skeleton to handle other tunless packets

Newly signed P256 based certificates will have their signature clamped to the low-s form.

Update CHANGELOG.md

CHANGELOG.md

@@ -7,6 +7,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.10.3] - 2026-02-06
+
+### Security
+
+- Fix an issue where blocklist bypass is possible when using curve P256 since the signature can have 2 valid representations.
+  Both fingerprint representations will be tested against the blocklist.
+  Any newly issued P256 based certificates will have their signature clamped to the low-s form.
+  Nebula will assert the low-s signature form when validating certificates in a future version. [GHSA-69x3-g4r3-p962](https://github.com/slackhq/nebula/security/advisories/GHSA-69x3-g4r3-p962)
+
+### Changed
+
+- Improve error reporting if nebula fails to start due to a tun device naming issue. (#1588)
+
 ## [1.10.2] - 2026-01-21
 
 ### Fixed
@@ -775,7 +788,8 @@ created.)
 
 - Initial public release.
 
-[Unreleased]: https://github.com/slackhq/nebula/compare/v1.10.2...HEAD
+[Unreleased]: https://github.com/slackhq/nebula/compare/v1.10.3...HEAD
+[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
 [1.10.0]: https://github.com/slackhq/nebula/releases/tag/v1.10.0

cert/ca_pool.go

@@ -141,10 +141,23 @@ func (ncp *CAPool) VerifyCertificate(now time.Time, c Certificate) (*CachedCerti
 		return nil, err
 	}
 
+	// Pre nebula v1.10.3 could generate signatures in either high or low s form and validation
+	// of signatures allowed for either. Nebula v1.10.3 and beyond clamps signature generation to low-s form
+	// but validation still allows for either. Since a change in the signature bytes affects the fingerprint, we
+	// need to test both forms until such a time comes that we enforce low-s form on signature validation.
+	fp2, err := CalculateAlternateFingerprint(c)
+	if err != nil {
+		return nil, fmt.Errorf("could not calculate alternate fingerprint to verify: %w", err)
+	}
+	if fp2 != "" && ncp.IsBlocklisted(fp2) {
+		return nil, ErrBlockListed
+	}
+
 	cc := CachedCertificate{
 		Certificate:       c,
 		InvertedGroups:    make(map[string]struct{}),
 		Fingerprint:       fp,
+		fingerprint2:      fp2,
 		signerFingerprint: signer.Fingerprint,
 	}
 
@@ -158,6 +171,11 @@ func (ncp *CAPool) VerifyCertificate(now time.Time, c Certificate) (*CachedCerti
 // VerifyCachedCertificate is the same as VerifyCertificate other than it operates on a pre-verified structure and
 // is a cheaper operation to perform as a result.
 func (ncp *CAPool) VerifyCachedCertificate(now time.Time, c *CachedCertificate) error {
+	// Check any available alternate fingerprint forms for this certificate, re P256 high-s/low-s
+	if c.fingerprint2 != "" && ncp.IsBlocklisted(c.fingerprint2) {
+		return ErrBlockListed
+	}
+
 	_, err := ncp.verify(c.Certificate, now, c.Fingerprint, c.signerFingerprint)
 	return err
 }

cert/ca_pool_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/slackhq/nebula/cert/p256"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -170,6 +171,15 @@ func TestCertificateV1_VerifyP256(t *testing.T) {
 	_, err = caPool.VerifyCertificate(time.Now(), c)
 	require.EqualError(t, err, "certificate is in the block list")
 
+	// Create a copy of the cert and swap to the alternate form for the signature
+	nc := c.Copy()
+	b, err := p256.Swap(c.Signature())
+	require.NoError(t, err)
+	require.NoError(t, nc.(*certificateV1).setSignature(b))
+
+	_, err = caPool.VerifyCertificate(time.Now(), nc)
+	require.EqualError(t, err, "certificate is in the block list")
+
 	caPool.ResetCertBlocklist()
 	_, err = caPool.VerifyCertificate(time.Now(), c)
 	require.NoError(t, err)
@@ -187,7 +197,7 @@ func TestCertificateV1_VerifyP256(t *testing.T) {
 	require.NoError(t, err)
 
 	caPool = NewCAPool()
-	b, err := caPool.AddCAFromPEM(caPem)
+	b, err = caPool.AddCAFromPEM(caPem)
 	require.NoError(t, err)
 	assert.Empty(t, b)
 
@@ -196,7 +206,17 @@ func TestCertificateV1_VerifyP256(t *testing.T) {
 	})
 
 	c, _, _, _ = NewTestCert(Version1, Curve_P256, ca, caKey, "test", time.Now(), time.Now().Add(5*time.Minute), nil, nil, []string{"test1"})
-	_, err = caPool.VerifyCertificate(time.Now(), c)
+	cc, err := caPool.VerifyCertificate(time.Now(), c)
+	require.NoError(t, err)
+
+	// Reset the blocklist and block the alternate form fingerprint
+	caPool.ResetCertBlocklist()
+	caPool.BlocklistFingerprint(cc.fingerprint2)
+	err = caPool.VerifyCachedCertificate(time.Now(), cc)
+	require.EqualError(t, err, "certificate is in the block list")
+
+	caPool.ResetCertBlocklist()
+	err = caPool.VerifyCachedCertificate(time.Now(), cc)
 	require.NoError(t, err)
 }
 
@@ -394,6 +414,15 @@ func TestCertificateV2_VerifyP256(t *testing.T) {
 	_, err = caPool.VerifyCertificate(time.Now(), c)
 	require.EqualError(t, err, "certificate is in the block list")
 
+	// Create a copy of the cert and swap to the alternate form for the signature
+	nc := c.Copy()
+	b, err := p256.Swap(c.Signature())
+	require.NoError(t, err)
+	require.NoError(t, nc.(*certificateV2).setSignature(b))
+
+	_, err = caPool.VerifyCertificate(time.Now(), nc)
+	require.EqualError(t, err, "certificate is in the block list")
+
 	caPool.ResetCertBlocklist()
 	_, err = caPool.VerifyCertificate(time.Now(), c)
 	require.NoError(t, err)
@@ -411,7 +440,7 @@ func TestCertificateV2_VerifyP256(t *testing.T) {
 	require.NoError(t, err)
 
 	caPool = NewCAPool()
-	b, err := caPool.AddCAFromPEM(caPem)
+	b, err = caPool.AddCAFromPEM(caPem)
 	require.NoError(t, err)
 	assert.Empty(t, b)
 
@@ -420,7 +449,17 @@ func TestCertificateV2_VerifyP256(t *testing.T) {
 	})
 
 	c, _, _, _ = NewTestCert(Version2, Curve_P256, ca, caKey, "test", time.Now(), time.Now().Add(5*time.Minute), nil, nil, []string{"test1"})
-	_, err = caPool.VerifyCertificate(time.Now(), c)
+	cc, err := caPool.VerifyCertificate(time.Now(), c)
+	require.NoError(t, err)
+
+	// Reset the blocklist and block the alternate form fingerprint
+	caPool.ResetCertBlocklist()
+	caPool.BlocklistFingerprint(cc.fingerprint2)
+	err = caPool.VerifyCachedCertificate(time.Now(), cc)
+	require.EqualError(t, err, "certificate is in the block list")
+
+	caPool.ResetCertBlocklist()
+	err = caPool.VerifyCachedCertificate(time.Now(), cc)
 	require.NoError(t, err)
 }
 

cert/cert.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"net/netip"
 	"time"
+
+	"github.com/slackhq/nebula/cert/p256"
 )
 
 type Version uint8
@@ -110,6 +112,9 @@ type CachedCertificate struct {
 	InvertedGroups    map[string]struct{}
 	Fingerprint       string
 	signerFingerprint string
+
+	// A place to store a 2nd fingerprint if the certificate could have one, such as with P256
+	fingerprint2 string
 }
 
 func (cc *CachedCertificate) String() string {
@@ -152,3 +157,31 @@ func Recombine(v Version, rawCertBytes, publicKey []byte, curve Curve) (Certific
 
 	return c, nil
 }
+
+// CalculateAlternateFingerprint calculates a 2nd fingerprint representation for P256 certificates
+// CAPool blocklist testing through `VerifyCertificate` and `VerifyCachedCertificate` automatically performs this step.
+func CalculateAlternateFingerprint(c Certificate) (string, error) {
+	if c.Curve() != Curve_P256 {
+		return "", nil
+	}
+
+	nc := c.Copy()
+	b, err := p256.Swap(nc.Signature())
+	if err != nil {
+		return "", err
+	}
+
+	switch v := nc.(type) {
+	case *certificateV1:
+		err = v.setSignature(b)
+	case *certificateV2:
+		err = v.setSignature(b)
+	default:
+		return "", ErrUnknownVersion
+	}
+
+	if err != nil {
+		return "", err
+	}
+	return nc.Fingerprint()
+}

cert/p256/p256.go

@@ -0,0 +1,122 @@
+package p256
+
+import (
+	"crypto/elliptic"
+	"errors"
+	"math/big"
+
+	"filippo.io/bigmod"
+
+	"golang.org/x/crypto/cryptobyte"
+	"golang.org/x/crypto/cryptobyte/asn1"
+)
+
+var halfN = new(big.Int).Rsh(elliptic.P256().Params().N, 1)
+var nMod *bigmod.Modulus
+
+func init() {
+	n, err := bigmod.NewModulus(elliptic.P256().Params().N.Bytes())
+	if err != nil {
+		panic(err)
+	}
+	nMod = n
+}
+
+func IsNormalized(sig []byte) (bool, error) {
+	r, s, err := parseSignature(sig)
+	if err != nil {
+		return false, err
+	}
+	return checkLowS(r, s), nil
+}
+
+func checkLowS(_, s []byte) bool {
+	bigS := new(big.Int).SetBytes(s)
+	// Check if S <= (N/2), because we want to include the midpoint in the set of low-s
+	return bigS.Cmp(halfN) <= 0
+}
+
+func swap(r, s []byte) ([]byte, []byte, error) {
+	var err error
+	bigS, err := bigmod.NewNat().SetBytes(s, nMod)
+	if err != nil {
+		return nil, nil, err
+	}
+	sNormalized := nMod.Nat().Sub(bigS, nMod)
+
+	return r, sNormalized.Bytes(nMod), nil
+}
+
+func Normalize(sig []byte) ([]byte, error) {
+	r, s, err := parseSignature(sig)
+	if err != nil {
+		return nil, err
+	}
+
+	if checkLowS(r, s) {
+		return sig, nil
+	}
+
+	newR, newS, err := swap(r, s)
+	if err != nil {
+		return nil, err
+	}
+
+	return encodeSignature(newR, newS)
+}
+
+// Swap will change sig between its current form to the opposite high or low form.
+func Swap(sig []byte) ([]byte, error) {
+	r, s, err := parseSignature(sig)
+	if err != nil {
+		return nil, err
+	}
+
+	newR, newS, err := swap(r, s)
+	if err != nil {
+		return nil, err
+	}
+
+	return encodeSignature(newR, newS)
+}
+
+// parseSignature taken exactly from crypto/ecdsa/ecdsa.go
+func parseSignature(sig []byte) (r, s []byte, err error) {
+	var inner cryptobyte.String
+	input := cryptobyte.String(sig)
+	if !input.ReadASN1(&inner, asn1.SEQUENCE) ||
+		!input.Empty() ||
+		!inner.ReadASN1Integer(&r) ||
+		!inner.ReadASN1Integer(&s) ||
+		!inner.Empty() {
+		return nil, nil, errors.New("invalid ASN.1")
+	}
+	return r, s, nil
+}
+
+func encodeSignature(r, s []byte) ([]byte, error) {
+	var b cryptobyte.Builder
+	b.AddASN1(asn1.SEQUENCE, func(b *cryptobyte.Builder) {
+		addASN1IntBytes(b, r)
+		addASN1IntBytes(b, s)
+	})
+	return b.Bytes()
+}
+
+// addASN1IntBytes encodes in ASN.1 a positive integer represented as
+// a big-endian byte slice with zero or more leading zeroes.
+func addASN1IntBytes(b *cryptobyte.Builder, bytes []byte) {
+	for len(bytes) > 0 && bytes[0] == 0 {
+		bytes = bytes[1:]
+	}
+	if len(bytes) == 0 {
+		b.SetError(errors.New("invalid integer"))
+		return
+	}
+	b.AddASN1(asn1.INTEGER, func(c *cryptobyte.Builder) {
+		if bytes[0]&0x80 != 0 {
+			c.AddUint8(0)
+		}
+		c.AddBytes(bytes)
+	})
+}

cert/p256/p256_test.go

@@ -0,0 +1,28 @@
+package p256
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFlipping(t *testing.T) {
+	priv, err1 := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err1)
+
+	out, err := ecdsa.SignASN1(rand.Reader, priv, []byte("big chungus"))
+	require.NoError(t, err)
+
+	r, s, err := parseSignature(out)
+	require.NoError(t, err)
+
+	r, s1, err := swap(r, s)
+	require.NoError(t, err)
+	r, s2, err := swap(r, s1)
+	require.NoError(t, err)
+	require.Equal(t, s, s2)
+	require.NotEqual(t, s, s1)
+}

cert/sign.go

@@ -9,6 +9,8 @@ import (
 	"fmt"
 	"net/netip"
 	"time"
+
+	"github.com/slackhq/nebula/cert/p256"
 )
 
