:         cs.myVpnNetworks,
 		myVpnNetworksTable:    cs.myVpnNetworksTable,
 		myVpnAddrs:            cs.myVpnAddrs,
@@ -220,7 +196,6 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		relayManager:          c.relayManager,
 		connectionManager:     c.connectionManager,
 		conntrackCacheTimeout: c.ConntrackCacheTimeout,
-		cpuAffinity:           c.CpuAffinity,
 
 		metricHandshakes: metrics.GetOrRegisterHistogram("handshakes", nil, metrics.NewExpDecaySample(1028, 0.015)),
 		messageMetrics:   c.MessageMetrics,
@@ -229,6 +204,8 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 			dropped: metrics.GetOrRegisterCounter("hostinfo.cached_packets.dropped", nil),
 		},
 
+		bufAlloc: NewWireBufferPool(mtu, c.Inside.TunPrefixLen()),
+
 		l: c.l,
 	}
 
@@ -270,25 +247,15 @@ func (f *Interface) activate() error {
 	metrics.GetOrRegisterGauge("routines", nil).Update(int64(f.routines))
 
 	// Prepare n tun queues
+	var reader io.ReadWriteCloser = f.inside
 	for i := 0; i < f.routines; i++ {
 		if i > 0 {
-			if err = f.inside.NewMultiQueueReader(); err != nil {
+			reader, err = f.inside.NewMultiQueueReader()
+			if err != nil {
 				return err
 			}
 		}
-	}
-	f.readers = f.inside.Readers()
-	for i := range f.readers {
-		caps := tio.QueueCapabilities(f.readers[i])
-		if caps.TSO || caps.USO {
-			// Multi-lane: TCP gets coalesced when TSO is on, UDP when USO
-			// is on, everything else (and either lane disabled) falls
-			// through to passthrough so non-IP / non-TCP-UDP traffic still
-			// reaches the TUN.
-			f.batchers[i] = batch.NewMultiCoalescer(f.readers[i], caps.TSO, caps.USO)
-		} else {
-			f.batchers[i] = batch.NewPassthrough(f.readers[i])
-		}
+		f.readers[i] = reader
 	}
 
 	f.wg.Add(1) // for us to wait on Close() to return
@@ -346,23 +313,12 @@ func (f *Interface) listenOut(i int) {
 
 	ctCache := firewall.NewConntrackCacheTicker(f.ctx, f.l, f.conntrackCacheTimeout)
 	lhh := f.lightHouse.NewRequestHandler()
-	h := &header.H{}
-	fwPacket := &firewall.Packet{}
-	parsedRx := &batch.RxParsed{}
-	nb := make([]byte, 12, 12)
+	// Long-lived per-receive-goroutine buf; never released back to the pool.
+	buf := f.bufAlloc.Acquire()
 
-	listener := func(fromUdpAddr netip.AddrPort, payload []byte, meta udp.RxMeta) {
-		plaintext := f.batchers[i].Reserve(len(payload))
-		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, plaintext[:0], payload, h, fwPacket, parsedRx, lhh, nb, i, ctCache.Get(), meta)
-	}
-
-	flusher := func() {
-		if err := f.batchers[i].Flush(); err != nil {
-			f.l.Error("Failed to flush tun coalescer", "error", err)
-		}
-	}
-
-	err := li.ListenOut(listener, flusher)
+	err := li.ListenOut(func(fromUdpAddr netip.AddrPort, payload []byte) {
+		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, buf, payload, lhh, i, ctCache.Get())
+	})
 
 	if err != nil && !f.closed.Load() {
 		f.l.Error("Error while reading inbound packet, closing", "error", err)
@@ -372,35 +328,13 @@ func (f *Interface) listenOut(i int) {
 	f.l.Debug("underlay reader is done", "reader", i)
 }
 
-func (f *Interface) listenIn(reader tio.Queue, i int) {
-	// Pin this goroutine to one CPU. LockOSThread alone keeps the goroutine
-	// on a single OS thread but the kernel can still migrate that thread
-	// across CPUs — XPS reads smp_processor_id() at sendmmsg time and picks
-	// the TX ring from the current CPU's xps_cpus map, so an unpinned
-	// thread bouncing between CPUs spreads one nebula flow's packets across
-	// multiple TX rings, which the rings then drain at independent rates
-	// and the wire delivers reordered.
-	//
-	// Pinning keeps every sendmmsg from this goroutine going through the
-	// same TX ring, so the wire sees per-flow order. Cost: less scheduler
-	// flexibility — if i % NumCPU collides between two TUN reader
-	// goroutines they share a CPU.
-	cpu := i % runtime.NumCPU()
-	if n := len(f.cpuAffinity); n > 0 {
-		cpu = f.cpuAffinity[i%n]
-	}
-	if err := util.PinThreadToCPU(cpu); err != nil {
-		f.l.Warn("failed to pin tun reader to CPU", "queue", i, "cpu", cpu, "err", err)
-	}
-	rejectBuf := make([]byte, mtu)
-	sb := batch.NewSendBatch(f.writers[i], batch.SendBatchCap, udp.MTU+32)
-	fwPacket := &firewall.Packet{}
-	nb := make([]byte, 12, 12)
-
+func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
+	// Long-lived per-tun-reader buf; never released back to the pool.
+	buf := f.bufAlloc.Acquire()
 	conntrackCache := firewall.NewConntrackCacheTicker(f.ctx, f.l, f.conntrackCacheTimeout)
 
 	for {
-		pkts, err := reader.Read()
+		_, err := buf.ReadIPFromTUN(reader)
 		if err != nil {
 			if !f.closed.Load() {
 				f.l.Error("Error while reading outbound packet, closing", "error", err, "reader", i)
@@ -409,12 +343,7 @@ func (f *Interface) listenIn(reader tio.Queue, i int) {
 			break
 		}
 
-		for _, pkt := range pkts {
-			f.consumeInsidePacket(pkt, fwPacket, nb, sb, rejectBuf, i, conntrackCache.Get())
-		}
-		if err := sb.Flush(); err != nil {
-			f.l.Error("Failed to write outgoing batch", "error", err, "writer", i)
-		}
+		f.consumeInsidePacket(buf, i, conntrackCache.Get())
 	}
 
 	f.l.Debug("overlay reader is done", "reader", i)
@@ -426,7 +355,6 @@ func (f *Interface) RegisterConfigChangeCallbacks(c *config.C) {
 	c.RegisterReloadCallback(f.reloadAcceptRecvError)
 	c.RegisterReloadCallback(f.reloadDisconnectInvalid)
 	c.RegisterReloadCallback(f.reloadMisc)
-	c.RegisterReloadCallback(f.reloadEcn)
 
 	for _, udpConn := range f.writers {
 		c.RegisterReloadCallback(udpConn.ReloadConfig)
@@ -550,20 +478,6 @@ func (f *Interface) reloadMisc(c *config.C) {
 	}
 }
 
-// reloadEcn syncs Interface.ecnEnabled with the tunnels.ecn config knob.
-// Default is enabled (RFC 6040 normal mode); set false on the rare path
-// where an underlay middlebox rewrites or drops ECN bits unpredictably.
-func (f *Interface) reloadEcn(c *config.C) {
-	initial := c.InitialLoad()
-	if initial || c.HasChanged("tunnels.ecn") {
-		v := c.GetBool("tunnels.ecn", true)
-		f.ecnEnabled.Store(v)
-		if !initial {
-			f.l.Info("tunnels.ecn changed", "enabled", v)
-		}
-	}
-}
-
 func (f *Interface) emitStats(ctx context.Context, i time.Duration) {
 	ticker := time.NewTicker(i)
 	defer ticker.Stop()

lighthouse.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/gaissmai/bart"
+	"github.com/rcrowley/go-metrics"
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/header"
@@ -34,6 +35,7 @@ type LightHouse struct {
 
 	myVpnNetworks      []netip.Prefix
 	myVpnNetworksTable *bart.Lite
+	punchConn          udp.Conn
 	punchy             *Punchy
 
 	// Local cache of answers from light houses
@@ -61,7 +63,11 @@ type LightHouse struct {
 	interval     atomic.Int64
 	updateCancel context.CancelFunc
 	ifce         EncWriter
-	nebulaPort   uint32 // 32 bits because protobuf does not have a uint16
+	// bufAlloc lets the lighthouse query/update workers, request handlers
+	// and punchback goroutines acquire correctly sized WireBuffers from
+	// the same pool as the data plane. Set by main.go alongside ifce.
+	bufAlloc   WireBufferAllocator
+	nebulaPort uint32 // 32 bits because protobuf does not have a uint16
 
 	advertiseAddrs atomic.Pointer[[]netip.AddrPort]
 
@@ -73,8 +79,9 @@ type LightHouse struct {
 
 	calculatedRemotes atomic.Pointer[bart.Table[[]*calculatedRemote]] // Maps VpnAddr to []*calculatedRemote
 
-	metrics *MessageMetrics
-	l       *slog.Logger
+	metrics           *MessageMetrics
+	metricHolepunchTx metrics.Counter
+	l                 *slog.Logger
 }
 
 // NewLightHouseFromConfig will build a Lighthouse struct from the values provided in the config object
@@ -102,10 +109,15 @@ func NewLightHouseFromConfig(ctx context.Context, l *slog.Logger, c *config.C, c
 		myVpnNetworksTable: cs.myVpnNetworksTable,
 		addrMap:            make(map[netip.Addr]*RemoteList),
 		nebulaPort:         nebulaPort,
+		punchConn:          pc,
 		punchy:             p,
 		updateTrigger:      make(chan struct{}, 1),
 		queryChan:          make(chan netip.Addr, c.GetUint32("handshakes.query_buffer", 64)),
-		l:                  l,
+		// Default to a no-prefix pool so the query/update workers and
+		// request handlers have a working WireBufferAllocator before
+		// main.go wires up the real one from the Interface.
+		bufAlloc: NewWireBufferPool(mtu, 0),
+		l:        l,
 	}
 	lighthouses := make([]netip.Addr, 0)
 	h.lighthouses.Store(&lighthouses)
@@ -114,6 +126,9 @@ func NewLightHouseFromConfig(ctx context.Context, l *slog.Logger, c *config.C, c
 
 	if c.GetBool("stats.lighthouse_metrics", false) {
 		h.metrics = newLighthouseMetrics()
+		h.metricHolepunchTx = metrics.GetOrRegisterCounter("messages.tx.holepunch", nil)
+	} else {
+		h.metricHolepunchTx = metrics.NilCounter{}
 	}
 
 	err := h.reload(c, true)
@@ -751,21 +766,22 @@ func (lh *LightHouse) startQueryWorker() {
 	}
 
 	go func() {
-		nb := make([]byte, 12, 12)
-		out := make([]byte, mtu)
+		// Long-lived per-worker WireBuffer; reused for every lighthouse query
+		// this worker issues for the life of the goroutine.
+		buf := lh.bufAlloc.Acquire()
 
 		for {
 			select {
 			case <-lh.ctx.Done():
 				return
 			case addr := <-lh.queryChan:
-				lh.innerQueryServer(addr, nb, out)
+				lh.innerQueryServer(addr, buf)
 			}
 		}
 	}()
 }
 
-func (lh *LightHouse) innerQueryServer(addr netip.Addr, nb, out []byte) {
+func (lh *LightHouse) innerQueryServer(addr netip.Addr, buf *WireBuffer) {
 	if lh.IsLighthouseAddr(addr) {
 		return
 	}
@@ -814,7 +830,7 @@ func (lh *LightHouse) innerQueryServer(addr netip.Addr, nb, out []byte) {
 				}
 			}
 
-			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v1Query, nb, out)
+			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v1Query, buf)
 			queried++
 
 		} else if v == cert.Version2 {
@@ -833,7 +849,7 @@ func (lh *LightHouse) innerQueryServer(addr netip.Addr, nb, out []byte) {
 				}
 			}
 
-			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v2Query, nb, out)
+			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v2Query, buf)
 			queried++
 
 		} else {
@@ -862,8 +878,12 @@ func (lh *LightHouse) StartUpdateWorker() {
 	go func() {
 		defer clockSource.Stop()
 
+		// Long-lived per-worker WireBuffer; reused across every periodic
+		// update for the life of this goroutine.
+		buf := lh.bufAlloc.Acquire()
+
 		for {
-			lh.SendUpdate()
+			lh.sendUpdate(buf)
 
 			select {
 			case <-updateCtx.Done():
@@ -877,6 +897,15 @@ func (lh *LightHouse) StartUpdateWorker() {
 	}()
 }
 
+// SendUpdate is the public entry point that triggers a one-shot lighthouse
+// update outside the worker loop (e.g. tests or reload paths). It allocates
+// its own WireBuffer since callers don't already own one.
+func (lh *LightHouse) SendUpdate() {
+	buf := lh.bufAlloc.Acquire()
+	defer lh.bufAlloc.Release(buf)
+	lh.sendUpdate(buf)
+}
+
 // TriggerUpdate requests an immediate lighthouse update. This is a non-blocking
 // operation intended to be called after a handshake completes with a lighthouse,
 // so the lighthouse has our current addresses without waiting for the next
@@ -888,7 +917,7 @@ func (lh *LightHouse) TriggerUpdate() {
 	}
 }
 
-func (lh *LightHouse) SendUpdate() {
+func (lh *LightHouse) sendUpdate(buf *WireBuffer) {
 	var v4 []*V4AddrPort
 	var v6 []*V6AddrPort
 
@@ -914,9 +943,6 @@ func (lh *LightHouse) SendUpdate() {
 		}
 	}
 
-	nb := make([]byte, 12, 12)
-	out := make([]byte, mtu)
-
 	var v1Update, v2Update []byte
 	var err error
 	updated := 0
@@ -967,7 +993,7 @@ func (lh *LightHouse) SendUpdate() {
 				}
 			}
 
-			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v1Update, nb, out)
+			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v1Update, buf)
 			updated++
 
 		} else if v == cert.Version2 {
@@ -996,7 +1022,7 @@ func (lh *LightHouse) SendUpdate() {
 				}
 			}
 
-			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v2Update, nb, out)
+			lh.ifce.SendMessageToVpnAddr(header.LightHouse, 0, lhVpnAddr, v2Update, buf)
 			updated++
 
 		} else {
@@ -1012,9 +1038,11 @@ func (lh *LightHouse) SendUpdate() {
 }
 
 type LightHouseHandler struct {
-	lh   *LightHouse
-	nb   []byte
-	out  []byte
+	lh *LightHouse
+	// buf is the long-lived per-handler wire scratch. NewRequestHandler is
+	// called once per data-plane receive goroutine, so buf is owned by that
+	// goroutine and reused for every lighthouse send the handler issues.
+	buf  *WireBuffer
 	pb   []byte
 	meta *NebulaMeta
 	l    *slog.Logger
@@ -1023,8 +1051,7 @@ type LightHouseHandler struct {
 func (lh *LightHouse) NewRequestHandler() *LightHouseHandler {
 	lhh := &LightHouseHandler{
 		lh:  lh,
-		nb:  make([]byte, 12, 12),
-		out: make([]byte, mtu),
+		buf: lh.bufAlloc.Acquire(),
 		l:   lh.l,
 		pb:  make([]byte, mtu),
 
@@ -1161,7 +1188,7 @@ func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, fromVpnAddrs []neti
 	}
 
 	lhh.lh.metricTx(NebulaMeta_HostQueryReply, 1)
-	w.SendMessageToVpnAddr(header.LightHouse, 0, fromVpnAddrs[0], lhh.pb[:ln], lhh.nb, lhh.out[:0])
+	w.SendMessageToVpnAddr(header.LightHouse, 0, fromVpnAddrs[0], lhh.pb[:ln], lhh.buf)
 
 	lhh.sendHostPunchNotification(n, fromVpnAddrs, queryVpnAddr, w)
 }
@@ -1221,7 +1248,7 @@ func (lhh *LightHouseHandler) sendHostPunchNotification(n *NebulaMeta, fromVpnAd
 	}
 
 	lhh.lh.metricTx(NebulaMeta_HostPunchNotification, 1)
-	w.SendMessageToVpnAddr(header.LightHouse, 0, punchNotifDest, lhh.pb[:ln], lhh.nb, lhh.out[:0])
+	w.SendMessageToVpnAddr(header.LightHouse, 0, punchNotifDest, lhh.pb[:ln], lhh.buf)
 }
 
 func (lhh *LightHouseHandler) coalesceAnswers(v cert.Version, c *cache, n *NebulaMeta) {
@@ -1378,7 +1405,7 @@ func (lhh *LightHouseHandler) handleHostUpdateNotification(n *NebulaMeta, fromVp
 	}
 
 	lhh.lh.metricTx(NebulaMeta_HostUpdateNotificationAck, 1)
-	w.SendMessageToVpnAddr(header.LightHouse, 0, fromVpnAddrs[0], lhh.pb[:ln], lhh.nb, lhh.out[:0])
+	w.SendMessageToVpnAddr(header.LightHouse, 0, fromVpnAddrs[0], lhh.pb[:ln], lhh.buf)
 }
 
 func (lhh *LightHouseHandler) handleHostPunchNotification(n *NebulaMeta, fromVpnAddrs []netip.Addr, w EncWriter) {
@@ -1399,25 +1426,61 @@ func (lhh *LightHouseHandler) handleHostPunchNotification(n *NebulaMeta, fromVpn
 		return
 	}
 
+	empty := []byte{0}
+	punch := func(vpnPeer netip.AddrPort, logVpnAddr netip.Addr) {
+		if !vpnPeer.IsValid() {
+			return
+		}
+
+		go func() {
+			time.Sleep(lhh.lh.punchy.GetDelay())
+			lhh.lh.metricHolepunchTx.Inc(1)
+			lhh.lh.punchConn.WriteTo(empty, vpnPeer)
+		}()
+
+		if lhh.l.Enabled(context.Background(), slog.LevelDebug) {
+			lhh.l.Debug("Punching",
+				"vpnPeer", vpnPeer,
+				"logVpnAddr", logVpnAddr,
+			)
+		}
+	}
+
 	remoteAllowList := lhh.lh.GetRemoteAllowList()
 	for _, a := range n.Details.V4AddrPorts {
 		b := protoV4AddrPortToNetAddrPort(a)
 		if remoteAllowList.Allow(detailsVpnAddr, b.Addr()) {
-			lhh.lh.punchy.Schedule(b, detailsVpnAddr)
+			punch(b, detailsVpnAddr)
 		}
 	}
 
 	for _, a := range n.Details.V6AddrPorts {
 		b := protoV6AddrPortToNetAddrPort(a)
 		if remoteAllowList.Allow(detailsVpnAddr, b.Addr()) {
-			lhh.lh.punchy.Schedule(b, detailsVpnAddr)
+			punch(b, detailsVpnAddr)
 		}
 	}
 
 	// This sends a nebula test packet to the host trying to contact us. In the case
 	// of a double nat or other difficult scenario, this may help establish
-	// a tunnel. ScheduleRespond is a no-op when punchy.respond is disabled.
-	lhh.lh.punchy.ScheduleRespond(detailsVpnAddr)
+	// a tunnel.
+	if lhh.lh.punchy.GetRespond() {
+		go func() {
+			time.Sleep(lhh.lh.punchy.GetRespondDelay())
+			if lhh.l.Enabled(context.Background(), slog.LevelDebug) {
+				lhh.l.Debug("Sending a nebula test packet",
+					"vpnAddr", detailsVpnAddr,
+				)
+			}
+			// We acquire and release a fresh buf within this goroutine so it
+			// returns to the pool once the punchback send completes. We
+			// should move this into a timerwheel or a single goroutine
+			// managed by a channel.
+			pbuf := lhh.lh.bufAlloc.Acquire()
+			defer lhh.lh.bufAlloc.Release(pbuf)
+			w.SendMessageToVpnAddr(header.Test, header.TestRequest, detailsVpnAddr, []byte(""), pbuf)
+		}()
+	}
 }
 
 func protoAddrToNetAddr(addr *Addr) netip.Addr {

lighthouse_test.go

@@ -372,12 +372,12 @@ type testEncWriter struct {
 	protocolVersion cert.Version
 }
 
-func (tw *testEncWriter) SendVia(via *HostInfo, relay *Relay, ad, nb, out []byte, nocopy bool) {
+func (tw *testEncWriter) SendVia(via *HostInfo, relay *Relay, ad []byte, buf *WireBuffer) {
 }
 func (tw *testEncWriter) Handshake(vpnIp netip.Addr) {
 }
 
-func (tw *testEncWriter) SendMessageToHostInfo(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p, _, _ []byte) {
+func (tw *testEncWriter) SendMessageToHostInfo(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p []byte, _ *WireBuffer) {
 	msg := &NebulaMeta{}
 	err := msg.Unmarshal(p)
 	if tw.metaFilter == nil || msg.Type == *tw.metaFilter {
@@ -394,7 +394,7 @@ func (tw *testEncWriter) SendMessageToHostInfo(t header.MessageType, st header.M
 	}
 }
 
-func (tw *testEncWriter) SendMessageToVpnAddr(t header.MessageType, st header.MessageSubType, vpnIp netip.Addr, p, _, _ []byte) {
+func (tw *testEncWriter) SendMessageToVpnAddr(t header.MessageType, st header.MessageSubType, vpnIp netip.Addr, p []byte, _ *WireBuffer) {
 	msg := &NebulaMeta{}
 	err := msg.Unmarshal(p)
 	if tw.metaFilter == nil || msg.Type == *tw.metaFilter {

main.go

@@ -5,10 +5,7 @@ import (
 	"fmt"
 	"log/slog"
 	"net"
-	"net/http"
-	_ "net/http/pprof"
 	"net/netip"
-	"runtime"
 	"runtime/debug"
 	"strings"
 	"time"
@@ -36,9 +33,6 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 		buildVersion = moduleVersion()
 	}
 
-	//todo no merge
-	go http.ListenAndServe(":6060", nil)
-
 	// Print the config if in test, the exit comes later
 	if configTest {
 		b, err := yaml.Marshal(c.Settings)
@@ -61,7 +55,7 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 	}
 	l.Info("Firewall started", "firewallHashes", fw.GetRuleHashes())
 
-	ssh, err := sshd.NewSSHServer(ctx, l.With("subsystem", "sshd"))
+	ssh, err := sshd.NewSSHServer(l.With("subsystem", "sshd"))
 	if err != nil {
 		return nil, util.ContextualizeIfNeeded("Error while creating SSH server", err)
 	}
@@ -176,7 +170,7 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 	}
 
 	hostMap := NewHostMapFromConfig(l, c)
-	punchy := NewPunchyFromConfig(l, c, udpConns[0])
+	punchy := NewPunchyFromConfig(l, c)
 	connManager := newConnectionManagerFromConfig(l, c, hostMap, punchy)
 	lightHouse, err := NewLightHouseFromConfig(ctx, l, c, pki.getCertState(), udpConns[0], punchy)
 	if err != nil {
@@ -226,7 +220,6 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 		relayManager:          NewRelayManager(ctx, l, hostMap, c),
 		punchy:                punchy,
 		ConntrackCacheTimeout: conntrackCacheTimeout,
-		CpuAffinity:           parseCpuAffinity(c, l, routines),
 		l:                     l,
 	}
 
@@ -239,17 +232,15 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 
 		ifce.writers = udpConns
 		lightHouse.ifce = ifce
+		lightHouse.bufAlloc = ifce.bufAlloc
 
 		ifce.RegisterConfigChangeCallbacks(c)
 		ifce.reloadDisconnectInvalid(c)
 		ifce.reloadSendRecvError(c)
 		ifce.reloadAcceptRecvError(c)
-		ifce.reloadEcn(c)
 
 		handshakeManager.f = ifce
 		go handshakeManager.Run(ctx)
-
-		punchy.Start(ctx, ifce, hostMap, lightHouse)
 	}
 
 	stats, err := newStatsServerFromConfig(ctx, l, c, buildVersion, configTest)
@@ -279,53 +270,6 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 	}, nil
 }
 
-// parseCpuAffinity reads `tun.cpu_affinity` from the config — a list of
-// integer CPU IDs, one per TUN reader goroutine. Empty / unset returns nil
-// (listenIn falls back to its default `i % NumCPU` pinning). Length
-// mismatch with `routines` is a warning, not an error: shorter lists are
-// modulo-cycled across queues, longer lists' tail is ignored. Invalid
-// entries (non-integer, out of range) are also a warning and disable the
-// override entirely so we don't silently pin to the wrong CPU.
-func parseCpuAffinity(c *config.C, l *slog.Logger, routines int) []int {
-	raw := c.Get("tun.cpu_affinity")
-	if raw == nil {
-		return nil
-	}
-	rv, ok := raw.([]any)
-	if !ok {
-		l.Warn("tun.cpu_affinity must be a list of integers; ignoring", "value", raw)
-		return nil
-	}
-	nCPU := runtime.NumCPU()
-	cpus := make([]int, 0, len(rv))
-	for i, e := range rv {
-		var cpu int
-		switch v := e.(type) {
-		case int:
-			cpu = v
-		case int64:
-			cpu = int(v)
-		case float64:
-			cpu = int(v)
-		default:
-			l.Warn("tun.cpu_affinity entry not an integer; ignoring affinity",
-				"index", i, "value", e)
-			return nil
-		}
-		if cpu < 0 || cpu >= nCPU {
-			l.Warn("tun.cpu_affinity entry out of range; ignoring affinity",
-				"index", i, "cpu", cpu, "num_cpu", nCPU)
-			return nil
-		}
-		cpus = append(cpus, cpu)
-	}
-	if len(cpus) != routines {
-		l.Warn("tun.cpu_affinity length doesn't match routines; queues will modulo-cycle through the list",
-			"affinity_len", len(cpus), "routines", routines)
-	}
-	return cpus
-}
-
 func moduleVersion() string {
 	info, ok := debug.ReadBuildInfo()
 	if !ok {

message_metrics.go

@@ -13,8 +13,6 @@ type MessageMetrics struct {
 
 	rxUnknown metrics.Counter
 	txUnknown metrics.Counter
-
-	rxInvalid metrics.Counter
 }
 
 func (m *MessageMetrics) Rx(t header.MessageType, s header.MessageSubType, i int64) {
@@ -35,11 +33,6 @@ func (m *MessageMetrics) Tx(t header.MessageType, s header.MessageSubType, i int
 		}
 	}
 }
-func (m *MessageMetrics) RxInvalid(i int64) {
-	if m != nil && m.rxInvalid != nil {
-		m.rxInvalid.Inc(i)
-	}
-}
 
 func newMessageMetrics() *MessageMetrics {
 	gen := func(t string) [][]metrics.Counter {
@@ -63,7 +56,6 @@ func newMessageMetrics() *MessageMetrics {
 
 		rxUnknown: metrics.GetOrRegisterCounter("messages.rx.other", nil),
 		txUnknown: metrics.GetOrRegisterCounter("messages.tx.other", nil),
-		rxInvalid: metrics.GetOrRegisterCounter("messages.rx.invalid", nil),
 	}
 }
 

noise.go

@@ -0,0 +1,86 @@
+package nebula
+
+import (
+	"crypto/cipher"
+	"encoding/binary"
+	"errors"
+
+	"github.com/flynn/noise"
+)
+
+type endianness interface {
+	PutUint64(b []byte, v uint64)
+}
+
+var noiseEndianness endianness = binary.BigEndian
+
+// NonceSize is the AEAD nonce length used by all ciphers nebula supports
+// today (AES-GCM and ChaCha20-Poly1305 both use 96-bit nonces). Encrypt-
+// and DecryptDanger lay out the nonce as 4 zero bytes followed by an 8-byte
+// big-endian counter; if a future cipher with a different nonce size is
+// added, this constant and those layouts must change together.
+const NonceSize = 12
+
+// AEADOverhead is the AEAD authentication tag length the ciphers nebula
+// supports append to ciphertext. Both AES-GCM and ChaCha20-Poly1305 use
+// 128-bit tags. NebulaCipherState.Overhead() returns this dynamically from
+// the cipher; the constant is for sizing buffers at construction time.
+const AEADOverhead = 16
+
+type NebulaCipherState struct {
+	c cipher.AEAD
+}
+
+func NewNebulaCipherState(s *noise.CipherState) *NebulaCipherState {
+	x := s.Cipher()
+	return &NebulaCipherState{c: x.(cipher.AEAD)}
+}
+
+// EncryptDanger encrypts and authenticates a given payload.
+//
+// out is a destination slice to hold the output of the EncryptDanger operation.
+//   - ad is additional data, which will be authenticated and appended to out, but not encrypted.
+//   - plaintext is encrypted, authenticated and appended to out.
+//   - n is a nonce value which must never be re-used with this key.
+//   - nb is a buffer used for temporary storage in the implementation of this call, which should
+//     be re-used by callers to minimize garbage collection.
+func (s *NebulaCipherState) EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error) {
+	if s != nil {
+		// TODO: Is this okay now that we have made messageCounter atomic?
+		// Alternative may be to split the counter space into ranges
+		//if n <= s.n {
+		//	return nil, errors.New("CRITICAL: a duplicate counter value was used")
+		//}
+		//s.n = n
+		nb[0] = 0
+		nb[1] = 0
+		nb[2] = 0
+		nb[3] = 0
+		noiseEndianness.PutUint64(nb[4:], n)
+		out = s.c.Seal(out, nb, plaintext, ad)
+		//l.Debugf("Encryption: outlen: %d, nonce: %d, ad: %s, plainlen %d", len(out), n, ad, len(plaintext))
+		return out, nil
+	} else {
+		return nil, errors.New("no cipher state available to encrypt")
+	}
+}
+
+func (s *NebulaCipherState) DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error) {
+	if s != nil {
+		nb[0] = 0
+		nb[1] = 0
+		nb[2] = 0
+		nb[3] = 0
+		noiseEndianness.PutUint64(nb[4:], n)
+		return s.c.Open(out, nb, ciphertext, ad)
+	} else {
+		return []byte{}, nil
+	}
+}
+
+func (s *NebulaCipherState) Overhead() int {
+	if s != nil {
+		return s.c.Overhead()
+	}
+	return 0
+}

noiseutil/aesgcm.go

@@ -1,53 +0,0 @@
-package noiseutil
-
-import (
-	"crypto/cipher"
-	"encoding/binary"
-	"errors"
-
-	"github.com/flynn/noise"
-)
-
-// CipherStateAESGCM is the data-plane wrapper for the AES-GCM AEAD cipher.
-// AES-GCM uses big-endian nonce encoding per the Noise spec.
-type CipherStateAESGCM struct {
-	c cipher.AEAD
-}
-
-// NewCipherStateAESGCM extracts the underlying AEAD from the post-handshake noise.CipherState.
-// The caller is responsible for ensuring the noise cipher is actually AES-GCM,
-// otherwise the type assertion still succeeds but the nonce endianness will be wrong on the wire.
-func NewCipherStateAESGCM(s *noise.CipherState) *CipherStateAESGCM {
-	return &CipherStateAESGCM{c: s.Cipher().(cipher.AEAD)}
-}
-
-func (s *CipherStateAESGCM) EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error) {
-	if s == nil {
-		return nil, errors.New("no cipher state available to encrypt")
-	}
-	nb[0] = 0
-	nb[1] = 0
-	nb[2] = 0
-	nb[3] = 0
-	binary.BigEndian.PutUint64(nb[4:], n)
-	return s.c.Seal(out, nb, plaintext, ad), nil
-}
-
-func (s *CipherStateAESGCM) DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error) {
-	if s == nil {
-		return []byte{}, nil
-	}
-	nb[0] = 0
-	nb[1] = 0
-	nb[2] = 0
-	nb[3] = 0
-	binary.BigEndian.PutUint64(nb[4:], n)
-	return s.c.Open(out, nb, ciphertext, ad)
-}
-
-func (s *CipherStateAESGCM) Overhead() int {
-	if s == nil {
-		return 0
-	}
-	return s.c.Overhead()
-}

noiseutil/chachapoly.go

@@ -1,52 +0,0 @@
-package noiseutil
-
-import (
-	"crypto/cipher"
-	"encoding/binary"
-	"errors"
-
-	"github.com/flynn/noise"
-)
-
-// CipherStateChaChaPoly is the data-plane wrapper for the ChaCha20-Poly1305 AEAD cipher.
-// ChaCha20-Poly1305 uses little-endian nonce encoding per the Noise spec.
-type CipherStateChaChaPoly struct {
-	c cipher.AEAD
-}
-
-// NewCipherStateChaChaPoly extracts the underlying AEAD from the post-handshake noise.CipherState.
-// The caller is responsible for ensuring the noise cipher is actually ChaCha20-Poly1305.
-func NewCipherStateChaChaPoly(s *noise.CipherState) *CipherStateChaChaPoly {
-	return &CipherStateChaChaPoly{c: s.Cipher().(cipher.AEAD)}
-}
-
-func (s *CipherStateChaChaPoly) EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error) {
-	if s == nil {
-		return nil, errors.New("no cipher state available to encrypt")
-	}
-	nb[0] = 0
-	nb[1] = 0
-	nb[2] = 0
-	nb[3] = 0
-	binary.LittleEndian.PutUint64(nb[4:], n)
-	return s.c.Seal(out, nb, plaintext, ad), nil
-}
-
-func (s *CipherStateChaChaPoly) DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error) {
-	if s == nil {
-		return []byte{}, nil
-	}
-	nb[0] = 0
-	nb[1] = 0
-	nb[2] = 0
-	nb[3] = 0
-	binary.LittleEndian.PutUint64(nb[4:], n)
-	return s.c.Open(out, nb, ciphertext, ad)
-}
-
-func (s *CipherStateChaChaPoly) Overhead() int {
-	if s == nil {
-		return 0
-	}
-	return s.c.Overhead()
-}

noiseutil/cipher_state.go

@@ -1,40 +0,0 @@
-package noiseutil
-
-import (
-	"fmt"
-
-	"github.com/flynn/noise"
-)
-
-// CipherState is the post-handshake AEAD cipher used for the data plane.
-// Each supported cipher has its own concrete implementation in this package with the nonce endianness hardcoded,
-// so the encrypt/decrypt fast path avoids interface dispatch on the byte order.
-type CipherState interface {
-	// EncryptDanger encrypts and authenticates a given payload.
-	//
-	// out is a destination slice to hold the output of the EncryptDanger operation.
-	//   - ad is additional data, which will be authenticated and appended to out, but not encrypted.
-	//   - plaintext is encrypted, authenticated and appended to out.
-	//   - n is a nonce value which must never be re-used with this key.
-	//   - nb is a scratch buffer used to assemble the nonce.
-	EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error)
-
-	// DecryptDanger authenticates and decrypts a given payload, with the same argument shape as EncryptDanger.
-	DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error)
-
-	// Overhead returns the AEAD tag size, or 0 if the receiver is nil.
-	Overhead() int
-}
-
-// NewCipherState wraps the post-handshake noise.CipherState in the per-cipher type that matches cipherFunc.
-// cipherFunc must be the same cipher used to build the noise CipherSuite that produced s.
-func NewCipherState(s *noise.CipherState, cipherFunc noise.CipherFunc) CipherState {
-	switch cipherFunc.CipherName() {
-	case CipherAESGCM.CipherName():
-		return NewCipherStateAESGCM(s)
-	case noise.CipherChaChaPoly.CipherName():
-		return NewCipherStateChaChaPoly(s)
-	default:
-		panic(fmt.Sprintf("noiseutil: unsupported cipher %q", cipherFunc.CipherName()))
-	}
-}

noiseutil/cipher_state_test.go

@@ -1,166 +0,0 @@
-package noiseutil
-
-import (
-	"testing"
-
-	"github.com/flynn/noise"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-func TestCipherStateAESGCMRoundtrip(t *testing.T) {
-	enc, dec := buildCipherStates(t, CipherAESGCM)
-	roundtrip(t, NewCipherStateAESGCM(enc), NewCipherStateAESGCM(dec))
-}
-
-func TestCipherStateChaChaPolyRoundtrip(t *testing.T) {
-	enc, dec := buildCipherStates(t, noise.CipherChaChaPoly)
-	roundtrip(t, NewCipherStateChaChaPoly(enc), NewCipherStateChaChaPoly(dec))
-}
-
-func TestNewCipherStateDispatch(t *testing.T) {
-	encA, _ := buildCipherStates(t, CipherAESGCM)
-	encC, _ := buildCipherStates(t, noise.CipherChaChaPoly)
-
-	assert.IsType(t, &CipherStateAESGCM{}, NewCipherState(encA, CipherAESGCM))
-	assert.IsType(t, &CipherStateChaChaPoly{}, NewCipherState(encC, noise.CipherChaChaPoly))
-}
-
-func TestNewCipherStateUnsupportedPanics(t *testing.T) {
-	enc, _ := buildCipherStates(t, CipherAESGCM)
-	assert.Panics(t, func() {
-		NewCipherState(enc, fakeCipher{})
-	})
-}
-
-type fakeCipher struct{}
-
-func (fakeCipher) Cipher(k [32]byte) noise.Cipher { return nil }
-func (fakeCipher) CipherName() string             { return "Fake" }
-
-// buildCipherStates runs an in-memory NN handshake with the requested cipher
-// to produce a pair of post-handshake CipherStates that share keys.
-func buildCipherStates(t *testing.T, c noise.CipherFunc) (*noise.CipherState, *noise.CipherState) {
-	t.Helper()
-	suite := noise.NewCipherSuite(noise.DH25519, c, noise.HashSHA256)
-	cfg := noise.Config{CipherSuite: suite, Pattern: noise.HandshakeNN}
-	cfg.Initiator = true
-	hsI, err := noise.NewHandshakeState(cfg)
-	require.NoError(t, err)
-	cfg.Initiator = false
-	hsR, err := noise.NewHandshakeState(cfg)
-	require.NoError(t, err)
-
-	msg, _, _, err := hsI.WriteMessage(nil, nil)
-	require.NoError(t, err)
-	_, _, _, err = hsR.ReadMessage(nil, msg)
-	require.NoError(t, err)
-
-	msg, dR, _, err := hsR.WriteMessage(nil, nil)
-	require.NoError(t, err)
-	_, eI, _, err := hsI.ReadMessage(nil, msg)
-	require.NoError(t, err)
-	require.NotNil(t, eI)
-	require.NotNil(t, dR)
-
-	// noise returns (cs1, cs2) where cs1 is the initiator->responder cipher.
-	return eI, dR
-}
-
-func roundtrip(t *testing.T, enc, dec CipherState) {
-	t.Helper()
-	plaintext := []byte("nebula cipher state roundtrip")
-	ad := []byte("aad")
-	nb := make([]byte, 12)
-
-	ct, err := enc.EncryptDanger(nil, ad, plaintext, 1, nb)
-	require.NoError(t, err)
-	assert.NotEqual(t, plaintext, ct)
-
-	pt, err := dec.DecryptDanger(nil, ad, ct, 1, nb)
-	require.NoError(t, err)
-	assert.Equal(t, plaintext, pt)
-
-	// Wrong nonce must fail authentication.
-	_, err = dec.DecryptDanger(nil, ad, ct, 2, nb)
-	require.Error(t, err)
-
-	assert.Equal(t, enc.Overhead(), dec.Overhead())
-	assert.Equal(t, 16, enc.Overhead())
-}
-
-func BenchmarkCipherStateEncryptAESGCM(b *testing.B) {
-	enc, _ := buildCipherStatesB(b, CipherAESGCM)
-	benchEncryptCipherState(b, NewCipherState(enc, CipherAESGCM))
-}
-
-func BenchmarkCipherStateEncryptChaChaPoly(b *testing.B) {
-	enc, _ := buildCipherStatesB(b, noise.CipherChaChaPoly)
-	benchEncryptCipherState(b, NewCipherState(enc, noise.CipherChaChaPoly))
-}
-
-func benchEncryptCipherState(b *testing.B, cs CipherState) {
-	plaintext := make([]byte, 1280)
-	ad := make([]byte, 16)
-	nb := make([]byte, 12)
-	out := make([]byte, 0, len(plaintext)+cs.Overhead())
-	b.ResetTimer()
-	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
-		var err error
-		out, err = cs.EncryptDanger(out[:0], ad, plaintext, uint64(i+1), nb)
-		if err != nil {
-			b.Fatal(err)
-		}
-	}
-}
-
-func buildCipherStatesB(b *testing.B, c noise.CipherFunc) (*noise.CipherState, *noise.CipherState) {
-	b.Helper()
-	suite := noise.NewCipherSuite(noise.DH25519, c, noise.HashSHA256)
-	cfg := noise.Config{CipherSuite: suite, Pattern: noise.HandshakeNN}
-	cfg.Initiator = true
-	hsI, err := noise.NewHandshakeState(cfg)
-	if err != nil {
-		b.Fatal(err)
-	}
-	cfg.Initiator = false
-	hsR, err := noise.NewHandshakeState(cfg)
-	if err != nil {
-		b.Fatal(err)
-	}
-	msg, _, _, err := hsI.WriteMessage(nil, nil)
-	if err != nil {
-		b.Fatal(err)
-	}
-	if _, _, _, err := hsR.ReadMessage(nil, msg); err != nil {
-		b.Fatal(err)
-	}
-	msg, dR, _, err := hsR.WriteMessage(nil, nil)
-	if err != nil {
-		b.Fatal(err)
-	}
-	_, eI, _, err := hsI.ReadMessage(nil, msg)
-	if err != nil {
-		b.Fatal(err)
-	}
-	return eI, dR
-}
-
-func TestCipherStateNilSafety(t *testing.T) {
-	var aes *CipherStateAESGCM
-	_, err := aes.EncryptDanger(nil, nil, nil, 0, make([]byte, 12))
-	require.Error(t, err)
-	out, err := aes.DecryptDanger(nil, nil, nil, 0, make([]byte, 12))
-	require.NoError(t, err)
-	assert.Empty(t, out)
-	assert.Equal(t, 0, aes.Overhead())
-
-	var cc *CipherStateChaChaPoly
-	_, err = cc.EncryptDanger(nil, nil, nil, 0, make([]byte, 12))
-	require.Error(t, err)
-	out, err = cc.DecryptDanger(nil, nil, nil, 0, make([]byte, 12))
-	require.NoError(t, err)
-	assert.Empty(t, out)
-	assert.Equal(t, 0, cc.Overhead())
-}

outside.go

@@ -2,57 +2,42 @@ package nebula
 
 import (
 	"context"
+	"encoding/binary"
 	"errors"
 	"log/slog"
 	"net/netip"
 	"time"
 
+	"github.com/google/gopacket/layers"
+	"golang.org/x/net/ipv6"
+
 	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/header"
-	"github.com/slackhq/nebula/overlay/batch"
-	"github.com/slackhq/nebula/udp"
+	"golang.org/x/net/ipv4"
 )
 
-var ErrOutOfWindow = errors.New("out of window packet")
+const (
+	minFwPacketLen = 4
+)
 
-func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, parsedRx *batch.RxParsed, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
+func (f *Interface) readOutsidePackets(via ViaSender, buf *WireBuffer, packet []byte, lhf *LightHouseHandler, q int, localCache firewall.ConntrackCache) {
+	h := buf.H
 	err := h.Parse(packet)
 	if err != nil {
 		// Hole punch packets are 0 or 1 byte big, so lets ignore printing those errors
-		// TODO: record metrics for rx holepunch/punchy packets?
 		if len(packet) > 1 {
-			f.messageMetrics.RxInvalid(1)
-			if f.l.Enabled(context.Background(), slog.LevelDebug) {
-				f.l.Debug("Error while parsing inbound packet",
-					"from", via,
-					"error", err,
-					"packet", packet,
-				)
-			}
-		}
-		return
-	}
-
-	if h.Version != header.Version {
-		f.messageMetrics.RxInvalid(1)
-		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			f.l.Debug("Unexpected header version received", "from", via)
-		}
-		return
-	}
-
-	// Check before processing to see if this is a expected type/subtype
-	if !h.IsValidSubType() {
-		f.messageMetrics.RxInvalid(1)
-		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			f.l.Debug("Unexpected packet received", "from", via)
+			f.l.Info("Error while parsing inbound packet",
+				"from", via,
+				"error", err,
+				"packet", packet,
+			)
 		}
 		return
 	}
 
+	//l.Error("in packet ", header, packet[HeaderLen:])
 	if !via.IsRelayed {
 		if f.myVpnNetworksTable.Contains(via.UdpAddr.Addr()) {
-			f.messageMetrics.RxInvalid(1)
 			if f.l.Enabled(context.Background(), slog.LevelDebug) {
 				f.l.Debug("Refusing to process double encrypted packet", "from", via)
 			}
@@ -60,193 +45,217 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 		}
 	}
 
-	// don't keep Rx metrics for message type, since you can see those in the tun metrics
-	if h.Type != header.Message {
-		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
-	}
-
-	// Unencrypted packets
-	switch h.Type {
-	case header.Handshake:
-		f.handshakeManager.HandleIncoming(via, packet, h)
-		return
-
-	case header.RecvError:
-		f.handleRecvError(via.UdpAddr, h)
-		return
-	}
-
-	// Relay packets are special
-	isMessageRelay := (h.Type == header.Message && h.Subtype == header.MessageRelay)
-
 	var hostinfo *HostInfo
-	if isMessageRelay {
+	// verify if we've seen this index before, otherwise respond to the handshake initiation
+	if h.Type == header.Message && h.Subtype == header.MessageRelay {
 		hostinfo = f.hostMap.QueryRelayIndex(h.RemoteIndex)
 	} else {
 		hostinfo = f.hostMap.QueryIndex(h.RemoteIndex)
 	}
 
-	// At this point we should have a valid existing tunnel, verify and send
-	// recvError if necessary
-	if hostinfo == nil || hostinfo.ConnectionState == nil {
-		if !via.IsRelayed {
-			f.maybeSendRecvError(via.UdpAddr, h.RemoteIndex)
-		}
-		return
+	var ci *ConnectionState
+	if hostinfo != nil {
+		ci = hostinfo.ConnectionState
 	}
 
-	// All remaining packets are encrypted
-	ci := hostinfo.ConnectionState
-	if !ci.window.Check(f.l, h.MessageCounter) {
-		return
-	}
-
-	// Relay packets are special
-	if isMessageRelay {
-		f.handleOutsideRelayPacket(hostinfo, via, out, packet, h, fwPacket, parsedRx, lhf, nb, q, localCache, meta)
-
-		return
-	}
-
-	out, err = f.decrypt(hostinfo, h.MessageCounter, out, packet, h, nb)
-	if err != nil {
-		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("Failed to decrypt packet",
-				"error", err,
-				"from", via,
-				"header", h,
-			)
-		}
-		return
-	}
-
-	// Roam before we respond
-	f.handleHostRoaming(hostinfo, via)
-	f.connectionManager.In(hostinfo)
-
 	switch h.Type {
 	case header.Message:
+		if !f.handleEncrypted(ci, via, h) {
+			return
+		}
+
 		switch h.Subtype {
 		case header.MessageNone:
-			f.handleOutsideMessagePacket(hostinfo, out, packet, fwPacket, parsedRx, nb, q, localCache, meta)
-		default:
-			hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected message subtype seen", "from", via, "header", h)
-			return
+			if !f.decryptToTun(hostinfo, h.MessageCounter, buf, packet, q, localCache) {
+				return
+			}
+		case header.MessageRelay:
+			// The entire body is sent as AD, not encrypted.
+			// The packet consists of a 16-byte parsed Nebula header, Associated Data-protected payload, and a trailing 16-byte AEAD signature value.
+			// The packet is guaranteed to be at least 16 bytes at this point, b/c it got past the h.Parse() call above. If it's
+			// otherwise malformed (meaning, there is no trailing 16 byte AEAD value), then this will result in at worst a 0-length slice
+			// which will gracefully fail in the DecryptDanger call.
+			signedPayload := packet[:len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
+			signatureValue := packet[len(packet)-hostinfo.ConnectionState.dKey.Overhead():]
+			// AAD-only validation: passing dst=nil since there's no plaintext
+			// to recover (ciphertext is just the trailing AEAD tag).
+			if _, err = hostinfo.ConnectionState.dKey.DecryptDanger(nil, signedPayload, signatureValue, h.MessageCounter, buf.NB); err != nil {
+				return
+			}
+			// Successfully validated the thing. Get rid of the Relay header.
+			signedPayload = signedPayload[header.Len:]
+			// Pull the Roaming parts up here, and return in all call paths.
+			f.handleHostRoaming(hostinfo, via)
+			// Track usage of both the HostInfo and the Relay for the received & authenticated packet
+			f.connectionManager.In(hostinfo)
+			f.connectionManager.RelayUsed(h.RemoteIndex)
+
+			relay, ok := hostinfo.relayState.QueryRelayForByIdx(h.RemoteIndex)
+			if !ok {
+				// The only way this happens is if hostmap has an index to the correct HostInfo, but the HostInfo is missing
+				// its internal mapping. This should never happen.
+				hostinfo.logger(f.l).Error("HostInfo missing remote relay index",
+					"vpnAddrs", hostinfo.vpnAddrs,
+					"remoteIndex", h.RemoteIndex,
+				)
+				return
+			}
+
+			switch relay.Type {
+			case TerminalType:
+				// If I am the target of this relay, process the unwrapped packet
+				// From this recursive point, all these variables are 'burned'. We shouldn't rely on them again.
+				via = ViaSender{
+					UdpAddr:   via.UdpAddr,
+					relayHI:   hostinfo,
+					remoteIdx: relay.RemoteIndex,
+					relay:     relay,
+					IsRelayed: true,
+				}
+				buf.Reset()
+				f.readOutsidePackets(via, buf, signedPayload, lhf, q, localCache)
+				return
+			case ForwardingType:
+				// Find the target HostInfo relay object
+				targetHI, targetRelay, err := f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relay.PeerAddr)
+				if err != nil {
+					hostinfo.logger(f.l).Info("Failed to find target host info by ip",
+						"relayTo", relay.PeerAddr,
+						"error", err,
+						"hostinfo.vpnAddrs", hostinfo.vpnAddrs,
+					)
+					return
+				}
+
+				// If that relay is Established, forward the payload through it
+				if targetRelay.State == Established {
+					switch targetRelay.Type {
+					case ForwardingType:
+						// Forward this packet through the relay tunnel
+						// Find the target HostInfo
+						f.SendVia(targetHI, targetRelay, signedPayload, buf)
+						return
+					case TerminalType:
+						hostinfo.logger(f.l).Error("Unexpected Relay Type of Terminal")
+					}
+				} else {
+					hostinfo.logger(f.l).Info("Unexpected target relay state",
+						"relayTo", relay.PeerAddr,
+						"relayFrom", hostinfo.vpnAddrs[0],
+						"targetRelayState", targetRelay.State,
+					)
+					return
+				}
+			}
 		}
 
 	case header.LightHouse:
+		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
+		if !f.handleEncrypted(ci, via, h) {
+			return
+		}
+
+		d, err := f.decrypt(hostinfo, h.MessageCounter, buf, packet, h)
+		if err != nil {
+			hostinfo.logger(f.l).Error("Failed to decrypt lighthouse packet",
+				"error", err,
+				"from", via,
+				"packet", packet,
+			)
+			return
+		}
+
 		//TODO: assert via is not relayed
-		lhf.HandleRequest(via.UdpAddr, hostinfo.vpnAddrs, out, f)
+		lhf.HandleRequest(via.UdpAddr, hostinfo.vpnAddrs, d, f)
+
+		// Fallthrough to the bottom to record incoming traffic
 
 	case header.Test:
-		switch h.Subtype {
-		case header.TestReply:
-			// No-op, useful for the Roaming and connectionManager side-effects above
-		case header.TestRequest:
-			f.send(header.Test, header.TestReply, ci, hostinfo, out, nb, out)
-		default:
-			hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected test subtype seen", "from", via, "header", h)
+		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
+		if !f.handleEncrypted(ci, via, h) {
 			return
 		}
 
