v1.11.1 (#1854 )

Prepare the v1.11.1 CHANGELOG updates
release: retry the STS assume until the secret key survives Windows (#1856 )
2026-09-30 20:36:38 +02:00 · 2026-08-21 15:23:25 -04:00 · 2026-08-21 11:03:53 -05:00 · 2026-08-20 16:52:50 -04:00 · 2026-08-20 16:52:36 -04:00 · 2026-08-20 14:24:11 -04:00
150 changed files with 1255 additions and 14914 deletions
@@ -20,45 +20,44 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v7
-      with:
-        go-version: '1.26'
-        check-latest: true
-
-    - name: Smoke Docker
-      run: make smoke-docker
-
-    - name: Smoke Docker IPv6 overlay
-      run: make smoke-docker-ipv6
-
-    - name: Smoke Relay Docker
-      run: make smoke-relay-docker
-
-    - name: Smoke Docker boringcrypto
-      run: make boringcrypto smoke-docker
-
-    - name: Smoke Docker fips140
-      run: make fips140-all GOALS=smoke-docker
-
-    timeout-minutes: 10
-
-  smoke-self:
-    name: Run self traffic smoke test on macOS
-    runs-on: macos-latest
-    steps:
-
-    - uses: actions/checkout@v7
-
    - uses: actions/setup-go@v7
      with:
        go-version: '1.26'
        check-latest: true

    - name: build
-      run: make bin
+      run: make bin-docker CGO_ENABLED=1 BUILD_ARGS=-race

-    - name: run smoke-self
+    - name: setup docker image
      working-directory: ./.github/workflows/smoke
-      run: ./smoke-self.sh
+      run: ./build.sh
+
+    - name: run smoke
+      working-directory: ./.github/workflows/smoke
+      run: ./smoke.sh
+
+    - name: setup docker image ipv6
+      working-directory: ./.github/workflows/smoke
+      run: SMOKE_OVERLAY_IPV6=1 ./build.sh
+
+    - name: run smoke ipv6
+      working-directory: ./.github/workflows/smoke
+      run: SMOKE_OVERLAY_IPV6=1 ./smoke.sh
+
+    - name: setup relay docker image
+      working-directory: ./.github/workflows/smoke
+      run: ./build-relay.sh
+
+    - name: run smoke relay
+      working-directory: ./.github/workflows/smoke
+      run: ./smoke-relay.sh
+
+    - name: setup docker image for P256
+      working-directory: ./.github/workflows/smoke
+      run: NAME="smoke-p256" CURVE=P256 ./build.sh
+
+    - name: run smoke-p256
+      working-directory: ./.github/workflows/smoke
+      run: NAME="smoke-p256" ./smoke.sh

    timeout-minutes: 10
@@ -1,130 +0,0 @@
-#!/bin/bash
-
-# A host must be able to reach its own overlay address. Where the kernel sends
-# that traffic through the tun rather than over loopback, nebula sees it and
-# hands it straight back (immediatelyForwardToSelf), and whether the kernel
-# accepts what comes back is only answerable against a real kernel. Runs one
-# nebula on this machine as root and aims every probe at its own address.
-
-set -e -x
-
-set -o pipefail
-
-V4=192.0.2.1
-V6=2001:db8::1
-
-case "$(uname -s)" in
-    Darwin) TUN_DEV=utun ;;
-    *) TUN_DEV=tun0 ;;
-esac
-
-ROOT="$(cd ../../.. && pwd)"
-
-rm -rf build/self
-mkdir -p build/self
-cd build/self
-
-cleanup() {
-    echo
-    echo " *** cleanup"
-    echo
-
-    set +e
-    if [ -n "$NEBULA_PID" ]
-    then
-        sudo kill "$NEBULA_PID"
-    fi
-    { kill $(jobs -p); wait; } 2>/dev/null
-    sed 's/^/  [self]  /' nebula.log
-}
-
-trap cleanup EXIT
-
-# perl is on every platform this runs on; timeout(1) is not.
-alarm() {
-    perl -e 'alarm shift; exec @ARGV' "$@"
-}
-
-RESULTS=""
-FAILED=""
-probe() {
-    local name="$1"
-    shift
-    if "$@"
-    then
-        RESULTS="$RESULTS $name=ok"
-    else
-        RESULTS="$RESULTS $name=FAIL"
-        FAILED="$FAILED $name"
-    fi
-}
-
-# Send one datagram, then wait for the listener to have written it out.
-udp_probe() {
-    echo self | alarm 5 nc -u -w1 "$1" 3000 || true
-    set +x
-    for _ in $(seq 1 20)
-    do
-        if grep -q self "$2"
-        then
-            set -x
-            return 0
-        fi
-        sleep 0.25
-    done
-    set -x
-    return 1
-}
-
-"$ROOT/nebula-cert" ca -name "Smoke Test"
-"$ROOT/nebula-cert" sign -name self -networks "$V4/24,$V6/64"
-
-HOST=self AM_LIGHTHOUSE=true TUN_DEV="$TUN_DEV" ../../genconfig.sh >self.yml
-
-"$ROOT/nebula" -config self.yml -test
-
-sudo -v
-sudo "$ROOT/nebula" -config self.yml >nebula.log 2>&1 &
-NEBULA_PID=$!
-
-for _ in $(seq 1 40)
-do
-    ifconfig | grep "inet6 $V6 " >/dev/null && break
-    sleep 0.25
-done
-ifconfig | grep "inet $V4 "
-ifconfig | grep "inet6 $V6 "
-
-nc -l "$V4" 2000 >/dev/null &
-nc -l "$V6" 2000 >/dev/null &
-nc -u -l "$V4" 3000 >udp4.txt &
-nc -u -l "$V6" 3000 >udp6.txt &
-sleep 1
-
-set +x
-echo
-echo " *** Testing self traffic from $V4"
-echo
-set -x
-probe icmp4 alarm 5 ping -c1 "$V4"
-probe tcp4 alarm 5 nc -z "$V4" 2000
-probe udp4 udp_probe "$V4" udp4.txt
-
-set +x
-echo
-echo " *** Testing self traffic from $V6"
-echo
-set -x
-probe icmp6 alarm 5 ping6 -c1 "$V6"
-probe tcp6 alarm 5 nc -z "$V6" 2000
-probe udp6 udp_probe "$V6" udp6.txt
-
-set +x
-echo
-echo " *** self traffic:$RESULTS"
-echo
-if [ -n "$FAILED" ]
-then
-    echo "self traffic failed:$FAILED" >&2
-    exit 1
-fi
@@ -58,14 +58,9 @@ jobs:
          e2e-cmd: make e2evv
        - name: linux-boringcrypto
          os: ubuntu-latest
-          build-cmd: make boringcrypto
-          test-cmd: make boringcrypto test
-          e2e-cmd: make boringcrypto e2evv
-        - name: linux-fips140
-          os: ubuntu-latest
-          build-cmd: make fips140-all
-          test-cmd: make fips140-all GOALS=test
-          e2e-cmd: make fips140-all GOALS=e2evv
+          build-cmd: make bin-boringcrypto
+          test-cmd: make test-boringcrypto
+          e2e-cmd: make e2e GOEXPERIMENT=boringcrypto CGO_ENABLED=1 TEST_ENV="TEST_LOGS=1" TEST_FLAGS="-v -ldflags -checklinkname=0"
        - name: linux-pkcs11
          os: ubuntu-latest
          build-cmd: make bin-pkcs11
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

 ## [Unreleased]

+## [1.11.1] - 2026-08-21
+
+See the [v1.11.1](https://github.com/slackhq/nebula/milestone/30?closed=1) milestone for a complete list of changes.
+
 ### Changed

 - IPv6 packets whose next header is a protocol Nebula does not parse (SCTP, GRE, IP-in-IP, etc.) are now
@@ -15,11 +19,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  their true protocol, so only a `proto: any` rule allows them. If you carry one of these protocols over the
  overlay, confirm a `proto: any` rule covers it before upgrading, it may have been passing only through this
  bypass. (#1840)
+- Drop the dependency on `github.com/cyberdelia/go-metrics-graphite`, which has been unmaintained for over ten
+  years, by inlining the small amount of code Nebula used. (#1832)

 ### Fixed

 - The ICMPv6 type was read from the wrong byte when classifying IPv6 packets, so the echo identifier used
  for conntrack was never picked up. (#1840)
+- Enforce outbound message counter limits so a tunnel is rehandshaked before the counter can wrap, preventing
+  nonce reuse. This is unreachable in practice, but is enforced as a defense-in-depth measure. (#1841)
+- Prevent `nebula-cert ca` from running out of memory on 32bit systems when generating encrypted private keys. (#1834)
+- Tolerate `ErrDumpInterrupted` when listing tun addresses on Linux, so a transient interrupted netlink dump
+  no longer aborts startup. (#1835)

 ## [1.11.0] - 2026-07-23

@@ -884,7 +895,9 @@ created.)

 - Initial public release.

-[Unreleased]: https://github.com/slackhq/nebula/compare/v1.10.3...HEAD
+[Unreleased]: https://github.com/slackhq/nebula/compare/v1.11.1...HEAD
+[1.11.1]: https://github.com/slackhq/nebula/releases/tag/v1.11.1
+[1.11.0]: https://github.com/slackhq/nebula/releases/tag/v1.11.0
 [1.10.3]: https://github.com/slackhq/nebula/releases/tag/v1.10.3
 [1.10.2]: https://github.com/slackhq/nebula/releases/tag/v1.10.2
 [1.10.1]: https://github.com/slackhq/nebula/releases/tag/v1.10.1
@@ -72,17 +72,6 @@ ALL_CROSS_LINUX_ARM   = linux-arm-5 linux-arm-6 linux-arm-7 linux-arm64
 ALL_CROSS_LINUX_MIPS  = linux-mips linux-mipsle linux-mips64 linux-mips64le linux-mips-softfloat
 ALL_CROSS_LINUX_OTHER = linux-386 linux-ppc64le linux-riscv64 linux-loong64

-# Based on section 2.2 of the Go Cryptographic Module CVMP Security Policy #5247
-ALL_FIPS140 = linux-amd64-fips140 \
-	linux-arm64-fips140 \
-	windows-amd64-fips140 \
-	windows-arm64-fips140 \
-	darwin-arm64-fips140 \
-	freebsd-amd64-fips140 \
-	linux-arm-7-fips140 \
-	linux-mips64-fips140 \
-	linux-ppc64le-fips140
-
 e2e:
 	$(TEST_ENV) go test -tags=e2e_testing -count=1 $(TEST_FLAGS) ./e2e

@@ -148,8 +137,6 @@ release-netbsd: $(ALL_NETBSD:%=build/nebula-%.tar.gz)

 release-boringcrypto: build/nebula-linux-$(shell go env GOARCH)-boringcrypto.tar.gz

-release-fips140: $(ALL_FIPS140:%=build/nebula-%.tar.gz)
-
 BUILD_ARGS += -trimpath

 bin-windows: build/windows-amd64/nebula.exe build/windows-amd64/nebula-cert.exe
@@ -170,24 +157,17 @@ bin-freebsd-arm64: build/freebsd-arm64/nebula build/freebsd-arm64/nebula-cert
 bin-boringcrypto: build/linux-$(shell go env GOARCH)-boringcrypto/nebula build/linux-$(shell go env GOARCH)-boringcrypto/nebula-cert
 	mv $? .

-bin-fips140: build/linux-$(shell go env GOARCH)-fips140/nebula build/linux-$(shell go env GOARCH)-fips140/nebula-cert
-	mv $? .
-
 bin-pkcs11: BUILD_ARGS += -tags pkcs11
 bin-pkcs11: CGO_ENABLED = 1
 bin-pkcs11: bin

-# Build with the pprof debug server (serves on :6060). See startPprofServer.
-debug: BUILD_ARGS += -tags debug
-debug: bin
-
 bin:
-	$(GOENV) go build $(BUILD_ARGS) -ldflags "$(LDFLAGS)" -o ./nebula${NEBULA_CMD_SUFFIX} ${NEBULA_CMD_PATH}
-	$(GOENV) go build $(BUILD_ARGS) -ldflags "$(LDFLAGS)" -o ./nebula-cert${NEBULA_CMD_SUFFIX} ./cmd/nebula-cert
+	go build $(BUILD_ARGS) -ldflags "$(LDFLAGS)" -o ./nebula${NEBULA_CMD_SUFFIX} ${NEBULA_CMD_PATH}
+	go build $(BUILD_ARGS) -ldflags "$(LDFLAGS)" -o ./nebula-cert${NEBULA_CMD_SUFFIX} ./cmd/nebula-cert

 install:
-	$(GOENV) go install $(BUILD_ARGS) -ldflags "$(LDFLAGS)" ${NEBULA_CMD_PATH}
-	$(GOENV) go install $(BUILD_ARGS) -ldflags "$(LDFLAGS)" ./cmd/nebula-cert
+	go install $(BUILD_ARGS) -ldflags "$(LDFLAGS)" ${NEBULA_CMD_PATH}
+	go install $(BUILD_ARGS) -ldflags "$(LDFLAGS)" ./cmd/nebula-cert

 build/linux-arm-%: GOENV += GOARM=$(word 3, $(subst -, ,$*))
 build/linux-mips-%: GOENV += GOMIPS=$(word 3, $(subst -, ,$*))
@@ -198,11 +178,8 @@ build/linux-mips-softfloat/%: LDFLAGS += -s -w
 # boringcrypto
 build/linux-amd64-boringcrypto/%: GOENV += GOEXPERIMENT=boringcrypto CGO_ENABLED=1
 build/linux-arm64-boringcrypto/%: GOENV += GOEXPERIMENT=boringcrypto CGO_ENABLED=1
-
-# fips140
-FIPSVERSION = v1.0.0
-$(foreach _rule, $(ALL_FIPS140), build/$(_rule)/%): GOENV += GOFIPS140=$(FIPSVERSION)
-$(foreach _rule, $(ALL_FIPS140), build/$(_rule)/%): BUILD_ARGS += -tags fips140enforce
+build/linux-amd64-boringcrypto/%: LDFLAGS += -checklinkname=0
+build/linux-arm64-boringcrypto/%: LDFLAGS += -checklinkname=0

 build/%/nebula: .FORCE
 	GOOS=$(firstword $(subst -, , $*)) \
@@ -233,7 +210,10 @@ vet:
 	go vet $(VET_FLAGS) -v ./...

 test:
-	$(TEST_ENV) go test $(TEST_FLAGS) -v ./...
+	go test -v ./...
+
+test-boringcrypto:
+	GOEXPERIMENT=boringcrypto CGO_ENABLED=1 go test -ldflags "-checklinkname=0" -v ./...

 test-pkcs11:
 	CGO_ENABLED=1 go test -v -tags pkcs11 ./...
@@ -276,75 +256,29 @@ ifeq ($(words $(MAKECMDGOALS)),1)
 	@$(MAKE) service ${.DEFAULT_GOAL} --no-print-directory
 endif

-# Useful to chain together, like:
-# - make fips140 e2evv
-# - make fips140 smoke-docker
-# Use `release-fips140` to build release binaries
-fips140:
-	@echo > $(NULL_FILE)
-ifeq ($(strip $(GOFIPS140)),)
-	$(eval GOFIPS140 = $(FIPSVERSION))
-endif
-	$(eval GOENV += GOFIPS140=$(GOFIPS140))
-	$(eval BUILD_ARGS += -tags fips140enforce)
-	$(eval TEST_ENV += $(GOENV))
-	$(eval CURVE = P256)
-ifeq ($(words $(MAKECMDGOALS)),1)
-	@$(MAKE) fips140 GOFIPS140=$(GOFIPS140) ${.DEFAULT_GOAL} --no-print-directory
-endif
-
-# To test the future pending module, use like `make fips140-latest test`
-ALL_GOFIPS140 = v1.0.0 v1.26.0 latest
-define FIPS140_rule
-fips140-$(1): GOFIPS140 = $(1)
-fips140-$(1): fips140
-endef
-$(foreach _rule, $(ALL_GOFIPS140), $(eval $(call FIPS140_rule,$(_rule))))
-
-# Iterate and run the goals for all fips versions, like `make fips140-all GOALS=test`
-fips140-all:
-	@$(foreach _v,$(ALL_GOFIPS140),$(MAKE) fips140-$(_v) $(GOALS) &&) true
-
-# Useful to chain together, like:
-# - make boringcrypto e2evv
-# - make boringcrypto smoke-docker
-# Use `release-boringcrypto` or `bin-boringcrypto` to build release binaries
-boringcrypto:
-	@echo > $(NULL_FILE)
-	$(eval GOENV += GOEXPERIMENT=boringcrypto CGO_ENABLED=1)
-	$(eval TEST_ENV += $(GOENV))
-	$(eval CURVE = P256)
-ifeq ($(words $(MAKECMDGOALS)),1)
-	@$(MAKE) boringcrypto ${.DEFAULT_GOAL} --no-print-directory
-endif
-
 bin-docker: bin build/linux-amd64/nebula build/linux-amd64/nebula-cert

-smoke-docker: BUILD_ARGS += -race
-smoke-docker: GOENV += CGO_ENABLED=1
 smoke-docker: bin-docker
-	# This is so we can limit `fips140` smoke test to just P256 curve.
-	if [ "$(CURVE)" != "P256" ]; then cd .github/workflows/smoke/ && $(GOENV) ./build.sh; fi
-	if [ "$(CURVE)" != "P256" ]; then cd .github/workflows/smoke/ && $(GOENV) ./smoke.sh; fi
-	cd .github/workflows/smoke/ && $(GOENV) NAME="smoke-p256" CURVE="P256" ./build.sh
-	cd .github/workflows/smoke/ && $(GOENV) NAME="smoke-p256" ./smoke.sh
+	cd .github/workflows/smoke/ && ./build.sh
+	cd .github/workflows/smoke/ && ./smoke.sh
+	cd .github/workflows/smoke/ && NAME="smoke-p256" CURVE="P256" ./build.sh
+	cd .github/workflows/smoke/ && NAME="smoke-p256" ./smoke.sh

-smoke-relay-docker: BUILD_ARGS += -race
-smoke-relay-docker: GOENV += CGO_ENABLED=1
 smoke-relay-docker: bin-docker
-	cd .github/workflows/smoke/ && $(GOENV) ./build-relay.sh
-	cd .github/workflows/smoke/ && $(GOENV) ./smoke-relay.sh
+	cd .github/workflows/smoke/ && ./build-relay.sh
+	cd .github/workflows/smoke/ && ./smoke-relay.sh

 smoke-docker-ipv6: export SMOKE_OVERLAY_IPV6 = 1
 smoke-docker-ipv6: smoke-docker

-smoke-self: bin
-	cd .github/workflows/smoke/ && ./smoke-self.sh
+smoke-docker-race: BUILD_ARGS = -race
+smoke-docker-race: CGO_ENABLED = 1
+smoke-docker-race: smoke-docker

 smoke-vagrant/%: bin-docker build/%/nebula
 	cd .github/workflows/smoke/ && ./build.sh $*
 	cd .github/workflows/smoke/ && ./smoke-vagrant.sh $*

 .FORCE:
-.PHONY: all all-linux all-freebsd all-openbsd all-netbsd all-darwin all-windows all-cross-linux all-cross-linux-arm all-cross-linux-mips all-cross-linux-other all-cross-darwin all-cross-windows bench bench-cpu bench-cpu-long bin bin-windows bin-windows-arm64 bin-darwin bin-freebsd bin-freebsd-arm64 bin-boringcrypto bin-fips140 bin-pkcs11 bin-docker boringcrypto build-test-mobile debug docker e2e e2ev e2evv e2evvv e2evvvv e2e-bench fips140 fips140-all $(ALL_GOFIPS140:%=fips140-%) install proto release release-linux release-freebsd release-openbsd release-netbsd release-boringcrypto release-fips140 service smoke-docker smoke-relay-docker smoke-docker-ipv6 smoke-self test test-pkcs11 test-cov-html vet smoke-vagrant/%
+.PHONY: all all-linux all-freebsd all-openbsd all-netbsd all-darwin all-windows all-cross-linux all-cross-linux-arm all-cross-linux-mips all-cross-linux-other all-cross-darwin all-cross-windows bench bench-cpu bench-cpu-long bin build-test-mobile e2e e2ev e2evv e2evvv e2evvvv proto release service smoke-docker smoke-docker-race test test-cov-html smoke-vagrant/%
 .DEFAULT_GOAL := bin
@@ -145,27 +145,17 @@ To build nebula for a specific platform (ex, Windows):

 See the [Makefile](Makefile) for more details on build targets

-## Curve P256 and FIPS 140-3 mode
+## Curve P256 and BoringCrypto

 The default curve used for cryptographic handshakes and signatures is Curve25519. This is the recommended setting for most users. If your deployment has certain compliance requirements, you have the option of creating your CA using `nebula-cert ca -curve P256` to use NIST Curve P256. The CA will then sign certificates using ECDSA P256, and any hosts using these certificates will use P256 for ECDH handshakes.

-Nebula can be built to support the [FIPS 140-3](https://go.dev/doc/security/fips140) mode of Go by running either of the following make targets. (This sets GOFIPS140=v1.0.0, which must be done at compile time so that the correct AES-GCM can be used for FIPS 140-3 enforcement mode).
-
-```sh
-make fips140
-make fips140 test
-make release-fips140
-```
-
-Nebula can also be built using the [BoringCrypto GOEXPERIMENT](https://github.com/golang/go/blob/go1.20/src/crypto/internal/boring/README.md) by running either of the following make targets.
+In addition, Nebula can be built using the [BoringCrypto GOEXPERIMENT](https://github.com/golang/go/blob/go1.20/src/crypto/internal/boring/README.md) by running either of the following make targets:

 ```sh
 make bin-boringcrypto
 make release-boringcrypto
 ```

-NOTE: boringcrypto support is deprecated and will be removed in the next release. Users should migrate to the native FIPS 140-3 mode described above.
-
 This is not the recommended default deployment, but may be useful based on your compliance requirements.

 ## Credits
@@ -3,9 +3,7 @@ package main
 import (
 	"crypto/ecdsa"
 	"crypto/elliptic"
-	"crypto/fips140"
 	"crypto/rand"
-	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -46,13 +44,6 @@ type caFlags struct {
 	subnets *string
 }

-func defaultCurve() string {
-	if fips140.Enforced() {
-		return "P256"
-	}
-	return "25519"
-}
-
 func newCaFlags() *caFlags {
 	// prevent running out of memory on 32-bit systems by defaulting to
 	// RFC9106's recommendation for memory-constrained environments
@@ -83,7 +74,7 @@ func newCaFlags() *caFlags {
 	cf.argonParallelism = cf.set.Uint("argon-parallelism", 4, "Optional: Argon2 parallelism parameter used for encrypted private key passphrase")
 	cf.argonIterations = cf.set.Uint("argon-iterations", defaultArgonIterations, "Optional: Argon2 iterations parameter used for encrypted private key passphrase")
 	cf.encryption = cf.set.Bool("encrypt", false, "Optional: prompt for passphrase and write out-key in an encrypted format")
-	cf.curve = cf.set.String("curve", defaultCurve(), "EdDSA/ECDSA Curve (25519, P256)")
+	cf.curve = cf.set.String("curve", "25519", "EdDSA/ECDSA Curve (25519, P256)")
 	cf.p11url = p11Flag(cf.set)

 	cf.ips = cf.set.String("ips", "", "Deprecated, see -networks")
@@ -268,9 +259,6 @@ func ca(args []string, out io.Writer, errOut io.Writer, pr PasswordReader) error
 	} else {
 		switch *cf.curve {
 		case "25519", "X25519", "Curve25519", "CURVE25519":
-			if fips140.Enforced() {
-				return errors.New("use of Curve25519 is not allowed in FIPS 140-only mode")
-			}
 			curve = cert.Curve_CURVE25519
 			pub, rawPriv, err = ed25519.GenerateKey(rand.Reader)
 			if err != nil {
@@ -1,5 +0,0 @@
-//go:build fips140enforce
-
-//go:debug fips140=only
-
-package main
@@ -1,8 +1,6 @@
 package main

 import (
-	"crypto/fips140"
-	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -26,7 +24,7 @@ func newKeygenFlags() *keygenFlags {
 	cf.set.Usage = func() {}
 	cf.outPubPath = cf.set.String("out-pub", "", "Required: path to write the public key to")
 	cf.outKeyPath = cf.set.String("out-key", "", "Required: path to write the private key to")
-	cf.curve = cf.set.String("curve", defaultCurve(), "ECDH Curve (25519, P256)")
+	cf.curve = cf.set.String("curve", "25519", "ECDH Curve (25519, P256)")
 	cf.p11url = p11Flag(cf.set)
 	return &cf
 }
@@ -63,9 +61,6 @@ func keygen(args []string, out io.Writer, errOut io.Writer) error {
 	} else {
 		switch *cf.curve {
 		case "25519", "X25519", "Curve25519", "CURVE25519":
-			if fips140.Enforced() {
-				return errors.New("use of Curve25519 is not allowed in FIPS 140-only mode")
-			}
 			pub, rawPriv = x25519Keypair()
 			curve = cert.Curve_CURVE25519
 		case "P256":
@@ -2,7 +2,6 @@ package main

 import (
 	"crypto/ecdh"
-	"crypto/fips140"
 	"crypto/rand"
 	"errors"
 	"flag"
@@ -269,10 +268,6 @@ func signCert(args []string, out io.Writer, errOut io.Writer, pr PasswordReader)
 		}(p11Client)
 	}

-	if fips140.Enforced() && curve == cert.Curve_CURVE25519 {
-		return errors.New("use of Curve25519 is not allowed in FIPS 140-only mode")
-	}
-
 	if *sf.inPubPath != "" {
 		var pubCurve cert.Curve
 		rawPub, err := readInput("in-pub", *sf.inPubPath, &claims)
@@ -1,5 +0,0 @@
-//go:build fips140enforce
-
-//go:debug fips140=only
-
-package main
@@ -1,5 +0,0 @@
-//go:build fips140enforce
-
-//go:debug fips140=only
-
-package main
@@ -105,18 +105,11 @@ func (cm *connectionManager) getInactivityTimeout() time.Duration {
 }

 func (cm *connectionManager) In(h *HostInfo) {
-	h.markIn()
+	h.in.Store(true)
 }

-// OutNoRebind records outbound traffic without consuming the rebind epoch, for relayed sends: the direct path
-// to the relay consumes the edge, the via send must not.
-func (cm *connectionManager) OutNoRebind(h *HostInfo) {
-	h.markOutOnly()
-}
-
-// Out records outbound traffic and reports whether we rebound since this tunnel last sent
-func (cm *connectionManager) Out(h *HostInfo) bool {
-	return h.markOut(cm.intf.rebindEpoch.Load())
+func (cm *connectionManager) Out(h *HostInfo) {
+	h.out.Store(true)
 }

 func (cm *connectionManager) RelayUsed(localIndex uint32) {
@@ -135,7 +128,8 @@ func (cm *connectionManager) RelayUsed(localIndex uint32) {
 // getAndResetTrafficCheck returns if there was any inbound or outbound traffic within the last tick and
 // resets the state for this local index
 func (cm *connectionManager) getAndResetTrafficCheck(h *HostInfo, now time.Time) (bool, bool) {
-	in, out := h.takeTraffic()
+	in := h.in.Swap(false)
+	out := h.out.Swap(false)
 	if in || out {
 		h.lastUsed = now
 	}
@@ -352,7 +346,7 @@ func (cm *connectionManager) makeTrafficDecision(localIndex uint32, now time.Tim
 				"tunnelCheck", m{"state": "alive", "method": "passive"},
 			)
 		}
-		hostinfo.setPendingDeletion(false)
+		hostinfo.pendingDeletion.Store(false)

 		if mainHostInfo {
 			decision = tryRehandshake
@@ -375,7 +369,7 @@ func (cm *connectionManager) makeTrafficDecision(localIndex uint32, now time.Tim
 		return decision, hostinfo, primary
 	}

-	if hostinfo.isPendingDeletion() {
+	if hostinfo.pendingDeletion.Load() {
 		// We have already sent a test packet and nothing was returned, this hostinfo is dead
 		hostinfo.logger(cm.l).Info("Tunnel status",
 			"tunnelCheck", m{"state": "dead", "method": "active"},
@@ -426,7 +420,7 @@ func (cm *connectionManager) makeTrafficDecision(localIndex uint32, now time.Tim
 		}
 	}

-	hostinfo.setPendingDeletion(true)
+	hostinfo.pendingDeletion.Store(true)
 	cm.trafficTimer.Add(hostinfo.localIndexId, cm.pendingDeletionInterval)
 	return decision, hostinfo, nil
 }
@@ -86,25 +86,25 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 	// We saw traffic out to vpnIp
 	nc.Out(hostinfo)
 	nc.In(hostinfo)
-	assert.False(t, hostinfo.isPendingDeletion())
+	assert.False(t, hostinfo.pendingDeletion.Load())
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
-	assert.True(t, hostinfo.sentSinceCheck())
-	assert.True(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.True(t, hostinfo.out.Load())
+	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())
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	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)
-	assert.True(t, hostinfo.sentSinceCheck())
+	assert.True(t, hostinfo.out.Load())
 	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
-	assert.True(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.True(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])

@@ -168,33 +168,33 @@ func Test_NewConnectionManagerTest2(t *testing.T) {
 	// We saw traffic out to vpnIp
 	nc.Out(hostinfo)
 	nc.In(hostinfo)
-	assert.True(t, (hostinfo.state.Load()&stateIn != 0))
-	assert.True(t, hostinfo.sentSinceCheck())
-	assert.False(t, hostinfo.isPendingDeletion())
+	assert.True(t, hostinfo.in.Load())
+	assert.True(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.pendingDeletion.Load())
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])
 	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())
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	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())
-	assert.True(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.True(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])

 	// We saw traffic, should no longer be pending deletion
 	nc.In(hostinfo)
 	nc.doTrafficCheck(hostinfo.localIndexId, p, nb, out, time.Now())
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.False(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])
 }
@@ -326,31 +326,31 @@ func Test_NewConnectionManager_DisconnectInactive(t *testing.T) {
 	// Do a traffic check tick, in and out should be cleared but should not be pending deletion
 	nc.Out(hostinfo)
 	nc.In(hostinfo)
-	assert.True(t, hostinfo.sentSinceCheck())
-	assert.True(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.True(t, hostinfo.out.Load())
+	assert.True(t, hostinfo.in.Load())

 	now := time.Now()
 	decision, _, _ := nc.makeTrafficDecision(hostinfo.localIndexId, now)
 	assert.Equal(t, tryRehandshake, decision)
 	assert.Equal(t, now, hostinfo.lastUsed)
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.False(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())

 	decision, _, _ = nc.makeTrafficDecision(hostinfo.localIndexId, now.Add(time.Second*5))
 	assert.Equal(t, doNothing, decision)
 	assert.Equal(t, now, hostinfo.lastUsed)
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.False(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())

 	// Do another traffic check tick, should still not be pending deletion
 	decision, _, _ = nc.makeTrafficDecision(hostinfo.localIndexId, now.Add(time.Second*10))
 	assert.Equal(t, doNothing, decision)
 	assert.Equal(t, now, hostinfo.lastUsed)
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.False(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])

@@ -358,9 +358,9 @@ func Test_NewConnectionManager_DisconnectInactive(t *testing.T) {
 	decision, _, _ = nc.makeTrafficDecision(hostinfo.localIndexId, now.Add(time.Minute*10))
 	assert.Equal(t, closeTunnel, decision)
 	assert.Equal(t, now, hostinfo.lastUsed)
-	assert.False(t, hostinfo.isPendingDeletion())
-	assert.False(t, hostinfo.sentSinceCheck())
-	assert.False(t, (hostinfo.state.Load()&stateIn != 0))
+	assert.False(t, hostinfo.pendingDeletion.Load())
+	assert.False(t, hostinfo.out.Load())
+	assert.False(t, hostinfo.in.Load())
 	assert.Contains(t, nc.hostMap.Indexes, hostinfo.localIndexId)
 	assert.Contains(t, nc.hostMap.Hosts, hostinfo.vpnAddrs[0])
 }
@@ -14,7 +14,7 @@ import (
 )

 const (
-	ReplayWindow = 8192
+	ReplayWindow = 1024

 	// RehandshakeAfterMessages rolls keys inside the AES-GCM data-volume margin (~2^-36 advantage at 64KB frames).
 	RehandshakeAfterMessages = uint64(1) << 34
@@ -26,14 +26,6 @@ const (
 // RehandshakeAfterMessages must stay below RejectAfterMessages so tunnels roll before the hard send stop.
 const _ = RejectAfterMessages - RehandshakeAfterMessages

-// sessionEpoch hands out a receiver-local ordinal to every ConnectionState at creation. The RX
-// staging sort (overlay/batch) orders packets by (epoch, message counter). A re-handshake never
-// rekeys an existing tunnel; it brings up a new hostinfo and ConnectionState with a counter space
-// starting near zero, while the old tunnel keeps decrypting until torn down. During that cutover
-// one flush batch can hold packets from both tunnels, and the epoch keeps the old tunnel's
-// packets sorted first.
-var sessionEpoch atomic.Uint64
-
 type ConnectionState struct {
 	eKey           noiseutil.CipherState
 	dKey           noiseutil.CipherState
@@ -44,8 +36,6 @@ type ConnectionState struct {
 	window         *Bits
 	decryptLock    sync.Mutex
 	writeLock      sync.Mutex
-	// epoch is this session's sessionEpoch ordinal. Immutable after creation.
-	epoch uint64
 }

 // newConnectionStateFromResult builds a fully-populated ConnectionState from a
@@ -65,7 +55,6 @@ func newConnectionStateFromResult(r *handshake.Result) (*ConnectionState, error)
 		eKey:      noiseutil.NewCipherState(r.EKey, r.Cipher),
 		dKey:      noiseutil.NewCipherState(r.DKey, r.Cipher),
 		window:    NewBits(ReplayWindow),
-		epoch:     sessionEpoch.Add(1),
 	}
 	ci.messageCounter.Add(r.MessageIndex)
 	for i := uint64(1); i <= r.MessageIndex; i++ {
@@ -96,7 +85,8 @@ func (cs *ConnectionState) Curve() cert.Curve {
 	return cs.myCert.Curve()
 }

-func (cs *ConnectionState) Decrypt(l *slog.Logger, messageCounter uint64, packet []byte, nb []byte) ([]byte, error) {
+func (cs *ConnectionState) Decrypt(l *slog.Logger, messageCounter uint64, out []byte, packet []byte, nb []byte) ([]byte, error) {
+	var err error
 	cs.decryptLock.Lock()
 	result := cs.window.Check(l, messageCounter)
 	cs.decryptLock.Unlock()
@@ -104,7 +94,7 @@ func (cs *ConnectionState) Decrypt(l *slog.Logger, messageCounter uint64, packet
 		return nil, ErrAlreadySeen
 	}

-	out, err := cs.dKey.DecryptDanger(packet[header.Len:header.Len], packet[:header.Len], packet[header.Len:], messageCounter, nb)
+	out, err = cs.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], messageCounter, nb)
 	if err != nil {
 		return nil, err
 	}
@@ -118,6 +108,7 @@ func (cs *ConnectionState) Decrypt(l *slog.Logger, messageCounter uint64, packet
 	return out, nil
 }

+// VerifyRelay verifies AEAD protected (but not encrypted) relay frames. packet must be length-checked by the caller.
 func (cs *ConnectionState) VerifyRelay(l *slog.Logger, messageCounter uint64, packet []byte, nb []byte) error {
 	cs.decryptLock.Lock()
 	result := cs.window.Check(l, messageCounter)
@@ -126,11 +117,6 @@ func (cs *ConnectionState) VerifyRelay(l *slog.Logger, messageCounter uint64, pa
 		return ErrAlreadySeen
 	}

-	// 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)-cs.dKey.Overhead()]
 	signatureValue := packet[len(packet)-cs.dKey.Overhead():]
 	_, err := cs.dKey.DecryptDanger(nil, signedPayload, signatureValue, messageCounter, nb)
@@ -144,5 +130,6 @@ func (cs *ConnectionState) VerifyRelay(l *slog.Logger, messageCounter uint64, pa
 	if !result {
 		return ErrAlreadySeen
 	}
+
 	return nil
 }
@@ -12,7 +12,6 @@ import (
 	"github.com/slackhq/nebula/handshake"
 	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/test"
-	"github.com/slackhq/nebula/udp"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -118,33 +117,7 @@ func TestSendNoMetricsDropsExhausted(t *testing.T) {

 	// The crossing send is refused: it records an exhaustion drop and never reaches connectionManager.Out.
 	assert.Equal(t, int64(1), f.messageMetrics.txExhausted.Count())
-	assert.False(t, hostinfo.sentSinceCheck())
-}
-
-// TestSendNoMetricsCloseTunnelKeepsRebindEpoch pins that a closing tunnel does not consume a rebind, a later
-// packet on a re-established tunnel still needs that edge to trigger the far-side punch.
-func TestSendNoMetricsCloseTunnelKeepsRebindEpoch(t *testing.T) {
-	initR, _ := runTestHandshake(t)
-	ci, err := newConnectionStateFromResult(initR)
-	require.NoError(t, err)
-
-	f := &Interface{
-		l:                 test.NewLogger(),
-		messageMetrics:    &MessageMetrics{txExhausted: metrics.NewCounter()},
-		writers:           []udp.Conn{udp.NoopConn{}},
-		connectionManager: &connectionManager{},
-	}
-	hostinfo := &HostInfo{vpnAddrs: []netip.Addr{netip.MustParseAddr("10.0.0.1")}, ConnectionState: ci}
-
-	// Tunnel is on epoch 0, then we rebind.
-	hostinfo.markOut(0)
-	f.rebindEpoch.Add(1)
-
-	remote := netip.MustParseAddrPort("10.0.0.2:4242")
-	f.sendNoMetrics(header.CloseTunnel, 0, ci, hostinfo, remote, []byte{}, make([]byte, 12), make([]byte, mtu), 0)
-
-	// markOut at the new epoch still reports the move, so the edge was preserved.
-	assert.True(t, hostinfo.markOut(1), "a CloseTunnel send must not consume the rebind epoch")
+	assert.False(t, hostinfo.out.Load())
 }

 func TestNewConnectionStateFromResult(t *testing.T) {
@@ -115,7 +115,7 @@ func (c *Control) Start() error {
 		c.lighthouseStart()
 	}

-	c.f.triggerShutdown = func() { go c.Stop() }
+	c.f.triggerShutdown = c.Stop

 	// Start reading packets.
 	c.f.run()
@@ -212,7 +212,7 @@ func (c *Control) RebindUDPServer() {
 	c.f.lightHouse.SendUpdate()

 	// Let the main interface know that we rebound so that underlying tunnels know to trigger punches from their remotes
-	c.f.rebindEpoch.Add(1)
+	c.f.rebindCount++
 }

 // ListHostmapHosts returns details about the actual or pending (handshaking) hostmap by vpn ip
@@ -11,8 +11,6 @@ import (

 	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/overlay/batch"
-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 	"github.com/slackhq/nebula/test"
 	"github.com/slackhq/nebula/udp"
@@ -32,9 +30,9 @@ func newFakeDevice() *fakeDevice {

 // Read blocks until Close like a real tun with no traffic, then reports EOF
 // the same way a closed device does
-func (d *fakeDevice) Read() ([]tio.Packet, error) {
+func (d *fakeDevice) Read(p []byte) (int, error) {
 	<-d.closedCh
-	return nil, io.EOF
+	return 0, io.EOF
 }

 func (d *fakeDevice) Write(p []byte) (int, error) { return len(p), nil }
@@ -51,8 +49,10 @@ func (d *fakeDevice) Activate() error                       { return nil }
 func (d *fakeDevice) Networks() []netip.Prefix              { return nil }
 func (d *fakeDevice) Name() string                          { return "fake" }
 func (d *fakeDevice) RoutesFor(netip.Addr) routing.Gateways { return nil }
-
-func (d *fakeDevice) Queues(int) ([]tio.Queue, error) { return []tio.Queue{d}, nil }
+func (d *fakeDevice) SupportsMultiqueue() bool              { return false }
+func (d *fakeDevice) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, errors.New("unsupported")
+}

 // newReadyControl hand-builds the minimum Control that Main would have
 // produced right before Start, including the construction token NewInterface
@@ -78,7 +78,7 @@ func newReadyControl(t *testing.T) (*Control, *fakeDevice, *fakeConn) {
 		inside:     dev,
 		outside:    conn,
 		writers:    []udp.Conn{conn},
-		batchers:   make([]*batch.MultiCoalescer, 1),
+		readers:    make([]io.ReadWriteCloser, 1),
 		routines:   1,
 		hostMap:    newHostMap(l),
 		lightHouse: lh,
@@ -109,8 +109,7 @@ func TestControl_StopBeforeStart(t *testing.T) {
 	require.NoError(t, c.Wait())

 	// A stopped control can never be started
-	err := c.Start()
-	require.ErrorIs(t, err, ErrAlreadyStopped)
+	require.ErrorIs(t, c.Start(), ErrAlreadyStopped)

 	// A second Stop is a harmless no-op
 	c.Stop()
@@ -144,29 +143,19 @@ type fakeConn struct {
 	rebinds int
 }

-func (c *fakeConn) Rebind() error                             { c.rebinds++; return nil }
-func (c *fakeConn) LocalAddr() (netip.AddrPort, error)        { return netip.AddrPort{}, nil }
-func (c *fakeConn) ListenOut(_ udp.EncReader, _ func()) error { return nil }
-func (c *fakeConn) WriteTo(_ []byte, _ netip.AddrPort) error  { return nil }
-func (c *fakeConn) WriteBatch(bufs [][]byte, _ []netip.AddrPort) (int, error) {
-	return len(bufs), nil
-}
-func (c *fakeConn) ReloadConfig(_ *config.C)      {}
-func (c *fakeConn) SupportsMultipleReaders() bool { return true }
-func (c *fakeConn) Close() error                  { c.closed = true; return nil }
+func (c *fakeConn) Rebind() error                            { c.rebinds++; return nil }
+func (c *fakeConn) LocalAddr() (netip.AddrPort, error)       { return netip.AddrPort{}, nil }
+func (c *fakeConn) ListenOut(_ udp.EncReader) error          { return nil }
+func (c *fakeConn) WriteTo(_ []byte, _ netip.AddrPort) error { return nil }
+func (c *fakeConn) ReloadConfig(_ *config.C)                 {}
+func (c *fakeConn) SupportsMultipleReaders() bool            { return true }
+func (c *fakeConn) Close() error                             { c.closed = true; return nil }

 type multiqueueDevice struct {
 	*fakeDevice
 }

-// Queues claims multiqueue support but fails to open the second queue,
-// exercising the activation error path.
-func (d *multiqueueDevice) Queues(n int) ([]tio.Queue, error) {
-	if n > 1 {
-		return nil, errors.New("second queue failed to open")
-	}
-	return d.fakeDevice.Queues(n)
-}
+func (d *multiqueueDevice) SupportsMultiqueue() bool { return true }

 func TestControl_StartMultiqueueFailureReleases(t *testing.T) {
 	dev := &multiqueueDevice{fakeDevice: newFakeDevice()}
@@ -177,7 +166,7 @@ func TestControl_StartMultiqueueFailureReleases(t *testing.T) {
 		inside:   dev,
 		outside:  conn,
 		writers:  []udp.Conn{conn},
-		batchers: make([]*batch.MultiCoalescer, 2),
+		readers:  make([]io.ReadWriteCloser, 2),
 		routines: 2,
 		l:        test.NewLogger(),
 	}
@@ -192,8 +181,7 @@ func TestControl_StartMultiqueueFailureReleases(t *testing.T) {
 	}

 	// The second reader fails to open, everything must be released
-	err := c.Start()
-	require.Error(t, err)
+	require.Error(t, c.Start())
 	assert.Equal(t, StateStopped, c.State())
 	assert.True(t, dev.closed, "the tun device should have been closed")
 	assert.True(t, conn.closed, "the udp socket should have been closed")
@@ -263,18 +251,15 @@ func TestControl_ConcurrentStopAndStart(t *testing.T) {
 	// panic and Wait must observe the final state
 	require.NoError(t, c.Wait())
 	assert.Equal(t, StateStopped, c.State())
-	err := c.Start()
-	require.ErrorIs(t, err, ErrAlreadyStopped)
+	require.ErrorIs(t, c.Start(), ErrAlreadyStopped)
 }

 func TestControl_StartStopLifecycle(t *testing.T) {
 	c, dev, conn := newReadyControl(t)

-	err := c.Start()
-	require.NoError(t, err)
+	require.NoError(t, c.Start())
 	assert.Equal(t, StateStarted, c.State())
-	err = c.Start()
-	require.ErrorIs(t, err, ErrAlreadyStarted)
+	require.ErrorIs(t, c.Start(), ErrAlreadyStarted)

 	// Stop must unpark the reader blocked in the device and release everything
 	c.Stop()
@@ -285,8 +270,7 @@ func TestControl_StartStopLifecycle(t *testing.T) {

 	// The reader drained off a closed device, that is not a fatal error
 	require.NoError(t, c.Wait())
-	err = c.Start()
-	require.ErrorIs(t, err, ErrAlreadyStopped)
+	require.ErrorIs(t, c.Start(), ErrAlreadyStopped)
 }

 func TestControl_RebindIsGatedByState(t *testing.T) {
@@ -296,8 +280,7 @@ func TestControl_RebindIsGatedByState(t *testing.T) {
 	c.RebindUDPServer()
 	assert.Equal(t, 0, conn.rebinds, "rebind before start must be a no-op")

-	err := c.Start()
-	require.NoError(t, err)
+	require.NoError(t, c.Start())
 	c.RebindUDPServer()
 	assert.Equal(t, 1, conn.rebinds, "rebind while started must reach the conn")

@@ -123,16 +123,6 @@ func (c *Control) SetLocalAddrsFn(fn func(*LocalAllowList) []netip.Addr) {
 	c.f.lightHouse.localAddrsFn = fn
 }