 // TBSCertificate represents a certificate intended to be signed.
@@ -126,6 +128,13 @@ func (t *TBSCertificate) SignWith(signer Certificate, curve Curve, sp SignerLamb
 		return nil, err
 	}
 
+	if curve == Curve_P256 {
+		sig, err = p256.Normalize(sig)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	err = c.setSignature(sig)
 	if err != nil {
 		return nil, err

cert/sign_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/slackhq/nebula/cert/p256"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -89,3 +90,48 @@ func TestCertificateV1_SignP256(t *testing.T) {
 	require.NoError(t, err)
 	assert.NotNil(t, uc)
 }
+
+func TestCertificate_SignP256_AlwaysNormalized(t *testing.T) {
+	before := time.Now().Add(time.Second * -60).Round(time.Second)
+	after := time.Now().Add(time.Second * 60).Round(time.Second)
+	pubKey := []byte("01234567890abcedfghij1234567890ab1234567890abcedfghij1234567890ab")
+
+	tbs := TBSCertificate{
+		Version: Version1,
+		Name:    "testing",
+		Networks: []netip.Prefix{
+			mustParsePrefixUnmapped("10.1.1.1/24"),
+			mustParsePrefixUnmapped("10.1.1.2/16"),
+		},
+		UnsafeNetworks: []netip.Prefix{
+			mustParsePrefixUnmapped("9.1.1.2/24"),
+			mustParsePrefixUnmapped("9.1.1.3/16"),
+		},
+		Groups:    []string{"test-group1", "test-group2", "test-group3"},
+		NotBefore: before,
+		NotAfter:  after,
+		PublicKey: pubKey,
+		IsCA:      true,
+		Curve:     Curve_P256,
+	}
+
+	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	pub := elliptic.Marshal(elliptic.P256(), priv.PublicKey.X, priv.PublicKey.Y)
+	rawPriv := priv.D.FillBytes(make([]byte, 32))
+
+	for i := 0; i < 1000; i++ {
+		if i&1 == 1 {
+			tbs.Version = Version1
+		} else {
+			tbs.Version = Version2
+		}
+		c, err := tbs.Sign(nil, Curve_P256, rawPriv)
+		require.NoError(t, err)
+		assert.NotNil(t, c)
+		assert.True(t, c.CheckSignature(pub))
+		normie, err := p256.IsNormalized(c.Signature())
+		require.NoError(t, err)
+		assert.True(t, normie)
+	}
+}

cmd/nebula-cert/test_freebsd.go

@@ -1,4 +0,0 @@
-package main
-
-const NoSuchFileError = "no such file or directory"
-const NoSuchDirError = "no such file or directory"

cmd/nebula-cert/test_openbsd.go

@@ -1,4 +0,0 @@
-package main
-
-const NoSuchFileError = "no such file or directory"
-const NoSuchDirError = "no such file or directory"

connection_manager_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/test"
-	"github.com/slackhq/nebula/test/device"
 	"github.com/slackhq/nebula/udp"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -53,7 +52,7 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 	lh := newTestLighthouse()
 	ifce := &Interface{
 		hostMap:          hostMap,
-		inside:           &device.NoopTun{},
+		inside:           &test.NoopTun{},
 		outside:          &udp.NoopConn{},
 		firewall:         &Firewall{},
 		lightHouse:       lh,
@@ -136,7 +135,7 @@ func Test_NewConnectionManagerTest2(t *testing.T) {
 	lh := newTestLighthouse()
 	ifce := &Interface{
 		hostMap:          hostMap,
-		inside:           &device.NoopTun{},
+		inside:           &test.NoopTun{},
 		outside:          &udp.NoopConn{},
 		firewall:         &Firewall{},
 		lightHouse:       lh,
@@ -221,7 +220,7 @@ func Test_NewConnectionManager_DisconnectInactive(t *testing.T) {
 	lh := newTestLighthouse()
 	ifce := &Interface{
 		hostMap:          hostMap,
-		inside:           &device.NoopTun{},
+		inside:           &test.NoopTun{},
 		outside:          &udp.NoopConn{},
 		firewall:         &Firewall{},
 		lightHouse:       lh,
@@ -348,7 +347,7 @@ func Test_NewConnectionManagerTest_DisconnectInvalid(t *testing.T) {
 	lh := newTestLighthouse()
 	ifce := &Interface{
 		hostMap:          hostMap,
-		inside:           &device.NoopTun{},
+		inside:           &test.NoopTun{},
 		outside:          &udp.NoopConn{},
 		firewall:         &Firewall{},
 		lightHouse:       lh,

firewall.go

@@ -81,14 +81,8 @@ type FirewallConntrack struct {
 
 	Conns      map[firewall.Packet]*conn
 	TimerWheel *TimerWheel[firewall.Packet]
-
-	// purgeCounter tracks lookups to trigger periodic purge instead of every lookup
-	purgeCounter uint32
 }
 
-// purgeInterval defines how many lookups between purge attempts
-const conntrackPurgeInterval = 1024
-
 // FirewallTable is the entry point for a rule, the evaluation order is:
 // Proto AND port AND (CA SHA or CA name) AND local CIDR AND (group OR groups OR name OR remote CIDR)
 type FirewallTable struct {
@@ -498,17 +492,14 @@ func (f *Firewall) inConns(fp firewall.Packet, h *HostInfo, caPool *cert.CAPool,
 	conntrack := f.Conntrack
 	conntrack.Lock()
 
-	// Periodic purge instead of every lookup (major CPU savings)
-	conntrack.purgeCounter++
-	if conntrack.purgeCounter >= conntrackPurgeInterval {
-		conntrack.purgeCounter = 0
-		ep, has := conntrack.TimerWheel.Purge()
-		if has {
-			f.evict(ep)
-		}
+	// Purge every time we test
+	ep, has := conntrack.TimerWheel.Purge()
+	if has {
+		f.evict(ep)
 	}
 
 	c, ok := conntrack.Conns[fp]
+
 	if !ok {
 		conntrack.Unlock()
 		return false

firewall/packet.go

@@ -1,9 +1,15 @@
 package firewall
 
 import (
+	"encoding/binary"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/netip"
+
+	"github.com/google/gopacket/layers"
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
 )
 
 type m = map[string]any
@@ -17,6 +23,17 @@ const (
 
 	PortAny      = 0  // Special value for matching `port: any`
 	PortFragment = -1 // Special value for matching `port: fragment`
+
+	minFwPacketLen = 4
+)
+
+var (
+	ErrPacketTooShort          = errors.New("packet is too short")
+	ErrUnknownIPVersion        = errors.New("packet is an unknown ip version")
+	ErrIPv4InvalidHeaderLength = errors.New("invalid ipv4 header length")
+	ErrIPv4PacketTooShort      = errors.New("ipv4 packet is too short")
+	ErrIPv6PacketTooShort      = errors.New("ipv6 packet is too short")
+	ErrIPv6CouldNotFindPayload = errors.New("could not find payload in ipv6 packet")
 )
 
 type Packet struct {
@@ -60,3 +77,172 @@ func (fp Packet) MarshalJSON() ([]byte, error) {
 		"Fragment":   fp.Fragment,
 	})
 }
+
+func parseV6(data []byte, incoming bool, fp *Packet) error {
+	dataLen := len(data)
+	if dataLen < ipv6.HeaderLen {
+		return ErrIPv6PacketTooShort
+	}
+
+	if incoming {
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[8:24])
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[24:40])
+	} else {
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[8:24])
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[24:40])
+	}
+
+	protoAt := 6             // NextHeader is at 6 bytes into the ipv6 header
+	offset := ipv6.HeaderLen // Start at the end of the ipv6 header
+	next := 0
+	for {
+		if protoAt >= dataLen {
+			break
+		}
+		proto := layers.IPProtocol(data[protoAt])
+
+		switch proto {
+		case layers.IPProtocolICMPv6, layers.IPProtocolESP, layers.IPProtocolNoNextHeader:
+			fp.Protocol = uint8(proto)
+			fp.RemotePort = 0
+			fp.LocalPort = 0
+			fp.Fragment = false
+			return nil
+
+		case layers.IPProtocolTCP, layers.IPProtocolUDP:
+			if dataLen < offset+4 {
+				return ErrIPv6PacketTooShort
+			}
+
+			fp.Protocol = uint8(proto)
+			if incoming {
+				fp.RemotePort = binary.BigEndian.Uint16(data[offset : offset+2])
+				fp.LocalPort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
+			} else {
+				fp.LocalPort = binary.BigEndian.Uint16(data[offset : offset+2])
+				fp.RemotePort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
+			}
+
+			fp.Fragment = false
+			return nil
+
+		case layers.IPProtocolIPv6Fragment:
+			// Fragment header is 8 bytes, need at least offset+4 to read the offset field
+			if dataLen < offset+8 {
+				return ErrIPv6PacketTooShort
+			}
+
+			// Check if this is the first fragment
+			fragmentOffset := binary.BigEndian.Uint16(data[offset+2:offset+4]) &^ uint16(0x7) // Remove the reserved and M flag bits
+			if fragmentOffset != 0 {
+				// Non-first fragment, use what we have now and stop processing
+				fp.Protocol = data[offset]
+				fp.Fragment = true
+				fp.RemotePort = 0
+				fp.LocalPort = 0
+				return nil
+			}
+
+			// The next loop should be the transport layer since we are the first fragment
+			next = 8 // Fragment headers are always 8 bytes
+
+		case layers.IPProtocolAH:
+			// Auth headers, used by IPSec, have a different meaning for header length
+			if dataLen <= offset+1 {
+				break
+			}
+
+			next = int(data[offset+1]+2) << 2
+
+		default:
+			// Normal ipv6 header length processing
+			if dataLen <= offset+1 {
+				break
+			}
+
+			next = int(data[offset+1]+1) << 3
+		}
+
+		if next <= 0 {
+			// Safety check, each ipv6 header has to be at least 8 bytes
+			next = 8
+		}
+
+		protoAt = offset
+		offset = offset + next
+	}
+
+	return ErrIPv6CouldNotFindPayload
+}
+
+func parseV4(data []byte, incoming bool, fp *Packet) error {
+	// Do we at least have an ipv4 header worth of data?
+	if len(data) < ipv4.HeaderLen {
+		return ErrIPv4PacketTooShort
+	}
+
+	// Adjust our start position based on the advertised ip header length
+	ihl := int(data[0]&0x0f) << 2
+
+	// Well-formed ip header length?
+	if ihl < ipv4.HeaderLen {
+		return ErrIPv4InvalidHeaderLength
+	}
+
+	// Check if this is the second or further fragment of a fragmented packet.
+	flagsfrags := binary.BigEndian.Uint16(data[6:8])
+	fp.Fragment = (flagsfrags & 0x1FFF) != 0
+
+	// Firewall handles protocol checks
+	fp.Protocol = data[9]
+
+	// Accounting for a variable header length, do we have enough data for our src/dst tuples?
+	minLen := ihl
+	if !fp.Fragment && fp.Protocol != ProtoICMP {
+		minLen += minFwPacketLen
+	}
+	if len(data) < minLen {
+		return ErrIPv4InvalidHeaderLength
+	}
+
+	// Firewall packets are locally oriented
+	if incoming {
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[12:16])
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[16:20])
+		if fp.Fragment || fp.Protocol == ProtoICMP {
+			fp.RemotePort = 0
+			fp.LocalPort = 0
+		} else {
+			fp.RemotePort = binary.BigEndian.Uint16(data[ihl : ihl+2])
+			fp.LocalPort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4])
+		}
+	} else {
+		fp.LocalAddr, _ = netip.AddrFromSlice(data[12:16])
+		fp.RemoteAddr, _ = netip.AddrFromSlice(data[16:20])
+		if fp.Fragment || fp.Protocol == ProtoICMP {
+			fp.RemotePort = 0
+			fp.LocalPort = 0
+		} else {
+			fp.LocalPort = binary.BigEndian.Uint16(data[ihl : ihl+2])
+			fp.RemotePort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4])
+		}
+	}
+
+	return nil
+}
+
+// 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 *Packet) error {
+	if len(data) < 1 {
+		return ErrPacketTooShort
+	}
+
+	version := int((data[0] >> 4) & 0x0f)
+	switch version {
+	case ipv4.Version:
+		return parseV4(data, incoming, fp)
+	case ipv6.Version:
+		return parseV6(data, incoming, fp)
+	}
+	return ErrUnknownIPVersion
+}

go.mod

@@ -4,6 +4,7 @@ go 1.25
 
 require (
 	dario.cat/mergo v1.0.2
+	filippo.io/bigmod v0.1.0
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be
 	github.com/armon/go-radix v1.0.0
 	github.com/cyberdelia/go-metrics-graphite v0.0.0-20161219230853-39f87cc3b432
@@ -30,11 +31,11 @@ require (
 	golang.org/x/sys v0.40.0
 	golang.org/x/term v0.39.0
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2
-	golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb
+	golang.zx2c4.com/wireguard v0.0.0-20230325221338-052af4a8072b
 	golang.zx2c4.com/wireguard/windows v0.5.3
 	google.golang.org/protobuf v1.36.11
 	gopkg.in/yaml.v3 v3.0.1
-	gvisor.dev/gvisor v0.0.0-20250503011706-39ed1f5ac29c
+	gvisor.dev/gvisor v0.0.0-20240423190808-9d7a357edefe
 )
 