+		d, err := f.decrypt(hostinfo, h.MessageCounter, buf, packet, h)
+		if err != nil {
+			hostinfo.logger(f.l).Error("Failed to decrypt test packet",
+				"error", err,
+				"from", via,
+				"packet", packet,
+			)
+			return
+		}
+
+		if h.Subtype == header.TestRequest {
+			// This testRequest might be from TryPromoteBest, so we should roam
+			// to the new IP address before responding.
+			f.handleHostRoaming(hostinfo, via)
+			f.send(header.Test, header.TestReply, ci, hostinfo, d, buf)
+		}
+
+		// Fallthrough to the bottom to record incoming traffic
+
+		// Non encrypted messages below here, they should not fall through to avoid tracking incoming traffic since they
+		// are unauthenticated
+
+	case header.Handshake:
+		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
+		f.handshakeManager.HandleIncoming(via, packet, h)
+		return
+
+	case header.RecvError:
+		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
+		f.handleRecvError(via.UdpAddr, h)
+		return
+
 	case header.CloseTunnel:
+		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
+		if !f.handleEncrypted(ci, via, h) {
+			return
+		}
+		_, err = f.decrypt(hostinfo, h.MessageCounter, buf, packet, h)
+		if err != nil {
+			hostinfo.logger(f.l).Error("Failed to decrypt CloseTunnel packet",
+				"error", err,
+				"from", via,
+				"packet", packet,
+			)
+			return
+		}
+
 		hostinfo.logger(f.l).Info("Close tunnel received, tearing down.", "from", via)
+
 		f.closeTunnel(hostinfo)
+		return
 
 	case header.Control:
-		f.relayManager.HandleControlMsg(hostinfo, out, f)
-
-	default:
-		hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected message type seen", "from", via, "header", h)
-	}
-}
-
-func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, parsedRx *batch.RxParsed, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
-	// The entire body is sent as AD, not encrypted.
-	// The packet consists of a 16-byte parsed Nebula header, Associated Data-protected payload, and a trailing 16-byte AEAD signature value.
-	// The packet is guaranteed to be at least 16 bytes at this point, b/c it got past the h.Parse() call above. If it's
-	// otherwise malformed (meaning, there is no trailing 16 byte AEAD value), then this will result in at worst a 0-length slice
-	// which will gracefully fail in the DecryptDanger call.
-	signedPayload := packet[:len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
-	signatureValue := packet[len(packet)-hostinfo.ConnectionState.dKey.Overhead():]
-	var err error
-	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, signedPayload, signatureValue, h.MessageCounter, nb)
-	if err != nil {
-		return
-	}
-	// Successfully validated the thing. Get rid of the Relay header.
-	signedPayload = signedPayload[header.Len:]
-	// Pull the Roaming parts up here, and return in all call paths.
-	f.handleHostRoaming(hostinfo, via)
-	// Track usage of both the HostInfo and the Relay for the received & authenticated packet
-	f.connectionManager.In(hostinfo)
-	f.connectionManager.RelayUsed(h.RemoteIndex)
-
-	relay, ok := hostinfo.relayState.QueryRelayForByIdx(h.RemoteIndex)
-	if !ok {
-		// The only way this happens is if hostmap has an index to the correct HostInfo, but the HostInfo is missing
-		// its internal mapping. This should never happen.
-		hostinfo.logger(f.l).Error("HostInfo missing remote relay index",
-			"vpnAddrs", hostinfo.vpnAddrs,
-			"remoteIndex", h.RemoteIndex,
-		)
-		return
-	}
-
-	switch relay.Type {
-	case TerminalType:
-		// If I am the target of this relay, process the unwrapped packet
-		// From this recursive point, all these variables are 'burned'. We shouldn't rely on them again.
-		via = ViaSender{
-			UdpAddr:   via.UdpAddr,
-			relayHI:   hostinfo,
-			remoteIdx: relay.RemoteIndex,
-			relay:     relay,
-			IsRelayed: true,
+		if !f.handleEncrypted(ci, via, h) {
+			return
 		}
-		f.readOutsidePackets(via, out[:0], signedPayload, h, fwPacket, parsedRx, lhf, nb, q, localCache, meta)
-		return
-	case ForwardingType:
-		// Find the target HostInfo relay object
-		targetHI, targetRelay, err := f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relay.PeerAddr)
+
+		d, err := f.decrypt(hostinfo, h.MessageCounter, buf, packet, h)
 		if err != nil {
-			hostinfo.logger(f.l).Info("Failed to find target host info by ip",
-				"relayTo", relay.PeerAddr,
+			hostinfo.logger(f.l).Error("Failed to decrypt Control packet",
 				"error", err,
-				"hostinfo.vpnAddrs", hostinfo.vpnAddrs,
+				"from", via,
+				"packet", packet,
 			)
 			return
 		}
 
-		// If that relay is Established, forward the payload through it
-		if targetRelay.State == Established {
-			switch targetRelay.Type {
-			case ForwardingType:
-				// Forward this packet through the relay tunnel
-				// Find the target HostInfo //todo it would potentially be nice to batch these
-				f.SendVia(targetHI, targetRelay, signedPayload, nb, out, false)
-			case TerminalType:
-				hostinfo.logger(f.l).Error("Unexpected Relay Type of Terminal")
-				return
-			default:
-				if f.l.Enabled(context.Background(), slog.LevelDebug) {
-					hostinfo.logger(f.l).Debug("Unexpected targetRelay Type", "from", via, "relayType", targetRelay.Type)
-				}
-				return
-			}
-		} else {
-			hostinfo.logger(f.l).Info("Unexpected target relay state",
-				"relayTo", relay.PeerAddr,
-				"relayFrom", hostinfo.vpnAddrs[0],
-				"targetRelayState", targetRelay.State,
-			)
-			return
-		}
+		f.relayManager.HandleControlMsg(hostinfo, d, f)
+
 	default:
+		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("Unexpected relay type", "from", via, "relayType", relay.Type)
+			hostinfo.logger(f.l).Debug("Unexpected packet received", "from", via)
 		}
+		return
 	}
+
+	f.handleHostRoaming(hostinfo, via)
+
+	f.connectionManager.In(hostinfo)
 }
 
 // closeTunnel closes a tunnel locally, it does not send a closeTunnel packet to the remote
@@ -260,7 +269,9 @@ func (f *Interface) closeTunnel(hostInfo *HostInfo) {
 
 // sendCloseTunnel is a helper function to send a proper close tunnel packet to a remote
 func (f *Interface) sendCloseTunnel(h *HostInfo) {
-	f.send(header.CloseTunnel, 0, h.ConnectionState, h, []byte{}, make([]byte, 12, 12), make([]byte, mtu))
+	buf := f.bufAlloc.Acquire()
+	defer f.bufAlloc.Release(buf)
+	f.send(header.CloseTunnel, 0, h.ConnectionState, h, []byte{}, buf)
 }
 
 func (f *Interface) handleHostRoaming(hostinfo *HostInfo, via ViaSender) {
@@ -294,6 +305,23 @@ func (f *Interface) handleHostRoaming(hostinfo *HostInfo, via ViaSender) {
 
 }
 
+// handleEncrypted returns true if a packet should be processed, false otherwise
+func (f *Interface) handleEncrypted(ci *ConnectionState, via ViaSender, h *header.H) bool {
+	// If connectionstate does not exist, send a recv error, if possible, to encourage a fast reconnect
+	if ci == nil {
+		if !via.IsRelayed {
+			f.maybeSendRecvError(via.UdpAddr, h.RemoteIndex)
+		}
+		return false
+	}
+	// If the window check fails, refuse to process the packet, but don't send a recv error
+	if !ci.window.Check(f.l, h.MessageCounter) {
+		return false
+	}
+
+	return true
+}
+
 var (
 	ErrPacketTooShort          = errors.New("packet is too short")
 	ErrUnknownIPVersion        = errors.New("packet is an unknown ip version")
@@ -304,121 +332,253 @@ var (
 )
 
 // newPacket validates and parses the interesting bits for the firewall out of the ip and sub protocol headers
-// newPacket parses data into a fully-hydrated firewall.Packet — kept as a
-// thin wrapper around newPacketKey + Hydrate so there's one source of
-// parse logic. Callers that don't need the netip.Addr-rich form (e.g.
-// conntrack-only paths) should use newPacketKey directly.
 func newPacket(data []byte, incoming bool, fp *firewall.Packet) error {
-	var parsed batch.RxParsed
-	if err := batch.ParsePacket(data, incoming, &parsed); err != nil {
-		return err
+	if len(data) < 1 {
+		return ErrPacketTooShort
 	}
-	parsed.Key.Hydrate(fp)
+
+	version := int((data[0] >> 4) & 0x0f)
+	switch version {
+	case ipv4.Version:
+		return parseV4(data, incoming, fp)
+	case ipv6.Version:
+		return parseV6(data, incoming, fp)
+	}
+	return ErrUnknownIPVersion
+}
+
+func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
+	dataLen := len(data)
+	if dataLen < ipv6.HeaderLen {
+		return ErrIPv6PacketTooShort
+	}
+
+	if incoming {
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[8:24])
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[24:40])
+	} else {
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[8:24])
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[24:40])
+	}
+
+	protoAt := 6             // NextHeader is at 6 bytes into the ipv6 header
+	offset := ipv6.HeaderLen // Start at the end of the ipv6 header
+	next := 0
+	for {
+		if protoAt >= dataLen {
+			break
+		}
+		proto := layers.IPProtocol(data[protoAt])
+
+		switch proto {
+		case layers.IPProtocolESP, layers.IPProtocolNoNextHeader:
+			fp.Protocol = uint8(proto)
+			fp.RemotePort = 0
+			fp.LocalPort = 0
+			fp.Fragment = false
+			return nil
+
+		case layers.IPProtocolICMPv6:
+			if dataLen < offset+6 {
+				return ErrIPv6PacketTooShort
+			}
+			fp.Protocol = uint8(proto)
+			fp.LocalPort = 0 //incoming vs outgoing doesn't matter for icmpv6
+			icmptype := data[offset+1]
+			switch icmptype {
+			case layers.ICMPv6TypeEchoRequest, layers.ICMPv6TypeEchoReply:
+				fp.RemotePort = binary.BigEndian.Uint16(data[offset+4 : offset+6]) //identifier
+			default:
+				fp.RemotePort = 0
+			}
+			fp.Fragment = false
+			return nil
+
+		case layers.IPProtocolTCP, layers.IPProtocolUDP:
+			if dataLen < offset+4 {
+				return ErrIPv6PacketTooShort
+			}
+
+			fp.Protocol = uint8(proto)
+			if incoming {
+				fp.RemotePort = binary.BigEndian.Uint16(data[offset : offset+2])
+				fp.LocalPort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
+			} else {
+				fp.LocalPort = binary.BigEndian.Uint16(data[offset : offset+2])
+				fp.RemotePort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
+			}
+
+			fp.Fragment = false
+			return nil
+
+		case layers.IPProtocolIPv6Fragment:
+			// Fragment header is 8 bytes, need at least offset+4 to read the offset field
+			if dataLen < offset+8 {
+				return ErrIPv6PacketTooShort
+			}
+
+			// Check if this is the first fragment
+			fragmentOffset := binary.BigEndian.Uint16(data[offset+2:offset+4]) &^ uint16(0x7) // Remove the reserved and M flag bits
+			if fragmentOffset != 0 {
+				// Non-first fragment, use what we have now and stop processing
+				fp.Protocol = data[offset]
+				fp.Fragment = true
+				fp.RemotePort = 0
+				fp.LocalPort = 0
+				return nil
+			}
+
+			// The next loop should be the transport layer since we are the first fragment
+			next = 8 // Fragment headers are always 8 bytes
+
+		case layers.IPProtocolAH:
+			// Auth headers, used by IPSec, have a different meaning for header length
+			if dataLen <= offset+1 {
+				break
+			}
+
+			next = int(data[offset+1]+2) << 2
+
+		default:
+			// Normal ipv6 header length processing
+			if dataLen <= offset+1 {
+				break
+			}
+
+			next = int(data[offset+1]+1) << 3
+		}
+
+		if next <= 0 {
+			// Safety check, each ipv6 header has to be at least 8 bytes
+			next = 8
+		}
+
+		protoAt = offset
+		offset = offset + next
+	}
+
+	return ErrIPv6CouldNotFindPayload
+}
+
+func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
+	// Do we at least have an ipv4 header worth of data?
+	if len(data) < ipv4.HeaderLen {
+		return ErrIPv4PacketTooShort
+	}
+
+	// Adjust our start position based on the advertised ip header length
+	ihl := int(data[0]&0x0f) << 2
+
+	// Well-formed ip header length?
+	if ihl < ipv4.HeaderLen {
+		return ErrIPv4InvalidHeaderLength
+	}
+
+	// Check if this is the second or further fragment of a fragmented packet.
+	flagsfrags := binary.BigEndian.Uint16(data[6:8])
+	fp.Fragment = (flagsfrags & 0x1FFF) != 0
+
+	// Firewall handles protocol checks
+	fp.Protocol = data[9]
+
+	// Accounting for a variable header length, do we have enough data for our src/dst tuples?
+	minLen := ihl
+	if !fp.Fragment {
+		if fp.Protocol == firewall.ProtoICMP {
+			minLen += minFwPacketLen + 2
+		} else {
+			minLen += minFwPacketLen
+		}
+	}
+
+	if len(data) < minLen {
+		return ErrIPv4InvalidHeaderLength
+	}
+
+	if incoming { // Firewall packets are locally oriented
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[12:16])
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[16:20])
+	} else {
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[12:16])
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[16:20])
+	}
+
+	if fp.Fragment {
+		fp.RemotePort = 0
+		fp.LocalPort = 0
+	} else if fp.Protocol == firewall.ProtoICMP { //note that orientation doesn't matter on ICMP
+		fp.RemotePort = binary.BigEndian.Uint16(data[ihl+4 : ihl+6]) //identifier
+		fp.LocalPort = 0                                             //code would be uint16(data[ihl+1])
+	} else if incoming {
+		fp.RemotePort = binary.BigEndian.Uint16(data[ihl : ihl+2])  //src port
+		fp.LocalPort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4]) //dst port
+	} else {
+		fp.LocalPort = binary.BigEndian.Uint16(data[ihl : ihl+2])    //src port
+		fp.RemotePort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4]) //dst port
+	}
+
 	return nil
 }
 
-func (f *Interface) decrypt(hostinfo *HostInfo, mc uint64, out []byte, packet []byte, h *header.H, nb []byte) ([]byte, error) {
-	var err error
-	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], mc, nb)
+func (f *Interface) decrypt(hostinfo *HostInfo, mc uint64, buf *WireBuffer, packet []byte, h *header.H) ([]byte, error) {
+	plaintext, err := buf.DecryptForHandler(hostinfo.ConnectionState, packet, mc)
 	if err != nil {
 		return nil, err
 	}
 
 	if !hostinfo.ConnectionState.window.Update(f.l, mc) {
-		return nil, ErrOutOfWindow
+		if f.l.Enabled(context.Background(), slog.LevelDebug) {
+			hostinfo.logger(f.l).Debug("dropping out of window packet", "header", h)
+		}
+		return nil, errors.New("out of window packet")
 	}
 
-	return out, nil
+	return plaintext, nil
 }
 
-// 2-bit IP-level ECN codepoints (lower bits of IPv4 ToS / IPv6 TC).
-const (
-	ecnNotECT = 0x00
-	ecnECT1   = 0x01
-	ecnECT0   = 0x02
-	ecnCE     = 0x03
-)
-
-// applyOuterECN folds an outer CE mark from the underlay into the inner
-// IP header per RFC 6040 normal mode. It mutates pkt[1] in place. Other
-// codepoints are advisory only and leave the inner unchanged.
-//
-// Merge cases (outer × inner → action):
-//
-//	outer != CE                : no-op (inner is authoritative)
-//	outer == CE, inner Not-ECT : log; cannot propagate to a non-ECN host
-//	outer == CE, inner ECT/CE  : rewrite inner ECN to CE
-func applyOuterECN(pkt []byte, outerECN byte, hostinfo *HostInfo, l *slog.Logger) {
-	if outerECN&ecnCE != ecnCE || len(pkt) < 2 {
-		return
-	}
-	switch pkt[0] >> 4 {
-	case 4:
-		switch pkt[1] & 0x03 {
-		case ecnNotECT:
-			if l.Enabled(context.Background(), slog.LevelDebug) {
-				hostinfo.logger(l).Debug("RFC 6040: outer CE on inner Not-ECT, leaving inner unchanged")
-			}
-		case ecnCE:
-			// Already CE.
-		default:
-			pkt[1] = (pkt[1] &^ 0x03) | ecnCE
-		}
-	case 6:
-		switch (pkt[1] >> 4) & 0x03 {
-		case ecnNotECT:
-			if l.Enabled(context.Background(), slog.LevelDebug) {
-				hostinfo.logger(l).Debug("RFC 6040: outer CE on inner Not-ECT, leaving inner unchanged")
-			}
-		case ecnCE:
-			// Already CE.
-		default:
-			pkt[1] = (pkt[1] &^ 0x30) | (ecnCE << 4)
-		}
-	}
-}
-
-func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, out []byte, packet []byte, fwPacket *firewall.Packet, parsedRx *batch.RxParsed, nb []byte, q int, localCache firewall.ConntrackCache, meta udp.RxMeta) {
-	// RFC 6040 normal-mode combine: fold any outer CE mark stamped by the
-	// underlay into the inner header before firewall + TUN write. Other
-	// outer codepoints are advisory only — we keep the inner unchanged.
-	if f.ecnEnabled.Load() {
-		applyOuterECN(out, meta.OuterECN, hostinfo, f.l)
+func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, buf *WireBuffer, packet []byte, q int, localCache firewall.ConntrackCache) bool {
+	if err := buf.DecryptDatagram(hostinfo.ConnectionState, packet, messageCounter); err != nil {
+		hostinfo.logger(f.l).Error("Failed to decrypt packet", "error", err)
+		return false
 	}
 
-	// Single IP+L4 walk feeds the firewall conntrack key (parsedRx.Key)
-	// and the batcher hint (parsedRx.tcp/udp). Replaces newPacket — and
-	// pointedly does NOT fill fwPacket.LocalAddr/RemoteAddr, since
-	// firewall.Drop's fast path uses Key alone and only hydrates fwPacket
-	// from Key on the slow path.
-	*fwPacket = firewall.Packet{}
-	err := batch.ParsePacket(out, true, parsedRx)
-	if err != nil {
+	ipPacket := buf.IPPacket()
+	if err := newPacket(ipPacket, true, buf.FwPacket); err != nil {
 		hostinfo.logger(f.l).Warn("Error while validating inbound packet",
 			"error", err,
-			"packet", out,
+			"packet", ipPacket,
 		)
-		return
+		return false
 	}
 
-	dropReason := f.firewall.Drop(parsedRx.Key, fwPacket, true, hostinfo, f.pki.GetCAPool(), localCache)
+	if !hostinfo.ConnectionState.window.Update(f.l, messageCounter) {
+		if f.l.Enabled(context.Background(), slog.LevelDebug) {
+			hostinfo.logger(f.l).Debug("dropping out of window packet", "fwPacket", buf.FwPacket)
+		}
+		return false
+	}
+
+	dropReason := f.firewall.Drop(*buf.FwPacket, true, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason != nil {
-		// NOTE: We give `packet` as the `out` here since we already decrypted from it and we don't need it anymore
-		// This gives us a buffer to build the reject packet in
-		f.rejectOutside(out, hostinfo.ConnectionState, hostinfo, nb, packet, q)
+		// NOTE: We hand `packet` (the original UDP ciphertext we already
+		// decrypted from) as the reject-IP scratch since we no longer
+		// need its ciphertext, and it's disjoint from buf.Out where
+		// sendNoMetrics will encrypt the wire packet.
+		f.rejectOutside(ipPacket, hostinfo.ConnectionState, hostinfo, packet, buf, q)
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			hostinfo.logger(f.l).Debug("dropping inbound packet",
-				"fwPacket", fwPacket,
+				"fwPacket", buf.FwPacket,
 				"reason", dropReason,
 			)
 		}
-		return
+		return false
 	}
 
-	err = f.batchers[q].CommitInbound(out, parsedRx)
-	if err != nil {
+	f.connectionManager.In(hostinfo)
+	if _, err := buf.WriteIPToTUN(f.readers[q]); err != nil {
 		f.l.Error("Failed to write to tun", "error", err)
 	}
+	return true
 }
 
 func (f *Interface) maybeSendRecvError(endpoint netip.AddrPort, index uint32) {

outside_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/google/gopacket/layers"
 
 	"github.com/slackhq/nebula/firewall"
-	"github.com/slackhq/nebula/overlay/batch"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/net/ipv4"
@@ -22,13 +21,13 @@ func Test_newPacket(t *testing.T) {
 
 	// length fails
 	err := newPacket([]byte{}, true, p)
-	require.ErrorIs(t, err, batch.ErrPacketTooShort)
+	require.ErrorIs(t, err, ErrPacketTooShort)
 
 	err = newPacket([]byte{0x40}, true, p)
-	require.ErrorIs(t, err, batch.ErrIPv4PacketTooShort)
+	require.ErrorIs(t, err, ErrIPv4PacketTooShort)
 
 	err = newPacket([]byte{0x60}, true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6PacketTooShort)
+	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// length fail with ip options
 	h := ipv4.Header{
@@ -41,15 +40,15 @@ func Test_newPacket(t *testing.T) {
 
 	b, _ := h.Marshal()
 	err = newPacket(b, true, p)
-	require.ErrorIs(t, err, batch.ErrIPv4InvalidHeaderLength)
+	require.ErrorIs(t, err, ErrIPv4InvalidHeaderLength)
 
 	// not an ipv4 packet
 	err = newPacket([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
-	require.ErrorIs(t, err, batch.ErrUnknownIPVersion)
+	require.ErrorIs(t, err, ErrUnknownIPVersion)
 
 	// invalid ihl
 	err = newPacket([]byte{4<<4 | (8 >> 2 & 0x0f), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
-	require.ErrorIs(t, err, batch.ErrIPv4InvalidHeaderLength)
+	require.ErrorIs(t, err, ErrIPv4InvalidHeaderLength)
 
 	// account for variable ip header length - incoming
 	h = ipv4.Header{
@@ -116,7 +115,7 @@ func Test_newPacket_v6(t *testing.T) {
 	require.NoError(t, err)
 
 	err = newPacket(buffer.Bytes(), true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6CouldNotFindPayload)
+	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A v6 packet with a hop-by-hop extension
 	// ICMPv6 Payload (Echo Request)
@@ -150,12 +149,12 @@ func Test_newPacket_v6(t *testing.T) {
 	// A full IPv6 header and 1 byte in the first extension, but missing
 	// the length byte.
 	err = newPacket(buffer.Bytes()[:41], true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6CouldNotFindPayload)
+	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A full IPv6 header plus 1 full extension, but only 1 byte of the
 	// next layer, missing length byte
 	err = newPacket(buffer.Bytes()[:49], true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6CouldNotFindPayload)
+	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 	err = nil
 
 	// A good ICMP packet
@@ -218,7 +217,7 @@ func Test_newPacket_v6(t *testing.T) {
 	b = buffer.Bytes()
 	b[6] = 255 // 255 is a reserved protocol number
 	err = newPacket(b, true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6CouldNotFindPayload)
+	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A good UDP packet
 	ip = layers.IPv6{
@@ -265,7 +264,7 @@ func Test_newPacket_v6(t *testing.T) {
 
 	// Too short UDP packet
 	err = newPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
-	require.ErrorIs(t, err, batch.ErrIPv6PacketTooShort)
+	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// A good TCP packet
 	b[6] = byte(layers.IPProtocolTCP)
@@ -292,7 +291,7 @@ func Test_newPacket_v6(t *testing.T) {
 
 	// Too short TCP packet
 	err = newPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
-	require.ErrorIs(t, err, batch.ErrIPv6PacketTooShort)
+	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// A good UDP packet with an AH header
 	ip = layers.IPv6{
@@ -337,12 +336,12 @@ func Test_newPacket_v6(t *testing.T) {
 
 	// Ensure buffer bounds checking during processing
 	err = newPacket(b[:41], true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6PacketTooShort)
+	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// Invalid AH header
 	b = buffer.Bytes()
 	err = newPacket(b, true, p)
-	require.ErrorIs(t, err, batch.ErrIPv6CouldNotFindPayload)
+	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 }
 
 func Test_newPacket_ipv6Fragment(t *testing.T) {
@@ -449,7 +448,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 
 	// Too short of a fragment packet
 	err = newPacket(secondFrag[:len(secondFrag)-10], false, p)
-	require.ErrorIs(t, err, batch.ErrIPv6PacketTooShort)
+	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 }
 
 func BenchmarkParseV6(b *testing.B) {
@@ -530,7 +529,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("Normal", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = newPacket(normalPacket, true, fp); err != nil {
+			if err = parseV6(normalPacket, true, fp); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -538,7 +537,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("FirstFragment", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = newPacket(firstFrag, true, fp); err != nil {
+			if err = parseV6(firstFrag, true, fp); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -546,7 +545,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("SecondFragment", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = newPacket(secondFrag, true, fp); err != nil {
+			if err = parseV6(secondFrag, true, fp); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -591,7 +590,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("200 HopByHop headers", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = newPacket(evilBytes, false, fp); err != nil {
+			if err = parseV6(evilBytes, false, fp); err != nil {
 				b.Fatal(err)
 			}
 		}

overlay/batch/batch.go

@@ -1,35 +0,0 @@
-package batch
-
-import "net/netip"
-
-type RxBatcher interface {
-	// Reserve creates a pkt to borrow
-	Reserve(sz int) []byte
-	// Commit borrows pkt. The caller must keep pkt valid until the next Flush.
-	// Walks IP+L4 headers itself; prefer CommitInbound when the caller already
-	// has an RxParsed in hand from ParsePacket.
-	Commit(pkt []byte) error
-	// CommitInbound is Commit with a hint produced by ParsePacket, so the
-	// batcher can skip the IP+L4 re-parse. Borrowed slice contract is the
-	// same as Commit. Implementations that don't coalesce may delegate to
-	// Commit.
-	CommitInbound(pkt []byte, parsed *RxParsed) error
-	// Flush emits every queued packet in arrival order. Returns the
-	// first error observed; keeps draining so one bad packet doesn't hold up
-	// the rest. After Flush returns, borrowed payload slices may be recycled.
-	Flush() error
-}
-
-type TxBatcher interface {
-	// Reserve creates a pkt to borrow
-	Reserve(sz int) []byte
-	// Commit borrows pkt and records its destination plus the 2-bit
-	// IP-level ECN codepoint to set on the outer (carrier) header. The
-	// caller must keep pkt valid until the next Flush. Pass 0 (Not-ECT)
-	// to leave the outer ECN field unset.
-	Commit(pkt []byte, dst netip.AddrPort, outerECN byte)
-	// Flush emits every queued packet via the underlying batch writer in
-	// arrival order. Returns an errors.Join of one or more errors. After Flush returns,
-	// borrowed payload slices may be recycled.
-	Flush() error
-}

overlay/batch/coalesce_core.go

@@ -1,163 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"encoding/binary"
-)
-
-// flowKey identifies a transport flow by {src, dst, sport, dport, family}.
-// Comparable, so map lookups and linear scans over the slot list stay tight.
-// Shared by the TCP and UDP coalescers; each coalescer keeps its own
-// openSlots map, so a TCP and UDP flow on the same 5-tuple-without-proto
-// never alias.
-type flowKey struct {
-	src, dst     [16]byte
-	sport, dport uint16
-	isV6         bool
-}
-
-// initialSlots is the starting capacity of the slot pool. One flow per
-// packet is the worst case so this matches a typical carrier-side
-// recvmmsg batch on the encrypted UDP socket.
-const initialSlots = 64
-
-// parsedIP is the IP-level result of parseIPPrologue. The caller layers
-// L4-specific parsing (TCP / UDP) on top.
-type parsedIP struct {
-	fk       flowKey
-	ipHdrLen int
-	// pkt is the original buffer trimmed to the IP-declared total length.
-	// Anything below the IP layer (transport parsers) should slice into
-	// pkt rather than the unbounded original.
-	pkt []byte
-}
-
-// parseIPPrologue extracts the IP-level fields the coalescers care about:
-// IHL/payload length, version, src/dst addresses, and the L4 protocol byte.
-// Returns ok=false for malformed input, IPv4 with options or fragmentation,
-// or IPv6 with extension headers (all rejected by both coalescers in
-// identical ways before this refactor).
-//
-// On success, p.pkt is len-trimmed to the IP-declared length so callers
-// don't have to repeat the trim. wantProto is the IANA protocol number to
-// require (6 for TCP, 17 for UDP); ok=false for any other value.
-func parseIPPrologue(pkt []byte, wantProto byte) (parsedIP, bool) {
-	var p parsedIP
-	if len(pkt) < 20 {
-		return p, false
-	}
-	v := pkt[0] >> 4
-	switch v {
-	case 4:
-		ihl := int(pkt[0]&0x0f) * 4
-		if ihl != 20 {
-			return p, false
-		}
-		if pkt[9] != wantProto {
-			return p, false
-		}
-		// Reject actual fragmentation (MF or non-zero frag offset).
-		if binary.BigEndian.Uint16(pkt[6:8])&0x3fff != 0 {
-			return p, false
-		}
-		totalLen := int(binary.BigEndian.Uint16(pkt[2:4]))
-		if totalLen > len(pkt) || totalLen < ihl {
-			return p, false
-		}
-		p.ipHdrLen = 20
-		p.fk.isV6 = false
-		copy(p.fk.src[:4], pkt[12:16])
-		copy(p.fk.dst[:4], pkt[16:20])
-		p.pkt = pkt[:totalLen]
-	case 6:
-		if len(pkt) < 40 {
-			return p, false
-		}
-		if pkt[6] != wantProto {
-			return p, false
-		}
-		payloadLen := int(binary.BigEndian.Uint16(pkt[4:6]))
-		if 40+payloadLen > len(pkt) {
-			return p, false
-		}
-		p.ipHdrLen = 40
-		p.fk.isV6 = true
-		copy(p.fk.src[:], pkt[8:24])
-		copy(p.fk.dst[:], pkt[24:40])
-		p.pkt = pkt[:40+payloadLen]
-	default:
-		return p, false
-	}
-	return p, true
-}
-
-// ipHeadersMatch compares the IP portion of two packet header prefixes for
-// byte-for-byte equality on every field that must be identical across
-// coalesced segments. Size/IPID/IPCsum and the 2-bit IP-level ECN field are
-// masked out — the appendPayload step merges CE into the seed.
-//
-// The transport (L4) portion of the header is checked separately by the
-// per-protocol matcher.
-func ipHeadersMatch(a, b []byte, isV6 bool) bool {
-	if isV6 {
-		// IPv6: byte 0 = version/TC[7:4], byte 1 = TC[3:0]/flow[19:16],
-		// bytes [2:4] = flow[15:0], [6:8] = next_hdr/hop, [8:40] = src+dst.
-		// ECN lives in TC[1:0] = byte 1 mask 0x30. Skip [4:6] payload_len.
-		if a[0] != b[0] {
-			return false
-		}
-		if a[1]&^0x30 != b[1]&^0x30 {
-			return false
-		}
-		if !bytes.Equal(a[2:4], b[2:4]) {
-			return false
-		}
-		if !bytes.Equal(a[6:40], b[6:40]) {
-			return false
-		}
-		return true
-	}
-	// IPv4: byte 0 = version/IHL, byte 1 = DSCP(6)|ECN(2),
-	// [6:10] flags/fragoff/TTL/proto, [12:20] src+dst.
-	// Skip [2:4] total len, [4:6] id, [10:12] csum.
-	if a[0] != b[0] {
-		return false
-	}
-	if a[1]&^0x03 != b[1]&^0x03 {
-		return false
-	}
-	if !bytes.Equal(a[6:10], b[6:10]) {
-		return false
-	}
-	if !bytes.Equal(a[12:20], b[12:20]) {
-		return false
-	}
-	return true
-}
-
-// mergeECNIntoSeed ORs the 2-bit IP-level ECN field of pkt's IP header
-// onto the seed's IP header, so a CE mark on any coalesced segment
-// propagates to the final superpacket. (CE is 0b11; ORing yields CE if
-// any segment carried it.) Used by both TCP and UDP coalescers, so the
-// invariant lives in one place.
-func mergeECNIntoSeed(seedHdr, pktHdr []byte, isV6 bool) {
-	if isV6 {
-		seedHdr[1] |= pktHdr[1] & 0x30
-	} else {
-		seedHdr[1] |= pktHdr[1] & 0x03
-	}
-}
-
-// reserveFromBacking implements the Reserve half of the RxBatcher contract
-// shared by TCP and UDP coalescers. The backing slice grows on demand;
-// already-committed slices reference the old array and remain valid until
-// Flush resets backing.
-func reserveFromBacking(backing *[]byte, sz int) []byte {
-	if len(*backing)+sz > cap(*backing) {
-		newCap := max(cap(*backing)*2, sz)
-		*backing = make([]byte, 0, newCap)
-	}
-	start := len(*backing)
-	*backing = (*backing)[:start+sz]
-	return (*backing)[start : start+sz : start+sz]
-}

overlay/batch/inbound.go

@@ -1,443 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"errors"
-
-	"github.com/slackhq/nebula/firewall"
-)
-
-// IANA protocol numbers we recognise during the inbound parse. Kept local
-// (rather than reaching for the firewall constants for every one of these)
-// so the byte-comparison hot path doesn't depend on cross-package values.
-const (
-	ipProtoICMP         = 1
-	ipProtoIPv6Fragment = 44
-	ipProtoESP          = 50
-	ipProtoAH           = 51
-	ipProtoICMPv6       = 58
-	ipProtoNoNextHdr    = 59
-
-	icmpv6TypeEchoRequest = 128
-	icmpv6TypeEchoReply   = 129
-)
-
-// Packet parse errors — the canonical sentinel set for IP+L4 parsing.
-// Both inbound and outbound callers share this surface, so any code path
-// that ends up at firewall.PacketKey reports drops with the same errors.
-var (
-	ErrPacketTooShort          = errors.New("packet is too short")
-	ErrUnknownIPVersion        = errors.New("packet is an unknown ip version")
-	ErrIPv4InvalidHeaderLength = errors.New("invalid ipv4 header length")
-	ErrIPv4PacketTooShort      = errors.New("ipv4 packet is too short")
-	ErrIPv6PacketTooShort      = errors.New("ipv6 packet is too short")
-	ErrIPv6CouldNotFindPayload = errors.New("could not find payload in ipv6 packet")
-)
-
-// RxKind discriminates how an inbound plaintext packet should be committed
-// after its firewall.Packet has been built. RxKindPassthrough means the
-// IP shape is valid (firewall could match on it) but the coalescer's
-// strict checks reject it — caller should still write it via the
-// passthrough lane.
-type RxKind uint8
-
-const (
-	RxKindPassthrough RxKind = iota
-	RxKindTCP
-	RxKindUDP
-)
-
-// RxParsed is the unified result of one IP+L4 walk:
-//   - Key: the firewall's conntrack/cache lookup key. The dense form lets
-//     firewall.Drop hit conntrack without ever filling the rich Packet's
-//     netip.Addr fields. On a conntrack miss, Drop hydrates the caller's
-//     Packet from Key.
-//   - tcp/udp: the coalescer hint so commitParsed doesn't re-walk the
-//     headers. Meaningful only when Kind is RxKindTCP / RxKindUDP.
-type RxParsed struct {
-	Kind RxKind
-	Key  firewall.PacketKey
-	tcp  parsedTCP
-	udp  parsedUDP
-}
-
-// ParsePacket walks an IP packet once and fills parsed.Key. When incoming
-// is true and the L4 shape is coalesce-eligible, also fills parsed.tcp /
-// parsed.udp so CommitInbound can dispatch into the coalescer without
-// re-walking the headers.
-//
-// Direction selects the Key orientation:
-//
-//	incoming=true  → wire src → Key.RemoteAddr/Port, wire dst → Key.LocalAddr/Port
-//	incoming=false → wire src → Key.LocalAddr/Port,  wire dst → Key.RemoteAddr/Port
-//
-// ICMP always lands the identifier in Key.RemotePort, regardless of direction.
-//
-// Eligibility rules for the coalescer hint match the coalescer's own
-// parseTCPBase/parseUDP:
-//   - IPv4 strict: IHL == 20, no fragmentation (MF or offset), proto TCP/UDP.
-//   - IPv6 strict: NextHeader is directly TCP or UDP (no extension headers).
-//
-// The hint is only filled for incoming packets, since the outbound path
-// does not feed an inbound coalescer. Outbound callers see Kind stay at
-// RxKindPassthrough and parsed.tcp/udp stay zero.
-func ParsePacket(pkt []byte, incoming bool, parsed *RxParsed) error {
-	parsed.Kind = RxKindPassthrough
-	// Reset Key in full: v4 only writes the low 4 bytes of each address
-	// field, so without this a v6 call followed by a v4 reusing the same
-	// RxParsed would inherit the high 12 bytes — breaking the conntrack
-	// map equality for v4 flows.
-	parsed.Key = firewall.PacketKey{}
-	if len(pkt) < 1 {
-		return ErrPacketTooShort
-	}
-	switch pkt[0] >> 4 {
-	case 4:
-		return parsePacketV4(pkt, incoming, parsed)
-	case 6:
-		return parsePacketV6(pkt, incoming, parsed)
-	}
-	return ErrUnknownIPVersion
-}
-
-// parsePacketV4 fills parsed.Key from an IPv4 packet. Direction selects
-// Local/Remote orientation. When incoming and the shape is strict, also
-// fills the coalescer hint.
-func parsePacketV4(pkt []byte, incoming bool, parsed *RxParsed) error {
-	if len(pkt) < 20 {
-		return ErrIPv4PacketTooShort
-	}
-	ihl := int(pkt[0]&0x0f) << 2
-	if ihl < 20 {
-		return ErrIPv4InvalidHeaderLength
-	}
-	flagsfrags := binary.BigEndian.Uint16(pkt[6:8])
-	parsed.Key.Fragment = (flagsfrags & 0x1FFF) != 0
-	parsed.Key.Protocol = pkt[9]
-	parsed.Key.IsV6 = false
-
-	// minFwPacketLen (4) is the L4-header prefix the firewall needs to pull
-	// ports; ICMP needs two extra bytes for the identifier.
-	minLen := ihl
-	if !parsed.Key.Fragment {
-		if parsed.Key.Protocol == firewall.ProtoICMP {
-			minLen += 4 + 2
-		} else {
-			minLen += 4
-		}
-	}
-	if len(pkt) < minLen {
-		return ErrIPv4InvalidHeaderLength
-	}
-
-	if incoming {
-		copy(parsed.Key.RemoteAddr[:4], pkt[12:16])
-		copy(parsed.Key.LocalAddr[:4], pkt[16:20])
-	} else {
-		copy(parsed.Key.LocalAddr[:4], pkt[12:16])
-		copy(parsed.Key.RemoteAddr[:4], pkt[16:20])
-	}
-
-	switch {
-	case parsed.Key.Fragment:
-		parsed.Key.RemotePort = 0
-		parsed.Key.LocalPort = 0
-	case parsed.Key.Protocol == firewall.ProtoICMP:
-		parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[ihl+4 : ihl+6])
-		parsed.Key.LocalPort = 0
-	case incoming:
-		parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[ihl : ihl+2])
-		parsed.Key.LocalPort = binary.BigEndian.Uint16(pkt[ihl+2 : ihl+4])
-	default:
-		parsed.Key.LocalPort = binary.BigEndian.Uint16(pkt[ihl : ihl+2])
-		parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[ihl+2 : ihl+4])
-	}
-
-	// Coalescer hint is inbound-only: no inbound coalescer fires on outgoing.
-	if !incoming {
-		return nil
-	}
-	// Coalescer-eligible? Strict shape: IHL==20, no MF/offset, TCP or UDP.
-	if ihl != 20 || (flagsfrags&0x3FFF) != 0 {
-		return nil
-	}
-	if parsed.Key.Protocol != ipProtoTCP && parsed.Key.Protocol != ipProtoUDP {
-		return nil
-	}
-	totalLen := int(binary.BigEndian.Uint16(pkt[2:4]))
-	if totalLen > len(pkt) || totalLen < 20 {
-		return nil
-	}
-	pktTrim := pkt[:totalLen]
-
-	switch parsed.Key.Protocol {
-	case ipProtoTCP:
-		fillParsedTCPv4(pktTrim, parsed)
-	case ipProtoUDP:
-		fillParsedUDPv4(pktTrim, parsed)
-	}
-	return nil
-}
-
-// fillParsedTCPv4 fills parsed.tcp from a strict-shape IPv4+TCP packet
-// already validated to have IHL==20 and to be totalLen-trimmed.
-func fillParsedTCPv4(pkt []byte, parsed *RxParsed) {
-	if len(pkt) < 40 { // IPv4(20) + min TCP(20)
-		return
-	}
-	tcpOff := int(pkt[32]>>4) * 4
-	if tcpOff < 20 || tcpOff > 60 {
-		return
-	}
-	if len(pkt) < 20+tcpOff {
-		return
-	}
-	p := &parsed.tcp
-	p.ipHdrLen = 20
-	p.tcpHdrLen = tcpOff
-	p.hdrLen = 20 + tcpOff
-	p.payLen = len(pkt) - p.hdrLen
-	p.seq = binary.BigEndian.Uint32(pkt[24:28])
-	p.flags = pkt[33]
-	p.fk.isV6 = false
-	p.fk.sport = parsed.Key.RemotePort
-	p.fk.dport = parsed.Key.LocalPort
-	copy(p.fk.src[:4], pkt[12:16])
-	copy(p.fk.dst[:4], pkt[16:20])
-	parsed.Kind = RxKindTCP
-}
-
-// fillParsedUDPv4 fills parsed.udp from a strict-shape IPv4+UDP packet.
-func fillParsedUDPv4(pkt []byte, parsed *RxParsed) {
-	if len(pkt) < 28 { // IPv4(20) + UDP(8)
-		return
-	}
-	udpLen := int(binary.BigEndian.Uint16(pkt[24:26]))
-	if udpLen < 8 || udpLen > len(pkt)-20 {
-		return
-	}
-	p := &parsed.udp
-	p.ipHdrLen = 20
-	p.hdrLen = 28
-	p.payLen = udpLen - 8
-	p.fk.isV6 = false
-	p.fk.sport = parsed.Key.RemotePort
-	p.fk.dport = parsed.Key.LocalPort
-	copy(p.fk.src[:4], pkt[12:16])
-	copy(p.fk.dst[:4], pkt[16:20])
-	parsed.Kind = RxKindUDP
-}
-
-// parsePacketV6 fills parsed.Key from an IPv6 packet. Direction selects
-// Local/Remote orientation. The coalescer hint fast path only triggers
-// when NextHeader is directly TCP or UDP — any extension header chain
-// falls into the lenient walk below, and the hint stays unfilled.
-func parsePacketV6(pkt []byte, incoming bool, parsed *RxParsed) error {
-	if len(pkt) < 40 {
-		return ErrIPv6PacketTooShort
-	}
-	parsed.Key.IsV6 = true
-	if incoming {
-		copy(parsed.Key.RemoteAddr[:], pkt[8:24])
-		copy(parsed.Key.LocalAddr[:], pkt[24:40])
-	} else {
-		copy(parsed.Key.LocalAddr[:], pkt[8:24])
-		copy(parsed.Key.RemoteAddr[:], pkt[24:40])
-	}
-
-	if proto := pkt[6]; proto == ipProtoTCP || proto == ipProtoUDP {
-		// Strict v6: ports are at the IP header end. Always fill key; only
-		// fill the coalescer hint if the L4 shape passes.
-		if len(pkt) < 44 {
-			return ErrIPv6PacketTooShort
-		}
-		parsed.Key.Protocol = proto
-		parsed.Key.Fragment = false
-		if incoming {
-			parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[40:42])
-			parsed.Key.LocalPort = binary.BigEndian.Uint16(pkt[42:44])
-		} else {
-			parsed.Key.LocalPort = binary.BigEndian.Uint16(pkt[40:42])
-			parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[42:44])
-		}
-
-		// Coalescer hint is inbound-only.
-		if !incoming {
-			return nil
-		}
-		payloadLen := int(binary.BigEndian.Uint16(pkt[4:6]))
-		if 40+payloadLen > len(pkt) {
-			return nil
-		}
-		pktTrim := pkt[:40+payloadLen]
-
-		switch proto {
-		case ipProtoTCP:
-			fillParsedTCPv6(pktTrim, parsed)
-		case ipProtoUDP:
-			fillParsedUDPv6(pktTrim, parsed)
-		}
-		return nil
-	}
-
-	// Slow path: walk extension header chain. Coalescer hint never fires
-	// here, so direction only matters for L4 port orientation.
-	return walkV6Headers(pkt, incoming, parsed)
-}
-
-func fillParsedTCPv6(pkt []byte, parsed *RxParsed) {
-	if len(pkt) < 60 { // IPv6(40) + min TCP(20)
-		return
-	}
-	tcpOff := int(pkt[52]>>4) * 4
-	if tcpOff < 20 || tcpOff > 60 {
-		return
-	}
-	if len(pkt) < 40+tcpOff {
-		return
-	}
-	p := &parsed.tcp
-	p.ipHdrLen = 40
-	p.tcpHdrLen = tcpOff
-	p.hdrLen = 40 + tcpOff
-	p.payLen = len(pkt) - p.hdrLen
-	p.seq = binary.BigEndian.Uint32(pkt[44:48])
-	p.flags = pkt[53]
-	p.fk.isV6 = true
-	p.fk.sport = parsed.Key.RemotePort
-	p.fk.dport = parsed.Key.LocalPort
-	copy(p.fk.src[:], pkt[8:24])
-	copy(p.fk.dst[:], pkt[24:40])
-	parsed.Kind = RxKindTCP
-}
-
-func fillParsedUDPv6(pkt []byte, parsed *RxParsed) {
-	if len(pkt) < 48 { // IPv6(40) + UDP(8)
-		return
-	}
-	udpLen := int(binary.BigEndian.Uint16(pkt[44:46]))
-	if udpLen < 8 || udpLen > len(pkt)-40 {
-		return
-	}
-	p := &parsed.udp
-	p.ipHdrLen = 40
-	p.hdrLen = 48
-	p.payLen = udpLen - 8
-	p.fk.isV6 = true
-	p.fk.sport = parsed.Key.RemotePort
-	p.fk.dport = parsed.Key.LocalPort
-	copy(p.fk.src[:], pkt[8:24])
-	copy(p.fk.dst[:], pkt[24:40])
-	parsed.Kind = RxKindUDP
-}
-
-// walkV6Headers handles every IPv6 case the strict "NextHeader == TCP/UDP"
-// fast path doesn't: ESP, NoNextHeader, ICMPv6, fragment headers (first vs
-// later), AH, generic extension headers. Coalescer eligibility is always
-// RxKindPassthrough on this path (parsed already initialised that way).
-// Direction matters only for the L4 port orientation when the chain
-// terminates at TCP/UDP.
-func walkV6Headers(pkt []byte, incoming bool, parsed *RxParsed) error {
-	dataLen := len(pkt)
-	protoAt := 6
-	offset := 40
-	next := 0
-	for {
-		if protoAt >= dataLen {
-			break
-		}
-		proto := pkt[protoAt]
-		switch proto {
-		case ipProtoESP, ipProtoNoNextHdr:
-			parsed.Key.Protocol = proto
-			parsed.Key.RemotePort = 0
-			parsed.Key.LocalPort = 0
-			parsed.Key.Fragment = false
-			return nil
-
-		case ipProtoICMPv6:
-			if dataLen < offset+6 {
-				return ErrIPv6PacketTooShort
-			}
-			parsed.Key.Protocol = proto
-			parsed.Key.LocalPort = 0
-			switch pkt[offset+1] {
-			case icmpv6TypeEchoRequest, icmpv6TypeEchoReply:
-				parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[offset+4 : offset+6])
-			default:
-				parsed.Key.RemotePort = 0
-			}
-			parsed.Key.Fragment = false
-			return nil
-
-		case ipProtoTCP, ipProtoUDP:
-			// Reachable when an extension-header chain ends at TCP/UDP. The
-			// strict-eligible fast path above already handled the no-extension
-			// case; here we only fill firewall ports and stay passthrough.
-			if dataLen < offset+4 {
-				return ErrIPv6PacketTooShort
-			}
-			parsed.Key.Protocol = proto
-			if incoming {
-				parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[offset : offset+2])
-				parsed.Key.LocalPort = binary.BigEndian.Uint16(pkt[offset+2 : offset+4])
-			} else {
-				parsed.Key.LocalPort = binary.BigEndian.Uint16(pkt[offset : offset+2])
-				parsed.Key.RemotePort = binary.BigEndian.Uint16(pkt[offset+2 : offset+4])
-			}
-			parsed.Key.Fragment = false
-			return nil
-
-		case ipProtoIPv6Fragment:
-			if dataLen < offset+8 {
-				return ErrIPv6PacketTooShort
-			}
-			fragmentOffset := binary.BigEndian.Uint16(pkt[offset+2:offset+4]) &^ uint16(0x7)
-			if fragmentOffset != 0 {
-				// Non-first fragment: report the fragment flag and stop.
-				parsed.Key.Protocol = pkt[offset]
-				parsed.Key.Fragment = true
-				parsed.Key.RemotePort = 0
-				parsed.Key.LocalPort = 0
-				return nil
-			}
-			next = 8
-
-		case ipProtoAH:
-			if dataLen <= offset+1 {
-				break
-			}
-			next = int(pkt[offset+1]+2) << 2
-
-		default:
-			if dataLen <= offset+1 {
-				break
-			}
-			next = int(pkt[offset+1]+1) << 3
-		}
-
-		if next <= 0 {
-			next = 8
-		}
-		protoAt = offset
-		offset = offset + next
-	}
-	return ErrIPv6CouldNotFindPayload
-}
-
-// CommitInbound dispatches pkt to the appropriate lane using parsed.Kind,
-// skipping the IP+L4 re-parse that MultiCoalescer.Commit would otherwise
-// do. Borrowed slice contract is identical to MultiCoalescer.Commit.
-func (m *MultiCoalescer) CommitInbound(pkt []byte, parsed *RxParsed) error {
-	switch parsed.Kind {
-	case RxKindTCP:
-		if m.tcp != nil {
-			return m.tcp.commitParsed(pkt, parsed.tcp)
-		}
-	case RxKindUDP:
-		if m.udp != nil {
-			return m.udp.commitParsed(pkt, parsed.udp)
-		}
-	}
-	return m.pt.Commit(pkt)
-}

