SPICY

firewall/cache_test.go

@@ -23,7 +23,7 @@ func newFixedTicker(t *testing.T, l *slog.Logger, cacheLen int) *ConntrackCacheT
 		cache: make(ConntrackCache, cacheLen),
 	}
 	for i := 0; i < cacheLen; i++ {
-		c.cache[PacketKey{TransportTuple: TransportTuple{LocalPort: uint16(i) + 1}}] = struct{}{}
+		c.cache[PacketKey{LocalPort: uint16(i) + 1}] = struct{}{}
 	}
 	c.cacheTick.Store(1) // cacheV starts at 0, so Get() takes the reset path
 	return c

firewall/packet.go

@@ -19,19 +19,6 @@ const (
 	PortFragment = -1 // Special value for matching `port: fragment`
 )
 
-// TransportTuple is the dense 5-tuple shape shared between the coalescer's
-// flowKey-equivalent and the firewall's PacketKey. Stored in Local/Remote
-// orientation so a flow's incoming and outgoing packets share the same
-// tuple identity. v4 addresses occupy the low 4 bytes of LocalAddr/
-// RemoteAddr (NOT v4-mapped form) so v4 vs v6 tuples never collide.
-type TransportTuple struct {
-	LocalAddr  [16]byte
-	RemoteAddr [16]byte
-	LocalPort  uint16
-	RemotePort uint16
-	IsV6       bool
-}
-
 // PacketKey is the firewall's conntrack and ConntrackCache map key — the
 // dense form of the 5-tuple plus the protocol and fragment flag the
 // firewall actually discriminates flows on. Kept separate from Packet so
@@ -42,9 +29,13 @@ type TransportTuple struct {
 // Superset of the coalescer's flowKey shape (same 5-tuple, just in
 // Local/Remote orientation rather than wire src/dst).
 type PacketKey struct {
-	TransportTuple
-	Protocol uint8
-	Fragment bool
+	LocalAddr  [16]byte
+	RemoteAddr [16]byte
+	LocalPort  uint16
+	RemotePort uint16
+	IsV6       bool
+	Protocol   uint8
+	Fragment   bool
 }
 
 type Packet struct {
@@ -104,6 +95,16 @@ func (k *PacketKey) Hydrate(fp *Packet) {
 	}
 }
 
+func (k *PacketKey) GetRemoteAddr() netip.Addr {
+	if k.IsV6 {
+		return netip.AddrFrom16(k.RemoteAddr)
+	} else {
+		var v4 [4]byte
+		copy(v4[:], k.RemoteAddr[:4])
+		return netip.AddrFrom4(v4)
+	}
+}
+
 func (fp *Packet) Copy() *Packet {
 	return &Packet{
 		LocalAddr:  fp.LocalAddr,

inside.go

@@ -28,7 +28,7 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packe
 	// the same 5-tuple every segment will share, so a single newPacket /
 	// firewall check covers the whole superpacket.
 	packet := pkt.Bytes
-	err := newPacket(packet, false, fwPacket)
+	key, err := newPacketKey(packet, false)
 	if err != nil {
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			f.l.Debug("Error while validating outbound packet",
@@ -39,6 +39,8 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packe
 		return
 	}
 
+	key.Hydrate(fwPacket)
+
 	// Ignore local broadcast packets
 	if f.dropLocalBroadcast {
 		if f.myBroadcastAddrsTable.Contains(fwPacket.RemoteAddr) {
@@ -105,7 +107,7 @@ func (f *Interface) consumeInsidePacket(pkt tio.Packet, fwPacket *firewall.Packe
 		return
 	}
 
-	dropReason := f.firewall.Drop(fwPacket.Key(), fwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
+	dropReason := f.firewall.Drop(key, fwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason == nil {
 		f.sendInsideMessage(hostinfo, pkt, nb, sendBatch, rejectBuf, q)
 	} else {
@@ -392,15 +394,16 @@ func (f *Interface) getOrHandshakeConsiderRouting(fwPacket *firewall.Packet, cac
 }
 
 func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p, nb, out []byte) {
-	fp := &firewall.Packet{}
-	err := newPacket(p, false, fp)
+	key, err := newPacketKey(p, false)
 	if err != nil {
 		f.l.Warn("error while parsing outgoing packet for firewall check", "error", err)
 		return
 	}
+	fp := &firewall.Packet{}
+	key.Hydrate(fp)
 