 require (
@@ -50,6 +51,6 @@ require (
 	github.com/vishvananda/netns v0.0.5 // indirect
 	go.yaml.in/yaml/v2 v2.4.2 // indirect
 	golang.org/x/mod v0.31.0 // indirect
-	golang.org/x/time v0.7.0 // indirect
+	golang.org/x/time v0.5.0 // indirect
 	golang.org/x/tools v0.40.0 // indirect
 )

go.sum

@@ -1,6 +1,8 @@
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 dario.cat/mergo v1.0.2 h1:85+piFYR1tMbRrLcDwR18y4UKJ3aH1Tbzi24VRW1TK8=
 dario.cat/mergo v1.0.2/go.mod h1:E/hbnu0NxMFBjpMIE34DRGLWqDy0g5FuKDhCb31ngxA=
+filippo.io/bigmod v0.1.0 h1:UNzDk7y9ADKST+axd9skUpBQeW7fG2KrTZyOE4uGQy8=
+filippo.io/bigmod v0.1.0/go.mod h1:OjOXDNlClLblvXdwgFFOQFJEocLhhtai8vGLy0JCZlI=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
@@ -216,8 +218,8 @@ golang.org/x/term v0.39.0/go.mod h1:yxzUCTP/U+FzoxfdKmLaA0RV1WgE0VY7hXBwKtY/4ww=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/time v0.7.0 h1:ntUhktv3OPE6TgYxXWv9vKvUSJyIFJlyohwbkEwPrKQ=
-golang.org/x/time v0.7.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
+golang.org/x/time v0.5.0 h1:o7cqy6amK/52YcAKIPlM3a+Fpj35zvRj2TP+e1xFSfk=
+golang.org/x/time v0.5.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
@@ -231,8 +233,8 @@ golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8T
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 h1:B82qJJgjvYKsXS9jeunTOisW56dUokqW/FOteYJJ/yg=
 golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2/go.mod h1:deeaetjYA+DHMHg+sMSMI58GrEteJUUzzw7en6TJQcI=
-golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb h1:whnFRlWMcXI9d+ZbWg+4sHnLp52d5yiIPUxMBSt4X9A=
-golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb/go.mod h1:rpwXGsirqLqN2L0JDJQlwOboGHmptD5ZD6T2VmcqhTw=
+golang.zx2c4.com/wireguard v0.0.0-20230325221338-052af4a8072b h1:J1CaxgLerRR5lgx3wnr6L04cJFbWoceSK9JWBdglINo=
+golang.zx2c4.com/wireguard v0.0.0-20230325221338-052af4a8072b/go.mod h1:tqur9LnfstdR9ep2LaJT4lFUl0EjlHtge+gAjmsHUG4=
 golang.zx2c4.com/wireguard/windows v0.5.3 h1:On6j2Rpn3OEMXqBq00QEDC7bWSZrPIHKIus8eIuExIE=
 golang.zx2c4.com/wireguard/windows v0.5.3/go.mod h1:9TEe8TJmtwyQebdFwAkEWOPr3prrtqm+REGFifP60hI=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
@@ -258,5 +260,5 @@ gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gvisor.dev/gvisor v0.0.0-20250503011706-39ed1f5ac29c h1:m/r7OM+Y2Ty1sgBQ7Qb27VgIMBW8ZZhT4gLnUyDIhzI=
-gvisor.dev/gvisor v0.0.0-20250503011706-39ed1f5ac29c/go.mod h1:3r5CMtNQMKIvBlrmM9xWUNamjKBYPOWyXOjmg5Kts3g=
+gvisor.dev/gvisor v0.0.0-20240423190808-9d7a357edefe h1:fre4i6mv4iBuz5lCMOzHD1rH1ljqHWSICFmZRbbgp3g=
+gvisor.dev/gvisor v0.0.0-20240423190808-9d7a357edefe/go.mod h1:sxc3Uvk/vHcd3tj7/DHVBoR5wvWT/MmRq2pj7HRJnwU=

inside.go

@@ -2,8 +2,6 @@ package nebula
 
 import (
 	"net/netip"
-	"sync"
-	"time"
 
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/firewall"
@@ -13,260 +11,8 @@ import (
 	"github.com/slackhq/nebula/routing"
 )
 
-// preEncryptionPacket holds packet data before batch encryption
-type preEncryptionPacket struct {
-	hostinfo *HostInfo
-	ci       *ConnectionState
-	packet   []byte
-	out      []byte
-}
-
-// Pool for preEncryptionBatch slices to reduce allocations
-var preEncryptionBatchPool = sync.Pool{
-	New: func() any {
-		// Pre-allocate with reasonable capacity
-		batch := make([]preEncryptionPacket, 0, 128)
-		return &batch
-	},
-}
-
-// consumeInsidePackets processes multiple packets in a batch for improved performance
-// packets: slice of packet buffers to process
-// sizes: slice of packet sizes
-// count: number of packets to process
-// outs: slice of output buffers (one per packet) with virtio headroom
-// q: queue index
-// localCache: firewall conntrack cache
-// batchPackets: pre-allocated slice for accumulating encrypted packets
-// batchAddrs: pre-allocated slice for accumulating destination addresses
-func (f *Interface) consumeInsidePackets(packets [][]byte, sizes []int, count int, outs [][]byte, nb []byte, q int, localCache firewall.ConntrackCache, batchPackets *[][]byte, batchAddrs *[]netip.AddrPort) {
-	// Reusable per-packet state
-	fwPacket := &firewall.Packet{}
-
-	// Reset batch accumulation slices (reuse capacity)
-	*batchPackets = (*batchPackets)[:0]
-	*batchAddrs = (*batchAddrs)[:0]
-
-	// Collect packets for batched encryption
-	preEncryptionBatch := make([]preEncryptionPacket, 0, count)
-
-	// Process each packet in the batch
-	for i := 0; i < count; i++ {
-		packet := packets[i][:sizes[i]]
-		out := outs[i]
-
-		// Inline the consumeInsidePacket logic for better performance
-		err := newPacket(packet, false, fwPacket)
-		if err != nil {
-			if f.l.Level >= logrus.DebugLevel {
-				f.l.WithField("packet", packet).Debugf("Error while validating outbound packet: %s", err)
-			}
-			continue
-		}
-
-		// Ignore local broadcast packets
-		if f.dropLocalBroadcast {
-			if f.myBroadcastAddrsTable.Contains(fwPacket.RemoteAddr) {
-				continue
-			}
-		}
-
-		if f.myVpnAddrsTable.Contains(fwPacket.RemoteAddr) {
-			// Immediately forward packets from self to self.
-			if immediatelyForwardToSelf {
-				_, err := f.readers[q].Write(packet)
-				if err != nil {
-					f.l.WithError(err).Error("Failed to forward to tun")
-				}
-			}
-			continue
-		}
-
-		// Ignore multicast packets
-		if f.dropMulticast && fwPacket.RemoteAddr.IsMulticast() {
-			continue
-		}
-
-		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, out, q)
-			if f.l.Level >= logrus.DebugLevel {
-				f.l.WithField("vpnAddr", fwPacket.RemoteAddr).
-					WithField("fwPacket", fwPacket).
-					Debugln("dropping outbound packet, vpnAddr not in our vpn networks or in unsafe networks")
-			}
-			continue
-		}
-
-		if !ready {
-			continue
-		}
-
-		dropReason := f.firewall.Drop(*fwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
-		if dropReason != nil {
-			f.rejectInside(packet, out, q)
-			if f.l.Level >= logrus.DebugLevel {
-				hostinfo.logger(f.l).
-					WithField("fwPacket", fwPacket).
-					WithField("reason", dropReason).
-					Debugln("dropping outbound packet")
-			}
-			continue
-		}
-
-		// Prepare packet for batch encryption
-		ci := hostinfo.ConnectionState
-		if ci.eKey == nil {
-			continue
-		}
-
-		// Check if this needs relay - if so, send immediately and skip batching
-		useRelay := !hostinfo.remote.IsValid()
-		if useRelay {
-			// Handle relay sends individually (less common path)
-			f.sendNoMetrics(header.Message, 0, ci, hostinfo, netip.AddrPort{}, packet, nb, out, q)
-			continue
-		}
-
-		// Collect for batched encryption
-		preEncryptionBatch = append(preEncryptionBatch, preEncryptionPacket{
-			hostinfo: hostinfo,
-			ci:       ci,
-			packet:   packet,
-			out:      out,
-		})
-	}
-
-	// BATCH ENCRYPTION: Process all collected packets
-	if len(preEncryptionBatch) > 0 {
-		f.encryptBatch(preEncryptionBatch, nb, batchPackets, batchAddrs)
-	}
-
-	// Send all accumulated packets in one batch
-	if len(*batchPackets) > 0 {
-		batchSize := len(*batchPackets)
-		n, err := f.writers[q].WriteMulti(*batchPackets, *batchAddrs)
-		if err != nil {
-			f.l.WithError(err).WithField("sent", n).WithField("total", batchSize).Error("Failed to send batch")
-		}
-	}
-}
-
-// encryptBatch processes multiple packets, grouping by ConnectionState to reduce lock acquisitions
-func (f *Interface) encryptBatch(batch []preEncryptionPacket, nb []byte, batchPackets *[][]byte, batchAddrs *[]netip.AddrPort) {
-	lockStart := time.Now()
-	lockAcquisitions := int64(0)
-
-	if noiseutil.EncryptLockNeeded {
-		// Group packets by ConnectionState to minimize lock acquisitions
-		// Process packets in order but batch lock acquisitions per CI
-		var currentCI *ConnectionState
-		var lockHeld bool
-
-		for i := range batch {
-			ci := batch[i].ci
-			hostinfo := batch[i].hostinfo
-
-			// Validate packet data to prevent nil pointer dereference
-			if ci == nil || hostinfo == nil {
-				continue
-			}
-
-			// Switch locks if we're moving to a different ConnectionState
-			if ci != currentCI {
-				if lockHeld {
-					currentCI.writeLock.Unlock()
-				}
-				ci.writeLock.Lock()
-				lockAcquisitions++
-				currentCI = ci
-				lockHeld = true
-			}
-
-			c := ci.messageCounter.Add(1)
-			out := header.Encode(batch[i].out, header.Version, header.Message, 0, hostinfo.remoteIndexId, c)
-			f.connectionManager.Out(hostinfo)
-
-			// Query lighthouse if needed
-			if hostinfo.lastRebindCount != f.rebindCount {
-				f.lightHouse.QueryServer(hostinfo.vpnAddrs[0])
-				hostinfo.lastRebindCount = f.rebindCount
-				if f.l.Level >= logrus.DebugLevel {
-					f.l.WithField("vpnAddrs", hostinfo.vpnAddrs).Debug("Lighthouse update triggered for punch due to rebind counter")
-				}
-			}
-
-			var err error
-			out, err = ci.eKey.EncryptDanger(out, out, batch[i].packet, c, nb)
-			if err != nil {
-				hostinfo.logger(f.l).WithError(err).
-					WithField("counter", c).
-					Error("Failed to encrypt outgoing packet")
-				continue
-			}
-
-			// Add to output batches
-			*batchPackets = append(*batchPackets, out)
-			*batchAddrs = append(*batchAddrs, hostinfo.remote)
-		}
-
-		// Release final lock
-		if lockHeld {
-			currentCI.writeLock.Unlock()
-		}
-	} else {
-		// No locks needed - process directly
-		for i := range batch {
-			ci := batch[i].ci
-			hostinfo := batch[i].hostinfo
-
-			// Validate packet data to prevent nil pointer dereference
-			if ci == nil || hostinfo == nil {
-				continue
-			}
-
-			c := ci.messageCounter.Add(1)
-			out := header.Encode(batch[i].out, header.Version, header.Message, 0, hostinfo.remoteIndexId, c)
-			f.connectionManager.Out(hostinfo)
-
-			// Query lighthouse if needed
-			if hostinfo.lastRebindCount != f.rebindCount {
-				f.lightHouse.QueryServer(hostinfo.vpnAddrs[0])
-				hostinfo.lastRebindCount = f.rebindCount
-				if f.l.Level >= logrus.DebugLevel {
-					f.l.WithField("vpnAddrs", hostinfo.vpnAddrs).Debug("Lighthouse update triggered for punch due to rebind counter")
-				}
-			}
-
-			var err error
-			out, err = ci.eKey.EncryptDanger(out, out, batch[i].packet, c, nb)
-			if err != nil {
-				hostinfo.logger(f.l).WithError(err).
-					WithField("counter", c).
-					Error("Failed to encrypt outgoing packet")
-				continue
-			}
-
-			// Add to output batches
-			*batchPackets = append(*batchPackets, out)
-			*batchAddrs = append(*batchAddrs, hostinfo.remote)
-		}
-	}
-
-	// Record metrics
-	encryptionTime := time.Since(lockStart)
-	if noiseutil.EncryptLockNeeded {
-		f.batchMetrics.lockAcquisitions.Inc(lockAcquisitions)
-	}
-	f.batchMetrics.encryptionTime.Update(encryptionTime.Nanoseconds())
-	f.batchMetrics.batchSize.Update(int64(len(batch)))
-}
-
 func (f *Interface) consumeInsidePacket(packet []byte, fwPacket *firewall.Packet, nb, out []byte, q int, localCache firewall.ConntrackCache) {
-	err := newPacket(packet, false, fwPacket)
+	err := firewall.NewPacket(packet, false, fwPacket)
 	if err != nil {
 		if f.l.Level >= logrus.DebugLevel {
 			f.l.WithField("packet", packet).Debugf("Error while validating outbound packet: %s", err)
@@ -465,7 +211,7 @@ 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.Packet{}
-	err := newPacket(p, false, fp)
+	err := firewall.NewPacket(p, false, fp)
 	if err != nil {
 		f.l.Warnf("error while parsing outgoing packet for firewall check; %v", err)
 		return

interface.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"net/netip"
 	"os"
 	"runtime"
@@ -21,7 +22,6 @@ import (
 )
 
 const mtu = 9001
-const virtioNetHdrLen = overlay.VirtioNetHdrLen
 
 type InterfaceConfig struct {
 	HostMap            *HostMap
@@ -50,13 +50,6 @@ type InterfaceConfig struct {
 	l                     *logrus.Logger
 }
 