overlay/batch/inbound_bench_test.go

@@ -1,394 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"net/netip"
-	"testing"
-
-	"github.com/slackhq/nebula/firewall"
-)
-
-// parseV4InboundBaseline mirrors what outside.go's parseV4(incoming=true)
-// does, so the "split" bench measures the *current* state: firewall-side
-// parse, then m.Commit re-parses inside the coalescer. Two walks per
-// packet. Kept faithful in shape (one read per field, AddrFromSlice for
-// the addrs) so the CPU profile matches the production parseV4.
-func parseV4InboundBaseline(pkt []byte, fp *firewall.Packet) bool {
-	if len(pkt) < 20 {
-		return false
-	}
-	ihl := int(pkt[0]&0x0f) << 2
-	if ihl < 20 {
-		return false
-	}
-	flagsfrags := binary.BigEndian.Uint16(pkt[6:8])
-	fp.Fragment = (flagsfrags & 0x1FFF) != 0
-	fp.Protocol = pkt[9]
-	minLen := ihl
-	if !fp.Fragment {
-		if fp.Protocol == firewall.ProtoICMP {
-			minLen += 4 + 2
-		} else {
-			minLen += 4
-		}
-	}
-	if len(pkt) < minLen {
-		return false
-	}
-	fp.RemoteAddr, _ = netip.AddrFromSlice(pkt[12:16])
-	fp.LocalAddr, _ = netip.AddrFromSlice(pkt[16:20])
-	switch {
-	case fp.Fragment:
-		fp.RemotePort = 0
-		fp.LocalPort = 0
-	case fp.Protocol == firewall.ProtoICMP:
-		fp.RemotePort = binary.BigEndian.Uint16(pkt[ihl+4 : ihl+6])
-		fp.LocalPort = 0
-	default:
-		fp.RemotePort = binary.BigEndian.Uint16(pkt[ihl : ihl+2])
-		fp.LocalPort = binary.BigEndian.Uint16(pkt[ihl+2 : ihl+4])
-	}
-	return true
-}
-
-// parseV6InboundBaseline is the v6 analogue: replicates parseV6's
-// extension-header walk so the split bench captures its true cost.
-func parseV6InboundBaseline(pkt []byte, fp *firewall.Packet) bool {
-	dataLen := len(pkt)
-	if dataLen < 40 {
-		return false
-	}
-	fp.RemoteAddr, _ = netip.AddrFromSlice(pkt[8:24])
-	fp.LocalAddr, _ = netip.AddrFromSlice(pkt[24:40])
-
-	protoAt := 6
-	offset := 40
-	next := 0
-	for {
-		if protoAt >= dataLen {
-			return false
-		}
-		proto := pkt[protoAt]
-		switch proto {
-		case ipProtoESP, ipProtoNoNextHdr:
-			fp.Protocol = proto
-			fp.RemotePort = 0
-			fp.LocalPort = 0
-			fp.Fragment = false
-			return true
-		case ipProtoICMPv6:
-			if dataLen < offset+6 {
-				return false
-			}
-			fp.Protocol = proto
-			fp.LocalPort = 0
-			switch pkt[offset+1] {
-			case icmpv6TypeEchoRequest, icmpv6TypeEchoReply:
-				fp.RemotePort = binary.BigEndian.Uint16(pkt[offset+4 : offset+6])
-			default:
-				fp.RemotePort = 0
-			}
-			fp.Fragment = false
-			return true
-		case ipProtoTCP, ipProtoUDP:
-			if dataLen < offset+4 {
-				return false
-			}
-			fp.Protocol = proto
-			fp.RemotePort = binary.BigEndian.Uint16(pkt[offset : offset+2])
-			fp.LocalPort = binary.BigEndian.Uint16(pkt[offset+2 : offset+4])
-			fp.Fragment = false
-			return true
-		case ipProtoIPv6Fragment:
-			if dataLen < offset+8 {
-				return false
-			}
-			fragmentOffset := binary.BigEndian.Uint16(pkt[offset+2:offset+4]) &^ uint16(0x7)
-			if fragmentOffset != 0 {
-				fp.Protocol = pkt[offset]
-				fp.Fragment = true
-				fp.RemotePort = 0
-				fp.LocalPort = 0
-				return true
-			}
-			next = 8
-		case ipProtoAH:
-			if dataLen <= offset+1 {
-				return false
-			}
-			next = int(pkt[offset+1]+2) << 2
-		default:
-			if dataLen <= offset+1 {
-				return false
-			}
-			next = int(pkt[offset+1]+1) << 3
-		}
-		if next <= 0 {
-			next = 8
-		}
-		protoAt = offset
-		offset = offset + next
-	}
-}
-
-// runRxSplit drives the split path: faithful inbound parse for the firewall
-// side, then m.Commit re-parses to coalesce. v6 controls which baseline
-// parser we run.
-func runRxSplit(b *testing.B, pkts [][]byte, batchSize int, v6 bool) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, true, true)
-	var fp firewall.Packet
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		pkt := pkts[i%len(pkts)]
-		var ok bool
-		if v6 {
-			ok = parseV6InboundBaseline(pkt, &fp)
-		} else {
-			ok = parseV4InboundBaseline(pkt, &fp)
-		}
-		if !ok {
-			b.Fatal("baseline parse failed")
-		}
-		if err := m.Commit(pkt); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			if err := m.Flush(); err != nil {
-				b.Fatal(err)
-			}
-		}
-	}
-	_ = m.Flush()
-}
-
-// runRxUnified drives the unified path: ParseInbound walks once, filling
-// the conntrack key + coalescer hint in parsed; CommitInbound dispatches
-// without re-parsing.
-func runRxUnified(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, true, true)
-	var parsed RxParsed
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		pkt := pkts[i%len(pkts)]
-		if err := ParsePacket(pkt, true, &parsed); err != nil {
-			b.Fatal(err)
-		}
-		if err := m.CommitInbound(pkt, &parsed); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			if err := m.Flush(); err != nil {
-				b.Fatal(err)
-			}
-		}
-	}
-	_ = m.Flush()
-}
-
-// buildUDPv4Bulk returns N UDP packets on a single 5-tuple suitable for the
-// UDP coalescer's append path.
-func buildUDPv4Bulk(n, payloadLen int) [][]byte {
-	pkts := make([][]byte, n)
-	pay := make([]byte, payloadLen)
-	for i := range n {
-		pkts[i] = buildUDPv4(1000, 53, pay)
-	}
-	return pkts
-}
-
-func buildTCPv6Bulk(n, payloadLen int) [][]byte {
-	pkts := make([][]byte, n)
-	pay := make([]byte, payloadLen)
-	seq := uint32(1000)
-	for i := range n {
-		pkts[i] = buildTCPv6(0, seq, tcpAck, pay)
-		seq += uint32(payloadLen)
-	}
-	return pkts
-}
-
-func buildICMPv4Bulk(n int) [][]byte {
-	pkts := make([][]byte, n)
-	for i := range pkts {
-		pkts[i] = buildICMPv4()
-	}
-	return pkts
-}
-
-// === TCPv4 ===
-
-func BenchmarkRxSplitTCPv4(b *testing.B) {
-	pkts := buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200)
-	runRxSplit(b, pkts, tcpCoalesceMaxSegs, false)
-}
-
-func BenchmarkRxUnifiedTCPv4(b *testing.B) {
-	pkts := buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200)
-	runRxUnified(b, pkts, tcpCoalesceMaxSegs)
-}
-
-// === TCPv4 interleaved (4 flows) ===
-
-func BenchmarkRxSplitTCPv4Interleaved4(b *testing.B) {
-	pkts := buildTCPv4Interleaved(4, tcpCoalesceMaxSegs, 1200)
-	runRxSplit(b, pkts, len(pkts), false)
-}
-
-func BenchmarkRxUnifiedTCPv4Interleaved4(b *testing.B) {
-	pkts := buildTCPv4Interleaved(4, tcpCoalesceMaxSegs, 1200)
-	runRxUnified(b, pkts, len(pkts))
-}
-
-// === UDPv4 ===
-
-func BenchmarkRxSplitUDPv4(b *testing.B) {
-	pkts := buildUDPv4Bulk(udpCoalesceMaxSegs, 1200)
-	runRxSplit(b, pkts, udpCoalesceMaxSegs, false)
-}
-
-func BenchmarkRxUnifiedUDPv4(b *testing.B) {
-	pkts := buildUDPv4Bulk(udpCoalesceMaxSegs, 1200)
-	runRxUnified(b, pkts, udpCoalesceMaxSegs)
-}
-
-// === TCPv6 ===
-
-func BenchmarkRxSplitTCPv6(b *testing.B) {
-	pkts := buildTCPv6Bulk(tcpCoalesceMaxSegs, 1200)
-	runRxSplit(b, pkts, tcpCoalesceMaxSegs, true)
-}
-
-func BenchmarkRxUnifiedTCPv6(b *testing.B) {
-	pkts := buildTCPv6Bulk(tcpCoalesceMaxSegs, 1200)
-	runRxUnified(b, pkts, tcpCoalesceMaxSegs)
-}
-
-// === ICMPv4 (passthrough) — measures the unified parser on the coalescer-
-// rejected path, where both lenient and unified must still fill fp. ===
-
-func BenchmarkRxSplitICMPv4(b *testing.B) {
-	pkts := buildICMPv4Bulk(64)
-	runRxSplit(b, pkts, 64, false)
-}
-
-func BenchmarkRxUnifiedICMPv4(b *testing.B) {
-	pkts := buildICMPv4Bulk(64)
-	runRxUnified(b, pkts, 64)
-}
-
-// === Firewall fast-path (conntrack-hit) — exercises the savings from the
-// dense PacketKey: smaller hash key for the per-routine ConntrackCache,
-// and skipping the AddrFrom4 calls that the old path needed to fill the
-// netip.Addr-rich firewall.Packet up-front. ===
-//
-// The "split" baseline simulates the legacy path: parseV4InboundBaseline
-// fills a netip.Addr-rich Packet, then we probe a localCache keyed on
-// Packet. The "unified" path: ParseInbound fills only the dense PacketKey,
-// and we probe a localCache keyed on PacketKey. Both paths follow with
-// the coalescer Commit so the bench captures end-to-end RX-side cost.
-
-// runRxSplitWithCache mirrors runRxSplit but runs the legacy-style
-// firewall fast path (localCache keyed on firewall.Packet) on every
-// packet so we can compare against the unified path.
-func runRxSplitWithCache(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, true, true)
-	var fp firewall.Packet
-
-	// Pre-warm a per-packet cache keyed on the netip.Addr-rich Packet form.
-	cache := make(map[firewall.Packet]struct{}, len(pkts))
-	for _, pkt := range pkts {
-		var seedFp firewall.Packet
-		if !parseV4InboundBaseline(pkt, &seedFp) {
-			b.Fatal("seed parse failed")
-		}
-		cache[seedFp] = struct{}{}
-	}
-
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		pkt := pkts[i%len(pkts)]
-		if !parseV4InboundBaseline(pkt, &fp) {
-			b.Fatal("baseline parse failed")
-		}
-		if _, ok := cache[fp]; !ok {
-			b.Fatal("cache miss")
-		}
-		if err := m.Commit(pkt); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			if err := m.Flush(); err != nil {
-				b.Fatal(err)
-			}
-		}
-	}
-	_ = m.Flush()
-}
-
-// runRxUnifiedWithCache: unified path with a PacketKey-keyed localCache.
-// Each iteration: ParseInbound → conntrack-cache hit → CommitInbound.
-func runRxUnifiedWithCache(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, true, true)
-	var parsed RxParsed
-
-	cache := make(firewall.ConntrackCache, len(pkts))
-	for _, pkt := range pkts {
-		var seed RxParsed
-		if err := ParsePacket(pkt, true, &seed); err != nil {
-			b.Fatal(err)
-		}
-		cache[seed.Key] = struct{}{}
-	}
-
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		pkt := pkts[i%len(pkts)]
-		if err := ParsePacket(pkt, true, &parsed); err != nil {
-			b.Fatal(err)
-		}
-		if _, ok := cache[parsed.Key]; !ok {
-			b.Fatal("cache miss")
-		}
-		if err := m.CommitInbound(pkt, &parsed); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			if err := m.Flush(); err != nil {
-				b.Fatal(err)
-			}
-		}
-	}
-	_ = m.Flush()
-}
-
-func BenchmarkRxSplitTCPv4WithCache(b *testing.B) {
-	pkts := buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200)
-	runRxSplitWithCache(b, pkts, tcpCoalesceMaxSegs)
-}
-
-func BenchmarkRxUnifiedTCPv4WithCache(b *testing.B) {
-	pkts := buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200)
-	runRxUnifiedWithCache(b, pkts, tcpCoalesceMaxSegs)
-}
-
-func BenchmarkRxSplitInterleaved4WithCache(b *testing.B) {
-	pkts := buildTCPv4Interleaved(4, tcpCoalesceMaxSegs, 1200)
-	runRxSplitWithCache(b, pkts, len(pkts))
-}
-
-func BenchmarkRxUnifiedInterleaved4WithCache(b *testing.B) {
-	pkts := buildTCPv4Interleaved(4, tcpCoalesceMaxSegs, 1200)
-	runRxUnifiedWithCache(b, pkts, len(pkts))
-}

overlay/batch/inbound_test.go

@@ -1,174 +0,0 @@
-package batch
-
-import (
-	"net/netip"
-	"testing"
-
-	"github.com/slackhq/nebula/firewall"
-)
-
-// TestParseInboundParity asserts that ParseInbound + Key.Hydrate produces
-// the same firewall.Packet that the lenient baseline parsers (which
-// mirror outside.go's parseV4/parseV6 with incoming=true) produce for
-// every shape we care about. Catches drift between the unified
-// parse-then-hydrate flow and the production newPacket behavior so
-// swapping one for the other is observably safe.
-func TestParseInboundParity(t *testing.T) {
-	cases := []struct {
-		name string
-		pkt  []byte
-		v6   bool
-	}{
-		{"tcp_v4", buildTCPv4Ports(1234, 443, 1000, tcpAck, []byte("payload")), false},
-		{"tcp_v4_psh", buildTCPv4Ports(1234, 443, 2000, tcpAckPsh, make([]byte, 1200)), false},
-		{"udp_v4", buildUDPv4(40000, 53, []byte("dnsquery")), false},
-		{"icmp_v4", buildICMPv4(), false},
-		{"tcp_v6", buildTCPv6(0, 5000, tcpAck, make([]byte, 800)), true},
-		{"udp_v6", buildUDPv6(40001, 53, []byte("v6dns")), true},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			var fpUnified, fpBaseline firewall.Packet
-			var parsed RxParsed
-
-			if err := ParsePacket(tc.pkt, true, &parsed); err != nil {
-				t.Fatalf("ParsePacket: %v", err)
-			}
-			parsed.Key.Hydrate(&fpUnified)
-			var ok bool
-			if tc.v6 {
-				ok = parseV6InboundBaseline(tc.pkt, &fpBaseline)
-			} else {
-				ok = parseV4InboundBaseline(tc.pkt, &fpBaseline)
-			}
-			if !ok {
-				t.Fatalf("baseline parse failed")
-			}
-
-			if fpUnified != fpBaseline {
-				t.Errorf("firewall.Packet mismatch:\n  unified:  %+v\n  baseline: %+v", fpUnified, fpBaseline)
-			}
-		})
-	}
-}
-
-// TestParseInboundFlowKey checks that the coalescer hint the unified parser
-// produces matches what parseTCPBase/parseUDP would produce on the same
-// packet — same flowKey, ipHdrLen, payLen, etc. The hint is only valid
-// when Kind is RxKindTCP/RxKindUDP.
-func TestParseInboundFlowKey(t *testing.T) {
-	t.Run("tcp_v4", func(t *testing.T) {
-		pkt := buildTCPv4Ports(1234, 443, 5000, tcpAck, make([]byte, 800))
-		var parsed RxParsed
-		if err := ParsePacket(pkt, true, &parsed); err != nil {
-			t.Fatal(err)
-		}
-		if parsed.Kind != RxKindTCP {
-			t.Fatalf("kind=%v want TCP", parsed.Kind)
-		}
-		ref, ok := parseTCPBase(pkt)
-		if !ok {
-			t.Fatal("parseTCPBase failed")
-		}
-		if parsed.tcp != ref {
-			t.Errorf("parsedTCP mismatch:\n  unified: %+v\n  ref:     %+v", parsed.tcp, ref)
-		}
-	})
-
-	t.Run("udp_v4", func(t *testing.T) {
-		pkt := buildUDPv4(40000, 53, []byte("dnsquery"))
-		var parsed RxParsed
-		if err := ParsePacket(pkt, true, &parsed); err != nil {
-			t.Fatal(err)
-		}
-		if parsed.Kind != RxKindUDP {
-			t.Fatalf("kind=%v want UDP", parsed.Kind)
-		}
-		ref, ok := parseUDP(pkt)
-		if !ok {
-			t.Fatal("parseUDP failed")
-		}
-		if parsed.udp != ref {
-			t.Errorf("parsedUDP mismatch:\n  unified: %+v\n  ref:     %+v", parsed.udp, ref)
-		}
-	})
-
-	t.Run("tcp_v6", func(t *testing.T) {
-		pkt := buildTCPv6(0, 9000, tcpAck, make([]byte, 800))
-		var parsed RxParsed
-		if err := ParsePacket(pkt, true, &parsed); err != nil {
-			t.Fatal(err)
-		}
-		if parsed.Kind != RxKindTCP {
-			t.Fatalf("kind=%v want TCP", parsed.Kind)
-		}
-		ref, ok := parseTCPBase(pkt)
-		if !ok {
-			t.Fatal("parseTCPBase failed")
-		}
-		if parsed.tcp != ref {
-			t.Errorf("parsedTCP mismatch:\n  unified: %+v\n  ref:     %+v", parsed.tcp, ref)
-		}
-	})
-}
-
-// TestParseInboundICMPPassthrough confirms ICMP packets populate the
-// conntrack key (including the ICMP identifier in RemotePort) but stay
-// RxKindPassthrough so the batcher writes them verbatim. After Hydrate
-// the firewall.Packet form should match what the legacy parseV4 produced.
-func TestParseInboundICMPPassthrough(t *testing.T) {
-	pkt := buildICMPv4()
-	// Stamp a non-zero identifier into the ICMP header so we can check
-	// RemotePort gets it.
-	pkt[20] = 8 // type=echo
-	pkt[24] = 0xab
-	pkt[25] = 0xcd
-
-	var parsed RxParsed
-	if err := ParsePacket(pkt, true, &parsed); err != nil {
-		t.Fatal(err)
-	}
-	if parsed.Kind != RxKindPassthrough {
-		t.Errorf("kind=%v want Passthrough", parsed.Kind)
-	}
-	var fp firewall.Packet
-	parsed.Key.Hydrate(&fp)
-	if fp.Protocol != firewall.ProtoICMP {
-		t.Errorf("Protocol=%d want %d", fp.Protocol, firewall.ProtoICMP)
-	}
-	if fp.RemotePort != 0xabcd {
-		t.Errorf("RemotePort=0x%x want 0xabcd", fp.RemotePort)
-	}
-	if fp.LocalPort != 0 {
-		t.Errorf("LocalPort=%d want 0", fp.LocalPort)
-	}
-	wantRemote := netip.MustParseAddr("10.0.0.1")
-	wantLocal := netip.MustParseAddr("10.0.0.2")
-	if fp.RemoteAddr != wantRemote || fp.LocalAddr != wantLocal {
-		t.Errorf("addrs: remote=%v local=%v want %v/%v", fp.RemoteAddr, fp.LocalAddr, wantRemote, wantLocal)
-	}
-}
-
-// TestParseInboundV4Fragment confirms a fragmented v4 packet fills the
-// conntrack key with Fragment=true and falls into Passthrough on the
-// coalescer side.
-func TestParseInboundV4Fragment(t *testing.T) {
-	// Build a TCP packet then twiddle the IP flags to make it look like a
-	// non-first fragment (offset != 0).
-	pkt := buildTCPv4Ports(1234, 443, 1000, tcpAck, []byte("payload"))
-	// Set a non-zero fragment offset (bytes 6-7, low 13 bits).
-	pkt[6] = 0x00
-	pkt[7] = 0x10 // offset = 16 (in 8-byte units)
-
-	var parsed RxParsed
-	if err := ParsePacket(pkt, true, &parsed); err != nil {
-		t.Fatal(err)
-	}
-	if !parsed.Key.Fragment {
-		t.Error("Fragment=false, want true")
-	}
-	if parsed.Kind != RxKindPassthrough {
-		t.Errorf("kind=%v want Passthrough", parsed.Kind)
-	}
-}

overlay/batch/multi_coalesce.go

@@ -1,133 +0,0 @@
-package batch
-
-import (
-	"errors"
-	"io"
-)
-
-// MultiCoalescer fans plaintext packets out to lane-specific batchers based
-// on the IP/L4 protocol of the packet, sharing a single Reserve arena
-// across lanes so the caller's allocation pattern is unchanged.
-//
-// Lanes are processed independently: the TCP coalescer only sees TCP, the
-// UDP coalescer only sees UDP, and the passthrough lane handles everything
-// else. Per-flow arrival order is preserved because a single 5-tuple only
-// ever lands in one lane and each lane preserves its own slot order.
-//
-// Cross-lane order is NOT preserved across the TCP/UDP/passthrough split.
-// This is acceptable because the carrier-side recvmmsg path already
-// stable-sorts by (peer, message counter) before delivering plaintext
-// here, so replay-window invariants are unaffected, and apps observe
-// correct per-flow ordering — which is all the IP layer guarantees anyway.
-// Do not "fix" this by interleaving lane outputs at flush time; that
-// negates the entire point of coalescing (each lane needs to see runs of
-// adjacent same-flow packets to coalesce them).
-type MultiCoalescer struct {
-	tcp *TCPCoalescer
-	udp *UDPCoalescer
-	pt  *Passthrough
-
-	// arena shared across all lanes so a single Reserve grows one backing
-	// slice; lane Commit calls borrow into this same arena.
-	backing []byte
-}
-
-// NewMultiCoalescer builds a multi-lane batcher. tcpEnabled lets the caller
-// opt out of TCP coalescing (e.g. when the queue can't do TSO); udpEnabled
-// likewise gates UDP coalescing (only enable when USO was negotiated).
-// Either lane disabled redirects its traffic into the passthrough lane.
-func NewMultiCoalescer(w io.Writer, tcpEnabled, udpEnabled bool) *MultiCoalescer {
-	m := &MultiCoalescer{
-		pt:      NewPassthrough(w),
-		backing: make([]byte, 0, initialSlots*65535),
-	}
-	if tcpEnabled {
-		m.tcp = NewTCPCoalescer(w)
-	}
-	if udpEnabled {
-		m.udp = NewUDPCoalescer(w)
-	}
-	return m
-}
-
-func (m *MultiCoalescer) Reserve(sz int) []byte {
-	if len(m.backing)+sz > cap(m.backing) {
-		newCap := max(cap(m.backing)*2, sz)
-		m.backing = make([]byte, 0, newCap)
-	}
-	start := len(m.backing)
-	m.backing = m.backing[:start+sz]
-	return m.backing[start : start+sz : start+sz]
-}
-
-// Commit dispatches pkt to the appropriate lane based on IP version + L4
-// proto. Borrowed slice contract is identical to the single-lane batchers,
-// pkt must remain valid until the next Flush.
-//
-// On the success path the IP/TCP-or-UDP parse happens here once and the
-// parsed struct is handed to the lane via commitParsed so the lane doesn't
-// re-walk the header.
-func (m *MultiCoalescer) Commit(pkt []byte) error {
-	if len(pkt) < 20 {
-		return m.pt.Commit(pkt)
-	}
-	v := pkt[0] >> 4
-	var proto byte
-	switch v {
-	case 4:
-		proto = pkt[9]
-	case 6:
-		if len(pkt) < 40 {
-			return m.pt.Commit(pkt)
-		}
-		proto = pkt[6]
-	default:
-		return m.pt.Commit(pkt)
-	}
-	switch proto {
-	case ipProtoTCP:
-		if m.tcp != nil {
-			info, ok := parseTCPBase(pkt)
-			if !ok {
-				// Malformed/unsupported TCP shape (IP options, fragments, ...).
-				// Handle this via passthrough support in the TCP coalescer, to attempt to preserve flow order.
-				m.tcp.addPassthrough(pkt)
-				return nil
-			}
-			return m.tcp.commitParsed(pkt, info)
-		}
-	case ipProtoUDP:
-		if m.udp != nil {
-			info, ok := parseUDP(pkt)
-			if !ok {
-				m.udp.addPassthrough(pkt) //we could also m.pt.Commit() here I guess?
-				return nil
-			}
-			return m.udp.commitParsed(pkt, info)
-		}
-	}
-	return m.pt.Commit(pkt)
-}
-
-// Flush drains every lane in a fixed order: TCP, UDP, passthrough. Errors
-// from a lane do not stop subsequent lanes from flushing, we keep
-// draining and return the first observed error so a single bad packet
-// doesn't strand the others.
-func (m *MultiCoalescer) Flush() error {
-	var errs []error
-	if m.tcp != nil {
-		if err := m.tcp.Flush(); err != nil {
-			errs = append(errs, err)
-		}
-	}
-	if m.udp != nil {
-		if err := m.udp.Flush(); err != nil {
-			errs = append(errs, err)
-		}
-	}
-	if err := m.pt.Flush(); err != nil {
-		errs = append(errs, err)
-	}
-	m.backing = m.backing[:0]
-	return errors.Join(errs...)
-}

overlay/batch/multi_coalesce_test.go

@@ -1,94 +0,0 @@
-package batch
-
-import (
-	"testing"
-)
-
-// TestMultiCoalescerRoutesByProto confirms TCP/UDP/other land in the right
-// lane: TCP and UDP get coalesced when their lanes are enabled, anything
-// else (ICMP here) falls through to plain Write.
-func TestMultiCoalescerRoutesByProto(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := NewMultiCoalescer(w, true, true)
-
-	tcpPay := make([]byte, 1200)
-	udpPay := make([]byte, 1200)
-	icmp := make([]byte, 28)
-	icmp[0] = 0x45
-	icmp[2] = 0
-	icmp[3] = 28
-	icmp[9] = 1
-
-	if err := m.Commit(buildTCPv4(1000, tcpAck, tcpPay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(2200, tcpAck, tcpPay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv4(2000, 53, udpPay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv4(2000, 53, udpPay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(icmp); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	// 1 TCP super (2 segments) + 1 UDP super (2 segments) = 2 gso writes.
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 gso writes (one TCP + one UDP), got %d", len(w.gsoWrites))
-	}
-	if len(w.writes) != 1 {
-		t.Fatalf("want 1 plain write (ICMP), got %d", len(w.writes))
-	}
-}
-
-// TestMultiCoalescerDisabledUDPFallsThrough verifies that when the UDP lane
-// is disabled (e.g. kernel doesn't support USO), UDP packets still reach
-// the kernel via the passthrough lane rather than being lost.
-func TestMultiCoalescerDisabledUDPFallsThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := NewMultiCoalescer(w, true, false) // TSO on, USO off
-
-	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 0 {
-		t.Errorf("UDP must NOT be coalesced when USO disabled, got %d gso writes", len(w.gsoWrites))
-	}
-	if len(w.writes) != 2 {
-		t.Errorf("UDP must pass through as 2 plain writes, got %d", len(w.writes))
-	}
-}
-
-// TestMultiCoalescerDisabledTCPFallsThrough mirrors the TSO=off case.
-func TestMultiCoalescerDisabledTCPFallsThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := NewMultiCoalescer(w, false, true) // TSO off, USO on
-
-	pay := make([]byte, 1200)
-	if err := m.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(2200, tcpAck, pay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 0 {
-		t.Errorf("TCP must NOT be coalesced when TSO disabled, got %d gso writes", len(w.gsoWrites))
-	}
-	if len(w.writes) != 2 {
-		t.Errorf("TCP must pass through as 2 plain writes, got %d", len(w.writes))
-	}
-}

overlay/batch/passthrough.go

@@ -1,62 +0,0 @@
-package batch
-
-import (
-	"io"
-
-	"github.com/slackhq/nebula/udp"
-)
-
-// Passthrough is a RxBatcher that doesn't batch anything, it just accumulates and then sends packets.
-type Passthrough struct {
-	out     io.Writer
-	slots   [][]byte
-	backing []byte
-	cursor  int
-}
-
-func NewPassthrough(w io.Writer) *Passthrough {
-	const baseNumSlots = 128
-	return &Passthrough{
-		out:     w,
-		slots:   make([][]byte, 0, baseNumSlots),
-		backing: make([]byte, 0, baseNumSlots*udp.MTU),
-	}
-}
-
-func (p *Passthrough) Reserve(sz int) []byte {
-	if len(p.backing)+sz > cap(p.backing) {
-		// Grow: allocate a fresh backing. Already-committed slices still
-		// reference the old array and remain valid until Flush drops them.
-		newCap := max(cap(p.backing)*2, sz)
-		p.backing = make([]byte, 0, newCap)
-	}
-	start := len(p.backing)
-	p.backing = p.backing[:start+sz]
-	return p.backing[start : start+sz : start+sz] //return zero length, sz-cap slice
-}
-
-func (p *Passthrough) Commit(pkt []byte) error {
-	p.slots = append(p.slots, pkt)
-	return nil
-}
-
-// CommitInbound ignores the hint — Passthrough never coalesces, so there's
-// no IP/L4 re-parse to skip. Present so Passthrough satisfies the RxBatcher
-// interface alongside MultiCoalescer.
-func (p *Passthrough) CommitInbound(pkt []byte, _ *RxParsed) error {
-	return p.Commit(pkt)
-}
-
-func (p *Passthrough) Flush() error {
-	var firstErr error
-	for _, s := range p.slots {
-		_, err := p.out.Write(s)
-		if err != nil && firstErr == nil {
-			firstErr = err
-		}
-	}
-	clear(p.slots)
-	p.slots = p.slots[:0]
-	p.backing = p.backing[:0]
-	return firstErr
-}

overlay/batch/tcp_coalesce.go

@@ -1,731 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"encoding/binary"
-	"io"
-	"log/slog"
-	"net/netip"
-	"slices"
-
-	"github.com/slackhq/nebula/overlay/tio"
-)
-
-// ipProtoTCP is the IANA protocol number for TCP. Hardcoded instead of
-// reaching for golang.org/x/sys/unix — that package doesn't define the
-// constant on Windows, which would break cross-compiles even though this
-// file runs unchanged on every platform.
-const ipProtoTCP = 6
-
-// tcpCoalesceBufSize caps total bytes per superpacket. Mirrors the kernel's
-// sk_gso_max_size of ~64KiB; anything beyond this would be rejected anyway.
-const tcpCoalesceBufSize = 65535
-
-// tcpCoalesceMaxSegs caps how many segments we'll coalesce into a single
-// superpacket. Keeping this well below the kernel's TSO ceiling bounds
-// latency.
-const tcpCoalesceMaxSegs = 64
-
-// tcpCoalesceHdrCap is the scratch space we copy a seed's IP+TCP header
-// into. IPv6 (40) + TCP with full options (60) = 100 bytes.
-const tcpCoalesceHdrCap = 100
-
-// coalesceSlot is one entry in the coalescer's ordered event queue. When
-// passthrough is true the slot holds a single borrowed packet that must be
-// emitted verbatim (non-TCP, non-admissible TCP, or oversize seed). When
-// passthrough is false the slot is an in-progress coalesced superpacket:
-// hdrBuf is a mutable copy of the seed's IP+TCP header (we patch total
-// length and pseudo-header partial at flush), and payIovs are *borrowed*
-// slices from the caller's plaintext buffers — no payload is ever copied.
-// The caller (listenOut) must keep those buffers alive until Flush.
-type coalesceSlot struct {
-	passthrough bool
-	rawPkt      []byte // borrowed when passthrough
-
-	fk       flowKey
-	hdrBuf   [tcpCoalesceHdrCap]byte
-	hdrLen   int
-	ipHdrLen int
-	isV6     bool
-	gsoSize  int
-	numSeg   int
-	totalPay int
-	nextSeq  uint32
-	// psh closes the chain: set when the last-accepted segment had PSH or
-	// was sub-gsoSize. No further appends after that.
-	psh     bool
-	payIovs [][]byte
-}
-
-// TCPCoalescer accumulates adjacent in-flow TCP data segments across
-// multiple concurrent flows and emits each flow's run as a single TSO
-// superpacket via tio.GSOWriter. All output — coalesced or not — is
-// deferred until Flush so arrival order is preserved on the wire. Owns
-// no locks; one coalescer per TUN write queue.
-type TCPCoalescer struct {
-	plainW io.Writer
-	gsoW   tio.GSOWriter // nil when the queue doesn't support TSO
-
-	// slots is the ordered event queue. Flush walks it once and emits each
-	// entry as either a WriteGSO (coalesced) or a plainW.Write (passthrough).
-	slots []*coalesceSlot
-	// openSlots maps a flow key to its most recent non-sealed slot, so new
-	// segments can extend an in-progress superpacket in O(1). Slots are
-	// removed from this map when they close (PSH or short-last-segment),
-	// when a non-admissible packet for that flow arrives, or in Flush.
-	openSlots map[flowKey]*coalesceSlot
-	// lastSlot caches the most recently touched open slot. Steady-state
-	// bulk traffic is dominated by a single flow, so comparing the
-	// incoming key against the cached slot's own fk lets the hot path
-	// skip the map lookup (and the aeshash of a 38-byte key) entirely.
-	// Kept in lockstep with openSlots: nil whenever the slot it pointed
-	// at is removed/sealed.
-	lastSlot *coalesceSlot
-	pool     []*coalesceSlot // free list for reuse
-
-	backing []byte
-}
-
-func NewTCPCoalescer(w io.Writer) *TCPCoalescer {
-	c := &TCPCoalescer{
-		plainW:    w,
-		slots:     make([]*coalesceSlot, 0, initialSlots),
-		openSlots: make(map[flowKey]*coalesceSlot, initialSlots),
-		pool:      make([]*coalesceSlot, 0, initialSlots),
-		backing:   make([]byte, 0, initialSlots*65535),
-	}
-	if gw, ok := tio.SupportsGSO(w, tio.GSOProtoTCP); ok {
-		c.gsoW = gw
-	}
-	return c
-}
-
-// parsedTCP holds the fields extracted from a single parse so later steps
-// (admission, slot lookup, canAppend) don't re-walk the header.
-type parsedTCP struct {
-	fk        flowKey
-	ipHdrLen  int
-	tcpHdrLen int
-	hdrLen    int
-	payLen    int
-	seq       uint32
-	flags     byte
-}
-
-// parseTCPBase extracts the flow key and IP/TCP offsets for any TCP packet,
-// regardless of whether it's admissible for coalescing. Returns ok=false
-// for non-TCP or malformed input. Accepts IPv4 (no options, no fragmentation)
-// and IPv6 (no extension headers).
-func parseTCPBase(pkt []byte) (parsedTCP, bool) {
-	var p parsedTCP
-	ip, ok := parseIPPrologue(pkt, ipProtoTCP)
-	if !ok {
-		return p, false
-	}
-	pkt = ip.pkt
-	p.fk = ip.fk
-	p.ipHdrLen = ip.ipHdrLen
-
-	if len(pkt) < p.ipHdrLen+20 {
-		return p, false
-	}
-	tcpOff := int(pkt[p.ipHdrLen+12]>>4) * 4
-	if tcpOff < 20 || tcpOff > 60 {
-		return p, false
-	}
-	if len(pkt) < p.ipHdrLen+tcpOff {
-		return p, false
-	}
-	p.tcpHdrLen = tcpOff
-	p.hdrLen = p.ipHdrLen + tcpOff
-	p.payLen = len(pkt) - p.hdrLen
-	p.seq = binary.BigEndian.Uint32(pkt[p.ipHdrLen+4 : p.ipHdrLen+8])
-	p.flags = pkt[p.ipHdrLen+13]
-	p.fk.sport = binary.BigEndian.Uint16(pkt[p.ipHdrLen : p.ipHdrLen+2])
-	p.fk.dport = binary.BigEndian.Uint16(pkt[p.ipHdrLen+2 : p.ipHdrLen+4])
-	return p, true
-}
-
-// TCP flag bits (byte 13 of the TCP header). Only the bits actually consulted
-// by the coalescer are named; FIN/SYN/RST/URG/CWR are rejected via the
-// negative mask in coalesceable, not by name.
-const (
-	tcpFlagPsh = 0x08
-	tcpFlagAck = 0x10
-	tcpFlagEce = 0x40
-)
-
-// coalesceable reports whether a parsed TCP segment is eligible for
-// coalescing. Accepts ACK, ACK|PSH, ACK|ECE, ACK|PSH|ECE with a
-// non-empty payload. CWR is excluded because it marks a one-shot
-// congestion-window-reduced transition the receiver must observe at a
-// segment boundary.
-func (p parsedTCP) coalesceable() bool {
-	if p.flags&tcpFlagAck == 0 {
-		return false
-	}
-	if p.flags&^(tcpFlagAck|tcpFlagPsh|tcpFlagEce) != 0 {
-		return false
-	}
-	return p.payLen > 0
-}
-
-func (c *TCPCoalescer) Reserve(sz int) []byte {
-	return reserveFromBacking(&c.backing, sz)
-}
-
-// Commit borrows pkt. The caller must keep pkt valid until the next Flush,
-// whether or not the packet was coalesced — passthrough (non-admissible)
-// packets are queued and written at Flush time, not synchronously.
-func (c *TCPCoalescer) Commit(pkt []byte) error {
-	if c.gsoW == nil {
-		c.addPassthrough(pkt)
-		return nil
-	}
-	info, ok := parseTCPBase(pkt)
-	if !ok {
-		c.addPassthrough(pkt)
-		return nil
-	}
-	return c.commitParsed(pkt, info)
-}
-
-// commitParsed is the post-parse half of Commit. The caller must have
-// already verified parseTCPBase succeeded (info is a valid TCP parse).
-// Used by MultiCoalescer.Commit to avoid re-walking the IP/TCP header
-// after the dispatcher has already done so.
-func (c *TCPCoalescer) commitParsed(pkt []byte, info parsedTCP) error {
-	if c.gsoW == nil {
-		c.addPassthrough(pkt)
-		return nil
-	}
-	if !info.coalesceable() {
-		// TCP but not admissible (SYN/FIN/RST/URG/CWR or zero-payload).
-		// Seal this flow's open slot so later in-flow packets don't extend
-		// it and accidentally reorder past this passthrough.
-		if last := c.lastSlot; last != nil && last.fk == info.fk {
-			c.lastSlot = nil
-		}
-		delete(c.openSlots, info.fk)
-		c.addPassthrough(pkt)
-		return nil
-	}
-
-	// Single-flow fast path: with only one open flow the cache hits every
-	// packet, and len(openSlots)==1 lets us skip the 38-byte fk compare
-	// when there are multiple flows in flight (where the hit rate would
-	// be ~0 and the compare is pure overhead).
-	var open *coalesceSlot
-	if last := c.lastSlot; last != nil && len(c.openSlots) == 1 && last.fk == info.fk {
-		open = last
-	} else {
-		open = c.openSlots[info.fk]
-	}
-	if open != nil {
-		if c.canAppend(open, pkt, info) {
-			c.appendPayload(open, pkt, info)
-			if open.psh {
-				delete(c.openSlots, info.fk)
-				c.lastSlot = nil
-			} else {
-				c.lastSlot = open
-			}
-			return nil
-		}
-		// Can't extend — seal it and fall through to seed a fresh slot.
-		delete(c.openSlots, info.fk)
-		if c.lastSlot == open {
-			c.lastSlot = nil
-		}
-	}
-	c.seed(pkt, info)
-	return nil
-}
-
-// Flush emits every queued event in (per-flow) seq order. Coalesced slots
-// go out via WriteGSO; passthrough slots go out via plainW.Write.
-// reorderForFlush first sorts each flow's slots into TCP-seq order within
-// passthrough-bounded segments and merges contiguous adjacent slots, so
-// any wire-side reorder that crossed an rxOrder batch boundary doesn't
-// get amplified into kernel-visible reorder by the slot machinery.
-// Returns the first error observed; keeps draining so one bad packet
-// doesn't hold up the rest. After Flush returns, borrowed payload slices
-// may be recycled.
-func (c *TCPCoalescer) Flush() error {
-	c.reorderForFlush()
-	var first error
-	for _, s := range c.slots {
-		var err error
-		if s.passthrough {
-			_, err = c.plainW.Write(s.rawPkt)
-		} else {
-			err = c.flushSlot(s)
-		}
-		if err != nil && first == nil {
-			first = err
-		}
-		c.release(s)
-	}
-	clear(c.slots)
-	c.slots = c.slots[:0]
-	clear(c.openSlots)
-	c.lastSlot = nil
-
-	c.backing = c.backing[:0]
-	return first
-}
-
-func (c *TCPCoalescer) addPassthrough(pkt []byte) {
-	s := c.take()
-	s.passthrough = true
-	s.rawPkt = pkt
-	c.slots = append(c.slots, s)
-}
-
-func (c *TCPCoalescer) seed(pkt []byte, info parsedTCP) {
-	if info.hdrLen > tcpCoalesceHdrCap || info.hdrLen+info.payLen > tcpCoalesceBufSize {
-		// Pathological shape — can't fit our scratch, emit as-is.
-		c.addPassthrough(pkt)
-		return
-	}
-	s := c.take()
-	s.passthrough = false
-	s.rawPkt = nil
-	copy(s.hdrBuf[:], pkt[:info.hdrLen])
-	s.hdrLen = info.hdrLen
-	s.ipHdrLen = info.ipHdrLen
-	s.isV6 = info.fk.isV6
-	s.fk = info.fk
-	s.gsoSize = info.payLen
-	s.numSeg = 1
-	s.totalPay = info.payLen
-	s.nextSeq = info.seq + uint32(info.payLen)
-	s.psh = info.flags&tcpFlagPsh != 0
-	s.payIovs = append(s.payIovs[:0], pkt[info.hdrLen:info.hdrLen+info.payLen])
-	c.slots = append(c.slots, s)
-	if !s.psh {
-		c.openSlots[info.fk] = s
-		c.lastSlot = s
-	} else if last := c.lastSlot; last != nil && last.fk == info.fk {
-		// PSH-on-seed seals the slot immediately. Any prior cached open
-		// slot for this flow has just been sealed-and-replaced by this
-		// passthrough-shaped seed, so drop the cache too.
-		c.lastSlot = nil
-	}
-}
-
-// canAppend reports whether info's packet extends the slot's seed: same
-// header shape and stable contents, adjacent seq, not oversized, chain not
-// closed.
-func (c *TCPCoalescer) canAppend(s *coalesceSlot, pkt []byte, info parsedTCP) bool {
-	if s.psh {
-		return false
-	}
-	if info.hdrLen != s.hdrLen {
-		return false
-	}
-	if info.seq != s.nextSeq {
-		return false
-	}
-	if s.numSeg >= tcpCoalesceMaxSegs {
-		return false
-	}
-	if info.payLen > s.gsoSize {
-		return false
-	}
-	if s.hdrLen+s.totalPay+info.payLen > tcpCoalesceBufSize {
-		return false
-	}
-	// ECE state must be stable across a burst — receivers expect the
-	// flag set on every segment of a CE-echoing window or none.
-	seedFlags := s.hdrBuf[s.ipHdrLen+13]
-	if (seedFlags^info.flags)&tcpFlagEce != 0 {
-		return false
-	}
-	if !headersMatch(s.hdrBuf[:s.hdrLen], pkt[:info.hdrLen], s.isV6, s.ipHdrLen) {
-		return false
-	}
-	return true
-}
-
-func (c *TCPCoalescer) appendPayload(s *coalesceSlot, pkt []byte, info parsedTCP) {
-	s.payIovs = append(s.payIovs, pkt[info.hdrLen:info.hdrLen+info.payLen])
-	s.numSeg++
-	s.totalPay += info.payLen
-	s.nextSeq = info.seq + uint32(info.payLen)
-	if info.flags&tcpFlagPsh != 0 {
-		// Propagate PSH into the seed header so kernel TSO sets it on the
-		// last segment. Without this the sender's push signal is dropped.
-		s.hdrBuf[s.ipHdrLen+13] |= tcpFlagPsh
-	}
-	// Merge IP-level CE marks into the seed: headersMatch ignores ECN, so
-	// this is the one place the signal is preserved.
-	mergeECNIntoSeed(s.hdrBuf[:s.ipHdrLen], pkt[:s.ipHdrLen], s.isV6)
-	if info.payLen < s.gsoSize || info.flags&tcpFlagPsh != 0 {
-		s.psh = true
-	}
-}
-
-func (c *TCPCoalescer) take() *coalesceSlot {
-	if n := len(c.pool); n > 0 {
-		s := c.pool[n-1]
-		c.pool[n-1] = nil
-		c.pool = c.pool[:n-1]
-		return s
-	}
-	return &coalesceSlot{}
-}
-
-func (c *TCPCoalescer) release(s *coalesceSlot) {
-	s.passthrough = false
-	s.rawPkt = nil
-	clear(s.payIovs)
-	s.payIovs = s.payIovs[:0]
-	s.numSeg = 0
-	s.totalPay = 0
-	s.psh = false
-	c.pool = append(c.pool, s)
-}
-
-// flushSlot patches the header and calls WriteGSO. Does not remove the
-// slot from c.slots.
-func (c *TCPCoalescer) flushSlot(s *coalesceSlot) error {
-	total := s.hdrLen + s.totalPay
-	l4Len := total - s.ipHdrLen
-	hdr := s.hdrBuf[:s.hdrLen]
-
-	if s.isV6 {
-		binary.BigEndian.PutUint16(hdr[4:6], uint16(l4Len))
-	} else {
-		binary.BigEndian.PutUint16(hdr[2:4], uint16(total))
-		hdr[10] = 0
-		hdr[11] = 0
-		binary.BigEndian.PutUint16(hdr[10:12], ipv4HdrChecksum(hdr[:s.ipHdrLen]))
-	}
-
-	var psum uint32
-	if s.isV6 {
-		psum = pseudoSumIPv6(hdr[8:24], hdr[24:40], ipProtoTCP, l4Len)
-	} else {
-		psum = pseudoSumIPv4(hdr[12:16], hdr[16:20], ipProtoTCP, l4Len)
-	}
-	tcsum := s.ipHdrLen + 16
-	binary.BigEndian.PutUint16(hdr[tcsum:tcsum+2], foldOnceNoInvert(psum))
-
-	return c.gsoW.WriteGSO(hdr[:s.ipHdrLen], hdr[s.ipHdrLen:], s.payIovs, tio.GSOProtoTCP)
-}
-
-// headersMatch compares two IP+TCP header prefixes for byte-for-byte
-// equality on every field that must be identical across coalesced
-// segments. Size/IPID/IPCsum/seq/flags/tcpCsum are masked out, as is the
-// 2-bit IP-level ECN field — appendPayload merges CE into the seed.
-func headersMatch(a, b []byte, isV6 bool, ipHdrLen int) bool {
-	if len(a) != len(b) {
-		return false
-	}
-	if !ipHeadersMatch(a, b, isV6) {
-		return false
-	}
-	// TCP: compare [0:4] ports, [8:13] ack+dataoff, [14:16] window,
-	// [18:tcpHdrLen] options (incl. urgent).
-	tcp := ipHdrLen
-	if !bytes.Equal(a[tcp:tcp+4], b[tcp:tcp+4]) {
-		return false
-	}
-	if !bytes.Equal(a[tcp+8:tcp+13], b[tcp+8:tcp+13]) {
-		return false
-	}
-	if !bytes.Equal(a[tcp+14:tcp+16], b[tcp+14:tcp+16]) {
-		return false
-	}
-	if !bytes.Equal(a[tcp+18:], b[tcp+18:]) {
-		return false
-	}
-	return true
-}
-
-// reorderForFlush neutralizes wire-side reorder that the rxOrder buffer
-// couldn't catch (anything crossing a recvmmsg batch boundary). Without
-// this pass a small wire reorder — counter 250 arriving in batch K when
-// 200..249 are coming in batch K+1 — would seed an out-of-seq slot first
-// and emit it ahead of the lower-seq slot, manifesting at the inner TCP
-// receiver as a much larger reorder than the wire actually had.
-//
-// Two phases:
-//  1. Sort each passthrough-bounded segment of c.slots by (flow, seq).
-//     Cross-flow ordering inside a segment isn't preserved (it never was
-//     and doesn't matter for any single flow's TCP correctness).
-//  2. Sweep once and merge adjacent same-flow slots whose ranges are now
-//     contiguous AND whose tail is gsoSize-aligned. The tail constraint
-//     matters because the kernel TSO splitter chops at gsoSize from the
-//     start of the merged payload — a short segment in the middle would
-//     desynchronize every later segment.
-//
-// Passthrough slots act as barriers: the merge check skips them on either
-// side, so a SYN/FIN/RST/CWR is never reordered relative to its flow's
-// data.
-func (c *TCPCoalescer) reorderForFlush() {
-	if len(c.slots) <= 1 {
-		return
-	}
-	runStart := 0
-	for i := 0; i <= len(c.slots); i++ {
-		if i < len(c.slots) && !c.slots[i].passthrough {
-			continue
-		}
-		c.sortRun(c.slots[runStart:i])
-		runStart = i + 1
-	}
-	out := c.slots[:0]
-	logged := false
-	for _, s := range c.slots {
-		if n := len(out); n > 0 {
-			prev := out[n-1]
-			if !prev.passthrough && !s.passthrough && prev.fk == s.fk {
-				// Same-flow neighbors after sort. If they aren't seq-
-				// contiguous it's a real gap — packets the wire reordered
-				// across batches, or actual loss before nebula. Log it so
-				// the operator can quantify how often it happens; the data
-				// itself still emits in seq order, kernel TCP handles the
-				// gap via its OOO queue.
-				if prev.nextSeq != slotSeedSeq(s) {
-					logged = true
-					gap := int64(slotSeedSeq(s)) - int64(prev.nextSeq)
-					slog.Default().Warn("tcp coalesce: cross-slot seq gap",
-						"src", flowKeyAddr(s.fk, false),
-						"dst", flowKeyAddr(s.fk, true),
-						"sport", s.fk.sport,
-						"dport", s.fk.dport,
-						"prev_seed_seq", slotSeedSeq(prev),
-						"prev_next_seq", prev.nextSeq,
-						"this_seed_seq", slotSeedSeq(s),
-						"gap_bytes", gap,
-						"prev_seg_count", prev.numSeg,
-						"prev_total_pay", prev.totalPay,
-					)
-				}
-				if canMergeSlots(prev, s) {
-					mergeSlots(prev, s)
-					c.release(s)
-					continue
-				}
-			}
-		}
-		out = append(out, s)
-	}
-	if logged {
-		slog.Default().Warn("==== end of batch ====")
-	}
-	c.slots = out
-}
-
-// flowKeyAddr returns the src or dst address from fk as a netip.Addr for
-// logging. Only used on the cold gap-log path so the netip allocation
-// doesn't matter.
-func flowKeyAddr(fk flowKey, dst bool) netip.Addr {
-	src := fk.src
-	if dst {
-		src = fk.dst
-	}
-	if fk.isV6 {
-		return netip.AddrFrom16(src)
-	}
-	var v4 [4]byte
-	copy(v4[:], src[:4])
-	return netip.AddrFrom4(v4)
-}
-
-// sortRun stable-sorts run by (flowKey, seedSeq) so each flow's slots
-// cluster together in seq order, ready for the merge sweep. Stable so
-// equal-key slots keep their original relative position (defensive — a
-// duplicate seedSeq would already mean something's wrong upstream).
-func (c *TCPCoalescer) sortRun(run []*coalesceSlot) {
-	if len(run) <= 1 {
-		return
-	}
-	// slices.SortStableFunc with a free, non-capturing comparator avoids the
-	// reflection + closure-escape allocations that sort.SliceStable forces.
-	slices.SortStableFunc(run, compareCoalesceSlots)
-}
-
-func compareCoalesceSlots(a, b *coalesceSlot) int {
-	if cmp := flowKeyCompare(a.fk, b.fk); cmp != 0 {
-		return cmp
-	}
-	aSeq, bSeq := slotSeedSeq(a), slotSeedSeq(b)
-	if aSeq == bSeq {
-		return 0
-	}
-	if tcpSeqLess(aSeq, bSeq) {
-		return -1
-	}
-	return 1
-}
-
-// slotSeedSeq returns the TCP seq of the slot's seed (first segment).
-// nextSeq tracks the seq just past the last appended byte; subtracting
-// totalPay walks back to the seed. uint32 wraparound is the right TCP
-// arithmetic so no special-casing is needed.
-func slotSeedSeq(s *coalesceSlot) uint32 {
-	return s.nextSeq - uint32(s.totalPay)
-}
-
-// tcpSeqLess reports whether a precedes b in TCP serial-number arithmetic
-// (RFC 1323 §2.3). The signed int32 cast turns the modular subtraction
-// into the right comparison even across the 2^32 wrap.
-func tcpSeqLess(a, b uint32) bool {
-	return int32(a-b) < 0
-}
-
-// flowKeyCompare orders flowKeys deterministically. The exact ordering
-// is irrelevant — only that same-flow slots cluster together so the
-// post-sort sweep can merge contiguous pairs.
-func flowKeyCompare(a, b flowKey) int {
-	// Cheap scalar fields first so most non-matching keys short-circuit
-	// without ever calling bytes.Compare. sport is the ephemeral port on
-	// egress flows and discriminates fastest. For matching keys (same
-	// flow), array equality on src/dst inlines to word-sized compares,
-	// so we only pay bytes.Compare when the arrays actually differ.
-	if a.sport != b.sport {
-		if a.sport < b.sport {
-			return -1
-		}
-		return 1
-	}
-	if a.dport != b.dport {
-		if a.dport < b.dport {
-			return -1
-		}
-		return 1
-	}
-	if a.dst != b.dst {
-		return bytes.Compare(a.dst[:], b.dst[:])
-	}
-	if a.src != b.src {
-		return bytes.Compare(a.src[:], b.src[:])
-	}
-	if a.isV6 != b.isV6 {
-		if !a.isV6 {
-			return -1
-		}
-		return 1
-	}
-	return 0
-}
-
-// canMergeSlots reports whether s can fold into prev as one merged TSO
-// superpacket. Same flow, contiguous TCP byte range, equal gsoSize, and
-// fits within the kernel TSO limits. The tail-of-prev check rejects any
-// merge whose first slot ended on a sub-gsoSize segment — kernel TSO
-// would split the merged skb at gsoSize boundaries from the start, so a
-// short segment in the middle would corrupt every later segment. PSH and
-// ECE state must agree across both slots: PSH is a semantic delimiter
-// (preserving the sender's push boundary) and ECE state must be uniform
-// across a window (the same rule canAppend enforces for in-flow appends).
-//
-// Note: a slot sealed by reorder (canAppend returned false on seq
-// mismatch) keeps psh=false, so this restriction does not block the
-// reorder-fix merge — only legitimate PSH-set seals.
-func canMergeSlots(prev, s *coalesceSlot) bool {
-	if prev.psh {
-		return false
-	}
-	if prev.fk != s.fk {
-		return false
-	}
-	if prev.gsoSize != s.gsoSize {
-		return false
-	}
-	if prev.nextSeq != slotSeedSeq(s) {
-		return false
-	}
-	if prev.numSeg+s.numSeg > tcpCoalesceMaxSegs {
-		return false
-	}
-	if prev.hdrLen+prev.totalPay+s.totalPay > tcpCoalesceBufSize {
-		return false
-	}
-	if len(prev.payIovs[len(prev.payIovs)-1]) != prev.gsoSize {
-		return false
-	}
-	prevFlags := prev.hdrBuf[prev.ipHdrLen+13]
-	sFlags := s.hdrBuf[s.ipHdrLen+13]
-	if (prevFlags^sFlags)&tcpFlagEce != 0 {
-		return false
-	}
-	if !headersMatch(prev.hdrBuf[:prev.hdrLen], s.hdrBuf[:s.hdrLen], prev.isV6, prev.ipHdrLen) {
-		return false
-	}
-	return true
-}
-
-// mergeSlots folds src into dst in place: payIovs concatenated, counters
-// and totals updated, PSH and IP-level CE bits OR'd into the seed header
-// so neither the push signal nor a CE mark is lost. The seed header's
-// seq, gsoSize, and fk are unchanged. Caller is responsible for releasing
-// src (it's no longer in c.slots after this call).
-func mergeSlots(dst, src *coalesceSlot) {
-	dst.payIovs = append(dst.payIovs, src.payIovs...)
-	dst.numSeg += src.numSeg
-	dst.totalPay += src.totalPay
-	dst.nextSeq = src.nextSeq
-	if src.psh {
-		dst.psh = true
-		dst.hdrBuf[dst.ipHdrLen+13] |= tcpFlagPsh
-	}
-	mergeECNIntoSeed(dst.hdrBuf[:dst.ipHdrLen], src.hdrBuf[:src.ipHdrLen], dst.isV6)
-}
-
-// ipv4HdrChecksum computes the IPv4 header checksum over hdr (which must
-// already have its checksum field zeroed) and returns the folded/inverted
-// 16-bit value to store.
-func ipv4HdrChecksum(hdr []byte) uint16 {
-	var sum uint32
-	for i := 0; i+1 < len(hdr); i += 2 {
-		sum += uint32(binary.BigEndian.Uint16(hdr[i : i+2]))
-	}
-	if len(hdr)%2 == 1 {
-		sum += uint32(hdr[len(hdr)-1]) << 8
-	}
-	for sum>>16 != 0 {
-		sum = (sum & 0xffff) + (sum >> 16)
-	}
-	return ^uint16(sum)
-}
-
-// pseudoSumIPv4 / pseudoSumIPv6 build the L4 pseudo-header partial sum
-// expected by the virtio NEEDS_CSUM kernel path: the 32-bit accumulator
-// before folding. proto selects the L4 (TCP or UDP); the UDP coalescer
-// reuses these helpers.
-func pseudoSumIPv4(src, dst []byte, proto byte, l4Len int) uint32 {
-	var sum uint32
-	sum += uint32(binary.BigEndian.Uint16(src[0:2]))
-	sum += uint32(binary.BigEndian.Uint16(src[2:4]))
-	sum += uint32(binary.BigEndian.Uint16(dst[0:2]))
-	sum += uint32(binary.BigEndian.Uint16(dst[2:4]))
-	sum += uint32(proto)
-	sum += uint32(l4Len)
-	return sum
-}
-
-func pseudoSumIPv6(src, dst []byte, proto byte, l4Len int) uint32 {
-	var sum uint32
-	for i := 0; i < 16; i += 2 {
-		sum += uint32(binary.BigEndian.Uint16(src[i : i+2]))
-		sum += uint32(binary.BigEndian.Uint16(dst[i : i+2]))
-	}
-	sum += uint32(l4Len >> 16)
-	sum += uint32(l4Len & 0xffff)
-	sum += uint32(proto)
-	return sum
-}
-
-// foldOnceNoInvert folds the 32-bit accumulator to 16 bits and returns it
-// unchanged (no one's complement). This is what virtio NEEDS_CSUM wants in
-// the L4 checksum field — the kernel will add the payload sum and invert.
-func foldOnceNoInvert(sum uint32) uint16 {
-	for sum>>16 != 0 {
-		sum = (sum & 0xffff) + (sum >> 16)
-	}
-	return uint16(sum)
-}