-// GetRebindEpochFor returns the rebind epoch a tunnel last sent under, so a test can tell whether a send
-// consumed the epoch edge without having to infer it from lighthouse traffic.
-func (c *Control) GetRebindEpochFor(vpnAddr netip.Addr) (uint32, bool) {
-	h := c.f.hostMap.QueryVpnAddr(vpnAddr)
-	if h == nil {
-		return 0, false
-	}
-	return h.state.Load() >> stateEpochShift, true
-}
-
 func (c *Control) KillPendingTunnel(vpnIp netip.Addr) bool {
 	hostinfo := c.f.handshakeManager.QueryVpnAddr(vpnIp)
 	if hostinfo == nil {
@@ -1,187 +0,0 @@
-// Package cpupick chooses which CPUs the tun reader threads pin to when the
-// operator has not chosen for us (tun.cpu_affinity). The stock spread —
-// allowed[i] for routine i — has two failure modes this package exists to fix:
-//
-//   - every co-located nebula starts its spread at allowed[0], so N instances
-//     on one box stack their readers onto the same cores, and allowed[0] is
-//     usually CPU 0, the core housekeeping and default IRQ affinity already
-//     favor;
-//   - on heterogeneous CPUs (ARM big.LITTLE, Intel P/E hybrids, AMD compact
-//     cores) low IDs are not necessarily fast cores, and pinning an encrypt
-//     thread to an efficiency core caps that queue's throughput.
-//
-// Default instead returns a preference-ordered pin list: the allowed set
-// filtered to performance cores (when the platform distinguishes them and
-// enough remain for every routine), confined to a single NUMA node and spread
-// across distinct physical cores when the topology permits, CPU 0's physical
-// core demoted to last resort, and the order rotated by a stable per-instance
-// key so co-located instances spread instead of stacking.
-package cpupick
-
-import (
-	"log/slog"
-
-	"github.com/slackhq/nebula/util"
-)
-
-// topology is the slice of machine layout arrange consults: the NUMA node
-// and the physical core behind each candidate CPU, plus which core CPU 0
-// lives on (zeroCore, -1 when unknown — tracked separately because CPU 0's
-// SMT sibling deserves demotion even when CPU 0 itself isn't a candidate).
-// Probed from sysfs on Linux; flatTopology stands in when the platform can't
-// say, which turns every topology rule into a no-op rather than a wrong
-// answer.
-type topology struct {
-	nodeOf   map[int]int
-	coreOf   map[int]int
-	zeroCore int
-}
-
-// flatTopology places every CPU on node 0 and on a physical core of its own.
-func flatTopology(cpus []int) topology {
-	t := topology{
-		nodeOf:   make(map[int]int, len(cpus)),
-		coreOf:   make(map[int]int, len(cpus)),
-		zeroCore: -1,
-	}
-	for i, c := range cpus {
-		t.nodeOf[c] = 0
-		t.coreOf[c] = i
-		if c == 0 {
-			t.zeroCore = i
-		}
-	}
-	return t
-}
-
-// Default computes the pin order for `routines` tun readers. key is any
-// stable per-instance value; the bound UDP port is ideal — distinct across
-// co-located instances, stable across restarts so benchmark runs stay
-// comparable. Returns nil when there is nothing useful to say (no affinity
-// support on this platform, lookup failure); callers keep their existing
-// fallback spread.
-func Default(routines int, key uint64, l *slog.Logger) []int {
-	allowed, err := util.AllowedCPUs()
-	if err != nil || len(allowed) == 0 {
-		return nil
-	}
-	perf, signal := perfCPUs(allowed)
-	cands := pickCandidates(allowed, perf, routines)
-	if len(cands) == 0 {
-		return nil
-	}
-	if len(perf) < routines {
-		signal = ""
-	}
-	cpus := arrange(cands, readTopology(cands), routines, splitmix64(key))
-	if l != nil {
-		l.Info("chose default pin CPUs for tun readers",
-			"cpus", cpus[:min(routines, len(cpus))],
-			"perfSignal", signal)
-	}
-	return cpus
-}
-
-// pickCandidates applies the enough-for-everyone guard: a perf filter that
-// leaves fewer candidates than routines is discarded — giving every reader
-// its own (possibly slow) core beats stacking two readers on a fast one.
-func pickCandidates(allowed, perf []int, routines int) []int {
-	if len(perf) < routines {
-		return allowed
-	}
-	return perf
-}
-
-// arrange turns the candidate set into the final pin order:
-//
-//  1. NUMA: when at least one node holds enough candidates for every
-//     routine, confine to one such node, chosen by the instance hash. The
-//     readers share hostmap and cipher state, so splitting one instance
-//     across nodes taxes every packet — and co-located instances that hash
-//     to different nodes stop competing entirely. When no node is big
-//     enough, span nodes rather than stack readers.
-//  2. Rotate the preferred candidates by the hash so instances spread.
-//  3. SMT: emit one thread per physical core before any of their siblings —
-//     two encrypt threads on one core split its execution units. Siblings
-//     still follow for the routines > cores case.
-//  4. CPU 0's whole physical core goes last: housekeeping and default IRQ
-//     noise on CPU 0 bleeds into its SMT sibling too. Within that tail the
-//     sibling precedes CPU 0 itself, which only catches the bleed-through.
-//
-// The rotation happens before the SMT pass so each instance's one-per-core
-// walk also starts at a different core, and CPU 0's core is excluded from
-// the rotation so no hash value can put it back at the front.
-func arrange(cands []int, topo topology, routines int, h uint64) []int {
-	byNode := map[int][]int{}
-	var nodes []int
-	for _, c := range cands {
-		n := topo.nodeOf[c]
-		if _, ok := byNode[n]; !ok {
-			nodes = append(nodes, n)
-		}
-		byNode[n] = append(byNode[n], c)
-	}
-	var eligible []int
-	for _, n := range nodes {
-		if len(byNode[n]) >= routines {
-			eligible = append(eligible, n)
-		}
-	}
-	if len(eligible) > 0 {
-		cands = byNode[eligible[int(h%uint64(len(eligible)))]]
-	}
-
-	// Split off CPU 0's core: its siblings tail the list, CPU 0 tails them.
-	preferred := make([]int, 0, len(cands))
-	var zeroTail []int
-	hasZero := false
-	for _, c := range cands {
-		switch {
-		case c == 0:
-			hasZero = true
-		case topo.zeroCore >= 0 && topo.coreOf[c] == topo.zeroCore:
-			zeroTail = append(zeroTail, c)
-		default:
-			preferred = append(preferred, c)
-		}
-	}
-	if hasZero {
-		zeroTail = append(zeroTail, 0)
-	}
-	if len(preferred) == 0 {
-		return zeroTail // CPU 0's core is all we have
-	}
-
-	// The node pick consumed the low hash bits; rotate by the high ones so
-	// the two choices stay independent.
-	off := int((h >> 32) % uint64(len(preferred)))
-	rot := make([]int, 0, len(preferred))
-	rot = append(rot, preferred[off:]...)
-	rot = append(rot, preferred[:off]...)
-
-	seenCore := make(map[int]bool, len(rot))
-	out := make([]int, 0, len(cands))
-	var siblings []int
-	for _, c := range rot {
-		g := topo.coreOf[c]
-		if seenCore[g] {
-			siblings = append(siblings, c)
-			continue
-		}
-		seenCore[g] = true
-		out = append(out, c)
-	}
-	out = append(out, siblings...)
-	out = append(out, zeroTail...)
-	return out
-}
-
-// splitmix64 decorrelates instance keys before the selection modulos: ports
-// on one box often share spacing (4242/4243, or round steps like +1000) that
-// raw key%len arithmetic would fold onto the same offset.
-func splitmix64(x uint64) uint64 {
-	x += 0x9e3779b97f4a7c15
-	x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9
-	x = (x ^ (x >> 27)) * 0x94d049bb133111eb
-	return x ^ (x >> 31)
-}
@@ -1,171 +0,0 @@
-package cpupick
-
-import (
-	"slices"
-	"testing"
-)
-
-// pairTopo builds a topology where consecutive candidate pairs are SMT
-// siblings: (cpus[0],cpus[1]) share a core, (cpus[2],cpus[3]) the next, ...
-// All CPUs land on node 0.
-func pairTopo(cpus []int) topology {
-	t := topology{
-		nodeOf:   make(map[int]int, len(cpus)),
-		coreOf:   make(map[int]int, len(cpus)),
-		zeroCore: -1,
-	}
-	for i, c := range cpus {
-		t.nodeOf[c] = 0
-		t.coreOf[c] = i / 2
-		if c == 0 {
-			t.zeroCore = i / 2
-		}
-	}
-	return t
-}
-
-func TestArrangeDemotesZeroForEveryKey(t *testing.T) {
-	candidates := []int{0, 1, 2, 3, 4, 5, 6, 7}
-	for key := range uint64(64) {
-		got := arrange(candidates, flatTopology(candidates), 4, splitmix64(key))
-		if len(got) != len(candidates) {
-			t.Fatalf("key %d: len=%d want %d", key, len(got), len(candidates))
-		}
-		if got[0] == 0 {
-			t.Errorf("key %d: CPU 0 at the front: %v", key, got)
-		}
-		if got[len(got)-1] != 0 {
-			t.Errorf("key %d: CPU 0 not demoted to last: %v", key, got)
-		}
-		sorted := slices.Clone(got)
-		slices.Sort(sorted)
-		if !slices.Equal(sorted, candidates) {
-			t.Errorf("key %d: not a permutation: %v", key, got)
-		}
-	}
-}
-
-func TestArrangeDemotesZeroSiblings(t *testing.T) {
-	// Pairs (0,1),(2,3),(4,5),(6,7): CPU 0's core — 0 and its sibling 1 —
-	// must tail the list, sibling ahead of 0 itself.
-	candidates := []int{0, 1, 2, 3, 4, 5, 6, 7}
-	for key := range uint64(64) {
-		got := arrange(candidates, pairTopo(candidates), 2, splitmix64(key))
-		n := len(got)
-		if got[n-1] != 0 || got[n-2] != 1 {
-			t.Fatalf("key %d: tail = %v, want [... 1 0]", key, got)
-		}
-	}
-}
-
-func TestArrangeZeroSiblingWithoutZero(t *testing.T) {
-	// CPU 0 excluded (cpuset) but its sibling 1 remains: the sibling still
-	// tails the list when the topology knows which core CPU 0 lives on.
-	candidates := []int{1, 2, 3, 4, 5}
-	topo := pairTopo([]int{0, 1, 2, 3, 4, 5})
-	got := arrange(candidates, topo, 2, splitmix64(7))
-	if got[len(got)-1] != 1 {
-		t.Errorf("CPU 0's sibling not demoted: %v", got)
-	}
-}
-
-func TestArrangeRotatesByKey(t *testing.T) {
-	candidates := []int{1, 2, 3, 4, 5, 6, 7, 8}
-	seen := map[int]bool{}
-	for key := range uint64(64) {
-		seen[arrange(candidates, flatTopology(candidates), 4, splitmix64(key))[0]] = true
-	}
-	// 64 hashed keys over 8 slots must hit more than one starting CPU, or
-	// co-located instances would all stack again.
-	if len(seen) < 2 {
-		t.Errorf("rotation never varied across keys: %v", seen)
-	}
-}
-
-func TestArrangeStableForSameKey(t *testing.T) {
-	candidates := []int{0, 2, 4, 6}
-	topo := flatTopology(candidates)
-	a := arrange(candidates, topo, 2, splitmix64(4242))
-	b := arrange(candidates, topo, 2, splitmix64(4242))
-	if !slices.Equal(a, b) {
-		t.Errorf("same key ordered differently: %v vs %v", a, b)
-	}
-}
-
-func TestArrangeZeroOnly(t *testing.T) {
-	if got := arrange([]int{0}, flatTopology([]int{0}), 1, splitmix64(7)); !slices.Equal(got, []int{0}) {
-		t.Errorf("sole CPU 0 must survive: %v", got)
-	}
-}
-
-func TestArrangeSMTSiblingsLast(t *testing.T) {
-	// Pairs (1,2),(3,4),(5,6),(7,8): the first four picks must cover four
-	// distinct physical cores before any sibling repeats.
-	candidates := []int{1, 2, 3, 4, 5, 6, 7, 8}
-	topo := pairTopo(candidates)
-	for key := range uint64(16) {
-		got := arrange(candidates, topo, 4, splitmix64(key))
-		seen := map[int]bool{}
-		for _, c := range got[:4] {
-			g := topo.coreOf[c]
-			if seen[g] {
-				t.Fatalf("key %d: sibling before all cores covered: %v", key, got)
-			}
-			seen[g] = true
-		}
-	}
-}
-
-func TestArrangeNUMAConfinesToOneNode(t *testing.T) {
-	// Two nodes of four; both fit routines=3, so the result must sit
-	// entirely inside one of them, and the hash must pick both across keys.
-	candidates := []int{1, 2, 3, 4, 10, 11, 12, 13}
-	topo := flatTopology(candidates)
-	for _, c := range []int{10, 11, 12, 13} {
-		topo.nodeOf[c] = 1
-	}
-	nodesSeen := map[int]bool{}
-	for key := range uint64(32) {
-		got := arrange(candidates, topo, 3, splitmix64(key))
-		if len(got) != 4 {
-			t.Fatalf("key %d: not confined to one node: %v", key, got)
-		}
-		n := topo.nodeOf[got[0]]
-		for _, c := range got {
-			if topo.nodeOf[c] != n {
-				t.Fatalf("key %d: spans nodes: %v", key, got)
-			}
-		}
-		nodesSeen[n] = true
-	}
-	if len(nodesSeen) != 2 {
-		t.Errorf("hash never spread instances across nodes: %v", nodesSeen)
-	}
-}
-
-func TestArrangeNUMASpansWhenNoNodeFits(t *testing.T) {
-	candidates := []int{1, 2, 3, 4, 10, 11, 12, 13}
-	topo := flatTopology(candidates)
-	for _, c := range []int{10, 11, 12, 13} {
-		topo.nodeOf[c] = 1
-	}
-	got := arrange(candidates, topo, 6, splitmix64(1))
-	if len(got) != len(candidates) {
-		t.Errorf("undersized nodes must span, got %v", got)
-	}
-}
-
-func TestPickCandidates(t *testing.T) {
-	allowed := []int{0, 1, 2, 3, 4, 5, 6, 7}
-	perf := []int{4, 5}
-
-	// Enough perf cores for every routine: only they are used.
-	if got := pickCandidates(allowed, perf, 2); !slices.Equal(got, perf) {
-		t.Errorf("perf filter not applied: %v", got)
-	}
-	// Perf filter too small for the routine count: discarded, everyone
-	// gets their own core from the full allowed set.
-	if got := pickCandidates(allowed, perf, 4); !slices.Equal(got, allowed) {
-		t.Errorf("undersized perf filter not discarded: %v", got)
-	}
-}
@@ -1,154 +0,0 @@
-//go:build linux
-
-package cpupick
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"strconv"
-	"strings"
-)
-
-// capacityKeepPct is the cpu_capacity admission threshold, relative to the
-// fastest allowed core. LITTLE cores are normalized to ~250-400 of the big
-// core's 1024 while mid cores sit at ~75%+, so half of max separates little
-// from the rest without splitting prime from mid on three-tier parts.
-const capacityKeepPct = 50
-
-// freqKeepPct is the cpuinfo_max_freq admission threshold. Favored-core
-// turbo skew is 2-4% and ARM mid-vs-prime ~12%, while E-cores, LITTLE
-// cores, and AMD compact cores all sit >= 20% below their siblings' max.
-const freqKeepPct = 85
-
-// perfCPUs partitions allowed into the subset that are "performance" cores,
-// consulting (in order of authority):
-//
-//  1. cpu_capacity — arch_topology's normalized per-CPU capacity, exposed on
-//     arm/arm64/riscv; the scheduler's own view of big vs LITTLE.
-//  2. /sys/devices/cpu_core/cpus — the Intel hybrid P-core PMU mask, present
-//     only on P/E parts (x86 has no cpu_capacity) and naming P cores outright.
-//  3. cpuinfo_max_freq — the cross-vendor fallback; catches AMD compact
-//     cores, which neither of the above covers.
-//
-// Returns allowed unchanged (signal "") when nothing distinguishes the
-// cores: homogeneous parts, VMs without cpufreq, sysfs unavailable.
-func perfCPUs(allowed []int) ([]int, string) {
-	return perfCPUsFrom("/sys/devices/system/cpu", "/sys/devices/cpu_core/cpus", allowed)
-}
-
-func perfCPUsFrom(cpuDir, intelCoreMask string, allowed []int) ([]int, string) {
-	if cpus, ok := byPerCPUValue(cpuDir, "cpu_capacity", allowed, capacityKeepPct); ok {
-		return cpus, "cpu_capacity"
-	}
-	if cpus, ok := byIntelCoreMask(intelCoreMask, allowed); ok {
-		return cpus, "intel_core_pmu"
-	}
-	if cpus, ok := byPerCPUValue(cpuDir, "cpufreq/cpuinfo_max_freq", allowed, freqKeepPct); ok {
-		return cpus, "max_freq"
-	}
-	return allowed, ""
-}
-
-// byPerCPUValue keeps the allowed CPUs whose per-CPU sysfs value is at least
-// keepPct percent of the maximum across allowed. Inconclusive (ok=false)
-// when any CPU is missing the file or when every value is equal.
-func byPerCPUValue(cpuDir, file string, allowed []int, keepPct int) ([]int, bool) {
-	vals := make([]int, len(allowed))
-	minV, maxV := 0, 0
-	for i, cpu := range allowed {
-		v, err := readIntFile(filepath.Join(cpuDir, fmt.Sprintf("cpu%d", cpu), file))
-		if err != nil {
-			return nil, false
-		}
-		vals[i] = v
-		if i == 0 || v < minV {
-			minV = v
-		}
-		if v > maxV {
-			maxV = v
-		}
-	}
-	if minV == maxV {
-		return nil, false // homogeneous by this signal; try the next one
-	}
-	keep := make([]int, 0, len(allowed))
-	for i, cpu := range allowed {
-		if vals[i]*100 >= maxV*keepPct {
-			keep = append(keep, cpu)
-		}
-	}
-	return keep, true
-}
-
-// byIntelCoreMask keeps the allowed CPUs named by the hybrid P-core PMU
-// mask. Inconclusive when the file is absent (non-hybrid x86, other arches)
-// or no allowed CPU is in the mask (the process was deliberately confined
-// to E-cores; nothing useful to prefer within that).
-func byIntelCoreMask(maskPath string, allowed []int) ([]int, bool) {
-	b, err := os.ReadFile(maskPath)
-	if err != nil {
-		return nil, false
-	}
-	set, err := parseCPUList(strings.TrimSpace(string(b)))
-	if err != nil || len(set) == 0 {
-		return nil, false
-	}
-	pcore := make(map[int]bool, len(set))
-	for _, c := range set {
-		pcore[c] = true
-	}
-	keep := make([]int, 0, len(allowed))
-	for _, cpu := range allowed {
-		if pcore[cpu] {
-			keep = append(keep, cpu)
-		}
-	}
-	if len(keep) == 0 {
-		return nil, false
-	}
-	return keep, true
-}
-
-// parseCPUList decodes the kernel's cpulist format ("0-7,16-23", "3") into
-// individual CPU IDs. Empty input yields an empty list.
-func parseCPUList(s string) ([]int, error) {
-	if s == "" {
-		return nil, nil
-	}
-	var out []int
-	for part := range strings.SplitSeq(s, ",") {
-		part = strings.TrimSpace(part)
-		if part == "" {
-			continue
-		}
-		lo, hi, isRange := strings.Cut(part, "-")
-		a, err := strconv.Atoi(lo)
-		if err != nil {
-			return nil, fmt.Errorf("bad cpulist entry %q: %w", part, err)
-		}
-		if !isRange {
-			out = append(out, a)
-			continue
-		}
-		b, err := strconv.Atoi(hi)
-		if err != nil {
-			return nil, fmt.Errorf("bad cpulist entry %q: %w", part, err)
-		}
-		if b < a || b-a > 8192 {
-			return nil, fmt.Errorf("bad cpulist range %q", part)
-		}
-		for v := a; v <= b; v++ {
-			out = append(out, v)
-		}
-	}
-	return out, nil
-}
-
-func readIntFile(path string) (int, error) {
-	b, err := os.ReadFile(path)
-	if err != nil {
-		return 0, err
-	}
-	return strconv.Atoi(strings.TrimSpace(string(b)))
-}
@@ -1,163 +0,0 @@
-//go:build linux
-
-package cpupick
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"slices"
-	"testing"
-)
-
-// fakeSysfs builds a cpuDir tree with the given per-CPU file values.
-// A nil map for a file means "file absent on every CPU".
-func fakeSysfs(t *testing.T, capacity, maxFreq map[int]int) string {
-	t.Helper()
-	dir := t.TempDir()
-	write := func(cpu int, rel string, v int) {
-		p := filepath.Join(dir, fmt.Sprintf("cpu%d", cpu), rel)
-		if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.WriteFile(p, fmt.Appendf(nil, "%d\n", v), 0o644); err != nil {
-			t.Fatal(err)
-		}
-	}
-	for cpu, v := range capacity {
-		write(cpu, "cpu_capacity", v)
-	}
-	for cpu, v := range maxFreq {
-		write(cpu, "cpufreq/cpuinfo_max_freq", v)
-	}
-	return dir
-}
-
-func writeCoreMask(t *testing.T, mask string) string {
-	t.Helper()
-	p := filepath.Join(t.TempDir(), "cpus")
-	if err := os.WriteFile(p, []byte(mask+"\n"), 0o644); err != nil {
-		t.Fatal(err)
-	}
-	return p
-}
-
-func TestPerfCPUsBigLittleCapacity(t *testing.T) {
-	// 4 big (1024) + 4 LITTLE (~290): capacity is authoritative on ARM.
-	dir := fakeSysfs(t, map[int]int{
-		0: 1024, 1: 1024, 2: 1024, 3: 1024,
-		4: 290, 5: 290, 6: 290, 7: 290,
-	}, nil)
-	got, signal := perfCPUsFrom(dir, filepath.Join(dir, "nope"), []int{0, 1, 2, 3, 4, 5, 6, 7})
-	if signal != "cpu_capacity" {
-		t.Fatalf("signal = %q", signal)
-	}
-	if !slices.Equal(got, []int{0, 1, 2, 3}) {
-		t.Errorf("got %v", got)
-	}
-}
-
-func TestPerfCPUsThreeTierKeepsMid(t *testing.T) {
-	// prime (1024) + mid (~780) + little (~280): 50% keeps prime+mid.
-	dir := fakeSysfs(t, map[int]int{
-		0: 280, 1: 280, 2: 280, 3: 280,
-		4: 780, 5: 780, 6: 780,
-		7: 1024,
-	}, nil)
-	got, _ := perfCPUsFrom(dir, filepath.Join(dir, "nope"), []int{0, 1, 2, 3, 4, 5, 6, 7})
-	if !slices.Equal(got, []int{4, 5, 6, 7}) {
-		t.Errorf("got %v", got)
-	}
-}
-
-func TestPerfCPUsIntelHybridMask(t *testing.T) {
-	// No cpu_capacity on x86; the P-core PMU mask decides.
-	dir := fakeSysfs(t, nil, nil)
-	mask := writeCoreMask(t, "0-7")
-	got, signal := perfCPUsFrom(dir, mask, []int{0, 1, 2, 3, 8, 9, 10, 11})
-	if signal != "intel_core_pmu" {
-		t.Fatalf("signal = %q", signal)
-	}
-	if !slices.Equal(got, []int{0, 1, 2, 3}) {
-		t.Errorf("got %v", got)
-	}
-}
-
-func TestPerfCPUsIntelMaskDisjointFallsThrough(t *testing.T) {
-	// Confined to E-cores only: the mask can't help, and equal freqs below
-	// mean nothing else distinguishes them either -> allowed unchanged.
-	dir := fakeSysfs(t, nil, map[int]int{8: 4300000, 9: 4300000})
-	mask := writeCoreMask(t, "0-7")
-	got, signal := perfCPUsFrom(dir, mask, []int{8, 9})
-	if signal != "" || !slices.Equal(got, []int{8, 9}) {
-		t.Errorf("got %v signal %q", got, signal)
-	}
-}
-
-func TestPerfCPUsMaxFreqCompactCores(t *testing.T) {
-	// AMD-style compact cores: no capacity, no Intel mask; 3.3 vs 5.7 GHz.
-	dir := fakeSysfs(t, nil, map[int]int{
-		0: 5700000, 1: 5700000, 2: 3300000, 3: 3300000,
-	})
-	got, signal := perfCPUsFrom(dir, filepath.Join(dir, "nope"), []int{0, 1, 2, 3})
-	if signal != "max_freq" {
-		t.Fatalf("signal = %q", signal)
-	}
-	if !slices.Equal(got, []int{0, 1}) {
-		t.Errorf("got %v", got)
-	}
-}
-
-func TestPerfCPUsFavoredCoreSkewKept(t *testing.T) {
-	// Turbo Boost Max favored cores run a few percent hot; they must not
-	// shrink the candidate set to one or two cores.
-	dir := fakeSysfs(t, nil, map[int]int{
-		0: 5800000, 1: 5700000, 2: 5700000, 3: 5600000,
-	})
-	got, _ := perfCPUsFrom(dir, filepath.Join(dir, "nope"), []int{0, 1, 2, 3})
-	if !slices.Equal(got, []int{0, 1, 2, 3}) {
-		t.Errorf("favored-core skew filtered CPUs: %v", got)
-	}
-}
-
-func TestPerfCPUsHomogeneousInconclusive(t *testing.T) {
-	dir := fakeSysfs(t, nil, map[int]int{0: 3000000, 1: 3000000})
-	got, signal := perfCPUsFrom(dir, filepath.Join(dir, "nope"), []int{0, 1})
-	if signal != "" || !slices.Equal(got, []int{0, 1}) {
-		t.Errorf("got %v signal %q", got, signal)
-	}
-}
-
-func TestPerfCPUsNoSysfs(t *testing.T) {
-	dir := t.TempDir()
-	got, signal := perfCPUsFrom(dir, filepath.Join(dir, "nope"), []int{0, 1, 2})
-	if signal != "" || !slices.Equal(got, []int{0, 1, 2}) {
-		t.Errorf("got %v signal %q", got, signal)
-	}
-}
-
-func TestParseCPUList(t *testing.T) {
-	cases := []struct {
-		in      string
-		want    []int
-		wantErr bool
-	}{
-		{"0-3", []int{0, 1, 2, 3}, false},
-		{"0-1,16-17", []int{0, 1, 16, 17}, false},
-		{"5", []int{5}, false},
-		{"", nil, false},
-		{"3-1", nil, true},
-		{"a-b", nil, true},
-		{"1,x", nil, true},
-	}
-	for _, c := range cases {
-		got, err := parseCPUList(c.in)
-		if (err != nil) != c.wantErr {
-			t.Errorf("%q: err=%v wantErr=%v", c.in, err, c.wantErr)
-			continue
-		}
-		if !c.wantErr && !slices.Equal(got, c.want) {
-			t.Errorf("%q: got %v want %v", c.in, got, c.want)
-		}
-	}
-}
@@ -1,10 +0,0 @@
-//go:build !linux
-
-package cpupick
-
-// perfCPUs is Linux-only sysfs walking; elsewhere report "no distinction".
-// Default already returns nil off-Linux (util.AllowedCPUs has no answer
-// there), so this exists to keep the package compiling everywhere.
-func perfCPUs(allowed []int) ([]int, string) {
-	return allowed, ""
-}
@@ -1,118 +0,0 @@
-//go:build linux
-
-package cpupick
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"strconv"
-	"strings"
-)
-
-// readTopology probes the NUMA node and physical-core layout of cpus from
-// sysfs. Anything sysfs won't say degrades toward flatTopology: an unknown
-// node becomes node 0, an unknown core becomes a core of its own — either
-// way the corresponding arrange rule becomes a no-op instead of a wrong
-// answer.
-func readTopology(cpus []int) topology {
-	return readTopologyFrom("/sys/devices/system/node", "/sys/devices/system/cpu", cpus)
-}
-
-func readTopologyFrom(nodeDir, cpuDir string, cpus []int) topology {
-	coreOf, zeroCore := coreGroups(cpuDir, cpus)
-	return topology{
-		nodeOf:   numaNodes(nodeDir, cpus),
-		coreOf:   coreOf,
-		zeroCore: zeroCore,
-	}
-}
-
-// numaNodes maps each cpu to its NUMA node via
-// /sys/devices/system/node/nodeN/cpulist. CPUs no node claims (or no node
-// dirs at all: VMs, non-NUMA kernels) land on node 0.
-func numaNodes(nodeDir string, cpus []int) map[int]int {
-	out := make(map[int]int, len(cpus))
-	for _, c := range cpus {
-		out[c] = 0
-	}
-	entries, err := os.ReadDir(nodeDir)
-	if err != nil {
-		return out
-	}
-	want := make(map[int]bool, len(cpus))
-	for _, c := range cpus {
-		want[c] = true
-	}
-	for _, e := range entries {
-		id, ok := strings.CutPrefix(e.Name(), "node")
-		if !ok {
-			continue
-		}
-		n, err := strconv.Atoi(id)
-		if err != nil {
-			continue // has_cpu, possible, ... share the prefix
-		}
-		b, err := os.ReadFile(filepath.Join(nodeDir, e.Name(), "cpulist"))
-		if err != nil {
-			continue
-		}
-		list, err := parseCPUList(strings.TrimSpace(string(b)))
-		if err != nil {
-			continue
-		}
-		for _, c := range list {
-			if want[c] {
-				out[c] = n
-			}
-		}
-	}
-	return out
-}
-
-// coreGroups maps each cpu to a dense physical-core id derived from its
-// (physical_package_id, core_id) pair — core_id alone repeats across
-// sockets. CPUs whose topology files are unreadable get a core of their own.
-// The second return is the group id of the core CPU 0 lives on, or -1 when
-// that can't be determined; CPU 0's own files are consulted even when 0 is
-// not a candidate, so its SMT siblings are recognized under cpusets that
-// exclude CPU 0 itself.
-func coreGroups(cpuDir string, cpus []int) (map[int]int, int) {
-	type pkgCore struct{ pkg, core int }
-	pairOf := func(cpu int) (pkgCore, bool) {
-		topoDir := filepath.Join(cpuDir, fmt.Sprintf("cpu%d", cpu), "topology")
-		pkg, err1 := readIntFile(filepath.Join(topoDir, "physical_package_id"))
-		core, err2 := readIntFile(filepath.Join(topoDir, "core_id"))
-		if err1 != nil || err2 != nil {
-			return pkgCore{}, false
-		}
-		return pkgCore{pkg, core}, true
-	}
-
-	ids := map[pkgCore]int{}
-	out := make(map[int]int, len(cpus))
-	next := 0
-	for _, cpu := range cpus {
-		k, ok := pairOf(cpu)
-		if !ok {
-			out[cpu] = next
-			next++
-			continue
-		}
-		id, ok := ids[k]
-		if !ok {
-			id = next
-			next++
-			ids[k] = id
-		}
-		out[cpu] = id
-	}
-
-	zeroCore := -1
-	if k, ok := pairOf(0); ok {
-		if id, ok := ids[k]; ok {
-			zeroCore = id
-		}
-	}
-	return out, zeroCore
-}
@@ -1,111 +0,0 @@
-//go:build linux
-
-package cpupick
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"testing"
-)
-
-// fakeTopoSysfs builds nodeDir/cpuDir trees. nodes maps node id -> cpulist
-// string; cores maps cpu -> (package, core) pair.
-func fakeTopoSysfs(t *testing.T, nodes map[int]string, cores map[int][2]int) (string, string) {
-	t.Helper()
-	base := t.TempDir()
-	nodeDir := filepath.Join(base, "node")
-	cpuDir := filepath.Join(base, "cpu")
-	for n, list := range nodes {
-		d := filepath.Join(nodeDir, fmt.Sprintf("node%d", n))
-		if err := os.MkdirAll(d, 0o755); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.WriteFile(filepath.Join(d, "cpulist"), []byte(list+"\n"), 0o644); err != nil {
-			t.Fatal(err)
-		}
-	}
-	for cpu, pc := range cores {
-		d := filepath.Join(cpuDir, fmt.Sprintf("cpu%d", cpu), "topology")
-		if err := os.MkdirAll(d, 0o755); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.WriteFile(filepath.Join(d, "physical_package_id"), fmt.Appendf(nil, "%d\n", pc[0]), 0o644); err != nil {
-			t.Fatal(err)
-		}
-		if err := os.WriteFile(filepath.Join(d, "core_id"), fmt.Appendf(nil, "%d\n", pc[1]), 0o644); err != nil {
-			t.Fatal(err)
-		}
-	}
-	return nodeDir, cpuDir
-}
-
-func TestReadTopology(t *testing.T) {
-	// Two nodes; SMT pairs (0,4),(1,5) on node 0 and (2,6),(3,7) on node 1.
-	// core_id repeats across packages on purpose: the pair must disambiguate.
-	nodeDir, cpuDir := fakeTopoSysfs(t,
-		map[int]string{0: "0-1,4-5", 1: "2-3,6-7"},
-		map[int][2]int{
-			0: {0, 0}, 4: {0, 0}, 1: {0, 1}, 5: {0, 1},
-			2: {1, 0}, 6: {1, 0}, 3: {1, 1}, 7: {1, 1},
-		})
-	cpus := []int{0, 1, 2, 3, 4, 5, 6, 7}
-	topo := readTopologyFrom(nodeDir, cpuDir, cpus)
-
-	for _, c := range []int{0, 1, 4, 5} {
-		if topo.nodeOf[c] != 0 {
-			t.Errorf("cpu %d on node %d, want 0", c, topo.nodeOf[c])
-		}
-	}
-	for _, c := range []int{2, 3, 6, 7} {
-		if topo.nodeOf[c] != 1 {
-			t.Errorf("cpu %d on node %d, want 1", c, topo.nodeOf[c])
-		}
-	}
-	pairs := [][2]int{{0, 4}, {1, 5}, {2, 6}, {3, 7}}
-	for _, p := range pairs {
-		if topo.coreOf[p[0]] != topo.coreOf[p[1]] {
-			t.Errorf("siblings %v not grouped: %d vs %d", p, topo.coreOf[p[0]], topo.coreOf[p[1]])
-		}
-	}
-	if topo.coreOf[0] == topo.coreOf[2] {
-		t.Error("cross-package cores with equal core_id must not merge")
-	}
-	if topo.zeroCore != topo.coreOf[0] {
-		t.Errorf("zeroCore = %d, want %d", topo.zeroCore, topo.coreOf[0])
-	}
-}
-
-func TestReadTopologyZeroCoreWithoutZeroCandidate(t *testing.T) {
-	// CPU 0 is not a candidate (cpuset excludes it) but its sibling 4 is:
-	// zeroCore must still identify their shared core.
-	nodeDir, cpuDir := fakeTopoSysfs(t,
-		map[int]string{0: "0-7"},
-		map[int][2]int{0: {0, 0}, 4: {0, 0}, 1: {0, 1}, 5: {0, 1}})
-	topo := readTopologyFrom(nodeDir, cpuDir, []int{1, 4, 5})
-	if topo.zeroCore < 0 || topo.coreOf[4] != topo.zeroCore {
-		t.Errorf("zeroCore = %d, coreOf[4] = %d; sibling of CPU 0 not identified", topo.zeroCore, topo.coreOf[4])
-	}
-	if topo.coreOf[1] == topo.zeroCore {
-		t.Error("cpu 1 wrongly grouped with CPU 0's core")
-	}
-}
-
-func TestReadTopologyMissingSysfs(t *testing.T) {
-	base := t.TempDir()
-	cpus := []int{0, 1, 2}
-	topo := readTopologyFrom(filepath.Join(base, "nope"), filepath.Join(base, "also-nope"), cpus)
-	seen := map[int]bool{}
-	for _, c := range cpus {
-		if topo.nodeOf[c] != 0 {
-			t.Errorf("cpu %d node = %d, want 0", c, topo.nodeOf[c])
-		}
-		if seen[topo.coreOf[c]] {
-			t.Errorf("cpu %d shares a fallback core group", c)
-		}
-		seen[topo.coreOf[c]] = true
-	}
-	if topo.zeroCore != -1 {
-		t.Errorf("zeroCore = %d, want -1 when unknown", topo.zeroCore)
-	}
-}
@@ -1,10 +0,0 @@
-//go:build !linux
-
-package cpupick
-
-// readTopology has no sysfs to consult off Linux; the flat stand-in makes
-// arrange's NUMA and SMT rules no-ops. Default is already nil off Linux
-// (util.AllowedCPUs has no answer there) — this keeps the package compiling.
-func readTopology(cpus []int) topology {
-	return flatTopology(cpus)
-}
@@ -4,13 +4,15 @@
 package e2e

 import (
-	"log/slog"
+	"io"
 	"net/netip"
 	"os"
 	"strings"
 	"testing"
 	"time"

+	"log/slog"
+
 	"dario.cat/mergo"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
@@ -380,7 +382,7 @@ func getAddrs(ns []netip.Prefix) []netip.Addr {
 func NewTestLogger() *slog.Logger {
 	v := os.Getenv("TEST_LOGS")
 	if v == "" {
-		return slog.New(slog.DiscardHandler)
+		return slog.New(slog.NewTextHandler(io.Discard, nil))
 	}

 	level := slog.LevelInfo
@@ -223,60 +223,3 @@ func TestRebindAdvertisesNewAddressAfterMove(t *testing.T) {
 	lhControl.Stop()
 	myControl.Stop()
 }
-
-// A relayed send records traffic but must not consume the rebind epoch. If it does, the next direct send to the
-// relay host sees the epoch already current and never requeries, so the far side is never told to punch at our
-// new address. This pins the SendVia call site, which the unit tests cannot reach.
-func TestRebindRequeriesAfterRelayedSend(t *testing.T) {
-	t.Parallel()
-	ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version2, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, []string{})
-
-	// No lighthouse on purpose: it would hand out a direct address for them and nothing would relay.
-	// Long connection manager timers so it never fires a direct test packet at the relay tunnel and bumps its
-	// epoch mid-test, which is the only other thing that touches that tunnel and would flake the assertion below.
-	myControl, myVpnIpNet, _, _ := newSimpleServer(cert.Version2, ca, caKey, "me", "10.128.0.1/24",
-		m{"relay": m{"use_relays": true}, "timers": m{"connection_alive_interval": 3600, "pending_deletion_interval": 3600}})
-	relayControl, relayVpnIpNet, relayUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "relay", "10.128.0.128/24", m{"relay": m{"am_relay": true}})
-	theirControl, theirVpnIpNet, theirUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "them", "10.128.0.2/24", m{"relay": m{"use_relays": true}})
-
-	myControl.InjectLightHouseAddr(relayVpnIpNet[0].Addr(), relayUdpAddr)
-	myControl.InjectRelays(theirVpnIpNet[0].Addr(), []netip.Addr{relayVpnIpNet[0].Addr()})
-	relayControl.InjectLightHouseAddr(theirVpnIpNet[0].Addr(), theirUdpAddr)
-
-	r := router.NewR(t, myControl, relayControl, theirControl)
-	defer r.RenderFlow()
-
-	myControl.Start()
-	relayControl.Start()
-	theirControl.Start()
-
-	myControl.InjectTunPacket(BuildTunUDPPacket(theirVpnIpNet[0].Addr(), 80, myVpnIpNet[0].Addr(), 80, []byte("establish")))
-	r.RouteForAllUntilTxTun(theirControl)
-	r.RouteFor(time.Millisecond * 500)
-
-	hi := myControl.GetHostInfoByVpnAddr(theirVpnIpNet[0].Addr(), false)
-	require.NotNil(t, hi, "expected a tunnel to them")
-	require.NotEmpty(t, hi.CurrentRelaysToMe, "them must be reachable only via the relay for this test to mean anything")
-	// sendNoMetrics only reaches SendVia when there is no direct remote, so pin that too. Without this the test
-	// keeps passing while quietly sending direct and never exercising the relay path.
-	require.False(t, hi.CurrentRemote.IsValid(), "them must have no direct remote, otherwise SendVia is never called")
-
-	before, ok := myControl.GetRebindEpochFor(relayVpnIpNet[0].Addr())
-	require.True(t, ok, "expected a tunnel to the relay")
-
-	myControl.RebindUDPServer()
-
-	// Traffic to them goes through SendVia on the relay tunnel. That must record traffic without consuming the
-	// relay tunnel's own epoch edge, which belongs to the direct path.
-	myControl.InjectTunPacket(BuildTunUDPPacket(theirVpnIpNet[0].Addr(), 80, myVpnIpNet[0].Addr(), 80, []byte("relayed")))
-	r.RouteForAllUntilTxTun(theirControl)
-
-	after, ok := myControl.GetRebindEpochFor(relayVpnIpNet[0].Addr())
-	require.True(t, ok)
-	assert.Equal(t, before, after,
-		"a relayed send consumed the relay tunnel's rebind epoch, so the next direct send will not requery")
-
-	myControl.Stop()
-	relayControl.Stop()
-	theirControl.Stop()
-}
@@ -1,136 +0,0 @@
-//go:build e2e_testing
-// +build e2e_testing
-
-package e2e
-
-import (
-	"testing"
-	"time"
-
-	"github.com/slackhq/nebula"
-	"github.com/slackhq/nebula/cert"
-	"github.com/slackhq/nebula/cert_test"
-	"github.com/slackhq/nebula/e2e/router"
-	"github.com/slackhq/nebula/udp"
-)
-
-// TestRecoveryTiming measures how long a tunnel takes to come back after the peer stops accepting our traffic,
-// which is what a laptop waking on a new network looks like from the peer's side: its NAT has no state for where
-// we are now, so everything we send disappears.
-//
-// It is a measurement, not a pass/fail assertion. Recovery is timed to the moment the peer punches back at us,
-// since that is when its NAT opens and the tunnel is usable again.
-//
-//	go test -tags e2e_testing -v -run TestRecoveryTiming ./e2e/
-func TestRecoveryTiming(t *testing.T) {
-	for _, tc := range []struct {
-		name   string
-		rebind bool
-	}{
-		{"no trigger", false},
-		{"rebind counter", true},
-	} {
-		t.Run(tc.name, func(t *testing.T) {
-			d, lost := measureRecovery(t, tc.rebind)
-			t.Logf("RESULT %-16s recovered in %-9v (%d packets lost)", tc.name, d.Round(time.Millisecond), lost)
-		})
-	}
-}
-
-// measureRecovery returns how long until the peer punched back, and how many of our packets died meanwhile. When
-// rebind is true we call RebindUDPServer once the tunnel goes dark, which is what the darwin network change
-// monitor does and what iOS has always done. When false, nothing tells nebula anything is wrong.
-func measureRecovery(t *testing.T, rebind bool) (time.Duration, int) {
-	t.Helper()
-	ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version2, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, []string{})
-
-	lhControl, lhVpnIpNet, lhUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "lh", "10.128.0.1/24", m{
-		"lighthouse": m{"am_lighthouse": true},
-	})
-
-	peerCfg := m{
-		"lighthouse": m{
-			"hosts":    []any{lhVpnIpNet[0].Addr().String()},
-			"interval": 600,
-			"local_allow_list": m{
-				"10.0.0.0/24": true,
-				"::/0":        false,
-			},
-		},
-		"static_host_map": m{
-			lhVpnIpNet[0].Addr().String(): []any{lhUdpAddr.String()},
-		},
-	}
-
-	myControl, myVpnIpNet, myUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "me", "10.128.0.2/24", peerCfg)
-	theirControl, theirVpnIpNet, theirUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "them", "10.128.0.3/24", peerCfg)
-
-	r := router.NewR(t, lhControl, myControl, theirControl)
-	defer r.RenderFlow()
-	defer func() {
-		lhControl.Stop()
-		myControl.Stop()
-		theirControl.Stop()
-	}()
-
-	lhControl.Start()
-	myControl.Start()
-	theirControl.Start()
-	r.RouteFor(time.Millisecond * 500)
-
-	myControl.InjectLightHouseAddr(theirVpnIpNet[0].Addr(), theirUdpAddr)
-	theirControl.InjectLightHouseAddr(myVpnIpNet[0].Addr(), myUdpAddr)
-
-	myControl.InjectTunPacket(BuildTunUDPPacket(theirVpnIpNet[0].Addr(), 80, myVpnIpNet[0].Addr(), 80, []byte("establish")))
-	r.RouteFor(time.Second)
-	if myControl.GetHostInfoByVpnAddr(theirVpnIpNet[0].Addr(), false) == nil {
-		t.Fatal("failed to establish the tunnel we are measuring")
-	}
-	r.RouteFor(time.Millisecond * 500)
-
-	// From here the peer's NAT has no state for us, everything we send it disappears
-	start := time.Now()
-	blackholed := 0
-	var recovered time.Duration
-
-	if rebind {
-		myControl.RebindUDPServer()
-	}
-
-	// Keep the tun busy the way someone retrying a stalled connection would
-	stop := make(chan struct{})
-	defer close(stop)
-	go func() {
-		tick := time.NewTicker(time.Millisecond * 200)
-		defer tick.Stop()
-		for {
-			select {
-			case <-stop:
-				return
-			case <-tick.C:
-				myControl.InjectTunPacket(BuildTunUDPPacket(
-					theirVpnIpNet[0].Addr(), 80, myVpnIpNet[0].Addr(), 80, []byte("retry")))
-			}
-		}
-	}()
-
-	r.RouteForAllExitFuncOrTimeout(time.Second*30, func(p *udp.Packet, c *nebula.Control) router.ExitType {
-		if c == theirControl && p.From == myControl.GetUDPAddr() {
-			blackholed++
-			return router.Drop
-		}
-
-		// The peer reaching us directly is the moment its NAT opened, whether that is a punch or a handshake
-		if c == myControl && p.From == theirUdpAddr {
-			recovered = time.Since(start)
-			return router.RouteAndExit
-		}
-
-		return router.KeepRouting
-	})
-
-	if recovered == 0 {
-		t.Fatalf("no recovery within 30s (%d packets blackholed)", blackholed)
-	}
-	return recovered, blackholed
-}
@@ -6,13 +6,11 @@ package router
 import (
 	"context"
 	"fmt"
-	"maps"
 	"net/netip"
 	"os"
 	"path/filepath"
 	"reflect"
 	"regexp"
-	"slices"
 	"sort"
 	"sync"
 	"sync/atomic"
@@ -24,6 +22,7 @@ import (
 	"github.com/slackhq/nebula"
 	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/udp"
+	"golang.org/x/exp/maps"
 )