-type batchMetrics struct {
-	udpReadSize      metrics.Histogram
-	encryptionTime   metrics.Histogram // Time spent in encryption (including lock waits)
-	batchSize        metrics.Histogram // Dynamic batch sizes being used
-	lockAcquisitions metrics.Counter   // Number of lock acquisitions (should be minimal)
-}
-
 type Interface struct {
 	hostMap               *HostMap
 	outside               udp.Conn
@@ -94,12 +87,11 @@ type Interface struct {
 	conntrackCacheTimeout time.Duration
 
 	writers []udp.Conn
-	readers []overlay.BatchReadWriter
+	readers []io.ReadWriteCloser
 
 	metricHandshakes    metrics.Histogram
 	messageMetrics      *MessageMetrics
 	cachedPacketMetrics *cachedPacketMetrics
-	batchMetrics        *batchMetrics
 
 	l *logrus.Logger
 }
@@ -186,7 +178,7 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		routines:              c.routines,
 		version:               c.version,
 		writers:               make([]udp.Conn, c.routines),
-		readers:               make([]overlay.BatchReadWriter, c.routines),
+		readers:               make([]io.ReadWriteCloser, c.routines),
 		myVpnNetworks:         cs.myVpnNetworks,
 		myVpnNetworksTable:    cs.myVpnNetworksTable,
 		myVpnAddrs:            cs.myVpnAddrs,
@@ -202,12 +194,6 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 			sent:    metrics.GetOrRegisterCounter("hostinfo.cached_packets.sent", nil),
 			dropped: metrics.GetOrRegisterCounter("hostinfo.cached_packets.dropped", nil),
 		},
-		batchMetrics: &batchMetrics{
-			udpReadSize:      metrics.GetOrRegisterHistogram("batch.udp_read_size", nil, metrics.NewUniformSample(1024)),
-			encryptionTime:   metrics.GetOrRegisterHistogram("batch.encryption_time_ns", nil, metrics.NewUniformSample(1024)),
-			batchSize:        metrics.GetOrRegisterHistogram("batch.size", nil, metrics.NewUniformSample(1024)),
-			lockAcquisitions: metrics.GetOrRegisterCounter("batch.lock_acquisitions", nil),
-		},
 
 		l: c.l,
 	}
@@ -247,7 +233,7 @@ func (f *Interface) activate() {
 	metrics.GetOrRegisterGauge("routines", nil).Update(int64(f.routines))
 
 	// Prepare n tun queues
-	var reader overlay.BatchReadWriter = f.inside
+	var reader io.ReadWriteCloser = f.inside
 	for i := 0; i < f.routines; i++ {
 		if i > 0 {
 			reader, err = f.inside.NewMultiQueueReader()
@@ -288,68 +274,39 @@ func (f *Interface) listenOut(i int) {
 
 	ctCache := firewall.NewConntrackCacheTicker(f.conntrackCacheTimeout)
 	lhh := f.lightHouse.NewRequestHandler()
-
-	// Pre-allocate output buffers for batch processing
-	batchSize := li.BatchSize()
-	outs := make([][]byte, batchSize)
-	for idx := range outs {
-		// Allocate full buffer with virtio header space
-		outs[idx] = make([]byte, virtioNetHdrLen, virtioNetHdrLen+udp.MTU)
-	}
-
+	plaintext := make([]byte, udp.MTU)
 	h := &header.H{}
 	fwPacket := &firewall.Packet{}
-	nb := make([]byte, 12)
-
-	li.ListenOutBatch(func(addrs []netip.AddrPort, payloads [][]byte, count int) {
-		f.readOutsidePacketsBatch(addrs, payloads, count, outs[:count], nb, i, h, fwPacket, lhh, ctCache.Get(f.l))
+	nb := make([]byte, 12, 12)
 
+	li.ListenOut(func(fromUdpAddr netip.AddrPort, payload []byte) {
+		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, plaintext[:0], payload, h, fwPacket, lhh, nb, i, ctCache.Get(f.l))
 	})
 }
 
-func (f *Interface) listenIn(reader overlay.BatchReadWriter, i int) {
+func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
 	runtime.LockOSThread()
 
-	batchSize := reader.BatchSize()
-
-	// Allocate buffers for batch reading
-	bufs := make([][]byte, batchSize)
-	for idx := range bufs {
-		bufs[idx] = make([]byte, mtu)
-	}
-	sizes := make([]int, batchSize)
-
-	// Allocate output buffers for batch processing (one per packet)
-	// Each has virtio header headroom to avoid copies on write
-	outs := make([][]byte, batchSize)
-	for idx := range outs {
-		outBuf := make([]byte, virtioNetHdrLen+mtu)
-		outs[idx] = outBuf[virtioNetHdrLen:] // Slice starting after headroom
-	}
-
-	// Pre-allocate batch accumulation buffers for sending
-	batchPackets := make([][]byte, 0, batchSize)
-	batchAddrs := make([]netip.AddrPort, 0, batchSize)
-
-	// Pre-allocate nonce buffer (reused for all encryptions)
-	nb := make([]byte, 12)
+	packet := make([]byte, mtu)
+	out := make([]byte, mtu)
+	fwPacket := &firewall.Packet{}
+	nb := make([]byte, 12, 12)
 
 	conntrackCache := firewall.NewConntrackCacheTicker(f.conntrackCacheTimeout)
 
 	for {
-		n, err := reader.BatchRead(bufs, sizes)
+		n, err := reader.Read(packet)
 		if err != nil {
 			if errors.Is(err, os.ErrClosed) && f.closed.Load() {
 				return
 			}
 
-			f.l.WithError(err).Error("Error while batch reading outbound packets")
+			f.l.WithError(err).Error("Error while reading outbound packet")
 			// This only seems to happen when something fatal happens to the fd, so exit.
 			os.Exit(2)
 		}
 
-		// Process all packets in the batch at once
-		f.consumeInsidePackets(bufs, sizes, n, outs, nb, i, conntrackCache.Get(f.l), &batchPackets, &batchAddrs)
+		f.consumeInsidePacket(packet[:n], fwPacket, nb, out, i, conntrackCache.Get(f.l))
 	}
 }
 

main.go

@@ -171,7 +171,7 @@ func Main(c *config.C, configTest bool, buildVersion string, logger *logrus.Logg
 
 		for i := 0; i < routines; i++ {
 			l.Infof("listening on %v", netip.AddrPortFrom(listenHost, uint16(port)))
-			udpServer, err := udp.NewListener(l, listenHost, port, routines > 1, c.GetInt("listen.batch", 128))
+			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)
 			}

outside.go

@@ -1,22 +1,13 @@
 package nebula
 
 import (
-	"encoding/binary"
 	"errors"
 	"net/netip"
 	"time"
 
-	"github.com/google/gopacket/layers"
-	"golang.org/x/net/ipv6"
-
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/header"
-	"golang.org/x/net/ipv4"
-)
-
-const (
-	minFwPacketLen = 4
 )
 
 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) {
@@ -102,7 +93,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 					relay:     relay,
 					IsRelayed: true,
 				}
-				f.readOutsidePackets(via, out[:virtioNetHdrLen], signedPayload, h, fwPacket, lhf, nb, q, localCache)
+				f.readOutsidePackets(via, out[:0], signedPayload, h, fwPacket, lhf, nb, q, localCache)
 				return
 			case ForwardingType:
 				// Find the target HostInfo relay object
@@ -145,7 +136,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 		}
 
 		//TODO: assert via is not relayed
-		lhf.HandleRequest(via.UdpAddr, hostinfo.vpnAddrs, d[virtioNetHdrLen:], f)
+		lhf.HandleRequest(via.UdpAddr, hostinfo.vpnAddrs, d, f)
 
 		// Fallthrough to the bottom to record incoming traffic
 
@@ -167,7 +158,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 			// This testRequest might be from TryPromoteBest, so we should roam
 			// to the new IP address before responding
 			f.handleHostRoaming(hostinfo, via)
-			f.send(header.Test, header.TestReply, ci, hostinfo, d[virtioNetHdrLen:], nb, out)
+			f.send(header.Test, header.TestReply, ci, hostinfo, d, nb, out)
 		}
 
 		// Fallthrough to the bottom to record incoming traffic
@@ -210,7 +201,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 			return
 		}
 
-		f.relayManager.HandleControlMsg(hostinfo, d[virtioNetHdrLen:], f)
+		f.relayManager.HandleControlMsg(hostinfo, d, f)
 
 	default:
 		f.messageMetrics.Rx(h.Type, h.Subtype, 1)
@@ -278,184 +269,6 @@ func (f *Interface) handleEncrypted(ci *ConnectionState, via ViaSender, h *heade
 	return true
 }
 
-var (
-	ErrPacketTooShort          = errors.New("packet is too short")
-	ErrUnknownIPVersion        = errors.New("packet is an unknown ip version")
-	ErrIPv4InvalidHeaderLength = errors.New("invalid ipv4 header length")
-	ErrIPv4PacketTooShort      = errors.New("ipv4 packet is too short")
-	ErrIPv6PacketTooShort      = errors.New("ipv6 packet is too short")
-	ErrIPv6CouldNotFindPayload = errors.New("could not find payload in ipv6 packet")
-)
-
-// 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.Packet) error {
-	if len(data) < 1 {
-		return ErrPacketTooShort
-	}
-
-	version := int((data[0] >> 4) & 0x0f)
-	switch version {
-	case ipv4.Version:
-		return parseV4(data, incoming, fp)
-	case ipv6.Version:
-		return parseV6(data, incoming, fp)
-	}
-	return ErrUnknownIPVersion
-}
-
-func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
-	dataLen := len(data)
-	if dataLen < ipv6.HeaderLen {
-		return ErrIPv6PacketTooShort
-	}
-
-	if incoming {
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[8:24])
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[24:40])
-	} else {
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[8:24])
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[24:40])
-	}
-
-	protoAt := 6             // NextHeader is at 6 bytes into the ipv6 header
-	offset := ipv6.HeaderLen // Start at the end of the ipv6 header
-	next := 0
-	for {
-		if protoAt >= dataLen {
-			break
-		}
-		proto := layers.IPProtocol(data[protoAt])
-
-		switch proto {
-		case layers.IPProtocolICMPv6, layers.IPProtocolESP, layers.IPProtocolNoNextHeader:
-			fp.Protocol = uint8(proto)
-			fp.RemotePort = 0
-			fp.LocalPort = 0
-			fp.Fragment = false
-			return nil
-
-		case layers.IPProtocolTCP, layers.IPProtocolUDP:
-			if dataLen < offset+4 {
-				return ErrIPv6PacketTooShort
-			}
-
-			fp.Protocol = uint8(proto)
-			if incoming {
-				fp.RemotePort = binary.BigEndian.Uint16(data[offset : offset+2])
-				fp.LocalPort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
-			} else {
-				fp.LocalPort = binary.BigEndian.Uint16(data[offset : offset+2])
-				fp.RemotePort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
-			}
-
-			fp.Fragment = false
-			return nil
-
-		case layers.IPProtocolIPv6Fragment:
-			// Fragment header is 8 bytes, need at least offset+4 to read the offset field
-			if dataLen < offset+8 {
-				return ErrIPv6PacketTooShort
-			}
-
-			// Check if this is the first fragment
-			fragmentOffset := binary.BigEndian.Uint16(data[offset+2:offset+4]) &^ uint16(0x7) // Remove the reserved and M flag bits
-			if fragmentOffset != 0 {
-				// Non-first fragment, use what we have now and stop processing
-				fp.Protocol = data[offset]
-				fp.Fragment = true
-				fp.RemotePort = 0
-				fp.LocalPort = 0
-				return nil
-			}
-
-			// The next loop should be the transport layer since we are the first fragment
-			next = 8 // Fragment headers are always 8 bytes
-
-		case layers.IPProtocolAH:
-			// Auth headers, used by IPSec, have a different meaning for header length
-			if dataLen <= offset+1 {
-				break
-			}
-
-			next = int(data[offset+1]+2) << 2
-
-		default:
-			// Normal ipv6 header length processing
-			if dataLen <= offset+1 {
-				break
-			}
-
-			next = int(data[offset+1]+1) << 3
-		}
-
-		if next <= 0 {
-			// Safety check, each ipv6 header has to be at least 8 bytes
-			next = 8
-		}
-
-		protoAt = offset
-		offset = offset + next
-	}
-
-	return ErrIPv6CouldNotFindPayload
-}
-
-func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
-	// Do we at least have an ipv4 header worth of data?
-	if len(data) < ipv4.HeaderLen {
-		return ErrIPv4PacketTooShort
-	}
-
-	// Adjust our start position based on the advertised ip header length
-	ihl := int(data[0]&0x0f) << 2
-
-	// Well-formed ip header length?
-	if ihl < ipv4.HeaderLen {
-		return ErrIPv4InvalidHeaderLength
-	}
-
-	// Check if this is the second or further fragment of a fragmented packet.
-	flagsfrags := binary.BigEndian.Uint16(data[6:8])
-	fp.Fragment = (flagsfrags & 0x1FFF) != 0
-
-	// Firewall handles protocol checks
-	fp.Protocol = data[9]
-
-	// Accounting for a variable header length, do we have enough data for our src/dst tuples?
-	minLen := ihl
-	if !fp.Fragment && fp.Protocol != firewall.ProtoICMP {
-		minLen += minFwPacketLen
-	}
-	if len(data) < minLen {
-		return ErrIPv4InvalidHeaderLength
-	}
-
-	// Firewall packets are locally oriented
-	if incoming {
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[12:16])
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[16:20])
-		if fp.Fragment || fp.Protocol == firewall.ProtoICMP {
-			fp.RemotePort = 0
-			fp.LocalPort = 0
-		} else {
-			fp.RemotePort = binary.BigEndian.Uint16(data[ihl : ihl+2])
-			fp.LocalPort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4])
-		}
-	} else {
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[12:16])
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[16:20])
-		if fp.Fragment || fp.Protocol == firewall.ProtoICMP {
-			fp.RemotePort = 0
-			fp.LocalPort = 0
-		} else {
-			fp.LocalPort = binary.BigEndian.Uint16(data[ihl : ihl+2])
-			fp.RemotePort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4])
-		}
-	}
-
-	return nil
-}
-
 func (f *Interface) decrypt(hostinfo *HostInfo, mc uint64, out []byte, packet []byte, h *header.H, nb []byte) ([]byte, error) {
 	var err error
 	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], mc, nb)
@@ -481,11 +294,9 @@ func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out
 		return false
 	}
 