 	// check if packet is in outbound fw rules
-	dropReason := f.firewall.Drop(fp.Key(), fp, false, hostinfo, f.pki.GetCAPool(), nil)
+	dropReason := f.firewall.Drop(key, fp, false, hostinfo, f.pki.GetCAPool(), nil)
 	if dropReason != nil {
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
 			f.l.Debug("dropping cached packet",

outside.go

@@ -313,37 +313,54 @@ var (
 )
 
 // newPacket validates and parses the interesting bits for the firewall out of the ip and sub protocol headers
+// newPacket parses data into a fully-hydrated firewall.Packet — kept as a
+// thin wrapper around newPacketKey + Hydrate so there's one source of
+// parse logic. Callers that don't need the netip.Addr-rich form (e.g.
+// conntrack-only paths) should use newPacketKey directly.
 func newPacket(data []byte, incoming bool, fp *firewall.Packet) error {
-	if len(data) < 1 {
-		return ErrPacketTooShort
+	key, err := newPacketKey(data, incoming)
+	if err != nil {
+		return err
 	}
+	key.Hydrate(fp)
+	return nil
+}
 
-	version := int((data[0] >> 4) & 0x0f)
-	switch version {
+// newPacketKey parses data into a dense firewall.PacketKey. Hot path: no
+// netip.Addr construction, no unique.Handle interning. Caller decides
+// whether to also Hydrate to a Packet (for rule matching) or pass the key
+// straight to conntrack.
+func newPacketKey(data []byte, incoming bool) (firewall.PacketKey, error) {
+	var k firewall.PacketKey
+	if len(data) < 1 {
+		return k, ErrPacketTooShort
+	}
+	switch int((data[0] >> 4) & 0x0f) {
 	case ipv4.Version:
-		return parseV4(data, incoming, fp)
+		return k, parseV4Key(data, incoming, &k)
 	case ipv6.Version:
-		return parseV6(data, incoming, fp)
+		k.IsV6 = true
+		return k, parseV6Key(data, incoming, &k)
 	}
-	return ErrUnknownIPVersion
+	return k, ErrUnknownIPVersion
 }
 
-func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
+func parseV6Key(data []byte, incoming bool, k *firewall.PacketKey) 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])
+		copy(k.RemoteAddr[:], data[8:24])
+		copy(k.LocalAddr[:], data[24:40])
 	} else {
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[8:24])
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[24:40])
+		copy(k.LocalAddr[:], data[8:24])
+		copy(k.RemoteAddr[:], 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
+	protoAt := 6
+	offset := ipv6.HeaderLen
 	next := 0
 	for {
 		if protoAt >= dataLen {
@@ -353,87 +370,72 @@ func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
 
 		switch proto {
 		case layers.IPProtocolESP, layers.IPProtocolNoNextHeader:
-			fp.Protocol = uint8(proto)
-			fp.RemotePort = 0
-			fp.LocalPort = 0
-			fp.Fragment = false
+			k.Protocol = uint8(proto)
+			k.RemotePort = 0
+			k.LocalPort = 0
+			k.Fragment = false
 			return nil
 
 		case layers.IPProtocolICMPv6:
 			if dataLen < offset+6 {
 				return ErrIPv6PacketTooShort
 			}
-			fp.Protocol = uint8(proto)
-			fp.LocalPort = 0 //incoming vs outgoing doesn't matter for icmpv6
-			icmptype := data[offset+1]
-			switch icmptype {
+			k.Protocol = uint8(proto)
+			k.LocalPort = 0
+			switch data[offset+1] {
 			case layers.ICMPv6TypeEchoRequest, layers.ICMPv6TypeEchoReply:
-				fp.RemotePort = binary.BigEndian.Uint16(data[offset+4 : offset+6]) //identifier
+				k.RemotePort = binary.BigEndian.Uint16(data[offset+4 : offset+6])
 			default:
-				fp.RemotePort = 0
+				k.RemotePort = 0
 			}
-			fp.Fragment = false
+			k.Fragment = false
 			return nil
 
 		case layers.IPProtocolTCP, layers.IPProtocolUDP:
 			if dataLen < offset+4 {
 				return ErrIPv6PacketTooShort
 			}
-
-			fp.Protocol = uint8(proto)
+			k.Protocol = uint8(proto)
 			if incoming {
-				fp.RemotePort = binary.BigEndian.Uint16(data[offset : offset+2])
-				fp.LocalPort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
+				k.RemotePort = binary.BigEndian.Uint16(data[offset : offset+2])
+				k.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])
+				k.LocalPort = binary.BigEndian.Uint16(data[offset : offset+2])
+				k.RemotePort = binary.BigEndian.Uint16(data[offset+2 : offset+4])
 			}
-
-			fp.Fragment = false
+			k.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
+			fragmentOffset := binary.BigEndian.Uint16(data[offset+2:offset+4]) &^ uint16(0x7)
 			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
+				k.Protocol = data[offset]
+				k.Fragment = true
+				k.RemotePort = 0
+				k.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
+			next = 8
 