 // outNatKey is the (from, to) pair used by outNat. Comparable struct, so it works as a map key without the
@@ -154,9 +153,6 @@ const (
 	ExitNow ExitType = 1
 	// RouteAndExit routes this packet and exits immediately afterwards
 	RouteAndExit ExitType = 2
-	// Drop discards this packet without delivering it and keeps routing. Use it to simulate a blackhole, such as
-	// a restrictive NAT refusing traffic from an address it has not seen.
-	Drop ExitType = 3
 )

 type ExitFunc func(packet *udp.Packet, receiver *nebula.Control) ExitType
@@ -167,9 +163,7 @@ type ExitFunc func(packet *udp.Packet, receiver *nebula.Control) ExitType
 func NewR(t testing.TB, controls ...*nebula.Control) *R {
 	ctx, cancel := context.WithCancel(context.Background())

-	// t.Name() contains a slash for subtests, so the flow log can land in a nested directory
-	fn := filepath.Join("mermaid", fmt.Sprintf("%s.md", t.Name()))
-	if err := os.MkdirAll(filepath.Dir(fn), 0755); err != nil {
+	if err := os.MkdirAll("mermaid", 0755); err != nil {
 		panic(err)
 	}

@@ -180,7 +174,7 @@ func NewR(t testing.TB, controls ...*nebula.Control) *R {
 		outNat:       make(map[outNatKey]netip.AddrPort),
 		flow:         []flowEntry{},
 		ignoreFlows:  []ignoreFlow{},
-		fn:           fn,
+		fn:           filepath.Join("mermaid", fmt.Sprintf("%s.md", t.Name())),
 		t:            t,
 		cancelRender: cancel,
 	}
@@ -375,7 +369,7 @@ func (r *R) RenderHostmaps(title string, controls ...*nebula.Control) {
 }

 func (r *R) renderHostmaps(title string) {
-	c := slices.AppendSeq(make([]*nebula.Control, 0, len(r.controls)), maps.Values(r.controls))
+	c := maps.Values(r.controls)
 	sort.SliceStable(c, func(i, j int) bool {
 		return c[i].GetVpnAddrs()[0].Compare(c[j].GetVpnAddrs()[0]) > 0
 	})
@@ -693,10 +687,6 @@ func (r *R) RouteExitFunc(sender *nebula.Control, whatDo ExitFunc) {
 			p.Release()
 			return

-		case Drop:
-			// Record it so the flow log shows the attempt, but never hand it to the receiver
-			r.unlockedInjectFlow(sender, receiver, p, false)
-
 		case KeepRouting:
 			fp := r.unlockedInjectFlow(sender, receiver, p, false)
 			receiver.InjectUDPPacket(p)
@@ -789,10 +779,6 @@ func (r *R) RouteForAllExitFuncOrTimeout(timeout time.Duration, whatDo ExitFunc)
 			p.Release()
 			return true

-		case Drop:
-			// Record it so the flow log shows the attempt, but never hand it to the receiver
-			r.unlockedInjectFlow(cm[x], receiver, p, false)
-
 		case KeepRouting:
 			fp := r.unlockedInjectFlow(cm[x], receiver, p, false)
 			receiver.InjectUDPPacket(p)
@@ -898,10 +884,6 @@ func (r *R) RouteForAllExitFunc(whatDo ExitFunc) {
 			p.Release()
 			return

-		case Drop:
-			// Record it so the flow log shows the attempt, but never hand it to the receiver
-			r.unlockedInjectFlow(cm[x], receiver, p, false)
-
 		case KeepRouting:
 			fp := r.unlockedInjectFlow(cm[x], receiver, p, false)
 			receiver.InjectUDPPacket(p)
@@ -131,9 +131,6 @@ listen:
  port: 4242
  # Sets the max number of packets to pull from the kernel for each syscall (under systems that support recvmmsg)
  # default is 64, does not support reload
-  # Note: on Linux with UDP GRO (kernel 5.10+), each receive slot is sized for a full 64KiB coalesced
-  # superpacket, so the receive scratch is batch * 64KiB per listening socket (~4MiB per routine at the
-  # default of 64). Lower this to trade peak per-syscall throughput for memory on constrained hosts.
  #batch: 64
  # Configure socket buffers for the udp side (outside), leave unset to use the system defaults. Values will be doubled by the kernel
  # Default is net.core.rmem_default and net.core.wmem_default (/proc/sys/net/core/rmem_default and /proc/sys/net/core/rmem_default)
@@ -172,8 +169,6 @@ listen:
  # allowing for more precise routing decisions based on the packet tags. Default is 0 meaning no mark is set.
  # This setting is reloadable.
  #so_mark: 0
-  # the udp_offloads setting controls if Nebula will attempt to enable GSO and GRO for its UDP socket(s). Linux only, not reloadable.
-  # udp_offloads: false

 # Routines is the number of thread pairs to run that consume from the tun and UDP queues.
 # Currently, this defaults to 1 which means we have 1 tun queue reader and 1
@@ -267,33 +262,6 @@ tun:
  # Default MTU for every packet, safe setting is (and the default) 1300 for internet based traffic
  mtu: 1300

-  # the use_offloads setting controls if Nebula will attempt to enable GSO and GRO for the tun device. Linux only, not reloadable.
-  #use_offloads: false
-
-  # Linux only. pin_threads pins each tun reader/encrypt OS thread to a single CPU. This keeps every goroutine's
-  # batched sends flowing through one XPS-selected NIC TX ring, so packets within a flow stay ordered on the wire
-  # instead of being sprayed across multiple TX rings and reordered. Not reloadable. Coerced to false if routines <= 1.
-  #pin_threads: true
-
-  # pin_threads_key helps the CPU-auto-selector shuffle which CPUs are chosen for pinning.
-  # Valid options are "pid" or "port". Use "port" if you want Nebula to choose the same cores every time, which is nice for benchmarking.
-  # Linux only, not reloadable.
-  #pin_threads_key: "pid"
-
-  # Linux only. cpu_affinity overrides which CPUs the tun reader threads pin to: a list of CPU IDs, one per routine
-  # (see the top-level `routines` setting). Lists shorter than `routines` are modulo-cycled across the queues; extra
-  # entries are ignored. IDs must be within the process's allowed CPU set, so this respects taskset / cgroup cpusets;
-  # a non-integer or not-allowed entry disables the override, leaving the default pin selection described below.
-  # Only meaningful while pin_threads is true. Not reloadable.
-  # When unset (or rejected), the default spread prefers performance cores on heterogeneous CPUs (ARM big.LITTLE,
-  # Intel P/E hybrids, AMD compact cores), keeps all readers on one NUMA node and on distinct physical cores when the
-  # topology allows (SMT siblings last), leaves CPU 0's physical core as a last resort, and rotates its starting
-  # point per instance (keyed by the bound UDP port) so co-located nebulas don't stack their readers onto the
-  # same cores.
-  #cpu_affinity:
-  #  - 2
-  #  - 4
-
  # Route based MTU overrides, you have known vpn ip paths that can support larger MTUs you can increase/decrease them here
  routes:
    #- mtu: 8800
@@ -21,7 +21,6 @@ import (
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/firewall"
-	"github.com/slackhq/nebula/iputil"
 )

 type FirewallInterface interface {
@@ -263,11 +262,11 @@ func (f *Firewall) AddRule(incoming bool, proto uint8, startPort int32, endPort
 	}

 	switch proto {
-	case iputil.IPProtocolTCP:
+	case firewall.ProtoTCP:
 		fp = ft.TCP
-	case iputil.IPProtocolUDP:
+	case firewall.ProtoUDP:
 		fp = ft.UDP
-	case iputil.IPProtocolICMP, iputil.IPProtocolICMPv6:
+	case firewall.ProtoICMP, firewall.ProtoICMPv6:
 		//ICMP traffic doesn't have ports, so we always coerce to "any", even if a value is provided
 		if startPort != firewall.PortAny {
 			f.l.Warn("ignoring port specification for ICMP firewall rule", "startPort", startPort)
@@ -365,13 +364,13 @@ func AddFirewallRulesFromConfig(l *slog.Logger, inbound bool, c *config.C, fw Fi
 			proto = firewall.ProtoAny
 			startPort, endPort, err = parsePort(sPort)
 		case "tcp":
-			proto = iputil.IPProtocolTCP
+			proto = firewall.ProtoTCP
 			startPort, endPort, err = parsePort(sPort)
 		case "udp":
-			proto = iputil.IPProtocolUDP
+			proto = firewall.ProtoUDP
 			startPort, endPort, err = parsePort(sPort)
 		case "icmp":
-			proto = iputil.IPProtocolICMP
+			proto = firewall.ProtoICMP
 			startPort = firewall.PortAny
 			endPort = firewall.PortAny
 			if sPort != "" {
@@ -561,9 +560,9 @@ func (f *Firewall) inConns(fp firewall.Packet, h *HostInfo, caPool *cert.CAPool,
 	}

 	switch fp.Protocol {
-	case iputil.IPProtocolTCP:
+	case firewall.ProtoTCP:
 		c.Expires = time.Now().Add(f.TCPTimeout)
-	case iputil.IPProtocolUDP:
+	case firewall.ProtoUDP:
 		c.Expires = time.Now().Add(f.UDPTimeout)
 	default:
 		c.Expires = time.Now().Add(f.DefaultTimeout)
@@ -583,9 +582,9 @@ func (f *Firewall) addConn(fp firewall.Packet, incoming bool) {
 	c := &conn{}

 	switch fp.Protocol {
-	case iputil.IPProtocolTCP:
+	case firewall.ProtoTCP:
 		timeout = f.TCPTimeout
-	case iputil.IPProtocolUDP:
+	case firewall.ProtoUDP:
 		timeout = f.UDPTimeout
 	default:
 		timeout = f.DefaultTimeout
@@ -636,15 +635,15 @@ func (ft *FirewallTable) match(p firewall.Packet, incoming bool, c *cert.CachedC
 	}

 	switch p.Protocol {
-	case iputil.IPProtocolTCP:
+	case firewall.ProtoTCP:
 		if ft.TCP.match(p, incoming, c, caPool) {
 			return true
 		}
-	case iputil.IPProtocolUDP:
+	case firewall.ProtoUDP:
 		if ft.UDP.match(p, incoming, c, caPool) {
 			return true
 		}
-	case iputil.IPProtocolICMP, iputil.IPProtocolICMPv6:
+	case firewall.ProtoICMP, firewall.ProtoICMPv6:
 		if ft.ICMP.match(p, incoming, c, caPool) {
 			return true
 		}
@@ -681,7 +680,7 @@ func (fp firewallPort) match(p firewall.Packet, incoming bool, c *cert.CachedCer
 	}

 	// this branch is here to catch traffic from FirewallTable.Any.match and FirewallTable.ICMP.match
-	if p.Protocol == iputil.IPProtocolICMP || p.Protocol == iputil.IPProtocolICMPv6 {
+	if p.Protocol == firewall.ProtoICMP || p.Protocol == firewall.ProtoICMPv6 {
 		// port numbers are re-used for connection tracking of ICMP,
 		// but we don't want to actually filter on them.
 		return fp[firewall.PortAny].match(p, c, caPool)
@@ -5,8 +5,6 @@ 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
@@ -58,8 +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)
 		}
@@ -6,7 +6,6 @@ import (
 	"strings"
 	"testing"

-	"github.com/slackhq/nebula/logging"
 	"github.com/slackhq/nebula/test"
 	"github.com/stretchr/testify/assert"
 )
@@ -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()
@@ -4,14 +4,17 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/netip"
-
-	"github.com/slackhq/nebula/iputil"
 )

 type m = map[string]any

 const (
-	ProtoAny     = 0  // When we want to handle HOPOPT (0) we can change this, if ever
+	ProtoAny    = 0 // When we want to handle HOPOPT (0) we can change this, if ever
+	ProtoTCP    = 6
+	ProtoUDP    = 17
+	ProtoICMP   = 1
+	ProtoICMPv6 = 58
+
 	PortAny      = 0  // Special value for matching `port: any`
 	PortFragment = -1 // Special value for matching `port: fragment`
 )
@@ -42,13 +45,13 @@ func (fp *Packet) Copy() *Packet {
 func (fp Packet) MarshalJSON() ([]byte, error) {
 	var proto string
 	switch fp.Protocol {
-	case iputil.IPProtocolTCP:
+	case ProtoTCP:
 		proto = "tcp"
-	case iputil.IPProtocolICMP:
+	case ProtoICMP:
 		proto = "icmp"
-	case iputil.IPProtocolICMPv6:
+	case ProtoICMPv6:
 		proto = "icmpv6"
-	case iputil.IPProtocolUDP:
+	case ProtoUDP:
 		proto = "udp"
 	default:
 		proto = fmt.Sprintf("unknown %v", fp.Protocol)
@@ -62,12 +65,3 @@ func (fp Packet) MarshalJSON() ([]byte, error) {
 		"Fragment":   fp.Fragment,
 	})
 }
-
-// ParsedPacket is a Packet plus the parse byproducts the RX path reuses
-type ParsedPacket struct {
-	Packet
-	IPHdrLen int
-	// FragAny reports any fragmentation at all: MF flag or nonzero offset for IPv4, a fragment extension header for IPv6.
-	// Distinct from Packet.Fragment, which is true only for NON-FIRST fragments
-	FragAny bool
-}
@@ -13,7 +13,6 @@ import (
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/firewall"
-	"github.com/slackhq/nebula/iputil"
 	"github.com/slackhq/nebula/test"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -73,20 +72,20 @@ func TestFirewall_AddRule(t *testing.T) {
 	ti6, err := netip.ParsePrefix("fd12::34/128")
 	require.NoError(t, err)

-	require.NoError(t, fw.AddRule(true, iputil.IPProtocolTCP, 1, 1, []string{}, "", "", "", "", ""))
+	require.NoError(t, fw.AddRule(true, firewall.ProtoTCP, 1, 1, []string{}, "", "", "", "", ""))
 	// An empty rule is any
 	assert.True(t, fw.InRules.TCP[1].Any.Any.Any)
 	assert.Empty(t, fw.InRules.TCP[1].Any.Groups)
 	assert.Empty(t, fw.InRules.TCP[1].Any.Hosts)

 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c)
-	require.NoError(t, fw.AddRule(true, iputil.IPProtocolUDP, 1, 1, []string{"g1"}, "", "", "", "", ""))
+	require.NoError(t, fw.AddRule(true, firewall.ProtoUDP, 1, 1, []string{"g1"}, "", "", "", "", ""))
 	assert.Nil(t, fw.InRules.UDP[1].Any.Any)
 	assert.Contains(t, fw.InRules.UDP[1].Any.Groups[0].Groups, "g1")
 	assert.Empty(t, fw.InRules.UDP[1].Any.Hosts)

 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c)
-	require.NoError(t, fw.AddRule(true, iputil.IPProtocolICMP, 1, 1, []string{}, "h1", "", "", "", ""))
+	require.NoError(t, fw.AddRule(true, firewall.ProtoICMP, 1, 1, []string{}, "h1", "", "", "", ""))
 	//no matter what port is given for icmp, it should end up as "any"
 	assert.Nil(t, fw.InRules.ICMP[firewall.PortAny].Any.Any)
 	assert.Empty(t, fw.InRules.ICMP[firewall.PortAny].Any.Groups)
@@ -117,11 +116,11 @@ func TestFirewall_AddRule(t *testing.T) {
 	assert.True(t, ok)

 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c)
-	require.NoError(t, fw.AddRule(true, iputil.IPProtocolUDP, 1, 1, []string{"g1"}, "", "", "", "ca-name", ""))
+	require.NoError(t, fw.AddRule(true, firewall.ProtoUDP, 1, 1, []string{"g1"}, "", "", "", "ca-name", ""))
 	assert.Contains(t, fw.InRules.UDP[1].CANames, "ca-name")

 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c)
-	require.NoError(t, fw.AddRule(true, iputil.IPProtocolUDP, 1, 1, []string{"g1"}, "", "", "", "", "ca-sha"))
+	require.NoError(t, fw.AddRule(true, firewall.ProtoUDP, 1, 1, []string{"g1"}, "", "", "", "", "ca-sha"))
 	assert.Contains(t, fw.InRules.UDP[1].CAShas, "ca-sha")

 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c)
@@ -186,7 +185,7 @@ func TestFirewall_Drop(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("1.2.3.4"),
 		LocalPort:  10,
 		RemotePort: 90,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}

@@ -264,7 +263,7 @@ func TestFirewall_DropV6(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("fd12::34"),
 		LocalPort:  10,
 		RemotePort: 90,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}

@@ -351,7 +350,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			Certificate: &dummyCert{},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolUDP}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoUDP}, true, c, cp))
 		}
 	})

@@ -361,7 +360,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			Certificate: &dummyCert{},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 1}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 1}, true, c, cp))
 		}
 	})

@@ -371,7 +370,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 		}
 		ip := netip.MustParsePrefix("9.254.254.254/32")
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 100, LocalAddr: ip.Addr()}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 100, LocalAddr: ip.Addr()}, true, c, cp))
 		}
 	})
 	b.Run("pass proto, port, fail on local CIDRv6", func(b *testing.B) {
@@ -380,7 +379,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 		}
 		ip := netip.MustParsePrefix("fd99::99/128")
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 100, LocalAddr: ip.Addr()}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 100, LocalAddr: ip.Addr()}, true, c, cp))
 		}
 	})

@@ -393,7 +392,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"nope": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 10}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 10}, true, c, cp))
 		}
 	})
 	b.Run("pass proto, port, any local CIDRv6, fail all group, name, and cidr", func(b *testing.B) {
@@ -405,7 +404,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"nope": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 10}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 10}, true, c, cp))
 		}
 	})

@@ -418,7 +417,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"nope": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 100, LocalAddr: pfix.Addr()}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 100, LocalAddr: pfix.Addr()}, true, c, cp))
 		}
 	})
 	b.Run("pass proto, port, specific local CIDRv6, fail all group, name, and cidr", func(b *testing.B) {
@@ -430,7 +429,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"nope": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.False(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 100, LocalAddr: pfix6.Addr()}, true, c, cp))
+			assert.False(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 100, LocalAddr: pfix6.Addr()}, true, c, cp))
 		}
 	})

@@ -442,7 +441,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"good-group": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.True(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 10}, true, c, cp))
+			assert.True(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 10}, true, c, cp))
 		}
 	})

@@ -454,7 +453,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"good-group": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.True(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 100, LocalAddr: pfix.Addr()}, true, c, cp))
+			assert.True(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 100, LocalAddr: pfix.Addr()}, true, c, cp))
 		}
 	})
 	b.Run("pass on group on specific local cidr6", func(b *testing.B) {
@@ -465,7 +464,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"good-group": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			assert.True(b, ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 100, LocalAddr: pfix6.Addr()}, true, c, cp))
+			assert.True(b, ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 100, LocalAddr: pfix6.Addr()}, true, c, cp))
 		}
 	})

@@ -477,7 +476,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 			InvertedGroups: map[string]struct{}{"nope": {}},
 		}
 		for n := 0; n < b.N; n++ {
-			ft.match(firewall.Packet{Protocol: iputil.IPProtocolTCP, LocalPort: 10}, true, c, cp)
+			ft.match(firewall.Packet{Protocol: firewall.ProtoTCP, LocalPort: 10}, true, c, cp)
 		}
 	})
 }
@@ -493,7 +492,7 @@ func TestFirewall_Drop2(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("1.2.3.4"),
 		LocalPort:  10,
 		RemotePort: 90,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}

@@ -551,7 +550,7 @@ func TestFirewall_Drop3(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("1.2.3.4"),
 		LocalPort:  1,
 		RemotePort: 1,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}

@@ -639,7 +638,7 @@ func TestFirewall_Drop3V6(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("fd12::34"),
 		LocalPort:  1,
 		RemotePort: 1,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}

@@ -676,7 +675,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("1.2.3.4"),
 		LocalPort:  10,
 		RemotePort: 90,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}
 	network := netip.MustParsePrefix("1.2.3.4/24")
@@ -759,13 +758,13 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 	templ := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("1.2.3.4"),
 		RemoteAddr: netip.MustParseAddr("1.2.3.4"),
-		Protocol:   iputil.IPProtocolICMP,
+		Protocol:   firewall.ProtoICMP,
 		Fragment:   false,
 	}

 	t.Run("ICMP allowed", func(t *testing.T) {
 		fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
-		require.NoError(t, fw.AddRule(true, iputil.IPProtocolICMP, 0, 0, []string{"any"}, "", "", "", "", ""))
+		require.NoError(t, fw.AddRule(true, firewall.ProtoICMP, 0, 0, []string{"any"}, "", "", "", "", ""))
 		t.Run("zero ports", func(t *testing.T) {
 			p := templ.Copy()
 			p.LocalPort = 0
@@ -911,7 +910,7 @@ func TestFirewall_DropIPSpoofing(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("192.0.2.3"),
 		LocalPort:  1,
 		RemotePort: 1,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}
 	assert.Equal(t, fw.Drop(p, true, &h1, cp, nil), ErrInvalidRemoteIP)
@@ -962,7 +961,7 @@ func TestFirewall_ConntrackSourceSpoofingAcrossPeers(t *testing.T) {
 		RemoteAddr: netip.MustParseAddr("192.0.2.2"),
 		LocalPort:  443,
 		RemotePort: 55000,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 	}

 	require.NoError(t, fw.Drop(flow, true, &victimHI, cp, nil),
@@ -1032,7 +1031,7 @@ func BenchmarkFirewallDropConntrackHit(b *testing.B) {
 		RemoteAddr: netip.MustParseAddr("192.0.2.2"),
 		LocalPort:  443,
 		RemotePort: 55000,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 	}

 	cases := []struct {
@@ -1318,28 +1317,28 @@ func TestAddFirewallRulesFromConfig(t *testing.T) {
 	mf := &mockFirewall{}
 	conf.Settings["firewall"] = map[string]any{"outbound": []any{map[string]any{"port": "1", "proto": "tcp", "host": "a"}}}
 	require.NoError(t, AddFirewallRulesFromConfig(l, false, conf, mf))
-	assert.Equal(t, addRuleCall{incoming: false, proto: iputil.IPProtocolTCP, startPort: 1, endPort: 1, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)
+	assert.Equal(t, addRuleCall{incoming: false, proto: firewall.ProtoTCP, startPort: 1, endPort: 1, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)

 	// Test adding udp rule
 	conf = config.NewC(test.NewLogger())
 	mf = &mockFirewall{}
 	conf.Settings["firewall"] = map[string]any{"outbound": []any{map[string]any{"port": "1", "proto": "udp", "host": "a"}}}
 	require.NoError(t, AddFirewallRulesFromConfig(l, false, conf, mf))
-	assert.Equal(t, addRuleCall{incoming: false, proto: iputil.IPProtocolUDP, startPort: 1, endPort: 1, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)
+	assert.Equal(t, addRuleCall{incoming: false, proto: firewall.ProtoUDP, startPort: 1, endPort: 1, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)

 	// Test adding icmp rule
 	conf = config.NewC(test.NewLogger())
 	mf = &mockFirewall{}
 	conf.Settings["firewall"] = map[string]any{"outbound": []any{map[string]any{"port": "1", "proto": "icmp", "host": "a"}}}
 	require.NoError(t, AddFirewallRulesFromConfig(l, false, conf, mf))
-	assert.Equal(t, addRuleCall{incoming: false, proto: iputil.IPProtocolICMP, startPort: firewall.PortAny, endPort: firewall.PortAny, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)
+	assert.Equal(t, addRuleCall{incoming: false, proto: firewall.ProtoICMP, startPort: firewall.PortAny, endPort: firewall.PortAny, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)

 	// Test adding icmp rule no port
 	conf = config.NewC(test.NewLogger())
 	mf = &mockFirewall{}
 	conf.Settings["firewall"] = map[string]any{"outbound": []any{map[string]any{"proto": "icmp", "host": "a"}}}
 	require.NoError(t, AddFirewallRulesFromConfig(l, false, conf, mf))
-	assert.Equal(t, addRuleCall{incoming: false, proto: iputil.IPProtocolICMP, startPort: firewall.PortAny, endPort: firewall.PortAny, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)
+	assert.Equal(t, addRuleCall{incoming: false, proto: firewall.ProtoICMP, startPort: firewall.PortAny, endPort: firewall.PortAny, groups: nil, host: "a", ip: "", localIp: ""}, mf.lastCall)

 	// Test adding any rule
 	conf = config.NewC(test.NewLogger())
@@ -1583,7 +1582,7 @@ func buildTestCase(setup testsetup, err error, theirPrefixes ...netip.Prefix) te
 		RemoteAddr: theirPrefixes[0].Addr(),
 		LocalPort:  10,
 		RemotePort: 90,
-		Protocol:   iputil.IPProtocolUDP,
+		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}
 	return testcase{
@@ -15,15 +15,16 @@ require (
 	github.com/miekg/dns v1.1.72
 	github.com/miekg/pkcs11 v1.1.2
 	github.com/nbrownus/go-metrics-prometheus v0.0.0-20210712211119-974a6260965f
-	github.com/prometheus/client_golang v1.24.1
+	github.com/prometheus/client_golang v1.23.2
 	github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
 	github.com/stefanberger/go-pkcs11uri v0.0.0-20230803200340-78284954bff6
-	github.com/stretchr/testify v1.12.0
+	github.com/stretchr/testify v1.11.1
 	github.com/vishvananda/netlink v1.3.1
 	go.uber.org/goleak v1.3.0
-	go.yaml.in/yaml/v3 v3.0.5
+	go.yaml.in/yaml/v3 v3.0.4
 	golang.org/x/crypto v0.54.0
+	golang.org/x/exp v0.0.0-20230725093048-515e97ebf090
 	golang.org/x/net v0.57.0
 	golang.org/x/sync v0.22.0
 	golang.org/x/sys v0.47.0
@@ -39,12 +40,15 @@ require (
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	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/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
-	github.com/prometheus/common v0.70.1 // indirect
-	github.com/prometheus/procfs v0.21.1 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
 	github.com/vishvananda/netns v0.0.5 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
 	golang.org/x/mod v0.36.0 // indirect
 	golang.org/x/time v0.5.0 // indirect
 	golang.org/x/tools v0.45.0 // indirect
@@ -20,6 +20,7 @@ github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XL
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+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=
@@ -67,14 +68,15 @@ github.com/kardianos/service v1.3.0 h1:/LGy+xPP2TM+GLTiCZ2di7cy0Jd/qrawlTUfqKYFd
 github.com/kardianos/service v1.3.0/go.mod h1:E4V9ufUuY82F7Ztlu1eN9VXWIQxg8NoLQlmFe0MtrXc=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
-github.com/klauspost/compress v1.19.1 h1:VsB4HPswih7mmZ8WleSFQ75c/Ui1M4trX5oAsJnhSlk=
-github.com/klauspost/compress v1.19.1/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
+github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
+github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
-github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
@@ -98,13 +100,14 @@ github.com/nbrownus/go-metrics-prometheus v0.0.0-20210712211119-974a6260965f/go.
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
 github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5FsnadC4Ky3P0J6CfImo=
 github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=
 github.com/prometheus/client_golang v1.11.0/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
-github.com/prometheus/client_golang v1.24.1 h1:JnJkREXzWxUdCuPFpIWZiPispT9xVV59uiuyR2bPlnU=
-github.com/prometheus/client_golang v1.24.1/go.mod h1:F+oSRECHg4sse5ucfYpYDeIv/hu68Zo0uoHKetWnzcE=
+github.com/prometheus/client_golang v1.23.2 h1:Je96obch5RDVy3FDMndoUsjAhG5Edi49h0RJWRi/o0o=
+github.com/prometheus/client_golang v1.23.2/go.mod h1:Tb1a6LWHB3/SPIzCoaDXI4I8UHKeFTEQ1YCr+0Gyqmg=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
@@ -113,16 +116,18 @@ github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvM
 github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
 github.com/prometheus/common v0.10.0/go.mod h1:Tlit/dnDKsSWFlCLTWaA1cyBgKHSMdTB80sz/V91rCo=
 github.com/prometheus/common v0.26.0/go.mod h1:M7rCNAaPfAosfx8veZJCuw84e35h3Cfd9VFqTh1DIvc=
-github.com/prometheus/common v0.70.1 h1:1HvjP4D5oL3t8RsPlwxA9onvvStjtIHYE5XuuwOi/PY=
-github.com/prometheus/common v0.70.1/go.mod h1:VdFUQDMZK3VLkurFUVhia6uys/0suUp86TJz5qbJRhc=
+github.com/prometheus/common v0.66.1 h1:h5E0h5/Y8niHc5DlaLlWLArTQI7tMrsfQjHV+d9ZoGs=
+github.com/prometheus/common v0.66.1/go.mod h1:gcaUsgf3KfRSwHY4dIMXLPV0K/Wg1oZ8+SbZk/HH/dA=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
 github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
-github.com/prometheus/procfs v0.21.1 h1:GljZCt+zSTS+NZq88cyQ1LjZ+RCHp3uVuabBWA5+OJI=
-github.com/prometheus/procfs v0.21.1/go.mod h1:aB55Cww9pdSJVHk0hUf0inxWyyjPogFIjmHKYgMKmtY=
+github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzMyRg=
+github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
 github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 h1:N/ElC8H3+5XpJzTSTfLsJV/mx9Q9g7kxmchpfZyxgzM=
 github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
+github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
 github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
@@ -136,8 +141,8 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.12.0 h1:K6Mr6jO9JICuend/5xzTM03ydSV3vdNRYAdPSukj8uI=
-github.com/stretchr/testify v1.12.0/go.mod h1:bOYBZb5qJ00vPzWfIqBUZPaxK8jWiXc6d3ErP4Ca9Gw=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/vishvananda/netlink v1.3.1 h1:3AEMt62VKqz90r0tmNhog0r/PpWKmrEShJU0wJW6bV0=
 github.com/vishvananda/netlink v1.3.1/go.mod h1:ARtKouGSTGchR8aMwmkzC0qiNPrrWO5JS/XMVl45+b4=
 github.com/vishvananda/netns v0.0.5 h1:DfiHV+j8bA32MFM7bfEunvT8IAqQ/NzSJHtcmW5zdEY=
@@ -146,10 +151,10 @@ github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9de
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
-go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
-go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
-go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
-go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
+go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
+go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
+go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
+go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
@@ -157,6 +162,8 @@ golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2/go.mod h1:T9bdIzuCu7OtxOm1hfPfRQxPLYneinmdGuTeoZ9dtd4=
 golang.org/x/crypto v0.54.0 h1:YLIA59K4fiNzHzjnZt2tUJQjQtUWfWbeHBqKtk3eScw=
 golang.org/x/crypto v0.54.0/go.mod h1:KWL8ny2AZdGR2cWmzeHrp2azQPGogOv+HeQaVEXC2dk=
+golang.org/x/exp v0.0.0-20230725093048-515e97ebf090 h1:Di6/M8l0O2lCLc6VVRWhgCiApHV8MnQurBnFSHsQtNY=
+golang.org/x/exp v0.0.0-20230725093048-515e97ebf090/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
@@ -807,7 +807,7 @@ func (hm *HandshakeManager) beginHandshake(via ViaSender, packet []byte, h *head
 	}

 	hm.sendHandshakeResponse(via, response, hostinfo, false)
-	hostinfo.remotes.RefreshFromHandshake(vpnAddrs, remoteCert.Certificate.Version())
+	hostinfo.remotes.RefreshFromHandshake(vpnAddrs)

 	// Don't wait for UpdateWorker
 	if f.lightHouse.IsAnyLighthouseAddr(vpnAddrs) {
@@ -987,15 +987,12 @@ func (hm *HandshakeManager) continueHandshake(via ViaSender, hh *HandshakeHostIn
 		nb := make([]byte, 12, 12)
 		out := make([]byte, mtu)
 		for _, cp := range hh.packetStore {
-			// TODO: use a SendBatch here. Each callback lands in
-			// sendNoMetrics -> WriteTo: one syscall per cached packet,
-			// where one sendmmsg could flush the whole store.
 			cp.callback(cp.messageType, cp.messageSubType, hostinfo, cp.packet, nb, out)
 		}
 		f.cachedPacketMetrics.sent.Inc(int64(len(hh.packetStore)))
 	}

-	hostinfo.remotes.RefreshFromHandshake(vpnAddrs, remoteCert.Certificate.Version())
+	hostinfo.remotes.RefreshFromHandshake(vpnAddrs)
 	f.metricHandshakes.Update(duration)

 	// Don't wait for UpdateWorker
@@ -1101,7 +1098,7 @@ 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.relay.LocalIndex, Established)
-		f.SendVia(via.relayHI, via.relay, msg, make([]byte, 12), make([]byte, mtu), false, 0)
+		f.SendVia(via.relayHI, via.relay, msg, make([]byte, 12), make([]byte, mtu), false)
 		f.l.Info("Handshake message sent", append(logFields, "relay", via.relayHI.vpnAddrs[0])...)
 	}
 }
@@ -84,7 +84,7 @@ func (mw *mockEncWriter) SendMessageToVpnAddr(_ header.MessageType, _ header.Mes
 	return
 }

-func (mw *mockEncWriter) SendVia(via *HostInfo, relay *Relay, ad, nb, out []byte, nocopy bool, q int) {
+func (mw *mockEncWriter) SendVia(_ *HostInfo, _ *Relay, _, _, _ []byte, _ bool) {
 	return
 }

@@ -190,18 +190,13 @@ func SubTypeName(t MessageType, s MessageSubType) string {
 }

 func IsValidSubType(t MessageType, s MessageSubType) bool {
-	switch t {
-	case Message:
-		return s == MessageNone || s == MessageRelay
-	case Handshake:
-		return s == HandshakeIXPSK0
-	case Test:
-		return s == TestReply || s == TestRequest
-	case Control, CloseTunnel, RecvError, LightHouse:
-		return s == 0
-	default:
-		return false
+	if n, ok := subTypeMap[t]; ok {
+		if _, ok := (*n)[s]; ok {
+			return true
+		}
 	}
+
+	return false
 }

 // NewHeader turns bytes into a header
@@ -102,57 +102,6 @@ func TestTypeMap(t *testing.T) {
 	}, subTypeMap)
 }

-// mapIsValidSubType is the pre-refactor, map-driven definition of a valid
-// subtype. IsValidSubType was reimplemented as an explicit switch; this keeps
-// the original behavior around so we can prove the switch is equivalent to it.
-func mapIsValidSubType(t MessageType, s MessageSubType) bool {
-	if n, ok := subTypeMap[t]; ok {
-		if _, ok := (*n)[s]; ok {
-			return true
-		}
-	}
-	return false
-}
-
-func TestIsValidSubType(t *testing.T) {
-	// Explicit intent table: documents exactly which subtypes are valid so the
-	// test stays meaningful even if both the switch and subTypeMap change.
-	assert.True(t, IsValidSubType(Message, MessageNone))
-	assert.True(t, IsValidSubType(Message, MessageRelay))
-	assert.False(t, IsValidSubType(Message, 2))
-
-	assert.True(t, IsValidSubType(Handshake, HandshakeIXPSK0))
-	// HandshakeXXPSK0 is defined but not a wire-valid subtype.
-	assert.False(t, IsValidSubType(Handshake, HandshakeXXPSK0))
-
-	assert.True(t, IsValidSubType(Test, TestRequest))
-	assert.True(t, IsValidSubType(Test, TestReply))
-	assert.False(t, IsValidSubType(Test, 2))
-
-	// These types only ever carry subtype 0.
-	for _, mt := range []MessageType{Control, CloseTunnel, RecvError, LightHouse} {
-		assert.True(t, IsValidSubType(mt, 0), "type %d subtype 0 should be valid", mt)
-		assert.False(t, IsValidSubType(mt, 1), "type %d subtype 1 should be invalid", mt)
-	}
-
-	// Unknown/unassigned types are never valid.
-	assert.False(t, IsValidSubType(99, 0))
-
-	// Exhaustive proof of equivalence with the original map-driven logic across
-	// the entire (type, subtype) input space.
-	for ti := 0; ti <= 0xff; ti++ {
-		for si := 0; si <= 0xff; si++ {
-			mt, mst := MessageType(ti), MessageSubType(si)
-			assert.Equalf(t, mapIsValidSubType(mt, mst), IsValidSubType(mt, mst),
-				"IsValidSubType(%d, %d) diverged from map-driven definition", ti, si)
-		}
-	}
-
-	// H method must delegate to the package function.
-	assert.True(t, (&H{Type: Test, Subtype: TestReply}).IsValidSubType())
-	assert.False(t, (&H{Type: Handshake, Subtype: HandshakeXXPSK0}).IsValidSubType())
-}
-
 func TestHeader_String(t *testing.T) {
 	assert.Equal(
 		t,
@@ -239,15 +239,11 @@ const (

 type HostInfo struct {
 	remote          atomic.Pointer[netip.AddrPort]
+	remotes         *RemoteList
+	promoteCounter  atomic.Uint32
 	ConnectionState *ConnectionState
-
-	// Traffic bits, pendingDeletion, and the rebind epoch we last sent under
-	state atomic.Uint32
-
-	promoteCounter atomic.Uint32
-	remoteIndexId  uint32
-	localIndexId   uint32
-	remotes        *RemoteList
+	remoteIndexId   uint32
+	localIndexId    uint32

 	// vpnAddrs is a list of vpn addresses assigned to this host that are within our own vpn networks
 	// The host may have other vpn addresses that are outside our
@@ -266,6 +262,11 @@ type HostInfo struct {
 	// This is used to limit lighthouse re-queries in chatty clients
 	nextLHQuery atomic.Int64

+	// lastRebindCount is the other side of Interface.rebindCount, if these values don't match then we need to ask LH
+	// for a punch from the remote end of this tunnel. The goal being to prime their conntrack for our traffic just like
+	// with a handshake
+	lastRebindCount int8
+
 	// lastHandshakeTime records the time the remote side told us about at the stage when the handshake was completed locally
 	// Stage 1 packet will contain it if I am a responder, stage 2 packet if I am an initiator
 	// This is used to avoid an attack where a handshake packet is replayed after some time
@@ -274,6 +275,9 @@ type HostInfo struct {
 	lastRoam       time.Time
 	lastRoamRemote netip.AddrPort

+	//TODO: in, out, and others might benefit from being an atomic.Int32. We could collapse connectionManager pendingDeletion, relayUsed, and in/out into this 1 thing
+	in, out, pendingDeletion atomic.Bool
+
 	// lastUsed tracks the last time ConnectionManager checked the tunnel and it was in use.
 	// This value will be behind against actual tunnel utilization in the hot path.
 	// This should only be used by the ConnectionManagers ticker routine.
@@ -539,17 +543,6 @@ func (hm *HostMap) unlockedDeleteHostInfo(hostinfo *HostInfo) bool {
 	return final
 }

-func (hm *HostMap) QueryIndexCached(index uint32, cache map[uint32]*HostInfo) *HostInfo {
-	if out, ok := cache[index]; ok {
-		return out
-	}
-	out := hm.QueryIndex(index)
-	if out != nil {
-		cache[index] = out
-	}
-	return out
-}
-
 func (hm *HostMap) QueryIndex(index uint32) *HostInfo {
 	hm.RLock()
 	if h, ok := hm.Indexes[index]; ok {
@@ -665,7 +658,7 @@ func (hm *HostMap) unlockedAddHostInfo(hostinfo *HostInfo, f *Interface) {
 	hm.Indexes[hostinfo.localIndexId] = hostinfo
 	hm.RemoteIndexes[hostinfo.remoteIndexId] = hostinfo

-	hostinfo.markOut(f.rebindEpoch.Load())
+	hostinfo.out.Store(true)
 	if f.connectionManager != nil { // f.connectionManager is only nil in some unit tests
 		f.connectionManager.trafficTimer.Add(hostinfo.localIndexId, f.connectionManager.checkInterval)
 	}
@@ -766,64 +759,6 @@ func (i *HostInfo) TryPromoteBest(preferredRanges []netip.Prefix, ifce *Interfac
 	}
 }

-// Bits within HostInfo.state, everything above stateEpochShift is the epoch
-const (
-	stateIn uint32 = 1 << iota
-	stateOut
-	statePendingDeletion
-
-	stateFlags = stateIn | stateOut | statePendingDeletion
-	// The epoch is the top 29 bits, it would take 2^29 rebinds to wrap and we will never get there
-	stateEpochShift = 3
-)
-
-// markIn records inbound traffic
-func (i *HostInfo) markIn() {
-	if i.state.Load()&stateIn == 0 {
-		i.state.Or(stateIn)
-	}
-}
-
-// markOut records a send and reports whether the epoch moved, meaning we want a punch from the far side
-func (i *HostInfo) markOut(epoch uint32) bool {
-	e := epoch << stateEpochShift
-	for {
-		old := i.state.Load()
-		if old&stateOut != 0 && old&^stateFlags == e {
-			return false
-		}
-
-		if i.state.CompareAndSwap(old, old&stateFlags|stateOut|e) {
-			return old&^stateFlags != e
-		}
-	}
-}
-
-// markOutOnly records a send without consuming the rebind epoch, for paths that cannot act on a requery
-func (i *HostInfo) markOutOnly() {
-	if i.state.Load()&stateOut == 0 {
-		i.state.Or(stateOut)
-	}
-}
-
-// takeTraffic clears both traffic bits, leaving the epoch alone, and reports what they were
-func (i *HostInfo) takeTraffic() (in bool, out bool) {
-	old := i.state.And(^(stateIn | stateOut))
-	return old&stateIn != 0, old&stateOut != 0
-}
-
-func (i *HostInfo) setPendingDeletion(v bool) {
-	if v {
-		i.state.Or(statePendingDeletion)
-	} else {
-		i.state.And(^statePendingDeletion)
-	}
-}
-
-func (i *HostInfo) isPendingDeletion() bool {
-	return i.state.Load()&statePendingDeletion != 0
-}
-
 func (i *HostInfo) GetCert() *cert.CachedCertificate {
 	if i.ConnectionState != nil {
 		return i.ConnectionState.peerCert
@@ -401,49 +401,3 @@ func TestHostMap_RelayState(t *testing.T) {
 	assert.Equal(t, []netip.Addr{}, h1.relayState.relays)

 }
-
-// sentSinceCheck reports whether anything has been sent since the connection manager last looked. Test only:
-// production reads the out bit through takeTraffic on the connection manager tick.
-func (i *HostInfo) sentSinceCheck() bool {
-	return i.state.Load()&stateOut != 0
-}
-
-func TestHostInfo_markOut(t *testing.T) {
-	h := &HostInfo{}
-	h.markOut(5) // stamped when the tunnel was added
-
-	// A tunnel already on the current epoch has nothing to report, which is what keeps a fresh tunnel from
-	// requerying on its first packet
-	assert.False(t, h.markOut(5), "an unchanged epoch should not report a move")
-	assert.True(t, h.sentSinceCheck(), "the send is still recorded as traffic")
-
-	// A rebind is observed exactly once, so we requery once per rebind
-	assert.True(t, h.markOut(6), "a bumped epoch should report a move")
-	assert.False(t, h.markOut(6), "the epoch move should only be reported once")
-
-	// Traffic and pendingDeletion live in the same word and must survive an epoch change
-	h.setPendingDeletion(true)
-	h.markIn()
-	assert.True(t, h.markOut(7))
-	assert.True(t, h.isPendingDeletion(), "pendingDeletion must survive an epoch change")
-	in, out := h.takeTraffic()
-	assert.True(t, in, "inbound traffic must survive an epoch change")
-	assert.True(t, out)
-
-	// Clearing the traffic bits leaves the epoch alone, otherwise an idle tunnel would requery forever
-	assert.False(t, h.markOut(7), "takeTraffic must not disturb the epoch")
-}
-
-// A relayed send records traffic but must leave the rebind epoch for the direct path to consume, otherwise
-// relaying to a host swallows the requery that gets the far side punching at our new address.
-func TestHostInfo_markOutOnly(t *testing.T) {
-	h := &HostInfo{}
-	h.markOut(5)
-
-	h.markOutOnly()
-	assert.True(t, h.sentSinceCheck(), "a relayed send is still outbound traffic")
-	assert.False(t, h.markOut(5), "a relayed send must not disturb the epoch")
-
-	assert.True(t, h.markOut(6), "a relayed send must not consume the epoch edge")
-	assert.False(t, h.markOut(6))
-}
@@ -2,8 +2,6 @@ package nebula

 import (
 	"context"
-	"fmt"
-	"io"
 	"log/slog"
 	"net/netip"

@@ -11,24 +9,10 @@ import (
 	"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.ParsedPacket, nb []byte, sendBatch *batch.SendBatch, 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 newPacket /
-	// firewall check covers the whole superpacket.
-	packet := pkt.Bytes
+func (f *Interface) consumeInsidePacket(packet []byte, fwPacket *firewall.Packet, nb, out []byte, q int, localCache firewall.ConntrackCache) {
 	err := newPacket(packet, false, fwPacket)
 	if err != nil {
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
@@ -53,17 +37,7 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Parse
 		// 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 {
-				// The kernel may have left the transport checksum for hardware
-				// offload to finish; nothing between here and the tun will.
-				iputil.SetTransportChecksum(seg)
-				_, werr := f.queues[q].Write(seg)
-				return werr
-			})
+			_, err := f.readers[q].Write(packet)
 			if err != nil {
 				f.l.Error("Failed to forward to tun", "error", err)
 			}
@@ -78,24 +52,12 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Parse
 		return
 	}