-	packetData := out[virtioNetHdrLen:]
-
-	err = newPacket(packetData, true, fwPacket)
+	err = firewall.NewPacket(out, true, fwPacket)
 	if err != nil {
-		hostinfo.logger(f.l).WithError(err).WithField("packet", packetData).
+		hostinfo.logger(f.l).WithError(err).WithField("packet", out).
 			Warnf("Error while validating inbound packet")
 		return false
 	}
@@ -500,7 +311,7 @@ func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out
 	if dropReason != nil {
 		// NOTE: We give `packet` as the `out` here since we already decrypted from it and we don't need it anymore
 		// This gives us a buffer to build the reject packet in
-		f.rejectOutside(packetData, hostinfo.ConnectionState, hostinfo, nb, packet, q)
+		f.rejectOutside(out, hostinfo.ConnectionState, hostinfo, nb, packet, q)
 		if f.l.Level >= logrus.DebugLevel {
 			hostinfo.logger(f.l).WithField("fwPacket", fwPacket).
 				WithField("reason", dropReason).
@@ -564,108 +375,3 @@ func (f *Interface) handleRecvError(addr netip.AddrPort, h *header.H) {
 	// We also delete it from pending hostmap to allow for fast reconnect.
 	f.handshakeManager.DeleteHostInfo(hostinfo)
 }
-
-// readOutsidePacketsBatch processes multiple packets received from UDP in a batch
-// and writes all successfully decrypted packets to TUN in a single operation
-func (f *Interface) readOutsidePacketsBatch(addrs []netip.AddrPort, payloads [][]byte, count int, outs [][]byte, nb []byte, q int, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, localCache firewall.ConntrackCache) {
-	// Pre-allocate slice for accumulating successful decryptions
-	tunPackets := make([][]byte, 0, count)
-
-	for i := 0; i < count; i++ {
-		payload := payloads[i]
-		addr := addrs[i]
-		out := outs[i]
-
-		// Parse header
-		err := h.Parse(payload)
-		if err != nil {
-			if len(payload) > 1 {
-				f.l.WithField("packet", payload).Infof("Error while parsing inbound packet from %s: %s", addr, err)
-			}
-			continue
-		}
-
-		if addr.IsValid() {
-			if f.myVpnNetworksTable.Contains(addr.Addr()) {
-				if f.l.Level >= logrus.DebugLevel {
-					f.l.WithField("udpAddr", addr).Debug("Refusing to process double encrypted packet")
-				}
-				continue
-			}
-		}
-
-		var hostinfo *HostInfo
-		if h.Type == header.Message && h.Subtype == header.MessageRelay {
-			hostinfo = f.hostMap.QueryRelayIndex(h.RemoteIndex)
-		} else {
-			hostinfo = f.hostMap.QueryIndex(h.RemoteIndex)
-		}
-
-		var ci *ConnectionState
-		if hostinfo != nil {
-			ci = hostinfo.ConnectionState
-		}
-
-		switch h.Type {
-		case header.Message:
-			if !f.handleEncrypted(ci, ViaSender{UdpAddr: addr}, h) {
-				continue
-			}
-
-			switch h.Subtype {
-			case header.MessageNone:
-				// Decrypt packet
-				out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, payload[:header.Len], payload[header.Len:], h.MessageCounter, nb)
-				if err != nil {
-					hostinfo.logger(f.l).WithError(err).Error("Failed to decrypt packet")
-					continue
-				}
-
-				packetData := out[virtioNetHdrLen:]
-
-				err = newPacket(packetData, true, fwPacket)
-				if err != nil {
-					hostinfo.logger(f.l).WithError(err).WithField("packet", packetData).Warnf("Error while validating inbound packet")
-					continue
-				}
-
-				if !hostinfo.ConnectionState.window.Update(f.l, h.MessageCounter) {
-					hostinfo.logger(f.l).WithField("fwPacket", fwPacket).Debugln("dropping out of window packet")
-					continue
-				}
-
-				dropReason := f.firewall.Drop(*fwPacket, true, hostinfo, f.pki.GetCAPool(), localCache)
-				if dropReason != nil {
-					f.rejectOutside(packetData, hostinfo.ConnectionState, hostinfo, nb, payload, q)
-					if f.l.Level >= logrus.DebugLevel {
-						hostinfo.logger(f.l).WithField("fwPacket", fwPacket).WithField("reason", dropReason).Debugln("dropping inbound packet")
-					}
-					continue
-				}
-
-				f.connectionManager.In(hostinfo)
-				// Add to batch for TUN write
-				tunPackets = append(tunPackets, out)
-
-			case header.MessageRelay:
-				// Skip relay packets in batch mode for now (less common path)
-				f.readOutsidePackets(ViaSender{UdpAddr: addr}, out[:virtioNetHdrLen], payload, h, fwPacket, lhf, nb, q, localCache)
-
-			default:
-				hostinfo.logger(f.l).Debugf("unexpected message subtype %d", h.Subtype)
-			}
-
-		default:
-			// Handle non-Message types using single-packet path
-			f.readOutsidePackets(ViaSender{UdpAddr: addr}, out[:virtioNetHdrLen], payload, h, fwPacket, lhf, nb, q, localCache)
-		}
-	}
-
-	if len(tunPackets) > 0 {
-		n, err := f.readers[q].WriteBatch(tunPackets, virtioNetHdrLen)
-		if err != nil {
-			f.l.WithError(err).WithField("sent", n).WithField("total", len(tunPackets)).Error("Failed to batch write to tun")
-		}
-
-	}
-}

outside_test.go

@@ -20,13 +20,13 @@ func Test_newPacket(t *testing.T) {
 	p := &firewall.Packet{}
 
 	// length fails
-	err := newPacket([]byte{}, true, p)
+	err := firewall.NewPacket([]byte{}, true, p)
 	require.ErrorIs(t, err, ErrPacketTooShort)
 
-	err = newPacket([]byte{0x40}, true, p)
+	err = firewall.NewPacket([]byte{0x40}, true, p)
 	require.ErrorIs(t, err, ErrIPv4PacketTooShort)
 
-	err = newPacket([]byte{0x60}, true, p)
+	err = firewall.NewPacket([]byte{0x60}, true, p)
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// length fail with ip options
@@ -39,15 +39,15 @@ func Test_newPacket(t *testing.T) {
 	}
 
 	b, _ := h.Marshal()
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.ErrorIs(t, err, ErrIPv4InvalidHeaderLength)
 
 	// not an ipv4 packet
-	err = newPacket([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
+	err = firewall.NewPacket([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
 	require.ErrorIs(t, err, ErrUnknownIPVersion)
 
 	// invalid ihl
-	err = newPacket([]byte{4<<4 | (8 >> 2 & 0x0f), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
+	err = firewall.NewPacket([]byte{4<<4 | (8 >> 2 & 0x0f), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
 	require.ErrorIs(t, err, ErrIPv4InvalidHeaderLength)
 
 	// account for variable ip header length - incoming
@@ -62,7 +62,7 @@ func Test_newPacket(t *testing.T) {
 
 	b, _ = h.Marshal()
 	b = append(b, []byte{0, 3, 0, 4}...)
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
@@ -84,7 +84,7 @@ func Test_newPacket(t *testing.T) {
 
 	b, _ = h.Marshal()
 	b = append(b, []byte{0, 5, 0, 6}...)
-	err = newPacket(b, false, p)
+	err = firewall.NewPacket(b, false, p)
 
 	require.NoError(t, err)
 	assert.Equal(t, uint8(2), p.Protocol)
@@ -114,7 +114,7 @@ func Test_newPacket_v6(t *testing.T) {
 	err := gopacket.SerializeLayers(buffer, opt, &ip)
 	require.NoError(t, err)
 
-	err = newPacket(buffer.Bytes(), true, p)
+	err = firewall.NewPacket(buffer.Bytes(), true, p)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A v6 packet with a hop-by-hop extension
@@ -148,12 +148,12 @@ func Test_newPacket_v6(t *testing.T) {
 
 	// A full IPv6 header and 1 byte in the first extension, but missing
 	// the length byte.
-	err = newPacket(buffer.Bytes()[:41], true, p)
+	err = firewall.NewPacket(buffer.Bytes()[:41], true, p)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A full IPv6 header plus 1 full extension, but only 1 byte of the
 	// next layer, missing length byte
-	err = newPacket(buffer.Bytes()[:49], true, p)
+	err = firewall.NewPacket(buffer.Bytes()[:49], true, p)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A good ICMP packet
@@ -173,7 +173,7 @@ func Test_newPacket_v6(t *testing.T) {
 		panic(err)
 	}
 
-	err = newPacket(buffer.Bytes(), true, p)
+	err = firewall.NewPacket(buffer.Bytes(), true, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(layers.IPProtocolICMPv6), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -185,7 +185,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// A good ESP packet
 	b := buffer.Bytes()
 	b[6] = byte(layers.IPProtocolESP)
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(layers.IPProtocolESP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -197,7 +197,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// A good None packet
 	b = buffer.Bytes()
 	b[6] = byte(layers.IPProtocolNoNextHeader)
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(layers.IPProtocolNoNextHeader), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -209,7 +209,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// An unknown protocol packet
 	b = buffer.Bytes()
 	b[6] = 255 // 255 is a reserved protocol number
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A good UDP packet
@@ -236,7 +236,7 @@ func Test_newPacket_v6(t *testing.T) {
 	b = buffer.Bytes()
 
 	// incoming
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -246,7 +246,7 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// outgoing
-	err = newPacket(b, false, p)
+	err = firewall.NewPacket(b, false, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
@@ -256,14 +256,14 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Too short UDP packet
-	err = newPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
+	err = firewall.NewPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// A good TCP packet
 	b[6] = byte(layers.IPProtocolTCP)
 
 	// incoming
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -273,7 +273,7 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// outgoing
-	err = newPacket(b, false, p)
+	err = firewall.NewPacket(b, false, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
@@ -283,7 +283,7 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Too short TCP packet
-	err = newPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
+	err = firewall.NewPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// A good UDP packet with an AH header
@@ -318,7 +318,7 @@ func Test_newPacket_v6(t *testing.T) {
 	b = append(b, ahb...)
 	b = append(b, udpHeader...)
 
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -328,12 +328,12 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Ensure buffer bounds checking during processing
-	err = newPacket(b[:41], true, p)
+	err = firewall.NewPacket(b[:41], true, p)
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// Invalid AH header
 	b = buffer.Bytes()
-	err = newPacket(b, true, p)
+	err = firewall.NewPacket(b, true, p)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 }
 
@@ -381,7 +381,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	firstFrag = append(firstFrag, []byte{0xde, 0xad, 0xbe, 0xef}...)
 
 	// Test first fragment incoming
-	err = newPacket(firstFrag, true, p)
+	err = firewall.NewPacket(firstFrag, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
@@ -391,7 +391,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Test first fragment outgoing
-	err = newPacket(firstFrag, false, p)
+	err = firewall.NewPacket(firstFrag, false, p)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.RemoteAddr)
@@ -420,7 +420,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	secondFrag = append(secondFrag, []byte{0xde, 0xad, 0xbe, 0xef}...)
 