overlay/batch/tcp_coalesce_bench_test.go

@@ -1,239 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"runtime"
-	"testing"
-
-	"github.com/slackhq/nebula/overlay/tio"
-)
-
-// nopTunWriter is a zero-alloc tio.GSOWriter for benchmarks. Discards
-// everything but satisfies the interface the coalescer detects.
-type nopTunWriter struct{}
-
-func (nopTunWriter) Write(p []byte) (int, error) { return len(p), nil }
-func (nopTunWriter) WriteGSO(hdr []byte, transportHdr []byte, pays [][]byte, _ tio.GSOProto) error {
-	return nil
-}
-func (nopTunWriter) Capabilities() tio.Capabilities {
-	return tio.Capabilities{TSO: true, USO: true}
-}
-
-// buildTCPv4BulkFlow returns a slice of N adjacent ACK-only TCP segments
-// on a single 5-tuple, each carrying payloadLen bytes. Seq numbers are
-// contiguous so every packet is coalesceable onto the previous one.
-func buildTCPv4BulkFlow(n, payloadLen int) [][]byte {
-	pkts := make([][]byte, n)
-	pay := make([]byte, payloadLen)
-	seq := uint32(1000)
-	for i := range n {
-		pkts[i] = buildTCPv4(seq, tcpAck, pay)
-		seq += uint32(payloadLen)
-	}
-	return pkts
-}
-
-// buildTCPv4Interleaved returns nFlows * perFlow packets with per-flow
-// seq continuity but round-robin across flows — worst case for any
-// "last-slot" cache.
-func buildTCPv4Interleaved(nFlows, perFlow, payloadLen int) [][]byte {
-	pay := make([]byte, payloadLen)
-	seqs := make([]uint32, nFlows)
-	for i := range seqs {
-		seqs[i] = uint32(1000 + i*1000000)
-	}
-	pkts := make([][]byte, 0, nFlows*perFlow)
-	for range perFlow {
-		for f := range nFlows {
-			sport := uint16(10000 + f)
-			pkts = append(pkts, buildTCPv4Ports(sport, 2000, seqs[f], tcpAck, pay))
-			seqs[f] += uint32(payloadLen)
-		}
-	}
-	return pkts
-}
-
-// buildICMPv4 returns a minimal non-TCP packet that takes the passthrough
-// branch in Commit.
-func buildICMPv4() []byte {
-	pkt := make([]byte, 28)
-	pkt[0] = 0x45
-	binary.BigEndian.PutUint16(pkt[2:4], 28)
-	pkt[9] = 1 // ICMP
-	copy(pkt[12:16], []byte{10, 0, 0, 1})
-	copy(pkt[16:20], []byte{10, 0, 0, 2})
-	return pkt
-}
-
-// runCommitBench drives Commit over pkts batchSize at a time, flushing
-// between batches, and reports per-packet cost.
-func runCommitBench(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	c := NewTCPCoalescer(nopTunWriter{})
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		pkt := pkts[i%len(pkts)]
-		if err := c.Commit(pkt); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			if err := c.Flush(); err != nil {
-				b.Fatal(err)
-			}
-		}
-	}
-	// Drain any trailing partial batch so slot state doesn't leak across runs.
-	_ = c.Flush()
-}
-
-// BenchmarkCommitSingleFlow is the bulk-TCP steady state: one flow,
-// contiguous seq, 1200-byte payloads. Every packet past the seed should
-// append onto the open slot. This is the case we most care about.
-func BenchmarkCommitSingleFlow(b *testing.B) {
-	pkts := buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200)
-	runCommitBench(b, pkts, tcpCoalesceMaxSegs)
-}
-
-// BenchmarkCommitInterleaved4 has 4 concurrent bulk flows round-robined.
-// A single-entry fast-path cache will miss on every packet; an N-way
-// cache or map lookup carries the weight.
-func BenchmarkCommitInterleaved4(b *testing.B) {
-	pkts := buildTCPv4Interleaved(4, tcpCoalesceMaxSegs, 1200)
-	runCommitBench(b, pkts, len(pkts))
-}
-
-// BenchmarkCommitInterleaved16 stresses the map at higher flow counts.
-func BenchmarkCommitInterleaved16(b *testing.B) {
-	pkts := buildTCPv4Interleaved(16, tcpCoalesceMaxSegs, 1200)
-	runCommitBench(b, pkts, len(pkts))
-}
-
-// BenchmarkCommitPassthrough exercises the non-TCP branch: parseTCPBase
-// bails early and addPassthrough is the only work.
-func BenchmarkCommitPassthrough(b *testing.B) {
-	pkt := buildICMPv4()
-	pkts := make([][]byte, 64)
-	for i := range pkts {
-		pkts[i] = pkt
-	}
-	runCommitBench(b, pkts, 64)
-}
-
-// BenchmarkCommitNonCoalesceableTCP sends SYN|ACK packets on one flow.
-// Each packet takes the "TCP but not admissible" branch which does a
-// map delete + passthrough. Measures the seal-without-slot cost.
-func BenchmarkCommitNonCoalesceableTCP(b *testing.B) {
-	pay := make([]byte, 0)
-	pkts := make([][]byte, 64)
-	for i := range pkts {
-		pkts[i] = buildTCPv4(uint32(1000+i), tcpSyn|tcpAck, pay)
-	}
-	runCommitBench(b, pkts, 64)
-}
-
-// runMultiCommitBench drives MultiCoalescer.Commit. The dispatcher does
-// the IP/L4 parse once and passes the parsed struct to the lane, so this
-// is the bench that shows the savings of skipping the lane's re-parse.
-func runMultiCommitBench(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, true, true)
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		pkt := pkts[i%len(pkts)]
-		if err := m.Commit(pkt); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			if err := m.Flush(); err != nil {
-				b.Fatal(err)
-			}
-		}
-	}
-	_ = m.Flush()
-}
-
-// BenchmarkMultiCommitSingleFlow is the multi-lane analogue of
-// BenchmarkCommitSingleFlow — same workload but routed through the
-// dispatcher. The delta vs the single-lane bench measures dispatcher
-// overhead.
-func BenchmarkMultiCommitSingleFlow(b *testing.B) {
-	pkts := buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200)
-	runMultiCommitBench(b, pkts, tcpCoalesceMaxSegs)
-}
-
-// BenchmarkMultiCommitInterleaved4 mirrors BenchmarkCommitInterleaved4
-// through the dispatcher.
-func BenchmarkMultiCommitInterleaved4(b *testing.B) {
-	pkts := buildTCPv4Interleaved(4, tcpCoalesceMaxSegs, 1200)
-	runMultiCommitBench(b, pkts, len(pkts))
-}
-
-// flowKeyPair is one comparison input for the flowKeyCompare bench.
-type flowKeyPair struct{ a, b flowKey }
-
-// makeFlowKey builds an IPv4 flowKey from compact inputs.
-func makeFlowKey(srcLow, dstLow uint32, sport, dport uint16) flowKey {
-	var fk flowKey
-	binary.BigEndian.PutUint32(fk.src[12:16], srcLow)
-	binary.BigEndian.PutUint32(fk.dst[12:16], dstLow)
-	fk.sport = sport
-	fk.dport = dport
-	return fk
-}
-
-// flowKeyCases are the workload mixes flowKeyCompare sees in practice.
-//   - sameFlow: equal keys; tests the equal-path cost (sort runs hit this
-//     repeatedly when many segments share a flow).
-//   - sportDiffers: same src/dst/dport, different sport — the typical
-//     "sibling flows from one host to one server" pattern.
-//   - dstDiffers: same src/sport/dport, different dst — outbound to many
-//     servers from a fixed local port.
-//   - allDiffer: every field differs; worst case for short-circuiting.
-func flowKeyCases() map[string][]flowKeyPair {
-	const n = 64
-	cases := map[string][]flowKeyPair{
-		"sameFlow":     make([]flowKeyPair, n),
-		"sportDiffers": make([]flowKeyPair, n),
-		"dstDiffers":   make([]flowKeyPair, n),
-		"allDiffer":    make([]flowKeyPair, n),
-	}
-	for i := range n {
-		base := makeFlowKey(0x0a000001, 0x0a000002, 40000, 443)
-		cases["sameFlow"][i] = flowKeyPair{a: base, b: base}
-		cases["sportDiffers"][i] = flowKeyPair{
-			a: base,
-			b: makeFlowKey(0x0a000001, 0x0a000002, uint16(40001+i), 443),
-		}
-		cases["dstDiffers"][i] = flowKeyPair{
-			a: base,
-			b: makeFlowKey(0x0a000001, uint32(0x0a000002+i+1), 40000, 443),
-		}
-		cases["allDiffer"][i] = flowKeyPair{
-			a: makeFlowKey(uint32(0x0a000001+i), uint32(0x0a000002+i), uint16(40000+i), uint16(80+i)),
-			b: makeFlowKey(uint32(0x0b000001+i), uint32(0x0b000002+i), uint16(50000+i), uint16(443+i)),
-		}
-	}
-	return cases
-}
-
-// BenchmarkFlowKeyCompare measures flowKeyCompare across the workloads
-// the sort step actually sees. Use this to compare reorderings.
-func BenchmarkFlowKeyCompare(b *testing.B) {
-	for name, pairs := range flowKeyCases() {
-		b.Run(name, func(b *testing.B) {
-			b.ReportAllocs()
-			b.ResetTimer()
-			var sink int
-			for i := 0; i < b.N; i++ {
-				p := pairs[i&(len(pairs)-1)]
-				sink += flowKeyCompare(p.a, p.b)
-			}
-			runtime.KeepAlive(sink)
-		})
-	}
-}

overlay/batch/tx_batch.go

@@ -1,64 +0,0 @@
-package batch
-
-import "net/netip"
-
-const SendBatchCap = 128
-
-// batchWriter is the minimal subset of udp.Conn needed by SendBatch to flush.
-type batchWriter interface {
-	WriteBatch(bufs [][]byte, addrs []netip.AddrPort, outerECNs []byte) error
-}
-
-// SendBatch accumulates encrypted UDP packets and flushes them via WriteBatch.
-// One SendBatch is owned by each listenIn goroutine; no locking is needed.
-// The backing arena grows on demand: when there isn't room for the next slot
-// we allocate a fresh backing array. Already-committed slices keep referencing
-// the old array and remain valid until Flush drops them.
-type SendBatch struct {
-	out     batchWriter
-	bufs    [][]byte
-	dsts    []netip.AddrPort
-	ecns    []byte
-	backing []byte
-}
-
-func NewSendBatch(out batchWriter, batchCap, slotCap int) *SendBatch {
-	return &SendBatch{
-		out:     out,
-		bufs:    make([][]byte, 0, batchCap),
-		dsts:    make([]netip.AddrPort, 0, batchCap),
-		ecns:    make([]byte, 0, batchCap),
-		backing: make([]byte, 0, batchCap*slotCap),
-	}
-}
-
-func (b *SendBatch) Reserve(sz int) []byte {
-	if len(b.backing)+sz > cap(b.backing) {
-		// Grow: allocate a fresh backing. Already-committed slices still
-		// reference the old array and remain valid until Flush drops them.
-		newCap := max(cap(b.backing)*2, sz)
-		b.backing = make([]byte, 0, newCap)
-	}
-	start := len(b.backing)
-	b.backing = b.backing[:start+sz]
-	return b.backing[start : start+sz : start+sz]
-}
-
-func (b *SendBatch) Commit(pkt []byte, dst netip.AddrPort, outerECN byte) {
-	b.bufs = append(b.bufs, pkt)
-	b.dsts = append(b.dsts, dst)
-	b.ecns = append(b.ecns, outerECN)
-}
-
-func (b *SendBatch) Flush() error {
-	var err error
-	if len(b.bufs) > 0 {
-		err = b.out.WriteBatch(b.bufs, b.dsts, b.ecns)
-	}
-	clear(b.bufs)
-	b.bufs = b.bufs[:0]
-	b.dsts = b.dsts[:0]
-	b.ecns = b.ecns[:0]
-	b.backing = b.backing[:0]
-	return err
-}

overlay/batch/tx_batch_test.go

@@ -1,124 +0,0 @@
-package batch
-
-import (
-	"net/netip"
-	"testing"
-)
-
-type fakeBatchWriter struct {
-	bufs  [][]byte
-	addrs []netip.AddrPort
-	ecns  []byte
-}
-
-func (w *fakeBatchWriter) WriteBatch(bufs [][]byte, addrs []netip.AddrPort, ecns []byte) error {
-	// Snapshot — SendBatch.Flush nils its slot pointers right after WriteBatch
-	// returns, so tests must capture data before that happens.
-	w.bufs = make([][]byte, len(bufs))
-	for i, b := range bufs {
-		cp := make([]byte, len(b))
-		copy(cp, b)
-		w.bufs[i] = cp
-	}
-	w.addrs = append(w.addrs[:0], addrs...)
-	w.ecns = append(w.ecns[:0], ecns...)
-	return nil
-}
-
-func TestSendBatchReserveCommitFlush(t *testing.T) {
-	fw := &fakeBatchWriter{}
-	b := NewSendBatch(fw, 4, 32)
-
-	ap := netip.MustParseAddrPort("10.0.0.1:4242")
-	for i := 0; i < 4; i++ {
-		slot := b.Reserve(32)
-		if cap(slot) != 32 {
-			t.Fatalf("slot %d: cap=%d want 32", i, cap(slot))
-		}
-		pkt := append(slot[:0], byte(i), byte(i+1), byte(i+2))
-		b.Commit(pkt, ap, 0)
-	}
-	if err := b.Flush(); err != nil {
-		t.Fatalf("Flush: %v", err)
-	}
-	if len(fw.bufs) != 4 {
-		t.Fatalf("WriteBatch got %d bufs want 4", len(fw.bufs))
-	}
-	for i, buf := range fw.bufs {
-		if len(buf) != 3 || buf[0] != byte(i) {
-			t.Errorf("buf %d: %x", i, buf)
-		}
-		if fw.addrs[i] != ap {
-			t.Errorf("addr %d: got %v want %v", i, fw.addrs[i], ap)
-		}
-	}
-
-	// Flush again with nothing committed — should be a no-op.
-	fw.bufs = nil
-	if err := b.Flush(); err != nil {
-		t.Fatalf("empty Flush: %v", err)
-	}
-	if fw.bufs != nil {
-		t.Fatalf("empty Flush triggered WriteBatch")
-	}
-
-	// Reuse after Flush.
-	slot := b.Reserve(32)
-	if cap(slot) != 32 {
-		t.Fatalf("after Flush Reserve wrong cap: %d", cap(slot))
-	}
-}
-
-func TestSendBatchSlotsDoNotOverlap(t *testing.T) {
-	fw := &fakeBatchWriter{}
-	b := NewSendBatch(fw, 3, 8)
-	ap := netip.MustParseAddrPort("10.0.0.1:80")
-
-	for i := 0; i < 3; i++ {
-		s := b.Reserve(8)
-		pkt := append(s[:0], byte(0xA0+i), byte(0xB0+i))
-		b.Commit(pkt, ap, 0)
-	}
-	if err := b.Flush(); err != nil {
-		t.Fatalf("Flush: %v", err)
-	}
-
-	for i, buf := range fw.bufs {
-		if buf[0] != byte(0xA0+i) || buf[1] != byte(0xB0+i) {
-			t.Errorf("slot %d corrupted: %x", i, buf)
-		}
-	}
-}
-
-func TestSendBatchGrowPreservesCommitted(t *testing.T) {
-	fw := &fakeBatchWriter{}
-	// Tiny initial backing forces a grow on the second Reserve.
-	b := NewSendBatch(fw, 1, 4)
-	ap := netip.MustParseAddrPort("10.0.0.1:80")
-
-	s1 := b.Reserve(4)
-	pkt1 := append(s1[:0], 0x11, 0x22, 0x33, 0x44)
-	b.Commit(pkt1, ap, 0)
-
-	s2 := b.Reserve(8) // exceeds remaining cap, triggers grow
-	pkt2 := append(s2[:0], 0xA, 0xB, 0xC, 0xD, 0xE)
-	b.Commit(pkt2, ap, 0)
-
-	// pkt1 must still be intact even though backing reallocated.
-	if pkt1[0] != 0x11 || pkt1[3] != 0x44 {
-		t.Fatalf("first packet corrupted by grow: %x", pkt1)
-	}
-
-	if err := b.Flush(); err != nil {
-		t.Fatalf("Flush: %v", err)
-	}
-	if len(fw.bufs) != 2 {
-		t.Fatalf("got %d bufs want 2", len(fw.bufs))
-	}
-	if fw.bufs[0][0] != 0x11 || fw.bufs[0][3] != 0x44 {
-		t.Errorf("first packet on the wire: %x", fw.bufs[0])
-	}
-	if fw.bufs[1][0] != 0xA || fw.bufs[1][4] != 0xE {
-		t.Errorf("second packet on the wire: %x", fw.bufs[1])
-	}
-}

overlay/batch/udp_coalesce.go

@@ -1,336 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"io"
-
-	"github.com/slackhq/nebula/overlay/tio"
-)
-
-// ipProtoUDP is the IANA protocol number for UDP.
-const ipProtoUDP = 17
-
-// udpCoalesceBufSize caps total bytes per UDP superpacket. Mirrors the
-// kernel's gso_max_size; payloads beyond this are emitted as-is.
-const udpCoalesceBufSize = 65535
-
-// udpCoalesceMaxSegs caps how many segments we'll coalesce. Kernel UDP-GSO
-// accepts up to 64 segments per skb (UDP_MAX_SEGMENTS); stay under that.
-const udpCoalesceMaxSegs = 64
-
-// udpCoalesceHdrCap is the scratch space we copy a seed's IP+UDP header
-// into. IPv6 (40) + UDP (8) = 48; round up for safety.
-const udpCoalesceHdrCap = 64
-
-// udpSlot is one entry in the UDPCoalescer's ordered event queue. Same
-// passthrough-vs-coalesced shape as the TCP coalescer's slot, but no
-// seq/PSH/CWR bookkeeping — UDP segments only need 5-tuple + length
-// matching to coalesce.
-type udpSlot struct {
-	passthrough bool
-	rawPkt      []byte // borrowed when passthrough
-
-	fk       flowKey
-	hdrBuf   [udpCoalesceHdrCap]byte
-	hdrLen   int
-	ipHdrLen int
-	isV6     bool
-	gsoSize  int // per-segment UDP payload length
-	numSeg   int
-	totalPay int
-	// sealed closes the chain: set when a sub-gsoSize segment is appended
-	// (kernel UDP-GSO requires every segment but the last to be exactly
-	// gsoSize) or when limits are hit. No further appends after.
-	sealed  bool
-	payIovs [][]byte
-}
-
-// UDPCoalescer accumulates adjacent in-flow UDP datagrams across multiple
-// concurrent flows and emits each flow's run as a single GSO_UDP_L4
-// superpacket via tio.GSOWriter. Falls back to per-packet writes when the
-// underlying writer doesn't support USO.
-//
-// All output — coalesced or not — is deferred until Flush so per-flow
-// arrival order is preserved on the wire. Cross-flow order is NOT preserved
-// across the TCP/UDP/passthrough split when this coalescer runs alongside
-// others — see multi_coalesce.go. Per-flow order is preserved because a
-// single 5-tuple only ever lands in one lane and each lane preserves its
-// own slot order.
-//
-// Owns no locks; one coalescer per TUN write queue.
-type UDPCoalescer struct {
-	plainW io.Writer
-	gsoW   tio.GSOWriter // nil when the queue can't accept GSO_UDP_L4
-
-	slots     []*udpSlot
-	openSlots map[flowKey]*udpSlot
-	pool      []*udpSlot
-
-	backing []byte
-}
-
-// NewUDPCoalescer wraps w. The caller is responsible for only constructing
-// this when the underlying Queue's Capabilities advertise USO; otherwise
-// the kernel may reject GSO_UDP_L4 writes. If w does not implement
-// tio.GSOWriter at all (single-packet Queue), the coalescer degrades to
-// plain Writes — same defensive shape as the TCP coalescer.
-func NewUDPCoalescer(w io.Writer) *UDPCoalescer {
-	c := &UDPCoalescer{
-		plainW:    w,
-		slots:     make([]*udpSlot, 0, initialSlots),
-		openSlots: make(map[flowKey]*udpSlot, initialSlots),
-		pool:      make([]*udpSlot, 0, initialSlots),
-		backing:   make([]byte, 0, initialSlots*udpCoalesceBufSize),
-	}
-	if gw, ok := tio.SupportsGSO(w, tio.GSOProtoUDP); ok {
-		c.gsoW = gw
-	}
-	return c
-}
-
-// parsedUDP holds the fields extracted from a single parse so later steps
-// (admission, slot lookup, canAppend) don't re-walk the header.
-type parsedUDP struct {
-	fk       flowKey
-	ipHdrLen int
-	hdrLen   int // ipHdrLen + 8
-	payLen   int
-}
-
-// parseUDP extracts the flow key and IP/UDP offsets for a UDP packet.
-// Returns ok=false for non-UDP, malformed, or unsupported header shapes
-// (IPv4 with options/fragmentation, IPv6 with extension headers).
-func parseUDP(pkt []byte) (parsedUDP, bool) {
-	var p parsedUDP
-	ip, ok := parseIPPrologue(pkt, ipProtoUDP)
-	if !ok {
-		return p, false
-	}
-	pkt = ip.pkt
-	p.fk = ip.fk
-	p.ipHdrLen = ip.ipHdrLen
-
-	if len(pkt) < p.ipHdrLen+8 {
-		return p, false
-	}
-	p.hdrLen = p.ipHdrLen + 8
-	// UDP `length` field: must equal IP-derived length-of-UDP-header-plus-payload.
-	udpLen := int(binary.BigEndian.Uint16(pkt[p.ipHdrLen+4 : p.ipHdrLen+6]))
-	if udpLen < 8 || udpLen > len(pkt)-p.ipHdrLen {
-		return p, false
-	}
-	p.payLen = udpLen - 8
-	p.fk.sport = binary.BigEndian.Uint16(pkt[p.ipHdrLen : p.ipHdrLen+2])
-	p.fk.dport = binary.BigEndian.Uint16(pkt[p.ipHdrLen+2 : p.ipHdrLen+4])
-	return p, true
-}
-
-func (c *UDPCoalescer) Reserve(sz int) []byte {
-	return reserveFromBacking(&c.backing, sz)
-}
-
-// Commit borrows pkt. The caller must keep pkt valid until the next Flush.
-func (c *UDPCoalescer) Commit(pkt []byte) error {
-	if c.gsoW == nil {
-		c.addPassthrough(pkt)
-		return nil
-	}
-	info, ok := parseUDP(pkt)
-	if !ok {
-		c.addPassthrough(pkt)
-		return nil
-	}
-	return c.commitParsed(pkt, info)
-}
-
-// commitParsed is the post-parse half of Commit. The caller must have
-// already verified parseUDP succeeded. Used by MultiCoalescer.Commit to
-// avoid re-walking the IP/UDP header.
-func (c *UDPCoalescer) commitParsed(pkt []byte, info parsedUDP) error {
-	if c.gsoW == nil {
-		c.addPassthrough(pkt)
-		return nil
-	}
-	if open := c.openSlots[info.fk]; open != nil {
-		if c.canAppend(open, pkt, info) {
-			c.appendPayload(open, pkt, info)
-			if open.sealed {
-				delete(c.openSlots, info.fk)
-			}
-			return nil
-		}
-		// Can't extend — seal it and fall through to seed a fresh slot.
-		delete(c.openSlots, info.fk)
-	}
-	c.seed(pkt, info)
-	return nil
-}
-
-func (c *UDPCoalescer) Flush() error {
-	var first error
-	for _, s := range c.slots {
-		var err error
-		if s.passthrough {
-			_, err = c.plainW.Write(s.rawPkt)
-		} else {
-			err = c.flushSlot(s)
-		}
-		if err != nil && first == nil {
-			first = err
-		}
-		c.release(s)
-	}
-	clear(c.slots)
-	c.slots = c.slots[:0]
-	clear(c.openSlots)
-	c.backing = c.backing[:0]
-	return first
-}
-
-func (c *UDPCoalescer) addPassthrough(pkt []byte) {
-	s := c.take()
-	s.passthrough = true
-	s.rawPkt = pkt
-	c.slots = append(c.slots, s)
-}
-
-func (c *UDPCoalescer) seed(pkt []byte, info parsedUDP) {
-	if info.hdrLen > udpCoalesceHdrCap || info.hdrLen+info.payLen > udpCoalesceBufSize {
-		c.addPassthrough(pkt)
-		return
-	}
-	s := c.take()
-	s.passthrough = false
-	s.rawPkt = nil
-	copy(s.hdrBuf[:], pkt[:info.hdrLen])
-	s.hdrLen = info.hdrLen
-	s.ipHdrLen = info.ipHdrLen
-	s.isV6 = info.fk.isV6
-	s.fk = info.fk
-	s.gsoSize = info.payLen
-	s.numSeg = 1
-	s.totalPay = info.payLen
-	s.sealed = false
-	s.payIovs = append(s.payIovs[:0], pkt[info.hdrLen:info.hdrLen+info.payLen])
-	c.slots = append(c.slots, s)
-	c.openSlots[info.fk] = s
-}
-
-// canAppend reports whether info's packet extends the slot's seed.
-// Kernel UDP-GSO requires every segment except possibly the last to be
-// exactly gsoSize, and the last may be shorter (≤ gsoSize).
-func (c *UDPCoalescer) canAppend(s *udpSlot, pkt []byte, info parsedUDP) bool {
-	if s.sealed {
-		return false
-	}
-	if info.hdrLen != s.hdrLen {
-		return false
-	}
-	if s.numSeg >= udpCoalesceMaxSegs {
-		return false
-	}
-	if info.payLen > s.gsoSize {
-		return false
-	}
-	if s.hdrLen+s.totalPay+info.payLen > udpCoalesceBufSize {
-		return false
-	}
-	if !udpHeadersMatch(s.hdrBuf[:s.hdrLen], pkt[:info.hdrLen], s.isV6, s.ipHdrLen) {
-		return false
-	}
-	return true
-}
-
-func (c *UDPCoalescer) appendPayload(s *udpSlot, pkt []byte, info parsedUDP) {
-	s.payIovs = append(s.payIovs, pkt[info.hdrLen:info.hdrLen+info.payLen])
-	s.numSeg++
-	s.totalPay += info.payLen
-	// Merge IP-level CE marks into the seed (same trick TCP coalescer uses).
-	mergeECNIntoSeed(s.hdrBuf[:s.ipHdrLen], pkt[:s.ipHdrLen], s.isV6)
-	if info.payLen < s.gsoSize {
-		// Last-segment-can-be-shorter: this seals the chain.
-		s.sealed = true
-	}
-}
-
-func (c *UDPCoalescer) take() *udpSlot {
-	if n := len(c.pool); n > 0 {
-		s := c.pool[n-1]
-		c.pool[n-1] = nil
-		c.pool = c.pool[:n-1]
-		return s
-	}
-	return &udpSlot{}
-}
-
-func (c *UDPCoalescer) release(s *udpSlot) {
-	s.passthrough = false
-	s.rawPkt = nil
-	clear(s.payIovs)
-	s.payIovs = s.payIovs[:0]
-	s.numSeg = 0
-	s.totalPay = 0
-	s.sealed = false
-	c.pool = append(c.pool, s)
-}
-
-// flushSlot patches the IP header total length / IPv6 payload length and
-// the UDP length to the *total* across all coalesced segments, then seeds
-// the UDP checksum field with the pseudo-header partial (single-fold, not
-// inverted) per virtio NEEDS_CSUM. The kernel's ip_rcv_core (v4) and
-// ip6_rcv_core (v6) trim the skb to those length fields, so per-segment
-// values would silently drop everything but the first segment. The kernel
-// then walks each segment in __udp_gso_segment, recomputing per-segment
-// uh->len / iph->tot_len / IPv6 plen and adjusting the checksum via
-// `check = csum16_add(csum16_sub(uh->check, uh->len), newlen)` — meaning
-// our seed's uh->check must be consistent with the seed's uh->len, which
-// is what passing the total to both pseudoSum and the UDP length field
-// guarantees.
-func (c *UDPCoalescer) flushSlot(s *udpSlot) error {
-	hdr := s.hdrBuf[:s.hdrLen]
-	total := s.hdrLen + s.totalPay // full IP+UDP+all_payloads bytes
-	l4Len := total - s.ipHdrLen    // total UDP (8 + sum of payloads)
-
-	if s.isV6 {
-		binary.BigEndian.PutUint16(hdr[4:6], uint16(l4Len))
-	} else {
-		binary.BigEndian.PutUint16(hdr[2:4], uint16(total))
-		hdr[10] = 0
-		hdr[11] = 0
-		binary.BigEndian.PutUint16(hdr[10:12], ipv4HdrChecksum(hdr[:s.ipHdrLen]))
-	}
-
-	// UDP length field (offset 4 inside the UDP header) = total UDP size.
-	binary.BigEndian.PutUint16(hdr[s.ipHdrLen+4:s.ipHdrLen+6], uint16(l4Len))
-
-	var psum uint32
-	if s.isV6 {
-		psum = pseudoSumIPv6(hdr[8:24], hdr[24:40], ipProtoUDP, l4Len)
-	} else {
-		psum = pseudoSumIPv4(hdr[12:16], hdr[16:20], ipProtoUDP, l4Len)
-	}
-	udpCsumOff := s.ipHdrLen + 6
-	binary.BigEndian.PutUint16(hdr[udpCsumOff:udpCsumOff+2], foldOnceNoInvert(psum))
-
-	return c.gsoW.WriteGSO(hdr[:s.ipHdrLen], hdr[s.ipHdrLen:], s.payIovs, tio.GSOProtoUDP)
-}
-
-// udpHeadersMatch compares two IP+UDP header prefixes for byte-equality on
-// every field that must be identical across coalesced segments. Length
-// fields and the ECN bits in IP TOS/TC are masked out — appendPayload
-// merges CE into the seed; flushSlot rewrites lengths.
-func udpHeadersMatch(a, b []byte, isV6 bool, ipHdrLen int) bool {
-	if len(a) != len(b) {
-		return false
-	}
-	if !ipHeadersMatch(a, b, isV6) {
-		return false
-	}
-	// UDP: compare sport+dport ([0:4]). Skip length [4:6] and checksum [6:8] —
-	// length varies (we rewrite at flush) and the checksum will be redone.
-	udp := ipHdrLen
-	if a[udp] != b[udp] || a[udp+1] != b[udp+1] || a[udp+2] != b[udp+2] || a[udp+3] != b[udp+3] {
-		return false
-	}
-	return true
-}