 		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
 	}
@@ -441,61 +443,54 @@ func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
 	return ErrIPv6CouldNotFindPayload
 }
 
-func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
-	// Do we at least have an ipv4 header worth of data?
+func parseV4Key(data []byte, incoming bool, k *firewall.PacketKey) error {
 	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
+	k.Fragment = (flagsfrags & 0x1FFF) != 0
+	k.Protocol = data[9]
 
-	// Firewall handles protocol checks
-	fp.Protocol = data[9]
-
-	// Accounting for a variable header length, do we have enough data for our src/dst tuples?
 	minLen := ihl
-	if !fp.Fragment {
-		if fp.Protocol == firewall.ProtoICMP {
+	if !k.Fragment {
+		if k.Protocol == firewall.ProtoICMP {
 			minLen += minFwPacketLen + 2
 		} else {
 			minLen += minFwPacketLen
 		}
 	}
-
 	if len(data) < minLen {
 		return ErrIPv4InvalidHeaderLength
 	}
 
-	if incoming { // Firewall packets are locally oriented
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[12:16])
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[16:20])
-	} else {
-		fp.LocalAddr, _ = netip.AddrFromSlice(data[12:16])
-		fp.RemoteAddr, _ = netip.AddrFromSlice(data[16:20])
-	}
-
-	if fp.Fragment {
-		fp.RemotePort = 0
-		fp.LocalPort = 0
-	} else if fp.Protocol == firewall.ProtoICMP { //note that orientation doesn't matter on ICMP
-		fp.RemotePort = binary.BigEndian.Uint16(data[ihl+4 : ihl+6]) //identifier
-		fp.LocalPort = 0                                             //code would be uint16(data[ihl+1])
-	} else if incoming {
-		fp.RemotePort = binary.BigEndian.Uint16(data[ihl : ihl+2])  //src port
-		fp.LocalPort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4]) //dst port
+	// Dense form: v4 in low 4 bytes, rest zero. Matches the coalescer's
+	// flowKey convention so the two stay byte-identical for the same flow.
+	if incoming {
+		copy(k.RemoteAddr[:4], data[12:16])
+		copy(k.LocalAddr[:4], data[16:20])
 	} else {
-		fp.LocalPort = binary.BigEndian.Uint16(data[ihl : ihl+2])    //src port
-		fp.RemotePort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4]) //dst port
+		copy(k.LocalAddr[:4], data[12:16])
+		copy(k.RemoteAddr[:4], data[16:20])
+	}
+
+	switch {
+	case k.Fragment:
+		k.RemotePort = 0
+		k.LocalPort = 0
+	case k.Protocol == firewall.ProtoICMP:
+		k.RemotePort = binary.BigEndian.Uint16(data[ihl+4 : ihl+6])
+		k.LocalPort = 0
+	case incoming:
+		k.RemotePort = binary.BigEndian.Uint16(data[ihl : ihl+2])
+		k.LocalPort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4])
+	default:
+		k.LocalPort = binary.BigEndian.Uint16(data[ihl : ihl+2])
+		k.RemotePort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4])
 	}
 
 	return nil

outside_test.go

@@ -529,7 +529,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("Normal", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(normalPacket, true, fp); err != nil {
+			if err = newPacket(normalPacket, true, fp); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -537,7 +537,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("FirstFragment", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(firstFrag, true, fp); err != nil {
+			if err = newPacket(firstFrag, true, fp); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -545,7 +545,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("SecondFragment", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(secondFrag, true, fp); err != nil {
+			if err = newPacket(secondFrag, true, fp); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -590,7 +590,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("200 HopByHop headers", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(evilBytes, false, fp); err != nil {
+			if err = newPacket(evilBytes, false, fp); err != nil {
 				b.Fatal(err)
 			}
 		}