 	// Test second fragment incoming
-	err = newPacket(secondFrag, true, p)
+	err = firewall.NewPacket(secondFrag, true, p)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
@@ -430,7 +430,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	assert.True(t, p.Fragment)
 
 	// Test second fragment outgoing
-	err = newPacket(secondFrag, false, p)
+	err = firewall.NewPacket(secondFrag, false, p)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.RemoteAddr)
@@ -440,7 +440,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	assert.True(t, p.Fragment)
 
 	// Too short of a fragment packet
-	err = newPacket(secondFrag[:len(secondFrag)-10], false, p)
+	err = firewall.NewPacket(secondFrag[:len(secondFrag)-10], false, p)
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 }
 

overlay/device.go

@@ -7,26 +7,12 @@ import (
 	"github.com/slackhq/nebula/routing"
 )
 
-// BatchReadWriter extends io.ReadWriteCloser with batch I/O operations
-type BatchReadWriter interface {
-	io.ReadWriteCloser
-
-	// BatchRead reads multiple packets at once
-	BatchRead(bufs [][]byte, sizes []int) (int, error)
-
-	// WriteBatch writes multiple packets at once
-	WriteBatch(bufs [][]byte, offset int) (int, error)
-
-	// BatchSize returns the optimal batch size for this device
-	BatchSize() int
-}
-
 type Device interface {
-	BatchReadWriter
+	io.ReadWriteCloser
 	Activate() error
 	Networks() []netip.Prefix
 	Name() string
 	RoutesFor(netip.Addr) routing.Gateways
 	SupportsMultiqueue() bool
-	NewMultiQueueReader() (BatchReadWriter, error)
+	NewMultiQueueReader() (io.ReadWriteCloser, error)
 }

overlay/tun.go

@@ -11,7 +11,6 @@ import (
 )
 
 const DefaultMTU = 1300
-const VirtioNetHdrLen = 10 // Size of virtio_net_hdr structure
 
 type NameError struct {
 	Name       string

overlay/tun_android.go

@@ -99,29 +99,6 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for android")
 }
-
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-func (t *tun) BatchSize() int {
-	return 1
-}

overlay/tun_darwin.go

@@ -553,32 +553,6 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for darwin")
 }
-
-// BatchRead reads a single packet (batch size 1 for non-Linux platforms)
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-// WriteBatch writes packets individually (no batching for non-Linux platforms)
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-// BatchSize returns 1 for non-Linux platforms (no batching)
-func (t *tun) BatchSize() int {
-	return 1
-}

overlay/tun_disabled.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/rcrowley/go-metrics"
 	"github.com/sirupsen/logrus"
+	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/iputil"
 	"github.com/slackhq/nebula/routing"
 )
@@ -87,21 +88,45 @@ func (t *disabledTun) handleICMPEchoRequest(b []byte) bool {
 	default:
 		t.l.Debugf("tun_disabled: dropped ICMP Echo Reply response")
 	}
-
+	if t.l.Level >= logrus.DebugLevel {
+		t.l.WithField("raw", prettyPacket(b)).Debugf("Disabled tun responded to ICMP Echo Request")
+	}
 	return true
 }
 
+func (t *disabledTun) handleOtherPackets(b []byte) error {
+	fp := &firewall.Packet{}
+	err := firewall.NewPacket(b, true, fp)
+	if err != nil {
+		return err
+	}
+	out := make([]byte, len(b)) //todo do something!
+
+	// attempt to write it, but don't block
+	select {
+	case t.read <- out:
+	default:
+		t.l.Debugf("tun_disabled: dropped reply")
+	}
+
+	return err
+}
+
 func (t *disabledTun) Write(b []byte) (int, error) {
 	t.rx.Inc(1)
-
-	// Check for ICMP Echo Request before spending time doing the full parsing
 	if t.handleICMPEchoRequest(b) {
+		return len(b), nil
+	}
+	if err := t.handleOtherPackets(b); err != nil {
 		if t.l.Level >= logrus.DebugLevel {
-			t.l.WithField("raw", prettyPacket(b)).Debugf("Disabled tun responded to ICMP Echo Request")
+			t.l.WithField("raw", prettyPacket(b)).WithError(err).Debugf("Disabled tun failed to respond")
 		}
-	} else if t.l.Level >= logrus.DebugLevel {
+		return len(b), nil
+	}
+	if t.l.Level >= logrus.DebugLevel {
 		t.l.WithField("raw", prettyPacket(b)).Debugf("Disabled tun received unexpected payload")
 	}
+
 	return len(b), nil
 }
 
@@ -109,36 +134,10 @@ func (t *disabledTun) SupportsMultiqueue() bool {
 	return true
 }
 
-func (t *disabledTun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *disabledTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return t, nil
 }
 
-// BatchRead reads a single packet (batch size 1 for disabled tun)
-func (t *disabledTun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-// WriteBatch writes packets individually (no batching for disabled tun)
-func (t *disabledTun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-// BatchSize returns 1 for disabled tun (no batching)
-func (t *disabledTun) BatchSize() int {
-	return 1
-}
-
 func (t *disabledTun) Close() error {
 	if t.read != nil {
 		close(t.read)

overlay/tun_freebsd.go

@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"io"
 	"io/fs"
 	"net/netip"
 	"sync/atomic"
@@ -453,36 +454,10 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for freebsd")
 }
 
-// BatchRead reads a single packet (batch size 1 for FreeBSD)
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-// WriteBatch writes packets individually (no batching for FreeBSD)
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-// BatchSize returns 1 for FreeBSD (no batching)
-func (t *tun) BatchSize() int {
-	return 1
-}
-
 func (t *tun) addRoutes(logErrors bool) error {
 	routes := *t.Routes.Load()
 	for _, r := range routes {

overlay/tun_ios.go

@@ -155,29 +155,6 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for ios")
 }
-
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-func (t *tun) BatchSize() int {
-	return 1
-}

overlay/tun_linux.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/netip"
 	"os"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -21,12 +22,10 @@ import (
 	"github.com/slackhq/nebula/util"
 	"github.com/vishvananda/netlink"
 	"golang.org/x/sys/unix"
-	wgtun "golang.zx2c4.com/wireguard/tun"
 )
 
 type tun struct {
 	io.ReadWriteCloser
-	wgDevice    wgtun.Device
 	fd          int
 	Device      string
 	vpnNetworks []netip.Prefix
@@ -72,154 +71,63 @@ type ifreqQLEN struct {
 	pad   [8]byte
 }
 
-// wgDeviceWrapper wraps a wireguard Device to implement io.ReadWriteCloser
-// This allows multiqueue readers to use the same wireguard Device batching as the main device
-type wgDeviceWrapper struct {
-	dev wgtun.Device
-	buf []byte // Reusable buffer for single packet reads
-}
-
-func (w *wgDeviceWrapper) Read(b []byte) (int, error) {
-	// Use wireguard Device's batch API for single packet
-	bufs := [][]byte{b}
-	sizes := make([]int, 1)
-	n, err := w.dev.Read(bufs, sizes, 0)
-	if err != nil {
-		return 0, err
-	}
-	if n == 0 {
-		return 0, io.EOF
-	}
-	return sizes[0], nil
-}
-
-func (w *wgDeviceWrapper) Write(b []byte) (int, error) {
-	// Buffer b should have virtio header space (10 bytes) at the beginning
-	// The decrypted packet data starts at offset 10
-	// Pass the full buffer to WireGuard with offset=virtioNetHdrLen
-	bufs := [][]byte{b}
-	n, err := w.dev.Write(bufs, VirtioNetHdrLen)
-	if err != nil {
-		return 0, err
-	}
-	if n == 0 {
-		return 0, io.ErrShortWrite
-	}
-	return len(b), nil
-}
-
-func (w *wgDeviceWrapper) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	// Pass all buffers to WireGuard's batch write
-	return w.dev.Write(bufs, offset)
-}
-
-func (w *wgDeviceWrapper) Close() error {
-	return w.dev.Close()
-}
-
-// BatchRead implements batching for multiqueue readers
-func (w *wgDeviceWrapper) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	// The zero here is offset.
-	return w.dev.Read(bufs, sizes, 0)
-}
-
-// BatchSize returns the optimal batch size
-func (w *wgDeviceWrapper) BatchSize() int {
-	return w.dev.BatchSize()
-}
-
 func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
-	wgDev, name, err := wgtun.CreateUnmonitoredTUNFromFD(deviceFd)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create TUN from FD: %w", err)
-	}
+	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
-	file := wgDev.File()
 	t, err := newTunGeneric(c, l, file, vpnNetworks)
 	if err != nil {
-		_ = wgDev.Close()
 		return nil, err
 	}
 
-	t.wgDevice = wgDev
-	t.Device = name
+	t.Device = "tun0"
 
 	return t, nil
 }
 
 func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, multiqueue bool) (*tun, error) {
-	// Check if /dev/net/tun exists, create if needed (for docker containers)
-	if _, err := os.Stat("/dev/net/tun"); os.IsNotExist(err) {
-		if err := os.MkdirAll("/dev/net", 0755); err != nil {
-			return nil, fmt.Errorf("/dev/net/tun doesn't exist, failed to mkdir -p /dev/net: %w", err)
-		}
-		if err := unix.Mknod("/dev/net/tun", unix.S_IFCHR|0600, int(unix.Mkdev(10, 200))); err != nil {
-			return nil, fmt.Errorf("failed to create /dev/net/tun: %w", err)
-		}
-	}
-
-	devName := c.GetString("tun.dev", "")
-	mtu := c.GetInt("tun.mtu", DefaultMTU)
-
-	// Create TUN device manually to support multiqueue
 	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
-		return nil, err
+		// If /dev/net/tun doesn't exist, try to create it (will happen in docker)
+		if os.IsNotExist(err) {
+			err = os.MkdirAll("/dev/net", 0755)
+			if err != nil {
+				return nil, fmt.Errorf("/dev/net/tun doesn't exist, failed to mkdir -p /dev/net: %w", err)
+			}
+			err = unix.Mknod("/dev/net/tun", unix.S_IFCHR|0600, int(unix.Mkdev(10, 200)))
+			if err != nil {
+				return nil, fmt.Errorf("failed to create /dev/net/tun: %w", err)
+			}
+
+			fd, err = unix.Open("/dev/net/tun", os.O_RDWR, 0)
+			if err != nil {
+				return nil, fmt.Errorf("created /dev/net/tun, but still failed: %w", err)
+			}
+		} else {
+			return nil, err
+		}
 	}
 
 	var req ifReq
-	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI | unix.IFF_VNET_HDR)
+	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI)
 	if multiqueue {
 		req.Flags |= unix.IFF_MULTI_QUEUE
 	}
-	copy(req.Name[:], devName)
+	nameStr := c.GetString("tun.dev", "")
+	copy(req.Name[:], nameStr)
 	if err = ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
-		unix.Close(fd)
-		return nil, err
-	}
-
-	// Set nonblocking
-	if err = unix.SetNonblock(fd, true); err != nil {
-		unix.Close(fd)
-		return nil, err
-	}
-
-	// Enable TCP and UDP offload (TSO/GRO) for performance
-	// This allows the kernel to handle segmentation/coalescing
-	const (
-		tunTCPOffloads = unix.TUN_F_CSUM | unix.TUN_F_TSO4 | unix.TUN_F_TSO6
-		tunUDPOffloads = unix.TUN_F_USO4 | unix.TUN_F_USO6
-	)
-	offloads := tunTCPOffloads | tunUDPOffloads
-	if err = unix.IoctlSetInt(fd, unix.TUNSETOFFLOAD, offloads); err != nil {
-		// Log warning but don't fail - offload is optional
-		l.WithError(err).Warn("Failed to enable TUN offload (TSO/GRO), performance may be reduced")
+		return nil, &NameError{
+			Name:       nameStr,
+			Underlying: err,
+		}
 	}
+	name := strings.Trim(string(req.Name[:]), "\x00")
 
 	file := os.NewFile(uintptr(fd), "/dev/net/tun")
-
-	// Create wireguard device from file descriptor
-	wgDev, err := wgtun.CreateTUNFromFile(file, mtu)
-	if err != nil {
-		file.Close()
-		return nil, fmt.Errorf("failed to create TUN from file: %w", err)
-	}
-
-	name, err := wgDev.Name()
-	if err != nil {
-		_ = wgDev.Close()
-		return nil, fmt.Errorf("failed to get TUN device name: %w", err)
-	}
-
-	// file is now owned by wgDev, get a new reference
-	file = wgDev.File()
 	t, err := newTunGeneric(c, l, file, vpnNetworks)
 	if err != nil {
-		_ = wgDev.Close()
 		return nil, err
 	}
 
-	t.wgDevice = wgDev
 	t.Device = name
 
 	return t, nil
@@ -330,44 +238,22 @@ func (t *tun) SupportsMultiqueue() bool {
 	return true
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
 
 	var req ifReq
-	// MUST match the flags used in newTun - includes IFF_VNET_HDR
-	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI | unix.IFF_VNET_HDR | unix.IFF_MULTI_QUEUE)
+	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI | unix.IFF_MULTI_QUEUE)
 	copy(req.Name[:], t.Device)
 	if err = ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
-		unix.Close(fd)
 		return nil, err
 	}
 