overlay/batch/udp_coalesce_test.go

@@ -1,383 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"testing"
-)
-
-// buildUDPv4 builds a minimal IPv4+UDP packet with the given payload and ports.
-func buildUDPv4(sport, dport uint16, payload []byte) []byte {
-	const ipHdrLen = 20
-	const udpHdrLen = 8
-	total := ipHdrLen + udpHdrLen + len(payload)
-	pkt := make([]byte, total)
-
-	pkt[0] = 0x45
-	pkt[1] = 0x00
-	binary.BigEndian.PutUint16(pkt[2:4], uint16(total))
-	binary.BigEndian.PutUint16(pkt[4:6], 0)
-	binary.BigEndian.PutUint16(pkt[6:8], 0x4000)
-	pkt[8] = 64
-	pkt[9] = ipProtoUDP
-	copy(pkt[12:16], []byte{10, 0, 0, 1})
-	copy(pkt[16:20], []byte{10, 0, 0, 2})
-
-	binary.BigEndian.PutUint16(pkt[20:22], sport)
-	binary.BigEndian.PutUint16(pkt[22:24], dport)
-	binary.BigEndian.PutUint16(pkt[24:26], uint16(udpHdrLen+len(payload)))
-	binary.BigEndian.PutUint16(pkt[26:28], 0)
-
-	copy(pkt[28:], payload)
-	return pkt
-}
-
-// buildUDPv6 builds a minimal IPv6+UDP packet.
-func buildUDPv6(sport, dport uint16, payload []byte) []byte {
-	const ipHdrLen = 40
-	const udpHdrLen = 8
-	total := ipHdrLen + udpHdrLen + len(payload)
-	pkt := make([]byte, total)
-
-	pkt[0] = 0x60
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(udpHdrLen+len(payload)))
-	pkt[6] = ipProtoUDP
-	pkt[7] = 64
-	pkt[8] = 0xfe
-	pkt[9] = 0x80
-	pkt[23] = 1
-	pkt[24] = 0xfe
-	pkt[25] = 0x80
-	pkt[39] = 2
-
-	binary.BigEndian.PutUint16(pkt[40:42], sport)
-	binary.BigEndian.PutUint16(pkt[42:44], dport)
-	binary.BigEndian.PutUint16(pkt[44:46], uint16(udpHdrLen+len(payload)))
-	binary.BigEndian.PutUint16(pkt[46:48], 0)
-
-	copy(pkt[48:], payload)
-	return pkt
-}
-
-func TestUDPCoalescerPassthroughWhenGSOUnavailable(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: false}
-	c := NewUDPCoalescer(w)
-	pkt := buildUDPv4(1000, 53, make([]byte, 100))
-	if err := c.Commit(pkt); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 0 || len(w.gsoWrites) != 0 {
-		t.Fatalf("no Add-time writes: writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 1 || len(w.gsoWrites) != 0 {
-		t.Fatalf("want single plain write, got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-}
-
-func TestUDPCoalescerNonUDPPassthrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	// ICMP packet
-	pkt := make([]byte, 28)
-	pkt[0] = 0x45
-	binary.BigEndian.PutUint16(pkt[2:4], 28)
-	pkt[9] = 1
-	copy(pkt[12:16], []byte{10, 0, 0, 1})
-	copy(pkt[16:20], []byte{10, 0, 0, 2})
-	if err := c.Commit(pkt); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 1 || len(w.gsoWrites) != 0 {
-		t.Fatalf("ICMP must pass through unchanged: writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-}
-
-func TestUDPCoalescerSeedThenFlushAlone(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pkt := buildUDPv4(1000, 53, make([]byte, 800))
-	if err := c.Commit(pkt); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	// Single-segment flush goes through WriteGSO; the writer infers GSO_NONE
-	// from len(pays)==1 and the kernel fills in the UDP csum (NEEDS_CSUM).
-	if len(w.gsoWrites) != 1 || len(w.writes) != 0 {
-		t.Fatalf("single-seg flush: writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-}
-
-func TestUDPCoalescerCoalescesEqualSized(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pay := make([]byte, 1200)
-	for i := 0; i < 3; i++ {
-		if err := c.Commit(buildUDPv4(1000, 53, pay)); err != nil {
-			t.Fatal(err)
-		}
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 1 {
-		t.Fatalf("want 1 gso write, got %d (plain=%d)", len(w.gsoWrites), len(w.writes))
-	}
-	g := w.gsoWrites[0]
-	if g.gsoSize != 1200 {
-		t.Errorf("gsoSize=%d want 1200", g.gsoSize)
-	}
-	if len(g.pays) != 3 {
-		t.Errorf("pay count=%d want 3", len(g.pays))
-	}
-	if g.csumStart != 20 {
-		t.Errorf("csumStart=%d want 20", g.csumStart)
-	}
-	// IP totalLen and UDP length must be the TOTAL across all segments —
-	// the kernel's ip_rcv_core trims skbs to iph->tot_len, so a per-segment
-	// value would silently drop everything but the first segment. Total =
-	// IP(20) + UDP(8) + 3*1200 = 3628.
-	gotTotalLen := binary.BigEndian.Uint16(g.hdr[2:4])
-	if gotTotalLen != 3628 {
-		t.Errorf("ipv4 total_len=%d want 3628 (must be total across segments)", gotTotalLen)
-	}
-	gotUDPLen := binary.BigEndian.Uint16(g.hdr[20+4 : 20+6])
-	if gotUDPLen != 8+3*1200 {
-		t.Errorf("udp len=%d want %d", gotUDPLen, 8+3*1200)
-	}
-}
-
-// Last segment may be shorter, sealing the chain.
-func TestUDPCoalescerShortLastSegmentSeals(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	full := make([]byte, 1200)
-	tail := make([]byte, 600)
-	if err := c.Commit(buildUDPv4(1000, 53, full)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(1000, 53, full)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(1000, 53, tail)); err != nil {
-		t.Fatal(err)
-	}
-	// A 4th packet, even same-sized, must NOT join — chain is sealed.
-	if err := c.Commit(buildUDPv4(1000, 53, full)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 gso writes (sealed + new seed), got %d", len(w.gsoWrites))
-	}
-	if len(w.gsoWrites[0].pays) != 3 {
-		t.Errorf("first super: want 3 pays, got %d", len(w.gsoWrites[0].pays))
-	}
-	if len(w.gsoWrites[1].pays) != 1 {
-		t.Errorf("second super: want 1 pay (re-seed), got %d", len(w.gsoWrites[1].pays))
-	}
-}
-
-// A larger-than-gsoSize packet cannot extend the slot — it reseeds.
-func TestUDPCoalescerLargerThanSeedReseeds(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	if err := c.Commit(buildUDPv4(1000, 53, make([]byte, 800))); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(1000, 53, make([]byte, 1200))); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 separate seeds, got %d", len(w.gsoWrites))
-	}
-}
-
-// Different 5-tuples must not coalesce.
-func TestUDPCoalescerDifferentFlowsKeepSeparate(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pay := make([]byte, 800)
-	if err := c.Commit(buildUDPv4(1000, 53, pay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(2000, 53, pay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(1000, 53, pay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(2000, 53, pay)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	// Two flows × 2 datagrams each = 2 superpackets of 2 segments.
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 gso writes (one per flow), got %d", len(w.gsoWrites))
-	}
-	for i, g := range w.gsoWrites {
-		if len(g.pays) != 2 {
-			t.Errorf("super %d: want 2 pays, got %d", i, len(g.pays))
-		}
-	}
-}
-
-// Caps at udpCoalesceMaxSegs.
-func TestUDPCoalescerCapsAtMaxSegs(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pay := make([]byte, 100)
-	for i := 0; i < udpCoalesceMaxSegs+5; i++ {
-		if err := c.Commit(buildUDPv4(1000, 53, pay)); err != nil {
-			t.Fatal(err)
-		}
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	// First superpacket holds udpCoalesceMaxSegs segments; the spillover
-	// reseeds a new one.
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 gso writes (cap then reseed), got %d", len(w.gsoWrites))
-	}
-	if len(w.gsoWrites[0].pays) != udpCoalesceMaxSegs {
-		t.Errorf("first super: pays=%d want %d", len(w.gsoWrites[0].pays), udpCoalesceMaxSegs)
-	}
-	if len(w.gsoWrites[1].pays) != 5 {
-		t.Errorf("second super: pays=%d want 5", len(w.gsoWrites[1].pays))
-	}
-}
-
-// CE marks on appended segments must be merged into the seed's IP TOS.
-func TestUDPCoalescerMergesCEMark(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pay := make([]byte, 800)
-	pkt0 := buildUDPv4(1000, 53, pay) // ECN=00
-	pkt1 := buildUDPv4(1000, 53, pay)
-	pkt1[1] = 0x03 // CE
-	pkt2 := buildUDPv4(1000, 53, pay)
-	if err := c.Commit(pkt0); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(pkt1); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(pkt2); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 1 {
-		t.Fatalf("want 1 merged gso write, got %d (plain=%d)", len(w.gsoWrites), len(w.writes))
-	}
-	if w.gsoWrites[0].hdr[1]&0x03 != 0x03 {
-		t.Errorf("CE not merged into seed (tos=%#x)", w.gsoWrites[0].hdr[1])
-	}
-}
-
-// IPv6 path: same flow, equal-sized → coalesced.
-func TestUDPCoalescerIPv6Coalesces(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pay := make([]byte, 1200)
-	for i := 0; i < 3; i++ {
-		if err := c.Commit(buildUDPv6(1000, 53, pay)); err != nil {
-			t.Fatal(err)
-		}
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 1 {
-		t.Fatalf("want 1 gso write, got %d", len(w.gsoWrites))
-	}
-	g := w.gsoWrites[0]
-	if !g.isV6 {
-		t.Errorf("expected v6 write")
-	}
-	if g.csumStart != 40 {
-		t.Errorf("csumStart=%d want 40", g.csumStart)
-	}
-	// IPv6 payload_len and UDP length must be TOTAL — kernel's
-	// ip6_rcv_core trims to payload_len + ipv6 hdr size. Total UDP = 8 +
-	// 3*1200 = 3608.
-	gotPlen := binary.BigEndian.Uint16(g.hdr[4:6])
-	if gotPlen != 8+3*1200 {
-		t.Errorf("ipv6 payload_len=%d want %d (must be total)", gotPlen, 8+3*1200)
-	}
-	gotUDPLen := binary.BigEndian.Uint16(g.hdr[40+4 : 40+6])
-	if gotUDPLen != 8+3*1200 {
-		t.Errorf("udp len=%d want %d", gotUDPLen, 8+3*1200)
-	}
-}
-
-// DSCP differences must reseed (headers don't match outside ECN).
-func TestUDPCoalescerDSCPMismatchReseeds(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pay := make([]byte, 800)
-	pkt0 := buildUDPv4(1000, 53, pay)
-	pkt1 := buildUDPv4(1000, 53, pay)
-	pkt1[1] = 0xb8 // EF DSCP, ECN=0
-	if err := c.Commit(pkt0); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(pkt1); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 separate seeds (different DSCP), got %d", len(w.gsoWrites))
-	}
-}
-
-// Fragmented IPv4 must not be coalesced.
-func TestUDPCoalescerFragmentedIPv4PassesThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pkt := buildUDPv4(1000, 53, make([]byte, 200))
-	binary.BigEndian.PutUint16(pkt[6:8], 0x2000) // MF=1
-	if err := c.Commit(pkt); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 1 || len(w.gsoWrites) != 0 {
-		t.Fatalf("frag must pass through plain, got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-}
-
-// IPv4 with options is not admissible (we require IHL=5).
-func TestUDPCoalescerIPv4WithOptionsPassesThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewUDPCoalescer(w)
-	pkt := buildUDPv4(1000, 53, make([]byte, 200))
-	pkt[0] = 0x46 // IHL = 6 (24-byte IPv4 header — has options)
-	if err := c.Commit(pkt); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 1 || len(w.gsoWrites) != 0 {
-		t.Fatalf("ipv4-with-options must pass through plain, got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-}

overlay/checksum/checksum_amd64.go

@@ -1,23 +0,0 @@
-package checksum
-
-import (
-	"golang.org/x/sys/cpu"
-	gvisorchecksum "gvisor.dev/gvisor/pkg/tcpip/checksum"
-)
-
-//go:noescape
-func checksumAVX2(buf []byte, initial uint16) uint16
-
-var hasAVX2 = cpu.X86.HasAVX2
-
-// Checksum computes the RFC 1071 ones-complement sum of buf, seeded with
-// initial. It is a drop-in replacement for gvisor's checksum.Checksum that
-// dispatches to a hand-written AVX2 routine on amd64 CPUs that support it,
-// falling back to gvisor's pure-Go implementation otherwise. The result
-// matches gvisor's bit-for-bit for any buffer length and initial seed.
-func Checksum(buf []byte, initial uint16) uint16 {
-	if hasAVX2 {
-		return checksumAVX2(buf, initial)
-	}
-	return gvisorchecksum.Checksum(buf, initial)
-}

overlay/checksum/checksum_amd64.s

@@ -1,157 +0,0 @@
-#include "textflag.h"
-
-// func checksumAVX2(buf []byte, initial uint16) uint16
-//
-// Computes the RFC 1071 ones-complement sum of buf, seeded with initial.
-//
-// Algorithm: sum the buffer treating it as a stream of uint32s in machine
-// (little-endian) byte order, accumulating into 64-bit lanes (top 32 bits
-// hold cross-add carries — at 1 byte / lane / iter we have 32 bits of
-// headroom which is far more than the 16 KB/64 KB max practical inputs).
-// At the end we fold to 16 bits and byte-swap once to recover the on-wire
-// (big-endian) result. RFC 1071 §1.2.B byte-order independence makes this
-// equivalent to summing as 16-bit big-endian words.
-//
-// The ymm accumulators (Y4..Y7) hold 4 uint64 lanes each = 16 parallel
-// partial sums. The main loop loads 64 bytes per iter as four 16-byte
-// chunks, zero-extending each chunk's four uint32s into a ymm via
-// VPMOVZXDQ-from-memory, then VPADDQ into a separate accumulator per
-// chunk to break the dep chain. After the vector loop the lane sums are
-// horizontally reduced and merged with a scalar accumulator that handles
-// the trailing 0..63 bytes plus the (byte-swapped) initial seed.
-TEXT ·checksumAVX2(SB), NOSPLIT, $0-34
-	MOVQ    buf_base+0(FP), SI
-	MOVQ    buf_len+8(FP), CX
-	MOVWQZX initial+24(FP), AX
-
-	// Pre-byteswap initial into the LE-summing space so it merges directly
-	// with the rest of the accumulator. The final fold's bswap16 will undo
-	// this and convert the whole result back to BE.
-	XCHGB AH, AL
-
-	CMPQ CX, $32
-	JLT  scalar_tail
-
-	VPXOR Y4, Y4, Y4
-	VPXOR Y5, Y5, Y5
-	VPXOR Y6, Y6, Y6
-	VPXOR Y7, Y7, Y7
-
-	CMPQ CX, $64
-	JLT  loop32
-
-loop64:
-	VPMOVZXDQ (SI), Y0
-	VPMOVZXDQ 16(SI), Y1
-	VPMOVZXDQ 32(SI), Y2
-	VPMOVZXDQ 48(SI), Y3
-	VPADDQ    Y0, Y4, Y4
-	VPADDQ    Y1, Y5, Y5
-	VPADDQ    Y2, Y6, Y6
-	VPADDQ    Y3, Y7, Y7
-	ADDQ      $64, SI
-	SUBQ      $64, CX
-	CMPQ      CX, $64
-	JGE       loop64
-
-loop32:
-	CMPQ      CX, $32
-	JLT       reduce_vec
-	VPMOVZXDQ (SI), Y0
-	VPMOVZXDQ 16(SI), Y1
-	VPADDQ    Y0, Y4, Y4
-	VPADDQ    Y1, Y5, Y5
-	ADDQ      $32, SI
-	SUBQ      $32, CX
-	JMP       loop32
-
-reduce_vec:
-	// Combine the four ymm accumulators into Y4.
-	VPADDQ Y5, Y4, Y4
-	VPADDQ Y7, Y6, Y6
-	VPADDQ Y6, Y4, Y4
-
-	// Horizontally reduce Y4's four uint64 lanes to a single scalar.
-	VEXTRACTI128 $1, Y4, X5
-	VPADDQ       X5, X4, X4
-	VPSHUFD      $0x4e, X4, X5
-	VPADDQ       X5, X4, X4
-	VMOVQ        X4, R8
-	VZEROUPPER
-
-	ADDQ R8, AX
-	ADCQ $0, AX
-
-scalar_tail:
-	// Handle remaining 0..63 bytes (or the entire buffer if it was < 32).
-	CMPQ CX, $8
-	JLT  tail4
-
-loop8:
-	ADDQ (SI), AX
-	ADCQ $0, AX
-	ADDQ $8, SI
-	SUBQ $8, CX
-	CMPQ CX, $8
-	JGE  loop8
-
-tail4:
-	CMPQ CX, $4
-	JLT  tail2
-	MOVL (SI), R8
-	ADDQ R8, AX
-	ADCQ $0, AX
-	ADDQ $4, SI
-	SUBQ $4, CX
-
-tail2:
-	CMPQ    CX, $2
-	JLT     tail1
-	MOVWQZX (SI), R8
-	ADDQ    R8, AX
-	ADCQ    $0, AX
-	ADDQ    $2, SI
-	SUBQ    $2, CX
-
-tail1:
-	TESTQ   CX, CX
-	JZ      fold
-	MOVBQZX (SI), R8
-	ADDQ    R8, AX
-	ADCQ    $0, AX
-
-fold:
-	// Fold the 64-bit accumulator to 16 bits via four rounds, mirroring
-	// gvisor's reduce(). Each pair (split, add) halves the live width;
-	// the truncation steps absorb the single bit that may be left over
-	// after each add so the next round's bound holds.
-
-	// 64 → 33 bits.
-	MOVQ AX, R8
-	SHRQ $32, R8
-	MOVL AX, AX
-	ADDQ R8, AX
-
-	// 33 → 32 bits. AX += (AX>>32); truncate to 32. AX is now ≤ 0xFFFF_FFFF.
-	MOVQ AX, R8
-	SHRQ $32, R8
-	ADDQ R8, AX
-	MOVL AX, AX
-
-	// 32 → 17 bits.
-	MOVQ    AX, R8
-	SHRQ    $16, R8
-	MOVWQZX AX, AX
-	ADDQ    R8, AX
-
-	// 17 → 16 bits. AX += (AX>>16); the trailing MOVW truncates bit 16.
-	MOVQ AX, R8
-	SHRQ $16, R8
-	ADDQ R8, AX
-
-	// AX low 16 bits hold the 16-bit sum in machine (LE) byte order; flip
-	// to big-endian to match the gvisor API contract.
-	XCHGB AH, AL
-
-	MOVW AX, ret+32(FP)
-	RET

overlay/checksum/checksum_arm64.go

@@ -1,12 +0,0 @@
-package checksum
-
-//go:noescape
-func checksumNEON(buf []byte, initial uint16) uint16
-
-// Checksum computes the RFC 1071 ones-complement sum of buf, seeded with
-// initial. It is a drop-in replacement for gvisor's checksum.Checksum
-// that dispatches to a hand-written NEON routine. NEON is mandatory in
-// armv8 so no feature check is needed.
-func Checksum(buf []byte, initial uint16) uint16 {
-	return checksumNEON(buf, initial)
-}

overlay/checksum/checksum_arm64.s

@@ -1,143 +0,0 @@
-#include "textflag.h"
-
-// func checksumNEON(buf []byte, initial uint16) uint16
-//
-// Mirrors the algorithm in checksum_amd64.s: sum the buffer treating it as
-// a stream of uint32s in machine (little-endian) byte order, accumulating
-// into 64-bit lanes that have ample carry headroom; fold and byte-swap once
-// at the very end to recover the on-wire (big-endian) result.
-//
-// Each loop iteration loads 64 bytes via VLD1.P into V0..V3 (4 Q regs).
-// VUADDW takes the low two uint32 lanes of a Q reg, zero-extends them to
-// uint64, and adds them into a 2×uint64 accumulator; VUADDW2 does the same
-// for the high two lanes. Four ymm-equivalent accumulators (V8..V11) get
-// updated twice per iter to break the dep chain. Tail bytes go through a
-// scalar ADCS chain seeded with the byte-swapped initial.
-TEXT ·checksumNEON(SB), NOSPLIT, $0-34
-	MOVD  buf_base+0(FP), R0
-	MOVD  buf_len+8(FP), R1
-	MOVHU initial+24(FP), R2
-
-	// Pre-byteswap initial into the LE-summing space so it merges directly
-	// with the rest of the accumulator.
-	REV16W R2, R2
-
-	MOVD ZR, R3 // scalar accumulator
-
-	CMP $32, R1
-	BLT scalar_tail
-
-	VEOR V8.B16, V8.B16, V8.B16
-	VEOR V9.B16, V9.B16, V9.B16
-	VEOR V10.B16, V10.B16, V10.B16
-	VEOR V11.B16, V11.B16, V11.B16
-
-	CMP $64, R1
-	BLT loop16_init
-
-loop64:
-	VLD1.P  64(R0), [V0.B16, V1.B16, V2.B16, V3.B16]
-	VUADDW  V0.S2, V8.D2, V8.D2
-	VUADDW2 V0.S4, V9.D2, V9.D2
-	VUADDW  V1.S2, V10.D2, V10.D2
-	VUADDW2 V1.S4, V11.D2, V11.D2
-	VUADDW  V2.S2, V8.D2, V8.D2
-	VUADDW2 V2.S4, V9.D2, V9.D2
-	VUADDW  V3.S2, V10.D2, V10.D2
-	VUADDW2 V3.S4, V11.D2, V11.D2
-	SUB     $64, R1, R1
-	CMP     $64, R1
-	BGE     loop64
-
-loop16_init:
-	CMP $16, R1
-	BLT reduce_vec
-
-loop16:
-	VLD1.P  16(R0), [V0.B16]
-	VUADDW  V0.S2, V8.D2, V8.D2
-	VUADDW2 V0.S4, V9.D2, V9.D2
-	SUB     $16, R1, R1
-	CMP     $16, R1
-	BGE     loop16
-
-reduce_vec:
-	// Combine the four accumulators into V8.
-	VADD V9.D2, V8.D2, V8.D2
-	VADD V11.D2, V10.D2, V10.D2
-	VADD V10.D2, V8.D2, V8.D2
-
-	// Horizontal-add the two lanes of V8.D2 into a single uint64.
-	VADDP V8.D2, V8.D2, V8.D2
-	VMOV  V8.D[0], R8
-
-	ADDS R8, R3, R3
-	ADC  ZR, R3, R3
-
-scalar_tail:
-	CMP $8, R1
-	BLT tail4
-
-loop8:
-	MOVD.P 8(R0), R8
-	ADDS   R8, R3, R3
-	ADC    ZR, R3, R3
-	SUB    $8, R1, R1
-	CMP    $8, R1
-	BGE    loop8
-
-tail4:
-	CMP    $4, R1
-	BLT    tail2
-	MOVWU.P 4(R0), R8
-	ADDS   R8, R3, R3
-	ADC    ZR, R3, R3
-	SUB    $4, R1, R1
-
-tail2:
-	CMP    $2, R1
-	BLT    tail1
-	MOVHU.P 2(R0), R8
-	ADDS   R8, R3, R3
-	ADC    ZR, R3, R3
-	SUB    $2, R1, R1
-
-tail1:
-	CBZ R1, fold
-	MOVBU (R0), R8
-	ADDS  R8, R3, R3
-	ADC   ZR, R3, R3
-
-fold:
-	// Merge the byte-swapped initial into our LE-form accumulator.
-	ADDS R2, R3, R3
-	ADC  ZR, R3, R3
-
-	// 64 → 33 bits.
-	LSR $32, R3, R8
-	AND $0xffffffff, R3, R3
-	ADD R8, R3, R3
-
-	// 33 → 32 (truncate after adding bit 32 back).
-	LSR $32, R3, R8
-	ADD R8, R3, R3
-	AND $0xffffffff, R3, R3
-
-	// 32 → 17.
-	LSR $16, R3, R8
-	AND $0xffff, R3, R3
-	ADD R8, R3, R3
-
-	// 17 → 16 (truncation absorbs bit 16 below).
-	LSR $16, R3, R8
-	ADD R8, R3, R3
-
-	// AX low 16 bits hold the 16-bit sum in machine (LE) byte order; flip
-	// to big-endian to match the gvisor API contract. REV16W swaps bytes
-	// within each 16-bit halfword of the low 32 bits, so it acts as a
-	// 16-bit byte-swap on the live low 16.
-	REV16W R3, R3
-	AND    $0xffff, R3, R3
-
-	MOVH R3, ret+32(FP)
-	RET

overlay/checksum/checksum_fallback.go

@@ -1,10 +0,0 @@
-//go:build !amd64 && !arm64
-
-package checksum
-
-import gvisorchecksum "gvisor.dev/gvisor/pkg/tcpip/checksum"
-
-// Checksum delegates to gvisor on architectures without a hand-written body.
-func Checksum(buf []byte, initial uint16) uint16 {
-	return gvisorchecksum.Checksum(buf, initial)
-}

overlay/checksum/checksum_test.go

@@ -1,190 +0,0 @@
-package checksum
-
-import (
-	"fmt"
-	"math/rand/v2"
-	"testing"
-
-	gvisorchecksum "gvisor.dev/gvisor/pkg/tcpip/checksum"
-)
-
-// TestChecksumMatchesGvisor walks lengths from 0 to 4096, with several initial
-// seeds and a handful of starting alignments, asserting that our local
-// Checksum matches gvisor's reference bit-for-bit.
-func TestChecksumMatchesGvisor(t *testing.T) {
-	rng := rand.New(rand.NewPCG(1, 2))
-	const padFront = 16
-
-	// Random pool large enough for the longest case + alignment slop.
-	pool := make([]byte, 4096+padFront)
-	for i := range pool {
-		pool[i] = byte(rng.Uint32())
-	}
-
-	seeds := []uint16{0, 0x0001, 0xabcd, 0xffff, 0x1234, 0xfedc}
-	offsets := []int{0, 1, 2, 3, 4, 5, 7, 8, 15, 16}
-
-	for length := 0; length <= 4096; length++ {
-		for _, seed := range seeds {
-			for _, off := range offsets {
-				if off+length > len(pool) {
-					continue
-				}
-				buf := pool[off : off+length]
-				want := gvisorchecksum.Checksum(buf, seed)
-				got := Checksum(buf, seed)
-				if got != want {
-					t.Fatalf("len=%d off=%d seed=%#x: got %#04x want %#04x",
-						length, off, seed, got, want)
-				}
-			}
-		}
-	}
-}
-
-// TestChecksumPatternedBuffers exercises specific byte patterns that have
-// historically tripped up checksum implementations: all-zero, all-0xff,
-// alternating, and ascending sequences.
-func TestChecksumPatternedBuffers(t *testing.T) {
-	for length := 0; length <= 256; length++ {
-		patterns := map[string][]byte{
-			"zeros":       make([]byte, length),
-			"ones":        bytes(length, 0xff),
-			"alternating": pattern(length, []byte{0xa5, 0x5a}),
-			"ascending":   ascending(length),
-		}
-		for name, buf := range patterns {
-			for _, seed := range []uint16{0, 0xffff, 0x8000} {
-				want := gvisorchecksum.Checksum(buf, seed)
-				got := Checksum(buf, seed)
-				if got != want {
-					t.Fatalf("%s len=%d seed=%#x: got %#04x want %#04x",
-						name, length, seed, got, want)
-				}
-			}
-		}
-	}
-}
-
-func bytes(n int, v byte) []byte {
-	b := make([]byte, n)
-	for i := range b {
-		b[i] = v
-	}
-	return b
-}
-
-func pattern(n int, p []byte) []byte {
-	b := make([]byte, n)
-	for i := range b {
-		b[i] = p[i%len(p)]
-	}
-	return b
-}
-
-func ascending(n int) []byte {
-	b := make([]byte, n)
-	for i := range b {
-		b[i] = byte(i)
-	}
-	return b
-}
-
-// TestChecksumTailPaths targets every combination of (SIMD body iterations,
-// trailing tail bytes) the asm handlers walk through. The tail handlers
-// peel off 8 → 4 → 2 → 1 byte chunks in turn; this test exercises each by
-// constructing lengths of the form 64*k + tail for tail ∈ [0, 63] and a
-// representative spread of k values, including k=0 (no main loop, all tail)
-// and k=1 (one main loop iter, then tail). It's explicit coverage for
-// payload sizes that are odd, not divisible by 4, by 8, or by 32.
-func TestChecksumTailPaths(t *testing.T) {
-	rng := rand.New(rand.NewPCG(42, 17))
-	const padFront = 16
-	const maxK = 8
-
-	pool := make([]byte, 64*maxK+padFront+64)
-	for i := range pool {
-		pool[i] = byte(rng.Uint32())
-	}
-
-	seeds := []uint16{0, 0xffff, 0xabcd}
-	offsets := []int{0, 1, 3, 7, 15} // mix of aligned and odd starts
-
-	for k := 0; k <= maxK; k++ {
-		for tail := 0; tail < 64; tail++ {
-			length := 64*k + tail
-			for _, seed := range seeds {
-				for _, off := range offsets {
-					if off+length > len(pool) {
-						continue
-					}
-					buf := pool[off : off+length]
-					want := gvisorchecksum.Checksum(buf, seed)
-					got := Checksum(buf, seed)
-					if got != want {
-						t.Fatalf("k=%d tail=%d (len=%d) off=%d seed=%#x: got %#04x want %#04x",
-							k, tail, length, off, seed, got, want)
-					}
-				}
-			}
-		}
-	}
-}
-
-// BenchmarkChecksumTailSizes covers payload sizes that aren't clean multiples
-// of the SIMD body's 32-byte (amd64) or 16-byte (arm64) chunks, so the tail
-// handler is meaningfully on the hot path. Sizes are picked to either exercise
-// every tail branch (tiny lengths) or sit slightly off realistic packet
-// boundaries (e.g. 1499 = MTU − 1).
-func BenchmarkChecksumTailSizes(b *testing.B) {
-	sizes := []int{
-		1, 3, 7, 15, 31, // sub-SIMD; entire work is scalar tail
-		33, 35, 47, 63, // one loop32 + assorted tails
-		65, 95, 127, // one loop64 + assorted tails
-		1447, 1471, 1499, 1501, // around MTU
-		8191, 8193, // around USO
-		65531, 65533, // near the kernel max
-	}
-	for _, size := range sizes {
-		buf := make([]byte, size)
-		for i := range buf {
-			buf[i] = byte(i)
-		}
-		b.Run(fmt.Sprintf("size=%d/local", size), func(b *testing.B) {
-			b.SetBytes(int64(size))
-			for i := 0; i < b.N; i++ {
-				_ = Checksum(buf, 0)
-			}
-		})
-		b.Run(fmt.Sprintf("size=%d/gvisor", size), func(b *testing.B) {
-			b.SetBytes(int64(size))
-			for i := 0; i < b.N; i++ {
-				_ = gvisorchecksum.Checksum(buf, 0)
-			}
-		})
-	}
-}
-
-// BenchmarkChecksum compares the local Checksum to gvisor's at sizes that
-// match real traffic: a TCP/IP header (60), a typical MSS (1448), a typical
-// USO size (8192), and the kernel's max GSO superpacket (65535).
-func BenchmarkChecksum(b *testing.B) {
-	for _, size := range []int{60, 1448, 8192, 65535} {
-		buf := make([]byte, size)
-		for i := range buf {
-			buf[i] = byte(i)
-		}
-		b.Run(fmt.Sprintf("size=%d/local", size), func(b *testing.B) {
-			b.SetBytes(int64(size))
-			for i := 0; i < b.N; i++ {
-				_ = Checksum(buf, 0)
-			}
-		})
-		b.Run(fmt.Sprintf("size=%d/gvisor", size), func(b *testing.B) {
-			b.SetBytes(int64(size))
-			for i := 0; i < b.N; i++ {
-				_ = gvisorchecksum.Checksum(buf, 0)
-			}
-		})
-	}
-}

overlay/device.go

@@ -4,21 +4,18 @@ import (
 	"io"
 	"net/netip"
 
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 )
 
-// defaultBatchBufSize is the per-Queue scratch size for Read on backends
-// that don't do TSO segmentation. 65535 covers any single IP packet.
-const defaultBatchBufSize = 65535
-
 type Device interface {
-	io.Closer
+	io.ReadWriteCloser
 	Activate() error
 	Networks() []netip.Prefix
 	Name() string
 	RoutesFor(netip.Addr) routing.Gateways
 	SupportsMultiqueue() bool
-	NewMultiQueueReader() error
-	Readers() []tio.Queue
+	NewMultiQueueReader() (io.ReadWriteCloser, error)
+	// TunPrefixLen reports the number of bytes the device prepends to every IP packet on the wire.
+	// Currently only non zero for the BSD tun devices.
+	TunPrefixLen() int
 }

overlay/network_category_windows.go

@@ -1,358 +0,0 @@
-//go:build !e2e_testing
-// +build !e2e_testing
-
-package overlay
-
-import (
-	"errors"
-	"fmt"
-	"log/slog"
-	"runtime"
-	"strings"
-	"syscall"
-	"time"
-	"unsafe"
-
-	"golang.org/x/sys/windows"
-)
-
-// networkCategory mirrors NLM_NETWORK_CATEGORY from netlistmgr.h.
-type networkCategory int32
-
-const (
-	networkCategoryPublic              networkCategory = 0
-	networkCategoryPrivate             networkCategory = 1
-	networkCategoryDomainAuthenticated networkCategory = 2
-)
-
-func (c networkCategory) String() string {
-	switch c {
-	case networkCategoryPublic:
-		return "public"
-	case networkCategoryPrivate:
-		return "private"
-	case networkCategoryDomainAuthenticated:
-		return "domain"
-	}
-	return fmt.Sprintf("unknown(%d)", c)
-}
-
-// parseNetworkCategory accepts the user-supplied tun.network_category. A
-// second return of false means "leave the category alone".
-func parseNetworkCategory(s string) (networkCategory, bool, error) {
-	switch strings.ToLower(strings.TrimSpace(s)) {
-	case "", "unset":
-		return 0, false, nil
-	case "public":
-		return networkCategoryPublic, true, nil
-	case "private":
-		return networkCategoryPrivate, true, nil
-	case "domain", "domainauthenticated":
-		return networkCategoryDomainAuthenticated, true, nil
-	}
-	return 0, false, fmt.Errorf("unknown tun.network_category %q (expected public, private, domain, or unset)", s)
-}
-
-// CLSID_NetworkListManager {DCB00C01-570F-4A9B-8D69-199FDBA5723B}
-var clsidNetworkListManager = windows.GUID{
-	Data1: 0xDCB00C01, Data2: 0x570F, Data3: 0x4A9B,
-	Data4: [8]byte{0x8D, 0x69, 0x19, 0x9F, 0xDB, 0xA5, 0x72, 0x3B},
-}
-
-// IID_INetworkListManager {DCB00000-570F-4A9B-8D69-199FDBA5723B}
-var iidINetworkListManager = windows.GUID{
-	Data1: 0xDCB00000, Data2: 0x570F, Data3: 0x4A9B,
-	Data4: [8]byte{0x8D, 0x69, 0x19, 0x9F, 0xDB, 0xA5, 0x72, 0x3B},
-}
-
-// x/sys/windows doesn't expose CoCreateInstance, so we bind it ourselves.
-var procCoCreateInstance = windows.NewLazySystemDLL("ole32.dll").NewProc("CoCreateInstance")
-
-const clsCtxAll = windows.CLSCTX_INPROC_SERVER | windows.CLSCTX_INPROC_HANDLER |
-	windows.CLSCTX_LOCAL_SERVER | windows.CLSCTX_REMOTE_SERVER
-
-const (
-	hrSFALSE          = 0x00000001
-	hrRPCEChangedMode = 0x80010106
-)
-
-type hresult uint32
-
-func (h hresult) failed() bool { return int32(h) < 0 }
-func (h hresult) String() string {
-	return fmt.Sprintf("HRESULT 0x%08x", uint32(h))
-}
-
-var errAdapterNotFound = errors.New("adapter not present in network connections enumeration")
-
-// Vtable layouts. Slot order must match the declaration order in netlistmgr.h.
-// All NLM interfaces here derive from IDispatch, which derives from IUnknown.
-
-type iUnknownVtbl struct {
-	QueryInterface uintptr
-	AddRef         uintptr
-	Release        uintptr
-}
-
-type iDispatchVtbl struct {
-	iUnknownVtbl
-	GetTypeInfoCount uintptr
-	GetTypeInfo      uintptr
-	GetIDsOfNames    uintptr
-	Invoke           uintptr
-}
-
-type iNetworkListManagerVtbl struct {
-	iDispatchVtbl
-	GetNetworks           uintptr
-	GetNetwork            uintptr
-	GetNetworkConnections uintptr
-	GetNetworkConnection  uintptr
-	IsConnectedToInternet uintptr
-	IsConnected           uintptr
-	GetConnectivity       uintptr
-}
-
-type iNetworkListManager struct{ Vtbl *iNetworkListManagerVtbl }
-
-func (n *iNetworkListManager) Release() {
-	syscall.SyscallN(n.Vtbl.Release, uintptr(unsafe.Pointer(n)))
-}
-
-func (n *iNetworkListManager) GetNetworkConnections() (*iEnumNetworkConnections, error) {
-	var enum *iEnumNetworkConnections
-	r1, _, _ := syscall.SyscallN(n.Vtbl.GetNetworkConnections,
-		uintptr(unsafe.Pointer(n)), uintptr(unsafe.Pointer(&enum)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return nil, fmt.Errorf("INetworkListManager.GetNetworkConnections: %s", hr)
-	}
-	return enum, nil
-}
-
-type iEnumNetworkConnectionsVtbl struct {
-	iDispatchVtbl
-	NewEnum uintptr
-	Next    uintptr
-	Skip    uintptr
-	Reset   uintptr
-	Clone   uintptr
-}
-
-type iEnumNetworkConnections struct{ Vtbl *iEnumNetworkConnectionsVtbl }
-
-func (e *iEnumNetworkConnections) Release() {
-	syscall.SyscallN(e.Vtbl.Release, uintptr(unsafe.Pointer(e)))
-}
-
-// Next returns the next connection, or (nil, nil) at the end of the enumeration.
-func (e *iEnumNetworkConnections) Next() (*iNetworkConnection, error) {
-	var conn *iNetworkConnection
-	var fetched uint32
-	r1, _, _ := syscall.SyscallN(e.Vtbl.Next,
-		uintptr(unsafe.Pointer(e)), 1,
-		uintptr(unsafe.Pointer(&conn)), uintptr(unsafe.Pointer(&fetched)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return nil, fmt.Errorf("IEnumNetworkConnections.Next: %s", hr)
-	}
-	if fetched == 0 {
-		return nil, nil
-	}
-	return conn, nil
-}
-
-type iNetworkConnectionVtbl struct {
-	iDispatchVtbl
-	GetNetwork            uintptr
-	IsConnectedToInternet uintptr
-	IsConnected           uintptr
-	GetConnectivity       uintptr
-	GetConnectionId       uintptr
-	GetAdapterId          uintptr
-	GetDomainType         uintptr
-}
-
-type iNetworkConnection struct{ Vtbl *iNetworkConnectionVtbl }
-
-func (c *iNetworkConnection) Release() {
-	syscall.SyscallN(c.Vtbl.Release, uintptr(unsafe.Pointer(c)))
-}
-
-func (c *iNetworkConnection) GetAdapterId() (windows.GUID, error) {
-	var g windows.GUID
-	r1, _, _ := syscall.SyscallN(c.Vtbl.GetAdapterId,
-		uintptr(unsafe.Pointer(c)), uintptr(unsafe.Pointer(&g)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return windows.GUID{}, fmt.Errorf("INetworkConnection.GetAdapterId: %s", hr)
-	}
-	return g, nil
-}
-
-func (c *iNetworkConnection) GetNetwork() (*iNetwork, error) {
-	var net *iNetwork
-	r1, _, _ := syscall.SyscallN(c.Vtbl.GetNetwork,
-		uintptr(unsafe.Pointer(c)), uintptr(unsafe.Pointer(&net)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return nil, fmt.Errorf("INetworkConnection.GetNetwork: %s", hr)
-	}
-	return net, nil
-}
-
-type iNetworkVtbl struct {
-	iDispatchVtbl
-	GetName                    uintptr
-	SetName                    uintptr
-	GetDescription             uintptr
-	SetDescription             uintptr
-	GetNetworkId               uintptr
-	GetDomainType              uintptr
-	GetNetworkConnections      uintptr
-	GetTimeCreatedAndConnected uintptr
-	IsConnectedToInternet      uintptr
-	IsConnected                uintptr
-	GetConnectivity            uintptr
-	GetCategory                uintptr
-	SetCategory                uintptr
-}
-
-type iNetwork struct{ Vtbl *iNetworkVtbl }
-
-func (n *iNetwork) Release() {
-	syscall.SyscallN(n.Vtbl.Release, uintptr(unsafe.Pointer(n)))
-}
-
-func (n *iNetwork) GetCategory() (networkCategory, error) {
-	var c networkCategory
-	r1, _, _ := syscall.SyscallN(n.Vtbl.GetCategory,
-		uintptr(unsafe.Pointer(n)), uintptr(unsafe.Pointer(&c)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return 0, fmt.Errorf("INetwork.GetCategory: %s", hr)
-	}
-	return c, nil
-}
-
-func (n *iNetwork) SetCategory(c networkCategory) error {
-	r1, _, _ := syscall.SyscallN(n.Vtbl.SetCategory,
-		uintptr(unsafe.Pointer(n)), uintptr(int32(c)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return fmt.Errorf("INetwork.SetCategory: %s", hr)
-	}
-	return nil
-}
-
-// coInit initializes COM for the current OS thread. The returned function must
-// be deferred to balance a successful init. RPC_E_CHANGED_MODE means COM is
-// already initialized in a different mode on this thread, which is still fine
-// for our calls but we must not Uninitialize in that case.
-func coInit() (func(), error) {
-	err := windows.CoInitializeEx(0, windows.COINIT_MULTITHREADED)
-	if err == nil {
-		return windows.CoUninitialize, nil
-	}
-	if e, ok := err.(syscall.Errno); ok {
-		switch uint32(e) {
-		case hrSFALSE:
-			return windows.CoUninitialize, nil
-		case hrRPCEChangedMode:
-			return func() {}, nil
-		}
-	}
-	return nil, fmt.Errorf("CoInitializeEx: %w", err)
-}
-
-func createNetworkListManager() (*iNetworkListManager, error) {
-	var nlm *iNetworkListManager
-	r1, _, _ := procCoCreateInstance.Call(
-		uintptr(unsafe.Pointer(&clsidNetworkListManager)),
-		0,
-		uintptr(clsCtxAll),
-		uintptr(unsafe.Pointer(&iidINetworkListManager)),
-		uintptr(unsafe.Pointer(&nlm)),
-	)
-	if hr := hresult(r1); hr.failed() {
-		return nil, fmt.Errorf("CoCreateInstance(NetworkListManager): %s", hr)
-	}
-	return nlm, nil
-}
-
-// setNetworkCategory locates the network connection bound to adapterGUID and
-// sets the category of its parent network. Returns errAdapterNotFound if the
-// adapter is not yet visible in the NLM enumeration.
-func setNetworkCategory(adapterGUID windows.GUID, cat networkCategory) error {
-	deinit, err := coInit()
-	if err != nil {
-		return err
-	}
-	defer deinit()
-
-	nlm, err := createNetworkListManager()
-	if err != nil {
-		return err
-	}
-	defer nlm.Release()
-
-	enum, err := nlm.GetNetworkConnections()
-	if err != nil {
-		return err
-	}
-	defer enum.Release()
-
-	for {
-		conn, err := enum.Next()
-		if err != nil {
-			return err
-		}
-		if conn == nil {
-			return errAdapterNotFound
-		}
-
-		guid, err := conn.GetAdapterId()
-		if err != nil || guid != adapterGUID {
-			conn.Release()
-			continue
-		}
-
-		net, err := conn.GetNetwork()
-		conn.Release()
-		if err != nil {
-			return err
-		}
-		err = net.SetCategory(cat)
-		net.Release()
-		return err
-	}
-}
-
-// applyNetworkCategory polls until the wintun adapter shows up in the NLM
-// enumeration, then sets the category. Intended to run in its own goroutine.
-func applyNetworkCategory(l *slog.Logger, adapterGUID windows.GUID, cat networkCategory) {
-	// COM Init/Uninit must be paired on the same OS thread.
-	runtime.LockOSThread()
-	defer runtime.UnlockOSThread()
-
-	const (
-		attempts = 30
-		interval = 500 * time.Millisecond
-	)
-	for i := 0; i < attempts; i++ {
-		err := setNetworkCategory(adapterGUID, cat)
-		if err == nil {
-			l.Info("Set Windows network category", "category", cat.String())
-			return
-		}
-		if !errors.Is(err, errAdapterNotFound) {
-			l.Warn("Failed to set Windows network category", "error", err, "category", cat.String())
-			return
-		}
-		time.Sleep(interval)
-	}
-	l.Warn("Gave up waiting for adapter to appear in NLM enumeration; network category not set",
-		"category", cat.String(),
-		"waited", time.Duration(attempts)*interval,
-	)
-}

overlay/network_category_windows_test.go

@@ -1,109 +0,0 @@
-//go:build !e2e_testing
-// +build !e2e_testing
-
-package overlay
-
-import (
-	"testing"
-)
-
-func Test_parseNetworkCategory(t *testing.T) {
-	cases := []struct {
-		in        string
-		wantCat   networkCategory
-		wantApply bool
-		wantErr   bool
-	}{
-		{"", 0, false, false},
-		{"unset", 0, false, false},
-		{"  UNSET  ", 0, false, false},
-		{"private", networkCategoryPrivate, true, false},
-		{"Private", networkCategoryPrivate, true, false},
-		{"  PRIVATE  ", networkCategoryPrivate, true, false},
-		{"public", networkCategoryPublic, true, false},
-		{"PUBLIC", networkCategoryPublic, true, false},
-		{"domain", networkCategoryDomainAuthenticated, true, false},
-		{"DomainAuthenticated", networkCategoryDomainAuthenticated, true, false},
-		{"garbage", 0, false, true},
-		{"privates", 0, false, true},
-	}
-	for _, tc := range cases {
-		cat, apply, err := parseNetworkCategory(tc.in)
-		if (err != nil) != tc.wantErr {
-			t.Errorf("parseNetworkCategory(%q) err=%v, wantErr=%v", tc.in, err, tc.wantErr)
-			continue
-		}
-		if cat != tc.wantCat || apply != tc.wantApply {
-			t.Errorf("parseNetworkCategory(%q) = (%v, %v), want (%v, %v)", tc.in, cat, apply, tc.wantCat, tc.wantApply)
-		}
-	}
-}
-
-// Test_NLM_round_trip exercises every COM call path used by setNetworkCategory
-// without mutating the host's network state. It validates the CLSID/IID
-// constants and every vtable index by enumerating connections, fetching the
-// adapter id and parent network, reading the current category, and writing it
-// back unchanged.
-//
-// Requires Windows but does not require admin or the wintun driver. Skips if
-// no network connections are available (unlikely outside of an isolated
-// container).
-func Test_NLM_round_trip(t *testing.T) {
-	deinit, err := coInit()
-	if err != nil {
-		t.Fatalf("coInit: %v", err)
-	}
-	defer deinit()
-
-	nlm, err := createNetworkListManager()
-	if err != nil {
-		t.Fatalf("createNetworkListManager: %v", err)
-	}
-	defer nlm.Release()
-
-	enum, err := nlm.GetNetworkConnections()
-	if err != nil {
-		t.Fatalf("GetNetworkConnections: %v", err)
-	}
-	defer enum.Release()
-
-	saw := 0
-	for {
-		conn, err := enum.Next()
-		if err != nil {
-			t.Fatalf("EnumNetworkConnections.Next: %v", err)
-		}
-		if conn == nil {
-			break
-		}
-		saw++
-
-		if _, err := conn.GetAdapterId(); err != nil {
-			conn.Release()
-			t.Fatalf("INetworkConnection.GetAdapterId: %v", err)
-		}
-
-		net, err := conn.GetNetwork()
-		conn.Release()
-		if err != nil {
-			t.Fatalf("INetworkConnection.GetNetwork: %v", err)
-		}
-
-		cat, err := net.GetCategory()
-		if err != nil {
-			net.Release()
-			t.Fatalf("INetwork.GetCategory: %v", err)
-		}
-		// Set to the current value so the host's NLM state is unchanged but
-		// SetCategory's vtable slot is still validated end-to-end.
-		if err := net.SetCategory(cat); err != nil {
-			net.Release()
-			t.Fatalf("INetwork.SetCategory(%v): %v", cat, err)
-		}
-		net.Release()
-	}
-
-	if saw == 0 {
-		t.Skip("no NLM network connections available; skipping round-trip")
-	}
-}

overlay/overlaytest/noop.go

@@ -4,9 +4,9 @@ package overlaytest
 
 import (
 	"errors"
+	"io"
 	"net/netip"
 
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 )
 