-	hostinfo, ready := f.getOrHandshakeConsiderRouting(&fwPacket.Packet, 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(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, 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,
@@ -109,11 +71,12 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Parse
 		return
 	}

-	dropReason := f.firewall.Drop(fwPacket.Packet, false, hostinfo, f.pki.GetCAPool(), localCache)
+	dropReason := f.firewall.Drop(*fwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason == nil {
-		f.sendInsideMessage(hostinfo, pkt, nb, sendBatch)
+		f.sendNoMetrics(header.Message, 0, hostinfo.ConnectionState, hostinfo, netip.AddrPort{}, packet, nb, out, q)
+
 	} else {
-		f.rejectInside(packet, rejectBuf, q)
+		f.rejectInside(packet, out, q)
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			hostinfo.logger(f.l).Debug("dropping outbound packet",
 				"fwPacket", fwPacket,
@@ -123,122 +86,6 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Parse
 	}
 }

-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)
-
-	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.GetRemote(),
-			"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.SendBatch) {
-	ci := hostinfo.ConnectionState
-	if ci.eKey == nil {
-		return
-	}
-
-	// One traffic-out mark covers every segment of the superpacket; doing it
-	// per segment in sendInsideEncrypt paid an atomic store up to ~45 extra
-	// times per TSO packet, inside writeLock under boring crypto.
-	//
-	// We rebound since this tunnel last sent, ask the lighthouse to get the far side punching at us again
-	if f.connectionManager.Out(hostinfo) {
-		f.lightHouse.QueryServer(hostinfo.vpnAddrs[0])
-		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("Lighthouse update triggered for punch due to rebind epoch",
-				"vpnAddrs", hostinfo.vpnAddrs,
-			)
-		}
-	}
-
-	remote := hostinfo.GetRemote()
-	if !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
-			}
-
-			sendBatch.Commit(toSend, relayHostInfo.GetRemote())
-			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
-		}
-
-		sendBatch.Commit(out, remote)
-		return nil
-	})
-	if err != nil {
-		hostinfo.logger(f.l).Error("Failed to segment superpacket for send", "error", err)
-	}
-}
-
 func (f *Interface) rejectInside(packet []byte, out []byte, q int) {
 	if !f.firewall.OutboundSendReject {
 		return
@@ -249,36 +96,33 @@ func (f *Interface) rejectInside(packet []byte, out []byte, q int) {
 		return
 	}

-	_, err := f.queues[q].Write(out)
+	_, err := f.readers[q].Write(out)
 	if err != nil {
 		f.l.Error("Failed to write to tun", "error", err)
 	}
 }

-func (f *Interface) rejectOutside(packet []byte, ci *ConnectionState, hostinfo *HostInfo, nb, rejectBuf []byte, q int) {
+func (f *Interface) rejectOutside(packet []byte, ci *ConnectionState, hostinfo *HostInfo, nb, out []byte, q int) {
 	if !f.firewall.InboundSendReject {
 		return
 	}

-	// split rejectBuf to make sure we have room to write the plaintext rejection, then encrypt it, without trampling anything
-	// we can't re-use packet, if we need to send an icmp reject, it won't be long enough.
-	half := len(rejectBuf) / 2
-	encryptBuf := rejectBuf[0:0:half] //the first half of rejectBuf's capacity, len set to 0
-	buildBuf := rejectBuf[half:]
-
-	out := iputil.CreateRejectPacket(packet, buildBuf)
+	out = iputil.CreateRejectPacket(packet, out)
 	if len(out) == 0 {
 		return
 	}

 	if len(out) > iputil.MaxRejectPacketSize {
 		if f.l.Enabled(context.Background(), slog.LevelInfo) {
-			f.l.Info("rejectOutside: packet too big, not sending", "packet", packet, "outPacket", out)
+			f.l.Info("rejectOutside: packet too big, not sending",
+				"packet", packet,
+				"outPacket", out,
+			)
 		}
 		return
 	}

-	f.sendNoMetrics(header.Message, 0, ci, hostinfo, netip.AddrPort{}, out, nb, encryptBuf, q)
+	f.sendNoMetrics(header.Message, 0, ci, hostinfo, netip.AddrPort{}, out, nb, packet, 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
@@ -372,7 +216,7 @@ func (f *Interface) getOrHandshakeConsiderRouting(fwPacket *firewall.Packet, cac
 }

 func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p, nb, out []byte) {
-	fp := &firewall.ParsedPacket{}
+	fp := &firewall.Packet{}
 	err := newPacket(p, false, fp)
 	if err != nil {
 		f.l.Warn("error while parsing outgoing packet for firewall check", "error", err)
@@ -380,7 +224,7 @@ func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubTyp
 	}

 	// check if packet is in outbound fw rules
-	dropReason := f.firewall.Drop(fp.Packet, 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",
@@ -439,13 +283,21 @@ func (f *Interface) dropExhausted(hostinfo *HostInfo, c uint64, msg string) {
 	}
 }

-func (f *Interface) prepareSendVia(via *HostInfo,
+// 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,
-) ([]byte, error) {
+) {
 	if noiseutil.EncryptLockNeeded {
 		// NOTE: for goboring AESGCMTLS we need to lock because of the nonce check
 		via.ConnectionState.writeLock.Lock()
@@ -456,11 +308,11 @@ func (f *Interface) prepareSendVia(via *HostInfo,
 			via.ConnectionState.writeLock.Unlock()
 		}
 		f.dropExhausted(via, c, "Dropping outbound relay packets, tunnel message counter is exhausted")
-		return nil, fmt.Errorf("tunnel message counter is exhausted")
+		return
 	}

 	out = header.Encode(out, header.Version, header.Message, header.MessageRelay, relay.RemoteIndex, c)
-	f.connectionManager.OutNoRebind(via)
+	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.
@@ -474,7 +326,7 @@ func (f *Interface) prepareSendVia(via *HostInfo,
 			"headerLen", len(out),
 			"cipherOverhead", via.ConnectionState.eKey.Overhead(),
 		)
-		return nil, io.ErrShortBuffer
+		return
 	}

 	// The header bytes are written to the 'out' slice; Grow the slice to hold the header and associated data payload.
@@ -494,31 +346,13 @@ func (f *Interface) prepareSendVia(via *HostInfo,
 	}
 	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
-}
-
-// 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, q int) {
-	toSend, err := f.prepareSendVia(via, relay, ad, nb, out, nocopy)
-	if err != nil {
-		// already logged by prepareSendVia
 		return
 	}
-
-	err = f.writers[q].WriteTo(toSend, via.GetRemote())
+	err = f.writers[0].WriteTo(out, via.GetRemote())
 	if err != nil {
 		via.logger(f.l).Info("Failed to WriteTo in sendVia", "error", err)
 	}
+	f.connectionManager.RelayUsed(relay.LocalIndex)
 }

 func (f *Interface) sendNoMetrics(t header.MessageType, st header.MessageSubType, ci *ConnectionState, hostinfo *HostInfo, remote netip.AddrPort, p, nb, out []byte, q int) {
@@ -553,13 +387,17 @@ func (f *Interface) sendNoMetrics(t header.MessageType, st header.MessageSubType

 	//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)
-	// A closing tunnel is torn down right after this, so skip the connection manager entirely: no point recording
-	// traffic or asking the lighthouse for a punch. Otherwise, if we rebound since this tunnel last sent, ask the
-	// lighthouse to get the far side punching at us again.
-	if t != header.CloseTunnel && f.connectionManager.Out(hostinfo) {
+	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
+	// all our addrs and enable a faster roaming.
+	if t != header.CloseTunnel && 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) {
-			f.l.Debug("Lighthouse update triggered for punch due to rebind epoch",
+			f.l.Debug("Lighthouse update triggered for punch due to rebind counter",
 				"vpnAddrs", hostinfo.vpnAddrs,
 			)
 		}
@@ -607,7 +445,7 @@ func (f *Interface) sendNoMetrics(t header.MessageType, st header.MessageSubType
 				)
 				continue
 			}
-			f.SendVia(relayHostInfo, relay, out, nb, fullOut[:header.Len+len(out)], true, q)
+			f.SendVia(relayHostInfo, relay, out, nb, fullOut[:header.Len+len(out)], true)
 			break
 		}
 	}
@@ -1,265 +0,0 @@
-package nebula
-
-import (
-	"encoding/binary"
-	"io"
-	"net/netip"
-	"testing"
-
-	"github.com/gaissmai/bart"
-	"github.com/slackhq/nebula/firewall"
-	"github.com/slackhq/nebula/iputil"
-	"github.com/slackhq/nebula/overlay/tio"
-	"github.com/slackhq/nebula/test"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-const (
-	ipv4HeaderLen = 20
-	ipv6HeaderLen = 40
-)
-
-// capturingTun is a tio.Queue that records what is written to it. A queue that
-// discards writes is indistinguishable from a packet that was never forwarded.
-type capturingTun struct {
-	writes [][]byte
-}
-
-func (c *capturingTun) Read() ([]tio.Packet, error) { return nil, io.EOF }
-func (c *capturingTun) Close() error                { return nil }
-
-func (c *capturingTun) Write(b []byte) (int, error) {
-	c.writes = append(c.writes, append([]byte(nil), b...))
-	return len(b), nil
-}
-
-func newSelfForwardInterface(myAddrs ...netip.Addr) (*Interface, *capturingTun) {
-	vpnAddrs := &bart.Lite{}
-	for _, a := range myAddrs {
-		vpnAddrs.Insert(netip.PrefixFrom(a, a.BitLen()))
-	}
-
-	tun := &capturingTun{}
-	return &Interface{
-		l:                     test.NewLogger(),
-		myVpnAddrsTable:       vpnAddrs,
-		myBroadcastAddrsTable: &bart.Lite{},
-		queues:                []tio.Queue{tun},
-	}, tun
-}
-
-func consumeInside(f *Interface, packet []byte) {
-	f.consumeInsidePacket(tio.Packet{Bytes: packet}, &firewall.ParsedPacket{}, make([]byte, 12), nil, make([]byte, mtu), 0, nil)
-}
-
-// l4Proto describes one upper-layer header for these tests: its IP next-header
-// value, where its checksum field sits within the header, and how to build a
-// minimal instance of it.
-type l4Proto struct {
-	name    string
-	nextHdr uint8
-	cksumAt int
-	build   func() []byte
-}
-
-var (
-	tcpSyn = l4Proto{"tcp", iputil.IPProtocolTCP, 16, func() []byte {
-		h := make([]byte, 20)
-		binary.BigEndian.PutUint16(h[0:2], 49152)
-		binary.BigEndian.PutUint16(h[2:4], 443)
-		binary.BigEndian.PutUint32(h[4:8], 0x11223344) // sequence
-		h[12] = 5 << 4                                 // data offset, no options
-		h[13] = 0x02                                   // SYN
-		binary.BigEndian.PutUint16(h[14:16], 65535)    // window
-		return h
-	}}
-
-	udpDatagram = l4Proto{"udp", iputil.IPProtocolUDP, 6, func() []byte {
-		h := make([]byte, 8+4)
-		binary.BigEndian.PutUint16(h[0:2], 49152)
-		binary.BigEndian.PutUint16(h[2:4], 53)
-		binary.BigEndian.PutUint16(h[4:6], uint16(len(h)))
-		copy(h[8:], "ping")
-		return h
-	}}
-
-	icmpEcho   = l4Proto{"icmp", iputil.IPProtocolICMP, 2, func() []byte { return echoRequest(8) }}
-	icmpv6Echo = l4Proto{"icmpv6", iputil.IPProtocolICMPv6, 2, func() []byte { return echoRequest(128) }}
-)
-
-// echoRequest builds an echo request body. The type differs between ICMP and
-// ICMPv6, the rest of the header does not.
-func echoRequest(typ uint8) []byte {
-	h := make([]byte, 8)
-	h[0] = typ
-	binary.BigEndian.PutUint16(h[4:6], 0xbeef) // identifier
-	binary.BigEndian.PutUint16(h[6:8], 1)      // sequence
-	return h
-}
-
-func buildIPv6(src, dst netip.Addr, p l4Proto) []byte {
-	l4 := p.build()
-	pkt := make([]byte, ipv6HeaderLen+len(l4))
-	pkt[0] = 0x60
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(len(l4)))
-	pkt[6] = p.nextHdr
-	pkt[7] = 64
-	copy(pkt[8:24], src.AsSlice())
-	copy(pkt[24:40], dst.AsSlice())
-	copy(pkt[ipv6HeaderLen:], l4)
-	if l4 := pkt[ipv6HeaderLen:]; p.nextHdr == iputil.IPProtocolTCP || p.nextHdr == iputil.IPProtocolUDP {
-		sum := ipv6PseudoheaderSum(src, dst, uint32(p.nextHdr), uint32(len(l4)))
-		binary.BigEndian.PutUint16(l4[p.cksumAt:], ^fold(sumBytes(l4, sum)))
-	}
-	return pkt
-}
-
-func buildIPv4(src, dst netip.Addr, p l4Proto) []byte {
-	l4 := p.build()
-	pkt := make([]byte, ipv4HeaderLen+len(l4))
-	pkt[0] = 0x45
-	binary.BigEndian.PutUint16(pkt[2:4], uint16(len(pkt)))
-	pkt[8] = 64
-	pkt[9] = p.nextHdr
-	copy(pkt[12:16], src.AsSlice())
-	copy(pkt[16:20], dst.AsSlice())
-	copy(pkt[ipv4HeaderLen:], l4)
-	if l4 := pkt[ipv4HeaderLen:]; p.nextHdr == iputil.IPProtocolTCP || p.nextHdr == iputil.IPProtocolUDP {
-		sum := sumBytes(pkt[12:20], uint32(p.nextHdr)+uint32(len(l4)))
-		binary.BigEndian.PutUint16(l4[p.cksumAt:], ^fold(sumBytes(l4, sum)))
-	}
-	return pkt
-}
-
-// ipv6PseudoheaderSum is the RFC 2460 section 8.1 pseudo-header sum: source,
-// destination, a 32 bit upper-layer packet length and a 32 bit zero-padded next
-// header. Kept local to the test so these assertions do not check nebula's
-// checksum code against itself.
-func ipv6PseudoheaderSum(src, dst netip.Addr, nextHeader, length uint32) uint32 {
-	var csum uint32
-	s, d := src.AsSlice(), dst.AsSlice()
-	for i := 0; i < 16; i += 2 {
-		csum += uint32(s[i])<<8 | uint32(s[i+1])
-		csum += uint32(d[i])<<8 | uint32(d[i+1])
-	}
-	return csum + length + nextHeader
-}
-
-func sumBytes(b []byte, csum uint32) uint32 {
-	for i := 0; i+1 < len(b); i += 2 {
-		csum += uint32(b[i])<<8 | uint32(b[i+1])
-	}
-	if len(b)%2 == 1 {
-		csum += uint32(b[len(b)-1]) << 8
-	}
-	return csum
-}
-
-func fold(csum uint32) uint16 {
-	for csum > 0xffff {
-		csum = (csum >> 16) + (csum & 0xffff)
-	}
-	return uint16(csum)
-}
-
-// l4ChecksumValid6 verifies an IPv6 upper-layer checksum the way a receiver
-// does: the pseudo-header plus the whole upper-layer segment, checksum field
-// included, folds to 0xffff. The next header field is the upper-layer protocol
-// only while there are no extension headers, which is all this file builds.
-func l4ChecksumValid6(pkt []byte) bool {
-	src, _ := netip.AddrFromSlice(pkt[8:24])
-	dst, _ := netip.AddrFromSlice(pkt[24:40])
-	l4 := pkt[ipv6HeaderLen:]
-	return fold(sumBytes(l4, ipv6PseudoheaderSum(src, dst, uint32(pkt[6]), uint32(len(l4))))) == 0xffff
-}
-
-// l4ChecksumValid4 is the IPv4 counterpart: the RFC 793/768 pseudo-header is
-// source, destination, a zero byte, the protocol and the upper-layer length.
-func l4ChecksumValid4(pkt []byte) bool {
-	ihl := int(pkt[0]&0x0f) << 2
-	l4 := pkt[ihl:]
-	return fold(sumBytes(l4, sumBytes(pkt[12:20], uint32(pkt[9])+uint32(len(l4))))) == 0xffff
-}
-
-// TestConsumeInsidePacketSelfTraffic covers the self-addressed branch of
-// consumeInsidePacket, taken where immediatelyForwardToSelf is set (see
-// inside_bsd.go): the packet goes straight back to the tun, ahead of the
-// firewall and the handshake.
-func TestConsumeInsidePacketSelfTraffic(t *testing.T) {
-	v4 := netip.MustParseAddr("100.100.1.42")
-	v6 := netip.MustParseAddr("fd00::42")
-
-	tests := []struct {
-		name string
-		addr netip.Addr
-		pkt  []byte
-	}{
-		{"ipv4/tcp", v4, buildIPv4(v4, v4, tcpSyn)},
-		{"ipv4/udp", v4, buildIPv4(v4, v4, udpDatagram)},
-		{"ipv4/icmp", v4, buildIPv4(v4, v4, icmpEcho)},
-		{"ipv6/tcp", v6, buildIPv6(v6, v6, tcpSyn)},
-		{"ipv6/udp", v6, buildIPv6(v6, v6, udpDatagram)},
-		{"ipv6/icmpv6", v6, buildIPv6(v6, v6, icmpv6Echo)},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			f, tun := newSelfForwardInterface(tt.addr)
-			// consumeInsidePacket writes through the slice it is handed, so a
-			// packet that arrived with a valid checksum must come back out of
-			// bytes taken before the call, unchanged.
-			want := append([]byte(nil), tt.pkt...)
-			consumeInside(f, tt.pkt)
-
-			if immediatelyForwardToSelf {
-				require.Len(t, tun.writes, 1)
-				assert.Equal(t, want, tun.writes[0])
-			} else {
-				assert.Empty(t, tun.writes, "self traffic reaches the tun over loopback here and must be dropped")
-			}
-		})
-	}
-}
-
-// TestConsumeInsidePacketSelfTrafficChecksum shows that the self-forward
-// returns the bytes it was handed, so a packet that arrived with a wrong
-// upper-layer checksum is written back with that same wrong checksum and the
-// kernel drops it on re-entry.
-//
-// This is how a macOS host loses TCP and UDP to its own IPv6 overlay address:
-// the kernel writes only the pseudo-header sum into the checksum field and
-// defers completion to hardware offload, state that does not survive the
-// crossing into userspace. Which kernels do this, for which protocols and IP
-// versions, is a property of the kernel and belongs to a test against a live
-// one; here the checksum is simply wrong, and the forward must make it right.
-func TestConsumeInsidePacketSelfTrafficChecksum(t *testing.T) {
-	if !immediatelyForwardToSelf {
-		t.Skip("self traffic never reaches the tun on this platform")
-	}
-	versions := []struct {
-		name  string
-		addr  netip.Addr
-		build func(src, dst netip.Addr, p l4Proto) []byte
-		l4At  int
-		valid func(pkt []byte) bool
-	}{
-		{"v4", netip.MustParseAddr("100.100.1.42"), buildIPv4, ipv4HeaderLen, l4ChecksumValid4},
-		{"v6", netip.MustParseAddr("fd00::42"), buildIPv6, ipv6HeaderLen, l4ChecksumValid6},
-	}
-	for _, v := range versions {
-		for _, p := range []l4Proto{tcpSyn, udpDatagram} {
-			t.Run(v.name+"/"+p.name, func(t *testing.T) {
-				pkt := v.build(v.addr, v.addr, p)
-				binary.BigEndian.PutUint16(pkt[v.l4At+p.cksumAt:], 0x1234)
-				require.False(t, v.valid(pkt), "the packet under test must start with a wrong checksum")
-				f, tun := newSelfForwardInterface(v.addr)
-				consumeInside(f, pkt)
-				require.Len(t, tun.writes, 1)
-				assert.True(t, v.valid(tun.writes[0]),
-					"a forwarded %s packet must carry a valid checksum, got 0x%04x",
-					p.name, binary.BigEndian.Uint16(tun.writes[0][v.l4At+p.cksumAt:]))
-			})
-		}
-	}
-}
@@ -2,12 +2,11 @@ package nebula

 import (
 	"context"
-	"crypto/fips140"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/netip"
-	"runtime"
 	"slices"
 	"sync"
 	"sync/atomic"
@@ -15,15 +14,12 @@ import (

 	"github.com/gaissmai/bart"
 	"github.com/rcrowley/go-metrics"
-	"github.com/slackhq/nebula/util"

 	"github.com/slackhq/nebula/cert"
 	"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"
 )

@@ -53,19 +49,7 @@ 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. Only consulted when PinThreads is true.
-	CpuAffinity []int
-	// PinThreads controls whether each TUN reader OS thread is pinned to a
-	// single CPU (via tun.pin_threads, default true). Pinning keeps each
-	// goroutine's sendmmsg on one XPS-selected NIC TX ring so per-flow
-	// packets stay ordered on the wire.
-	PinThreads bool
-
-	l *slog.Logger
+	l                     *slog.Logger
 }

 type Interface struct {
@@ -89,16 +73,7 @@ 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-(allowed CPU) behavior.
-	// Only consulted when pinThreads is true.
-	cpuAffinity []int
-	// pinThreads controls whether listenIn pins each TUN reader OS thread to
-	// a CPU at all (tun.pin_threads, default true). When false, threads are
-	// left free to migrate as on stock nebula.
-	pinThreads   bool
-	relayManager *relayManager
+	relayManager          *relayManager

 	tryPromoteEvery atomic.Uint32
 	reQueryEvery    atomic.Uint32
@@ -107,22 +82,16 @@ type Interface struct {
 	sendRecvErrorConfig   recvErrorConfig
 	acceptRecvErrorConfig recvErrorConfig

-	// Bumped on every udp rebind, tunnels compare it to decide they need a punch from the far side
-	rebindEpoch atomic.Uint32
+	// rebindCount is used to decide if an active tunnel should trigger a punch notification through a lighthouse
+	rebindCount int8
 	version     string

 	conntrackCacheTimeout time.Duration

 	ctx     context.Context
 	writers []udp.Conn
-	queues  []tio.Queue
-	// batchers is one per tun queue, wrapping queues[i]. readOutsidePackets
-	// commits plaintext into the batcher; the plaintext is decrypted
-	// in place inside the UDP receive buffers, so listenOut must call Flush
-	// at the end of each UDP recvmmsg batch, before those buffers are
-	// reused (every udp.Conn ListenOut guarantees that ordering).
-	batchers []*batch.MultiCoalescer
-	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)
@@ -133,13 +102,18 @@ type Interface struct {
 	metricHandshakes    metrics.Histogram
 	messageMetrics      *MessageMetrics
 	cachedPacketMetrics *cachedPacketMetrics
-	metricTxDropped     metrics.Counter

 	l *slog.Logger
 }

 type EncWriter interface {
-	SendVia(via *HostInfo, relay *Relay, ad, nb, out []byte, nocopy bool, q int)
+	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)
 	Handshake(vpnAddr netip.Addr)
@@ -198,10 +172,6 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		return nil, errors.New("no connection manager")
 	}

-	if c.routines <= 1 {
-		c.PinThreads = false //pinning is not useful unless there's more than one tun reader
-	}
-
 	cs := c.pki.getCertState()
 	ifce := &Interface{
 		ctx:                   ctx,
@@ -219,7 +189,7 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		routines:              c.routines,
 		version:               c.version,
 		writers:               make([]udp.Conn, c.routines),
-		batchers:              make([]*batch.MultiCoalescer, c.routines),
+		readers:               make([]io.ReadWriteCloser, c.routines),
 		myVpnNetworks:         cs.myVpnNetworks,
 		myVpnNetworksTable:    cs.myVpnNetworksTable,
 		myVpnAddrs:            cs.myVpnAddrs,
@@ -228,11 +198,8 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		relayManager:          c.relayManager,
 		connectionManager:     c.connectionManager,
 		conntrackCacheTimeout: c.ConntrackCacheTimeout,
-		cpuAffinity:           c.CpuAffinity,
-		pinThreads:            c.PinThreads,

 		metricHandshakes: metrics.GetOrRegisterHistogram("handshakes", nil, metrics.NewExpDecaySample(1028, 0.015)),
-		metricTxDropped:  metrics.GetOrRegisterCounter("udp.tx.dropped", nil),
 		messageMetrics:   c.MessageMetrics,
 		cachedPacketMetrics: &cachedPacketMetrics{
 			sent:    metrics.GetOrRegisterCounter("hostinfo.cached_packets.sent", nil),
@@ -271,41 +238,27 @@ func (f *Interface) activate() error {
 		"build", f.version,
 		"udpAddr", addr,
 		"boringcrypto", boringEnabled(),
-		"fips140Version", fips140.Version(),
-		"fips140Enabled", fips140.Enabled(),
-		"fips140Enforced", fips140.Enforced(),
 	)

-	if f.routines > 1 && !f.outside.SupportsMultipleReaders() {
-		f.routines = 1
-		f.l.Warn("multiple udp readers are not supported on this platform, falling back to a single routine")
+	if f.routines > 1 {
+		if !f.inside.SupportsMultiqueue() || !f.outside.SupportsMultipleReaders() {
+			f.routines = 1
+			f.l.Warn("routines is not supported on this platform, falling back to a single routine")
+		}
 	}

-	// Prepare the tun queues. A device that can't open that many hands back
-	// fewer (a single queue on platforms without multiqueue support) and we
-	// size the reader routines to what we actually got.
-	queues, err := f.inside.Queues(f.routines)
-	if err != nil {
-		return err
-	}
-	if len(queues) < f.routines {
-		// TODO: this clamp is only safe because it is unreachable when the
-		// udp side has multiple readers (linux Queues opens exactly n or
-		// errors; every other platform already clamped routines to 1 above).
-		// If a platform ever returns fewer queues than routines with
-		// SO_REUSEPORT sockets already bound, the surplus sockets get no
-		// listenOut and the kernel blackholes every flow it hashes to them —
-		// fail loudly or close the extra sockets instead.
-		f.l.Warn("tun multiqueue is not supported on this platform, falling back to fewer routines",
-			"requested", f.routines, "opened", len(queues))
-		f.routines = len(queues)
-	}
-	f.queues = queues
-
 	metrics.GetOrRegisterGauge("routines", nil).Update(int64(f.routines))

-	for i := range f.queues {
-		f.batchers[i] = batch.NewMultiCoalescer(f.queues[i], f.l)
+	// Prepare n tun queues
+	var reader io.ReadWriteCloser = f.inside
+	for i := 0; i < f.routines; i++ {
+		if i > 0 {
+			reader, err = f.inside.NewMultiQueueReader()
+			if err != nil {
+				return err
+			}
+		}
+		f.readers[i] = reader
 	}

 	// On error the caller owns the cleanup, Control.Start cancels the service context
@@ -328,7 +281,7 @@ func (f *Interface) run() {
 	// Launch n queues to read packets from tun dev
 	for i := 0; i < f.routines; i++ {
 		f.wg.Go(func() {
-			f.listenIn(f.queues[i], i)
+			f.listenIn(f.readers[i], i)
 		})
 	}

@@ -353,31 +306,6 @@ func (f *Interface) onFatal(err error) {
 	}
 }

-type rxContext struct {
-	q       int
-	scratch []byte
-	// nb is a re-usable nonce buffer for decrypt calls to use
-	nb           []byte
-	h            *header.H
-	fwPacket     *firewall.ParsedPacket
-	hostmapCache map[uint32]*HostInfo
-	lhh          *LightHouseHandler
-	ctCache      *firewall.ConntrackCacheTicker
-}
-
-func newRxContext(f *Interface, q int) *rxContext {
-	return &rxContext{
-		q:            q,
-		scratch:      make([]byte, mtu),
-		nb:           make([]byte, 12, 12),
-		h:            &header.H{},
-		fwPacket:     &firewall.ParsedPacket{},
-		hostmapCache: map[uint32]*HostInfo{},
-		lhh:          f.lightHouse.NewRequestHandler(),
-		ctCache:      firewall.NewConntrackCacheTicker(f.ctx, f.l, f.conntrackCacheTimeout),
-	}
-}
-
 func (f *Interface) listenOut(i int) {
 	var li udp.Conn
 	if i > 0 {
@@ -386,20 +314,16 @@ func (f *Interface) listenOut(i int) {
 		li = f.outside
 	}

-	rxc := newRxContext(f, i)
+	ctCache := firewall.NewConntrackCacheTicker(f.ctx, f.l, f.conntrackCacheTimeout)
+	lhh := f.lightHouse.NewRequestHandler()
+	plaintext := make([]byte, udp.MTU)
+	h := &header.H{}
+	fwPacket := &firewall.Packet{}
+	nb := make([]byte, 12, 12)

-	listener := func(fromUdpAddr netip.AddrPort, payload []byte) {
-		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, payload, rxc)
-	}
-
-	flusher := func() {
-		if err := f.batchers[i].Flush(); err != nil {
-			f.l.Error("Failed to flush tun coalescer", "error", err)
-		}
-		clear(rxc.hostmapCache)
-	}
-
-	err := li.ListenOut(listener, flusher)
+	err := li.ListenOut(func(fromUdpAddr netip.AddrPort, payload []byte) {
+		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, plaintext[:0], payload, h, fwPacket, lhh, nb, i, ctCache.Get())
+	})

 	// An error after teardown began is shutdown noise, the closed flag covers resources
 	// Close releases itself and the cancelled ctx covers ones torn down by their owners
@@ -412,42 +336,16 @@ func (f *Interface) listenOut(i int) {
 	f.l.Debug("underlay reader is done", "reader", i)
 }

-func (f *Interface) pinThisThread(i int) {
-	var cpu int
-	if n := len(f.cpuAffinity); n > 0 {
-		// Explicit tun.cpu_affinity list wins; parseCpuAffinity already
-		// validated the entries against the allowed CPU set.
-		cpu = f.cpuAffinity[i%n]
-	} else if allowed, err := util.AllowedCPUs(); err == nil && len(allowed) > 0 {
-		// Default: spread queues across the CPUs we're actually allowed to
-		// run on. Under a cpuset/taskset mask these aren't 0..NumCPU-1, so
-		// i % NumCPU would pick unrunnable IDs and every pin would fail.
-		cpu = allowed[i%len(allowed)]
-	} else {
-		cpu = i % runtime.NumCPU()
-	}
-	if err := util.PinThreadToCPU(cpu); err != nil {
-		f.l.Warn("failed to pin tun reader to CPU", "queue", i, "cpu", cpu, "err", err)
-	}
-}
-
-func (f *Interface) listenIn(queue tio.Queue, i int) {
-	// Pinning this thread (and goroutine) to a single CPU keeps every sendmmsg from this goroutine going through the
-	// same TX ring on the nic, so the wire sees per-flow order. Skip entirely when tun.pin_threads is false.
-	if f.pinThreads {
-		f.pinThisThread(i)
-	}
-
-	rejectBuf := make([]byte, mtu)
-	arenaSize := batch.SendBatchCap * (udp.MTU + 32)
-	sb := batch.NewSendBatch(f.writers[i], batch.SendBatchCap, arenaSize)
-	fwPacket := &firewall.ParsedPacket{}
+func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
+	packet := make([]byte, mtu)
+	out := make([]byte, mtu)
+	fwPacket := &firewall.Packet{}
 	nb := make([]byte, 12, 12)

 	conntrackCache := firewall.NewConntrackCacheTicker(f.ctx, f.l, f.conntrackCacheTimeout)

 	for {
-		pkts, err := queue.Read()
+		n, err := reader.Read(packet)
 		if err != nil {
 			// Same shutdown noise handling as listenOut
 			if !f.closed.Load() && f.ctx.Err() == nil {
@@ -457,35 +355,12 @@ func (f *Interface) listenIn(queue tio.Queue, i int) {
 			break
 		}

-		for _, pkt := range pkts {
-			f.consumeInsidePacket(pkt, fwPacket, nb, sb, rejectBuf, i, conntrackCache.Get())
-			// Flush incrementally once a full sendmmsg batch has
-			// accumulated so the first packets of a deep read drain
-			// hit the wire while the rest are still being encrypted.
-			if sb.Len() >= batch.SendBatchCap {
-				f.flushSendBatch(sb, i)
-			}
-		}
-		f.flushSendBatch(sb, i)
+		f.consumeInsidePacket(packet[:n], fwPacket, nb, out, i, conntrackCache.Get())
 	}

 	f.l.Debug("overlay reader is done", "reader", i)
 }

-// flushSendBatch drains sb to the underlay and accounts for anything it could not deliver. A shortfall means
-// specific destinations were undeliverable (a stale remote, a reject rule), which the backend logs per peer at
-// debug; here it is only a counter, so one unreachable peer cannot spam a log line per batch.
-func (f *Interface) flushSendBatch(sb *batch.SendBatch, q int) {
-	queued := sb.Len()
-	written, err := sb.Flush()
-	if err != nil {
-		f.l.Error("Failed to write outgoing batch", "error", err, "writer", q)
-	}
-	if dropped := queued - written; dropped > 0 {
-		f.metricTxDropped.Inc(int64(dropped))
-	}
-}
-
 func (f *Interface) RegisterConfigChangeCallbacks(c *config.C) {
 	c.RegisterReloadCallback(f.reloadFirewall)
 	c.RegisterReloadCallback(f.reloadSendRecvError)
@@ -1,146 +0,0 @@
-package iputil
-
-import (
-	"encoding/binary"
-
-	"github.com/slackhq/nebula/overlay/checksum"
-	"golang.org/x/net/ipv4"
-	"golang.org/x/net/ipv6"
-)
-
-const udpHeaderLen = 8
-
-// SetTransportChecksum recomputes the TCP or UDP checksum of an IPv4 or IPv6
-// packet in place.
-//
-// A kernel that offloads checksums to the NIC hands a packet to a tun with the
-// transport checksum unfinished: only the pseudo-header sum is in the field and
-// the rest is left for hardware that a tun does not have. A packet written
-// straight back to that tun is dropped on re-entry unless the checksum is
-// completed first. ICMP is left alone; it arrived complete on the kernels this
-// was measured against.
-//
-// So is any packet whose transport header cannot be located: fragments, unknown
-// extension headers and truncated packets. An IPv6 fragment header is declined
-// even when it carries the whole datagram (RFC 6946 atomic fragment), because
-// the walk reports only that a fragment header was present.
-func SetTransportChecksum(packet []byte) {
-	if len(packet) < 1 {
-		return
-	}
-	switch int(packet[0] >> 4) {
-	case ipv4.Version:
-		setTransportChecksum4(packet)
-	case ipv6.Version:
-		setTransportChecksum6(packet)
-	}
-}
-
-func setTransportChecksum4(packet []byte) {
-	if len(packet) < ipv4.HeaderLen {
-		return
-	}
-	ihl := int(packet[0]&0x0f) << 2
-	end := int(binary.BigEndian.Uint16(packet[2:4]))
-	if ihl < ipv4.HeaderLen || end < ihl || end > len(packet) {
-		return
-	}
-	// The checksum covers the whole datagram, which a fragment (MF set or a
-	// non-zero offset) does not carry.
-	if binary.BigEndian.Uint16(packet[6:8])&0x3fff != 0 {
-		return
-	}
-
-	transport, ok := transportExtent(packet[ihl:end], packet[9])
-	if !ok {
-		return
-	}
-	csum := ipv4PseudoheaderChecksum(packet[12:16], packet[16:20], uint32(packet[9]), uint32(len(transport)))
-	writeTransportChecksum(transport, packet[9], csum)
-}
-
-func setTransportChecksum6(packet []byte) {
-	if len(packet) < ipv6.HeaderLen {
-		return
-	}
-	end := ipv6.HeaderLen + int(binary.BigEndian.Uint16(packet[4:6]))
-	if end > len(packet) {
-		return
-	}
-
-	// The checksum covers the whole datagram, which a fragment does not carry.
-	// An unknown extension header hides where the transport header starts. A
-	// chain longer than the walk's budget ends it early, at an offset that was
-	// never checked against the packet.
-	proto, offset, _, anyFragment, err := IPv6FindUpperProtocol(packet[:end])
-	if err != nil || anyFragment || offset >= end {
-		return
-	}
-
-	transport, ok := transportExtent(packet[offset:end], proto)
-	if !ok {
-		return
-	}
-	csum := ipv6PseudoheaderChecksum(packet[8:24], packet[24:40], uint32(proto), uint32(len(transport)))
-	writeTransportChecksum(transport, proto, csum)
-}
-
-// transportExtent narrows a segment to the length its own header declares. UDP
-// carries a Length field, and RFC 768 and RFC 8200 section 8.1 both make that
-// field, not the IP payload extent, the length the pseudo-header counts and the
-// checksum covers; a datagram padded out to a link's minimum frame is the usual
-// way the two differ. TCP has no such field, so its segment runs to the end of
-// the IP payload. A Length that overruns the bytes IP delivered describes a
-// datagram that is not there.
-func transportExtent(transport []byte, proto uint8) ([]byte, bool) {
-	if proto != IPProtocolUDP {
-		return transport, true
-	}
-	if len(transport) < udpHeaderLen {
-		return nil, false
-	}
-	ulen := int(binary.BigEndian.Uint16(transport[4:6]))
-	if ulen < udpHeaderLen || ulen > len(transport) {
-		return nil, false
-	}
-	return transport[:ulen], true
-}
-
-// writeTransportChecksum stores the checksum of transport, taken over the
-// pseudo-header sum csum, in the header's checksum field. A UDP checksum that
-// computes to zero goes on the wire as 0xffff: zero means no checksum was
-// computed (RFC 768), and over IPv6 the checksum is mandatory (RFC 8200
-// section 8.1).
-func writeTransportChecksum(transport []byte, proto uint8, csum uint32) {
-	var at, minLen int
-	switch proto {
-	case IPProtocolTCP:
-		at, minLen = 16, 20
-	case IPProtocolUDP:
-		at, minLen = 6, udpHeaderLen
-	default:
-		return
-	}
-	if len(transport) < minLen {
-		return
-	}
-
-	transport[at], transport[at+1] = 0, 0
-	sum := ^checksum.Checksum(transport, fold(csum))
-	if sum == 0 && proto == IPProtocolUDP {
-		sum = 0xffff
-	}
-	binary.BigEndian.PutUint16(transport[at:], sum)
-}
-
-// fold reduces a pseudo-header sum to the 16 bit seed Checksum takes. Carrying
-// the high half back into the low half is what keeps the reduction lossless, so
-// the seed sums exactly as the wider value would; 0xffff is its fixed point.
-// Every term of that sum comes from a 16 bit field, so it stays far below the
-// width at which the accumulator would wrap.
-func fold(csum uint32) uint16 {
-	for csum > 0xffff {
-		csum = (csum >> 16) + (csum & 0xffff)
-	}
-	return uint16(csum)
-}
@@ -1,242 +0,0 @@
-package iputil
-
-import (
-	"encoding/binary"
-	"net"
-	"testing"
-
-	"github.com/google/gopacket"
-	"github.com/google/gopacket/layers"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-	"golang.org/x/net/ipv6"
-)
-
-// serialize builds a packet with gopacket, whose checksums are computed
-// independently of this package.
-func serialize(t *testing.T, ls ...gopacket.SerializableLayer) []byte {
-	buf := gopacket.NewSerializeBuffer()
-	require.NoError(t, gopacket.SerializeLayers(buf, gopacket.SerializeOptions{FixLengths: true, ComputeChecksums: true}, ls...))
-	return append([]byte(nil), buf.Bytes()...)
-}
-
-// withExtensionHeader inserts an 8 byte IPv6 extension header of the given
-// type between the IPv6 header and its payload. The transport checksum does not
-// change: the pseudo-header counts only upper-layer bytes.
-func withExtensionHeader(pkt []byte, typ layers.IPProtocol, hdr [8]byte) []byte {
-	hdr[0] = pkt[6]
-	out := make([]byte, 0, len(pkt)+8)
-	out = append(out, pkt[:40]...)
-	out = append(out, hdr[:]...)
-	out = append(out, pkt[40:]...)
-	out[6] = byte(typ)
-	binary.BigEndian.PutUint16(out[4:6], binary.BigEndian.Uint16(pkt[4:6])+8)
-	return out
-}
-
-// truncate copies the first n bytes into a buffer of exactly that capacity, so
-// a read past the length panics instead of quietly succeeding.
-func truncate(pkt []byte, n int) []byte {
-	out := make([]byte, n)
-	copy(out, pkt)
-	return out
-}
-
-// extChain builds an IPv6 packet fronted by n Destination Options headers. Each
-// points at another one, so the walk spends its whole budget without reaching a
-// transport header. lastExtLen inflates the final header's declared length,
-// which is how the walk ends up past the end of the packet.
-func extChain(n int, lastExtLen byte) []byte {
-	pkt := make([]byte, ipv6.HeaderLen)
-	pkt[0], pkt[6], pkt[7] = 0x60, 60, 64
-	for i := range n {
-		h := make([]byte, 8)
-		h[0] = 60
-		if i == n-1 {
-			h[1] = lastExtLen
-		}
-		pkt = append(pkt, h...)
-	}
-	pkt = append(pkt, make([]byte, 20)...)
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(len(pkt)-ipv6.HeaderLen))
-	return pkt
-}
-
-func TestSetTransportChecksum(t *testing.T) {
-	// Source and destination differ so that a pseudo-header built from the wrong
-	// one, or from the two swapped, does not land on the same checksum anyway.
-	v4 := func(proto layers.IPProtocol) *layers.IPv4 {
-		return &layers.IPv4{Version: 4, TTL: 64, Id: 0x1234, Protocol: proto, SrcIP: net.IPv4(192, 0, 2, 1).To4(), DstIP: net.IPv4(198, 51, 100, 2).To4()}
-	}
-	v6 := func(proto layers.IPProtocol) *layers.IPv6 {
-		return &layers.IPv6{Version: 6, HopLimit: 64, NextHeader: proto, SrcIP: net.ParseIP("2001:db8::1"), DstIP: net.ParseIP("2001:db8:1::2")}
-	}
-	tcp := func(ip gopacket.NetworkLayer) *layers.TCP {
-		l := &layers.TCP{SrcPort: 49152, DstPort: 443, SYN: true, Window: 65535}
-		require.NoError(t, l.SetNetworkLayerForChecksum(ip))
-		return l
-	}
-	udp := func(ip gopacket.NetworkLayer) *layers.UDP {
-		l := &layers.UDP{SrcPort: 49152, DstPort: 53}
-		require.NoError(t, l.SetNetworkLayerForChecksum(ip))
-		return l
-	}
-	payload := gopacket.Payload("self")
-	nop := layers.IPv4Option{OptionType: 1, OptionLength: 1}
-
-	ip4tcp := v4(layers.IPProtocolTCP)
-	ip4opts := v4(layers.IPProtocolTCP)
-	ip4opts.Options = []layers.IPv4Option{nop, nop, nop, nop}
-	ip4udp := v4(layers.IPProtocolUDP)
-	ip6tcp := v6(layers.IPProtocolTCP)
-	ip6udp := v6(layers.IPProtocolUDP)
-	hopByHop := [8]byte{0, 0, 1, 4} // next header, length 0, PadN of 4
-
-	// Bytes past the length the IP header declares are not part of the
-	// datagram and must not be summed.
-	trailing4 := append(serialize(t, ip4tcp, tcp(ip4tcp), payload), []byte("trailing")...)
-	trailing6 := append(serialize(t, ip6tcp, tcp(ip6tcp), payload), []byte("trailing")...)
-
-	// A datagram padded out past the length UDP declares: the pseudo-header
-	// counts the UDP Length field, so the checksum is the unpadded one.
-	padded4 := append(serialize(t, ip4udp, udp(ip4udp), payload), []byte("pad!")...)
-	binary.BigEndian.PutUint16(padded4[2:4], uint16(len(padded4)))
-	padded6 := append(serialize(t, ip6udp, udp(ip6udp), payload), []byte("pad!")...)
-	binary.BigEndian.PutUint16(padded6[4:6], uint16(len(padded6)-ipv6.HeaderLen))
-
-	// Corrupting the checksum and asking for it back must yield gopacket's
-	// packet, byte for byte.
-	recomputed := []struct {
-		name  string
-		pkt   []byte
-		cksum int
-	}{
-		{"v4 tcp", serialize(t, ip4tcp, tcp(ip4tcp), payload), 20 + 16},
-		{"v4 tcp with ip options", serialize(t, ip4opts, tcp(ip4opts), payload), 24 + 16},
-		{"v4 udp", serialize(t, ip4udp, udp(ip4udp), payload), 20 + 6},
-		{"v4 tcp header only", serialize(t, ip4tcp, tcp(ip4tcp)), 20 + 16},
-		{"v4 udp header only", serialize(t, ip4udp, udp(ip4udp)), 20 + 6},
-		{"v6 tcp", serialize(t, ip6tcp, tcp(ip6tcp), payload), 40 + 16},
-		{"v6 udp", serialize(t, ip6udp, udp(ip6udp), payload), 40 + 6},
-		{"v6 udp header only", serialize(t, ip6udp, udp(ip6udp)), 40 + 6},
-		{"v6 tcp behind hop-by-hop", withExtensionHeader(serialize(t, ip6tcp, tcp(ip6tcp), payload), layers.IPProtocolIPv6HopByHop, hopByHop), 48 + 16},
-		{"v4 tcp with bytes past the total length", trailing4, 20 + 16},
-		{"v6 tcp with bytes past the payload length", trailing6, 40 + 16},
-		{"v4 udp padded past its declared length", padded4, 20 + 6},
-		{"v6 udp padded past its declared length", padded6, 40 + 6},
-	}
-	for _, tt := range recomputed {
-		t.Run(tt.name, func(t *testing.T) {
-			got := append([]byte(nil), tt.pkt...)
-			binary.BigEndian.PutUint16(got[tt.cksum:], 0x1234)
-			require.NotEqual(t, tt.pkt, got)
-			SetTransportChecksum(got)
-			assert.Equal(t, tt.pkt, got)
-		})
-	}
-
-	ip4frag := v4(layers.IPProtocolTCP)
-	ip4frag.Flags = layers.IPv4MoreFragments
-	ip4later := v4(layers.IPProtocolTCP)
-	ip4later.FragOffset = 1
-	ip4icmp := v4(layers.IPProtocolICMPv4)
-
-	badIHL := serialize(t, ip4tcp, tcp(ip4tcp), payload)
-	badIHL[0] = 0x44 // header length 16, shorter than an ipv4 header
-	shortTotalLen := serialize(t, ip4tcp, tcp(ip4tcp), payload)
-	binary.BigEndian.PutUint16(shortTotalLen[2:4], 10) // shorter than the header it introduces
-	cutTCP := serialize(t, ip4tcp, tcp(ip4tcp), payload)
-	binary.BigEndian.PutUint16(cutTCP[2:4], 20+19) // one byte short of a tcp header
-	cutTCP = truncate(cutTCP, 20+19)
-	cutUDP := serialize(t, ip4udp, udp(ip4udp), payload)
-	binary.BigEndian.PutUint16(cutUDP[2:4], 20+7) // one byte short of a udp header
-	cutUDP = truncate(cutUDP, 20+7)
-	// Two bytes short, so a transport header survives whole and the minimum
-	// length check cannot stand in for the bounds check.
-	cutV6 := truncate(serialize(t, ip6tcp, tcp(ip6tcp), payload), 62)
-	fragment := [8]byte{0, 0, 0, 1, 0, 0, 0, 1} // next header, reserved, offset 0 with M set, id
-	overrun4 := serialize(t, ip4udp, udp(ip4udp), payload)
-	binary.BigEndian.PutUint16(overrun4[24:26], uint16(len(overrun4)-20+1)) // one byte past what ip delivered
-	overrun6 := serialize(t, ip6udp, udp(ip6udp), payload)
-	binary.BigEndian.PutUint16(overrun6[44:46], uint16(len(overrun6)-ipv6.HeaderLen+1))
-	shortUDPLen := serialize(t, ip4udp, udp(ip4udp), payload)
-	binary.BigEndian.PutUint16(shortUDPLen[24:26], 7) // shorter than the header it counts
-
-	// Where the checksum cannot be completed the packet is left as it came.
-	untouched := []struct {
-		name  string
-		pkt   []byte
-		cksum int
-	}{
-		{"v4 first fragment", serialize(t, ip4frag, tcp(ip4frag), payload), 20 + 16},
-		{"v4 later fragment", serialize(t, ip4later, tcp(ip4later), payload), 20 + 16},
-		{"v4 icmp", serialize(t, ip4icmp, &layers.ICMPv4{TypeCode: layers.CreateICMPv4TypeCode(8, 0), Id: 1, Seq: 1}, payload), 20 + 2},
-		{"v4 header length below the minimum", badIHL, 20 + 16},
-		{"v4 total length below the header length", shortTotalLen, 20 + 16},
-		{"v4 truncated below its total length", truncate(serialize(t, ip4tcp, tcp(ip4tcp), payload), 30), -1},
-		{"v4 tcp header cut short", cutTCP, 20 + 16},
-		{"v4 udp header cut short", cutUDP, -1},
-		{"v6 fragment", withExtensionHeader(serialize(t, ip6tcp, tcp(ip6tcp), payload), layers.IPProtocolIPv6Fragment, fragment), 48 + 16},
-		{"v6 truncated below its payload length", truncate(serialize(t, ip6tcp, tcp(ip6tcp), payload), 50), -1},
-		{"v6 truncated with a whole transport header still present", cutV6, 40 + 16},
-		{"v6 extension header chain longer than the walk", extChain(9, 0), 112 + 16},
-		{"v6 extension header chain running past the packet", extChain(8, 255), 104 + 16},
-		{"v4 udp length past the end of the datagram", overrun4, 20 + 6},
-		{"v6 udp length past the end of the datagram", overrun6, 40 + 6},
-		{"v4 udp length below a udp header", shortUDPLen, 20 + 6},
-	}
-	for _, tt := range untouched {
-		t.Run(tt.name, func(t *testing.T) {
-			if tt.cksum >= 0 {
-				binary.BigEndian.PutUint16(tt.pkt[tt.cksum:], 0x1234)
-			}
-			want := append([]byte(nil), tt.pkt...)
-			SetTransportChecksum(tt.pkt)
-			assert.Equal(t, want, tt.pkt)
-		})
-	}
-
-	t.Run("too short to carry a header", func(t *testing.T) {
-		for _, pkt := range [][]byte{nil, {}, {0x45}, {0x60}} {
-			assert.NotPanics(t, func() { SetTransportChecksum(pkt) })
-		}
-	})
-
-	t.Run("tcp checksum of zero goes out as zero", func(t *testing.T) {
-		pkt := serialize(t, ip4tcp, tcp(ip4tcp), gopacket.Payload{0, 0})
-		c := binary.BigEndian.Uint16(pkt[36:38])
-		require.NotZero(t, c)
-		// Only udp reserves zero to mean "not computed", so tcp keeps it.
-		binary.BigEndian.PutUint16(pkt[40:42], c)
-		SetTransportChecksum(pkt)
-		assert.Zero(t, binary.BigEndian.Uint16(pkt[36:38]))
-	})
-
-	t.Run("udp checksum of zero goes out as 0xffff", func(t *testing.T) {
-		pkt := serialize(t, ip4udp, udp(ip4udp), gopacket.Payload{0, 0})
-		c := binary.BigEndian.Uint16(pkt[26:28])
-		require.NotZero(t, c)
-		// The one's complement sum is now 0xffff - c; adding c to the payload
-		// makes it 0xffff, whose complement is zero.
-		binary.BigEndian.PutUint16(pkt[28:30], c)
-		SetTransportChecksum(pkt)
-		assert.Equal(t, uint16(0xffff), binary.BigEndian.Uint16(pkt[26:28]))
-	})
-}
-
-func TestFold(t *testing.T) {
-	// 0xffff is the fold's fixed point, so a loop bound one notch tight never
-	// terminates on it.
-	for _, tt := range []struct {
-		in   uint32
-		want uint16
-	}{
-		{0, 0},
-		{0xffff, 0xffff},
-		{0x10000, 1},
-		{0x1fffe, 0xffff},
-		{0xffffffff, 0xffff},
-	} {
-		assert.Equal(t, tt.want, fold(tt.in))
-	}
-}
@@ -27,13 +27,6 @@ const (
 	maxIPv6RejectPacketSize = ipv6.HeaderLen + 8 + 1000