-	// Set nonblocking mode - CRITICAL for proper netpoller integration
-	if err = unix.SetNonblock(fd, true); err != nil {
-		unix.Close(fd)
-		return nil, err
-	}
-
-	// Get MTU from main device
-	mtu := t.MaxMTU
-	if mtu == 0 {
-		mtu = DefaultMTU
-	}
-
 	file := os.NewFile(uintptr(fd), "/dev/net/tun")
 
-	// Create wireguard Device from the file descriptor (just like the main device)
-	wgDev, err := wgtun.CreateTUNFromFile(file, mtu)
-	if err != nil {
-		file.Close()
-		return nil, fmt.Errorf("failed to create multiqueue TUN device: %w", err)
-	}
-
-	// Return a wrapper that uses the wireguard Device for all I/O
-	return &wgDeviceWrapper{dev: wgDev}, nil
+	return file, nil
 }
 
 func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
@@ -375,68 +261,7 @@ func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
 	return r
 }
 
-func (t *tun) Read(b []byte) (int, error) {
-	if t.wgDevice != nil {
-		// Use wireguard device which handles virtio headers internally
-		bufs := [][]byte{b}
-		sizes := make([]int, 1)
-		n, err := t.wgDevice.Read(bufs, sizes, 0)
-		if err != nil {
-			return 0, err
-		}
-		if n == 0 {
-			return 0, io.EOF
-		}
-		return sizes[0], nil
-	}
-
-	// Fallback: direct read from file (shouldn't happen in normal operation)
-	return t.ReadWriteCloser.Read(b)
-}
-
-// BatchRead reads multiple packets at once for improved performance
-// bufs: slice of buffers to read into
-// sizes: slice that will be filled with packet sizes
-// Returns number of packets read
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	if t.wgDevice != nil {
-		return t.wgDevice.Read(bufs, sizes, 0)
-	}
-
-	// Fallback: single packet read
-	n, err := t.ReadWriteCloser.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-// BatchSize returns the optimal number of packets to read/write in a batch
-func (t *tun) BatchSize() int {
-	if t.wgDevice != nil {
-		return t.wgDevice.BatchSize()
-	}
-	return 1
-}
-
 func (t *tun) Write(b []byte) (int, error) {
-	if t.wgDevice != nil {
-		// Buffer b should have virtio header space (10 bytes) at the beginning
-		// The decrypted packet data starts at offset 10
-		// Pass the full buffer to WireGuard with offset=virtioNetHdrLen
-		bufs := [][]byte{b}
-		n, err := t.wgDevice.Write(bufs, VirtioNetHdrLen)
-		if err != nil {
-			return 0, err
-		}
-		if n == 0 {
-			return 0, io.ErrShortWrite
-		}
-		return len(b), nil
-	}
-
-	// Fallback: direct write (shouldn't happen in normal operation)
 	var nn int
 	maximum := len(b)
 
@@ -459,22 +284,6 @@ func (t *tun) Write(b []byte) (int, error) {
 	}
 }
 
-// WriteBatch writes multiple packets to the TUN device in a single syscall
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	if t.wgDevice != nil {
-		return t.wgDevice.Write(bufs, offset)
-	}
-
-	// Fallback: write individually (shouldn't happen in normal operation)
-	for i, buf := range bufs {
-		_, err := t.Write(buf)
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
 func (t *tun) deviceBytes() (o [16]byte) {
 	for i, c := range t.Device {
 		o[i] = byte(c)
@@ -902,10 +711,6 @@ func (t *tun) Close() error {
 		close(t.routeChan)
 	}
 
-	if t.wgDevice != nil {
-		_ = t.wgDevice.Close()
-	}
-
 	if t.ReadWriteCloser != nil {
 		_ = t.ReadWriteCloser.Close()
 	}

overlay/tun_netbsd.go

@@ -6,6 +6,7 @@ package overlay
 import (
 	"errors"
 	"fmt"
+	"io"
 	"net/netip"
 	"os"
 	"regexp"
@@ -393,33 +394,10 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for netbsd")
 }
 
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-func (t *tun) BatchSize() int {
-	return 1
-}
-
 func (t *tun) addRoutes(logErrors bool) error {
 	routes := *t.Routes.Load()
 

overlay/tun_openbsd.go

@@ -6,6 +6,7 @@ package overlay
 import (
 	"errors"
 	"fmt"
+	"io"
 	"net/netip"
 	"os"
 	"regexp"
@@ -313,33 +314,10 @@ func (t *tun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *tun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for openbsd")
 }
 
-func (t *tun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-func (t *tun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-func (t *tun) BatchSize() int {
-	return 1
-}
-
 func (t *tun) addRoutes(logErrors bool) error {
 	routes := *t.Routes.Load()
 

overlay/tun_tester.go

@@ -109,12 +109,8 @@ func (t *TestTun) Write(b []byte) (n int, err error) {
 		return 0, io.ErrClosedPipe
 	}
 
-	// Skip virtio header (consistent with production Linux tun)
-	// The buffer b has VirtioNetHdrLen bytes of header followed by the actual packet
-	data := b[VirtioNetHdrLen:]
-
-	packet := make([]byte, len(data))
-	copy(packet, data)
+	packet := make([]byte, len(b), len(b))
+	copy(packet, b)
 	t.TxPackets <- packet
 	return len(b), nil
 }
@@ -140,34 +136,6 @@ func (t *TestTun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *TestTun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *TestTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented")
 }
-
-func (t *TestTun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-func (t *TestTun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	if t.closed.Load() {
-		return 0, io.ErrClosedPipe
-	}
-
-	for _, buf := range bufs {
-		// Strip the header at offset and send directly to channel
-		data := buf[offset:]
-		packet := make([]byte, len(data))
-		copy(packet, data)
-		t.TxPackets <- packet
-	}
-	return len(bufs), nil
-}
-
-func (t *TestTun) BatchSize() int {
-	return 1
-}

overlay/tun_windows.go

@@ -6,6 +6,7 @@ package overlay
 import (
 	"crypto"
 	"fmt"
+	"io"
 	"net/netip"
 	"os"
 	"path/filepath"
@@ -240,36 +241,10 @@ func (t *winTun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *winTun) NewMultiQueueReader() (BatchReadWriter, error) {
+func (t *winTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
 }
 
-// BatchRead reads a single packet (batch size 1 for Windows)
-func (t *winTun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := t.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-// WriteBatch writes packets individually (no batching for Windows)
-func (t *winTun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := t.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-// BatchSize returns 1 for Windows (no batching)
-func (t *winTun) BatchSize() int {
-	return 1
-}
-
 func (t *winTun) Close() error {
 	// It seems that the Windows networking stack doesn't like it when we destroy interfaces that have active routes,
 	// so to be certain, just remove everything before destroying.

overlay/user.go

@@ -50,36 +50,10 @@ func (d *UserDevice) SupportsMultiqueue() bool {
 	return true
 }
 
-func (d *UserDevice) NewMultiQueueReader() (BatchReadWriter, error) {
+func (d *UserDevice) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return d, nil
 }
 
-// BatchRead reads a single packet (batch size 1 for UserDevice)
-func (d *UserDevice) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	n, err := d.Read(bufs[0])
-	if err != nil {
-		return 0, err
-	}
-	sizes[0] = n
-	return 1, nil
-}
-
-// WriteBatch writes packets individually (no batching for UserDevice)
-func (d *UserDevice) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	for i, buf := range bufs {
-		_, err := d.Write(buf[offset:])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(bufs), nil
-}
-
-// BatchSize returns 1 for UserDevice (no batching)
-func (d *UserDevice) BatchSize() int {
-	return 1
-}
-
 func (d *UserDevice) Pipe() (*io.PipeReader, *io.PipeWriter) {
 	return d.inboundReader, d.outboundWriter
 }

stats.go

@@ -6,7 +6,6 @@ import (
 	"log"
 	"net"
 	"net/http"
-	_ "net/http/pprof"
 	"runtime"
 	"strconv"
 	"time"

test/tun.go

@@ -1,11 +1,10 @@
-package device
+package test
 
 import (
 	"errors"
 	"io"
 	"net/netip"
 
-	"github.com/slackhq/nebula/overlay"
 	"github.com/slackhq/nebula/routing"
 )
 
@@ -39,25 +38,10 @@ func (NoopTun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (NoopTun) NewMultiQueueReader() (overlay.BatchReadWriter, error) {
+func (NoopTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, errors.New("unsupported")
 }
 
 func (NoopTun) Close() error {
 	return nil
 }
-
-// BatchRead implements BatchReadWriter interface
-func (NoopTun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
-	return 0, io.EOF
-}
-
-// WriteBatch implements BatchReadWriter interface
-func (NoopTun) WriteBatch(bufs [][]byte, offset int) (int, error) {
-	return len(bufs), nil
-}
-
-// BatchSize implements BatchReadWriter interface
-func (NoopTun) BatchSize() int {
-	return 1
-}

udp/conn.go

@@ -13,21 +13,13 @@ type EncReader func(
 	payload []byte,
 )
 
-type EncBatchReader func(
-	addrs []netip.AddrPort,
-	payloads [][]byte,
-	count int,
-)
-
 type Conn interface {
 	Rebind() error
 	LocalAddr() (netip.AddrPort, error)
-	ListenOutBatch(r EncBatchReader)
+	ListenOut(r EncReader)
 	WriteTo(b []byte, addr netip.AddrPort) error
-	WriteMulti(packets [][]byte, addrs []netip.AddrPort) (int, error)
 	ReloadConfig(c *config.C)
 	SupportsMultipleReaders() bool
-	BatchSize() int
 	Close() error
 }
 
@@ -39,25 +31,17 @@ func (NoopConn) Rebind() error {
 func (NoopConn) LocalAddr() (netip.AddrPort, error) {
 	return netip.AddrPort{}, nil
 }
-
-func (NoopConn) ListenOut(_ EncReader) {}
-
+func (NoopConn) ListenOut(_ EncReader) {
+	return
+}
 func (NoopConn) SupportsMultipleReaders() bool {
 	return false
 }
-
-func (NoopConn) ListenOutBatch(_ EncBatchReader) {}
-
 func (NoopConn) WriteTo(_ []byte, _ netip.AddrPort) error {
 	return nil
 }
-func (NoopConn) WriteMulti(_ [][]byte, _ []netip.AddrPort) (int, error) {
-	return 0, nil
-}
-func (NoopConn) ReloadConfig(_ *config.C) {}
-
-func (NoopConn) BatchSize() int {
-	return 1
+func (NoopConn) ReloadConfig(_ *config.C) {
+	return
 }
 func (NoopConn) Close() error {
 	return nil

udp/udp_darwin.go

@@ -140,17 +140,6 @@ func (u *StdConn) WriteTo(b []byte, ap netip.AddrPort) error {
 	}
 }
 
-// WriteMulti sends multiple packets - fallback implementation without sendmmsg
-func (u *StdConn) WriteMulti(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	for i := range packets {
-		err := u.WriteTo(packets[i], addrs[i])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(packets), nil
-}
-
 func (u *StdConn) LocalAddr() (netip.AddrPort, error) {
 	a := u.UDPConn.LocalAddr()
 
@@ -199,34 +188,6 @@ func (u *StdConn) SupportsMultipleReaders() bool {
 	return false
 }
 
-// ListenOutBatch - fallback to single-packet reads for Darwin
-func (u *StdConn) ListenOutBatch(r EncBatchReader) {
-	buffer := make([]byte, MTU)
-	addrs := make([]netip.AddrPort, 1)
-	payloads := make([][]byte, 1)
-
-	for {
-		// Just read one packet at a time and call batch callback with count=1
-		n, rua, err := u.ReadFromUDPAddrPort(buffer)
-		if err != nil {
-			if errors.Is(err, net.ErrClosed) {
-				u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-				return
-			}
-
-			u.l.WithError(err).Error("unexpected udp socket receive error")
-		}
-
-		addrs[0] = netip.AddrPortFrom(rua.Addr().Unmap(), rua.Port())
-		payloads[0] = buffer[:n]
-		r(addrs, payloads, 1)
-	}
-}
-
-func (u *StdConn) BatchSize() int {
-	return 1
-}
-
 func (u *StdConn) Rebind() error {
 	var err error
 	if u.isV4 {

udp/udp_generic.go

@@ -101,38 +101,3 @@ func (u *GenericConn) ListenOut(r EncReader) {
 func (u *GenericConn) SupportsMultipleReaders() bool {
 	return false
 }
-
-// ListenOutBatch - fallback to single-packet reads for generic platforms
-func (u *GenericConn) ListenOutBatch(r EncBatchReader) {
-	buffer := make([]byte, MTU)
-	addrs := make([]netip.AddrPort, 1)
-	payloads := make([][]byte, 1)
-
-	for {
-		// Just read one packet at a time and call batch callback with count=1
-		n, rua, err := u.ReadFromUDPAddrPort(buffer)
-		if err != nil {
-			u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-			return
-		}
-
-		addrs[0] = netip.AddrPortFrom(rua.Addr().Unmap(), rua.Port())
-		payloads[0] = buffer[:n]
-		r(addrs, payloads, 1)
-	}
-}
-
-// WriteMulti sends multiple packets - fallback implementation
-func (u *GenericConn) WriteMulti(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	for i := range packets {
-		err := u.WriteTo(packets[i], addrs[i])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(packets), nil
-}
-
-func (u *GenericConn) BatchSize() int {
-	return 1
-}

udp/udp_linux.go

@@ -22,11 +22,6 @@ type StdConn struct {
 	isV4  bool
 	l     *logrus.Logger
 	batch int
-
-	// Pre-allocated buffers for batch writes (sized for IPv6, works for both)
-	writeMsgs   []rawMessage
-	writeIovecs []iovec
-	writeNames  [][]byte
 }
 
 func maybeIPV4(ip net.IP) (net.IP, bool) {
@@ -74,26 +69,7 @@ func NewListener(l *logrus.Logger, ip netip.Addr, port int, multi bool, batch in
 		return nil, fmt.Errorf("unable to bind to socket: %s", err)
 	}
 