@@ -31,8 +31,8 @@ func (NoopTun) Name() string {
 	return "noop"
 }
 
-func (NoopTun) Read() ([]tio.Packet, error) {
-	return nil, nil
+func (NoopTun) Read([]byte) (int, error) {
+	return 0, nil
 }
 
 func (NoopTun) Write([]byte) (int, error) {
@@ -43,14 +43,12 @@ func (NoopTun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (NoopTun) NewMultiQueueReader() error {
-	return errors.New("unsupported")
-}
-
-func (NoopTun) Readers() []tio.Queue {
-	return []tio.Queue{NoopTun{}}
+func (NoopTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, errors.New("unsupported")
 }
 
 func (NoopTun) Close() error {
 	return nil
 }
+
+func (NoopTun) TunPrefixLen() int { return 0 }

overlay/tio/queueset_gso_linux.go

@@ -1,79 +0,0 @@
-package tio
-
-import (
-	"encoding/binary"
-	"errors"
-	"fmt"
-
-	"golang.org/x/sys/unix"
-)
-
-type offloadQueueSet struct {
-	pq []*Offload
-	// pqi is exactly the same as pq, but stored as the interface type
-	pqi        []Queue
-	shutdownFd int
-	// usoEnabled is true when newTun successfully negotiated TUN_F_USO4|6
-	// with the kernel. Queues created by Add inherit this and surface it
-	// via Offload.USOSupported so coalescers can gate USO emission.
-	usoEnabled bool
-}
-
-// NewOffloadQueueSet creates a QueueSet that uses virtio_net_hdr to do
-// TSO segmentation in userspace. usoEnabled tells downstream queues whether
-// the kernel agreed to deliver/accept GSO_UDP_L4 superpackets — coalescers
-// should fall back to per-packet writes when this is false.
-func NewOffloadQueueSet(usoEnabled bool) (QueueSet, error) {
-	shutdownFd, err := unix.Eventfd(0, unix.EFD_NONBLOCK|unix.EFD_CLOEXEC)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create eventfd: %w", err)
-	}
-
-	out := &offloadQueueSet{
-		pq:         []*Offload{},
-		pqi:        []Queue{},
-		shutdownFd: shutdownFd,
-		usoEnabled: usoEnabled,
-	}
-
-	return out, nil
-}
-
-func (c *offloadQueueSet) Queues() []Queue {
-	return c.pqi
-}
-
-func (c *offloadQueueSet) Add(fd int) error {
-	x, err := newOffload(fd, c.shutdownFd, c.usoEnabled)
-	if err != nil {
-		return err
-	}
-	c.pq = append(c.pq, x)
-	c.pqi = append(c.pqi, x)
-
-	return nil
-}
-
-func (c *offloadQueueSet) wakeForShutdown() error {
-	var buf [8]byte
-	binary.NativeEndian.PutUint64(buf[:], 1)
-	_, err := unix.Write(c.shutdownFd, buf[:])
-	return err
-}
-
-func (c *offloadQueueSet) Close() error {
-	errs := []error{}
-
-	// Signal all readers blocked in poll to wake up and exit
-	if err := c.wakeForShutdown(); err != nil {
-		errs = append(errs, err)
-	}
-
-	for _, x := range c.pq {
-		if err := x.Close(); err != nil {
-			errs = append(errs, err)
-		}
-	}
-
-	return errors.Join(errs...)
-}

overlay/tio/queueset_poll_linux.go

@@ -1,69 +0,0 @@
-package tio
-
-import (
-	"encoding/binary"
-	"errors"
-	"fmt"
-
-	"golang.org/x/sys/unix"
-)
-
-type pollQueueSet struct {
-	pq []*Poll
-	// pqi is exactly the same as pq, but stored as the interface type
-	pqi        []Queue
-	shutdownFd int
-}
-
-func NewPollQueueSet() (QueueSet, error) {
-	shutdownFd, err := unix.Eventfd(0, unix.EFD_NONBLOCK|unix.EFD_CLOEXEC)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create eventfd: %w", err)
-	}
-
-	out := &pollQueueSet{
-		pq:         []*Poll{},
-		pqi:        []Queue{},
-		shutdownFd: shutdownFd,
-	}
-
-	return out, nil
-}
-
-func (c *pollQueueSet) Queues() []Queue {
-	return c.pqi
-}
-
-func (c *pollQueueSet) Add(fd int) error {
-	x, err := newPoll(fd, c.shutdownFd)
-	if err != nil {
-		return err
-	}
-	c.pq = append(c.pq, x)
-	c.pqi = append(c.pqi, x)
-
-	return nil
-}
-
-func (c *pollQueueSet) wakeForShutdown() error {
-	var buf [8]byte
-	binary.NativeEndian.PutUint64(buf[:], 1)
-	_, err := unix.Write(int(c.shutdownFd), buf[:])
-	return err
-}
-
-func (c *pollQueueSet) Close() error {
-	errs := []error{}
-
-	if err := c.wakeForShutdown(); err != nil {
-		errs = append(errs, err)
-	}
-
-	for _, x := range c.pq {
-		if err := x.Close(); err != nil {
-			errs = append(errs, err)
-		}
-	}
-
-	return errors.Join(errs...)
-}

overlay/tio/segment_bench_test.go

@@ -1,65 +0,0 @@
-//go:build linux && !android && !e2e_testing
-
-package tio
-
-import "testing"
-
-// fakeBatch stands in for batch.TxBatcher inside the bench — same shape
-// of pointer-capturing closure that sendInsideMessage builds.
-type fakeBatch struct{ buf [65536]byte }
-
-func (b *fakeBatch) Reserve(sz int) []byte { return b.buf[:sz] }
-func (b *fakeBatch) Commit([]byte)         {}
-
-type fakeHostInfo struct {
-	remoteIndexId uint32
-	counter       uint64
-}
-type fakeIface struct {
-	rebindCount uint8
-	hi          *fakeHostInfo
-}
-
-// BenchmarkSegmentSuperpacketAllocsTSO measures allocation per
-// SegmentSuperpacket call when a closure captures pointer-bearing
-// receivers — the realistic shape of sendInsideMessage's closure.
-func BenchmarkSegmentSuperpacketAllocsTSO(b *testing.B) {
-	const mss = 1400
-	const numSeg = 32
-	pkt := buildTSOv6(mss*numSeg, mss)
-	gso := GSOInfo{
-		Size:      mss,
-		HdrLen:    60, // 40 (IPv6) + 20 (TCP)
-		CsumStart: 40,
-		Proto:     GSOProtoTCP,
-	}
-	p := Packet{Bytes: pkt, GSO: gso}
-
-	hi := &fakeHostInfo{remoteIndexId: 0xdeadbeef}
-	f := &fakeIface{rebindCount: 7, hi: hi}
-	fb := &fakeBatch{}
-
-	// SegmentSuperpacket consumes pkt destructively; refresh from a master
-	// copy each iter (matches the production pattern where every TUN read
-	// hands the segmenter a fresh kernel-supplied buffer).
-	master := append([]byte(nil), pkt...)
-	work := make([]byte, len(pkt))
-	p.Bytes = work
-
-	b.ReportAllocs()
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		copy(work, master)
-		err := SegmentSuperpacket(p, func(seg []byte) error {
-			out := fb.Reserve(16 + len(seg) + 16)
-			out[0] = byte(f.rebindCount)
-			out[1] = byte(hi.counter)
-			hi.counter++
-			fb.Commit(out)
-			return nil
-		})
-		if err != nil {
-			b.Fatalf("SegmentSuperpacket: %v", err)
-		}
-	}
-}

overlay/tio/segment_other.go

@@ -1,22 +0,0 @@
-//go:build !linux || android || e2e_testing
-
-package tio
-
-import "fmt"
-
-func protoFromGSOType(_ uint8) (GSOProto, error) {
-	return 0, fmt.Errorf("GSO unsupported")
-}
-
-// SegmentSuperpacket invokes fn once per segment of pkt. On non-Linux
-// builds (and Android/e2e_testing) this package does not provide a Queue
-// implementation, so any caller that does construct a Packet here can only
-// be operating on non-superpacket bytes and the stub forwards them
-// directly. A non-zero GSO field is a programming error from the caller
-// and returns an explicit error rather than silently misbehaving.
-func SegmentSuperpacket(pkt Packet, fn func(seg []byte) error) error {
-	if pkt.GSO.IsSuperpacket() {
-		return fmt.Errorf("tio: GSO superpacket on platform without segmentation support")
-	}
-	return fn(pkt.Bytes)
-}

overlay/tio/tio.go

@@ -1,170 +0,0 @@
-package tio
-
-import (
-	"io"
-)
-
-// QueueSet holds one or many Queue objects and helps close them in an orderly way.
-type QueueSet interface {
-	io.Closer
-	Queues() []Queue
-
-	// Add takes a tun fd, adds it to the set, and prepares it for use as a Queue.
-	Add(fd int) error
-}
-
-// Capabilities advertises which kernel offload features a Queue
-// successfully negotiated. Callers consult this to decide which coalescers
-// to wire onto the write path — a Queue without TSO can't usefully accept a
-// TCPCoalescer, and a Queue without USO can't accept a UDPCoalescer.
-type Capabilities struct {
-	// TSO means the FD was opened with IFF_VNET_HDR and the kernel agreed
-	// to TUN_F_TSO4|TSO6 — i.e. WriteGSO with GSOProtoTCP is safe.
-	TSO bool
-	// USO means the kernel additionally agreed to TUN_F_USO4|USO6, so
-	// WriteGSO with GSOProtoUDP is safe. Linux ≥ 6.2.
-	USO bool
-}
-
-// Queue is a readable/writable Poll queue. One Queue is driven by a single
-// read goroutine plus a single writer (see Write below).
-type Queue interface {
-	io.Closer
-
-	// Read returns one or more packets. The returned Packet.Bytes slices
-	// are borrowed from the Queue's internal buffer and are only valid
-	// until the next Read or Close on this Queue - callers must encrypt
-	// or copy each slice before the next call. A Packet may carry a
-	// GSO/USO superpacket (see GSOInfo); when GSO.IsSuperpacket() is
-	// true the caller must segment Bytes before treating it as a single
-	// IP datagram. Not safe for concurrent Reads.
-	Read() ([]Packet, error)
-
-	// Write emits a single packet on the plaintext (outside→inside)
-	// delivery path. Not safe for concurrent Writes.
-	Write(p []byte) (int, error)
-}
-
-// Packet is the unit Queue.Read returns. Bytes points into the queue's
-// internal buffer and is only valid until the next Read or Close on the
-// queue that produced it. GSO is the zero value for an already-segmented
-// IP datagram; when non-zero it describes a kernel-supplied TSO/USO
-// superpacket the caller must segment before consuming.
-type Packet struct {
-	Bytes []byte
-	GSO   GSOInfo
-}
-
-// GSOInfo describes a kernel-supplied superpacket sitting in Packet.Bytes.
-// The zero value means "not a superpacket" — Bytes is one regular IP
-// datagram and no segmentation is required.
-type GSOInfo struct {
-	// Size is the GSO segment size: max payload bytes per segment
-	// (== TCP MSS for TSO, == UDP payload chunk for USO). Zero means
-	// not a superpacket.
-	Size uint16
-	// HdrLen is the total L3+L4 header length within Bytes (already
-	// corrected via correctHdrLen, so safe to slice on).
-	HdrLen uint16
-	// CsumStart is the L4 header offset inside Bytes (== L3 header
-	// length).
-	CsumStart uint16
-	// Proto picks the L4 protocol (TCP or UDP) so the segmenter knows
-	// which checksum/header layout to apply.
-	Proto GSOProto
-}
-
-// IsSuperpacket reports whether g describes a multi-segment GSO/USO
-// superpacket that needs segmentation before its bytes can be encrypted
-// and sent on the wire.
-func (g GSOInfo) IsSuperpacket() bool { return g.Size > 0 }
-
-// Clone returns a Packet whose Bytes is a freshly allocated copy of p.Bytes,
-// safe to retain past the next Read or Close on the originating Queue.
-// GSO metadata is copied verbatim. Use this only when a caller genuinely
-// needs to outlive the borrowed-slice contract — the hot path reads should
-// continue to consume the borrow synchronously to avoid the allocation.
-func (p Packet) Clone() Packet {
-	if p.Bytes == nil {
-		return p
-	}
-	cp := make([]byte, len(p.Bytes))
-	copy(cp, p.Bytes)
-	return Packet{Bytes: cp, GSO: p.GSO}
-}
-
-// CapsProvider is an optional interface implemented by Queues that
-// successfully negotiated kernel offload features at open time. Callers
-// pick a write-path coalescer based on the result. Queues that don't
-// implement it are treated as having no offload capability — callers must
-// fall back to plain per-packet writes.
-type CapsProvider interface {
-	Capabilities() Capabilities
-}
-
-// QueueCapabilities returns q's negotiated offload capabilities, or the
-// zero value when q does not advertise any.
-func QueueCapabilities(q Queue) Capabilities {
-	if cp, ok := q.(CapsProvider); ok {
-		return cp.Capabilities()
-	}
-	return Capabilities{}
-}
-
-// GSOProto selects the L4 protocol for a GSO superpacket. Determines which
-// VIRTIO_NET_HDR_GSO_* type the writer stamps and which checksum offset
-// inside the transport header virtio NEEDS_CSUM expects.
-type GSOProto uint8
-
-const (
-	GSOProtoTCP GSOProto = iota
-	GSOProtoUDP
-)
-
-// GSOWriter is implemented by Queues that can emit a TCP or UDP superpacket
-// assembled from a header prefix plus one or more borrowed payload
-// fragments, in a single vectored write (writev with a leading
-// virtio_net_hdr). This lets the coalescer avoid copying payload bytes
-// between the caller's decrypt buffer and the TUN. Backends without GSO
-// support do not implement this interface and coalescing is skipped.
-//
-// hdr contains the IPv4/IPv6 header prefix (mutable - callers will have
-// filled in total length and IP csum). transportHdr is the TCP or UDP
-// header (mutable - the L4 checksum field must hold the pseudo-header
-// partial, single-fold not inverted, per virtio NEEDS_CSUM semantics).
-// pays are non-overlapping payload fragments whose concatenation is the
-// full superpacket payload; they are read-only from the writer's
-// perspective and must remain valid until the call returns. Every segment
-// in pays except possibly the last is exactly the same size. proto picks
-// the L4 protocol so the writer knows which GSOType / CsumOffset to set.
-//
-// Callers should also consult CapsProvider (via SupportsGSO or
-// QueueCapabilities) for the per-protocol negotiated capability; an
-// implementation of GSOWriter is necessary but not sufficient since USO
-// may not have been negotiated even when TSO was.
-type GSOWriter interface {
-	WriteGSO(hdr []byte, transportHdr []byte, pays [][]byte, proto GSOProto) error
-}
-
-// SupportsGSO reports whether w implements GSOWriter and the underlying
-// queue advertises the negotiated capability for `want`. A writer that
-// implements GSOWriter but not CapsProvider is treated as permissive
-// (used by tests and fakes that don't negotiate).
-func SupportsGSO(w any, want GSOProto) (GSOWriter, bool) {
-	gw, ok := w.(GSOWriter)
-	if !ok {
-		return nil, false
-	}
-	cp, ok := w.(CapsProvider)
-	if !ok {
-		return gw, true
-	}
-	caps := cp.Capabilities()
-	switch want {
-	case GSOProtoTCP:
-		return gw, caps.TSO
-	case GSOProtoUDP:
-		return gw, caps.USO
-	}
-	return gw, false
-}

overlay/tio/tio_gso_linux.go

@@ -1,461 +0,0 @@
-package tio
-
-import (
-	"fmt"
-	"io"
-	"log/slog"
-	"os"
-	"sync"
-	"sync/atomic"
-	"syscall"
-	"unsafe"
-
-	"golang.org/x/sys/unix"
-
-	"github.com/slackhq/nebula/overlay/tio/virtio"
-)
-
-// tunRxBufSize is the per-Read worst-case footprint inside rxBuf: one
-// kernel-supplied packet body, which is at most ~64 KiB (tunReadBufSize).
-// Segmentation happens at encrypt time on a per-routine MTU-sized scratch
-// (see SegmentSuperpacket), so rxBuf only holds raw kernel-supplied bytes.
-// We round up to give comfortable margin for the drain headroom check
-// below.
-const tunRxBufSize = 64 * 1024
-
-// tunRxBufCap is the total size we allocate for the per-reader rx
-// buffer. With reads landing directly in rxBuf, each drain iteration
-// consumes up to tunRxBufSize of headroom for the kernel-supplied bytes.
-// Sized to two such iterations so the initial blocking read plus one
-// drain read both fit without partial-drop.
-const tunRxBufCap = tunRxBufSize * 2
-
-// tunDrainCap caps how many packets a single Read will accumulate via
-// the post-wake drain loop. Sized to soak up a burst of small ACKs while
-// bounding how much work a single caller holds before handing off.
-const tunDrainCap = 64
-
-// gsoMaxIovs caps the iovec budget WriteGSO assembles per call: 3 fixed
-// entries (virtio_net_hdr, IP hdr, transport hdr) plus up to gsoMaxIovs-3
-// payload fragments. Sized comfortably above the typical kernel GSO
-// segment cap (Linux UDP_GRO is 64) so realistic coalesced bursts never
-// touch the limit. iovecs are tiny (16 bytes), so the entire scratch is
-// 4 KiB — fine to keep resident on every queue. WriteGSO returns an error
-// rather than reallocating when a caller exceeds this budget.
-const gsoMaxIovs = 256
-
-// validVnetHdr is the 10-byte virtio_net_hdr we prepend to every non-GSO TUN
-// write. Only flag set is VIRTIO_NET_HDR_F_DATA_VALID, which marks the skb
-// CHECKSUM_UNNECESSARY so the receiving network stack skips L4 checksum
-// verification. All packets that reach the plain Write paths already carry
-// a valid L4 checksum (either supplied by a remote peer whose ciphertext we
-// AEAD-authenticated, produced by segmentTCPYield/segmentUDPYield during
-// superpacket segmentation, or built locally by CreateRejectPacket), so
-// trusting them is safe.
-var validVnetHdr = [virtio.Size]byte{unix.VIRTIO_NET_HDR_F_DATA_VALID}
-
-// Offload wraps a TUN file descriptor with poll-based reads. The FD provided will be changed to non-blocking.
-// A shared eventfd allows Close to wake all readers blocked in poll.
-type Offload struct {
-	fd         int
-	shutdownFd int
-	readPoll   [2]unix.PollFd
-	writePoll  [2]unix.PollFd
-	// writeLock serializes blockOnWrite's read+clear of writePoll[*].Revents.
-	// Any goroutine that calls Write may end up parked in poll(2); without
-	// the lock concurrent waiters could race the Revents reset and lose
-	// events.
-	writeLock sync.Mutex
-	closed    atomic.Bool
-	rxBuf     []byte   // backing store for kernel-handed packets read this drain
-	rxOff     int      // cursor into rxBuf for the current Read drain
-	pending   []Packet // packets returned from the most recent Read
-
-	// readVnetScratch holds the 10-byte virtio_net_hdr split off the front of
-	// every TUN read via readv(2). Decoupling the header from the packet body
-	// lets us read the body directly into rxBuf at the current rxOff with
-	// no userspace copy on the GSO_NONE fast path.
-	readVnetScratch [virtio.Size]byte
-	// readIovs is the readv(2) iovec scratch wired once at construction —
-	// iovec[0] points at readVnetScratch; iovec[1].Base/Len is updated per
-	// read to address the current rxBuf slot.
-	readIovs [2]unix.Iovec
-
-	// usoEnabled records whether the kernel agreed to TUN_F_USO* on this FD,
-	// so writers can decide whether emitting GSO_UDP_L4 superpackets is safe.
-	usoEnabled bool
-
-	// gsoHdrBuf is a per-queue 10-byte scratch for the virtio_net_hdr emitted
-	// by WriteGSO. Kept separate from the read-only package-level validVnetHdr
-	// so non-GSO Writes can ship that constant directly while WriteGSO
-	// rewrites this scratch on every call.
-	gsoHdrBuf [virtio.Size]byte
-	// gsoIovs is the writev iovec scratch for WriteGSO. Pre-sized to
-	// gsoMaxIovs at construction; never grown. WriteGSO returns an error
-	// (and drops the call) if a caller hands it more fragments than fit.
-	gsoIovs []unix.Iovec
-}
-
-func newOffload(fd int, shutdownFd int, usoEnabled bool) (*Offload, error) {
-	if err := unix.SetNonblock(fd, true); err != nil {
-		return nil, fmt.Errorf("failed to set tun fd non-blocking: %w", err)
-	}
-
-	out := &Offload{
-		fd:         fd,
-		shutdownFd: shutdownFd,
-		usoEnabled: usoEnabled,
-		closed:     atomic.Bool{},
-		readPoll: [2]unix.PollFd{
-			{Fd: int32(fd), Events: unix.POLLIN},
-			{Fd: int32(shutdownFd), Events: unix.POLLIN},
-		},
-		writePoll: [2]unix.PollFd{
-			{Fd: int32(fd), Events: unix.POLLOUT},
-			{Fd: int32(shutdownFd), Events: unix.POLLIN},
-		},
-		writeLock: sync.Mutex{},
-
-		rxBuf:   make([]byte, tunRxBufCap),
-		gsoIovs: make([]unix.Iovec, 2, gsoMaxIovs),
-	}
-
-	out.gsoIovs[0].Base = &out.gsoHdrBuf[0]
-	out.gsoIovs[0].SetLen(virtio.Size)
-
-	// readIovs[0] is wired once to the virtio_net_hdr scratch; per-read we
-	// only repoint readIovs[1] at the next rxBuf slot (see readPacket).
-	out.readIovs[0].Base = &out.readVnetScratch[0]
-	out.readIovs[0].SetLen(virtio.Size)
-
-	return out, nil
-}
-
-func (r *Offload) blockOnRead() error {
-	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
-	var err error
-	for {
-		_, err = unix.Poll(r.readPoll[:], -1)
-		if err != unix.EINTR {
-			break
-		}
-	}
-	//always reset these!
-	tunEvents := r.readPoll[0].Revents
-	shutdownEvents := r.readPoll[1].Revents
-	r.readPoll[0].Revents = 0
-	r.readPoll[1].Revents = 0
-	//do the err check before trusting the potentially bogus bits we just got
-	if err != nil {
-		return err
-	}
-	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
-		return os.ErrClosed
-	} else if tunEvents&problemFlags != 0 {
-		return os.ErrClosed
-	}
-	return nil
-}
-
-func (r *Offload) blockOnWrite() error {
-	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
-	var err error
-	for {
-		_, err = unix.Poll(r.writePoll[:], -1)
-		if err != unix.EINTR {
-			break
-		}
-	}
-	//always reset these!
-	r.writeLock.Lock()
-	tunEvents := r.writePoll[0].Revents
-	shutdownEvents := r.writePoll[1].Revents
-	r.writePoll[0].Revents = 0
-	r.writePoll[1].Revents = 0
-	r.writeLock.Unlock()
-	//do the err check before trusting the potentially bogus bits we just got
-	if err != nil {
-		return err
-	}
-	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
-		return os.ErrClosed
-	} else if tunEvents&problemFlags != 0 {
-		return os.ErrClosed
-	}
-	return nil
-}
-
-// readPacket issues a single readv(2) splitting the virtio_net_hdr off
-// into readVnetScratch and reading the packet body directly into rxBuf at
-// the current rxOff. Returns the body length (zero virtio header bytes,
-// just the IP packet/superpacket). block controls whether EAGAIN is
-// retried via poll: the initial read of a drain blocks; subsequent drain
-// reads do not.
-//
-// The body iovec capacity is always tunReadBufSize; callers (the Read
-// drain loop) gate entry on tunRxBufCap-rxOff >= tunRxBufSize, sized to
-// hold one worst-case kernel-supplied packet body. Without that gate the
-// body iovec could be smaller than the next inbound packet and the
-// kernel would truncate.
-func (r *Offload) readPacket(block bool) (int, error) {
-	for {
-		r.readIovs[1].Base = &r.rxBuf[r.rxOff]
-		r.readIovs[1].SetLen(tunReadBufSize)
-		n, _, errno := syscall.Syscall(unix.SYS_READV, uintptr(r.fd), uintptr(unsafe.Pointer(&r.readIovs[0])), uintptr(len(r.readIovs)))
-		if errno == 0 {
-			if int(n) < virtio.Size {
-				return 0, io.ErrShortWrite
-			}
-			return int(n) - virtio.Size, nil
-		}
-		if errno == unix.EAGAIN {
-			if !block {
-				return 0, errno
-			}
-			if err := r.blockOnRead(); err != nil {
-				return 0, err
-			}
-			continue
-		}
-		if errno == unix.EINTR {
-			continue
-		}
-		if errno == unix.EBADF {
-			return 0, os.ErrClosed
-		}
-		return 0, errno
-	}
-}
-
-// Read returns one or more packets from the tun. Each Packet either
-// carries a single ready-to-use IP datagram (GSO zero) or a TSO/USO
-// superpacket plus the GSOInfo a caller needs to segment it (see
-// SegmentSuperpacket). The first read blocks via poll; once the fd is
-// known readable we drain additional packets non-blocking until the
-// kernel queue is empty (EAGAIN), we've collected tunDrainCap packets,
-// or we're out of rxBuf headroom. This amortizes the poll wake over
-// bursts of small packets (e.g. TCP ACKs). Packet.Bytes slices point
-// into the Offload's internal buffer and are only valid until the next
-// Read or Close on this Queue.
-func (r *Offload) Read() ([]Packet, error) {
-	r.pending = r.pending[:0]
-	r.rxOff = 0
-
-	// Initial (blocking) read. Retry on decode errors so a single bad
-	// packet does not stall the reader.
-	for {
-		n, err := r.readPacket(true)
-		if err != nil {
-			return nil, err
-		}
-		if err := r.decodeRead(n); err != nil {
-			// Drop and read again — a bad packet should not kill the reader.
-			continue
-		}
-		break
-	}
-
-	// Drain: non-blocking reads until the kernel queue is empty, the drain
-	// cap is reached, or rxBuf no longer has room for another worst-case
-	// kernel-supplied packet (tunRxBufSize).
-	for len(r.pending) < tunDrainCap && tunRxBufCap-r.rxOff >= tunRxBufSize {
-		n, err := r.readPacket(false)
-		if err != nil {
-			// EAGAIN / EINTR / anything else: stop draining. We already
-			// have a valid batch from the first read.
-			break
-		}
-		if n <= 0 {
-			break
-		}
-		if err := r.decodeRead(n); err != nil {
-			// Drop this packet and stop the drain; we'd rather hand off
-			// what we have than keep spinning here.
-			break
-		}
-	}
-
-	return r.pending, nil
-}
-
-// decodeRead processes the packet sitting in rxBuf at rxOff (length
-// pktLen). The bytes stay in rxBuf — for GSO_NONE we slice them as a
-// regular IP datagram (running finishChecksum if NEEDS_CSUM is set);
-// for TSO/USO superpackets we attach the corrected GSO metadata so the
-// caller can segment lazily at encrypt time. rxOff advances past the
-// kernel-supplied body and nothing else, since segmentation no longer
-// writes back into rxBuf.
-func (r *Offload) decodeRead(pktLen int) error {
-	if pktLen <= 0 {
-		return fmt.Errorf("short tun read: %d", pktLen)
-	}
-	var hdr virtio.Hdr
-	hdr.Decode(r.readVnetScratch[:])
-
-	body := r.rxBuf[r.rxOff : r.rxOff+pktLen]
-
-	if hdr.GSOType == unix.VIRTIO_NET_HDR_GSO_NONE {
-		if hdr.Flags&unix.VIRTIO_NET_HDR_F_NEEDS_CSUM != 0 {
-			if err := virtio.FinishChecksum(body, hdr); err != nil {
-				return err
-			}
-		}
-		r.pending = append(r.pending, Packet{Bytes: body})
-		r.rxOff += pktLen
-		return nil
-	}
-
-	// GSO superpacket: validate, fix the kernel-supplied HdrLen on the
-	// FORWARD path (CorrectHdrLen), pick the L4 protocol, and attach
-	// the metadata. The bytes stay in rxBuf untouched, segmentation
-	// happens in SegmentSuperpacket at encrypt time.
-	if err := virtio.CheckValid(body, hdr); err != nil {
-		return err
-	}
-	if err := virtio.CorrectHdrLen(body, &hdr); err != nil {
-		return err
-	}
-	proto, err := protoFromGSOType(hdr.GSOType)
-	if err != nil {
-		return err
-	}
-	r.pending = append(r.pending, Packet{
-		Bytes: body,
-		GSO: GSOInfo{
-			Size:      hdr.GSOSize,
-			HdrLen:    hdr.HdrLen,
-			CsumStart: hdr.CsumStart,
-			Proto:     proto,
-		},
-	})
-	r.rxOff += pktLen
-	return nil
-}
-
-func (r *Offload) Write(buf []byte) (int, error) {
-	iovs := [2]unix.Iovec{
-		{Base: &validVnetHdr[0]},
-		{Base: &buf[0]},
-	}
-	iovs[0].SetLen(virtio.Size)
-	iovs[1].SetLen(len(buf))
-	return r.writeWithScratch(buf, &iovs)
-}
-
-func (r *Offload) writeWithScratch(buf []byte, iovs *[2]unix.Iovec) (int, error) {
-	if len(buf) == 0 {
-		return 0, nil
-	}
-	iovs[1].Base = &buf[0]
-	iovs[1].SetLen(len(buf))
-	return r.rawWrite(unsafe.Slice(&iovs[0], len(iovs)))
-}
-
-func (r *Offload) rawWrite(iovs []unix.Iovec) (int, error) {
-	for {
-		n, _, errno := syscall.Syscall(unix.SYS_WRITEV, uintptr(r.fd), uintptr(unsafe.Pointer(&iovs[0])), uintptr(len(iovs)))
-		if errno == 0 {
-			if int(n) < virtio.Size {
-				return 0, io.ErrShortWrite
-			}
-			return int(n) - virtio.Size, nil
-		}
-		if errno == unix.EAGAIN {
-			if err := r.blockOnWrite(); err != nil {
-				return 0, err
-			}
-			continue
-		}
-		if errno == unix.EINTR {
-			continue
-		}
-		if errno == unix.EBADF {
-			return 0, os.ErrClosed
-		}
-		return 0, errno
-	}
-}
-
-// Capabilities reports the offload features negotiated for this Queue. TSO
-// is always true for Offload (we only construct it on IFF_VNET_HDR FDs);
-// USO is true only when the kernel agreed to TUN_F_USO4|6 at open time
-// (Linux ≥ 6.2).
-func (r *Offload) Capabilities() Capabilities {
-	return Capabilities{TSO: true, USO: r.usoEnabled}
-}
-
-func (r *Offload) WriteGSO(hdr []byte, transportHdr []byte, pays [][]byte, proto GSOProto) error {
-	if len(hdr) == 0 || len(pays) == 0 || len(transportHdr) == 0 {
-		return nil
-	}
-	// L4 checksum offset inside transportHdr: TCP=16 (the `check` field after
-	// seq/ack/dataoff/flags/window), UDP=6 (after sport/dport/length).
-	var csumOff uint16
-	switch proto {
-	case GSOProtoUDP:
-		csumOff = 6
-	default:
-		csumOff = 16
-	}
-	vhdr := virtio.Hdr{
-		Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-		HdrLen:     uint16(len(hdr) + len(transportHdr)),
-		GSOSize:    uint16(len(pays[0])),
-		CsumStart:  uint16(len(hdr)),
-		CsumOffset: csumOff,
-	}
-	if len(pays) > 1 {
-		ipVer := hdr[0] >> 4
-		switch {
-		case proto == GSOProtoUDP && (ipVer == 4 || ipVer == 6):
-			vhdr.GSOType = unix.VIRTIO_NET_HDR_GSO_UDP_L4
-		case ipVer == 6:
-			vhdr.GSOType = unix.VIRTIO_NET_HDR_GSO_TCPV6
-		case ipVer == 4:
-			vhdr.GSOType = unix.VIRTIO_NET_HDR_GSO_TCPV4
-		default:
-			vhdr.GSOType = unix.VIRTIO_NET_HDR_GSO_NONE
-			vhdr.GSOSize = 0
-		}
-	} else {
-		vhdr.GSOType = unix.VIRTIO_NET_HDR_GSO_NONE
-		vhdr.GSOSize = 0
-	}
-	vhdr.Encode(r.gsoHdrBuf[:])
-
-	// Build the iovec array: [virtio_hdr, hdr, transportHdr, pays...]. r.gsoIovs[0] is
-	// wired to gsoHdrBuf at construction and never changes.
-	need := 3 + len(pays)
-	if need > cap(r.gsoIovs) {
-		slog.Default().Warn("tio: WriteGSO iovec budget exceeded; dropping superpacket",
-			"need", need, "cap", cap(r.gsoIovs), "segments", len(pays))
-		return fmt.Errorf("tio: WriteGSO needs %d iovecs but cap is %d", need, cap(r.gsoIovs))
-	}
-	r.gsoIovs = r.gsoIovs[:need]
-	r.gsoIovs[1].Base = &hdr[0]
-	r.gsoIovs[1].SetLen(len(hdr))
-	r.gsoIovs[2].Base = &transportHdr[0]
-	r.gsoIovs[2].SetLen(len(transportHdr))
-	for i, p := range pays {
-		r.gsoIovs[3+i].Base = &p[0]
-		r.gsoIovs[3+i].SetLen(len(p))
-	}
-
-	_, err := r.rawWrite(r.gsoIovs)
-	return err
-}
-
-func (r *Offload) Close() error {
-	if r.closed.Swap(true) {
-		return nil
-	}
-
-	//shutdownFd is owned by the container, so we should not close it
-	var err error
-	if r.fd >= 0 {
-		err = unix.Close(r.fd)
-		r.fd = -1
-	}
-
-	return err
-}

overlay/tio/tio_poll_linux.go

@@ -1,164 +0,0 @@
-package tio
-
-import (
-	"fmt"
-	"os"
-	"sync/atomic"
-
-	"golang.org/x/sys/unix"
-)
-
-// Maximum size we accept for a single read from a TUN with IFF_VNET_HDR. A
-// TSO superpacket can be up to 64KiB of payload plus a single L2/L3/L4 header
-// prefix plus the virtio header.
-const tunReadBufSize = 65535
-
-type Poll struct {
-	fd int
-
-	readPoll  [2]unix.PollFd
-	writePoll [2]unix.PollFd
-	closed    atomic.Bool
-
-	readBuf  []byte
-	batchRet [1]Packet
-}
-
-func newPoll(fd int, shutdownFd int) (*Poll, error) {
-	if err := unix.SetNonblock(fd, true); err != nil {
-		_ = unix.Close(fd)
-		return nil, fmt.Errorf("failed to set Poll device as nonblocking: %w", err)
-	}
-
-	out := &Poll{
-		fd:      fd,
-		readBuf: make([]byte, tunReadBufSize),
-		readPoll: [2]unix.PollFd{
-			{Fd: int32(fd), Events: unix.POLLIN},
-			{Fd: int32(shutdownFd), Events: unix.POLLIN},
-		},
-		writePoll: [2]unix.PollFd{
-			{Fd: int32(fd), Events: unix.POLLOUT},
-			{Fd: int32(shutdownFd), Events: unix.POLLIN},
-		},
-	}
-	return out, nil
-}
-
-// blockOnRead waits until the Poll fd is readable or shutdown has been signaled.
-// Returns os.ErrClosed if Close was called.
-func (t *Poll) blockOnRead() error {
-	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
-	var err error
-	for {
-		_, err = unix.Poll(t.readPoll[:], -1)
-		if err != unix.EINTR {
-			break
-		}
-	}
-	tunEvents := t.readPoll[0].Revents
-	shutdownEvents := t.readPoll[1].Revents
-	t.readPoll[0].Revents = 0
-	t.readPoll[1].Revents = 0
-	if err != nil {
-		return err
-	}
-	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
-		return os.ErrClosed
-	}
-	if tunEvents&problemFlags != 0 {
-		return os.ErrClosed
-	}
-	return nil
-}
-
-func (t *Poll) blockOnWrite() error {
-	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
-	var err error
-	for {
-		_, err = unix.Poll(t.writePoll[:], -1)
-		if err != unix.EINTR {
-			break
-		}
-	}
-	tunEvents := t.writePoll[0].Revents
-	shutdownEvents := t.writePoll[1].Revents
-	t.writePoll[0].Revents = 0
-	t.writePoll[1].Revents = 0
-	if err != nil {
-		return err
-	}
-	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
-		return os.ErrClosed
-	}
-	if tunEvents&problemFlags != 0 {
-		return os.ErrClosed
-	}
-	return nil
-}
-
-func (t *Poll) Read() ([]Packet, error) {
-	n, err := t.readOne(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
-}
-
-func (t *Poll) readOne(to []byte) (int, error) {
-	for {
-		n, errno := unix.Read(t.fd, to)
-		if errno == nil {
-			return n, nil
-		}
-		switch errno {
-		case unix.EAGAIN:
-			if err := t.blockOnRead(); err != nil {
-				return 0, err
-			}
-		case unix.EINTR:
-			// retry
-		case unix.EBADF:
-			return 0, os.ErrClosed
-		default:
-			return 0, errno
-		}
-	}
-}
-
-// Write is only valid for single threaded use
-func (t *Poll) Write(from []byte) (int, error) {
-	for {
-		n, errno := unix.Write(t.fd, from)
-		if errno == nil {
-			return n, nil
-		}
-		switch errno {
-		case unix.EAGAIN:
-			if err := t.blockOnWrite(); err != nil {
-				return 0, err
-			}
-		case unix.EINTR:
-			// retry
-		case unix.EBADF:
-			return 0, os.ErrClosed
-		default:
-			return 0, errno
-		}
-	}
-}
-
-func (t *Poll) Close() error {
-	if t.closed.Swap(true) {
-		return nil
-	}
-	//shutdownFd is owned by the container, so we should not close it
-	var err error
-	if t.fd >= 0 {
-		err = unix.Close(t.fd)
-		t.fd = -1
-	}
-
-	return err
-}

overlay/tio/tun_file_linux_test.go

@@ -1,82 +0,0 @@
-//go:build linux && !android && !e2e_testing
-// +build linux,!android,!e2e_testing
-
-package tio
-
-import (
-	"errors"
-	"os"
-	"sync"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/require"
-	"golang.org/x/sys/unix"
-)
-
-// newReadPipe returns a read fd. The matching write fd is registered for cleanup.
-// The caller takes ownership of the read fd (pass it into a QueueSet).
-func newReadPipe(t *testing.T) int {
-	t.Helper()
-	var fds [2]int
-	if err := unix.Pipe2(fds[:], unix.O_CLOEXEC); err != nil {
-		t.Fatalf("pipe2: %v", err)
-	}
-	t.Cleanup(func() { _ = unix.Close(fds[1]) })
-	return fds[0]
-}
-
-func TestPoll_WakeForShutdown_WakesFriends(t *testing.T) {
-	pipe1 := newReadPipe(t)
-	pipe2 := newReadPipe(t)
-	parent, err := NewPollQueueSet()
-	require.NoError(t, err)
-	require.NoError(t, parent.Add(pipe1))
-	require.NoError(t, parent.Add(pipe2))
-	t.Cleanup(func() {
-		_ = unix.Close(pipe1)
-		_ = unix.Close(pipe2)
-	})
-
-	readers := parent.Queues()
-	errs := make([]error, len(readers))
-	var wg sync.WaitGroup
-	for i, r := range readers {
-		wg.Add(1)
-		go func(i int, r Queue) {
-			defer wg.Done()
-			_, errs[i] = r.Read()
-		}(i, r)
-	}
-
-	time.Sleep(50 * time.Millisecond)
-
-	if err := parent.Close(); err != nil {
-		t.Fatalf("Close: %v", err)
-	}
-
-	done := make(chan struct{})
-	go func() { wg.Wait(); close(done) }()
-	select {
-	case <-done:
-	case <-time.After(2 * time.Second):
-		t.Fatal("readers did not wake")
-	}
-
-	for i, err := range errs {
-		if !errors.Is(err, os.ErrClosed) {
-			t.Errorf("reader %d: expected os.ErrClosed, got %v", i, err)
-		}
-	}
-}
-
-func TestPoll_Close_Idempotent(t *testing.T) {
-	tf, err := newPoll(newReadPipe(t), 1)
-	require.NoError(t, err)
-	if err := tf.Close(); err != nil {
-		t.Fatalf("first Close: %v", err)
-	}
-	if err := tf.Close(); err != nil {
-		t.Fatalf("second Close should be a no-op, got %v", err)
-	}
-}

overlay/tio/tun_linux_offload.go

@@ -1,51 +0,0 @@
-//go:build linux && !android && !e2e_testing
-// +build linux,!android,!e2e_testing
-
-package tio
-
-import (
-	"fmt"
-
-	"golang.org/x/sys/unix"
-
-	"github.com/slackhq/nebula/overlay/tio/virtio"
-)
-
-// protoFromGSOType maps a virtio_net_hdr GSOType to the GSOProto value the
-// segment-time helpers use. Returns an error for GSO_NONE or any unknown
-// value — the caller should only invoke this on a confirmed superpacket.
-func protoFromGSOType(t uint8) (GSOProto, error) {
-	switch t {
-	case unix.VIRTIO_NET_HDR_GSO_TCPV4, unix.VIRTIO_NET_HDR_GSO_TCPV6:
-		return GSOProtoTCP, nil
-	case unix.VIRTIO_NET_HDR_GSO_UDP_L4:
-		return GSOProtoUDP, nil
-	default:
-		return 0, fmt.Errorf("unsupported virtio gso type: %d", t)
-	}
-}
-
-// SegmentSuperpacket invokes fn once per segment of pkt. For non-GSO pkts
-// fn is called once with pkt.Bytes (no segmentation, no copy). For GSO/USO
-// superpackets fn is called once per segment with a slice of pkt.Bytes
-// holding that segment's plaintext (a freshly-patched L3+L4 header sliced
-// in front of the original payload chunk). The slide is destructive: pkt is
-// consumed by this call and its bytes are in an undefined state when
-// SegmentSuperpacket returns. Callers must not retain pkt or any earlier
-// seg slice past fn's return for that segment. The scratch parameter is
-// unused on the destructive path and kept only for cross-platform
-// signature compatibility. Aborts and returns the first error from fn or
-// from per-segment construction.
-func SegmentSuperpacket(pkt Packet, fn func(seg []byte) error) error {
-	if !pkt.GSO.IsSuperpacket() {
-		return fn(pkt.Bytes)
-	}
-	switch pkt.GSO.Proto {
-	case GSOProtoTCP:
-		return virtio.SegmentTCP(pkt.Bytes, pkt.GSO.HdrLen, pkt.GSO.CsumStart, pkt.GSO.Size, fn)
-	case GSOProtoUDP:
-		return virtio.SegmentUDP(pkt.Bytes, pkt.GSO.HdrLen, pkt.GSO.CsumStart, pkt.GSO.Size, fn)
-	default:
-		return fmt.Errorf("unsupported gso proto: %d", pkt.GSO.Proto)
-	}
-}