 	MaxRejectPacketSize = maxIPv6RejectPacketSize
-
-	IPProtocolICMP        = 1
-	IPProtocolICMPv6      = 58
-	IPProtocolTCP         = 6
-	IPProtocolUDP         = 17
-	ICMPv6TypeEchoRequest = 128
-	ICMPv6TypeEchoReply   = 129
 )

 func CreateRejectPacket(packet []byte, out []byte) []byte {
@@ -211,7 +204,7 @@ func ipv4CreateRejectTCPPacket(packet []byte, out []byte) []byte {
 }

 func ipv6CreateRejectPacket(packet []byte, out []byte) []byte {
-	proto, offset, isFragment, _, err := IPv6FindUpperProtocol(packet)
+	proto, offset, isFragment, err := IPv6FindUpperProtocol(packet)
 	if err != nil || isFragment {
 		return nil
 	}
@@ -353,38 +346,36 @@ func ipv6CreateRejectTCPPacket(packet []byte, out []byte, offset int) []byte {
 // protocol and offset points at the fragment header, there is no transport header to locate. Returns
 // ErrIPv6CouldNotFindPayload if packet is smaller than an ipv6 header or the chain is truncated before a
 // terminal protocol is reached.
-func IPv6FindUpperProtocol(packet []byte) (nextHeader uint8, offset int, isFragment bool, anyFragment bool, err error) {
-	const maxIPv6ExtHeaders = 8
+func IPv6FindUpperProtocol(packet []byte) (nextHeader uint8, offset int, isFragment bool, err error) {
 	if len(packet) < ipv6.HeaderLen {
-		return 0, 0, false, false, ErrIPv6CouldNotFindPayload
+		return 0, 0, false, ErrIPv6CouldNotFindPayload
 	}
 	nextHeader = packet[6]
 	offset = ipv6.HeaderLen

-	for range maxIPv6ExtHeaders {
+	for {
 		switch nextHeader {
 		case 0, 43, 60: // Hop-by-Hop, Routing, Destination
 			if len(packet) < offset+2 {
-				return nextHeader, offset, isFragment, anyFragment, ErrIPv6CouldNotFindPayload
+				return nextHeader, offset, isFragment, ErrIPv6CouldNotFindPayload
 			}
 			nextHeader = packet[offset]
 			offset += (int(packet[offset+1]) + 1) << 3

 		case 44: // Fragment
 			if len(packet) < offset+8 {
-				return nextHeader, offset, isFragment, anyFragment, ErrIPv6CouldNotFindPayload
+				return nextHeader, offset, isFragment, ErrIPv6CouldNotFindPayload
 			}
-			anyFragment = true
 			// Non-first fragments carry no transport header, report the fragmented protocol and stop
 			if packet[offset+2] != 0 || packet[offset+3]&0xf8 != 0 {
-				return packet[offset], offset, true, anyFragment, nil
+				return packet[offset], offset, true, nil
 			}
 			nextHeader = packet[offset]
 			offset += 8

 		case 51: // AH
 			if len(packet) < offset+2 {
-				return nextHeader, offset, isFragment, anyFragment, ErrIPv6CouldNotFindPayload
+				return nextHeader, offset, isFragment, ErrIPv6CouldNotFindPayload
 			}
 			nextHeader = packet[offset]
 			offset += (int(packet[offset+1]) + 2) << 2
@@ -393,12 +384,11 @@ func IPv6FindUpperProtocol(packet []byte) (nextHeader uint8, offset int, isFragm
 			// A prior extension header can declare a length that advances offset past the packet. The terminal
 			// protocol's header isn't actually here, so treat the chain as truncated rather than classifying it.
 			if offset > len(packet) {
-				return nextHeader, offset, isFragment, anyFragment, ErrIPv6CouldNotFindPayload
+				return nextHeader, offset, isFragment, ErrIPv6CouldNotFindPayload
 			}
-			return nextHeader, offset, isFragment, anyFragment, nil
+			return nextHeader, offset, isFragment, nil
 		}
 	}
-	return nextHeader, offset, isFragment, anyFragment, nil
 }

 func CreateICMPEchoResponse(packet, out []byte) []byte {
@@ -1,7 +1,6 @@
 package iputil

 import (
-	"bytes"
 	"encoding/binary"
 	"net"
 	"testing"
@@ -181,46 +180,6 @@ func Test_CreateRejectPacket_NoICMPError(t *testing.T) {
 	}
 }

-// Test_CreateRejectPacket_RespectsCap ensures it is impossible for
-// an oversized ICMPv6 reject to overwrite the neighbor segment's bytes.
-func Test_CreateRejectPacket_RespectsCap(t *testing.T) {
-	src := net.ParseIP("fd00::1")
-	dst := net.ParseIP("fd00::2")
-
-	// Inner IPv6 UDP packet. An ICMPv6 reject copies the whole inner packet
-	// plus a 48-byte header (40 IPv6 + 8 ICMPv6), so it needs 48 more bytes
-	// than the inner packet length.
-	inner := makeIPv6Packet(src, dst, 17, make([]byte, 20))
-
-	// The ciphertext scratch reused as the reject buffer is the received
-	// datagram: 16-byte Nebula header + inner + 16-byte AEAD tag. That is only
-	// 32 bytes of slack, so a full ICMPv6 reject overruns it by 16 bytes.
-	const nebulaOverhead = 32
-	segLen := len(inner) + nebulaOverhead
-
-	// Shared backing row laid out as [segment][neighbor's 16-byte Nebula header].
-	const neighborHdr = 16
-	sentinel := bytes.Repeat([]byte{0xAB}, neighborHdr)
-
-	// Uncapped: the slice's capacity reaches into the neighbor, reproducing
-	// the overrun that silently drops the neighbor packet.
-	backing := make([]byte, segLen+neighborHdr)
-	copy(backing[segLen:], sentinel)
-	reject := CreateRejectPacket(inner, backing[:segLen])
-	assert.NotNil(t, reject, "uncapped buffer reaches into the neighbor, so the reject is built")
-	assert.NotEqual(t, sentinel, backing[segLen:segLen+neighborHdr],
-		"without the cap the oversized reject overruns into the neighbor segment")
-
-	// Capped (the fix): cap==len, so the builder cannot exceed the segment. The
-	// reject does not fit, so it is refused rather than corrupting the neighbor.
-	backing = make([]byte, segLen+neighborHdr)
-	copy(backing[segLen:], sentinel)
-	reject = CreateRejectPacket(inner, backing[:segLen:segLen])
-	assert.Nil(t, reject, "capped segment is 16 bytes too small for a full ICMPv6 reject, so it is refused")
-	assert.Equal(t, sentinel, backing[segLen:segLen+neighborHdr],
-		"capped segment must leave the neighbor untouched")
-}
-
 func makeIPv6Packet(src, dst net.IP, nextHeader uint8, payload []byte) []byte {
 	b := make([]byte, ipv6.HeaderLen+len(payload))
 	b[0] = ipv6.Version << 4
@@ -537,27 +496,26 @@ func Test_IPv6FindUpperProtocol(t *testing.T) {
 		wantProto    uint8
 		wantOffset   int
 		wantFragment bool
-		wantAnyFrag  bool
 		wantErr      error
 	}{
-		{"plain udp", 17, transport, 17, ipv6.HeaderLen, false, false, nil},
-		{"hop-by-hop then tcp", 0, append(extToTCP, transport...), 6, ipv6.HeaderLen + 8, false, false, nil},
-		{"routing then tcp", 43, append(extToTCP, transport...), 6, ipv6.HeaderLen + 8, false, false, nil},
-		{"destination then udp", 60, append(extToUDP, transport...), 17, ipv6.HeaderLen + 8, false, false, nil},
-		{"hop-by-hop, routing, then tcp", 0, append(append(extToRouting, extToTCP...), transport...), 6, ipv6.HeaderLen + 16, false, false, nil},
-		{"ah then udp", 51, append(ahToUDP, transport...), 17, ipv6.HeaderLen + 8, false, false, nil},
-		{"first fragment walks to transport", 44, append(firstFragToUDP, transport...), 17, ipv6.HeaderLen + 8, false, true, nil},
-		{"non-first fragment stops", 44, append(nonFirstFrag, transport...), 17, ipv6.HeaderLen, true, true, nil},
-		{"unknown protocol is terminal", 132, transport, 132, ipv6.HeaderLen, false, false, nil}, // SCTP
-		{"truncated extension header", 0, nil, 0, ipv6.HeaderLen, false, false, ErrIPv6CouldNotFindPayload},
+		{"plain udp", 17, transport, 17, ipv6.HeaderLen, false, nil},
+		{"hop-by-hop then tcp", 0, append(extToTCP, transport...), 6, ipv6.HeaderLen + 8, false, nil},
+		{"routing then tcp", 43, append(extToTCP, transport...), 6, ipv6.HeaderLen + 8, false, nil},
+		{"destination then udp", 60, append(extToUDP, transport...), 17, ipv6.HeaderLen + 8, false, nil},
+		{"hop-by-hop, routing, then tcp", 0, append(append(extToRouting, extToTCP...), transport...), 6, ipv6.HeaderLen + 16, false, nil},
+		{"ah then udp", 51, append(ahToUDP, transport...), 17, ipv6.HeaderLen + 8, false, nil},
+		{"first fragment walks to transport", 44, append(firstFragToUDP, transport...), 17, ipv6.HeaderLen + 8, false, nil},
+		{"non-first fragment stops", 44, append(nonFirstFrag, transport...), 17, ipv6.HeaderLen, true, nil},
+		{"unknown protocol is terminal", 132, transport, 132, ipv6.HeaderLen, false, nil}, // SCTP
+		{"truncated extension header", 0, nil, 0, ipv6.HeaderLen, false, ErrIPv6CouldNotFindPayload},
 		// Destination Options with a declared length (255+1)*8 = 2048 that runs past the 48 byte buffer, next = SCTP
-		{"extension length past buffer", 60, []byte{132, 255, 0, 0, 0, 0, 0, 0}, 132, ipv6.HeaderLen + 2048, false, false, ErrIPv6CouldNotFindPayload},
+		{"extension length past buffer", 60, []byte{132, 255, 0, 0, 0, 0, 0, 0}, 132, ipv6.HeaderLen + 2048, false, ErrIPv6CouldNotFindPayload},
 	}

 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			packet := makeIPv6Packet(src, dst, tt.nextHeader, tt.payload)
-			proto, offset, isFragment, anyFragment, err := IPv6FindUpperProtocol(packet)
+			proto, offset, isFragment, err := IPv6FindUpperProtocol(packet)
 			if tt.wantErr != nil {
 				assert.ErrorIs(t, err, tt.wantErr)
 				return
@@ -566,13 +524,12 @@ func Test_IPv6FindUpperProtocol(t *testing.T) {
 			assert.Equal(t, tt.wantProto, proto)
 			assert.Equal(t, tt.wantOffset, offset)
 			assert.Equal(t, tt.wantFragment, isFragment)
-			assert.Equal(t, tt.wantAnyFrag, anyFragment)
 		})
 	}

 	// A packet smaller than an ipv6 header must error rather than panic reading byte 6
 	t.Run("shorter than ipv6 header", func(t *testing.T) {
-		_, _, _, _, err := IPv6FindUpperProtocol(make([]byte, 6))
+		_, _, _, err := IPv6FindUpperProtocol(make([]byte, 6))
 		assert.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 	})
 }
@@ -513,15 +513,17 @@ func (lh *LightHouse) QueryServer(vpnAddr netip.Addr) {
 }

 func (lh *LightHouse) QueryCache(vpnAddrs []netip.Addr) *RemoteList {
-	rl, ok := lh.findRemoteList(vpnAddrs)
-	if ok {
-		return rl
+	lh.RLock()
+	if v, ok := lh.addrMap[vpnAddrs[0]]; ok {
+		lh.RUnlock()
+		return v
 	}
+	lh.RUnlock()

 	lh.Lock()
 	defer lh.Unlock()
 	// Add an entry if we don't already have one
-	return lh.unlockedGetRemoteList(vpnAddrs) //todo this re-calls unlockedFindRemoteList
+	return lh.unlockedGetRemoteList(vpnAddrs) //todo CERT-V2 this contains addrmap lookups we could potentially skip
 }

 // queryAndPrepMessage is a lock helper on RemoteList, assisting the caller to build a lighthouse message containing
@@ -667,58 +669,23 @@ func (lh *LightHouse) addCalculatedRemotes(vpnAddr netip.Addr) bool {
 	return len(calculatedV4) > 0 || len(calculatedV6) > 0
 }

-func (lh *LightHouse) findRemoteList(vpnAddrs []netip.Addr) (*RemoteList, bool) {
-	lh.RLock()
-	defer lh.RUnlock()
-	return lh.unlockedFindRemoteList(vpnAddrs)
-}
-
-// unlockedFindRemoteList checks addrMap for each of vpnAddrs. It returns the first RemoteList found,
-// and true if that RemoteList is present for all vpnAddrs.
-// If false, it means the addrMap, and possibly the RemoteList, need to be corrected.
-func (lh *LightHouse) unlockedFindRemoteList(vpnAddrs []netip.Addr) (*RemoteList, bool) {
-	var am *RemoteList
-	//todo: if a host with addresses A and B is "split", so it only has address A and a new host has only address B
-	//todo: we don't handly that correctly, I'm pretty sure.
-	missingOrDifferent := false
-	for _, addr := range vpnAddrs {
-		found, ok := lh.addrMap[addr]
-		if !ok {
-			missingOrDifferent = true
-		} else if am == nil {
-			am = found //the first list we find wins
-		} else if am != found {
-			missingOrDifferent = true
-		}
-	}
-	return am, !missingOrDifferent
-}
-
 // unlockedGetRemoteList assumes you have the lh lock
 func (lh *LightHouse) unlockedGetRemoteList(allAddrs []netip.Addr) *RemoteList {
 	// before we go and make a new remotelist, we need to make sure we don't have one for any of this set of vpnaddrs yet
-	am, ok := lh.unlockedFindRemoteList(allAddrs)
-
-	// we failed to find any RemoteLists: make a new one, fill out the addrMap
-	if am == nil {
-		am = NewRemoteList(allAddrs, lh.shouldAdd)
-		for _, addr := range allAddrs {
-			lh.addrMap[addr] = am
-		}
-		return am
-	}
-
-	// we found one! Do we need to fix it?
-	if !ok {
-		am.Lock()
-		am.vpnAddrs = make([]netip.Addr, len(allAddrs))
-		copy(am.vpnAddrs, allAddrs)
-		am.Unlock()
-		for _, addr := range allAddrs {
-			lh.addrMap[addr] = am
+	for i, addr := range allAddrs {
+		am, ok := lh.addrMap[addr]
+		if ok {
+			if i != 0 {
+				lh.addrMap[allAddrs[0]] = am
+			}
+			return am
 		}
 	}

+	am := NewRemoteList(allAddrs, lh.shouldAdd)
+	for _, addr := range allAddrs {
+		lh.addrMap[addr] = am
+	}
 	return am
 }

@@ -498,7 +498,7 @@ type testEncWriter struct {
 	protocolVersion cert.Version
 }

-func (tw *testEncWriter) SendVia(via *HostInfo, relay *Relay, ad, nb, out []byte, nocopy bool, q int) {
+func (tw *testEncWriter) SendVia(via *HostInfo, relay *Relay, ad, nb, out []byte, nocopy bool) {
 }
 func (tw *testEncWriter) Handshake(vpnIp netip.Addr) {
 }
@@ -738,123 +738,3 @@ func TestLighthouse_DeletesWork(t *testing.T) {
 	out = lh.Query(testHost)
 	assert.Nil(t, out)
 }
-
-// newLHHostUpdateV2 sends a v2-style HostUpdateNotification where the sending tunnel carries
-// multiple vpn addrs (a dual-stack v2 cert). Details.VpnAddr is left blank like SendUpdate does.
-func newLHHostUpdateV2(fromAddr netip.AddrPort, vpnAddrs []netip.Addr, addrs []netip.AddrPort, lhh *LightHouseHandler) {
-	req := &NebulaMeta{
-		Type:    NebulaMeta_HostUpdateNotification,
-		Details: &NebulaMetaDetails{},
-	}
-	for _, v := range addrs {
-		if v.Addr().Is4() {
-			req.Details.V4AddrPorts = append(req.Details.V4AddrPorts, netAddrToProtoV4AddrPort(v.Addr(), v.Port()))
-		} else {
-			req.Details.V6AddrPorts = append(req.Details.V6AddrPorts, netAddrToProtoV6AddrPort(v.Addr(), v.Port()))
-		}
-	}
-	b, err := req.Marshal()
-	if err != nil {
-		panic(err)
-	}
-	lhh.HandleRequest(fromAddr, vpnAddrs, b, &testEncWriter{})
-}
-
-func newIssue1868Lighthouse(t *testing.T) (*LightHouse, *LightHouseHandler) {
-	l := test.NewLogger()
-	c := config.NewC(l)
-	c.Settings["lighthouse"] = map[string]any{"am_lighthouse": true}
-	c.Settings["listen"] = map[string]any{"port": 4242}
-
-	myVpnNet4 := netip.MustParsePrefix("10.128.0.1/24")
-	myVpnNet6 := netip.MustParsePrefix("fd00::1/64")
-	nt := new(bart.Lite)
-	nt.Insert(myVpnNet4)
-	nt.Insert(myVpnNet6)
-	cs := &CertState{
-		myVpnNetworks:      []netip.Prefix{myVpnNet4, myVpnNet6},
-		myVpnNetworksTable: nt,
-	}
-	lh, err := NewLightHouseFromConfig(t.Context(), l, c, cs, nil, nil)
-	require.NoError(t, err)
-	lh.ifce = &mockEncWriter{}
-	return lh, lh.NewRequestHandler()
-}
-
-// Scenario A: host registers via v2 (both addrs), then a v1 handshake with the same host completes on
-// the lighthouse (rehandshake after cert renewal, relay-initiated handshake, traffic to the LH's v4
-// addr...). handshake_manager does QueryCache(vpnAddrs) + RefreshFromHandshake(vpnAddrs) with the v1
-// cert's single address, which truncates RemoteList.vpnAddrs.
-func TestLighthouse_Issue1868_V1HandshakeTruncatesVpnAddrs(t *testing.T) {
-	lh, lhh := newIssue1868Lighthouse(t)
-
-	hostV4 := netip.MustParseAddr("10.128.0.3")
-	hostV6 := netip.MustParseAddr("fd00::3")
-	hostUdp := netip.MustParseAddrPort("192.0.2.3:4242")
-	hostLan := netip.MustParseAddrPort("10.0.0.3:4242")
-
-	askerV4 := netip.MustParseAddr("10.128.0.2")
-	askerUdp := netip.MustParseAddrPort("192.0.2.2:4242")
-
-	// Boot: host handshakes with the LH using its v2 cert and sends an update
-	newLHHostUpdateV2(hostUdp, []netip.Addr{hostV4, hostV6}, []netip.AddrPort{hostLan}, lhh)
-
-	// Both addresses resolve
-	r := newLHHostRequest(askerUdp, askerV4, hostV4, lhh)
-	require.NotNil(t, r.msg, "v4 query should be answered")
-	assertIp4InArray(t, r.msg.Details.V4AddrPorts, hostLan)
-
-	r = newLHHostRequest(askerUdp, askerV4, hostV6, lhh)
-	require.NotNil(t, r.msg, "v6 query should be answered before the v1 handshake")
-	assertIp4InArray(t, r.msg.Details.V4AddrPorts, hostLan)
-
-	// Later: a v1 handshake with the same host completes on the LH. This is exactly what
-	// handshake_manager.go does on completion, with the v1 cert's single vpn addr.
-	rl := lh.QueryCache([]netip.Addr{hostV4})
-	rl.RefreshFromHandshake([]netip.Addr{hostV4}, cert.Version1)
-
-	// The host keeps sending v2 updates over its v2 tunnel too
-	newLHHostUpdateV2(hostUdp, []netip.Addr{hostV4, hostV6}, []netip.AddrPort{hostLan}, lhh)
-
-	r = newLHHostRequest(askerUdp, askerV4, hostV4, lhh)
-	require.NotNil(t, r.msg, "v4 query should still be answered")
-	assertIp4InArray(t, r.msg.Details.V4AddrPorts, hostLan)
-
-	r = newLHHostRequest(askerUdp, askerV4, hostV6, lhh)
-	if assert.NotNil(t, r.msg, "BUG: v6 query is silently dropped after a v1 handshake truncated RemoteList.vpnAddrs") {
-		assertIp4InArray(t, r.msg.Details.V4AddrPorts, hostLan)
-	}
-}
-
-// Scenario B: the LH first creates a RemoteList for the host keyed only by its v4 addr (a pending
-// LH-initiated v1 handshake does QueryCache([v4]) in handleOutbound), then the host arrives with v2.
-// unlockedGetRemoteList/QueryCache hit on allAddrs[0] and never add the v6 key to addrMap.
-func TestLighthouse_Issue1868_V4OnlyListNeverGainsV6Key(t *testing.T) {
-	lh, lhh := newIssue1868Lighthouse(t)
-
-	hostV4 := netip.MustParseAddr("10.128.0.3")
-	hostV6 := netip.MustParseAddr("fd00::3")
-	hostUdp := netip.MustParseAddrPort("192.0.2.3:4242")
-	hostLan := netip.MustParseAddrPort("10.0.0.3:4242")
-
-	askerV4 := netip.MustParseAddr("10.128.0.2")
-	askerUdp := netip.MustParseAddrPort("192.0.2.2:4242")
-
-	// LH is a relay and someone asked it to relay to hostV4 while the host was offline:
-	// StartHandshake(hostV4) -> handleOutbound -> QueryCache([hostV4]) creates a v4-only list.
-	_ = lh.QueryCache([]netip.Addr{hostV4})
-
-	// Host boots and handshakes v2 with the LH (responder path does QueryCache + RefreshFromHandshake)
-	rl := lh.QueryCache([]netip.Addr{hostV4, hostV6})
-	rl.RefreshFromHandshake([]netip.Addr{hostV4, hostV6}, cert.Version2)
-	newLHHostUpdateV2(hostUdp, []netip.Addr{hostV4, hostV6}, []netip.AddrPort{hostLan}, lhh)
-
-	r := newLHHostRequest(askerUdp, askerV4, hostV4, lhh)
-	require.NotNil(t, r.msg, "v4 query should be answered")
-	assertIp4InArray(t, r.msg.Details.V4AddrPorts, hostLan)
-
-	r = newLHHostRequest(askerUdp, askerV4, hostV6, lhh)
-	if assert.NotNil(t, r.msg, "BUG: v6 query is silently dropped, addrMap never got the v6 key") {
-		assertIp4InArray(t, r.msg.Details.V4AddrPorts, hostLan)
-	}
-}
@@ -6,14 +6,11 @@ import (
 	"log/slog"
 	"net"
 	"net/netip"
-	"os"
 	"runtime/debug"
-	"slices"
 	"strings"
 	"time"

 	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/cpupick"
 	"github.com/slackhq/nebula/noiseutil"
 	"github.com/slackhq/nebula/overlay"
 	"github.com/slackhq/nebula/sshd"
@@ -43,9 +40,6 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 		buildVersion = moduleVersion()
 	}

-	// Debug builds (-tags debug) serve pprof on :6060; a no-op otherwise.
-	startPprofServer(ctx, l)
-
 	// Print the config if in test, the exit comes later
 	if configTest {
 		b, err := yaml.Marshal(c.Settings)
@@ -176,21 +170,8 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 		}

 		for i := 0; i < routines; i++ {
-			listen := netip.AddrPortFrom(listenHost, uint16(port))
-			l.Info("listening", "addr", listen)
-			batchSize := c.GetInt("listen.batch", 64)
-			if batchSize < 1 {
-				oldBatch := batchSize
-				batchSize = 1
-				l.Warn("listen.batch size is invalid", "provided", oldBatch, "overridden to", batchSize)
-			}
-			udpSettings := udp.Settings{
-				Listen:   listen,
-				Multi:    routines > 1,
-				Batch:    batchSize,
-				Offloads: c.GetBool("listen.udp_offloads", false),
-			}
-			udpServer, err := udp.NewListener(l, udpSettings)
+			l.Info("listening", "addr", netip.AddrPortFrom(listenHost, uint16(port)))
+			udpServer, err := udp.NewListener(l, listenHost, port, routines > 1, c.GetInt("listen.batch", 64))
 			if err != nil {
 				return nil, util.NewContextualError("Failed to open udp listener", m{"queue": i}, err)
 			}
@@ -239,37 +220,6 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 		l.Warn("Failed to start DNS responder", "error", err)
 	}

-	pinThreads := c.GetBool("tun.pin_threads", true)
-	cpuAffinity := parseCpuAffinity(c, l, routines)
-	if pinThreads && routines > 1 && len(cpuAffinity) == 0 && !configTest {
-		// The operator didn't choose pin CPUs, so pick a default set that
-		// prefers performance cores and doesn't stack co-located instances
-		// onto allowed[0].
-
-		// key is used to seed the spreading of routines->cores.
-		// use PID if you want to ensure many different Nebulas in VMs or containers land on different cores
-		// use port if you want to always end up on the same cores, ideal for benchmarking.
-		key := uint64(os.Getpid()) //default to PID
-		pinKeyStr := strings.ToLower(c.GetString("tun.pin_threads_key", ""))
-		switch pinKeyStr {
-		case "":
-			l.Debug("tun.pin_threads_key is empty, using PID")
-		case "pid":
-			l.Debug("tun.pin_threads_key is PID")
-		case "port":
-			if ap, err := udpConns[0].LocalAddr(); err == nil && ap.Port() != 0 {
-				l.Info("tun.pin_threads_key is port number")
-				key = uint64(ap.Port())
-			} else {
-				l.Warn("Failed to get a port number for tun.pin_threads_key, falling back to PID", "err", err)
-			}
-		default:
-			l.Warn("tun.pin_threads_key is invalid, using PID")
-		}
-
-		cpuAffinity = cpupick.Default(routines, key, l)
-	}
-
 	ifConfig := &InterfaceConfig{
 		HostMap:               hostMap,
 		Inside:                tun,
@@ -291,8 +241,6 @@ func Main(c *config.C, configTest bool, buildVersion string, l *slog.Logger, dev
 		relayManager:          NewRelayManager(ctx, l, hostMap, c),
 		punchy:                punchy,
 		ConntrackCacheTimeout: conntrackCacheTimeout,
-		CpuAffinity:           cpuAffinity,
-		PinThreads:            pinThreads,
 		l:                     l,
 	}

@@ -347,70 +295,6 @@ 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 spreading queues across the allowed CPU set).
-// 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, or a CPU ID we're not allowed to run on) are also a
-// warning and disable the override entirely so we don't silently pin to the
-// wrong CPU. Entries are validated against the process's current affinity
-// mask (util.AllowedCPUs) rather than 0..NumCPU-1: under a cgroup cpuset or
-// taskset the runnable IDs are frequently not that contiguous range, and
-// pinning to an unrunnable ID always fails. If the allowed set can't be
-// determined we fall back to a plain non-negative check.
-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
-	}
-	// allowed is the set of CPU IDs we're actually permitted to run on. A nil
-	// slice (unsupported platform or lookup error) means "can't tell", so we
-	// only apply the weaker non-negative check in that case.
-	allowed, err := util.AllowedCPUs()
-	if err != nil {
-		l.Warn("could not determine allowed CPUs; validating tun.cpu_affinity against non-negative only", "error", err)
-		allowed = nil
-	}
-	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 {
-			l.Warn("tun.cpu_affinity entry out of range; ignoring affinity",
-				"index", i, "cpu", cpu)
-			return nil
-		}
-		if len(allowed) > 0 && !slices.Contains(allowed, cpu) {
-			l.Warn("tun.cpu_affinity entry not in allowed CPU set; ignoring affinity",
-				"index", i, "cpu", cpu, "allowed", allowed)
-			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 {
@@ -1,51 +0,0 @@
-package nebula
-
-import (
-	"testing"
-
-	"github.com/slackhq/nebula/config"
-	"github.com/slackhq/nebula/test"
-	"github.com/slackhq/nebula/util"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestParseCpuAffinity(t *testing.T) {
-	l := test.NewLogger()
-
-	// newConfig returns a config.C with tun.cpu_affinity set to v. A nil v
-	// leaves the key unset.
-	newConfig := func(v any) *config.C {
-		c := config.NewC(l)
-		if v != nil {
-			c.Settings["tun"] = map[string]any{"cpu_affinity": v}
-		}
-		return c
-	}
-
-	// unset -> nil (listenIn falls back to spreading across the allowed set)
-	assert.Nil(t, parseCpuAffinity(newConfig(nil), l, 1))
-
-	// Pick a CPU we're actually allowed to run on so a valid list survives
-	// validation regardless of the host's affinity mask.
-	allowed, _ := util.AllowedCPUs()
-	validCPU := 0
-	if len(allowed) > 0 {
-		validCPU = allowed[0]
-	}
-
-	// valid list -> parsed through unchanged
-	assert.Equal(t, []int{validCPU, validCPU}, parseCpuAffinity(newConfig([]any{validCPU, validCPU}), l, 2))
-
-	// a negative entry is out of range on every platform -> disables the override
-	assert.Nil(t, parseCpuAffinity(newConfig([]any{validCPU, -1}), l, 2))
-
-	// a non-integer entry -> disables the override
-	assert.Nil(t, parseCpuAffinity(newConfig([]any{validCPU, "not-a-cpu"}), l, 2))
-
-	// a CPU id outside the allowed set -> disables the override. Only assertable
-	// where we can enumerate the allowed set (e.g. linux); 1<<20 is far beyond
-	// any representable CPU id so it can never be in the mask.
-	if len(allowed) > 0 {
-		assert.Nil(t, parseCpuAffinity(newConfig([]any{1 << 20}), l, 1))
-	}
-}
@@ -4,16 +4,77 @@
 package noiseutil

 import (
-	"crypto/boring"
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/binary"
+
+	// unsafe needed for go:linkname
+	_ "unsafe"

 	"github.com/flynn/noise"
 )

-var CipherAESGCM noise.CipherFunc = CipherAESGCMFIPS140
-
 // EncryptLockNeeded indicates if calls to Encrypt need a lock
 // This is true for boringcrypto because the Seal function verifies that the
 // nonce is strictly increasing.
 const EncryptLockNeeded = true

-var boringEnabled = boring.Enabled()
+// NewGCMTLS is no longer exposed in go1.19+, so we need to link it in
+// See: https://github.com/golang/go/issues/56326
+//
+// NewGCMTLS is the internal method used with boringcrypto that provides a
+// validated mode of AES-GCM which enforces the nonce is strictly
+// monotonically increasing.  This is the TLS 1.2 specification for nonce
+// generation (which also matches the method used by the Noise Protocol)
+//
+// - https://github.com/golang/go/blob/go1.19/src/crypto/tls/cipher_suites.go#L520-L522
+// - https://github.com/golang/go/blob/go1.19/src/crypto/internal/boring/aes.go#L235-L237
+// - https://github.com/golang/go/blob/go1.19/src/crypto/internal/boring/aes.go#L250
+// - https://github.com/google/boringssl/blob/ae223d6138807a13006342edfeef32e813246b39/include/openssl/aead.h#L379-L381
+// - https://github.com/google/boringssl/blob/ae223d6138807a13006342edfeef32e813246b39/crypto/fipsmodule/cipher/e_aes.c#L1082-L1093
+//
+//go:linkname newGCMTLS crypto/internal/boring.NewGCMTLS
+func newGCMTLS(c cipher.Block) (cipher.AEAD, error)
+
+type cipherFn struct {
+	fn   func([32]byte) noise.Cipher
+	name string
+}
+
+func (c cipherFn) Cipher(k [32]byte) noise.Cipher { return c.fn(k) }
+func (c cipherFn) CipherName() string             { return c.name }
+
+// CipherAESGCM is the AES256-GCM AEAD cipher (using NewGCMTLS when GoBoring is present)
+var CipherAESGCM noise.CipherFunc = cipherFn{cipherAESGCMBoring, "AESGCM"}
+
+func cipherAESGCMBoring(k [32]byte) noise.Cipher {
+	c, err := aes.NewCipher(k[:])
+	if err != nil {
+		panic(err)
+	}
+	gcm, err := newGCMTLS(c)
+	if err != nil {
+		panic(err)
+	}
+	return aeadCipher{
+		gcm,
+		func(n uint64) []byte {
+			var nonce [12]byte
+			binary.BigEndian.PutUint64(nonce[4:], n)
+			return nonce[:]
+		},
+	}
+}
+
+type aeadCipher struct {
+	cipher.AEAD
+	nonce func(uint64) []byte
+}
+
+func (c aeadCipher) Encrypt(out []byte, n uint64, ad, plaintext []byte) []byte {
+	return c.Seal(out, c.nonce(n), plaintext, ad)
+}
+
+func (c aeadCipher) Decrypt(out []byte, n uint64, ad, ciphertext []byte) ([]byte, error) {
+	return c.Open(out, c.nonce(n), ciphertext, ad)
+}
@@ -4,6 +4,8 @@
 package noiseutil

 import (
+	"crypto/boring"
+	"encoding/hex"
 	"testing"

 	"github.com/stretchr/testify/assert"
@@ -12,3 +14,33 @@ import (
 func TestEncryptLockNeeded(t *testing.T) {
 	assert.True(t, EncryptLockNeeded)
 }
+
+// Ensure NewGCMTLS validates the nonce is non-repeating
+func TestNewGCMTLS(t *testing.T) {
+	assert.True(t, boring.Enabled())
+
+	// Test Case 16 from GCM Spec:
+	//  - (now dead link): http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/gcm-spec.pdf
+	//  - as listed in boringssl tests: https://github.com/google/boringssl/blob/fips-20220613/crypto/cipher_extra/test/cipher_tests.txt#L412-L418
+	key, _ := hex.DecodeString("feffe9928665731c6d6a8f9467308308feffe9928665731c6d6a8f9467308308")
+	iv, _ := hex.DecodeString("cafebabefacedbaddecaf888")
+	plaintext, _ := hex.DecodeString("d9313225f88406e5a55909c5aff5269a86a7a9531534f7da2e4c303d8a318a721c3c0c95956809532fcf0e2449a6b525b16aedf5aa0de657ba637b39")
+	aad, _ := hex.DecodeString("feedfacedeadbeeffeedfacedeadbeefabaddad2")
+	expected, _ := hex.DecodeString("522dc1f099567d07f47f37a32a84427d643a8cdcbfe5c0c97598a2bd2555d1aa8cb08e48590dbb3da7b08b1056828838c5f61e6393ba7a0abcc9f662")
+	expectedTag, _ := hex.DecodeString("76fc6ece0f4e1768cddf8853bb2d551b")
+
+	expected = append(expected, expectedTag...)
+
+	var keyArray [32]byte
+	copy(keyArray[:], key)
+	c := CipherAESGCM.Cipher(keyArray)
+	aead := c.(aeadCipher).AEAD
+
+	dst := aead.Seal([]byte{}, iv, plaintext, aad)
+	assert.Equal(t, expected, dst)
+
+	// We expect this to fail since we are re-encrypting with a repeat IV
+	assert.PanicsWithError(t, "boringcrypto: EVP_AEAD_CTX_seal failed", func() {
+		dst = aead.Seal([]byte{}, iv, plaintext, aad)
+	})
+}
@@ -40,11 +40,8 @@ type CipherState interface {
 // 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 {
-	if cs, ok := s.Cipher().(CipherState); ok {
-		return cs
-	}
 	switch cipherFunc.CipherName() {
-	case noise.CipherAESGCM.CipherName():
+	case CipherAESGCM.CipherName():
 		return NewCipherStateAESGCM(s)
 	case noise.CipherChaChaPoly.CipherName():
 		return NewCipherStateChaChaPoly(s)
@@ -1,7 +1,6 @@
 package noiseutil

 import (
-	"crypto/fips140"
 	"math"
 	"testing"

@@ -12,30 +11,24 @@ import (

 func TestCipherStateAESGCMRoundtrip(t *testing.T) {
 	enc, dec := buildCipherStates(t, CipherAESGCM)
-	roundtrip(t, NewCipherState(enc, CipherAESGCM), NewCipherState(dec, CipherAESGCM))
+	roundtrip(t, NewCipherStateAESGCM(enc), NewCipherStateAESGCM(dec))
 }

 func TestCipherStateChaChaPolyRoundtrip(t *testing.T) {
 	enc, dec := buildCipherStates(t, noise.CipherChaChaPoly)
-	roundtrip(t, NewCipherState(enc, noise.CipherChaChaPoly), NewCipherState(dec, noise.CipherChaChaPoly))
+	roundtrip(t, NewCipherStateChaChaPoly(enc), NewCipherStateChaChaPoly(dec))
 }

 func TestNewCipherStateDispatch(t *testing.T) {
 	encA, _ := buildCipherStates(t, CipherAESGCM)
 	encC, _ := buildCipherStates(t, noise.CipherChaChaPoly)