-	c := &StdConn{sysFd: fd, isV4: ip.Is4(), l: l, batch: batch}
-
-	// Pre-allocate write message structures for batching (sized for IPv6, works for both)
-	c.writeMsgs = make([]rawMessage, batch)
-	c.writeIovecs = make([]iovec, batch)
-	c.writeNames = make([][]byte, batch)
-
-	for i := range c.writeMsgs {
-		// Allocate for IPv6 size (larger than IPv4, works for both)
-		c.writeNames[i] = make([]byte, unix.SizeofSockaddrInet6)
-
-		// Point to the iovec in the slice
-		c.writeMsgs[i].Hdr.Iov = &c.writeIovecs[i]
-		c.writeMsgs[i].Hdr.Iovlen = 1
-
-		c.writeMsgs[i].Hdr.Name = &c.writeNames[i][0]
-		// Namelen will be set appropriately in writeMulti4/writeMulti6
-	}
-
-	return c, err
+	return &StdConn{sysFd: fd, isV4: ip.Is4(), l: l, batch: batch}, err
 }
 
 func (u *StdConn) SupportsMultipleReaders() bool {
@@ -146,7 +122,7 @@ func (u *StdConn) LocalAddr() (netip.AddrPort, error) {
 	}
 }
 
-func (u *StdConn) ListenOutBatch(r EncBatchReader) {
+func (u *StdConn) ListenOut(r EncReader) {
 	var ip netip.Addr
 
 	msgs, buffers, names := u.PrepareRawMessages(u.batch)
@@ -155,12 +131,6 @@ func (u *StdConn) ListenOutBatch(r EncBatchReader) {
 		read = u.ReadSingle
 	}
 
-	udpBatchHist := metrics.GetOrRegisterHistogram("batch.udp_read_size", nil, metrics.NewUniformSample(1024))
-
-	// Pre-allocate slices for batch callback
-	addrs := make([]netip.AddrPort, u.batch)
-	payloads := make([][]byte, u.batch)
-
 	for {
 		n, err := read(msgs)
 		if err != nil {
@@ -168,21 +138,15 @@ func (u *StdConn) ListenOutBatch(r EncBatchReader) {
 			return
 		}
 
-		udpBatchHist.Update(int64(n))
-
-		// Prepare batch data
 		for i := 0; i < n; i++ {
+			// Its ok to skip the ok check here, the slicing is the only error that can occur and it will panic
 			if u.isV4 {
 				ip, _ = netip.AddrFromSlice(names[i][4:8])
 			} else {
 				ip, _ = netip.AddrFromSlice(names[i][8:24])
 			}
-			addrs[i] = netip.AddrPortFrom(ip.Unmap(), binary.BigEndian.Uint16(names[i][2:4]))
-			payloads[i] = buffers[i][:msgs[i].Len]
+			r(netip.AddrPortFrom(ip.Unmap(), binary.BigEndian.Uint16(names[i][2:4])), buffers[i][:msgs[i].Len])
 		}
-
-		// Call batch callback with all packets
-		r(addrs, payloads, n)
 	}
 }
 
@@ -234,19 +198,6 @@ func (u *StdConn) WriteTo(b []byte, ip netip.AddrPort) error {
 	return u.writeTo6(b, ip)
 }
 
-func (u *StdConn) WriteMulti(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	if len(packets) != len(addrs) {
-		return 0, fmt.Errorf("packets and addrs length mismatch")
-	}
-	if len(packets) == 0 {
-		return 0, nil
-	}
-	if u.isV4 {
-		return u.writeMulti4(packets, addrs)
-	}
-	return u.writeMulti6(packets, addrs)
-}
-
 func (u *StdConn) writeTo6(b []byte, ip netip.AddrPort) error {
 	var rsa unix.RawSockaddrInet6
 	rsa.Family = unix.AF_INET6
@@ -301,123 +252,6 @@ func (u *StdConn) writeTo4(b []byte, ip netip.AddrPort) error {
 	}
 }
 
-func (u *StdConn) writeMulti4(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	sent := 0
-	for sent < len(packets) {
-		// Determine batch size based on remaining packets and buffer capacity
-		batchSize := len(packets) - sent
-		if batchSize > len(u.writeMsgs) {
-			batchSize = len(u.writeMsgs)
-		}
-
-		// Use pre-allocated buffers
-		msgs := u.writeMsgs[:batchSize]
-		iovecs := u.writeIovecs[:batchSize]
-		names := u.writeNames[:batchSize]
-
-		// Setup message structures for this batch
-		for i := 0; i < batchSize; i++ {
-			pktIdx := sent + i
-			if !addrs[pktIdx].Addr().Is4() {
-				return sent + i, ErrInvalidIPv6RemoteForSocket
-			}
-
-			// Setup the packet buffer
-			iovecs[i].Base = &packets[pktIdx][0]
-			iovecs[i].Len = uint(len(packets[pktIdx]))
-
-			// Setup the destination address
-			rsa := (*unix.RawSockaddrInet4)(unsafe.Pointer(&names[i][0]))
-			rsa.Family = unix.AF_INET
-			rsa.Addr = addrs[pktIdx].Addr().As4()
-			binary.BigEndian.PutUint16((*[2]byte)(unsafe.Pointer(&rsa.Port))[:], addrs[pktIdx].Port())
-
-			// Set the appropriate address length for IPv4
-			msgs[i].Hdr.Namelen = unix.SizeofSockaddrInet4
-		}
-
-		// Send this batch
-		nsent, _, err := unix.Syscall6(
-			unix.SYS_SENDMMSG,
-			uintptr(u.sysFd),
-			uintptr(unsafe.Pointer(&msgs[0])),
-			uintptr(batchSize),
-			0,
-			0,
-			0,
-		)
-
-		if err != 0 {
-			return sent + int(nsent), &net.OpError{Op: "sendmmsg", Err: err}
-		}
-
-		sent += int(nsent)
-		if int(nsent) < batchSize {
-			// Couldn't send all packets in batch, return what we sent
-			return sent, nil
-		}
-	}
-
-	return sent, nil
-}
-
-func (u *StdConn) writeMulti6(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	sent := 0
-	for sent < len(packets) {
-		// Determine batch size based on remaining packets and buffer capacity
-		batchSize := len(packets) - sent
-		if batchSize > len(u.writeMsgs) {
-			batchSize = len(u.writeMsgs)
-		}
-
-		// Use pre-allocated buffers
-		msgs := u.writeMsgs[:batchSize]
-		iovecs := u.writeIovecs[:batchSize]
-		names := u.writeNames[:batchSize]
-
-		// Setup message structures for this batch
-		for i := 0; i < batchSize; i++ {
-			pktIdx := sent + i
-
-			// Setup the packet buffer
-			iovecs[i].Base = &packets[pktIdx][0]
-			iovecs[i].Len = uint(len(packets[pktIdx]))
-
-			// Setup the destination address
-			rsa := (*unix.RawSockaddrInet6)(unsafe.Pointer(&names[i][0]))
-			rsa.Family = unix.AF_INET6
-			rsa.Addr = addrs[pktIdx].Addr().As16()
-			binary.BigEndian.PutUint16((*[2]byte)(unsafe.Pointer(&rsa.Port))[:], addrs[pktIdx].Port())
-
-			// Set the appropriate address length for IPv6
-			msgs[i].Hdr.Namelen = unix.SizeofSockaddrInet6
-		}
-
-		// Send this batch
-		nsent, _, err := unix.Syscall6(
-			unix.SYS_SENDMMSG,
-			uintptr(u.sysFd),
-			uintptr(unsafe.Pointer(&msgs[0])),
-			uintptr(batchSize),
-			0,
-			0,
-			0,
-		)
-
-		if err != 0 {
-			return sent + int(nsent), &net.OpError{Op: "sendmmsg", Err: err}
-		}
-
-		sent += int(nsent)
-		if int(nsent) < batchSize {
-			// Couldn't send all packets in batch, return what we sent
-			return sent, nil
-		}
-	}
-
-	return sent, nil
-}
-
 func (u *StdConn) ReloadConfig(c *config.C) {
 	b := c.GetInt("listen.read_buffer", 0)
 	if b > 0 {
@@ -475,10 +309,6 @@ func (u *StdConn) getMemInfo(meminfo *[unix.SK_MEMINFO_VARS]uint32) error {
 	return nil
 }
 
-func (u *StdConn) BatchSize() int {
-	return u.batch
-}
-
 func (u *StdConn) Close() error {
 	return syscall.Close(u.sysFd)
 }

udp/udp_linux_32.go

@@ -12,7 +12,7 @@ import (
 
 type iovec struct {
 	Base *byte
-	Len  uint
+	Len  uint32
 }
 
 type msghdr struct {
@@ -40,7 +40,7 @@ func (u *StdConn) PrepareRawMessages(n int) ([]rawMessage, [][]byte, [][]byte) {
 		names[i] = make([]byte, unix.SizeofSockaddrInet6)
 
 		vs := []iovec{
-			{Base: &buffers[i][0], Len: uint(len(buffers[i]))},
+			{Base: &buffers[i][0], Len: uint32(len(buffers[i]))},
 		}
 
 		msgs[i].Hdr.Iov = &vs[0]

udp/udp_linux_64.go

@@ -12,7 +12,7 @@ import (
 
 type iovec struct {
 	Base *byte
-	Len  uint
+	Len  uint64
 }
 
 type msghdr struct {
@@ -43,7 +43,7 @@ func (u *StdConn) PrepareRawMessages(n int) ([]rawMessage, [][]byte, [][]byte) {
 		names[i] = make([]byte, unix.SizeofSockaddrInet6)
 
 		vs := []iovec{
-			{Base: &buffers[i][0], Len: uint(len(buffers[i]))},
+			{Base: &buffers[i][0], Len: uint64(len(buffers[i]))},
 		}
 
 		msgs[i].Hdr.Iov = &vs[0]

udp/udp_rio_windows.go

@@ -338,50 +338,6 @@ func (u *RIOConn) Rebind() error {
 
 func (u *RIOConn) ReloadConfig(*config.C) {}
 
-// BatchSize returns 1 since RIO reads packets one at a time
-func (u *RIOConn) BatchSize() int {
-	return 1
-}
-
-// ListenOutBatch - fallback to single-packet reads for RIO
-func (u *RIOConn) ListenOutBatch(r EncBatchReader) {
-	buffer := make([]byte, MTU)
-	addrs := make([]netip.AddrPort, 1)
-	payloads := make([][]byte, 1)
-
-	var lastRecvErr time.Time
-
-	for {
-		n, rua, err := u.receive(buffer)
-		if err != nil {
-			if errors.Is(err, net.ErrClosed) {
-				u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-				return
-			}
-			if lastRecvErr.IsZero() || time.Since(lastRecvErr) > time.Minute {
-				lastRecvErr = time.Now()
-				u.l.WithError(err).Warn("unexpected udp socket receive error")
-			}
-			continue
-		}
-
-		addrs[0] = netip.AddrPortFrom(netip.AddrFrom16(rua.Addr).Unmap(), (rua.Port>>8)|((rua.Port&0xff)<<8))
-		payloads[0] = buffer[:n]
-		r(addrs, payloads, 1)
-	}
-}
-
-// WriteMulti sends multiple packets - fallback implementation
-func (u *RIOConn) WriteMulti(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	for i := range packets {
-		err := u.WriteTo(packets[i], addrs[i])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(packets), nil
-}
-
 func (u *RIOConn) Close() error {
 	if !u.isOpen.CompareAndSwap(true, false) {
 		return nil

udp/udp_tester.go

@@ -116,31 +116,6 @@ func (u *TesterConn) ListenOut(r EncReader) {
 	}
 }
 
-func (u *TesterConn) ListenOutBatch(r EncBatchReader) {
-	addrs := make([]netip.AddrPort, 1)
-	payloads := make([][]byte, 1)
-
-	for {
-		p, ok := <-u.RxPackets
-		if !ok {
-			return
-		}
-		addrs[0] = p.From
-		payloads[0] = p.Data
-		r(addrs, payloads, 1)
-	}
-}
-
-func (u *TesterConn) WriteMulti(packets [][]byte, addrs []netip.AddrPort) (int, error) {
-	for i := range packets {
-		err := u.WriteTo(packets[i], addrs[i])
-		if err != nil {
-			return i, err
-		}
-	}
-	return len(packets), nil
-}
-
 func (u *TesterConn) ReloadConfig(*config.C) {}
 
 func NewUDPStatsEmitter(_ []Conn) func() {
@@ -156,10 +131,6 @@ func (u *TesterConn) SupportsMultipleReaders() bool {
 	return false
 }
 
-func (u *TesterConn) BatchSize() int {
-	return 1
-}
-
 func (u *TesterConn) Rebind() error {
 	return nil
 }