overlay/tio/tun_linux_offload_test.go

@@ -1,794 +0,0 @@
-//go:build linux && !android && !e2e_testing
-// +build linux,!android,!e2e_testing
-
-package tio
-
-import (
-	"encoding/binary"
-	"os"
-	"testing"
-
-	"golang.org/x/sys/unix"
-	"gvisor.dev/gvisor/pkg/tcpip/checksum"
-
-	"github.com/slackhq/nebula/overlay/tio/virtio"
-)
-
-// testSegScratchSize is a generous segmentation scratch sized to fit any
-// of the synthetic TSO/USO superpackets these tests generate (one
-// worst-case 64 KiB superpacket plus replicated per-segment headers).
-const testSegScratchSize = 192 * 1024
-
-// verifyChecksum confirms that the one's-complement sum across `b`, seeded
-// with a folded pseudo-header sum, equals all-ones (valid).
-func verifyChecksum(b []byte, pseudo uint16) bool {
-	return checksum.Checksum(b, pseudo) == 0xffff
-}
-
-// segmentForTest is the test-only counterpart to the production
-// SegmentSuperpacket path. It handles GSO_NONE (with optional
-// finishChecksum) inline and dispatches GSO superpackets through
-// SegmentSuperpacket, draining each yielded segment into a
-// freshly-copied [][]byte slot so callers can iterate after the call
-// returns. Tests pre-set hdr.HdrLen correctly, so correctHdrLen is not
-// invoked here.
-func segmentForTest(pkt []byte, hdr virtio.Hdr, out *[][]byte, scratch []byte) error {
-	if hdr.GSOType == unix.VIRTIO_NET_HDR_GSO_NONE {
-		cp := append([]byte(nil), pkt...)
-		if hdr.Flags&unix.VIRTIO_NET_HDR_F_NEEDS_CSUM != 0 {
-			if err := virtio.FinishChecksum(cp, hdr); err != nil {
-				return err
-			}
-		}
-		*out = append(*out, cp)
-		return nil
-	}
-	proto, err := protoFromGSOType(hdr.GSOType)
-	if err != nil {
-		return err
-	}
-	gso := GSOInfo{
-		Size:      hdr.GSOSize,
-		HdrLen:    hdr.HdrLen,
-		CsumStart: hdr.CsumStart,
-		Proto:     proto,
-	}
-	return SegmentSuperpacket(Packet{Bytes: pkt, GSO: gso}, func(seg []byte) error {
-		*out = append(*out, append([]byte(nil), seg...))
-		return nil
-	})
-}
-
-// pseudoHeaderIPv4 returns the folded pseudo-header sum used to verify a
-// TCP/UDP segment's checksum in tests. src/dst are 4 bytes each.
-func pseudoHeaderIPv4(src, dst []byte, proto byte, l4Len int) uint16 {
-	s := uint32(checksum.Checksum(src, 0)) + uint32(checksum.Checksum(dst, 0))
-	s += uint32(proto) + uint32(l4Len)
-	s = (s & 0xffff) + (s >> 16)
-	s = (s & 0xffff) + (s >> 16)
-	return uint16(s)
-}
-
-// pseudoHeaderIPv6 returns the folded pseudo-header sum used to verify a
-// TCP/UDP segment's checksum in tests. src/dst are 16 bytes each.
-func pseudoHeaderIPv6(src, dst []byte, proto byte, l4Len int) uint16 {
-	s := uint32(checksum.Checksum(src, 0)) + uint32(checksum.Checksum(dst, 0))
-	s += uint32(l4Len>>16) + uint32(l4Len&0xffff) + uint32(proto)
-	s = (s & 0xffff) + (s >> 16)
-	s = (s & 0xffff) + (s >> 16)
-	return uint16(s)
-}
-
-// buildTSOv4 builds a synthetic IPv4/TCP TSO superpacket with a payload of
-// `payLen` bytes split at `mss`.
-func buildTSOv4(t *testing.T, payLen, mss int) ([]byte, virtio.Hdr) {
-	t.Helper()
-	const ipLen = 20
-	const tcpLen = 20
-	pkt := make([]byte, ipLen+tcpLen+payLen)
-
-	// IPv4 header
-	pkt[0] = 0x45 // version 4, IHL 5
-	// total length is meaningless for TSO but set it anyway
-	binary.BigEndian.PutUint16(pkt[2:4], uint16(ipLen+tcpLen+payLen))
-	binary.BigEndian.PutUint16(pkt[4:6], 0x4242) // original ID
-	pkt[8] = 64                                  // TTL
-	pkt[9] = unix.IPPROTO_TCP
-	copy(pkt[12:16], []byte{10, 0, 0, 1}) // src
-	copy(pkt[16:20], []byte{10, 0, 0, 2}) // dst
-
-	// TCP header
-	binary.BigEndian.PutUint16(pkt[20:22], 12345) // sport
-	binary.BigEndian.PutUint16(pkt[22:24], 80)    // dport
-	binary.BigEndian.PutUint32(pkt[24:28], 10000) // seq
-	binary.BigEndian.PutUint32(pkt[28:32], 20000) // ack
-	pkt[32] = 0x50                                // data offset 5 words
-	pkt[33] = 0x18                                // ACK | PSH
-	binary.BigEndian.PutUint16(pkt[34:36], 65535) // window
-
-	// payload
-	for i := 0; i < payLen; i++ {
-		pkt[ipLen+tcpLen+i] = byte(i & 0xff)
-	}
-
-	return pkt, virtio.Hdr{
-		Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-		GSOType:    unix.VIRTIO_NET_HDR_GSO_TCPV4,
-		HdrLen:     uint16(ipLen + tcpLen),
-		GSOSize:    uint16(mss),
-		CsumStart:  uint16(ipLen),
-		CsumOffset: 16,
-	}
-}
-
-func TestSegmentTCPv4(t *testing.T) {
-	const mss = 100
-	const numSeg = 3
-	pkt, hdr := buildTSOv4(t, mss*numSeg, mss)
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != numSeg {
-		t.Fatalf("expected %d segments, got %d", numSeg, len(out))
-	}
-
-	for i, seg := range out {
-		if len(seg) != 40+mss {
-			t.Errorf("seg %d: unexpected len %d", i, len(seg))
-		}
-		totalLen := binary.BigEndian.Uint16(seg[2:4])
-		if totalLen != uint16(40+mss) {
-			t.Errorf("seg %d: total_len=%d want %d", i, totalLen, 40+mss)
-		}
-		id := binary.BigEndian.Uint16(seg[4:6])
-		if id != 0x4242+uint16(i) {
-			t.Errorf("seg %d: ip id=%#x want %#x", i, id, 0x4242+uint16(i))
-		}
-		seq := binary.BigEndian.Uint32(seg[24:28])
-		wantSeq := uint32(10000 + i*mss)
-		if seq != wantSeq {
-			t.Errorf("seg %d: seq=%d want %d", i, seq, wantSeq)
-		}
-		flags := seg[33]
-		wantFlags := byte(0x10) // ACK only, PSH cleared
-		if i == numSeg-1 {
-			wantFlags = 0x18 // ACK | PSH preserved on last
-		}
-		if flags != wantFlags {
-			t.Errorf("seg %d: flags=%#x want %#x", i, flags, wantFlags)
-		}
-		// IPv4 header checksum must verify against itself.
-		if !verifyChecksum(seg[:20], 0) {
-			t.Errorf("seg %d: bad IPv4 header checksum", i)
-		}
-		// TCP checksum must verify against the pseudo-header.
-		psum := pseudoHeaderIPv4(seg[12:16], seg[16:20], unix.IPPROTO_TCP, 20+mss)
-		if !verifyChecksum(seg[20:], psum) {
-			t.Errorf("seg %d: bad TCP checksum", i)
-		}
-	}
-}
-
-func TestSegmentTCPv4OddTail(t *testing.T) {
-	// Payload of 250 bytes with MSS 100 → segments of 100, 100, 50.
-	pkt, hdr := buildTSOv4(t, 250, 100)
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != 3 {
-		t.Fatalf("want 3 segments, got %d", len(out))
-	}
-	wantPayLens := []int{100, 100, 50}
-	for i, seg := range out {
-		if len(seg)-40 != wantPayLens[i] {
-			t.Errorf("seg %d: pay len %d want %d", i, len(seg)-40, wantPayLens[i])
-		}
-		if !verifyChecksum(seg[:20], 0) {
-			t.Errorf("seg %d: bad IPv4 header checksum", i)
-		}
-		psum := pseudoHeaderIPv4(seg[12:16], seg[16:20], unix.IPPROTO_TCP, 20+wantPayLens[i])
-		if !verifyChecksum(seg[20:], psum) {
-			t.Errorf("seg %d: bad TCP checksum", i)
-		}
-	}
-}
-
-func TestSegmentTCPv6(t *testing.T) {
-	const ipLen = 40
-	const tcpLen = 20
-	const mss = 120
-	const numSeg = 2
-	payLen := mss * numSeg
-	pkt := make([]byte, ipLen+tcpLen+payLen)
-
-	// IPv6 header
-	pkt[0] = 0x60 // version 6
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(tcpLen+payLen))
-	pkt[6] = unix.IPPROTO_TCP
-	pkt[7] = 64
-	// src/dst fe80::1 / fe80::2
-	pkt[8] = 0xfe
-	pkt[9] = 0x80
-	pkt[23] = 1
-	pkt[24] = 0xfe
-	pkt[25] = 0x80
-	pkt[39] = 2
-
-	// TCP header
-	binary.BigEndian.PutUint16(pkt[40:42], 12345)
-	binary.BigEndian.PutUint16(pkt[42:44], 80)
-	binary.BigEndian.PutUint32(pkt[44:48], 7)
-	binary.BigEndian.PutUint32(pkt[48:52], 99)
-	pkt[52] = 0x50
-	pkt[53] = 0x19 // FIN | ACK | PSH — exercise FIN clearing too
-	binary.BigEndian.PutUint16(pkt[54:56], 65535)
-
-	for i := 0; i < payLen; i++ {
-		pkt[ipLen+tcpLen+i] = byte(i)
-	}
-
-	hdr := virtio.Hdr{
-		Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-		GSOType:    unix.VIRTIO_NET_HDR_GSO_TCPV6,
-		HdrLen:     uint16(ipLen + tcpLen),
-		GSOSize:    uint16(mss),
-		CsumStart:  uint16(ipLen),
-		CsumOffset: 16,
-	}
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != numSeg {
-		t.Fatalf("want %d segments, got %d", numSeg, len(out))
-	}
-
-	for i, seg := range out {
-		if len(seg) != ipLen+tcpLen+mss {
-			t.Errorf("seg %d: len %d want %d", i, len(seg), ipLen+tcpLen+mss)
-		}
-		pl := binary.BigEndian.Uint16(seg[4:6])
-		if pl != uint16(tcpLen+mss) {
-			t.Errorf("seg %d: payload_length=%d want %d", i, pl, tcpLen+mss)
-		}
-		seq := binary.BigEndian.Uint32(seg[44:48])
-		if seq != uint32(7+i*mss) {
-			t.Errorf("seg %d: seq=%d want %d", i, seq, 7+i*mss)
-		}
-		flags := seg[53]
-		// Original flags = 0x19 (FIN|ACK|PSH). FIN(0x01)+PSH(0x08) should be
-		// cleared on all but the last; ACK(0x10) always preserved.
-		wantFlags := byte(0x10)
-		if i == numSeg-1 {
-			wantFlags = 0x19
-		}
-		if flags != wantFlags {
-			t.Errorf("seg %d: flags=%#x want %#x", i, flags, wantFlags)
-		}
-		psum := pseudoHeaderIPv6(seg[8:24], seg[24:40], unix.IPPROTO_TCP, tcpLen+mss)
-		if !verifyChecksum(seg[ipLen:], psum) {
-			t.Errorf("seg %d: bad TCP checksum", i)
-		}
-	}
-}
-
-func TestSegmentGSONonePassesThrough(t *testing.T) {
-	pkt, hdr := buildTSOv4(t, 100, 100)
-	hdr.GSOType = unix.VIRTIO_NET_HDR_GSO_NONE
-	hdr.Flags = 0 // no NEEDS_CSUM, leave packet untouched
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != 1 {
-		t.Fatalf("want 1 segment, got %d", len(out))
-	}
-	if len(out[0]) != len(pkt) {
-		t.Fatalf("unexpected length: %d vs %d", len(out[0]), len(pkt))
-	}
-}
-
-// TestSegmentRejectsLegacyUDPGSO ensures the legacy GSO_UDP (UFO) marker is
-// still rejected; only modern GSO_UDP_L4 (USO) is supported.
-func TestSegmentRejectsLegacyUDPGSO(t *testing.T) {
-	hdr := virtio.Hdr{GSOType: unix.VIRTIO_NET_HDR_GSO_UDP}
-	var out [][]byte
-	if err := segmentForTest(nil, hdr, &out, nil); err == nil {
-		t.Fatalf("expected rejection for legacy UDP GSO")
-	}
-}
-
-// buildUSOv4 builds a synthetic IPv4/UDP USO superpacket with payload of
-// payLen bytes, segmented at gsoSize.
-func buildUSOv4(t *testing.T, payLen, gsoSize int) ([]byte, virtio.Hdr) {
-	t.Helper()
-	const ipLen = 20
-	const udpLen = 8
-	pkt := make([]byte, ipLen+udpLen+payLen)
-
-	// IPv4 header
-	pkt[0] = 0x45 // version 4, IHL 5
-	binary.BigEndian.PutUint16(pkt[2:4], uint16(ipLen+udpLen+payLen))
-	binary.BigEndian.PutUint16(pkt[4:6], 0x4242)
-	pkt[8] = 64
-	pkt[9] = unix.IPPROTO_UDP
-	copy(pkt[12:16], []byte{10, 0, 0, 1})
-	copy(pkt[16:20], []byte{10, 0, 0, 2})
-
-	// UDP header (length + checksum filled in per segment by segmentUDPYield)
-	binary.BigEndian.PutUint16(pkt[20:22], 12345) // sport
-	binary.BigEndian.PutUint16(pkt[22:24], 53)    // dport
-
-	for i := 0; i < payLen; i++ {
-		pkt[ipLen+udpLen+i] = byte(i & 0xff)
-	}
-
-	return pkt, virtio.Hdr{
-		Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-		GSOType:    unix.VIRTIO_NET_HDR_GSO_UDP_L4,
-		HdrLen:     uint16(ipLen + udpLen),
-		GSOSize:    uint16(gsoSize),
-		CsumStart:  uint16(ipLen),
-		CsumOffset: 6,
-	}
-}
-
-func TestSegmentUDPv4(t *testing.T) {
-	const gso = 100
-	const numSeg = 3
-	pkt, hdr := buildUSOv4(t, gso*numSeg, gso)
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != numSeg {
-		t.Fatalf("expected %d segments, got %d", numSeg, len(out))
-	}
-
-	for i, seg := range out {
-		if len(seg) != 28+gso {
-			t.Errorf("seg %d: len %d want %d", i, len(seg), 28+gso)
-		}
-		totalLen := binary.BigEndian.Uint16(seg[2:4])
-		if totalLen != uint16(28+gso) {
-			t.Errorf("seg %d: total_len=%d want %d", i, totalLen, 28+gso)
-		}
-		// kernel UDP-GSO does NOT bump the IPv4 ID across segments; every
-		// segment carries the same ID as the seed.
-		id := binary.BigEndian.Uint16(seg[4:6])
-		if id != 0x4242 {
-			t.Errorf("seg %d: ip id=%#x want %#x", i, id, 0x4242)
-		}
-		udpLen := binary.BigEndian.Uint16(seg[24:26])
-		if udpLen != uint16(8+gso) {
-			t.Errorf("seg %d: udp len=%d want %d", i, udpLen, 8+gso)
-		}
-		if !verifyChecksum(seg[:20], 0) {
-			t.Errorf("seg %d: bad IPv4 header checksum", i)
-		}
-		psum := pseudoHeaderIPv4(seg[12:16], seg[16:20], unix.IPPROTO_UDP, 8+gso)
-		if !verifyChecksum(seg[20:], psum) {
-			t.Errorf("seg %d: bad UDP checksum", i)
-		}
-	}
-}
-
-func TestSegmentUDPv4OddTail(t *testing.T) {
-	// 250 bytes payload, gsoSize=100 → segments of 100, 100, 50.
-	pkt, hdr := buildUSOv4(t, 250, 100)
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != 3 {
-		t.Fatalf("want 3 segments, got %d", len(out))
-	}
-	wantPay := []int{100, 100, 50}
-	for i, seg := range out {
-		if len(seg)-28 != wantPay[i] {
-			t.Errorf("seg %d: pay len %d want %d", i, len(seg)-28, wantPay[i])
-		}
-		udpLen := binary.BigEndian.Uint16(seg[24:26])
-		if udpLen != uint16(8+wantPay[i]) {
-			t.Errorf("seg %d: udp len=%d want %d", i, udpLen, 8+wantPay[i])
-		}
-		if !verifyChecksum(seg[:20], 0) {
-			t.Errorf("seg %d: bad IPv4 header checksum", i)
-		}
-		psum := pseudoHeaderIPv4(seg[12:16], seg[16:20], unix.IPPROTO_UDP, 8+wantPay[i])
-		if !verifyChecksum(seg[20:], psum) {
-			t.Errorf("seg %d: bad UDP checksum", i)
-		}
-	}
-}
-
-func TestSegmentUDPv6(t *testing.T) {
-	const ipLen = 40
-	const udpLen = 8
-	const gso = 120
-	const numSeg = 2
-	payLen := gso * numSeg
-	pkt := make([]byte, ipLen+udpLen+payLen)
-
-	// IPv6 header
-	pkt[0] = 0x60
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(udpLen+payLen))
-	pkt[6] = unix.IPPROTO_UDP
-	pkt[7] = 64
-	pkt[8] = 0xfe
-	pkt[9] = 0x80
-	pkt[23] = 1
-	pkt[24] = 0xfe
-	pkt[25] = 0x80
-	pkt[39] = 2
-
-	binary.BigEndian.PutUint16(pkt[40:42], 12345)
-	binary.BigEndian.PutUint16(pkt[42:44], 53)
-
-	for i := 0; i < payLen; i++ {
-		pkt[ipLen+udpLen+i] = byte(i)
-	}
-
-	hdr := virtio.Hdr{
-		Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-		GSOType:    unix.VIRTIO_NET_HDR_GSO_UDP_L4,
-		HdrLen:     uint16(ipLen + udpLen),
-		GSOSize:    uint16(gso),
-		CsumStart:  uint16(ipLen),
-		CsumOffset: 6,
-	}
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != numSeg {
-		t.Fatalf("want %d segments, got %d", numSeg, len(out))
-	}
-
-	for i, seg := range out {
-		if len(seg) != ipLen+udpLen+gso {
-			t.Errorf("seg %d: len %d want %d", i, len(seg), ipLen+udpLen+gso)
-		}
-		pl := binary.BigEndian.Uint16(seg[4:6])
-		if pl != uint16(udpLen+gso) {
-			t.Errorf("seg %d: payload_length=%d want %d", i, pl, udpLen+gso)
-		}
-		ul := binary.BigEndian.Uint16(seg[ipLen+4 : ipLen+6])
-		if ul != uint16(udpLen+gso) {
-			t.Errorf("seg %d: udp len=%d want %d", i, ul, udpLen+gso)
-		}
-		psum := pseudoHeaderIPv6(seg[8:24], seg[24:40], unix.IPPROTO_UDP, udpLen+gso)
-		if !verifyChecksum(seg[ipLen:], psum) {
-			t.Errorf("seg %d: bad UDP checksum", i)
-		}
-	}
-}
-
-// TestSegmentUDPCEPropagates confirms IP-level CE marks on the seed appear on
-// every segment. UDP has no transport-level CWR/ECE: the IP TOS/TC byte is
-// copied verbatim into every segment by the segment-prefix copy.
-func TestSegmentUDPCEPropagates(t *testing.T) {
-	pkt, hdr := buildUSOv4(t, 200, 100)
-	pkt[1] = 0x03 // CE codepoint in IP-ECN
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != 2 {
-		t.Fatalf("want 2 segments, got %d", len(out))
-	}
-	for i, seg := range out {
-		if seg[1]&0x03 != 0x03 {
-			t.Errorf("seg %d: CE missing (tos=%#x)", i, seg[1])
-		}
-		if !verifyChecksum(seg[:20], 0) {
-			t.Errorf("seg %d: bad IPv4 header checksum", i)
-		}
-	}
-}
-
-// TestSegmentTCPCwrFirstSegmentOnly confirms RFC 3168 §6.1.2: when a TSO
-// burst's seed has CWR set, only the first emitted segment carries CWR.
-// ECE is preserved on every segment (different signal, persistent state).
-func TestSegmentTCPCwrFirstSegmentOnly(t *testing.T) {
-	const mss = 100
-	const numSeg = 3
-	pkt, hdr := buildTSOv4(t, mss*numSeg, mss)
-	// Seed flags: CWR | ECE | ACK | PSH.
-	pkt[33] = 0x80 | 0x40 | 0x10 | 0x08
-
-	scratch := make([]byte, testSegScratchSize)
-	var out [][]byte
-	if err := segmentForTest(pkt, hdr, &out, scratch); err != nil {
-		t.Fatalf("segmentForTest: %v", err)
-	}
-	if len(out) != numSeg {
-		t.Fatalf("expected %d segments, got %d", numSeg, len(out))
-	}
-	for i, seg := range out {
-		flags := seg[33]
-		hasCwr := flags&0x80 != 0
-		hasEce := flags&0x40 != 0
-		hasPsh := flags&0x08 != 0
-		wantCwr := i == 0
-		wantPsh := i == numSeg-1
-		if hasCwr != wantCwr {
-			t.Errorf("seg %d: CWR=%v want %v (flags=%#x)", i, hasCwr, wantCwr, flags)
-		}
-		if !hasEce {
-			t.Errorf("seg %d: ECE missing (flags=%#x)", i, flags)
-		}
-		if hasPsh != wantPsh {
-			t.Errorf("seg %d: PSH=%v want %v (flags=%#x)", i, hasPsh, wantPsh, flags)
-		}
-		// IP and TCP checksums must still verify after the flag rewrite.
-		if !verifyChecksum(seg[:20], 0) {
-			t.Errorf("seg %d: bad IPv4 header checksum", i)
-		}
-		psum := pseudoHeaderIPv4(seg[12:16], seg[16:20], unix.IPPROTO_TCP, 20+mss)
-		if !verifyChecksum(seg[20:], psum) {
-			t.Errorf("seg %d: bad TCP checksum", i)
-		}
-	}
-}
-
-func BenchmarkSegmentTCPv4(b *testing.B) {
-	sizes := []struct {
-		name   string
-		payLen int
-		mss    int
-	}{
-		{"64KiB_MSS1460", 65000, 1460},
-		{"16KiB_MSS1460", 16384, 1460},
-		{"4KiB_MSS1460", 4096, 1460},
-	}
-	for _, sz := range sizes {
-		b.Run(sz.name, func(b *testing.B) {
-			const ipLen = 20
-			const tcpLen = 20
-			pkt := make([]byte, ipLen+tcpLen+sz.payLen)
-			pkt[0] = 0x45
-			binary.BigEndian.PutUint16(pkt[2:4], uint16(ipLen+tcpLen+sz.payLen))
-			binary.BigEndian.PutUint16(pkt[4:6], 0x4242)
-			pkt[8] = 64
-			pkt[9] = unix.IPPROTO_TCP
-			copy(pkt[12:16], []byte{10, 0, 0, 1})
-			copy(pkt[16:20], []byte{10, 0, 0, 2})
-			binary.BigEndian.PutUint16(pkt[20:22], 12345)
-			binary.BigEndian.PutUint16(pkt[22:24], 80)
-			binary.BigEndian.PutUint32(pkt[24:28], 10000)
-			binary.BigEndian.PutUint32(pkt[28:32], 20000)
-			pkt[32] = 0x50
-			pkt[33] = 0x18
-			binary.BigEndian.PutUint16(pkt[34:36], 65535)
-			for i := 0; i < sz.payLen; i++ {
-				pkt[ipLen+tcpLen+i] = byte(i)
-			}
-			hdr := virtio.Hdr{
-				Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-				GSOType:    unix.VIRTIO_NET_HDR_GSO_TCPV4,
-				HdrLen:     uint16(ipLen + tcpLen),
-				GSOSize:    uint16(sz.mss),
-				CsumStart:  uint16(ipLen),
-				CsumOffset: 16,
-			}
-
-			scratch := make([]byte, testSegScratchSize)
-			out := make([][]byte, 0, 64)
-
-			// SegmentSuperpacket consumes its input destructively; restore
-			// pkt from a master copy each iteration. The restore mirrors the
-			// kernel→userspace copy that hands a fresh GSO blob to the
-			// segmenter in production, so it's representative cost rather
-			// than bench overhead.
-			master := append([]byte(nil), pkt...)
-			work := make([]byte, len(pkt))
-
-			b.SetBytes(int64(len(pkt)))
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
-				copy(work, master)
-				out = out[:0]
-				if err := segmentForTest(work, hdr, &out, scratch); err != nil {
-					b.Fatal(err)
-				}
-			}
-		})
-	}
-}
-
-// TestTunFileWriteVnetHdrNoAlloc verifies the IFF_VNET_HDR fast-path write is
-// allocation-free. We write to /dev/null so every call succeeds synchronously.
-func TestTunFileWriteVnetHdrNoAlloc(t *testing.T) {
-	fd, err := unix.Open("/dev/null", os.O_WRONLY, 0)
-	if err != nil {
-		t.Fatalf("open /dev/null: %v", err)
-	}
-	t.Cleanup(func() { _ = unix.Close(fd) })
-
-	tf := &Offload{fd: fd}
-
-	payload := make([]byte, 1400)
-	// Warm up (first call may trigger one-time internal allocations elsewhere).
-	if _, err := tf.Write(payload); err != nil {
-		t.Fatalf("Write: %v", err)
-	}
-
-	allocs := testing.AllocsPerRun(1000, func() {
-		if _, err := tf.Write(payload); err != nil {
-			t.Fatalf("Write: %v", err)
-		}
-	})
-	if allocs != 0 {
-		t.Fatalf("Write allocated %.1f times per call, want 0", allocs)
-	}
-}
-
-// buildTSOv6 builds a synthetic IPv6/TCP TSO superpacket with payLen bytes
-// of payload, segmented at gso. Returns the packet bytes only; the
-// virtio_net_hdr is the caller's responsibility.
-func buildTSOv6(payLen, gso int) []byte {
-	const ipLen = 40
-	const tcpLen = 20
-	pkt := make([]byte, ipLen+tcpLen+payLen)
-
-	pkt[0] = 0x60 // version 6
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(tcpLen+payLen))
-	pkt[6] = unix.IPPROTO_TCP
-	pkt[7] = 64
-	pkt[8] = 0xfe
-	pkt[9] = 0x80
-	pkt[23] = 1
-	pkt[24] = 0xfe
-	pkt[25] = 0x80
-	pkt[39] = 2
-
-	binary.BigEndian.PutUint16(pkt[40:42], 12345)
-	binary.BigEndian.PutUint16(pkt[42:44], 80)
-	binary.BigEndian.PutUint32(pkt[44:48], 7)
-	binary.BigEndian.PutUint32(pkt[48:52], 99)
-	pkt[52] = 0x50
-	pkt[53] = 0x10 // ACK only
-	binary.BigEndian.PutUint16(pkt[54:56], 65535)
-
-	for i := 0; i < payLen; i++ {
-		pkt[ipLen+tcpLen+i] = byte(i)
-	}
-	return pkt
-}
-
-// TestDecodeReadFitsMaxTSOAtDrainThreshold proves the rxBuf sizing is
-// correct: when rxOff is at the maximum value the drain headroom check
-// allows, decodeRead must still be able to absorb a worst-case 64KiB
-// TSO superpacket without dropping the burst. With segmentation deferred
-// to encrypt time, decodeRead writes only the kernel-supplied bytes into
-// rxBuf, so the size requirement is just "fit one worst-case input."
-//
-// Regression history: in a prior layout the rx buffer doubled as the
-// segmentation output, a near-threshold drain read returned "scratch too
-// small", the whole 45-segment TSO burst was dropped, and the remote's TCP
-// fast-retransmit collapsed cwnd. Keeping this test in the new layout
-// guards against re-introducing a drain headroom shortfall.
-func TestDecodeReadFitsMaxTSOAtDrainThreshold(t *testing.T) {
-	const ipv6HdrLen = 40
-	const tcpHdrLen = 20
-	const headerLen = ipv6HdrLen + tcpHdrLen
-	// Maximum TUN read body. The tunReadBufSize cap on readv's body iovec
-	// is what bounds the kernel's superpacket length.
-	pktLen := tunReadBufSize
-	payLen := pktLen - headerLen
-	const targetSegs = 64
-	gsoSize := (payLen + targetSegs - 1) / targetSegs
-
-	pkt := buildTSOv6(payLen, gsoSize)
-	if len(pkt) != pktLen {
-		t.Fatalf("buildTSOv6 produced %d bytes, want %d", len(pkt), pktLen)
-	}
-
-	o := &Offload{
-		rxBuf: make([]byte, tunRxBufCap),
-	}
-	// rxOff at the maximum value the drain headroom check permits before
-	// it would refuse another read. Any drain-time read up to this
-	// threshold MUST still process correctly.
-	o.rxOff = tunRxBufCap - tunRxBufSize
-
-	// Stage the body in rxBuf as if readv(2) just placed it there.
-	copy(o.rxBuf[o.rxOff:], pkt)
-
-	// Encode the matching virtio_net_hdr.
-	hdr := virtio.Hdr{
-		Flags:      unix.VIRTIO_NET_HDR_F_NEEDS_CSUM,
-		GSOType:    unix.VIRTIO_NET_HDR_GSO_TCPV6,
-		HdrLen:     uint16(headerLen),
-		GSOSize:    uint16(gsoSize),
-		CsumStart:  uint16(ipv6HdrLen),
-		CsumOffset: 16,
-	}
-	hdr.Encode(o.readVnetScratch[:])
-
-	startRxOff := o.rxOff
-	if err := o.decodeRead(pktLen); err != nil {
-		t.Fatalf("decodeRead at drain threshold returned %v — rxBuf sizing regression: "+
-			"tunRxBufSize=%d must hold one worst-case input (%d)",
-			err, tunRxBufSize, pktLen)
-	}
-
-	if len(o.pending) != 1 {
-		t.Fatalf("got %d packets, want 1 superpacket entry", len(o.pending))
-	}
-	got := o.pending[0]
-	if !got.GSO.IsSuperpacket() {
-		t.Fatalf("expected superpacket GSO metadata, got %+v", got.GSO)
-	}
-	if got.GSO.Proto != GSOProtoTCP {
-		t.Errorf("GSO.Proto=%d want TCP", got.GSO.Proto)
-	}
-	if got.GSO.Size != uint16(gsoSize) {
-		t.Errorf("GSO.Size=%d want %d", got.GSO.Size, gsoSize)
-	}
-	if got.GSO.HdrLen != uint16(headerLen) {
-		t.Errorf("GSO.HdrLen=%d want %d", got.GSO.HdrLen, headerLen)
-	}
-	if got.GSO.CsumStart != uint16(ipv6HdrLen) {
-		t.Errorf("GSO.CsumStart=%d want %d", got.GSO.CsumStart, ipv6HdrLen)
-	}
-	if len(got.Bytes) != pktLen {
-		t.Errorf("len(Bytes)=%d want %d", len(got.Bytes), pktLen)
-	}
-
-	// rxOff advances exactly by the kernel-supplied body length — no
-	// segmentation output to account for any more.
-	if o.rxOff != startRxOff+pktLen {
-		t.Errorf("rxOff=%d want %d", o.rxOff, startRxOff+pktLen)
-	}
-	if o.rxOff > tunRxBufCap {
-		t.Fatalf("rxOff=%d overran rxBuf (cap=%d)", o.rxOff, tunRxBufCap)
-	}
-
-	// Validate that segmenting the returned superpacket reproduces the
-	// expected per-segment IPv6 payload length and TCP checksum.
-	wantSegs := (payLen + gsoSize - 1) / gsoSize
-	gotSegs := 0
-	if err := SegmentSuperpacket(got, func(seg []byte) error {
-		defer func() { gotSegs++ }()
-		if len(seg) < headerLen+1 {
-			t.Errorf("seg %d too short: %d", gotSegs, len(seg))
-			return nil
-		}
-		if seg[0]>>4 != 6 {
-			t.Errorf("seg %d: bad IP version %#x", gotSegs, seg[0])
-		}
-		segPay := len(seg) - headerLen
-		gotPL := binary.BigEndian.Uint16(seg[4:6])
-		if gotPL != uint16(tcpHdrLen+segPay) {
-			t.Errorf("seg %d: payload_len=%d want %d", gotSegs, gotPL, tcpHdrLen+segPay)
-		}
-		psum := pseudoHeaderIPv6(seg[8:24], seg[24:40], unix.IPPROTO_TCP, tcpHdrLen+segPay)
-		if !verifyChecksum(seg[ipv6HdrLen:], psum) {
-			t.Errorf("seg %d: bad TCP checksum", gotSegs)
-		}
-		return nil
-	}); err != nil {
-		t.Fatalf("SegmentSuperpacket: %v", err)
-	}
-	if gotSegs != wantSegs {
-		t.Fatalf("got %d segments, want %d", gotSegs, wantSegs)
-	}
-}

overlay/tio/virtio/header_linux.go

@@ -1,43 +0,0 @@
-//go:build linux && !android
-// +build linux,!android
-
-package virtio
-
-import "encoding/binary"
-
-// Size is the on-wire length of struct virtio_net_hdr the kernel
-// prepends/expects on a TUN opened with IFF_VNET_HDR (TUNSETVNETHDRSZ
-// not set).
-const Size = 10
-
-// Hdr is the Go view of the legacy virtio_net_hdr.
-type Hdr struct {
-	Flags      uint8
-	GSOType    uint8
-	HdrLen     uint16
-	GSOSize    uint16
-	CsumStart  uint16
-	CsumOffset uint16
-}
-
-// Decode reads a virtio_net_hdr in host byte order (TUN default; we never
-// call TUNSETVNETLE so the kernel matches our endianness).
-func (h *Hdr) Decode(b []byte) {
-	h.Flags = b[0]
-	h.GSOType = b[1]
-	h.HdrLen = binary.NativeEndian.Uint16(b[2:4])
-	h.GSOSize = binary.NativeEndian.Uint16(b[4:6])
-	h.CsumStart = binary.NativeEndian.Uint16(b[6:8])
-	h.CsumOffset = binary.NativeEndian.Uint16(b[8:10])
-}
-
-// Encode is the inverse of Decode: writes the virtio_net_hdr fields into b
-// (must be at least Size bytes). Used to emit a TSO superpacket on egress.
-func (h *Hdr) Encode(b []byte) {
-	b[0] = h.Flags
-	b[1] = h.GSOType
-	binary.NativeEndian.PutUint16(b[2:4], h.HdrLen)
-	binary.NativeEndian.PutUint16(b[4:6], h.GSOSize)
-	binary.NativeEndian.PutUint16(b[6:8], h.CsumStart)
-	binary.NativeEndian.PutUint16(b[8:10], h.CsumOffset)
-}

overlay/tio/virtio/segment_linux.go

@@ -1,402 +0,0 @@
-//go:build linux && !android
-// +build linux,!android
-
-// Package virtio implements the pure validation, header-correction, and
-// per-segment slicing logic for kernel-supplied TSO/USO superpackets on
-// IFF_VNET_HDR TUN devices. It is FD-free and depends only on the byte
-// layout of the virtio_net_hdr and the IP/TCP/UDP headers it describes,
-// so it can be unit-tested in isolation from the tio Queue runtime.
-package virtio
-
-import (
-	"encoding/binary"
-	"errors"
-	"fmt"
-
-	"golang.org/x/sys/unix"
-
-	"github.com/slackhq/nebula/overlay/checksum"
-)
-
-// Protocol header size bounds used to validate / cap kernel-supplied offsets.
-const (
-	ipv4HeaderMinLen = 20 // IHL=5, no options
-	ipv4HeaderMaxLen = 60 // IHL=15, max options
-	ipv6FixedLen     = 40 // IPv6 base header; extensions would extend this
-	tcpHeaderMinLen  = 20 // data-offset=5, no options
-	tcpHeaderMaxLen  = 60 // data-offset=15, max options
-)
-
-// Byte offsets inside an IPv4 header.
-const (
-	ipv4TotalLenOff = 2
-	ipv4IDOff       = 4
-	ipv4ChecksumOff = 10
-	ipv4SrcOff      = 12
-	ipv4AddrsEnd    = 20 // end of dst address (ipv4SrcOff + 2*4)
-)
-
-// Byte offsets inside an IPv6 header.
-const (
-	ipv6PayloadLenOff = 4
-	ipv6SrcOff        = 8
-	ipv6AddrsEnd      = 40 // end of dst address (ipv6SrcOff + 2*16)
-)
-
-// Byte offsets inside a TCP header (relative to its start, i.e. csumStart).
-const (
-	tcpSeqOff      = 4
-	tcpDataOffOff  = 12 // upper nibble is header len in 32-bit words
-	tcpFlagsOff    = 13
-	tcpChecksumOff = 16
-)
-
-// UDP header is fixed at 8 bytes: {sport, dport, length, checksum}.
-const (
-	udpHeaderLen   = 8
-	udpLengthOff   = 4
-	udpChecksumOff = 6
-)
-
-// tcpFinPshMask is cleared on every segment except the last of a TSO burst.
-const tcpFinPshMask = 0x09 // FIN(0x01) | PSH(0x08)
-
-// tcpCwrFlag is cleared on every segment except the first. Per RFC 3168
-// §6.1.2 the CWR bit signals a one-shot transition (the sender just halved
-// its window) and must appear on the first segment of a TSO burst only.
-const tcpCwrFlag = 0x80
-
-// CheckValid rejects packets whose virtio_net_hdr/IP combination would
-// cause a downstream miscompute. The TUN should never emit RSC_INFO and
-// the GSO type must agree with the IP version nibble.
-func CheckValid(pkt []byte, hdr Hdr) error {
-	// When RSC_INFO is set the csum_start/csum_offset fields are repurposed to
-	// carry coalescing info rather than checksum offsets. A TUN writing via
-	// IFF_VNET_HDR should never emit this, but if it did we would silently
-	// miscompute the segment checksums — refuse the packet instead.
-	if hdr.Flags&unix.VIRTIO_NET_HDR_F_RSC_INFO != 0 {
-		return fmt.Errorf("virtio RSC_INFO flag not supported on TUN reads")
-	}
-	if len(pkt) < ipv4HeaderMinLen {
-		return fmt.Errorf("packet too short")
-	}
-	ipVersion := pkt[0] >> 4
-	switch hdr.GSOType {
-	case unix.VIRTIO_NET_HDR_GSO_TCPV4:
-		if ipVersion != 4 {
-			return fmt.Errorf("invalid IP version %d for GSO type %d", ipVersion, hdr.GSOType)
-		}
-	case unix.VIRTIO_NET_HDR_GSO_TCPV6:
-		if ipVersion != 6 {
-			return fmt.Errorf("invalid IP version %d for GSO type %d", ipVersion, hdr.GSOType)
-		}
-	case unix.VIRTIO_NET_HDR_GSO_UDP_L4:
-		// USO carries either v4 or v6; the leading nibble disambiguates.
-		if !(ipVersion == 4 || ipVersion == 6) {
-			return fmt.Errorf("invalid IP version %d for GSO type %d", ipVersion, hdr.GSOType)
-		}
-	default:
-		if !(ipVersion == 6 || ipVersion == 4) {
-			return fmt.Errorf("invalid IP version %d for GSO type %d", ipVersion, hdr.GSOType)
-		}
-	}
-
-	return nil
-}
-
-// CorrectHdrLen rewrites hdr.HdrLen based on the actual transport header
-// length read out of pkt. The kernel's hdr.HdrLen on the FORWARD path can
-// be the length of the entire first packet, so we don't trust it.
-func CorrectHdrLen(pkt []byte, hdr *Hdr) error {
-	// Thank you wireguard-go for documenting these edge-cases
-	// Don't trust hdr.hdrLen from the kernel as it can be equal to the length
-	// of the entire first packet when the kernel is handling it as part of a
-	// FORWARD path. Instead, parse the transport header length and add it onto
-	// csumStart, which is synonymous for IP header length.
-
-	if hdr.GSOType == unix.VIRTIO_NET_HDR_GSO_UDP_L4 {
-		hdr.HdrLen = hdr.CsumStart + 8
-	} else {
-		if len(pkt) <= int(hdr.CsumStart+tcpDataOffOff) {
-			return errors.New("packet is too short")
-		}
-
-		tcpHLen := uint16(pkt[hdr.CsumStart+tcpDataOffOff] >> 4 * 4)
-		if tcpHLen < 20 || tcpHLen > 60 {
-			// A TCP header must be between 20 and 60 bytes in length.
-			return fmt.Errorf("tcp header len is invalid: %d", tcpHLen)
-		}
-		hdr.HdrLen = hdr.CsumStart + tcpHLen
-	}
-
-	if len(pkt) < int(hdr.HdrLen) {
-		return fmt.Errorf("length of packet (%d) < virtioNetHdr.HdrLen (%d)", len(pkt), hdr.HdrLen)
-	}
-
-	if hdr.HdrLen < hdr.CsumStart {
-		return fmt.Errorf("virtioNetHdr.HdrLen (%d) < virtioNetHdr.CsumStart (%d)", hdr.HdrLen, hdr.CsumStart)
-	}
-	cSumAt := int(hdr.CsumStart + hdr.CsumStart)
-	if cSumAt+1 >= len(pkt) {
-		return fmt.Errorf("end of checksum offset (%d) exceeds packet length (%d)", cSumAt+1, len(pkt))
-	}
-	return nil
-}
-
-// SegmentTCP walks a TSO superpacket pkt, yielding each segment as a
-// slice into pkt itself. Per-segment plaintext is laid out by sliding a
-// freshly-patched copy of the L3+L4 header into pkt at offset i*gsoSize,
-// where it sits immediately before that segment's payload chunk in the
-// original buffer. The slide is destructive: iter i's header write overwrites
-// the last hdrLen bytes of seg_{i-1}'s payload, which is dead by the time
-// the next iteration begins. pkt is consumed by this call and must not be
-// inspected by the caller after the final yield.
-func SegmentTCP(pkt []byte, hdrLenU, csumStartU, gsoSizeU uint16, yield func(seg []byte) error) error {
-	if gsoSizeU == 0 {
-		return fmt.Errorf("gso_size is zero")
-	}
-	if csumStartU == 0 {
-		return fmt.Errorf("csum_start is zero")
-	}
-
-	headerLen := int(hdrLenU)
-	csumStart := int(csumStartU)
-	isV4 := pkt[0]>>4 == 4
-
-	tcpHdrLen := int(pkt[csumStart+tcpDataOffOff]>>4) * 4
-	payLen := len(pkt) - headerLen
-	gsoSize := int(gsoSizeU)
-	numSeg := (payLen + gsoSize - 1) / gsoSize
-	if numSeg == 0 {
-		numSeg = 1
-	}
-
-	origSeq := binary.BigEndian.Uint32(pkt[csumStart+tcpSeqOff : csumStart+tcpSeqOff+4])
-	origFlags := pkt[csumStart+tcpFlagsOff]
-
-	var tmp [tcpHeaderMaxLen]byte
-	copy(tmp[:tcpHdrLen], pkt[csumStart:headerLen])
-	tmp[tcpSeqOff], tmp[tcpSeqOff+1], tmp[tcpSeqOff+2], tmp[tcpSeqOff+3] = 0, 0, 0, 0
-	tmp[tcpFlagsOff] = 0
-	tmp[tcpChecksumOff], tmp[tcpChecksumOff+1] = 0, 0
-	baseTcpHdrSum := uint32(checksum.Checksum(tmp[:tcpHdrLen], 0))
-
-	var baseProtoSum uint32
-	if isV4 {
-		baseProtoSum = uint32(checksum.Checksum(pkt[ipv4SrcOff:ipv4AddrsEnd], 0))
-	} else {
-		baseProtoSum = uint32(checksum.Checksum(pkt[ipv6SrcOff:ipv6AddrsEnd], 0))
-	}
-	baseProtoSum += uint32(unix.IPPROTO_TCP)
-
-	var origIPID uint16
-	var baseIPHdrSum uint32
-	if isV4 {
-		origIPID = binary.BigEndian.Uint16(pkt[ipv4IDOff : ipv4IDOff+2])
-		ihl := int(pkt[0]&0x0f) * 4
-		if ihl < ipv4HeaderMinLen || ihl > csumStart {
-			return fmt.Errorf("bad IPv4 IHL: %d", ihl)
-		}
-		var ipTmp [ipv4HeaderMaxLen]byte
-		copy(ipTmp[:ihl], pkt[:ihl])
-		ipTmp[ipv4TotalLenOff], ipTmp[ipv4TotalLenOff+1] = 0, 0
-		ipTmp[ipv4IDOff], ipTmp[ipv4IDOff+1] = 0, 0
-		ipTmp[ipv4ChecksumOff], ipTmp[ipv4ChecksumOff+1] = 0, 0
-		baseIPHdrSum = uint32(checksum.Checksum(ipTmp[:ihl], 0))
-	}
-
-	for i := 0; i < numSeg; i++ {
-		segStart := i * gsoSize
-		segEnd := segStart + gsoSize
-		if segEnd > payLen {
-			segEnd = payLen
-		}
-		segPayLen := segEnd - segStart
-		segLen := headerLen + segPayLen
-		headerOff := i * gsoSize
-
-		// Slide the header into place immediately before this segment's
-		// payload. Iter 0's header is already at pkt[:headerLen]; for
-		// i ≥ 1 we copy from there. The constant-byte fields of pkt[:headerLen]
-		// survive iter 0's in-place patches (only seq/flags/cksum/totalLen/id
-		// are touched), and iter 0's stale variable-field values are
-		// overwritten by the per-segment patches below.
-		if i > 0 {
-			copy(pkt[headerOff:headerOff+headerLen], pkt[:headerLen])
-		}
-		seg := pkt[headerOff : headerOff+segLen]
-
-		segSeq := origSeq + uint32(segStart)
-		segFlags := origFlags
-		if i != 0 {
-			segFlags &^= tcpCwrFlag
-		}
-		if i != numSeg-1 {
-			segFlags &^= tcpFinPshMask
-		}
-		totalLen := segLen
-
-		if isV4 {
-			segID := origIPID + uint16(i)
-			binary.BigEndian.PutUint16(seg[ipv4TotalLenOff:ipv4TotalLenOff+2], uint16(totalLen))
-			binary.BigEndian.PutUint16(seg[ipv4IDOff:ipv4IDOff+2], segID)
-			ipSum := baseIPHdrSum + uint32(totalLen) + uint32(segID)
-			binary.BigEndian.PutUint16(seg[ipv4ChecksumOff:ipv4ChecksumOff+2], foldComplement(ipSum))
-		} else {
-			binary.BigEndian.PutUint16(seg[ipv6PayloadLenOff:ipv6PayloadLenOff+2], uint16(headerLen-ipv6FixedLen+segPayLen))
-		}
-
-		binary.BigEndian.PutUint32(seg[csumStart+tcpSeqOff:csumStart+tcpSeqOff+4], segSeq)
-		seg[csumStart+tcpFlagsOff] = segFlags
-
-		tcpLen := tcpHdrLen + segPayLen
-		// Payload bytes still live at their original offset in pkt. The
-		// header slide above only writes into pkt[i*G : i*G+H], which is
-		// the tail of seg_{i-1}'s payload (already consumed) and never
-		// overlaps seg_i's own payload at pkt[H+i*G : H+(i+1)*G].
-		paySum := uint32(checksum.Checksum(pkt[headerLen+segStart:headerLen+segEnd], 0))
-		wide := uint64(baseTcpHdrSum) + uint64(paySum) + uint64(baseProtoSum)
-		wide += uint64(segSeq) + uint64(segFlags) + uint64(tcpLen)
-		wide = (wide & 0xffffffff) + (wide >> 32)
-		wide = (wide & 0xffffffff) + (wide >> 32)
-		binary.BigEndian.PutUint16(seg[csumStart+tcpChecksumOff:csumStart+tcpChecksumOff+2], foldComplement(uint32(wide)))
-
-		if err := yield(seg); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-// SegmentUDP walks a USO superpacket, sliding a per-segment-patched
-// L3+L4 header into pkt at offset i*gsoSize and yielding pkt[i*G:i*G+segLen]
-// to the caller. Per-segment patches are total_len + IPv4 csum (or IPv6
-// payload_len) plus the UDP length and checksum. pkt is consumed
-// destructively; see SegmentTCP for the layout reasoning.
-//
-// UDP-GSO leaves the IPv4 ID identical across segments (the kernel does not
-// bump it), which is why the IP-level per-segment work is limited to
-// total_len + IPv4 header checksum (v4) or payload_len (v6).
-func SegmentUDP(pkt []byte, hdrLenU, csumStartU, gsoSizeU uint16, yield func(seg []byte) error) error {
-	if gsoSizeU == 0 {
-		return fmt.Errorf("gso_size is zero")
-	}
-	if csumStartU == 0 {
-		return fmt.Errorf("csum_start is zero")
-	}
-
-	isV4 := pkt[0]>>4 == 4
-	headerLen := int(hdrLenU)
-	csumStart := int(csumStartU)
-	if headerLen-csumStart != udpHeaderLen {
-		return fmt.Errorf("udp header len mismatch: %d", headerLen-csumStart)
-	}
-
-	payLen := len(pkt) - headerLen
-	gsoSize := int(gsoSizeU)
-	numSeg := (payLen + gsoSize - 1) / gsoSize
-	if numSeg == 0 {
-		numSeg = 1
-	}
-
-	var udpTmp [udpHeaderLen]byte
-	copy(udpTmp[:], pkt[csumStart:headerLen])
-	udpTmp[udpLengthOff], udpTmp[udpLengthOff+1] = 0, 0
-	udpTmp[udpChecksumOff], udpTmp[udpChecksumOff+1] = 0, 0
-	baseUDPHdrSum := uint32(checksum.Checksum(udpTmp[:], 0))
-
-	var baseProtoSum uint32
-	if isV4 {
-		baseProtoSum = uint32(checksum.Checksum(pkt[ipv4SrcOff:ipv4AddrsEnd], 0))
-	} else {
-		baseProtoSum = uint32(checksum.Checksum(pkt[ipv6SrcOff:ipv6AddrsEnd], 0))
-	}
-	baseProtoSum += uint32(unix.IPPROTO_UDP)
-
-	var baseIPHdrSum uint32
-	if isV4 {
-		ihl := int(pkt[0]&0x0f) * 4
-		if ihl < ipv4HeaderMinLen || ihl > csumStart {
-			return fmt.Errorf("bad IPv4 IHL: %d", ihl)
-		}
-		var ipTmp [ipv4HeaderMaxLen]byte
-		copy(ipTmp[:ihl], pkt[:ihl])
-		ipTmp[ipv4TotalLenOff], ipTmp[ipv4TotalLenOff+1] = 0, 0
-		ipTmp[ipv4ChecksumOff], ipTmp[ipv4ChecksumOff+1] = 0, 0
-		baseIPHdrSum = uint32(checksum.Checksum(ipTmp[:ihl], 0))
-	}
-
-	for i := 0; i < numSeg; i++ {
-		segStart := i * gsoSize
-		segEnd := segStart + gsoSize
-		if segEnd > payLen {
-			segEnd = payLen
-		}
-		segPayLen := segEnd - segStart
-		segLen := headerLen + segPayLen
-		headerOff := i * gsoSize
-
-		if i > 0 {
-			copy(pkt[headerOff:headerOff+headerLen], pkt[:headerLen])
-		}
-		seg := pkt[headerOff : headerOff+segLen]
-
-		totalLen := segLen
-		udpLen := udpHeaderLen + segPayLen
-
-		if isV4 {
-			binary.BigEndian.PutUint16(seg[ipv4TotalLenOff:ipv4TotalLenOff+2], uint16(totalLen))
-			ipSum := baseIPHdrSum + uint32(totalLen)
-			binary.BigEndian.PutUint16(seg[ipv4ChecksumOff:ipv4ChecksumOff+2], foldComplement(ipSum))
-		} else {
-			binary.BigEndian.PutUint16(seg[ipv6PayloadLenOff:ipv6PayloadLenOff+2], uint16(headerLen-ipv6FixedLen+segPayLen))
-		}
-
-		binary.BigEndian.PutUint16(seg[csumStart+udpLengthOff:csumStart+udpLengthOff+2], uint16(udpLen))
-
-		paySum := uint32(checksum.Checksum(pkt[headerLen+segStart:headerLen+segEnd], 0))
-		wide := uint64(baseUDPHdrSum) + uint64(paySum) + uint64(baseProtoSum)
-		wide += uint64(udpLen) + uint64(udpLen)
-		wide = (wide & 0xffffffff) + (wide >> 32)
-		wide = (wide & 0xffffffff) + (wide >> 32)
-		csum := foldComplement(uint32(wide))
-		if csum == 0 {
-			csum = 0xffff
-		}
-		binary.BigEndian.PutUint16(seg[csumStart+udpChecksumOff:csumStart+udpChecksumOff+2], csum)
-
-		if err := yield(seg); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-// FinishChecksum computes the L4 checksum for a non-GSO packet that the kernel
-// handed us with NEEDS_CSUM set. csum_start / csum_offset point at the 16-bit
-// checksum field; we zero it, fold a full sum (the field was pre-loaded with
-// the pseudo-header partial sum by the kernel), and store the result.
-func FinishChecksum(seg []byte, hdr Hdr) error {
-	cs := int(hdr.CsumStart)
-	co := int(hdr.CsumOffset)
-	if cs+co+2 > len(seg) {
-		return fmt.Errorf("csum offsets out of range: start=%d offset=%d len=%d", cs, co, len(seg))
-	}
-	// The kernel stores a partial pseudo-header sum at [cs+co:]; sum over the
-	// L4 region starting at cs, folding the prior partial in as the seed.
-	partial := binary.BigEndian.Uint16(seg[cs+co : cs+co+2])
-	seg[cs+co] = 0
-	seg[cs+co+1] = 0
-	binary.BigEndian.PutUint16(seg[cs+co:cs+co+2], ^checksum.Checksum(seg[cs:], partial))
-	return nil
-}
-
-// foldComplement folds a 32-bit one's-complement partial sum to 16 bits and
-// complements it, yielding the on-wire Internet checksum value.
-func foldComplement(sum uint32) uint16 {
-	sum = (sum & 0xffff) + (sum >> 16)
-	sum = (sum & 0xffff) + (sum >> 16)
-	return ^uint16(sum)
-}

overlay/tun_android.go

@@ -13,38 +13,17 @@ import (
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 )
 
 type tun struct {
-	rwc         io.ReadWriteCloser
+	io.ReadWriteCloser
 	fd          int
 	vpnNetworks []netip.Prefix
 	Routes      atomic.Pointer[[]Route]
 	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
 	l           *slog.Logger
-
-	readBuf  []byte
-	batchRet [1]tio.Packet
-}
-
-func (t *tun) Read() ([]tio.Packet, error) {
-	n, err := t.rwc.Read(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = tio.Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
-}
-
-func (t *tun) Write(p []byte) (int, error) {
-	return t.rwc.Write(p)
-}
-
-func (t *tun) Close() error {
-	return t.rwc.Close()
 }
 
 func newTunFromFd(c *config.C, l *slog.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
@@ -53,11 +32,10 @@ func newTunFromFd(c *config.C, l *slog.Logger, deviceFd int, vpnNetworks []netip
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
 	t := &tun{
-		rwc:         file,
-		fd:          deviceFd,
-		vpnNetworks: vpnNetworks,
-		l:           l,
-		readBuf:     make([]byte, defaultBatchBufSize),
+		ReadWriteCloser: file,
+		fd:              deviceFd,
+		vpnNetworks:     vpnNetworks,
+		l:               l,
 	}
 
 	err := t.reload(c, true)
@@ -84,7 +62,7 @@ func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
 	return r
 }
 
-func (t *tun) Activate() error {
+func (t tun) Activate() error {
 	return nil
 }
 
@@ -121,10 +99,8 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented for android")
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for android")
 }
 
-func (t *tun) Readers() []tio.Queue {
-	return []tio.Queue{t}
-}
+func (t *tun) TunPrefixLen() int { return 0 }

overlay/tun_bsd.go

@@ -0,0 +1,29 @@
+//go:build (darwin || ios || freebsd || openbsd || netbsd) && !e2e_testing
+
+package overlay
+
+import (
+	"fmt"
+	"syscall"
+)
+
+// StampTunPrefix writes the 4-byte AF_INET / AF_INET6 protocol-family marker into buf[0:4] in place,
+// picking the family from the first byte of the IP packet at buf[4].
+func StampTunPrefix(buf []byte) error {
+	if len(buf) < 5 {
+		return fmt.Errorf("tun write buffer too small for prefix")
+	}
+	ipVer := buf[4] >> 4
+	buf[0] = 0
+	buf[1] = 0
+	buf[2] = 0
+	switch ipVer {
+	case 4:
+		buf[3] = syscall.AF_INET
+	case 6:
+		buf[3] = syscall.AF_INET6
+	default:
+		return fmt.Errorf("unable to determine IP version from packet")
+	}
+	return nil
+}

overlay/tun_bypass_windows.go

@@ -1,23 +0,0 @@
-//go:build (amd64 || arm64) && !e2e_testing
-// +build amd64 arm64
-// +build !e2e_testing
-
-package overlay
-
-import (
-	"log/slog"
-
-	"github.com/slackhq/nebula/wfp"
-)
-
-// installInterfaceBypass installs a WFP PERMIT filter scoped to the wintun interface LUID so inbound traffic on the
-// nebula adapter bypasses Windows Defender Firewall.
-func installInterfaceBypass(l *slog.Logger, luid uint64) closer {
-	s, err := wfp.PermitInterface(luid)
-	if err != nil {
-		l.Warn("Failed to install WFP bypass filters on nebula interface", "error", err)
-		return nil
-	}
-	l.Info("Installed WFP filters bypassing Windows Defender Firewall on nebula interface")
-	return s
-}

overlay/tun_bypass_windows_386.go

@@ -1,11 +0,0 @@
-//go:build !e2e_testing
-// +build !e2e_testing
-
-package overlay
-
-import "log/slog"
-
-// installInterfaceBypass is a no-op on windows-386 because we don't currently build for it.
-func installInterfaceBypass(_ *slog.Logger, _ uint64) closer {
-	return nil
-}

overlay/tun_darwin.go

@@ -11,12 +11,10 @@ import (
 	"net/netip"
 	"os"
 	"sync/atomic"
-	"syscall"
 	"unsafe"
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 	netroute "golang.org/x/net/route"
@@ -24,7 +22,7 @@ import (
 )
 
 type tun struct {
-	rwc         io.ReadWriteCloser
+	io.ReadWriteCloser
 	Device      string
 	vpnNetworks []netip.Prefix
 	DefaultMTU  int
@@ -32,12 +30,6 @@ type tun struct {
 	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
 	linkAddr    *netroute.LinkAddr
 	l           *slog.Logger
-
-	// cache out buffer since we need to prepend 4 bytes for tun metadata
-	out []byte
-
-	readBuf  []byte
-	batchRet [1]tio.Packet
 }
 
 type ifReq struct {
@@ -128,12 +120,11 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*t
 	}
 
 	t := &tun{
-		rwc:         os.NewFile(uintptr(fd), ""),
-		Device:      name,
-		vpnNetworks: vpnNetworks,
-		DefaultMTU:  c.GetInt("tun.mtu", DefaultMTU),
-		l:           l,
-		readBuf:     make([]byte, defaultBatchBufSize),
+		ReadWriteCloser: os.NewFile(uintptr(fd), ""),
+		Device:          name,
+		vpnNetworks:     vpnNetworks,
+		DefaultMTU:      c.GetInt("tun.mtu", DefaultMTU),
+		l:               l,
 	}
 
 	err = t.reload(c, true)
@@ -163,8 +154,8 @@ func newTunFromFd(_ *config.C, _ *slog.Logger, _ int, _ []netip.Prefix) (*tun, e
 }
 
 func (t *tun) Close() error {
-	if t.rwc != nil {
-		return t.rwc.Close()
+	if t.ReadWriteCloser != nil {
+		return t.ReadWriteCloser.Close()
 	}
 	return nil
 }
@@ -507,53 +498,6 @@ func delRoute(prefix netip.Prefix, gateway netroute.Addr) error {
 	return nil
 }
 