-	if !boringEnabled && !fips140.Enabled() {
-		assert.IsType(t, &CipherStateAESGCM{}, NewCipherState(encA, CipherAESGCM))
-	} else {
-		// fips140
-		assert.IsType(t, encA.Cipher(), NewCipherState(encA, CipherAESGCM))
-	}
-
+	assert.IsType(t, &CipherStateAESGCM{}, NewCipherState(encA, CipherAESGCM))
 	assert.IsType(t, &CipherStateChaChaPoly{}, NewCipherState(encC, noise.CipherChaChaPoly))
 }

 func TestNewCipherStateUnsupportedPanics(t *testing.T) {
-	enc, _ := buildCipherStates(t, noise.CipherChaChaPoly)
+	enc, _ := buildCipherStates(t, CipherAESGCM)
 	assert.Panics(t, func() {
 		NewCipherState(enc, fakeCipher{})
 	})
@@ -190,48 +183,3 @@ func TestCipherStateNilSafety(t *testing.T) {
 	assert.Empty(t, out)
 	assert.Equal(t, 0, cc.Overhead())
 }
-
-func TestCipherStateAESGCMInPlaceDecrypt(t *testing.T) {
-	enc, dec := buildCipherStates(t, CipherAESGCM)
-	inPlaceDecrypt(t, NewCipherStateAESGCM(enc), NewCipherStateAESGCM(dec))
-}
-
-func TestCipherStateChaChaPolyInPlaceDecrypt(t *testing.T) {
-	enc, dec := buildCipherStates(t, noise.CipherChaChaPoly)
-	inPlaceDecrypt(t, NewCipherStateChaChaPoly(enc), NewCipherStateChaChaPoly(dec))
-}
-
-func inPlaceDecrypt(t *testing.T, enc, dec CipherState) {
-	t.Helper()
-	const hdrLen = 16
-	plaintext := []byte("in-place decrypt should replace the ciphertext bytes")
-	nb := make([]byte, 12)
-
-	// packet = [16-byte header | ciphertext+tag], like a nebula Message.
-	packet := make([]byte, hdrLen, hdrLen+len(plaintext)+enc.Overhead())
-	for i := range packet {
-		packet[i] = byte(i)
-	}
-	packet, err := enc.EncryptDanger(packet, packet[:hdrLen], plaintext, 1, nb)
-	require.NoError(t, err)
-
-	// Simulate a GRO row: [packet | next segment]. A failed auth on packet
-	// may zero packet's plaintext region but must not touch the header, the
-	// tag, or the neighboring segment.
-	neighbor := []byte("next coalesced segment, must stay intact")
-	row := append(append([]byte(nil), packet...), neighbor...)
-	tampered := row[:len(packet)]
-	tampered[hdrLen] ^= 0x01
-	_, err = dec.DecryptDanger(tampered[hdrLen:hdrLen], tampered[:hdrLen], tampered[hdrLen:], 1, nb)
-	require.Error(t, err)
-	assert.Equal(t, packet[:hdrLen], tampered[:hdrLen], "failed auth must not touch the header")
-	assert.Equal(t, packet[len(packet)-dec.Overhead():], tampered[len(tampered)-dec.Overhead():],
-		"failed auth must not touch the tag")
-	assert.Equal(t, neighbor, row[len(packet):], "failed auth must not touch the next segment")
-
-	out, err := dec.DecryptDanger(packet[hdrLen:hdrLen], packet[:hdrLen], packet[hdrLen:], 1, nb)
-	require.NoError(t, err)
-	assert.Equal(t, plaintext, out)
-	// The plaintext must be IN the packet buffer, not a fresh allocation.
-	assert.Equal(t, &packet[hdrLen], &out[0], "plaintext must alias the packet buffer")
-}
@@ -1,197 +0,0 @@
-package noiseutil
-
-import (
-	"bytes"
-	"crypto/cipher"
-	"crypto/fips140"
-	"encoding/binary"
-	"errors"
-	"fmt"
-	"reflect"
-	"runtime"
-	"unsafe"
-
-	// unsafe needed for go:linkname
-	_ "crypto/tls"
-	_ "unsafe"
-
-	"github.com/flynn/noise"
-)
-
-// TODO: Use NewGCMWithCounterNonce or NewGCMForQUIC once available:
-// - https://github.com/golang/go/issues/73110
-// - https://github.com/golang/go/issues/79219
-// Using tls.aeadAESGCMTLS13 gives us the TLS 1.3 GCM, which also verifies
-// that the nonce is strictly increasing. This works for both boringcrypto
-// and fips140.
-//
-//go:linkname aeadAESGCMTLS13 crypto/tls.aeadAESGCMTLS13
-func aeadAESGCMTLS13(key, noncePrefix []byte) cipher.AEAD
-
-type cipherFn struct {
-	fn   func([32]byte) noise.Cipher
-	name string
-}
-
-func (c cipherFn) Cipher(k [32]byte) noise.Cipher { return c.fn(k) }
-func (c cipherFn) CipherName() string             { return c.name }
-
-// CipherAESGCMFIPS140 is the AES256-GCM AEAD cipher (using tls.aeadAESGCMTLS13, for both boringcrypto and fips140)
-var CipherAESGCMFIPS140 noise.CipherFunc = cipherFn{cipherAESGCMFIPS140, "AESGCM"}
-
-// tls.aeadAESGCMTLS13 uses a 4 byte static prefix and an 8 byte XOR mask
-var emptyNonce = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
-
-func cipherAESGCMFIPS140(k [32]byte) noise.Cipher {
-	gcm := aeadAESGCMTLS13(k[:], emptyNonce)
-	gcm = extractFIPSAEAD(gcm)
-	return &aeadGCMFIPS140Cipher{
-		AEAD: gcm,
-	}
-}
-
-type aeadGCMFIPS140Cipher struct {
-	cipher.AEAD
-	ready bool
-}
-
-// Extract the internal FIPS GCM implementation from the tls wrapper. The TLS
-// wrapper is not thread safe around Open, so instead of locking around it we
-// can grab the internal implementation that is thread safe. This is the FIPS
-// module implementation: `crypto/internal/fips140/aes/gcm.GCMWithXORCounterNonce`
-//
-// - https://github.com/golang/go/blob/go1.26.4/src/crypto/internal/fips140/aes/gcm/gcm_nonces.go#L212-L287
-//
-// The wrapper is struct `crypto/tls.xorNonceAEAD` , with field `aead`:
-//
-// - https://github.com/golang/go/blob/go1.26.4/src/crypto/tls/cipher_suites.go#L482-L487
-//
-// This can be cleaned up once these FIPS implementations are exposed directly:
-//
-// - https://github.com/golang/go/issues/73110
-func extractFIPSAEAD(xorNonceAEAD cipher.AEAD) cipher.AEAD {
-	r := reflect.ValueOf(xorNonceAEAD)
-	v := r.Elem().FieldByName("aead")
-	if !v.IsValid() {
-		// The internal crypto/tls.xorNonceAEAD struct no longer has an `aead`
-		// field. This can only happen on a Go version this code was not built
-		// against; the package init() self-test guards against ever reaching
-		// this at runtime, so this is a defensive fail-fast.
-		panic(fmt.Sprintf("noiseutil: could not extract FIPS AEAD from %T on %s: no `aead` field (incompatible Go version)", xorNonceAEAD, runtime.Version()))
-	}
-	v2 := reflect.NewAt(v.Type(), unsafe.Pointer(v.UnsafeAddr())).Elem()
-	aead, ok := v2.Interface().(cipher.AEAD)
-	if !ok {
-		panic(fmt.Sprintf("noiseutil: extracted FIPS `aead` field is %s, not a cipher.AEAD, on %s (incompatible Go version)", v2.Type(), runtime.Version()))
-	}
-	return aead
-}
-
-func (c *aeadGCMFIPS140Cipher) init(nonce []byte) {
-	// GCMWithXORCounterNonce expects that the first call to Seal
-	// is with a counter of `0`, this is how it extracts the nonce mask.
-	// We can clean this up in the future when NewGCMWithCounterNonce or
-	// NewGCMForQUIC are available:
-	if !bytes.Equal(emptyNonce, nonce) {
-		c.AEAD.Seal([]byte{}, emptyNonce, []byte{}, []byte{})
-	}
-	c.ready = true
-}
-
-func (c *aeadGCMFIPS140Cipher) Seal(dst, nonce, plaintext, additionalData []byte) []byte {
-	if !c.ready {
-		c.init(nonce)
-	}
-	return c.AEAD.Seal(dst, nonce, plaintext, additionalData)
-}
-
-func (c *aeadGCMFIPS140Cipher) Encrypt(out []byte, n uint64, ad, plaintext []byte) []byte {
-	return c.Seal(out, aeadGCMFIPS140CipherNonce(n), plaintext, ad)
-}
-
-func (c *aeadGCMFIPS140Cipher) Decrypt(out []byte, n uint64, ad, ciphertext []byte) ([]byte, error) {
-	return c.Open(out, aeadGCMFIPS140CipherNonce(n), ciphertext, ad)
-}
-
-func (c *aeadGCMFIPS140Cipher) EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error) {
-	if c == nil {
-		return nil, errors.New("no cipher state available to encrypt")
-	}
-	if n >= RejectAfterMessages {
-		return nil, ErrMessageCounterExhausted
-	}
-	binary.BigEndian.PutUint64(nb[4:], n)
-	out = c.Seal(out, nb, plaintext, ad)
-	return out, nil
-}
-
-func (c *aeadGCMFIPS140Cipher) DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error) {
-	if c == nil {
-		return []byte{}, nil
-	}
-	binary.BigEndian.PutUint64(nb[4:], n)
-	return c.Open(out, nb, ciphertext, ad)
-}
-
-func (c *aeadGCMFIPS140Cipher) Overhead() int {
-	if c == nil {
-		return 0
-	}
-	return c.AEAD.Overhead()
-}
-
-func aeadGCMFIPS140CipherNonce(n uint64) []byte {
-	// GCMWithXORCounterNonce uses a 4 byte static prefix and an 8 byte nonce
-	var nonce [12]byte
-	binary.BigEndian.PutUint64(nonce[4:], n)
-	return nonce[:]
-}
-
-func init() {
-	if boringEnabled || fips140.Enabled() {
-		initSelfTestAESGCMFIPS140()
-	}
-}
-
-// validates the go:linkname + reflection extraction and the nonce-reuse
-// protection at startup. cipherAESGCMFIPS140 relies on unexported
-// crypto/tls and crypto/internal/fips140 internals; if a future Go version changes
-// those, this fails fast with a clear message instead of panicking per-handshake
-// (or, worse, silently losing the strictly-increasing nonce check that is the whole
-// point of using this cipher).
-func initSelfTestAESGCMFIPS140() {
-	var key [32]byte
-	c := cipherAESGCMFIPS140(key)
-
-	// Verify the extracted AEAD produces a working encrypt/decrypt roundtrip.
-	plaintext := []byte("nebula fips140 self-test")
-	ad := []byte("ad")
-	ct := c.Encrypt(nil, 1, ad, plaintext)
-	pt, err := c.Decrypt(nil, 1, ad, ct)
-	if err != nil {
-		panic(fmt.Sprintf("noiseutil: FIPS AES-GCM self-test roundtrip failed on %s: %v", runtime.Version(), err))
-	}
-	if !bytes.Equal(pt, plaintext) {
-		panic(fmt.Sprintf("noiseutil: FIPS AES-GCM self-test roundtrip returned wrong plaintext on %s", runtime.Version()))
-	}
-
-	// Verify the nonce-reuse protection still fires: re-encrypting with the same
-	// counter must panic. This is the defensive check that FIPS-140 requires, so
-	// if the extraction ever silently yields an AEAD without it, refuse to start.
-	if !reusePanics(c) {
-		panic(fmt.Sprintf("noiseutil: FIPS AES-GCM self-test did not reject a reused nonce on %s; nonce-reuse protection is missing (incompatible Go version)", runtime.Version()))
-	}
-}
-
-// reusePanics reports whether re-encrypting with an already-used counter panics,
-// as GCMWithXORCounterNonce is expected to.
-func reusePanics(c noise.Cipher) (panicked bool) {
-	c.Encrypt(nil, 2, nil, nil)
-	defer func() {
-		if recover() != nil {
-			panicked = true
-		}
-	}()
-	c.Encrypt(nil, 2, nil, nil)
-	return false
-}
@@ -1,48 +0,0 @@
-package noiseutil
-
-import (
-	"crypto/cipher"
-	"crypto/fips140"
-	"encoding/hex"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-// Ensure NewAESGCM validates the nonce is non-repeating
-func TestNewAESGCM(t *testing.T) {
-	if !boringEnabled && !fips140.Enabled() {
-		t.Skip("TestNewAESGCM is only for fips140/boringcrypto")
-	}
-
-	key, _ := hex.DecodeString("feffe9928665731c6d6a8f9467308308feffe9928665731c6d6a8f9467308308")
-	iv, _ := hex.DecodeString("00000000facedbaddecaf888")
-	plaintext, _ := hex.DecodeString("d9313225f88406e5a55909c5aff5269a86a7a9531534f7da2e4c303d8a318a721c3c0c95956809532fcf0e2449a6b525b16aedf5aa0de657ba637b39")
-	aad, _ := hex.DecodeString("feedfacedeadbeeffeedfacedeadbeefabaddad2")
-	expected, _ := hex.DecodeString("6a65c2edd45bd63c7e29f40e3d2ed8ba2b99f4c83135383d5676652f255059ceb24863ff10afb1089db701245da87fb88d3acd5f9dd0770cac220c3c04145caf25e190aeb775e7080401c628")
-
-	var keyArray [32]byte
-	copy(keyArray[:], key)
-	c := CipherAESGCM.Cipher(keyArray)
-	aead := c.(cipher.AEAD)
-
-	dst := aead.Seal([]byte{}, iv, plaintext, aad)
-	t.Logf("%x", dst)
-	assert.Equal(t, expected, dst)
-
-	// We expect this to fail since we are re-encrypting with a repeat IV
-	switch {
-	case boringEnabled:
-		assert.PanicsWithError(t, "boringcrypto: EVP_AEAD_CTX_seal failed", func() {
-			dst = aead.Seal([]byte{}, iv, plaintext, aad)
-		})
-	case fips140.Version() == "v1.0.0":
-		assert.PanicsWithValue(t, "crypto/cipher: counter decreased", func() {
-			dst = aead.Seal([]byte{}, iv, plaintext, aad)
-		})
-	default:
-		assert.PanicsWithValue(t, "crypto/cipher: counter decreased or remained the same", func() {
-			dst = aead.Seal([]byte{}, iv, plaintext, aad)
-		})
-	}
-}
@@ -1,13 +0,0 @@
-//go:build fips140enforce
-
-package noiseutil
-
-import (
-	"crypto/fips140"
-)
-
-func init() {
-	if !fips140.Enforced() {
-		panic("Nebula compiled with fips140 expects FIPS140 to be enforced. Do not set GODEBUG=fips140, or if you do it must be set as GODEBUG=fips140=only")
-	}
-}
@@ -1,25 +1,14 @@
 //go:build !boringcrypto
+// +build !boringcrypto

 package noiseutil

 import (
-	"crypto/fips140"
-
 	"github.com/flynn/noise"
 )

 // EncryptLockNeeded indicates if calls to Encrypt need a lock
-var EncryptLockNeeded = fips140.Enabled()
+const EncryptLockNeeded = false

-var CipherAESGCM noise.CipherFunc = initAESGCM()
-
-func initAESGCM() noise.CipherFunc {
-	if fips140.Enabled() {
-		return CipherAESGCMFIPS140
-	} else {
-		return noise.CipherAESGCM
-	}
-
-}
-
-var boringEnabled = false
+// CipherAESGCM is the standard noise.CipherAESGCM when boringcrypto is not enabled
+var CipherAESGCM noise.CipherFunc = noise.CipherAESGCM
@@ -0,0 +1,14 @@
+//go:build !boringcrypto
+// +build !boringcrypto
+
+package noiseutil
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestEncryptLockNeeded(t *testing.T) {
+	assert.False(t, EncryptLockNeeded)
+}
@@ -8,12 +8,12 @@ import (
 	"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/iputil"
-	"github.com/slackhq/nebula/overlay/batch"
 	"golang.org/x/net/ipv4"
 )

@@ -23,11 +23,7 @@ const (

 var ErrOutOfWindow = errors.New("out of window packet")

-// readOutsidePackets processes one received underlay packet.
-// Message payloads are decrypted IN PLACE, so packet must stay untouched
-// by the caller until the batcher for queue q has been flushed
-func (f *Interface) readOutsidePackets(via ViaSender, packet []byte, rxc *rxContext) {
-	h := rxc.h
+func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
 	err := h.Parse(packet)
 	if err != nil {
 		// Hole punch packets are 0 or 1 byte big, so lets ignore printing those errors
@@ -95,7 +91,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, packet []byte, rxc *rxCont
 	if isMessageRelay {
 		hostinfo = f.hostMap.QueryRelayIndex(h.RemoteIndex)
 	} else {
-		hostinfo = f.hostMap.QueryIndexCached(h.RemoteIndex, rxc.hostmapCache)
+		hostinfo = f.hostMap.QueryIndex(h.RemoteIndex)
 	}

 	// At this point we should have a valid existing tunnel, verify and send
@@ -118,18 +114,17 @@ func (f *Interface) readOutsidePackets(via ViaSender, packet []byte, rxc *rxCont
 	// All remaining packets are encrypted
 	if isMessageRelay {
 		// Relay packets are special, this branch should always early-return
-		err = hostinfo.ConnectionState.VerifyRelay(f.l, h.MessageCounter, packet, rxc.nb)
-		if err != nil {
+		if err = hostinfo.ConnectionState.VerifyRelay(f.l, h.MessageCounter, packet, nb); err != nil {
 			if f.l.Enabled(context.Background(), slog.LevelDebug) {
 				hostinfo.logger(f.l).Debug("Failed to verify relay packet", "error", err, "from", via, "header", h)
 			}
 			return
 		}
-		f.handleOutsideRelayPacket(hostinfo, via, packet, rxc)
+		f.handleOutsideRelayPacket(hostinfo, via, out, packet, h, fwPacket, lhf, nb, q, localCache)
 		return
 	}

-	out, err := hostinfo.ConnectionState.Decrypt(f.l, h.MessageCounter, packet, rxc.nb)
+	out, err = hostinfo.ConnectionState.Decrypt(f.l, h.MessageCounter, out, packet, 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)
@@ -145,7 +140,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, packet []byte, rxc *rxCont
 	case header.Message:
 		switch h.Subtype {
 		case header.MessageNone:
-			f.handleOutsideMessagePacket(hostinfo, h.MessageCounter, out, rxc)
+			f.handleOutsideMessagePacket(hostinfo, out, packet, fwPacket, nb, q, localCache)
 		default:
 			hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected message subtype seen", "from", via, "header", h)
 			return
@@ -153,23 +148,15 @@ func (f *Interface) readOutsidePackets(via ViaSender, packet []byte, rxc *rxCont

 	case header.LightHouse:
 		//TODO: assert via is not relayed
-		rxc.lhh.HandleRequest(via.UdpAddr, hostinfo.vpnAddrs, out, f)
+		lhf.HandleRequest(via.UdpAddr, hostinfo.vpnAddrs, out, f)

 	case header.Test:
 		switch h.Subtype {
 		case header.TestReply:
 			// No-op, useful for the Roaming and connectionManager side-effects above
 		case header.TestRequest:
-			const maxCipherOverhead = 16 //todo we use this too often, needs a real importable const
-			const maxOverhead = header.Len + header.Len + maxCipherOverhead + maxCipherOverhead
-			if maxOverhead+len(out) > len(rxc.scratch) {
-				// A reply that cannot fit in scratch is dropped no matter the log level.
-				if f.l.Enabled(context.Background(), slog.LevelDebug) {
-					hostinfo.logger(f.l).Debug("dropping oversized test request", "payloadLen", len(out), "from", via)
-				}
-				return
-			}
-			f.send(header.Test, header.TestReply, hostinfo.ConnectionState, hostinfo, out, rxc.nb, rxc.scratch[:0])
+			//recycle the input packet ciphertext as our output buffer
+			f.send(header.Test, header.TestReply, hostinfo.ConnectionState, hostinfo, out, nb, packet)
 		default:
 			hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected test subtype seen", "from", via, "header", h)
 			return
@@ -187,8 +174,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, packet []byte, rxc *rxCont
 	}
 }

-func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, packet []byte, rxc *rxContext) {
-	h := rxc.h
+func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
 	// Successfully validated the thing. Get rid of the Relay header and the AEAD tag
 	signedPayload := packet[header.Len : len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
 	// Pull the Roaming parts up here, and return in all call paths.
@@ -201,7 +187,9 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
 	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", "relayRemoteIndex", h.RemoteIndex)
+		hostinfo.logger(f.l).Error("HostInfo missing remote relay index",
+			"relayRemoteIndex", h.RemoteIndex,
+		)
 		return
 	}

@@ -215,7 +203,7 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
 			relay:     relay,
 			IsRelayed: true,
 		}
-		f.readOutsidePackets(via, signedPayload, rxc)
+		f.readOutsidePackets(via, out[:0], signedPayload, h, fwPacket, lhf, nb, q, localCache)
 	case ForwardingType:
 		// Find the target HostInfo relay object
 		targetHI, targetRelay, err := f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relay.PeerAddr)
@@ -234,9 +222,8 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
 			case ForwardingType:
 				// Forward this packet through the relay tunnel, rebuilding it in place.
 				// Encode overwrites the old outer header, and the new AEAD tag lands where the old one was
-				fwdBuf := packet[:0]
-				//todo it would potentially be nice to batch these
-				f.SendVia(targetHI, targetRelay, signedPayload, rxc.nb, fwdBuf, true, rxc.q)
+				fwdBuf := packet[:0:len(packet)] // Cap to len(packet) to protect memory from a larger parent buffer
+				f.SendVia(targetHI, targetRelay, signedPayload, nb, fwdBuf, true)
 			case TerminalType:
 				hostinfo.logger(f.l).Error("Unexpected Relay Type of Terminal")
 				return
@@ -316,11 +303,7 @@ var (
 )

 // newPacket validates and parses the interesting bits for the firewall out of the ip and sub protocol headers
-func newPacket(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
-	// fp is reused across packets; reset the parse byproducts so an early-error return cannot
-	// leak the previous packet's offsets.
-	fp.IPHdrLen = 0
-	fp.FragAny = false
+func newPacket(data []byte, incoming bool, fp *firewall.Packet) error {
 	if len(data) < 1 {
 		return ErrPacketTooShort
 	}
@@ -335,7 +318,7 @@ func newPacket(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	return ErrUnknownIPVersion
 }

-func parseV6(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
+func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
 	dataLen := len(data)
 	if dataLen < ipv6.HeaderLen {
 		return ErrIPv6PacketTooShort
@@ -352,15 +335,13 @@ func parseV6(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	// Walk the extension header chain to the upper layer protocol. iputil.IPv6FindUpperProtocol is the single
 	// source of truth for which headers are extension headers, so this stays in lockstep with the reject path
 	// and cannot drift into misreading an unknown protocol (SCTP, GRE, etc.) as a forged transport.
-	proto, offset, isFragment, anyFragment, err := iputil.IPv6FindUpperProtocol(data)
+	proto, offset, isFragment, err := iputil.IPv6FindUpperProtocol(data)
 	if err != nil {
 		return ErrIPv6PacketTooShort
 	}

 	fp.Protocol = proto
 	fp.Fragment = isFragment
-	fp.FragAny = anyFragment
-	fp.IPHdrLen = offset
 	if isFragment {
 		// Non-first fragments carry no transport header, so we have no ports to read
 		fp.RemotePort = 0
@@ -368,15 +349,15 @@ func parseV6(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 		return nil
 	}

-	switch proto {
-	case iputil.IPProtocolICMPv6:
+	switch layers.IPProtocol(proto) {
+	case layers.IPProtocolICMPv6:
 		// An ICMPv6 message is at least type, code and checksum, 4 bytes. Only echo carries more than we read.
 		if dataLen < offset+4 {
 			return ErrIPv6PacketTooShort
 		}
 		fp.LocalPort = 0      //incoming vs outgoing doesn't matter for icmpv6
 		switch data[offset] { //icmp type
-		case iputil.ICMPv6TypeEchoRequest, iputil.ICMPv6TypeEchoReply:
+		case layers.ICMPv6TypeEchoRequest, layers.ICMPv6TypeEchoReply:
 			if dataLen < offset+6 {
 				return ErrIPv6PacketTooShort
 			}
@@ -385,7 +366,7 @@ func parseV6(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 			fp.RemotePort = 0
 		}

-	case iputil.IPProtocolTCP, iputil.IPProtocolUDP:
+	case layers.IPProtocolTCP, layers.IPProtocolUDP:
 		if dataLen < offset+4 {
 			return ErrIPv6PacketTooShort
 		}
@@ -406,7 +387,7 @@ func parseV6(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	return nil
 }

-func parseV4(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
+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
@@ -423,10 +404,6 @@ func parseV4(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	// 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
-	// Any fragmentation at all (MF or offset): first fragments have readable ports for the
-	// firewall but must never be coalesced.
-	fp.FragAny = (flagsfrags & 0x3fff) != 0
-	fp.IPHdrLen = ihl

 	// Firewall handles protocol checks
 	fp.Protocol = data[9]
@@ -434,7 +411,7 @@ func parseV4(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	// Accounting for a variable header length, do we have enough data for our src/dst tuples?
 	minLen := ihl
 	if !fp.Fragment {
-		if fp.Protocol == iputil.IPProtocolICMP {
+		if fp.Protocol == firewall.ProtoICMP {
 			minLen += minFwPacketLen + 2
 		} else {
 			minLen += minFwPacketLen
@@ -456,7 +433,7 @@ func parseV4(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	if fp.Fragment {
 		fp.RemotePort = 0
 		fp.LocalPort = 0
-	} else if fp.Protocol == iputil.IPProtocolICMP { //note that orientation doesn't matter on ICMP
+	} 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 {
@@ -470,23 +447,31 @@ func parseV4(data []byte, incoming bool, fp *firewall.ParsedPacket) error {
 	return nil
 }

-func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, messageCounter uint64, out []byte, rxc *rxContext) {
-	err := newPacket(out, true, rxc.fwPacket)
+func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, out []byte, packet []byte, fwPacket *firewall.Packet, nb []byte, q int, localCache firewall.ConntrackCache) {
+	err := newPacket(out, true, fwPacket)
 	if err != nil {
-		hostinfo.logger(f.l).Warn("Error while validating inbound packet", "error", err, "packet", out)
+		hostinfo.logger(f.l).Warn("Error while validating inbound packet",
+			"error", err,
+			"packet", out,
+		)
 		return
 	}

-	dropReason := f.firewall.Drop(rxc.fwPacket.Packet, true, hostinfo, f.pki.GetCAPool(), rxc.ctCache.Get())
+	dropReason := f.firewall.Drop(*fwPacket, true, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason != nil {
-		f.rejectOutside(out, hostinfo.ConnectionState, hostinfo, rxc.nb, rxc.scratch, rxc.q)
+		// 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)
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("dropping inbound packet", "fwPacket", rxc.fwPacket, "reason", dropReason)
+			hostinfo.logger(f.l).Debug("dropping inbound packet",
+				"fwPacket", fwPacket,
+				"reason", dropReason,
+			)
 		}
 		return
 	}

-	err = f.batchers[rxc.q].Commit(out, batch.SortKey{Epoch: hostinfo.ConnectionState.epoch, Counter: messageCounter}, rxc.fwPacket)
+	_, err = f.readers[q].Write(out)
 	if err != nil {
 		f.l.Error("Failed to write to tun", "error", err)
 	}
@@ -9,7 +9,6 @@ import (

 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
-	"github.com/slackhq/nebula/iputil"

 	"github.com/slackhq/nebula/firewall"
 	"github.com/stretchr/testify/assert"
@@ -19,7 +18,7 @@ import (
 )

 func Test_newPacket(t *testing.T) {
-	p := &firewall.ParsedPacket{}
+	p := &firewall.Packet{}

 	// length fails
 	err := newPacket([]byte{}, true, p)
@@ -59,7 +58,7 @@ func Test_newPacket(t *testing.T) {
 		Src:      net.IPv4(10, 0, 0, 1),
 		Dst:      net.IPv4(10, 0, 0, 2),
 		Options:  []byte{0, 1, 0, 2},
-		Protocol: iputil.IPProtocolTCP,
+		Protocol: firewall.ProtoTCP,
 	}

 	b, _ = h.Marshal()
@@ -67,7 +66,7 @@ func Test_newPacket(t *testing.T) {
 	err = newPacket(b, true, p)

 	require.NoError(t, err)
-	assert.Equal(t, uint8(iputil.IPProtocolTCP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("10.0.0.2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("10.0.0.1"), p.RemoteAddr)
 	assert.Equal(t, uint16(3), p.RemotePort)
@@ -98,7 +97,7 @@ func Test_newPacket(t *testing.T) {
 }

 func Test_newPacket_v6(t *testing.T) {
-	p := &firewall.ParsedPacket{}
+	p := &firewall.Packet{}

 	// invalid ipv6
 	ip := layers.IPv6{
@@ -240,7 +239,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// A good UDP packet
 	ip = layers.IPv6{
 		Version:    6,
-		NextHeader: iputil.IPProtocolUDP,
+		NextHeader: firewall.ProtoUDP,
 		HopLimit:   128,
 		SrcIP:      net.IPv6linklocalallrouters,
 		DstIP:      net.IPv6linklocalallnodes,
@@ -263,7 +262,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// incoming
 	err = newPacket(b, true, p)
 	require.NoError(t, err)
-	assert.Equal(t, uint8(iputil.IPProtocolUDP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
 	assert.Equal(t, uint16(36123), p.RemotePort)
@@ -273,7 +272,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// outgoing
 	err = newPacket(b, false, p)
 	require.NoError(t, err)
-	assert.Equal(t, uint8(iputil.IPProtocolUDP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.RemoteAddr)
 	assert.Equal(t, uint16(36123), p.LocalPort)
@@ -290,7 +289,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// incoming
 	err = newPacket(b, true, p)
 	require.NoError(t, err)
-	assert.Equal(t, uint8(iputil.IPProtocolTCP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
 	assert.Equal(t, uint16(36123), p.RemotePort)
@@ -300,7 +299,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// outgoing
 	err = newPacket(b, false, p)
 	require.NoError(t, err)
-	assert.Equal(t, uint8(iputil.IPProtocolTCP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.RemoteAddr)
 	assert.Equal(t, uint16(36123), p.LocalPort)
@@ -345,7 +344,7 @@ func Test_newPacket_v6(t *testing.T) {

 	err = newPacket(b, true, p)
 	require.NoError(t, err)
-	assert.Equal(t, uint8(iputil.IPProtocolUDP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
 	assert.Equal(t, uint16(36123), p.RemotePort)
@@ -363,7 +362,7 @@ func Test_newPacket_v6(t *testing.T) {
 }

 func Test_newPacket_ipv6Fragment(t *testing.T) {
-	p := &firewall.ParsedPacket{}
+	p := &firewall.Packet{}

 	ip := &layers.IPv6{
 		Version:    6,
@@ -543,7 +542,7 @@ func BenchmarkParseV6(b *testing.B) {
 	secondFrag = append(secondFrag, fragHeader...)
 	secondFrag = append(secondFrag, []byte{0xde, 0xad, 0xbe, 0xef}...)

-	fp := &firewall.ParsedPacket{}
+	fp := &firewall.Packet{}

 	b.Run("Normal", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
@@ -667,7 +666,7 @@ func serializeAH(ah *layers.IPSecAH) []byte {
 // host OS parses the real header, a firewall port/proto bypass. The fix makes parseV6 land
 // on the same offset the host does.
 func Test_newPacket_v6ExtHeaderOverflow(t *testing.T) {
-	p := &firewall.ParsedPacket{}
+	p := &firewall.Packet{}

 	const (
 		hdrLen      = 40              // IPv6 header
@@ -679,7 +678,7 @@ func Test_newPacket_v6ExtHeaderOverflow(t *testing.T) {
 	pkt := make([]byte, realTCPAt+4)
 	pkt[0] = 0x60                                   // version 6
 	pkt[6] = byte(layers.IPProtocolIPv6Destination) // NextHeader -> Destination Options
-	pkt[40] = byte(iputil.IPProtocolTCP)            // Dest-Options NextHeader -> TCP
+	pkt[40] = byte(firewall.ProtoTCP)               // Dest-Options NextHeader -> TCP
 	pkt[41] = 255                                   // HdrExtLen = 255

 	// Forged transport header at the pre-fix (wrong) offset: dst port 443.
@@ -688,7 +687,7 @@ func Test_newPacket_v6ExtHeaderOverflow(t *testing.T) {
 	binary.BigEndian.PutUint16(pkt[realTCPAt+2:realTCPAt+4], 22)

 	require.NoError(t, newPacket(pkt, true, p))
-	assert.Equal(t, uint8(iputil.IPProtocolTCP), p.Protocol)
+	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	// LocalPort is the destination port for incoming traffic. It must be the real port (22)
 	// the host delivers to, not the forged 443 at the overflowed offset.
 	assert.Equal(t, uint16(22), p.LocalPort, "firewall must parse the real transport header, not the overflowed offset")
@@ -698,7 +697,7 @@ func Test_newPacket_v6ExtHeaderOverflow(t *testing.T) {
 // advances the walk past the end of the packet. The upper layer protocol's header isn't actually present,
 // so parseV6 must drop the packet rather than classify it as the terminal protocol with no ports.
 func Test_newPacket_v6ExtHeaderPastBuffer(t *testing.T) {
-	p := &firewall.ParsedPacket{}
+	p := &firewall.Packet{}

 	pkt := make([]byte, 48)
 	pkt[0] = 0x60
@@ -717,7 +716,7 @@ func Test_newPacket_v6ExtHeaderPastBuffer(t *testing.T) {
 // would trust while the host delivered the real SCTP datagram. The fix fails closed: the packet
 // is classified as its true protocol with no ports, so it only matches an `any` rule.
 func Test_newPacket_v6ExtHeaderConfusion(t *testing.T) {
-	p := &firewall.ParsedPacket{}
+	p := &firewall.Packet{}