-func (t *tun) readOne(to []byte) (int, error) {
-	buf := make([]byte, len(to)+4)
-
-	n, err := t.rwc.Read(buf)
-
-	copy(to, buf[4:])
-	return n - 4, err
-}
-
-func (t *tun) Read() ([]tio.Packet, error) {
-	n, err := t.readOne(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = tio.Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
-}
-
-// Write is only valid for single threaded use
-func (t *tun) Write(from []byte) (int, error) {
-	buf := t.out
-	if cap(buf) < len(from)+4 {
-		buf = make([]byte, len(from)+4)
-		t.out = buf
-	}
-	buf = buf[:len(from)+4]
-
-	if len(from) == 0 {
-		return 0, syscall.EIO
-	}
-
-	// Determine the IP Family for the NULL L2 Header
-	ipVer := from[0] >> 4
-	if ipVer == 4 {
-		buf[3] = syscall.AF_INET
-	} else if ipVer == 6 {
-		buf[3] = syscall.AF_INET6
-	} else {
-		return 0, fmt.Errorf("unable to determine IP version from packet")
-	}
-
-	copy(buf[4:], from)
-
-	n, err := t.rwc.Write(buf)
-	return n - 4, err
-}
-
 func (t *tun) Networks() []netip.Prefix {
 	return t.vpnNetworks
 }
@@ -566,10 +510,10 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented for darwin")
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for darwin")
 }
 
-func (t *tun) Readers() []tio.Queue {
-	return []tio.Queue{t}
-}
+// TunPrefixLen reports the 4-byte BSD AF_INET / AF_INET6 protocol-family
+// marker the kernel prepends on read and expects on write.
+func (t *tun) TunPrefixLen() int { return 4 }

overlay/tun_disabled.go

@@ -10,7 +10,6 @@ import (
 
 	"github.com/rcrowley/go-metrics"
 	"github.com/slackhq/nebula/iputil"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 )
 
@@ -19,45 +18,9 @@ type disabledTun struct {
 	vpnNetworks []netip.Prefix
 
 	// Track these metrics since we don't have the tun device to do it for us
-	tx         metrics.Counter
-	rx         metrics.Counter
-	l          *slog.Logger
-	numReaders int
-}
-
-// disabledQueue is one tio.Queue view onto a shared disabledTun. Each queue
-// owns a private batchRet so concurrent Read calls from different reader
-// goroutines do not race on the returned slice.
-type disabledQueue struct {
-	parent   *disabledTun
-	batchRet [1]tio.Packet
-}
-
-func (q *disabledQueue) Read() ([]tio.Packet, error) {
-	r, ok := <-q.parent.read
-	if !ok {
-		return nil, io.EOF
-	}
-
-	q.parent.tx.Inc(1)
-	if q.parent.l.Enabled(context.Background(), slog.LevelDebug) {
-		q.parent.l.Debug("Write payload", "raw", prettyPacket(r))
-	}
-
-	q.batchRet[0] = tio.Packet{Bytes: r}
-	return q.batchRet[:], nil
-}
-
-// Write on a queue forwards to the underlying disabledTun. All queues share
-// one ICMP-handling/log path so this is a thin pass-through.
-func (q *disabledQueue) Write(b []byte) (int, error) {
-	return q.parent.Write(b)
-}
-
-// Close on a queue is a no-op. The shared channel and metrics are owned by
-// the disabledTun; Close on the device tears them down once for everybody.
-func (q *disabledQueue) Close() error {
-	return nil
+	tx metrics.Counter
+	rx metrics.Counter
+	l  *slog.Logger
 }
 
 func newDisabledTun(vpnNetworks []netip.Prefix, queueLen int, metricsEnabled bool, l *slog.Logger) *disabledTun {
@@ -65,7 +28,6 @@ func newDisabledTun(vpnNetworks []netip.Prefix, queueLen int, metricsEnabled boo
 		vpnNetworks: vpnNetworks,
 		read:        make(chan []byte, queueLen),
 		l:           l,
-		numReaders:  1,
 	}
 
 	if metricsEnabled {
@@ -95,6 +57,24 @@ func (*disabledTun) Name() string {
 	return "disabled"
 }
 
+func (t *disabledTun) Read(b []byte) (int, error) {
+	r, ok := <-t.read
+	if !ok {
+		return 0, io.EOF
+	}
+
+	if len(r) > len(b) {
+		return 0, fmt.Errorf("packet larger than mtu: %d > %d bytes", len(r), len(b))
+	}
+
+	t.tx.Inc(1)
+	if t.l.Enabled(context.Background(), slog.LevelDebug) {
+		t.l.Debug("Write payload", "raw", prettyPacket(r))
+	}
+
+	return copy(b, r), nil
+}
+
 func (t *disabledTun) handleICMPEchoRequest(b []byte) bool {
 	out := make([]byte, len(b))
 	out = iputil.CreateICMPEchoResponse(b, out)
@@ -130,17 +110,8 @@ func (t *disabledTun) SupportsMultiqueue() bool {
 	return true
 }
 
-func (t *disabledTun) NewMultiQueueReader() error {
-	t.numReaders++
-	return nil
-}
-
-func (t *disabledTun) Readers() []tio.Queue {
-	out := make([]tio.Queue, t.numReaders)
-	for i := range t.numReaders {
-		out[i] = &disabledQueue{parent: t}
-	}
-	return out
+func (t *disabledTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return t, nil
 }
 
 func (t *disabledTun) Close() error {
@@ -165,3 +136,5 @@ func (p prettyPacket) String() string {
 
 	return s.String()
 }
+
+func (t *disabledTun) TunPrefixLen() int { return 0 }

overlay/tun_file_linux_test.go

@@ -0,0 +1,120 @@
+//go:build linux && !android && !e2e_testing
+// +build linux,!android,!e2e_testing
+
+package overlay
+
+import (
+	"errors"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+// newReadPipe returns a read fd. The matching write fd is registered for cleanup.
+// The caller takes ownership of the read fd (pass it to newTunFd / newFriend).
+func newReadPipe(t *testing.T) int {
+	t.Helper()
+	var fds [2]int
+	if err := unix.Pipe2(fds[:], unix.O_CLOEXEC); err != nil {
+		t.Fatalf("pipe2: %v", err)
+	}
+	t.Cleanup(func() { _ = unix.Close(fds[1]) })
+	return fds[0]
+}
+
+func TestTunFile_WakeForShutdown_UnblocksRead(t *testing.T) {
+	tf, err := newTunFd(newReadPipe(t))
+	if err != nil {
+		t.Fatalf("newTunFd: %v", err)
+	}
+	t.Cleanup(func() { _ = tf.Close() })
+
+	done := make(chan error, 1)
+	go func() {
+		_, err := tf.Read(make([]byte, 64))
+		done <- err
+	}()
+
+	// Verify Read is actually blocked in poll.
+	select {
+	case err := <-done:
+		t.Fatalf("Read returned before shutdown signal: %v", err)
+	case <-time.After(50 * time.Millisecond):
+	}
+
+	if err := tf.wakeForShutdown(); err != nil {
+		t.Fatalf("wakeForShutdown: %v", err)
+	}
+
+	select {
+	case err := <-done:
+		if !errors.Is(err, os.ErrClosed) {
+			t.Fatalf("expected os.ErrClosed, got %v", err)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("Read did not wake on shutdown")
+	}
+}
+
+func TestTunFile_WakeForShutdown_WakesFriends(t *testing.T) {
+	parent, err := newTunFd(newReadPipe(t))
+	if err != nil {
+		t.Fatalf("newTunFd: %v", err)
+	}
+	friend, err := parent.newFriend(newReadPipe(t))
+	if err != nil {
+		_ = parent.Close()
+		t.Fatalf("newFriend: %v", err)
+	}
+	t.Cleanup(func() {
+		_ = friend.Close()
+		_ = parent.Close()
+	})
+
+	readers := []*tunFile{parent, friend}
+	errs := make([]error, len(readers))
+	var wg sync.WaitGroup
+	for i, r := range readers {
+		wg.Add(1)
+		go func(i int, r *tunFile) {
+			defer wg.Done()
+			_, errs[i] = r.Read(make([]byte, 64))
+		}(i, r)
+	}
+
+	time.Sleep(50 * time.Millisecond)
+
+	if err := parent.wakeForShutdown(); err != nil {
+		t.Fatalf("wakeForShutdown: %v", err)
+	}
+
+	done := make(chan struct{})
+	go func() { wg.Wait(); close(done) }()
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Fatal("readers did not wake")
+	}
+
+	for i, err := range errs {
+		if !errors.Is(err, os.ErrClosed) {
+			t.Errorf("reader %d: expected os.ErrClosed, got %v", i, err)
+		}
+	}
+}
+
+func TestTunFile_Close_Idempotent(t *testing.T) {
+	tf, err := newTunFd(newReadPipe(t))
+	if err != nil {
+		t.Fatalf("newTunFd: %v", err)
+	}
+	if err := tf.Close(); err != nil {
+		t.Fatalf("first Close: %v", err)
+	}
+	if err := tf.Close(); err != nil {
+		t.Fatalf("second Close should be a no-op, got %v", err)
+	}
+}

overlay/tun_freebsd.go

@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"io"
 	"io/fs"
 	"log/slog"
 	"net/netip"
@@ -19,7 +20,7 @@ import (
 	"github.com/gaissmai/bart"
 
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
+
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 	netroute "golang.org/x/net/route"
@@ -102,9 +103,6 @@ type tun struct {
 	readPoll  [2]unix.PollFd
 	writePoll [2]unix.PollFd
 	closed    atomic.Bool
-
-	readBuf  []byte
-	batchRet [1]tio.Packet
 }
 
 // blockOnRead waits until the tun fd is readable or shutdown has been signaled.
@@ -159,84 +157,44 @@ func (t *tun) blockOnWrite() error {
 	return nil
 }
 
-func (t *tun) Read() ([]tio.Packet, error) {
-	n, err := t.readOne(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = tio.Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
-}
-
-func (t *tun) readOne(to []byte) (int, error) {
-	// first 4 bytes is protocol family, in network byte order
-	var head [4]byte
-	iovecs := [2]syscall.Iovec{
-		{&head[0], 4},
-		{&to[0], uint64(len(to))},
-	}
+func (t *tun) Read(to []byte) (int, error) {
 	for {
-		n, _, errno := syscall.Syscall(syscall.SYS_READV, uintptr(t.fd), uintptr(unsafe.Pointer(&iovecs[0])), 2)
-		if errno == 0 {
-			bytesRead := int(n)
-			if bytesRead < 4 {
-				return 0, nil
-			}
-			return bytesRead - 4, nil
+		n, err := unix.Read(t.fd, to)
+		if err == nil {
+			return n, nil
 		}
-		switch errno {
+		switch err {
 		case unix.EAGAIN:
-			if err := t.blockOnRead(); err != nil {
-				return 0, err
+			if berr := t.blockOnRead(); berr != nil {
+				return 0, berr
 			}
 		case unix.EINTR:
 			// retry
 		case unix.EBADF:
 			return 0, os.ErrClosed
 		default:
-			return 0, errno
+			return 0, err
 		}
 	}
 }
 
-// Write is only valid for single threaded use
 func (t *tun) Write(from []byte) (int, error) {
-	if len(from) <= 1 {
-		return 0, syscall.EIO
-	}
-
-	ipVer := from[0] >> 4
-	var head [4]byte
-	// first 4 bytes is protocol family, in network byte order
-	switch ipVer {
-	case 4:
-		head[3] = syscall.AF_INET
-	case 6:
-		head[3] = syscall.AF_INET6
-	default:
-		return 0, fmt.Errorf("unable to determine IP version from packet")
-	}
-
-	iovecs := [2]syscall.Iovec{
-		{&head[0], 4},
-		{&from[0], uint64(len(from))},
-	}
 	for {
-		n, _, errno := syscall.Syscall(syscall.SYS_WRITEV, uintptr(t.fd), uintptr(unsafe.Pointer(&iovecs[0])), 2)
-		if errno == 0 {
-			return int(n) - 4, nil
+		n, err := unix.Write(t.fd, from)
+		if err == nil {
+			return n, nil
 		}
-		switch errno {
+		switch err {
 		case unix.EAGAIN:
-			if err := t.blockOnWrite(); err != nil {
-				return 0, err
+			if berr := t.blockOnWrite(); berr != nil {
+				return 0, berr
 			}
 		case unix.EINTR:
 			// retry
 		case unix.EBADF:
 			return 0, os.ErrClosed
 		default:
-			return 0, errno
+			return 0, err
 		}
 	}
 }
@@ -386,7 +344,6 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*t
 		MTU:         c.GetInt("tun.mtu", DefaultMTU),
 		l:           l,
 		fd:          fd,
-		readBuf:     make([]byte, defaultBatchBufSize),
 		shutdownR:   shutdownR,
 		shutdownW:   shutdownW,
 		readPoll: [2]unix.PollFd{
@@ -577,8 +534,8 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented for freebsd")
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for freebsd")
 }
 
 func (t *tun) addRoutes(logErrors bool) error {
@@ -605,10 +562,6 @@ func (t *tun) addRoutes(logErrors bool) error {
 	return nil
 }
 
-func (t *tun) Readers() []tio.Queue {
-	return []tio.Queue{t}
-}
-
 func (t *tun) removeRoutes(routes []Route) error {
 	for _, r := range routes {
 		if !r.Install {
@@ -748,3 +701,7 @@ func getLinkAddr(name string) (*netroute.LinkAddr, error) {
 
 	return nil, nil
 }
+
+// TunPrefixLen reports the 4-byte BSD AF_INET / AF_INET6 protocol-family
+// marker the kernel prepends on read and expects on write.
+func (t *tun) TunPrefixLen() int { return 4 }

overlay/tun_ios.go

@@ -4,49 +4,25 @@
 package overlay
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"log/slog"
 	"net/netip"
 	"os"
-	"sync"
 	"sync/atomic"
-	"syscall"
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 )
 
 type tun struct {
-	rwc         io.ReadWriteCloser
+	io.ReadWriteCloser
 	vpnNetworks []netip.Prefix
 	Routes      atomic.Pointer[[]Route]
 	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
 	l           *slog.Logger
-
-	readBuf  []byte
-	batchRet [1]tio.Packet
-}
-
-func (t *tun) Read() ([]tio.Packet, error) {
-	n, err := t.rwc.Read(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = tio.Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
-}
-
-func (t *tun) Write(p []byte) (int, error) {
-	return t.rwc.Write(p)
-}
-
-func (t *tun) Close() error {
-	return t.rwc.Close()
 }
 
 func newTun(_ *config.C, _ *slog.Logger, _ []netip.Prefix, _ bool) (*tun, error) {
@@ -56,10 +32,9 @@ func newTun(_ *config.C, _ *slog.Logger, _ []netip.Prefix, _ bool) (*tun, error)
 func newTunFromFd(c *config.C, l *slog.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
 	file := os.NewFile(uintptr(deviceFd), "/dev/tun")
 	t := &tun{
-		vpnNetworks: vpnNetworks,
-		rwc:         &tunReadCloser{f: file},
-		l:           l,
-		readBuf:     make([]byte, defaultBatchBufSize),
+		vpnNetworks:     vpnNetworks,
+		ReadWriteCloser: file,
+		l:               l,
 	}
 
 	err := t.reload(c, true)
@@ -107,64 +82,6 @@ func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
 	return r
 }
 
-// The following is hoisted up from water, we do this so we can inject our own fd on iOS
-type tunReadCloser struct {
-	f io.ReadWriteCloser
-
-	rMu  sync.Mutex
-	rBuf []byte
-
-	wMu  sync.Mutex
-	wBuf []byte
-}
-
-func (tr *tunReadCloser) Read(to []byte) (int, error) {
-	tr.rMu.Lock()
-	defer tr.rMu.Unlock()
-
-	if cap(tr.rBuf) < len(to)+4 {
-		tr.rBuf = make([]byte, len(to)+4)
-	}
-	tr.rBuf = tr.rBuf[:len(to)+4]
-
-	n, err := tr.f.Read(tr.rBuf)
-	copy(to, tr.rBuf[4:])
-	return n - 4, err
-}
-
-func (tr *tunReadCloser) Write(from []byte) (int, error) {
-	if len(from) == 0 {
-		return 0, syscall.EIO
-	}
-
-	tr.wMu.Lock()
-	defer tr.wMu.Unlock()
-
-	if cap(tr.wBuf) < len(from)+4 {
-		tr.wBuf = make([]byte, len(from)+4)
-	}
-	tr.wBuf = tr.wBuf[:len(from)+4]
-
-	// Determine the IP Family for the NULL L2 Header
-	ipVer := from[0] >> 4
-	if ipVer == 4 {
-		tr.wBuf[3] = syscall.AF_INET
-	} else if ipVer == 6 {
-		tr.wBuf[3] = syscall.AF_INET6
-	} else {
-		return 0, errors.New("unable to determine IP version from packet")
-	}
-
-	copy(tr.wBuf[4:], from)
-
-	n, err := tr.f.Write(tr.wBuf)
-	return n - 4, err
-}
-
-func (tr *tunReadCloser) Close() error {
-	return tr.f.Close()
-}
-
 func (t *tun) Networks() []netip.Prefix {
 	return t.vpnNetworks
 }
@@ -177,10 +94,10 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented for ios")
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for ios")
 }
 
-func (t *tun) Readers() []tio.Queue {
-	return []tio.Queue{t}
-}
+// TunPrefixLen reports the 4-byte BSD AF_INET / AF_INET6 protocol-family
+// marker the kernel prepends on read and expects on write.
+func (t *tun) TunPrefixLen() int { return 4 }

overlay/tun_linux.go

@@ -4,7 +4,9 @@
 package overlay
 
 import (
+	"encoding/binary"
 	"fmt"
+	"io"
 	"log/slog"
 	"net"
 	"net/netip"
@@ -17,15 +19,180 @@ import (
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 	"github.com/vishvananda/netlink"
 	"golang.org/x/sys/unix"
 )
 
+// tunFile wraps a TUN file descriptor with poll-based reads. The FD provided will be changed to non-blocking.
+// A shared eventfd allows Close to wake all readers blocked in poll.
+type tunFile struct {
+	fd         int
+	shutdownFd int
+	lastOne    bool
+	readPoll   [2]unix.PollFd
+	writePoll  [2]unix.PollFd
+	closed     bool
+}
+
+// newFriend makes a tunFile for a MultiQueueReader that copies the shutdown eventfd from the parent tun
+func (r *tunFile) newFriend(fd int) (*tunFile, error) {
+	if err := unix.SetNonblock(fd, true); err != nil {
+		return nil, fmt.Errorf("failed to set tun fd non-blocking: %w", err)
+	}
+	return &tunFile{
+		fd:         fd,
+		shutdownFd: r.shutdownFd,
+		readPoll: [2]unix.PollFd{
+			{Fd: int32(fd), Events: unix.POLLIN},
+			{Fd: int32(r.shutdownFd), Events: unix.POLLIN},
+		},
+		writePoll: [2]unix.PollFd{
+			{Fd: int32(fd), Events: unix.POLLOUT},
+			{Fd: int32(r.shutdownFd), Events: unix.POLLIN},
+		},
+	}, nil
+}
+
+func newTunFd(fd int) (*tunFile, error) {
+	if err := unix.SetNonblock(fd, true); err != nil {
+		return nil, fmt.Errorf("failed to set tun fd non-blocking: %w", err)
+	}
+
+	shutdownFd, err := unix.Eventfd(0, unix.EFD_NONBLOCK|unix.EFD_CLOEXEC)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create eventfd: %w", err)
+	}
+
+	out := &tunFile{
+		fd:         fd,
+		shutdownFd: shutdownFd,
+		lastOne:    true,
+		readPoll: [2]unix.PollFd{
+			{Fd: int32(fd), Events: unix.POLLIN},
+			{Fd: int32(shutdownFd), Events: unix.POLLIN},
+		},
+		writePoll: [2]unix.PollFd{
+			{Fd: int32(fd), Events: unix.POLLOUT},
+			{Fd: int32(shutdownFd), Events: unix.POLLIN},
+		},
+	}
+
+	return out, nil
+}
+
+func (r *tunFile) blockOnRead() error {
+	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
+	var err error
+	for {
+		_, err = unix.Poll(r.readPoll[:], -1)
+		if err != unix.EINTR {
+			break
+		}
+	}
+	//always reset these!
+	tunEvents := r.readPoll[0].Revents
+	shutdownEvents := r.readPoll[1].Revents
+	r.readPoll[0].Revents = 0
+	r.readPoll[1].Revents = 0
+	//do the err check before trusting the potentially bogus bits we just got
+	if err != nil {
+		return err
+	}
+	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
+		return os.ErrClosed
+	} else if tunEvents&problemFlags != 0 {
+		return os.ErrClosed
+	}
+	return nil
+}
+
+func (r *tunFile) blockOnWrite() error {
+	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
+	var err error
+	for {
+		_, err = unix.Poll(r.writePoll[:], -1)
+		if err != unix.EINTR {
+			break
+		}
+	}
+	//always reset these!
+	tunEvents := r.writePoll[0].Revents
+	shutdownEvents := r.writePoll[1].Revents
+	r.writePoll[0].Revents = 0
+	r.writePoll[1].Revents = 0
+	//do the err check before trusting the potentially bogus bits we just got
+	if err != nil {
+		return err
+	}
+	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
+		return os.ErrClosed
+	} else if tunEvents&problemFlags != 0 {
+		return os.ErrClosed
+	}
+	return nil
+}
+
+func (r *tunFile) Read(buf []byte) (int, error) {
+	for {
+		if n, err := unix.Read(r.fd, buf); err == nil {
+			return n, nil
+		} else if err == unix.EAGAIN {
+			if err = r.blockOnRead(); err != nil {
+				return 0, err
+			}
+			continue
+		} else if err == unix.EINTR {
+			continue
+		} else if err == unix.EBADF {
+			return 0, os.ErrClosed
+		} else {
+			return 0, err
+		}
+	}
+}
+
+func (r *tunFile) Write(buf []byte) (int, error) {
+	for {
+		if n, err := unix.Write(r.fd, buf); err == nil {
+			return n, nil
+		} else if err == unix.EAGAIN {
+			if err = r.blockOnWrite(); err != nil {
+				return 0, err
+			}
+			continue
+		} else if err == unix.EINTR {
+			continue
+		} else if err == unix.EBADF {
+			return 0, os.ErrClosed
+		} else {
+			return 0, err
+		}
+	}
+}
+
+func (r *tunFile) wakeForShutdown() error {
+	var buf [8]byte
+	binary.NativeEndian.PutUint64(buf[:], 1)
+	_, err := unix.Write(int(r.readPoll[1].Fd), buf[:])
+	return err
+}
+
+func (r *tunFile) Close() error {
+	if r.closed { // avoid closing more than once. Technically a fd could get re-used, which would be a problem
+		return nil
+	}
+	r.closed = true
+	if r.lastOne {
+		_ = unix.Close(r.shutdownFd)
+	}
+	return unix.Close(r.fd)
+}
+
 type tun struct {
-	readers     tio.QueueSet
+	*tunFile
+	readers     []*tunFile
 	closeLock   sync.Mutex
 	Device      string
 	vpnNetworks []netip.Prefix
@@ -34,14 +201,6 @@ type tun struct {
 	TXQueueLen  int
 	deviceIndex int
 	ioctlFd     uintptr
-	vnetHdr     bool
-	// routeFeatureECN, when true, sets RTAX_FEATURE_ECN on every route we
-	// install for the tun. The kernel then actively negotiates ECN for
-	// connections destined to those prefixes (equivalent to `ip route
-	// change ... features ecn`) regardless of net.ipv4.tcp_ecn, so flows
-	// across the nebula mesh use ECN even when the host default is the
-	// passive setting (=2). Disable via tunnels.ecn=false.
-	routeFeatureECN bool
 
 	Routes                    atomic.Pointer[[]Route]
 	routeTree                 atomic.Pointer[bart.Table[routing.Gateways]]
@@ -80,9 +239,7 @@ type ifreqQLEN struct {
 }
 
 func newTunFromFd(c *config.C, l *slog.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
-	// We don't know what flags the caller opened this fd with and can't turn
-	// on IFF_VNET_HDR after TUNSETIFF, so skip offload on inherited fds.
-	t, err := newTunGeneric(c, l, deviceFd, false, false, vpnNetworks)
+	t, err := newTunGeneric(c, l, deviceFd, vpnNetworks)
 	if err != nil {
 		return nil, err
 	}
@@ -92,105 +249,46 @@ func newTunFromFd(c *config.C, l *slog.Logger, deviceFd int, vpnNetworks []netip
 	return t, nil
 }
 
-// openTunDev opens /dev/net/tun, creating the device node first if it's
-// missing (docker containers occasionally omit it).
-func openTunDev() (int, error) {
-	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
-	if err == nil {
-		return fd, nil
-	}
-	if !os.IsNotExist(err) {
-		return -1, err
-	}
-	if err = os.MkdirAll("/dev/net", 0755); err != nil {
-		return -1, fmt.Errorf("/dev/net/tun doesn't exist, failed to mkdir -p /dev/net: %w", err)
-	}
-	if err = unix.Mknod("/dev/net/tun", unix.S_IFCHR|0600, int(unix.Mkdev(10, 200))); err != nil {
-		return -1, fmt.Errorf("failed to create /dev/net/tun: %w", err)
-	}
-	fd, err = unix.Open("/dev/net/tun", os.O_RDWR, 0)
-	if err != nil {
-		return -1, fmt.Errorf("created /dev/net/tun, but still failed: %w", err)
-	}
-	return fd, nil
-}
-
-// tunSetIff runs TUNSETIFF with the given flags and returns the kernel-chosen
-// device name on success.
-func tunSetIff(fd int, name string, flags uint16) (string, error) {
-	var req ifReq
-	req.Flags = flags
-	copy(req.Name[:], name)
-	if err := ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
-		return "", err
-	}
-	return strings.Trim(string(req.Name[:]), "\x00"), nil
-}
-
-// tsoOffloadFlags are the TUN_F_* bits we ask the kernel to enable when a
-// TSO-capable TUN is available. CSUM is required as a prerequisite for TSO.
-// TSO_ECN tells the kernel we propagate ECN correctly through coalesce and
-// segmentation, so it can deliver superpackets whose seed has CWR/ECE set
-// or whose IP-level codepoint is CE.
-const tsoOffloadFlags = unix.TUN_F_CSUM | unix.TUN_F_TSO4 | unix.TUN_F_TSO6 | unix.TUN_F_TSO_ECN
-
-// usoOffloadFlags adds UDP Segmentation Offload to tsoOffloadFlags. Requires
-// Linux ≥ 6.2; older kernels reject it and we fall back to TCP-only TSO via
-// tsoOffloadFlags.
-const usoOffloadFlags = tsoOffloadFlags | unix.TUN_F_USO4 | unix.TUN_F_USO6
-
 func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, multiqueue bool) (*tun, error) {
-	baseFlags := uint16(unix.IFF_TUN | unix.IFF_NO_PI)
-	if multiqueue {
-		baseFlags |= unix.IFF_MULTI_QUEUE
-	}
-	nameStr := c.GetString("tun.dev", "")
-
-	// First try to enable IFF_VNET_HDR via TUNSETIFF and negotiate TUN_F_*
-	// offloads via TUNSETOFFLOAD so we can receive TSO/USO superpackets.
-	// We try TSO+USO first, fall back to TSO-only on kernels without USO
-	// (Linux < 6.2), and finally give up on virtio headers entirely and
-	// reopen as a plain TUN if neither offload mask is accepted.
-	fd, err := openTunDev()
+	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
-		return nil, err
-	}
-	vnetHdr := true
-	usoEnabled := false
-	name, err := tunSetIff(fd, nameStr, baseFlags|unix.IFF_VNET_HDR)
-	if err != nil {
-		_ = unix.Close(fd)
-		vnetHdr = false
-	} else {
-		// Try TSO+USO first. On kernels without USO support (Linux < 6.2)
-		// the ioctl returns EINVAL; fall back to the TCP-only mask before
-		// giving up on VNET_HDR entirely.
-		if err = ioctl(uintptr(fd), unix.TUNSETOFFLOAD, uintptr(usoOffloadFlags)); err == nil {
-			usoEnabled = true
-		} else if err = ioctl(uintptr(fd), unix.TUNSETOFFLOAD, uintptr(tsoOffloadFlags)); err != nil {
-			l.Warn("Failed to enable TUN offload (TSO); proceeding without virtio headers", "error", err)
-			_ = unix.Close(fd)
-			vnetHdr = false
-		}
-	}
+		// If /dev/net/tun doesn't exist, try to create it (will happen in docker)
+		if os.IsNotExist(err) {
+			err = os.MkdirAll("/dev/net", 0755)
+			if err != nil {
+				return nil, fmt.Errorf("/dev/net/tun doesn't exist, failed to mkdir -p /dev/net: %w", err)
+			}
+			err = unix.Mknod("/dev/net/tun", unix.S_IFCHR|0600, int(unix.Mkdev(10, 200)))
+			if err != nil {
+				return nil, fmt.Errorf("failed to create /dev/net/tun: %w", err)
+			}
 
-	if !vnetHdr {
-		fd, err = openTunDev()
-		if err != nil {
+			fd, err = unix.Open("/dev/net/tun", os.O_RDWR, 0)
+			if err != nil {
+				return nil, fmt.Errorf("created /dev/net/tun, but still failed: %w", err)
+			}
+		} else {
 			return nil, err
 		}
-		name, err = tunSetIff(fd, nameStr, baseFlags)
-		if err != nil {
-			_ = unix.Close(fd)
-			return nil, &NameError{Name: nameStr, Underlying: err}
+	}
+
+	var req ifReq
+	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI)
+	if multiqueue {
+		req.Flags |= unix.IFF_MULTI_QUEUE
+	}
+	nameStr := c.GetString("tun.dev", "")
+	copy(req.Name[:], nameStr)
+	if err = ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
+		_ = unix.Close(fd)
+		return nil, &NameError{
+			Name:       nameStr,
+			Underlying: err,
 		}
 	}
+	name := strings.Trim(string(req.Name[:]), "\x00")
 
-	if vnetHdr {
-		l.Info("TUN offload enabled", "tso", true, "uso", usoEnabled)
-	}
-
-	t, err := newTunGeneric(c, l, fd, vnetHdr, usoEnabled, vpnNetworks)
+	t, err := newTunGeneric(c, l, fd, vpnNetworks)
 	if err != nil {
 		return nil, err
 	}
@@ -201,34 +299,20 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, multiqueue
 }
 
 // newTunGeneric does all the stuff common to different tun initialization paths. It will close your files on error.
-func newTunGeneric(c *config.C, l *slog.Logger, fd int, vnetHdr, usoEnabled bool, vpnNetworks []netip.Prefix) (*tun, error) {
-	var qs tio.QueueSet
-	var err error
-	if vnetHdr {
-		qs, err = tio.NewOffloadQueueSet(usoEnabled)
-	} else {
-		qs, err = tio.NewPollQueueSet()
-	}
-
+func newTunGeneric(c *config.C, l *slog.Logger, fd int, vpnNetworks []netip.Prefix) (*tun, error) {
+	tfd, err := newTunFd(fd)
 	if err != nil {
 		_ = unix.Close(fd)
 		return nil, err
 	}
-	err = qs.Add(fd)
-	if err != nil {
-		_ = unix.Close(fd)
-		return nil, err
-	}
-
 	t := &tun{
-		readers:                   qs,
+		tunFile:                   tfd,
+		readers:                   []*tunFile{tfd},
 		closeLock:                 sync.Mutex{},
-		vnetHdr:                   vnetHdr,
 		vpnNetworks:               vpnNetworks,
 		TXQueueLen:                c.GetInt("tun.tx_queue", 500),
 		useSystemRoutes:           c.GetBool("tun.use_system_route_table", false),
 		useSystemRoutesBufferSize: c.GetInt("tun.use_system_route_table_buffer_size", 0),
-		routeFeatureECN:           c.GetBool("tunnels.ecn", true),
 		routesFromSystem:          map[netip.Prefix]routing.Gateways{},
 		l:                         l,
 	}
@@ -326,38 +410,32 @@ func (t *tun) SupportsMultiqueue() bool {
 	return true
 }
 
-func (t *tun) NewMultiQueueReader() error {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	t.closeLock.Lock()
 	defer t.closeLock.Unlock()
 
 	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	flags := uint16(unix.IFF_TUN | unix.IFF_NO_PI | unix.IFF_MULTI_QUEUE)
-	if t.vnetHdr {
-		flags |= unix.IFF_VNET_HDR
-	}
-	if _, err = tunSetIff(fd, t.Device, flags); err != nil {
+	var req ifReq
+	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI | unix.IFF_MULTI_QUEUE)
+	copy(req.Name[:], t.Device)
+	if err = ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
 		_ = unix.Close(fd)
-		return err
+		return nil, err
 	}
 
-	if t.vnetHdr {
-		if err = ioctl(uintptr(fd), unix.TUNSETOFFLOAD, uintptr(tsoOffloadFlags)); err != nil {
-			_ = unix.Close(fd)
-			return fmt.Errorf("failed to enable offload on multiqueue tun fd: %w", err)
-		}
-	}
-
-	err = t.readers.Add(fd)
+	out, err := t.tunFile.newFriend(fd)
 	if err != nil {
 		_ = unix.Close(fd)
-		return err
+		return nil, err
 	}
 
-	return nil
+	t.readers = append(t.readers, out)
+
+	return out, nil
 }
 
 func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
@@ -525,18 +603,6 @@ func (t *tun) setDefaultRoute(cidr netip.Prefix) error {
 		Table:     unix.RT_TABLE_MAIN,
 		Type:      unix.RTN_UNICAST,
 	}
-	// Match the metric the kernel uses for its auto-installed connected
-	// route, so RouteReplace overwrites it in place instead of adding a
-	// second route at a worse metric. IPv6 connected routes are installed
-	// at metric 256 (IP6_RT_PRIO_KERN); IPv4 uses 0. Without this, the
-	// kernel route wins lookups and our MTU / AdvMSS / Features never
-	// apply on v6.
-	if cidr.Addr().Is6() {
-		nr.Priority = 256
-	}
-	if t.routeFeatureECN {
-		nr.Features |= unix.RTAX_FEATURE_ECN
-	}
 	err := netlink.RouteReplace(&nr)
 	if err != nil {
 		t.l.Warn("Failed to set default route MTU, retrying", "error", err, "cidr", cidr)
@@ -586,9 +652,6 @@ func (t *tun) addRoutes(logErrors bool) error {
 		if r.Metric > 0 {
 			nr.Priority = r.Metric
 		}
-		if t.routeFeatureECN {
-			nr.Features |= unix.RTAX_FEATURE_ECN
-		}
 
 		err := netlink.RouteReplace(&nr)
 		if err != nil {
@@ -806,10 +869,6 @@ func (t *tun) updateRoutes(r netlink.RouteUpdate) {
 	t.routeTree.Store(newTree)
 }
 
-func (t *tun) Readers() []tio.Queue {
-	return t.readers.Queues()
-}
-
 func (t *tun) Close() error {
 	t.closeLock.Lock()
 	defer t.closeLock.Unlock()
@@ -819,10 +878,34 @@ func (t *tun) Close() error {
 		t.routeChan = nil
 	}
 
+	// Signal all readers blocked in poll to wake up and exit
+	_ = t.tunFile.wakeForShutdown()
+
 	if t.ioctlFd > 0 {
 		_ = unix.Close(int(t.ioctlFd))
 		t.ioctlFd = 0
 	}
 
-	return t.readers.Close()
+	for i := range t.readers {
+		if i == 0 {
+			continue //we want to close the zeroth reader last
+		}
+		err := t.readers[i].Close()
+		if err != nil {
+			t.l.Error("error closing tun reader", "reader", i, "error", err)
+		} else {
+			t.l.Info("closed tun reader", "reader", i)
+		}
+	}
+
+	//this is t.readers[0] too
+	err := t.tunFile.Close()
+	if err != nil {
+		t.l.Error("error closing tun reader", "reader", 0, "error", err)
+	} else {
+		t.l.Info("closed tun reader", "reader", 0)
+	}
+	return err
 }
+
+func (t *tun) TunPrefixLen() int { return 0 }

overlay/tun_linux_test.go

@@ -3,9 +3,7 @@
 
 package overlay
 
-import (
-	"testing"
-)
+import "testing"
 
 var runAdvMSSTests = []struct {
 	name     string

overlay/tun_netbsd.go

@@ -6,6 +6,7 @@ package overlay
 import (
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/netip"
 	"os"
@@ -16,7 +17,6 @@ import (
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 	netroute "golang.org/x/net/route"
@@ -58,30 +58,14 @@ type addrLifetime struct {
 }
 
 type tun struct {
+	io.ReadWriteCloser
 	Device      string
 	vpnNetworks []netip.Prefix
 	MTU         int
 	Routes      atomic.Pointer[[]Route]
 	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
 	l           *slog.Logger
-	f           *os.File
 	fd          int
-
-	readBuf  []byte
-	batchRet [1]tio.Packet
-}
-
-func (t *tun) Read() ([]tio.Packet, error) {
-	n, err := t.readOne(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = tio.Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
-}
-
-func (t *tun) Readers() []tio.Queue {
-	return []tio.Queue{t}
 }
 
 var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`)
@@ -112,13 +96,12 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*t
 	}
 
 	t := &tun{
-		f:           os.NewFile(uintptr(fd), ""),
-		fd:          fd,
-		Device:      deviceName,
-		vpnNetworks: vpnNetworks,
-		MTU:         c.GetInt("tun.mtu", DefaultMTU),
-		l:           l,
-		readBuf:     make([]byte, defaultBatchBufSize),
+		ReadWriteCloser: os.NewFile(uintptr(fd), ""),
+		fd:              fd,
+		Device:          deviceName,
+		vpnNetworks:     vpnNetworks,
+		MTU:             c.GetInt("tun.mtu", DefaultMTU),
+		l:               l,
 	}
 
 	err = t.reload(c, true)
@@ -137,12 +120,12 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*t
 }
 
 func (t *tun) Close() error {
-	if t.f != nil {
-		if err := t.f.Close(); err != nil {
+	if t.ReadWriteCloser != nil {
+		if err := t.ReadWriteCloser.Close(); err != nil {
 			return fmt.Errorf("error closing tun file: %w", err)
 		}
 
-		// t.f.Close should have handled it for us but let's be extra sure
+		// Close on the os.File should have handled the fd for us but let's be extra sure
 		_ = unix.Close(t.fd)
 
 		s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_IP)
@@ -158,99 +141,6 @@ func (t *tun) Close() error {
 	return nil
 }
 
-func (t *tun) readOne(to []byte) (int, error) {
-	rc, err := t.f.SyscallConn()
-	if err != nil {
-		return 0, fmt.Errorf("failed to get syscall conn for tun: %w", err)
-	}
-
-	var errno syscall.Errno
-	var n uintptr
-	err = rc.Read(func(fd uintptr) bool {
-		// first 4 bytes is protocol family, in network byte order
-		head := [4]byte{}
-		iovecs := []syscall.Iovec{
-			{&head[0], 4},
-			{&to[0], uint64(len(to))},
-		}
-
-		n, _, errno = syscall.Syscall(syscall.SYS_READV, fd, uintptr(unsafe.Pointer(&iovecs[0])), uintptr(2))
-		if errno.Temporary() {
-			// We got an EAGAIN, EINTR, or EWOULDBLOCK, go again
-			return false
-		}
-		return true
-	})
-	if err != nil {
-		if err == syscall.EBADF || err.Error() == "use of closed file" {
-			// Go doesn't export poll.ErrFileClosing but happily reports it to us so here we are
-			// https://github.com/golang/go/blob/master/src/internal/poll/fd_poll_runtime.go#L121
-			return 0, os.ErrClosed
-		}
-		return 0, fmt.Errorf("failed to make read call for tun: %w", err)
-	}
-
-	if errno != 0 {
-		return 0, fmt.Errorf("failed to make inner read call for tun: %w", errno)
-	}
-
-	// fix bytes read number to exclude header
-	bytesRead := int(n)
-	if bytesRead < 0 {
-		return bytesRead, nil
-	} else if bytesRead < 4 {
-		return 0, nil
-	} else {
-		return bytesRead - 4, nil
-	}
-}
-
-// Write is only valid for single threaded use
-func (t *tun) Write(from []byte) (int, error) {
-	if len(from) <= 1 {
-		return 0, syscall.EIO
-	}
-
-	ipVer := from[0] >> 4
-	var head [4]byte
-	// first 4 bytes is protocol family, in network byte order
-	if ipVer == 4 {
-		head[3] = syscall.AF_INET
-	} else if ipVer == 6 {
-		head[3] = syscall.AF_INET6
-	} else {
-		return 0, fmt.Errorf("unable to determine IP version from packet")
-	}
-
-	rc, err := t.f.SyscallConn()
-	if err != nil {
-		return 0, err
-	}
-
-	var errno syscall.Errno
-	var n uintptr
-	err = rc.Write(func(fd uintptr) bool {
-		iovecs := []syscall.Iovec{
-			{&head[0], 4},
-			{&from[0], uint64(len(from))},
-		}
-
-		n, _, errno = syscall.Syscall(syscall.SYS_WRITEV, fd, uintptr(unsafe.Pointer(&iovecs[0])), uintptr(2))
-		// According to NetBSD documentation for TUN, writes will only return errors in which
-		// this packet will never be delivered so just go on living life.
-		return true
-	})
-	if err != nil {
-		return 0, err
-	}
-
-	if errno != 0 {
-		return 0, errno
-	}
-
-	return int(n) - 4, err
-}
-
 func (t *tun) addIp(cidr netip.Prefix) error {
 	if cidr.Addr().Is4() {
 		var req ifreqAlias4
@@ -411,8 +301,8 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented for netbsd")
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for netbsd")
 }
 
 func (t *tun) addRoutes(logErrors bool) error {
@@ -568,3 +458,7 @@ func delRoute(prefix netip.Prefix, gateways []netip.Prefix) error {
 
 	return nil
 }
+
+// TunPrefixLen reports the 4-byte BSD AF_INET / AF_INET6 protocol-family
+// marker the kernel prepends on read and expects on write.
+func (t *tun) TunPrefixLen() int { return 4 }

overlay/tun_no_prefix.go

@@ -0,0 +1,10 @@
+//go:build (!darwin && !ios && !freebsd && !openbsd && !netbsd) || e2e_testing
+
+package overlay
+
+// StampTunPrefix is a no-op on platforms whose tun devices have no
+// protocol-family marker. WireBuffer only invokes it when its prefixLen
+// is non-zero, so this should never be reached on these platforms.
+func StampTunPrefix(buf []byte) error {
+	return nil
+}

overlay/tun_openbsd.go

@@ -6,6 +6,7 @@ package overlay
 import (
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/netip"
 	"os"
@@ -16,7 +17,6 @@ import (
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/util"
 	netroute "golang.org/x/net/route"
@@ -49,28 +49,14 @@ type ifreq struct {
 }
 
 type tun struct {
+	io.ReadWriteCloser
 	Device      string
 	vpnNetworks []netip.Prefix
 	MTU         int
 	Routes      atomic.Pointer[[]Route]
 	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
 	l           *slog.Logger
-	f           *os.File
 	fd          int
-	// cache out buffer since we need to prepend 4 bytes for tun metadata
-	out []byte
-
-	readBuf  []byte
-	batchRet [1]tio.Packet
-}
-
-func (t *tun) Read() ([]tio.Packet, error) {
-	n, err := t.readOne(t.readBuf)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0] = tio.Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
 }
 
 var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`)
@@ -101,13 +87,12 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*t
 	}
 
 	t := &tun{
-		f:           os.NewFile(uintptr(fd), ""),
-		fd:          fd,
-		Device:      deviceName,
-		vpnNetworks: vpnNetworks,
-		MTU:         c.GetInt("tun.mtu", DefaultMTU),
-		l:           l,
-		readBuf:     make([]byte, defaultBatchBufSize),
+		ReadWriteCloser: os.NewFile(uintptr(fd), ""),
+		fd:              fd,
+		Device:          deviceName,
+		vpnNetworks:     vpnNetworks,
+		MTU:             c.GetInt("tun.mtu", DefaultMTU),
+		l:               l,
 	}
 
 	err = t.reload(c, true)
@@ -126,55 +111,17 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*t
 }
 
 func (t *tun) Close() error {
-	if t.f != nil {
-		if err := t.f.Close(); err != nil {
+	if t.ReadWriteCloser != nil {
+		if err := t.ReadWriteCloser.Close(); err != nil {
 			return fmt.Errorf("error closing tun file: %w", err)
 		}
 
-		// t.f.Close should have handled it for us but let's be extra sure
+		// Close on the os.File should have handled the fd for us but let's be extra sure
 		_ = unix.Close(t.fd)
 	}
 	return nil
 }
 
-func (t *tun) readOne(to []byte) (int, error) {
-	buf := make([]byte, len(to)+4)
-
-	n, err := t.f.Read(buf)
-
-	copy(to, buf[4:])
-	return n - 4, err
-}
-
-// Write is only valid for single threaded use
-func (t *tun) Write(from []byte) (int, error) {
-	buf := t.out
-	if cap(buf) < len(from)+4 {
-		buf = make([]byte, len(from)+4)
-		t.out = buf
-	}
-	buf = buf[:len(from)+4]
-
-	if len(from) == 0 {
-		return 0, syscall.EIO
-	}
-
-	// Determine the IP Family for the NULL L2 Header
-	ipVer := from[0] >> 4
-	if ipVer == 4 {
-		buf[3] = syscall.AF_INET
-	} else if ipVer == 6 {
-		buf[3] = syscall.AF_INET6
-	} else {
-		return 0, fmt.Errorf("unable to determine IP version from packet")
-	}
-
-	copy(buf[4:], from)
-
-	n, err := t.f.Write(buf)
-	return n - 4, err
-}
-
 func (t *tun) addIp(cidr netip.Prefix) error {
 	if cidr.Addr().Is4() {
 		var req ifreqAlias4
@@ -327,8 +274,8 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented for openbsd")
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for openbsd")
 }
 
 func (t *tun) addRoutes(logErrors bool) error {
@@ -379,10 +326,6 @@ func (t *tun) deviceBytes() (o [16]byte) {
 	return
 }
 
-func (t *tun) Readers() []tio.Queue {
-	return []tio.Queue{t}
-}
-
 func addRoute(prefix netip.Prefix, gateways []netip.Prefix) error {
 	sock, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
 	if err != nil {
@@ -488,3 +431,7 @@ func delRoute(prefix netip.Prefix, gateways []netip.Prefix) error {
 
 	return nil
 }
+
+// TunPrefixLen reports the 4-byte BSD AF_INET / AF_INET6 protocol-family
+// marker the kernel prepends on read and expects on write.
+func (t *tun) TunPrefixLen() int { return 4 }

overlay/tun_tester.go

@@ -14,7 +14,6 @@ import (
 
 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/udp"
 )
@@ -29,8 +28,6 @@ type TestTun struct {
 	closed    atomic.Bool
 	rxPackets chan []byte // Packets to receive into nebula
 	TxPackets chan []byte // Packets transmitted outside by nebula
-
-	batchRet [1]tio.Packet
 }
 
 func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*TestTun, error) {
@@ -51,9 +48,6 @@ func newTun(c *config.C, l *slog.Logger, vpnNetworks []netip.Prefix, _ bool) (*T
 		l:           l,
 		rxPackets:   make(chan []byte, 10),
 		TxPackets:   make(chan []byte, 10),
-		batchRet: [1]tio.Packet{
-			tio.Packet{Bytes: make([]byte, udp.MTU)},
-		},
 	}, nil
 }
 
@@ -168,17 +162,7 @@ func (t *TestTun) Close() error {
 	return nil
 }
 
-func (t *TestTun) Read() ([]tio.Packet, error) {
-	t.batchRet[0].Bytes = t.batchRet[0].Bytes[:udp.MTU]
-	n, err := t.read(t.batchRet[0].Bytes)
-	if err != nil {
-		return nil, err
-	}
-	t.batchRet[0].Bytes = t.batchRet[0].Bytes[:n]
-	return t.batchRet[:], nil
-}
-
-func (t *TestTun) read(b []byte) (int, error) {
+func (t *TestTun) Read(b []byte) (int, error) {
 	p, ok := <-t.rxPackets
 	if !ok {
 		return 0, os.ErrClosed
@@ -193,14 +177,12 @@ func (t *TestTun) read(b []byte) (int, error) {
 	return n, nil
 }
 
-func (t *TestTun) Readers() []tio.Queue {
-	return []tio.Queue{t}
-}
-
 func (t *TestTun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *TestTun) NewMultiQueueReader() error {
-	return fmt.Errorf("TODO: multiqueue not implemented")
+func (t *TestTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented")
 }
+
+func (t *TestTun) TunPrefixLen() int { return 0 }