 	pkt := make([]byte, 52)
 	pkt[0] = 0x60                        // version 6
@@ -756,88 +755,3 @@ func Test_newPacket_v6ExtHeaderConfusion(t *testing.T) {
 	assert.Equal(t, uint16(0), p.LocalPort)
 	assert.False(t, p.Fragment)
 }
-
-// Test_newPacket_parsedFields pins the ParsedPacket byproducts the RX
-// batcher consumes: IPHdrLen (the true L4 offset) and FragAny (any fragment
-// shape at all — unlike Packet.Fragment, which is port-oriented and true
-// only for non-first fragments).
-func Test_newPacket_parsedFields(t *testing.T) {
-	p := &firewall.ParsedPacket{}
-
-	// Plain IPv4 TCP, IHL 20: L4 offset 20, no fragment shape.
-	v4 := make([]byte, 28)
-	v4[0] = 0x45
-	v4[9] = iputil.IPProtocolTCP
-	binary.BigEndian.PutUint16(v4[6:8], 0x4000) // DF only
-	require.NoError(t, newPacket(v4, true, p))
-	assert.Equal(t, 20, p.IPHdrLen)
-	assert.False(t, p.FragAny)
-	assert.False(t, p.Fragment)
-
-	// IPv4 first fragment (MF set, offset 0): the firewall can read ports
-	// (Fragment false) but the coalescer must not touch it (FragAny true).
-	ff := make([]byte, 28)
-	ff[0] = 0x45
-	ff[9] = iputil.IPProtocolUDP
-	binary.BigEndian.PutUint16(ff[6:8], 0x2000) // MF, offset 0
-	require.NoError(t, newPacket(ff, true, p))
-	assert.False(t, p.Fragment)
-	assert.True(t, p.FragAny)
-	assert.Equal(t, 20, p.IPHdrLen)
-
-	// IPv4 non-first fragment (nonzero offset): both flags set.
-	nf := make([]byte, 28)
-	nf[0] = 0x45
-	nf[9] = iputil.IPProtocolUDP
-	binary.BigEndian.PutUint16(nf[6:8], 0x00b9)
-	require.NoError(t, newPacket(nf, true, p))
-	assert.True(t, p.Fragment)
-	assert.True(t, p.FragAny)
-
-	// IPv4 with options (IHL 24): IPHdrLen tracks the real L4 offset.
-	opts := make([]byte, 32)
-	opts[0] = 0x46
-	opts[9] = iputil.IPProtocolTCP
-	binary.BigEndian.PutUint16(opts[6:8], 0x4000)
-	require.NoError(t, newPacket(opts, true, p))
-	assert.Equal(t, 24, p.IPHdrLen)
-	assert.False(t, p.FragAny)
-
-	// Plain IPv6 TCP: L4 at 40.
-	v6 := make([]byte, 60)
-	v6[0] = 0x60
-	v6[6] = iputil.IPProtocolTCP
-	require.NoError(t, newPacket(v6, true, p))
-	assert.Equal(t, 40, p.IPHdrLen)
-	assert.False(t, p.FragAny)
-
-	// IPv6 hop-by-hop then TCP: IPHdrLen lands past the extension header.
-	hbh := make([]byte, 60)
-	hbh[0] = 0x60
-	hbh[6] = 0 // hop-by-hop
-	hbh[40] = iputil.IPProtocolTCP
-	hbh[41] = 0 // HdrExtLen 0 -> 8-byte header
-	require.NoError(t, newPacket(hbh, true, p))
-	assert.Equal(t, 48, p.IPHdrLen)
-	assert.False(t, p.FragAny)
-
-	// IPv6 first fragment: terminal proto resolved, FragAny set, Fragment not.
-	f6 := make([]byte, 60)
-	f6[0] = 0x60
-	f6[6] = 44 // fragment extension header
-	f6[40] = iputil.IPProtocolUDP
-	require.NoError(t, newPacket(f6, true, p))
-	assert.True(t, p.FragAny)
-	assert.False(t, p.Fragment)
-	assert.Equal(t, uint8(iputil.IPProtocolUDP), p.Protocol)
-
-	// IPv6 non-first fragment: both set, walk stops at the fragment header.
-	f6n := make([]byte, 60)
-	f6n[0] = 0x60
-	f6n[6] = 44
-	f6n[40] = iputil.IPProtocolUDP
-	binary.BigEndian.PutUint16(f6n[42:44], 0x0008)
-	require.NoError(t, newPacket(f6n, true, p))
-	assert.True(t, p.Fragment)
-	assert.True(t, p.FragAny)
-}
@@ -1,187 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"math/rand"
-	"testing"
-)
-
-// The checksum-seeding helpers feed the virtio NEEDS_CSUM contract: the L4
-// checksum field is pre-loaded with the folded (not inverted) pseudo-header
-// sum, and the kernel later adds the L4 byte sum and inverts. A wrong seed
-// produces packets every receiver silently drops, with nothing failing on
-// our side — so these tests check the helpers against an independent
-// RFC 1071 reference built from explicit pseudo-header bytes, never against
-// the production checksum code.
-
-// refSum accumulates big-endian 16-bit words of b (odd tail zero-padded)
-// into a wide one's-complement accumulator.
-func refSum(b []byte) uint64 {
-	var s uint64
-	for i := 0; i+1 < len(b); i += 2 {
-		s += uint64(b[i])<<8 | uint64(b[i+1])
-	}
-	if len(b)%2 == 1 {
-		s += uint64(b[len(b)-1]) << 8
-	}
-	return s
-}
-
-// refFold folds a wide one's-complement accumulator to 16 bits.
-func refFold(s uint64) uint16 {
-	for s>>16 != 0 {
-		s = s&0xffff + s>>16
-	}
-	return uint16(s)
-}
-
-func TestFoldOnceNoInvertEdgeCases(t *testing.T) {
-	cases := []uint32{
-		0, 1, 0xffff,
-		0x10000,    // single carry
-		0x1fffe,    // 0xffff + 0xffff: carry produces another 0xffff
-		0xffff0000, // high half only
-		0xfffeffff, // fold yields 0x1fffd: needs a second fold
-		0xffffffff, // worst case
-		0x00010001, // simple two-word
-	}
-	for _, c := range cases {
-		want := refFold(uint64(c))
-		if got := foldOnceNoInvert(c); got != want {
-			t.Errorf("foldOnceNoInvert(%#x) = %#x, want %#x", c, got, want)
-		}
-		// Folding a folded value must be a no-op.
-		if got := foldOnceNoInvert(uint32(foldOnceNoInvert(c))); got != foldOnceNoInvert(c) {
-			t.Errorf("foldOnceNoInvert not idempotent at %#x", c)
-		}
-	}
-}
-
-func TestPseudoSumIPv4MatchesReference(t *testing.T) {
-	cases := []struct {
-		name     string
-		src, dst [4]byte
-		proto    byte
-		l4Len    int
-	}{
-		{"simple", [4]byte{10, 0, 0, 1}, [4]byte{10, 0, 0, 2}, 6, 20},
-		{"zero-len", [4]byte{192, 168, 1, 1}, [4]byte{192, 168, 1, 2}, 17, 0},
-		{"max-len", [4]byte{1, 2, 3, 4}, [4]byte{5, 6, 7, 8}, 6, 65535},
-		{"carry-heavy", [4]byte{255, 255, 255, 255}, [4]byte{255, 255, 255, 254}, 17, 65535},
-		{"broadcastish", [4]byte{255, 255, 255, 255}, [4]byte{255, 255, 255, 255}, 255, 65535},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			// RFC 793 pseudo-header: src(4) dst(4) zero(1) proto(1) len(2).
-			ph := make([]byte, 12)
-			copy(ph[0:4], c.src[:])
-			copy(ph[4:8], c.dst[:])
-			ph[9] = c.proto
-			binary.BigEndian.PutUint16(ph[10:12], uint16(c.l4Len))
-			want := refFold(refSum(ph))
-
-			got := foldOnceNoInvert(pseudoSumIPv4(c.src[:], c.dst[:], c.proto, c.l4Len))
-			if got != want {
-				t.Errorf("fold(pseudoSumIPv4) = %#x, want %#x", got, want)
-			}
-		})
-	}
-}
-
-func TestPseudoSumIPv6MatchesReference(t *testing.T) {
-	ones := func(b byte) (a [16]byte) {
-		for i := range a {
-			a[i] = b
-		}
-		return
-	}
-	cases := []struct {
-		name     string
-		src, dst [16]byte
-		proto    byte
-		l4Len    int
-	}{
-		{"simple", [16]byte{0xfe, 0x80, 15: 1}, [16]byte{0xfe, 0x80, 15: 2}, 6, 20},
-		{"zero-len", [16]byte{0x20, 0x01, 15: 9}, [16]byte{0x20, 0x01, 15: 8}, 17, 0},
-		{"max-u16-len", ones(0xff), ones(0xfe), 6, 65535},
-		{"len-past-u16", ones(0xff), ones(0xff), 17, 0x12345}, // exercises the 32-bit split
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			// RFC 8200 pseudo-header: src(16) dst(16) len(4) zero(3) next(1).
-			ph := make([]byte, 40)
-			copy(ph[0:16], c.src[:])
-			copy(ph[16:32], c.dst[:])
-			binary.BigEndian.PutUint32(ph[32:36], uint32(c.l4Len))
-			ph[39] = c.proto
-			want := refFold(refSum(ph))
-
-			got := foldOnceNoInvert(pseudoSumIPv6(c.src[:], c.dst[:], c.proto, c.l4Len))
-			if got != want {
-				t.Errorf("fold(pseudoSumIPv6) = %#x, want %#x", got, want)
-			}
-		})
-	}
-}
-
-func TestIPv4HdrChecksumMatchesReference(t *testing.T) {
-	rng := rand.New(rand.NewSource(0x1791))
-	for _, hdrLen := range []int{20, 24, 40, 60} {
-		for trial := 0; trial < 200; trial++ {
-			hdr := make([]byte, hdrLen)
-			rng.Read(hdr)
-			hdr[0] = 0x40 | byte(hdrLen/4)
-			hdr[10], hdr[11] = 0, 0 // checksum field zeroed, as the contract requires
-
-			want := ^refFold(refSum(hdr))
-			got := ipv4HdrChecksum(hdr)
-			if got != want {
-				t.Fatalf("ipv4HdrChecksum(len=%d trial=%d) = %#x, want %#x", hdrLen, trial, got, want)
-			}
-
-			// Receiver-side property: with the checksum stored, the full
-			// header must sum to all-ones.
-			binary.BigEndian.PutUint16(hdr[10:12], got)
-			if v := refFold(refSum(hdr)); v != 0xffff {
-				t.Fatalf("stored checksum does not validate: full-header fold = %#x", v)
-			}
-		}
-	}
-}
-
-// TestChecksumSeedReceiverAcceptance is the end-to-end property the helpers
-// exist for: seed the TCP checksum field with fold(pseudoSum), do what the
-// kernel's NEEDS_CSUM completion does (one's-complement sum over the L4
-// bytes including the seed, then invert, then store), and verify the result
-// the way a receiver does (pseudo-header + L4 must sum to all-ones).
-func TestChecksumSeedReceiverAcceptance(t *testing.T) {
-	rng := rand.New(rand.NewSource(0x1826))
-	for trial := 0; trial < 200; trial++ {
-		src := [4]byte{byte(rng.Intn(256)), byte(rng.Intn(256)), byte(rng.Intn(256)), byte(rng.Intn(256))}
-		dst := [4]byte{byte(rng.Intn(256)), byte(rng.Intn(256)), byte(rng.Intn(256)), byte(rng.Intn(256))}
-		payLen := rng.Intn(1500)
-		l4 := make([]byte, 20+payLen)
-		rng.Read(l4)
-
-		// Seed exactly as flushSlot does.
-		seed := foldOnceNoInvert(pseudoSumIPv4(src[:], dst[:], 6, len(l4)))
-		binary.BigEndian.PutUint16(l4[16:18], seed)
-
-		// Kernel NEEDS_CSUM completion: sum the L4 region (seed included,
-		// which is equivalent to summing with the field zeroed and folding
-		// the seed in), invert, store.
-		final := ^refFold(refSum(l4[:16]) + uint64(seed) + refSum(l4[18:]))
-		binary.BigEndian.PutUint16(l4[16:18], final)
-
-		// Receiver validation.
-		ph := make([]byte, 12)
-		copy(ph[0:4], src[:])
-		copy(ph[4:8], dst[:])
-		ph[9] = 6
-		binary.BigEndian.PutUint16(ph[10:12], uint16(len(l4)))
-		if v := refFold(refSum(ph) + refSum(l4)); v != 0xffff {
-			t.Fatalf("trial %d: receiver rejects packet: fold = %#x (seed=%#x final=%#x payLen=%d)",
-				trial, v, seed, final, payLen)
-		}
-	}
-}
@@ -1,169 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"encoding/binary"
-)
-
-// SortKey identifies a packet's position in its sender's transmission order.
-type SortKey struct {
-	// Epoch is a receiver-local ordinal for the tunnel (ConnectionState) that decrypted the packet:
-	// a re-handshake replaces the tunnel outright and the replacement's epoch is higher,
-	// so the old tunnel's packets sort first during the cutover overlap.
-	Epoch uint64
-	// Counter is the packet's AEAD message counter within that tunnel.
-	Counter uint64
-}
-
-// 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 UDP socket.
-const initialSlots = 64
-
-// parseIPAt validates the IP header for lane parsing. newPacket already resolved the L4 protocol
-// and offset for the firewall, so there is no proto sniff here; the caller's ipHdrLen is
-// cross-checked instead. A plain header (v4 IHL 20, v6 exactly 40) is the only coalesceable
-// shape. The v6 check is load-bearing: it rejects extension-header packets whose L4 is not at byte 40.
-//
-// The prologues fill fk's addresses and family in place (ports belong to the L4 parser; fk must
-// be zero on entry so the v4 path leaves src[4:]/dst[4:] clear for map equality) and return pkt
-// trimmed to the IP-declared length. The receiver-as-out-pointer shape is deliberate: these
-// functions are too big to inline, and returning structs by value put five 64-byte copies on the
-// per-packet path.
-func (fk *flowKey) parseIPAt(pkt []byte, ipHdrLen int) ([]byte, bool) {
-	if len(pkt) < 20 {
-		return nil, false
-	}
-	switch pkt[0] >> 4 {
-	case 4:
-		if ipHdrLen != 20 {
-			return nil, false
-		}
-		return fk.parseIPv4Prologue(pkt)
-	case 6:
-		if ipHdrLen != 40 || len(pkt) < 40 {
-			return nil, false
-		}
-		return fk.parseIPv6Prologue(pkt)
-	}
-	return nil, false
-}
-
-// parseIPv4Prologue is the shared IPv4 tail of the prologue entries; the caller has verified
-// len(pkt) >= 20 and the version.
-func (fk *flowKey) parseIPv4Prologue(pkt []byte) ([]byte, bool) {
-	ihl := int(pkt[0]&0x0f) * 4
-	if ihl != 20 {
-		return nil, false
-	}
-	// Reject any fragmentation (MF or nonzero offset). The dispatcher already gated FragAny; kept
-	// as defense in depth, since a fragment folded into a superpacket would corrupt reassembly.
-	if binary.BigEndian.Uint16(pkt[6:8])&0x3fff != 0 {
-		return nil, false
-	}
-	totalLen := int(binary.BigEndian.Uint16(pkt[2:4]))
-	if totalLen > len(pkt) || totalLen < ihl {
-		return nil, false
-	}
-	fk.isV6 = false
-	copy(fk.src[:4], pkt[12:16])
-	copy(fk.dst[:4], pkt[16:20])
-	return pkt[:totalLen], true
-}
-
-// parseIPv6Prologue is the shared IPv6 tail; the caller has verified len(pkt) >= 40, the version,
-// and that the L4 header sits at byte 40.
-func (fk *flowKey) parseIPv6Prologue(pkt []byte) ([]byte, bool) {
-	payloadLen := int(binary.BigEndian.Uint16(pkt[4:6]))
-	if 40+payloadLen > len(pkt) {
-		return nil, false
-	}
-	fk.isV6 = true
-	copy(fk.src[:], pkt[8:24])
-	copy(fk.dst[:], pkt[24:40])
-	return pkt[:40+payloadLen], 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 are masked out.
-// The full DSCP/ECN byte (IPv4 ToS / IPv6 traffic class) is compared, matching Linux kernel GRO:
-// segments with differing ECN codepoints must not coalesce,
-// otherwise ORing e.g. ECT(0) with ECT(1) would fabricate a false CE (congestion) mark or mark a Not-ECT flow as ECN-capable.
-//
-// 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: [0:4] = version/TC/flow label (TC[1:0] is ECN, so the full TC byte must match),
-		// [6:40] = next_hdr/hop + src + dst. Skip [4:6] payload_len.
-		return bytes.Equal(a[:4], b[:4]) && bytes.Equal(a[6:40], b[6:40])
-	}
-	// IPv4: [0:2] = version/IHL + DSCP|ECN (full ECN byte must match),
-	// [6:10] = flags/fragoff/TTL/proto, [12:20] = src+dst.
-	// Skip [2:4] total len, [4:6] id, [10:12] csum.
-	return bytes.Equal(a[:2], b[:2]) && bytes.Equal(a[6:10], b[6:10]) && bytes.Equal(a[12:20], b[12:20])
-}
-
-// ipv4FlagDF is the Don't Fragment bit in the IPv4 flags byte (header byte 6).
-const ipv4FlagDF = 0x40
-
-// ipv4CanCoalesceID reports whether an IPv4 packet whose header starts at
-// nextHdr may join a chain whose seed header is seedHdr as segment index seg
-// (the seed is segment 0). Kernel GSO re-stamps outgoing segment IDs as
-// seed_id+n, so coalescing is only transparent when that re-stamp is either
-// harmless (DF set: RFC 6864 atomic datagrams, the ID carries no meaning) or
-// reproduces the original IDs exactly (DF clear + IDs already sequential —
-// the same admission rule kernel GRO applies). Without this, a DF=0 sender
-// with non-sequential IDs (e.g. OpenBSD's randomized IDs) could have IDs
-// rewritten into ranges that collide across superpackets, corrupting
-// reassembly if the packets are fragmented after the TUN write.
-//
-// DF itself is guaranteed uniform across a chain by ipHeadersMatch (byte 6
-// is inside its compared range), so checking the seed's copy suffices.
-func ipv4CanCoalesceID(seedHdr, nextHdr []byte, seg int) bool {
-	if seedHdr[6]&ipv4FlagDF != 0 {
-		return true
-	}
-	expect := binary.BigEndian.Uint16(seedHdr[4:6]) + uint16(seg)
-	return binary.BigEndian.Uint16(nextHdr[4:6]) == expect
-}
-
-// Arena is an injectable byte-slab that hands out non-overlapping borrowed
-// slices via Reserve and releases them in bulk via Reset.
-type Arena struct {
-	buf []byte
-}
-
-// NewArena returns an Arena with a pre-allocated backing of the given capacity.
-func NewArena(capacity int) *Arena {
-	return &Arena{buf: make([]byte, 0, capacity)}
-}
-
-// Reserve hands out a non-overlapping sz-byte slice from the arena.
-// If the request doesn't fit the current backing, a fresh, larger backing is allocated.
-// Already-borrowed slices reference the old backing and remain valid until Reset.
-func (a *Arena) Reserve(sz int) []byte {
-	if len(a.buf)+sz > cap(a.buf) {
-		newCap := max(cap(a.buf)*2, sz)
-		a.buf = make([]byte, 0, newCap)
-	}
-	start := len(a.buf)
-	a.buf = a.buf[:start+sz]
-	return a.buf[start : start+sz : start+sz]
-}
-
-// Reset releases every slice handed out since the last Reset.
-// Callers must not use any previously-borrowed slice after this returns.
-// The underlying backing array is retained so subsequent Reserves don't re-allocate.
-func (a *Arena) Reset() {
-	a.buf = a.buf[:0]
-}
@@ -1,112 +0,0 @@
-package batch
-
-import (
-	"testing"
-
-	"github.com/slackhq/nebula/test"
-)
-
-// stagePackets builds the stagedPacket entries Commit would have produced, so dispatch benchmarks
-// bypass staging and the sort entirely.
-func stagePackets(pkts [][]byte) []stagedPacket {
-	staged := make([]stagedPacket, len(pkts))
-	for i, p := range pkts {
-		pp := testPP(p)
-		staged[i] = stagedPacket{
-			pkt:      p,
-			key:      SortKey{Epoch: 1, Counter: uint64(i + 1)},
-			proto:    pp.Protocol,
-			fragAny:  pp.FragAny,
-			ipHdrLen: uint16(pp.IPHdrLen),
-		}
-	}
-	return staged
-}
-
-func flushLanes(b *testing.B, m *MultiCoalescer) {
-	b.Helper()
-	if m.tcp != nil {
-		if err := m.tcp.Flush(); err != nil {
-			b.Fatal(err)
-		}
-	}
-	if m.udp != nil {
-		if err := m.udp.Flush(); err != nil {
-			b.Fatal(err)
-		}
-	}
-	if err := m.pt.Flush(); err != nil {
-		b.Fatal(err)
-	}
-}
-
-// runDispatchBench measures dispatch plus the per-batch lane flush: the post-sort half of the
-// batcher, which is where the production profile concentrates.
-func runDispatchBench(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, test.NewLogger())
-	staged := stagePackets(pkts)
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		if err := m.dispatch(staged[i%len(staged)]); err != nil {
-			b.Fatal(err)
-		}
-		if (i+1)%batchSize == 0 {
-			flushLanes(b, m)
-		}
-	}
-	b.StopTimer()
-	flushLanes(b, m)
-}
-
-// BenchmarkDispatchSingleFlow is the bulk steady state: every packet past the seed appends.
-func BenchmarkDispatchSingleFlow(b *testing.B) {
-	runDispatchBench(b, buildTCPv4BulkFlow(tcpCoalesceMaxSegs, 1200), tcpCoalesceMaxSegs)
-}
-
-// BenchmarkDispatchInterleaved16 stresses the openSlots map: 16 flows round-robined defeats the
-// lastSlot cache on every packet.
-func BenchmarkDispatchInterleaved16(b *testing.B) {
-	pkts := buildTCPv4Interleaved(16, tcpCoalesceMaxSegs, 1200)
-	runDispatchBench(b, pkts, len(pkts))
-}
-
-// BenchmarkDispatchAckHeavy alternates MSS data with pure ACKs on one flow — the RX shape of a
-// bidirectional transfer (the peer's data and its ACKs of our data share the tunnel direction).
-func BenchmarkDispatchAckHeavy(b *testing.B) {
-	pay := make([]byte, 1200)
-	var pkts [][]byte
-	seq := uint32(1000)
-	for range tcpCoalesceMaxSegs / 2 {
-		pkts = append(pkts, buildTCPv4(seq, tcpAck, pay))
-		seq += uint32(len(pay))
-		pkts = append(pkts, buildTCPv4(seq, tcpAck, nil))
-	}
-	runDispatchBench(b, pkts, len(pkts))
-}
-
-// BenchmarkDispatchUDPFlow is the QUIC-ish bulk UDP shape.
-func BenchmarkDispatchUDPFlow(b *testing.B) {
-	pay := make([]byte, 1200)
-	pkts := make([][]byte, udpCoalesceMaxSegs)
-	for i := range pkts {
-		pkts[i] = buildUDPv4(2000, 443, pay)
-	}
-	runDispatchBench(b, pkts, len(pkts))
-}
-
-// BenchmarkDispatchSeedHeavy sets PSH on every packet so each one seeds and immediately closes
-// its own slot — the small-write RPC shape, and the upper bound on what the seed path (including
-// the parsedTCP-to-slot field transfer) can cost.
-func BenchmarkDispatchSeedHeavy(b *testing.B) {
-	pay := make([]byte, 1200)
-	pkts := make([][]byte, tcpCoalesceMaxSegs)
-	seq := uint32(1000)
-	for i := range pkts {
-		pkts[i] = buildTCPv4(seq, tcpAckPsh, pay)
-		seq += uint32(len(pay))
-	}
-	runDispatchBench(b, pkts, len(pkts))
-}
@@ -1,76 +0,0 @@
-package batch
-
-//TODO refactor this away
-// This file holds the lanes' self-parsing Commit entries and the proto-checking parsers behind
-// them. Production traffic enters the lanes only through MultiCoalescer.dispatch and the At
-// parsers; these wrappers reproduce that path (including seal-all on unparseable shapes) on top
-// of a local parse, so tests and benches can drive one lane with nothing but a packet.
-
-// parseIPPrologue resolves the IP version, requires the L4 protocol to match wantProto (6 TCP,
-// 17 UDP), and defers to the shared per-version cores. Returns the trimmed packet and the L4
-// offset; fk must be zero on entry and is filled in place.
-func (fk *flowKey) parseIPPrologue(pkt []byte, wantProto byte) ([]byte, int, bool) {
-	if len(pkt) < 20 {
-		return nil, 0, false
-	}
-	switch pkt[0] >> 4 {
-	case 4:
-		if pkt[9] != wantProto {
-			return nil, 0, false
-		}
-		trimmed, ok := fk.parseIPv4Prologue(pkt)
-		return trimmed, 20, ok
-	case 6:
-		if len(pkt) < 40 {
-			return nil, 0, false
-		}
-		if pkt[6] != wantProto {
-			return nil, 0, false
-		}
-		trimmed, ok := fk.parseIPv6Prologue(pkt)
-		return trimmed, 40, ok
-	}
-	return nil, 0, false
-}
-
-// parseBase extracts the flow key and IP/TCP offsets for any TCP packet, admissible for
-// coalescing or not. Returns false for non-TCP or malformed input.
-func (p *parsedTCP) parseBase(pkt []byte) bool {
-	trimmed, ipHdrLen, ok := p.fk.parseIPPrologue(pkt, ipProtoTCP)
-	if !ok {
-		return false
-	}
-	return p.parseTail(trimmed, ipHdrLen)
-}
-
-// parseBase extracts the flow key and IP/UDP offsets for a UDP packet.
-func (p *parsedUDP) parseBase(pkt []byte) bool {
-	trimmed, ipHdrLen, ok := p.fk.parseIPPrologue(pkt, ipProtoUDP)
-	if !ok {
-		return false
-	}
-	return p.parseTail(trimmed, ipHdrLen)
-}
-
-// Commit borrows pkt. The caller must keep pkt valid until the next Flush.
-func (c *TCPCoalescer) Commit(pkt []byte) error {
-	var info parsedTCP
-	if !info.parseBase(pkt) {
-		// Unparseable: flow key unknown, seal everything so later data cannot emit ahead of it.
-		c.sealAllOpen()
-		c.addVerbatim(pkt)
-		return nil
-	}
-	return c.commitParsed(pkt, &info)
-}
-
-// Commit borrows pkt. The caller must keep pkt valid until the next Flush.
-func (c *UDPCoalescer) Commit(pkt []byte) error {
-	var info parsedUDP
-	if !info.parseBase(pkt) {
-		c.sealAllOpen()
-		c.addVerbatim(pkt)
-		return nil
-	}
-	return c.commitParsed(pkt, &info)
-}
@@ -1,133 +0,0 @@
-package batch
-
-import (
-	"cmp"
-	"errors"
-	"io"
-	"log/slog"
-	"slices"
-
-	"github.com/slackhq/nebula/firewall"
-)
-
-// MultiCoalescer stages plaintext packets with their (epoch, counter) sort keys and, at Flush,
-// replays them in sender-transmission order into lane-specific batchers selected by L4 protocol.
-//
-// Sorting before dispatch keeps the ordering story simple: each lane consumes packets in
-// transmission order, builds slots in that order, and emits them in creation order. Wire reorder
-// inside a flush batch is repaired here, before it can fragment a lane's coalesce chains, so the
-// lanes carry no reorder-repair machinery.
-//
-// The contract is per-tunnel transmission order within each lane, with two exceptions: a pure TCP
-// ACK may be overtaken by later same-flow data (it does not close the flow's open chain; a late
-// ACK is just a stale ACK), and an unparseable shape seals every open chain in its lane (its flow
-// is unknown) and rides the lane as an in-lane verbatim, still in transmission order. Routing
-// follows the flow: a flow's non-coalesceable shapes ride its protocol lane rather than falling
-// to the later-flushed pt lane.
-//
-// Cross-lane order (TCP vs UDP vs everything else) is not preserved.
-type MultiCoalescer struct {
-	tcp *TCPCoalescer
-	udp *UDPCoalescer
-	pt  *Passthrough
-
-	// staged holds this batch's packets and sort keys until Flush. Borrowed: the caller keeps
-	// each pkt alive until Flush returns.
-	staged []stagedPacket
-}
-
-// stagedPacket carries the scalars dispatch needs from the firewall's ParsedPacket, copied by
-// value: pp is reused by the caller per packet and must not be retained past Commit.
-type stagedPacket struct {
-	pkt      []byte
-	key      SortKey
-	proto    byte
-	fragAny  bool
-	ipHdrLen uint16
-}
-
-// NewMultiCoalescer builds a multi-lane batcher over w, based on available protocol support. The
-// staging sort applies even when no GSO lane is available: passthrough-only platforms still get
-// transmission-order repair.
-func NewMultiCoalescer(w io.Writer, l *slog.Logger) *MultiCoalescer {
-	m := &MultiCoalescer{
-		pt:     NewPassthrough(w),
-		staged: make([]stagedPacket, 0, initialSlots),
-	}
-	m.tcp = NewTCPCoalescer(w, l)
-	m.udp = NewUDPCoalescer(w)
-	return m
-}
-
-// Commit stages pkt for the next Flush; dispatch is deferred so it runs on packets already in
-// transmission order. key carries the packet's tunnel epoch and message counter. pkt is borrowed:
-// the caller must keep it valid until the next Flush and not re-use it, and Flush may patch a
-// coalesced packet's headers in place. pp is the firewall's parse of pkt and is borrowed only
-// for this call, so the fields dispatch needs are copied here.
-func (m *MultiCoalescer) Commit(pkt []byte, key SortKey, pp *firewall.ParsedPacket) error {
-	m.staged = append(m.staged, stagedPacket{
-		pkt:      pkt,
-		key:      key,
-		proto:    pp.Protocol,
-		fragAny:  pp.FragAny,
-		ipHdrLen: uint16(pp.IPHdrLen),
-	})
-	return nil
-}
-
-// compareStaged orders staged packets by (epoch, counter)
-func compareStaged(a, b stagedPacket) int {
-	if c := cmp.Compare(a.key.Epoch, b.key.Epoch); c != 0 {
-		return c
-	}
-	return cmp.Compare(a.key.Counter, b.key.Counter)
-}
-
-// dispatch routes one staged packet to its protocol lane (see commitStaged), or to the verbatim
-// passthrough when the lane has no GSO support.
-func (m *MultiCoalescer) dispatch(sp stagedPacket) error {
-	switch sp.proto {
-	case ipProtoTCP:
-		if m.tcp != nil {
-			return m.tcp.commitStaged(sp)
-		}
-	case ipProtoUDP:
-		if m.udp != nil {
-			return m.udp.commitStaged(sp)
-		}
-	}
-	return m.pt.enqueue(sp.pkt)
-}
-
-// Flush sorts the staged batch into transmission order, replays it into the lanes, then flushes each lane.
-// Drains everything and returns the joined errors; one bad packet does not hold up the rest.
-// After Flush returns, committed payload slices may be recycled.
-func (m *MultiCoalescer) Flush() error {
-	// Arrival order is already almost sorted (reorder is the exception), which pdqsort detects
-	// and handles in near-linear time.
-	slices.SortFunc(m.staged, compareStaged)
-
-	var errs []error
-	for _, sp := range m.staged {
-		if err := m.dispatch(sp); err != nil {
-			errs = append(errs, err)
-		}
-	}
-	clear(m.staged) // drop borrowed pkt refs
-	m.staged = m.staged[:0]
-
-	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)
-	}
-	return errors.Join(errs...)
-}
@@ -1,437 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"encoding/binary"
-	"io"
-	"testing"
-
-	"github.com/slackhq/nebula/firewall"
-	"github.com/slackhq/nebula/test"
-)
-
-// keySeq hands out SortKeys with ascending counters in a fixed epoch, for
-// tests where commit order IS transmission order.
-type keySeq struct {
-	epoch, counter uint64
-}
-
-func (k *keySeq) next() SortKey {
-	k.counter++
-	return SortKey{Epoch: k.epoch, Counter: k.counter}
-}
-
-// newTestMultiCoalescer builds a batcher over w.
-func newTestMultiCoalescer(tb testing.TB, w io.Writer) *MultiCoalescer {
-	tb.Helper()
-	return NewMultiCoalescer(w, test.NewLogger())
-}
-
-// 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 := newTestMultiCoalescer(t, w)
-	k := &keySeq{epoch: 1}
-
-	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), k.next(), testPP(buildTCPv4(1000, tcpAck, tcpPay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(2200, tcpAck, tcpPay), k.next(), testPP(buildTCPv4(2200, tcpAck, tcpPay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv4(2000, 53, udpPay), k.next(), testPP(buildUDPv4(2000, 53, udpPay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv4(2000, 53, udpPay), k.next(), testPP(buildUDPv4(2000, 53, udpPay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(icmp, k.next(), testPP(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))
-	}
-}
-
-// TestMultiCoalescerRestoresTransmissionOrder is the core staging-sort
-// property: packets committed out of counter order (wire reorder inside one
-// flush batch) are replayed into the lanes in transmission order, so the
-// reorder never fragments the coalesce chain — one superpacket, in seq
-// order, exactly as if the wire had never reordered. The retransmit shape
-// falls out of the same key: a retransmit carries a lower seq but a HIGHER
-// counter (it was encrypted later), so it emits after the data it trails.
-func TestMultiCoalescerRestoresTransmissionOrder(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := newTestMultiCoalescer(t, w)
-	pay := make([]byte, 1200)
-
-	// Transmission order: seq 1000 (c1), 2200 (c2), 3400 (c3).
-	// Arrival order: 3400, 1000, 2200.
-	if err := m.Commit(buildTCPv4(3400, tcpAck, pay), SortKey{Epoch: 1, Counter: 3}, testPP(buildTCPv4(3400, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(1000, tcpAck, pay), SortKey{Epoch: 1, Counter: 1}, testPP(buildTCPv4(1000, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(2200, tcpAck, pay), SortKey{Epoch: 1, Counter: 2}, testPP(buildTCPv4(2200, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 1 || len(w.writes) != 0 {
-		t.Fatalf("want 1 gso write (unfragmented chain), got gso=%d plain=%d", len(w.gsoWrites), len(w.writes))
-	}
-	g := w.gsoWrites[0]
-	if len(g.pays) != 3 {
-		t.Fatalf("segs=%d want 3", len(g.pays))
-	}
-	const ipHdrLen = 20
-	if seedSeq := binary.BigEndian.Uint32(g.hdr[ipHdrLen+4 : ipHdrLen+8]); seedSeq != 1000 {
-		t.Errorf("seed seq=%d want 1000", seedSeq)
-	}
-
-	// Retransmit: seq 1000 again but counter 4 — sorts after seq 4600 (c3).
-	w.writes, w.gsoWrites, w.order = nil, nil, nil
-	if err := m.Commit(buildTCPv4(1000, tcpAck, pay), SortKey{Epoch: 1, Counter: 4}, testPP(buildTCPv4(1000, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(4600, tcpAck, pay), SortKey{Epoch: 1, Counter: 3}, testPP(buildTCPv4(4600, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 2 {
-		t.Fatalf("want 2 plain writes, got %d (gso=%d)", len(w.writes), len(w.gsoWrites))
-	}
-	first := binary.BigEndian.Uint32(w.writes[0][24:28])
-	second := binary.BigEndian.Uint32(w.writes[1][24:28])
-	if first != 4600 || second != 1000 {
-		t.Fatalf("emission (%d, %d), want (4600, 1000): retransmit must not overtake in-flight data", first, second)
-	}
-}
-
-// TestMultiCoalescerRestoresOrderAcrossFlows scrambles two interleaved flows;
-// the staging sort must repair each flow into one superpacket without any
-// cross-flow contamination.
-func TestMultiCoalescerRestoresOrderAcrossFlows(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := newTestMultiCoalescer(t, w)
-	pay := make([]byte, 1200)
-
-	// Transmission: A.100 (c1), B.500 (c2), A.1300 (c3), B.1700 (c4).
-	// Arrival: A.1300, B.1700, A.100, B.500.
-	if err := m.Commit(buildTCPv4Ports(1000, 2000, 1300, tcpAck, pay), SortKey{Epoch: 1, Counter: 3}, testPP(buildTCPv4Ports(1000, 2000, 1300, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4Ports(3000, 2000, 1700, tcpAck, pay), SortKey{Epoch: 1, Counter: 4}, testPP(buildTCPv4Ports(3000, 2000, 1700, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4Ports(1000, 2000, 100, tcpAck, pay), SortKey{Epoch: 1, Counter: 1}, testPP(buildTCPv4Ports(1000, 2000, 100, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4Ports(3000, 2000, 500, tcpAck, pay), SortKey{Epoch: 1, Counter: 2}, testPP(buildTCPv4Ports(3000, 2000, 500, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 gso writes (one per flow), got %d (plain=%d)", len(w.gsoWrites), len(w.writes))
-	}
-	for i, g := range w.gsoWrites {
-		if len(g.pays) != 2 {
-			t.Errorf("gso[%d] segs=%d want 2", i, len(g.pays))
-		}
-		const ipHdrLen = 20
-		seedSeq := binary.BigEndian.Uint32(g.hdr[ipHdrLen+4 : ipHdrLen+8])
-		sport := binary.BigEndian.Uint16(g.hdr[ipHdrLen : ipHdrLen+2])
-		switch sport {
-		case 1000:
-			if seedSeq != 100 {
-				t.Errorf("flow A seed seq=%d want 100", seedSeq)
-			}
-		case 3000:
-			if seedSeq != 500 {
-				t.Errorf("flow B seed seq=%d want 500", seedSeq)
-			}
-		default:
-			t.Errorf("unexpected sport %d", sport)
-		}
-	}
-}
-
-// TestMultiCoalescerEpochOrdersAcrossRehandshake: a re-handshake replaces
-// the tunnel, and the replacement's counter space starts near zero — raw
-// counter order would emit the new tunnel's packets first while the old
-// tunnel's backlog is still arriving. The epoch key must dominate:
-// everything from the old tunnel emits before anything from the new one.
-func TestMultiCoalescerEpochOrdersAcrossRehandshake(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := newTestMultiCoalescer(t, w)
-	pay := make([]byte, 1200)
-
-	// New session's first data arrives before the old session's last data.
-	if err := m.Commit(buildTCPv4(2200, tcpAck, pay), SortKey{Epoch: 8, Counter: 1}, testPP(buildTCPv4(2200, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(1000, tcpAck, pay), SortKey{Epoch: 7, Counter: 9_000_000}, testPP(buildTCPv4(1000, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	// Same flow, contiguous seq, identical headers: after the epoch sort the
-	// two segments append into one superpacket seeded by the OLD session's
-	// packet.
-	if len(w.gsoWrites) != 1 {
-		t.Fatalf("want 1 gso write, got %d (plain=%d)", len(w.gsoWrites), len(w.writes))
-	}
-	const ipHdrLen = 20
-	if seedSeq := binary.BigEndian.Uint32(w.gsoWrites[0].hdr[ipHdrLen+4 : ipHdrLen+8]); seedSeq != 1000 {
-		t.Errorf("seed seq=%d want 1000 (old session first)", seedSeq)
-	}
-}
-
-// TestMultiCoalescerNoUSOFallsThrough verifies that on a queue without USO
-// (older kernel: TSO but no GSO_UDP_L4) the UDP lane never comes up and UDP
-// packets still reach the kernel via verbatim rather than being lost.
-func TestMultiCoalescerNoUSOFallsThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true, noUSO: true}
-	m := newTestMultiCoalescer(t, w)
-	k := &keySeq{epoch: 1}
-	if m.udp != nil {
-		t.Fatal("UDP lane must not come up without USO")
-	}
-
-	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv4(1000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800)), k.next(), testPP(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))
-	}
-}
-
-// TestMultiCoalescerNoOffloadsStillSorts covers a queue that can't offload
-// anything. Both lane constructors refuse, so every packet rides the
-// verbatim lane — but the staging sort still applies, so emission follows
-// transmission order even without GSO.
-func TestMultiCoalescerNoOffloadsStillSorts(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: false}
-	m := newTestMultiCoalescer(t, w)
-	if m.tcp != nil || m.udp != nil {
-		t.Fatal("no lane may come up without offloads")
-	}
-	pkts := [][]byte{
-		buildTCPv4(1000, tcpAck, make([]byte, 1200)),
-		buildUDPv4(1000, 53, make([]byte, 800)),
-		buildTCPv4(2200, tcpAck, make([]byte, 1200)),
-	}
-	// Committed in reverse transmission order; keys carry the truth.
-	for i := len(pkts) - 1; i >= 0; i-- {
-		if err := m.Commit(pkts[i], SortKey{Epoch: 1, Counter: uint64(i + 1)}, testPP(pkts[i])); err != nil {
-			t.Fatal(err)
-		}
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 0 {
-		t.Errorf("no GSO writes possible, got %d", len(w.gsoWrites))
-	}
-	if len(w.writes) != len(pkts) {
-		t.Fatalf("want %d plain writes, got %d", len(pkts), len(w.writes))
-	}
-	// One lane for everything means the sorted order survives end to end.
-	for i, want := range pkts {
-		if !bytes.Equal(w.writes[i], want) {
-			t.Errorf("write %d out of order or corrupt", i)
-		}
-	}
-}
-
-// buildUDPv6Fragment builds an IPv6 packet whose extension chain is a
-// single fragment header (NH=44) naming UDP as the terminal protocol —
-// a first fragment (offset 0, MF set) carrying the UDP header and a
-// partial payload.
-func buildUDPv6Fragment(sport, dport uint16, payload []byte) []byte {
-	const ipHdrLen = 40
-	const fragHdrLen = 8
-	const udpHdrLen = 8
-	total := ipHdrLen + fragHdrLen + udpHdrLen + len(payload)
-	pkt := make([]byte, total)
-
-	pkt[0] = 0x60
-	binary.BigEndian.PutUint16(pkt[4:6], uint16(total-ipHdrLen))
-	pkt[6] = 44 // fragment extension header
-	pkt[7] = 64
-	pkt[8] = 0xfe
-	pkt[9] = 0x80
-	pkt[23] = 1
-	pkt[24] = 0xfe
-	pkt[25] = 0x80
-	pkt[39] = 2
-
-	pkt[40] = ipProtoUDP                              // fragment's next header
-	binary.BigEndian.PutUint16(pkt[42:44], 0x0001)    // offset 0, MF set
-	binary.BigEndian.PutUint32(pkt[44:48], 0x1badf00) // identification
-
-	binary.BigEndian.PutUint16(pkt[48:50], sport)
-	binary.BigEndian.PutUint16(pkt[50:52], dport)
-	binary.BigEndian.PutUint16(pkt[52:54], uint16(udpHdrLen+len(payload)))
-	copy(pkt[56:], payload)
-	return pkt
-}
-
-// TestMultiCoalescerIPv6FragmentStaysInLane locks in extension-header
-// routing: a fragment whose chain terminates in UDP must ride the UDP lane
-// as an in-lane verbatim — emitted ahead of later same-flow datagrams —
-// not the verbatim lane, which flushes after every coalescer lane and
-// would reorder it behind data that arrived after it.
-func TestMultiCoalescerIPv6FragmentStaysInLane(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := newTestMultiCoalescer(t, w)
-	k := &keySeq{epoch: 1}
-
-	if err := m.Commit(buildUDPv6Fragment(2000, 53, make([]byte, 512)), k.next(), testPP(buildUDPv6Fragment(2000, 53, make([]byte, 512)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv6(2000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv6(2000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv6(2000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv6(2000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 1 {
-		t.Fatalf("want the fragment as 1 plain write, got %d", len(w.writes))
-	}
-	if len(w.gsoWrites) != 1 {
-		t.Fatalf("want the two whole datagrams coalesced into 1 gso write, got %d", len(w.gsoWrites))
-	}
-	// Transmission order was fragment-then-data; same-lane routing must keep it.
-	if w.order[0] != "write" {
-		t.Fatalf("fragment must be emitted before later data (in-lane verbatim), order=%v", w.order)
-	}
-}
-
-// TestMultiCoalescerFragmentSealsUDPChains: an unparseable datagram
-// (fragment) seals every open UDP chain, so datagrams from before and after
-// it land in separate superpackets and the fragment holds its transmission-
-// order position between them.
-func TestMultiCoalescerFragmentSealsUDPChains(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	m := newTestMultiCoalescer(t, w)
-	k := &keySeq{epoch: 1}
-
-	if err := m.Commit(buildUDPv6(2000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv6(2000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv6(2000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv6(2000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv6Fragment(2000, 53, make([]byte, 512)), k.next(), testPP(buildUDPv6Fragment(2000, 53, make([]byte, 512)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv6(2000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv6(2000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildUDPv6(2000, 53, make([]byte, 800)), k.next(), testPP(buildUDPv6(2000, 53, make([]byte, 800)))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 2 {
-		t.Fatalf("want 2 gso writes (chains sealed around the fragment), got %d", len(w.gsoWrites))
-	}
-	if len(w.writes) != 1 {
-		t.Fatalf("want the fragment as 1 plain write, got %d", len(w.writes))
-	}
-	want := []string{"gso", "write", "gso"}
-	if len(w.order) != 3 || w.order[0] != want[0] || w.order[1] != want[1] || w.order[2] != want[2] {
-		t.Fatalf("emission order = %v, want %v", w.order, want)
-	}
-}
-
-// TestMultiCoalescerNoTSOFallsThrough mirrors the no-TSO case.
-func TestMultiCoalescerNoTSOFallsThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true, noTSO: true}
-	m := newTestMultiCoalescer(t, w)
-	k := &keySeq{epoch: 1}
-	if m.tcp != nil {
-		t.Fatal("TCP lane must not come up without TSO")
-	}
-
-	pay := make([]byte, 1200)
-	if err := m.Commit(buildTCPv4(1000, tcpAck, pay), k.next(), testPP(buildTCPv4(1000, tcpAck, pay))); err != nil {
-		t.Fatal(err)
-	}
-	if err := m.Commit(buildTCPv4(2200, tcpAck, pay), k.next(), testPP(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))
-	}
-}
-
-// testPP derives the ParsedPacket newPacket would produce for the packet
-// shapes the tests build: plain v4/v6, v4 with options or fragment bits set,
-// and the single-fragment-header v6 shape from buildUDPv6Fragment. Anything
-// unrecognizable stays zero (proto 0 routes to the passthrough lane).
-func testPP(pkt []byte) *firewall.ParsedPacket {
-	pp := &firewall.ParsedPacket{}
-	if len(pkt) < 20 {
-		return pp
-	}
-	switch pkt[0] >> 4 {
-	case 4:
-		pp.Protocol = pkt[9]
-		pp.IPHdrLen = int(pkt[0]&0x0f) * 4
-		pp.FragAny = binary.BigEndian.Uint16(pkt[6:8])&0x3fff != 0
-	case 6:
-		pp.Protocol = pkt[6]
-		pp.IPHdrLen = 40
-		if pp.Protocol == 44 { // fragment extension header
-			pp.Protocol = pkt[40]
-			pp.IPHdrLen = 48
-			pp.FragAny = true
-		}
-	}
-	return pp
-}
@@ -1,38 +0,0 @@
-package batch
-
-import (
-	"io"
-)
-
-// Passthrough is MultiCoalescer's verbatim lane: no batching, packets are written at Flush in the
-// order enqueued.
-type Passthrough struct {
-	out   io.Writer
-	slots [][]byte
-}
-
-func NewPassthrough(w io.Writer) *Passthrough {
-	return &Passthrough{
-		out:   w,
-		slots: make([][]byte, 0, 128),
-	}
-}
-
-// enqueue accepts one packet, already sorted into transmission order by dispatch.
-func (p *Passthrough) enqueue(pkt []byte) error {
-	p.slots = append(p.slots, pkt)
-	return nil
-}
-
-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]
-	return firstErr
-}
@@ -1,472 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"encoding/binary"
-	"io"
-	"log/slog"
-
-	"github.com/slackhq/nebula/overlay/tio"
-)
-
-// ipProtoTCP is the IANA protocol number for TCP. Defined here to help Windows out.
-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
-
-// coalesceSlot is one entry in the coalescer's ordered event queue. A verbatim slot holds a single
-// borrowed packet emitted as-is (pure ACK, non-admissible TCP, unparseable, or oversize seed); a
-// non-verbatim slot is an in-progress coalesced superpacket. payIovs are borrowed slices of the
-// caller's plaintext buffers; the caller must keep them alive until Flush.
-type coalesceSlot struct {
-	verbatim bool
-	// rawPkt is borrowed: the whole packet for verbatim slots, the seed packet for coalesce
-	// slots. A slot that never grows past one segment is emitted from rawPkt so its original
-	// (already valid) L4 checksum ships DATA_VALID instead of making the kernel recompute it.
-	// A multi-segment slot's superpacket header is rawPkt's, patched in place at flush.
-	rawPkt []byte
-
-	fk       flowKey
-	hdrLen   int
-	ipHdrLen int
-	isV6     bool
-	gsoSize  int
-	numSeg   int
-	totalPay int
-	nextSeq  uint32
-	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. Input must be in sender
-// transmission order (MultiCoalescer sorts by (epoch, counter) before dispatch); slots are emitted
-// in creation order, so emission reproduces transmission order except for the pure-ACK case in
-// commitParsed. Owns no locks; one coalescer per TUN write queue.
-type TCPCoalescer struct {
-	w tio.GSOWriter
-
-	// slots is the ordered event queue. Flush walks it once and emits each
-	// entry as either a WriteGSO (coalesced) or a w.Write (verbatim).
-	slots []*coalesceSlot
-	// openSlots maps a flow key to its open slot so new segments can extend an in-progress
-	// superpacket in O(1). Removal is what closes a chain: on PSH or a short last segment, on a
-	// non-admissible packet for the flow, or in Flush.
-	openSlots map[flowKey]*coalesceSlot
-	// lastSlot caches the most recently touched open slot. Bulk traffic
-	// arrives in same-flow runs (single-flow steady state, or GRO bursts
-	// under multi-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) for the length of each run.
-	// Kept in lockstep with openSlots: nil whenever the slot it pointed
-	// at is removed.
-	lastSlot *coalesceSlot
-	pool     []*coalesceSlot // free list for reuse
-	l        *slog.Logger
-}
-
-// NewTCPCoalescer wraps w, returning nil if w can't accept GSO_TCP writes.
-func NewTCPCoalescer(w io.Writer, l *slog.Logger) *TCPCoalescer {
-	gw, ok := tio.SupportsGSO(w, tio.GSOProtoTCP)
-	if !ok {
-		return nil
-	}
-	return &TCPCoalescer{
-		w:         gw,
-		slots:     make([]*coalesceSlot, 0, initialSlots),
-		openSlots: make(map[flowKey]*coalesceSlot, initialSlots),
-		pool:      make([]*coalesceSlot, 0, initialSlots),
-		l:         l,
-	}
-}
-
-// 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
-	hdrLen   int
-	payLen   int
-	seq      uint32
-	flags    byte
-}
-
-// parseAt extracts the flow key and IP/TCP offsets for a packet the dispatcher already knows is
-// TCP; ipHdrLen is the upstream-resolved L4 offset (see flowKey.parseIPAt). p must be zero on
-// entry and is filled in place; see flowKey.parseIPAt for why. Returns false for malformed input
-// or any shape that must not coalesce (IPv4 options/fragmentation, IPv6 extension headers).
-func (p *parsedTCP) parseAt(pkt []byte, ipHdrLen int) bool {
-	trimmed, ok := p.fk.parseIPAt(pkt, ipHdrLen)
-	if !ok {
-		return false
-	}
-	return p.parseTail(trimmed, ipHdrLen)
-}
-
-// parseTail layers the TCP-header parse on a validated IP prologue. pkt is the trimmed packet;
-// fk's addresses are already filled.
-func (p *parsedTCP) parseTail(pkt []byte, ipHdrLen int) bool {
-	if len(pkt) < ipHdrLen+20 {
-		return false
-	}
-	tcpOff := int(pkt[ipHdrLen+12]>>4) * 4
-	if tcpOff < 20 || tcpOff > 60 {
-		return false
-	}
-	if len(pkt) < ipHdrLen+tcpOff {
-		return false
-	}
-	p.ipHdrLen = ipHdrLen
-	p.hdrLen = ipHdrLen + tcpOff
-	p.payLen = len(pkt) - p.hdrLen
-	p.fk.sport = binary.BigEndian.Uint16(pkt[ipHdrLen : ipHdrLen+2])
-	p.fk.dport = binary.BigEndian.Uint16(pkt[ipHdrLen+2 : ipHdrLen+4])
-	p.seq = binary.BigEndian.Uint32(pkt[ipHdrLen+4 : ipHdrLen+8])
-	p.flags = pkt[ipHdrLen+13]
-	return true
-}
-
-// TCP flag bits (byte 13 of the TCP header). Only the bits the coalescer consults are named;
-// FIN/SYN/RST/URG/CWR are rejected by the negative mask in commitParsed.
-const (
-	tcpFlagPsh = 0x08
-	tcpFlagAck = 0x10
-	tcpFlagEce = 0x40
-)
-
-// sealAllOpen closes every open coalesce chain. Called for unparseable packets: the flow key is
-// unknown, so any open chain could otherwise absorb later data and emit it ahead of this packet.
-func (c *TCPCoalescer) sealAllOpen() {
-	clear(c.openSlots)
-	c.lastSlot = nil
-}
-
-// sealFlow closes fk's open chain, if any, keeping lastSlot in lockstep. The len guard skips
-// hashing the 38-byte key when no chains are open (e.g. ack-dominant queues).
-func (c *TCPCoalescer) sealFlow(fk flowKey) {
-	if len(c.openSlots) == 0 {
-		return
-	}
-	if last := c.lastSlot; last != nil && last.fk == fk {
-		c.lastSlot = nil
-	}
-	delete(c.openSlots, fk)
-}
-
-// commitStaged commits one staged packet dispatch routed to this lane. A shape the lane cannot
-// coalesce (any fragmentation, unparseable header) seals every open chain
-// and rides the lane as an in-lane verbatim, still in transmission order.
-func (c *TCPCoalescer) commitStaged(sp stagedPacket) error {
-	if sp.fragAny {
-		c.sealAllOpen()
-		c.addVerbatim(sp.pkt)
-		return nil
-	}
-	var info parsedTCP
-	if !info.parseAt(sp.pkt, int(sp.ipHdrLen)) {
-		c.sealAllOpen()
-		c.addVerbatim(sp.pkt)
-		return nil
-	}
-	return c.commitParsed(sp.pkt, &info)
-}
-
-// commitParsed commits one parsed TCP packet. The caller (dispatch, via parseAt) supplies a
-// valid parse so the header is not re-walked here.
-func (c *TCPCoalescer) commitParsed(pkt []byte, info *parsedTCP) error {
-	// Admission: only ACK, ACK|PSH, ACK|ECE, ACK|PSH|ECE may ride a coalesce chain. CWR marks a
-	// one-shot congestion transition the receiver must observe at a segment boundary. NB: AccECN
-	// reuses CWR as ACE counter bits; revisit this check if inner hosts adopt AccECN.
-	if info.flags&tcpFlagAck == 0 || info.flags&^(tcpFlagAck|tcpFlagPsh|tcpFlagEce) != 0 {
-		// SYN/FIN/RST/URG/CWR must be observed in sequence. Seal the flow's open slot so later
-		// in-flow packets cannot extend it and emit ahead of this verbatim.
-		c.sealFlow(info.fk)
-		c.addVerbatim(pkt)
-		return nil
-	}
-	if info.payLen == 0 {
-		// Pure ACK: no ordering obligation toward the flow's data. Delivering it after
-		// later-transmitted data only makes it a stale ACK, which receivers ignore. Not sealing
-		// keeps a bidirectional flow's data run coalescing across interleaved peer ACKs, matching
-		// kernel GRO. This is the only place emission deviates from transmission order.
-		c.addVerbatim(pkt)
-		return nil
-	}
-
-	// Cached-slot fast path. Arrival isn't per-packet interleaved even with
-	// many flows: wire-side GRO delivers runs of same-flow packets
-	// (deliverSegments splits a superdatagram into up to 64), so the cache
-	// hits for the length of each run and a miss costs one fk compare
-	// before the map lookup carries the weight.
-	var open *coalesceSlot
-	if last := c.lastSlot; last != nil && last.fk == info.fk {
-		open = last
-	} else {
-		open = c.openSlots[info.fk]
-	}
-	if open != nil {
-		if c.canAppend(open, pkt, info) {
-			if c.appendPayload(open, pkt, info) {
-				// Chain closed (PSH or short segment): stop extending it.
-				c.sealFlow(info.fk)
-			} else {
-				c.lastSlot = open
-			}
-			return nil
-		}
-		// Can't extend (seq gap from upstream loss, header change, or a full
-		// chain): evict it from openSlots and fall through to seed a fresh slot.
-		c.sealFlow(info.fk)
-	}
-	c.seed(pkt, info)
-	return nil
-}
-
-func (c *TCPCoalescer) Flush() error {
-	var first error
-	for _, s := range c.slots {
-		var err error
-		if s.verbatim || s.numSeg == 1 {
-			// A slot that never grew is byte-identical to its seed packet; ship the original so
-			// its valid checksum rides the DATA_VALID path instead of a kernel software csum.
-			// rawPkt is only mutated once numSeg >= 2 (PSH propagate, flush patches), so it is
-			// pristine here.
-			_, err = c.w.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
-
-	return first
-}
-
-func (c *TCPCoalescer) addVerbatim(pkt []byte) {
-	s := c.take()
-	s.verbatim = true
-	s.rawPkt = pkt
-	c.slots = append(c.slots, s)
-}
-
-func (c *TCPCoalescer) seed(pkt []byte, info *parsedTCP) {
-	if info.hdrLen+info.payLen > tcpCoalesceBufSize {
-		// Pathological shape that can't ride a superpacket; emit as-is. No chain for this flow can
-		// be open here (commitParsed evicts before seeding), so sealFlow is defense in depth
-		// against a stale cache entry absorbing later data.
-		c.sealFlow(info.fk)
-		c.addVerbatim(pkt)
-		return
-	}
-	s := c.take()
-	s.verbatim = false
-	// rawPkt serves the numSeg==1 fast path in Flush, is the header source for canAppend, and is
-	// the superpacket header flushSlot patches in place.
-	s.rawPkt = pkt
-	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.payIovs = append(s.payIovs[:0], pkt[info.hdrLen:info.hdrLen+info.payLen])
-	c.slots = append(c.slots, s)
-	if info.flags&tcpFlagPsh == 0 {
-		c.openSlots[info.fk] = s
-		c.lastSlot = s
-	} else {
-		// PSH on the seed closes the chain immediately; it is never registered as open.
-		// Drop any stale entry for this flow too (defense in depth, unreachable if lastSlot's lockstep invariant holds).
-		c.sealFlow(info.fk)
-	}
-}
-
-// canAppend reports whether info's packet extends the slot's seed: same header shape and stable
-// contents, adjacent seq, not oversized. A closed chain never reaches here; closing removes the
-// slot from openSlots, the only path in. The header fields read from rawPkt are always pristine:
-// the only pre-flush mutation is the PSH propagate, which also closes the chain.
-func (c *TCPCoalescer) canAppend(s *coalesceSlot, pkt []byte, info *parsedTCP) bool {
-	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.rawPkt[s.ipHdrLen+13]
-	if (seedFlags^info.flags)&tcpFlagEce != 0 {
-		return false
-	}
-	if !s.isV6 && !ipv4CanCoalesceID(s.rawPkt, pkt, s.numSeg) {
-		return false
-	}
-	if !headersMatch(s.rawPkt[:s.hdrLen], pkt[:info.hdrLen], s.isV6, s.ipHdrLen) {
-		return false
-	}
-	return true
-}
-
-// appendPayload folds info's packet into s and reports whether the chain is now closed: the
-// segment was sub-gsoSize (kernel TSO allows only the final segment to be short) or carried PSH.
-// The caller must deregister a closed slot from openSlots.
-func (c *TCPCoalescer) appendPayload(s *coalesceSlot, pkt []byte, info *parsedTCP) bool {
-	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. Mutating
-		// rawPkt is safe: PSH also closes the chain, so no admission check re-reads this header.
-		s.rawPkt[s.ipHdrLen+13] |= tcpFlagPsh
-	}
-	return info.payLen < s.gsoSize || info.flags&tcpFlagPsh != 0
-}
-
-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) {
-	clear(s.payIovs)
-	*s = coalesceSlot{payIovs: s.payIovs[:0]}
-	c.pool = append(c.pool, s)
-}
-
-// flushSlot patches the superpacket header in place in rawPkt (total length, IPv4 header
-// checksum, pseudo-header checksum seed) and calls WriteGSO. The slot is released right after,
-// so nothing re-reads the patched header. 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.rawPkt[: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.w.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.
-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
-}
-
-// 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
-func foldOnceNoInvert(sum uint32) uint16 {
-	for sum>>16 != 0 {
-		sum = (sum & 0xffff) + (sum >> 16)
-	}
-	return uint16(sum)
-}
@@ -1,214 +0,0 @@
-package batch
-
-import (
-	"encoding/binary"
-	"testing"
-
-	"github.com/slackhq/nebula/firewall"
-	"github.com/slackhq/nebula/overlay/tio"
-	"github.com/slackhq/nebula/test"
-)
-
-// 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
-}
-
-// buildTCPv4RunInterleaved returns nFlows*perFlow packets delivered in
-// runs of runLen per flow — the arrival pattern wire-side GRO actually
-// produces (deliverSegments splits each superdatagram into up to 64
-// same-flow packets back to back). Contrast with buildTCPv4Interleaved's
-// per-packet round-robin, the adversarial worst case for a last-slot cache.
-func buildTCPv4RunInterleaved(nFlows, perFlow, runLen, 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 done := 0; done < perFlow; done += runLen {
-		for f := range nFlows {
-			sport := uint16(10000 + f)
-			for range runLen {
-				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 verbatim
-// 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 := newTestTCPCoalescer(b, 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))
-}
-
-// BenchmarkCommitRunInterleaved4 is 4 concurrent flows arriving in
-// GRO-burst runs of 16 — the realistic multi-flow pattern. A last-slot
-// cache hits for the length of each run; the per-packet round-robin
-// benches above are its worst case.
-func BenchmarkCommitRunInterleaved4(b *testing.B) {
-	pkts := buildTCPv4RunInterleaved(4, tcpCoalesceMaxSegs, 16, 1200)
-	runCommitBench(b, pkts, len(pkts))
-}
-
-// BenchmarkCommitPassthrough exercises the non-TCP branch: parseBase
-// bails early and addVerbatim 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 + verbatim. 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 with in-order keys, so
-// it includes the staging sort's already-sorted fast path plus the
-// dispatch-time parse — the full steady-state cost of the batcher. The
-// ParsedPackets are precomputed: in production they fall out of the
-// firewall's newPacket, which this bench does not model.
-func runMultiCommitBench(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, test.NewLogger())
-	pps := make([]*firewall.ParsedPacket, len(pkts))
-	for i, p := range pkts {
-		pps[i] = testPP(p)
-	}
-	b.ReportAllocs()
-	b.SetBytes(int64(len(pkts[0])))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		j := i % len(pkts)
-		if err := m.Commit(pkts[j], SortKey{Epoch: 1, Counter: uint64(i + 1)}, pps[j]); 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))
-}
@@ -1,59 +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) (int, error)
-}
-
-// SendBatch accumulates encrypted UDP packets and flushes them via WriteBatch.
-// One SendBatch is owned by each listenIn goroutine; no locking is needed.
-// Slots are backed by an Arena (see its docs)
-type SendBatch struct {
-	out   batchWriter
-	bufs  [][]byte
-	dsts  []netip.AddrPort
-	arena *Arena
-}
-
-// NewSendBatch makes a SendBatch with batchCap slots and an arenaSize byte buffer for slices to back those slots
-func NewSendBatch(out batchWriter, batchCap, arenaSize int) *SendBatch {
-	return &SendBatch{
-		out:   out,
-		bufs:  make([][]byte, 0, batchCap),
-		dsts:  make([]netip.AddrPort, 0, batchCap),
-		arena: NewArena(arenaSize),
-	}
-}
-
-func (b *SendBatch) Reserve(sz int) []byte {
-	return b.arena.Reserve(sz)
-}
-
-// Len reports how many packets are queued for the next Flush. Callers use
-// it to flush incrementally once a full sendmmsg batch has accumulated,
-// bounding how long the first packet of a large read batch waits.
-func (b *SendBatch) Len() int { return len(b.bufs) }
-
-func (b *SendBatch) Commit(pkt []byte, dst netip.AddrPort) {
-	b.bufs = append(b.bufs, pkt)
-	b.dsts = append(b.dsts, dst)
-}
-
-// Flush writes every queued packet and reports how many actually went out. A short count means some destinations
-// were undeliverable; the batch is drained either way.
-func (b *SendBatch) Flush() (int, error) {
-	var err error
-	written := 0
-	if len(b.bufs) > 0 {
-		written, err = b.out.WriteBatch(b.bufs, b.dsts)
-	}
-	clear(b.bufs)
-	b.bufs = b.bufs[:0]
-	b.dsts = b.dsts[:0]
-	b.arena.Reset()
-	return written, err
-}
@@ -1,122 +0,0 @@
-package batch
-
-import (
-	"net/netip"
-	"testing"
-)
-
-type fakeBatchWriter struct {
-	bufs  [][]byte
-	addrs []netip.AddrPort
-}
-
-func (w *fakeBatchWriter) WriteBatch(bufs [][]byte, addrs []netip.AddrPort) (int, 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...)
-	return len(bufs), 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)
-	}
-	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)
-	}
-	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)
-
-	s2 := b.Reserve(8) // exceeds remaining cap, triggers grow
-	pkt2 := append(s2[:0], 0xA, 0xB, 0xC, 0xD, 0xE)
-	b.Commit(pkt2, ap)
-
-	// 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])
-	}
-}
@@ -1,345 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"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
-
-// udpSlot is one entry in the UDPCoalescer's ordered event queue.
-type udpSlot struct {
-	verbatim bool
-	// rawPkt is borrowed: the whole packet for verbatim slots, the seed
-	// packet for coalesce slots. A coalesce slot that never grows past one
-	// segment is emitted from rawPkt so its original (already valid) L4
-	// checksum ships DATA_VALID instead of making the kernel recompute it.
-	// A multi-segment slot's superpacket header is rawPkt's, patched in place at flush.
-	rawPkt []byte
-
-	fk       flowKey
-	hdrLen   int
-	ipHdrLen int
-	isV6     bool
-	gsoSize  int // per-segment UDP payload length
-	numSeg   int
-	totalPay int
-	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.
-// Preserves the in-flow order of packets as they are Commit-ed
-//
-// Owns no locks; one coalescer per TUN write queue.
-type UDPCoalescer struct {
-	w         tio.GSOWriter
-	slots     []*udpSlot
-	openSlots map[flowKey]*udpSlot
-	// lastSlot caches the most recently touched open slot; see the
-	// TCPCoalescer field of the same name. Single-flow QUIC bulk is the
-	// dominant USO workload, and multi-flow arrival comes in GRO runs, so
-	// the fk compare beats the map's 38-byte key hash on most packets.
-	// Kept in lockstep with openSlots: nil whenever the slot it pointed at
-	// is removed.
-	lastSlot *udpSlot
-	pool     []*udpSlot
-}
-
-func NewUDPCoalescer(w io.Writer) *UDPCoalescer {
-	gw, ok := tio.SupportsGSO(w, tio.GSOProtoUDP)
-	if !ok {
-		return nil
-	}
-	return &UDPCoalescer{
-		w:         gw,
-		slots:     make([]*udpSlot, 0, initialSlots),
-		openSlots: make(map[flowKey]*udpSlot, initialSlots),
-		pool:      make([]*udpSlot, 0, initialSlots),
-	}
-}
-
-// 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
-}
-
-// parseAt extracts the flow key and IP/UDP offsets for a packet the dispatcher already knows is
-// UDP; ipHdrLen is the upstream-resolved L4 offset (see flowKey.parseIPAt). p must be zero on
-// entry and is filled in place. Returns false for malformed input or any shape that must not
-// coalesce (IPv4 options/fragmentation, IPv6 extension headers).
-func (p *parsedUDP) parseAt(pkt []byte, ipHdrLen int) bool {
-	trimmed, ok := p.fk.parseIPAt(pkt, ipHdrLen)
-	if !ok {
-		return false
-	}
-	return p.parseTail(trimmed, ipHdrLen)
-}
-
-// parseTail layers the UDP-header parse on a validated IP prologue. pkt is the trimmed packet;
-// fk's addresses are already filled.
-func (p *parsedUDP) parseTail(pkt []byte, ipHdrLen int) bool {
-	if len(pkt) < ipHdrLen+8 {
-		return false
-	}
-	// UDP `length` field: must equal IP-derived length-of-UDP-header-plus-payload.
-	udpLen := int(binary.BigEndian.Uint16(pkt[ipHdrLen+4 : ipHdrLen+6]))
-	if udpLen < 8 || udpLen > len(pkt)-ipHdrLen {
-		return false
-	}
-	p.ipHdrLen = ipHdrLen
-	p.hdrLen = ipHdrLen + 8
-	p.payLen = udpLen - 8
-	p.fk.sport = binary.BigEndian.Uint16(pkt[ipHdrLen : ipHdrLen+2])
-	p.fk.dport = binary.BigEndian.Uint16(pkt[ipHdrLen+2 : ipHdrLen+4])
-	return true
-}
-
-// sealFlow closes fk's open chain, if any, keeping lastSlot in lockstep. The len guard skips
-// hashing the 38-byte key when no chains are open.
-func (c *UDPCoalescer) sealFlow(fk flowKey) {
-	if len(c.openSlots) == 0 {
-		return
-	}
-	if last := c.lastSlot; last != nil && last.fk == fk {
-		c.lastSlot = nil
-	}
-	delete(c.openSlots, fk)
-}
-
-// commitStaged commits one staged packet dispatch routed to this lane. A shape the lane cannot
-// coalesce (any fragmentation, unparseable header) seals every open chain — its flow is unknown —
-// and rides the lane as an in-lane verbatim, still in transmission order.
-func (c *UDPCoalescer) commitStaged(sp stagedPacket) error {
-	if sp.fragAny {
-		c.sealAllOpen()
-		c.addVerbatim(sp.pkt)
-		return nil
-	}
-	var info parsedUDP
-	if !info.parseAt(sp.pkt, int(sp.ipHdrLen)) {
-		c.sealAllOpen()
-		c.addVerbatim(sp.pkt)
-		return nil
-	}
-	return c.commitParsed(sp.pkt, &info)
-}
-
-// commitParsed commits one parsed UDP packet. The caller (dispatch, via parseAt) supplies a
-// valid parse so the header is not re-walked here.
-func (c *UDPCoalescer) commitParsed(pkt []byte, info *parsedUDP) error {
-	// A zero-length UDP datagram (length == 8) is legal and must reach the TUN, but cannot be
-	// coalesced.
-	if info.payLen == 0 {
-		c.sealFlow(info.fk)
-		c.addVerbatim(pkt)
-		return nil
-	}
-	// Cached-slot fast path; see the TCPCoalescer equivalent.
-	var open *udpSlot
-	if last := c.lastSlot; last != nil && last.fk == info.fk {
-		open = last
-	} else {
-		open = c.openSlots[info.fk]
-	}
-	if open != nil {
-		if c.canAppend(open, pkt, info) {
-			if c.appendPayload(open, pkt, info) {
-				// Chain closed (short segment): stop extending it.
-				c.sealFlow(info.fk)
-			} else {
-				c.lastSlot = open
-			}
-			return nil
-		}
-		// Can't extend: evict it from openSlots and fall through to seed a
-		// fresh slot.
-		c.sealFlow(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.verbatim || s.numSeg == 1 {
-			// A slot that never grew is byte-identical to the packet it was
-			// seeded from; ship the original so its valid checksum rides the
-			// DATA_VALID path instead of paying a kernel software csum.
-			_, err = c.w.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
-	return first
-}
-
-// sealAllOpen closes every open coalesce chain. Called for unparseable packets: the flow key is
-// unknown, so any open chain could otherwise absorb later data and emit it ahead of this packet.
-func (c *UDPCoalescer) sealAllOpen() {
-	clear(c.openSlots)
-	c.lastSlot = nil
-}
-
-func (c *UDPCoalescer) addVerbatim(pkt []byte) {
-	s := c.take()
-	s.verbatim = true
-	s.rawPkt = pkt
-	c.slots = append(c.slots, s)
-}
-
-func (c *UDPCoalescer) seed(pkt []byte, info *parsedUDP) {
-	if info.hdrLen+info.payLen > udpCoalesceBufSize {
-		// Pathological shape that can't ride a superpacket; emit as-is. No chain for this flow can
-		// be open here (commitParsed evicts before seeding), so sealFlow is defense in depth
-		// against a stale cache entry absorbing later data.
-		c.sealFlow(info.fk)
-		c.addVerbatim(pkt)
-		return
-	}
-	s := c.take()
-	s.verbatim = false
-	// rawPkt serves the numSeg==1 fast path in Flush, is the header source for canAppend, and is
-	// the superpacket header flushSlot patches in place.
-	s.rawPkt = pkt
-	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.payIovs = append(s.payIovs[:0], pkt[info.hdrLen:info.hdrLen+info.payLen])
-	c.slots = append(c.slots, s)
-	c.openSlots[info.fk] = s
-	c.lastSlot = 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 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
-	}
-	// Header reads use rawPkt, which is never mutated before flush. A closed chain never reaches
-	// here; closing removes the slot from openSlots, the only path in.
-	if !s.isV6 && !ipv4CanCoalesceID(s.rawPkt, pkt, s.numSeg) {
-		return false
-	}
-	if !udpHeadersMatch(s.rawPkt[:s.hdrLen], pkt[:info.hdrLen], s.isV6, s.ipHdrLen) {
-		return false
-	}
-	return true
-}
-
-// appendPayload folds info's packet into s and reports whether the chain is now closed: kernel
-// UDP-GSO requires every segment but the last to be exactly gsoSize, so a short segment must be
-// the final one. The caller must deregister a closed slot from openSlots.
-func (c *UDPCoalescer) appendPayload(s *udpSlot, pkt []byte, info *parsedUDP) bool {
-	s.payIovs = append(s.payIovs, pkt[info.hdrLen:info.hdrLen+info.payLen])
-	s.numSeg++
-	s.totalPay += info.payLen
-	return info.payLen < s.gsoSize
-}
-
-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) {
-	// Reset every field, identity ones included; see TCPCoalescer.release.
-	clear(s.payIovs)
-	*s = udpSlot{payIovs: s.payIovs[:0]}
-	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 patches land in place in rawPkt; the
-// slot is released right after, so nothing re-reads the patched header.
-func (c *UDPCoalescer) flushSlot(s *udpSlot) error {
-	hdr := s.rawPkt[: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.w.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
-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
-	return bytes.Equal(a[udp:udp+4], b[udp:udp+4])
-}
@@ -1,72 +0,0 @@
-package batch
-
-import (
-	"testing"
-)
-
-// buildUDPv4BulkFlow returns n equal-size datagrams on one flow — the
-// steady state for single-flow QUIC bulk, the workload USO exists for.
-func buildUDPv4BulkFlow(n, payloadLen int) [][]byte {
-	pay := make([]byte, payloadLen)
-	pkts := make([][]byte, n)
-	for i := range pkts {
-		pkts[i] = buildUDPv4(40000, 443, pay)
-	}
-	return pkts
-}
-
-// buildUDPv4RunInterleaved mirrors buildTCPv4RunInterleaved: nFlows*perFlow
-// datagrams arriving in GRO-burst runs of runLen per flow.
-func buildUDPv4RunInterleaved(nFlows, perFlow, runLen, payloadLen int) [][]byte {
-	pay := make([]byte, payloadLen)
-	pkts := make([][]byte, 0, nFlows*perFlow)
-	for done := 0; done < perFlow; done += runLen {
-		for f := range nFlows {
-			sport := uint16(40000 + f)
-			for range runLen {
-				pkts = append(pkts, buildUDPv4(sport, 443, pay))
-			}
-		}
-	}
-	return pkts
-}
-
-// runUDPCommitBench drives UDPCoalescer.Commit over pkts batchSize at a
-// time, flushing between batches, and reports per-packet cost.
-func runUDPCommitBench(b *testing.B, pkts [][]byte, batchSize int) {
-	b.Helper()
-	c := newTestUDPCoalescer(b, 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)
-			}
-		}
-	}
-	_ = c.Flush()
-}
-
-// BenchmarkUDPCommitSingleFlow is the single-flow bulk steady state.
-func BenchmarkUDPCommitSingleFlow(b *testing.B) {
-	pkts := buildUDPv4BulkFlow(udpCoalesceMaxSegs, 1200)
-	runUDPCommitBench(b, pkts, udpCoalesceMaxSegs)
-}
-
-// BenchmarkUDPCommitInterleaved4 is the adversarial per-packet round-robin.
-func BenchmarkUDPCommitInterleaved4(b *testing.B) {
-	pkts := buildUDPv4RunInterleaved(4, udpCoalesceMaxSegs, 1, 1200)
-	runUDPCommitBench(b, pkts, len(pkts))
-}
-
-// BenchmarkUDPCommitRunInterleaved4 is 4 flows in GRO-burst runs of 16.
-func BenchmarkUDPCommitRunInterleaved4(b *testing.B) {
-	pkts := buildUDPv4RunInterleaved(4, udpCoalesceMaxSegs, 16, 1200)
-	runUDPCommitBench(b, pkts, len(pkts))
-}
@@ -1,536 +0,0 @@
-package batch
-
-import (
-	"bytes"
-	"encoding/binary"
-	"io"
-	"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
-}
-
-// newTestUDPCoalescer builds a coalescer over w and fails the test if w can't
-// do USO. See newTestTCPCoalescer.
-func newTestUDPCoalescer(tb testing.TB, w io.Writer) *UDPCoalescer {
-	tb.Helper()
-	c := NewUDPCoalescer(w)
-	if c == nil {
-		tb.Fatal("NewUDPCoalescer: writer does not support USO")
-	}
-	return c
-}
-
-// TestNewUDPCoalescerRefusesWhenGSOUnavailable mirrors the TCP precondition:
-// no USO, no coalescer.
-func TestNewUDPCoalescerRefusesWhenGSOUnavailable(t *testing.T) {
-	if c := NewUDPCoalescer(&fakeTunWriter{gsoEnabled: false}); c != nil {
-		t.Fatalf("want nil for a non-USO writer, got %v", c)
-	}
-	if c := NewUDPCoalescer(&plainOnlyWriter{}); c != nil {
-		t.Fatalf("want nil for a plain writer, got %v", c)
-	}
-}
-
-func TestUDPCoalescerNonUDPPassthrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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 := newTestUDPCoalescer(t, 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)
-	}
-	// A slot that never grew past one datagram flushes as a plain Write of
-	// the original packet bytes: the original (already valid) checksum
-	// ships via the DATA_VALID path, so the kernel does no csum work.
-	// WriteGSO is reserved for slots that actually coalesced (>=2 segs).
-	if len(w.writes) != 1 || len(w.gsoWrites) != 0 {
-		t.Fatalf("single-seg flush: writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	if !bytes.Equal(w.writes[0], pkt) {
-		t.Errorf("plain write not byte-identical to committed packet: got %d bytes want %d", len(w.writes[0]), len(pkt))
-	}
-}
-
-func TestUDPCoalescerCoalescesEqualSized(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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 := newTestUDPCoalescer(t, 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)
-	}
-	// The sealed 3-datagram chain is a real superpacket; the re-seed stays
-	// single-segment and flushes as a plain write of the original packet.
-	if len(w.gsoWrites) != 1 || len(w.writes) != 1 {
-		t.Fatalf("want 1 gso (sealed) + 1 plain (new seed), got gso=%d plain=%d", len(w.gsoWrites), len(w.writes))
-	}
-	if len(w.gsoWrites[0].pays) != 3 {
-		t.Errorf("super: want 3 pays, got %d", len(w.gsoWrites[0].pays))
-	}
-	if got, want := len(w.writes[0]), 20+8+1200; got != want {
-		t.Errorf("re-seed plain write len=%d want %d", got, want)
-	}
-}
-
-// A larger-than-gsoSize packet cannot extend the slot — it reseeds.
-func TestUDPCoalescerLargerThanSeedReseeds(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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)
-	}
-	// Both seeds stay single-segment → two plain writes in arrival order.
-	if len(w.writes) != 2 || len(w.gsoWrites) != 0 {
-		t.Fatalf("want 2 separate plain writes, got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	for i, want := range []int{20 + 8 + 800, 20 + 8 + 1200} {
-		if len(w.writes[i]) != want {
-			t.Errorf("write %d len=%d want %d", i, len(w.writes[i]), want)
-		}
-	}
-}
-
-// Different 5-tuples must not coalesce.
-func TestUDPCoalescerDifferentFlowsKeepSeparate(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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 := newTestUDPCoalescer(t, 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))
-	}
-}
-
-// Differing IP ECN codepoints must not coalesce: udpHeadersMatch compares
-// the full ToS byte (matching kernel GRO). A CE-marked datagram mid-run
-// seals the Not-ECT chain and reseeds; the trailing Not-ECT datagram
-// reseeds again. All three stay single-segment, so each ships as a plain
-// write of its original bytes, keeping its own codepoint.
-func TestUDPCoalescerDifferingECNReseeds(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, w)
-	pay := make([]byte, 800)
-	pkt0 := buildUDPv4(1000, 53, pay) // ECN=00 (Not-ECT)
-	pkt1 := buildUDPv4(1000, 53, pay)
-	pkt1[1] = 0x03                    // CE
-	pkt2 := buildUDPv4(1000, 53, pay) // ECN=00 again
-	for _, p := range [][]byte{pkt0, pkt1, pkt2} {
-		if err := c.Commit(p); err != nil {
-			t.Fatal(err)
-		}
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 3 || len(w.gsoWrites) != 0 {
-		t.Fatalf("want 3 separate plain writes (differing ECN), got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	wantECN := []byte{0x00, 0x03, 0x00}
-	for i, p := range w.writes {
-		if got := p[1] & 0x03; got != wantECN[i] {
-			t.Errorf("write %d ECN=%#x want %#x", i, got, wantECN[i])
-		}
-	}
-}
-
-// IPv6 path: same flow, equal-sized → coalesced.
-func TestUDPCoalescerIPv6Coalesces(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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: udpHeadersMatch compares the full ToS byte.
-func TestUDPCoalescerDSCPMismatchReseeds(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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)
-	}
-	// Both seeds stay single-segment → two plain writes, no gso.
-	if len(w.writes) != 2 || len(w.gsoWrites) != 0 {
-		t.Fatalf("want 2 separate plain writes (different DSCP), got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-}
-
-// Fragmented IPv4 must not be coalesced.
-func TestUDPCoalescerFragmentedIPv4PassesThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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))
-	}
-}
-
-// A zero-length UDP datagram (UDP length == 8, no payload) is legal and
-// must be delivered as a plain single datagram — never coalesced. Seeding
-// it into a GSO slot stores an empty payload iovec that panics WriteGSO
-// (index-out-of-range on &pay[0]); this is a remote DoS if we ever let it
-// reach the GSO path. Regression: must not panic and must be written.
-func TestUDPCoalescerZeroLengthPayloadPassesThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, w)
-	pkt := buildUDPv4(1000, 53, nil) // UDP length 8, zero payload
-	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("zero-length UDP must pass through plain, got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	if len(w.writes[0]) != len(pkt) {
-		t.Errorf("delivered %d bytes, want the whole %d-byte datagram", len(w.writes[0]), len(pkt))
-	}
-}
-
-// IPv6 zero-length UDP datagram: same verbatim contract as v4.
-func TestUDPCoalescerZeroLengthPayloadIPv6PassesThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, w)
-	pkt := buildUDPv6(1000, 53, nil) // UDP length 8, zero payload
-	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("zero-length IPv6 UDP must pass through plain, got writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	if len(w.writes[0]) != len(pkt) {
-		t.Errorf("delivered %d bytes, want the whole %d-byte datagram", len(w.writes[0]), len(pkt))
-	}
-}
-
-// A zero-length datagram arriving mid-flow must seal the open chain so the
-// datagram after it seeds a fresh superpacket *after* the empty one on the
-// wire — per-flow arrival order (full, empty, full) must be preserved.
-func TestUDPCoalescerZeroLengthMidFlowSealsAndPreservesOrder(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, w)
-	full := make([]byte, 800)
-	if err := c.Commit(buildUDPv4(1000, 53, full)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(1000, 53, nil)); err != nil { // zero-length
-		t.Fatal(err)
-	}
-	if err := c.Commit(buildUDPv4(1000, 53, full)); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	// The empty datagram sealed the first slot, so the trailing full packet
-	// can't join it. All three emit as plain writes (the two full datagrams
-	// stayed single-segment; the empty one is verbatim) in per-flow
-	// arrival order: full, empty, full.
-	if len(w.writes) != 3 || len(w.gsoWrites) != 0 {
-		t.Fatalf("want 3 plain writes, got gso=%d plain=%d", len(w.gsoWrites), len(w.writes))
-	}
-	for i, want := range []int{20 + 8 + 800, 20 + 8, 20 + 8 + 800} {
-		if len(w.writes[i]) != want {
-			t.Errorf("write %d len=%d want %d (order full, empty, full)", i, len(w.writes[i]), want)
-		}
-	}
-}
-
-// IPv4 with options is not admissible (we require IHL=5).
-func TestUDPCoalescerIPv4WithOptionsPassesThrough(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, 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))
-	}
-}
-
-// TestUDPCoalescerNonAtomicSequentialIDsCoalesce mirrors the TCP rule: DF
-// clear is fine as long as the IDs already run seed+1 per datagram, so
-// kernel USO's re-stamp reproduces them.
-func TestUDPCoalescerNonAtomicSequentialIDsCoalesce(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, w)
-	pay := make([]byte, 1200)
-
-	for i := range 2 {
-		pkt := buildUDPv4(40000, 443, pay)
-		setIPv4ID(pkt, uint16(40+i), false)
-		if err := c.Commit(pkt); err != nil {
-			t.Fatal(err)
-		}
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.gsoWrites) != 1 || len(w.gsoWrites[0].pays) != 2 {
-		t.Fatalf("sequential-ID DF=0 datagrams must coalesce: gso=%d", len(w.gsoWrites))
-	}
-}
-
-// TestUDPCoalescerNonAtomicIDGapReseeds: an ID jump on a DF=0 flow breaks
-// the chain; each datagram stays a single-segment slot and flushes as a
-// plain write that keeps its own (meaningful) ID.
-func TestUDPCoalescerNonAtomicIDGapReseeds(t *testing.T) {
-	w := &fakeTunWriter{gsoEnabled: true}
-	c := newTestUDPCoalescer(t, w)
-	pay := make([]byte, 1200)
-
-	p1 := buildUDPv4(40000, 443, pay)
-	setIPv4ID(p1, 40, false)
-	p2 := buildUDPv4(40000, 443, pay)
-	setIPv4ID(p2, 50, false)
-
-	if err := c.Commit(p1); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Commit(p2); err != nil {
-		t.Fatal(err)
-	}
-	if err := c.Flush(); err != nil {
-		t.Fatal(err)
-	}
-	if len(w.writes) != 2 || len(w.gsoWrites) != 0 {
-		t.Fatalf("ID gap on DF=0 must reseed: writes=%d gso=%d", len(w.writes), len(w.gsoWrites))
-	}
-	for i, want := range []uint16{40, 50} {
-		if id := binary.BigEndian.Uint16(w.writes[i][4:6]); id != want {
-			t.Errorf("write %d: ID=%d want %d (must be preserved)", i, id, want)
-		}
-	}
-}
@@ -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)
-}
@@ -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
@@ -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)
-}
@@ -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
@@ -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)
-}
@@ -1,232 +0,0 @@
-package checksum
-
-import (
-	"fmt"
-	"math/rand/v2"
-	"testing"
-
-	gvisorchecksum "gvisor.dev/gvisor/pkg/tcpip/checksum"
-)
-
-// archImpl names one checksum function under test. The per-arch
-// export_*_test.go files enumerate the hand-written implementations so the
-// suite compares each one against gvisor directly, regardless of which one
-// the public Checksum dispatches to on the running CPU. Testing only the
-// dispatcher was tautological wherever it resolved to the gvisor fallback
-// (non-AVX2 amd64, fallback architectures) — gvisor compared with itself,
-// assembly untested, suite green.
-type archImpl struct {
-	name      string
-	fn        func([]byte, uint16) uint16
-	available bool
-}
-
-// implsUnderTest is the public dispatcher plus every arch implementation.
-func implsUnderTest() []archImpl {
-	return append([]archImpl{{name: "dispatch", fn: Checksum, available: true}}, archImpls...)
-}
-
-// requireAvailable skips loudly when the running CPU can't execute an
-// implementation — visible in test output, unlike the old silent tautology.
-func requireAvailable(t *testing.T, impl archImpl) {
-	t.Helper()
-	if !impl.available {
-		t.Skipf("%s not supported on this CPU; its assembly is NOT tested in this run", impl.name)
-	}
-}
-
-// TestChecksumMatchesGvisor walks lengths from 0 to 4096, with several initial
-// seeds and a handful of starting alignments, asserting that each local
-// implementation matches gvisor's reference bit-for-bit.
-func TestChecksumMatchesGvisor(t *testing.T) {
-	for _, impl := range implsUnderTest() {
-		t.Run(impl.name, func(t *testing.T) {
-			requireAvailable(t, impl)
-			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 := impl.fn(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 _, impl := range implsUnderTest() {
-		t.Run(impl.name, func(t *testing.T) {
-			requireAvailable(t, impl)
-			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 := impl.fn(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) {
-	for _, impl := range implsUnderTest() {
-		t.Run(impl.name, func(t *testing.T) {
-			requireAvailable(t, impl)
-			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 := impl.fn(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)
-			}
-		})
-	}
-}
@@ -1,11 +0,0 @@
-package checksum
-
-// archImpls exposes every hand-written implementation on this architecture
-// so the tests exercise them directly, independent of what the public
-// Checksum dispatches to on the running CPU. Without this, running the
-// suite on a non-AVX2 machine compared gvisor against itself and left the
-// assembly untested — silently. available=false makes the test skip loudly
-// instead.
-var archImpls = []archImpl{
-	{name: "avx2", fn: checksumAVX2, available: hasAVX2},
-}
@@ -1,8 +0,0 @@
-package checksum
-
-// archImpls exposes every hand-written implementation on this architecture
-// for direct testing; see export_amd64_test.go for the rationale. NEON is
-// mandatory in armv8, so it is always available.
-var archImpls = []archImpl{
-	{name: "neon", fn: checksumNEON, available: true},
-}
@@ -1,7 +0,0 @@
-//go:build !amd64 && !arm64
-
-package checksum
-
-// No hand-written implementations on this architecture; the dispatcher is
-// pure gvisor and there is nothing separate to test.
-var archImpls []archImpl
@@ -4,25 +4,15 @@ 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
-	// Queues returns the device's packet queues, opening additional ones as
-	// needed until there are n. Platforms without multiqueue support return
-	// their single queue regardless of n, so callers must size reader loops
-	// to len(result), not n; implementations never return more than n. An
-	// error means a queue that should have opened could not; the caller owns
-	// cleanup via Close. Called once, during interface activation.
-	Queues(n int) ([]tio.Queue, error)
+	SupportsMultiqueue() bool
+	NewMultiQueueReader() (io.ReadWriteCloser, error)
 }
@@ -3,9 +3,10 @@
 package overlaytest

 import (
+	"errors"
+	"io"
 	"net/netip"

-	"github.com/slackhq/nebula/overlay/tio"
 	"github.com/slackhq/nebula/routing"
 )

@@ -30,16 +31,20 @@ 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) {
 	return 0, nil
 }

-func (NoopTun) Queues(int) ([]tio.Queue, error) {
-	return []tio.Queue{NoopTun{}}, nil
+func (NoopTun) SupportsMultiqueue() bool {
+	return false
+}
+
+func (NoopTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, errors.New("unsupported")
 }

 func (NoopTun) Close() error {
@@ -1,44 +0,0 @@
-//go:build linux && !android
-// +build linux,!android
-
-package tio
-
-import (
-	"os"
-
-	"golang.org/x/sys/unix"
-)
-
-// blockOn parks the calling goroutine until fd is ready or shutdownFd signals teardown.
-// (events is POLLIN for reads, POLLOUT for writes)
-// It builds the pollfd array on the stack every call, so concurrent callers on the same Queue never share Revents storage.
-//
-// Returns os.ErrClosed when shutdown was signaled (POLLIN on shutdownFd)
-// or either fd reported a problem condition (POLLHUP|POLLNVAL|POLLERR).
-func blockOn(fd, shutdownFd int32, events int16) error {
-	const problemFlags = unix.POLLHUP | unix.POLLNVAL | unix.POLLERR
-	pfds := [2]unix.PollFd{
-		{Fd: fd, Events: events},
-		{Fd: shutdownFd, Events: unix.POLLIN},
-	}
-	var err error
-	for {
-		_, err = unix.Poll(pfds[:], -1)
-		if err != unix.EINTR {
-			break
-		}
-	}
-	tunEvents := pfds[0].Revents
-	shutdownEvents := pfds[1].Revents
-	// Check err before trusting the potentially bogus bits we just got.
-	if err != nil {
-		return err
-	}
-	if shutdownEvents&(unix.POLLIN|problemFlags) != 0 {
-		return os.ErrClosed
-	}
-	if tunEvents&problemFlags != 0 {
-		return os.ErrClosed
-	}
-	return nil
-}
@@ -1,101 +0,0 @@
-//go:build linux && !android
-// +build linux,!android
-
-package tio
-
-import (
-	"encoding/binary"
-	"errors"
-	"fmt"
-	"log/slog"
-	"sync/atomic"
-
-	"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
-	closed     atomic.Bool
-	// l is handed to each queue for its bad-vnet-header drop logging.
-	l *slog.Logger
-}
-
-// NewOffloadQueueSet creates a QueueSet that uses virtio_net_hdr to do TSO segmentation.
-// usoEnabled tells downstream queues whether the kernel agreed to deliver/accept GSO_UDP_L4 superpackets.
-func NewOffloadQueueSet(usoEnabled bool, l *slog.Logger) (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,
-		l:          l,
-	}
-
-	return out, nil
-}
-
-func (c *offloadQueueSet) Queues() []Queue {
-	return c.pqi
-}
-
-func (c *offloadQueueSet) Add(fd int) error {
-	if c.closed.Load() {
-		return errors.New("queue set already closed")
-	}
-	x, err := newOffload(fd, c.shutdownFd, c.usoEnabled, c.l)
-	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 {
-	if c.closed.Swap(true) {
-		return nil
-	}
-
-	errs := []error{}
-
-	// Signal all readers blocked in poll to wake up and exit.
-	// They observe POLLIN on the shutdown eventfd and return os.ErrClosed.
-	if err := c.wakeForShutdown(); err != nil {
-		errs = append(errs, err)
-	}
-
-	// Close the per-queue tun fds; this also unblocks any in-flight reads.
-	for _, x := range c.pq {
-		if err := x.Close(); err != nil {
-			errs = append(errs, err)
-		}
-	}
-
-	// Close the shutdown eventfd last: every reader's pollfd set references it,
-	// so it must outlive the wake + per-queue teardown above.
-	if err := unix.Close(c.shutdownFd); err != nil {
-		errs = append(errs, err)
-	}
-	c.shutdownFd = -1
-
-	return errors.Join(errs...)
-}
@@ -1,91 +0,0 @@
-//go:build linux && !android
-// +build linux,!android
-
-package tio
-
-import (
-	"encoding/binary"
-	"errors"
-	"fmt"
-	"sync/atomic"
-
-	"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
-	closed     atomic.Bool
-}
-
-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 {
-	if c.closed.Load() {
-		return errors.New("queue set already closed")
-	}
-	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 {
-	if c.closed.Swap(true) {
-		return nil
-	}
-
-	errs := []error{}
-
-	// Signal all readers blocked in poll to wake up and exit.
-	// They observe POLLIN on the shutdown eventfd and return os.ErrClosed.
-	if err := c.wakeForShutdown(); err != nil {
-		errs = append(errs, err)
-	}
-
-	// Close the per-queue tun fds; this also unblocks any in-flight reads.
-	for _, x := range c.pq {
-		if err := x.Close(); err != nil {
-			errs = append(errs, err)
-		}
-	}
-
-	// Close the shutdown eventfd last: every reader's pollfd set references it,
-	// so it must outlive the wake + per-queue teardown above.
-	if err := unix.Close(c.shutdownFd); err != nil {
-		errs = append(errs, err)
-	}
-	c.shutdownFd = -1
-
-	return errors.Join(errs...)
-}
@@ -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)
-		}
-	}
-}
@@ -1,16 +0,0 @@
-//go:build !linux || android
-
-package tio
-
-import "fmt"
-
-func protoFromGSOType(_ uint8) (GSOProto, error) {
-	return 0, fmt.Errorf("GSO unsupported")
-}
-
-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)
-}
@@ -1,49 +0,0 @@
-package tio
-
-import "io"
-
-// singleQueue adapts a legacy one-datagram-per-Read source into a Queue.
-// Read fills a private scratch buffer and returns exactly one Packet whose
-// Bytes borrow from that buffer, valid only until the next Read, per the Queue contract.
-// Single-reader like every Queue; Write is exactly as safe for concurrent use as the underlying source's Write.
-type singleQueue struct {
-	rw     io.ReadWriter
-	closer io.Closer // nil: Close is a no-op (the source is shared and owned elsewhere)
-	buf    []byte
-	ret    [1]Packet
-}
-
-// NewSingleQueue wraps a one-datagram-per-Read ReadWriteCloser (a legacy tun device) into a Queue.
-// bufSize is the per-queue read scratch size and must be at least the largest datagram the source can return.
-// Close closes rwc.
-func NewSingleQueue(rwc io.ReadWriteCloser, bufSize int) Queue {
-	return &singleQueue{rw: rwc, closer: rwc, buf: make([]byte, bufSize)}
-}
-
-// NewSingleQueueNoClose is NewSingleQueue for a source owned by someone else,
-// e.g. several queues sharing one device. Close on the returned Queue is a
-// no-op so one queue can't tear the shared source out from under its
-// siblings; the owner remains responsible for closing the source itself.
-func NewSingleQueueNoClose(rw io.ReadWriter, bufSize int) Queue {
-	return &singleQueue{rw: rw, buf: make([]byte, bufSize)}
-}
-
-func (q *singleQueue) Read() ([]Packet, error) {
-	n, err := q.rw.Read(q.buf)
-	if err != nil {
-		return nil, err
-	}
-	q.ret[0] = Packet{Bytes: q.buf[:n]}
-	return q.ret[:], nil
-}
-
-func (q *singleQueue) Write(p []byte) (int, error) {
-	return q.rw.Write(p)
-}
-
-func (q *singleQueue) Close() error {
-	if q.closer == nil {
-		return nil
-	}
-	return q.closer.Close()
-}
@@ -1,147 +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.
-type Capabilities struct {
-	// TSO means the FD was opened with IFF_VNET_HDR and the kernel agreed to TUN_F_TSO4|TSO6,
-	// and 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.
-// Concurrency contract: a single read goroutine drives Read; plain Write is safe for concurrent callers;
-// WriteGSO (on Queues that implement GSOWriter) is single-writer per queue.
-//
-// Close on an individual Queue does NOT unblock a Read parked in poll — closing an fd
-// never wakes its pollers. Orderly teardown goes through the owning QueueSet's Close,
-// which first signals a shared shutdown eventfd every reader polls alongside its own fd.
-// That eventfd is a set-wide kill switch: once signaled, every Queue in the set returns
-// os.ErrClosed from Read, so it cannot be used to stop a single Queue.
-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.
-	// A Packet may carry a GSO/USO superpacket (see GSOInfo)
-	// Single-reader only: not safe for concurrent Reads (it reuses per-queue rx scratch each call).
-	Read() ([]Packet, error)
-
-	// Write emits a single packet on the plaintext (outside→inside) delivery path.
-	// Safe for concurrent use.
-	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 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 needs the data to outlive the borrowed-slice contract.
-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 negotiate 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.
-type CapsProvider interface {
-	Capabilities() 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 (
-	GSOProtoUnknown GSOProto = iota
-	GSOProtoTCP
-	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 must be 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) for the per-protocol negotiated capability:
-// USO may not have been negotiated even when TSO was.
-type GSOWriter interface {
-	io.Writer
-	CapsProvider
-	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`.
-func SupportsGSO(w io.Writer, want GSOProto) (GSOWriter, bool) {
-	gw, ok := w.(GSOWriter)
-	if !ok {
-		return nil, false
-	}
-	caps := gw.Capabilities()
-	switch want {
-	case GSOProtoTCP:
-		return gw, caps.TSO
-	case GSOProtoUDP:
-		return gw, caps.USO
-	default:
-		return gw, false
-	}
-}
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Wade Simmons	992e36b678	v1.11.1 (#1854 ) Prepare the v1.11.1 CHANGELOG updates	2026-08-21 15:23:25 -04:00
Nate Brown	5d7c8c905b	release: retry the STS assume until the secret key survives Windows (#1856 )	2026-08-21 11:03:53 -05:00
Wade Simmonsandsn0w	c2ad75e459	cmd/ca: prevent out-of-memory on 32bit systems (#1834 ) (#1852 ) (cherry picked from commit `6fcb926334`) Co-authored-by: sn0w <me@sn0w.re>	2026-08-20 16:52:50 -04:00
Wade SimmonsandNate Brown	0a916b1d4b	parseV6: only walk real ipv6 extension headers, fail closed on unknown protocols (#1840 ) (#1853 ) (cherry picked from commit `49e35d1283`) Co-authored-by: Nate Brown <nbrown.us@gmail.com>	2026-08-20 16:52:36 -04:00
Wade SimmonsandNate Brown	33abaf95cd	Enforce outbound message counter limits to prevent nonce reuse (#1841 ) (#1850 ) (cherry picked from commit `f15d10fc54`) Co-authored-by: Nate Brown <nbrown.us@gmail.com>	2026-08-20 14:24:11 -04:00
Wade Simmons Jay R. Wren Claude	20c68ef3c4	Drop dependency on github.com/cyberdelia/go-metrics-graphite (#1832 ) (#1849 ) The go-metrics-graphite package has been unmaintained for 10+ years, which is a packaging and supply-chain concern for downstream distributors (see #1831). Nebula only used its Config struct and Once() entrypoint, so inline just those (~65 lines) into a local graphite.go, preserving the upstream BSD-2-Clause copyright notice, and remove the dependency. Fixes #1831 (cherry picked from commit `28d82f7b8a`) Co-authored-by: Jay R. Wren <jay.wren@slack-corp.com> Co-authored-by: Claude <svc-devxp-claude@slack-corp.com>	2026-08-20 14:23:45 -04:00
Wade SimmonsandNate Brown	f46abae87e	Take Apple signing credentials from Secrets Manager (#1833 ) (#1848 ) (cherry picked from commit `e7b4e094b9`) Co-authored-by: Nate Brown <nbrown.us@gmail.com>	2026-08-20 07:52:12 -04:00
Wade SimmonsandJohn Maguire	ae688d038d	Tolerate ErrDumpInterrupted when listing tun addresses (#1842 ) Backport from #1835 to release 1.11 ## What Since the bump to netlink v1.3.0, `netlink.AddrList` returns `ErrDumpInterrupted` ("results may be incomplete or inconsistent") when the kernel sets `NLM_F_DUMP_INTR` on an address dump. `addIPs` treats any error from `AddrList` as fatal, so a transient interrupted dump aborts startup: ``` failed to start nebula: failed to get tun address list: results may be incomplete or inconsistent ``` Before v1.3.0, the pinned netlink release had no `NLM_F_DUMP_INTR` handling at all and silently returned partial results, so this condition was previously invisible. ## Root cause The dump is racing nebula's own setup. `RTM_GETADDR` dumps addresses for the whole system, and the kernel flags the dump as interrupted if any address changes between recvmsg batches. When the cert contains an IPv6 network, the `AddrReplace` a few lines above returns while the new address is still tentative; the kernel's DAD worker flips it to preferred asynchronously ~100-400us later, and that flip lands inside the immediately-following dump. The race is entirely self-contained - no concurrent restart or interface churn is required, and the hit rate scales with how many addresses are on the host (more dump batches = wider window). Reproduced with a standalone tool replaying this exact netlink sequence on a host with ~80 addresses: an IPv6 /80 alone interrupts 10/200 cycles and v4+v6 together 16/200, while IPv4-only runs 0/800. `ip -ts monitor addr` shows the tentative add and the async flag-clear as two events during the dump window. Hosts with DAD disabled (`net.ipv6.conf.all.accept_dad=0`, e.g. LXC containers) never reproduce, confirming the flip is the trigger. Observed in the wild as dnclient package upgrades reliably failing their post-install restart (systemd start timeout, package left half-configured). ## How Treat `ErrDumpInterrupted` as success with a warning. netlink still returns the partial result set alongside the error, and this call site only uses the list to prune addresses that are not in the certs; a missed stale address survives until the next reload, which is strictly better than failing startup. All cert addresses were already applied via `AddrReplace` above. Co-authored-by: John Maguire <john@defined.net>	2026-08-19 11:35:06 -04:00