TUN-8640: Refactor ICMPRouter to support new ICMPResponders

A new ICMPResponder interface is introduced to provide different
implementations of how the ICMP flows should return to the QUIC
connection muxer.

Improves usages of netip.AddrPort to leverage the embedded zone
field for IPv6 addresses.

Closes TUN-8640

cmd/cloudflared/tunnel/cmd.go

@@ -510,7 +510,7 @@ func StartServer(
 
 	// Disable ICMP packet routing for quick tunnels
 	if quickTunnelURL != "" {
-		tunnelConfig.PacketConfig = nil
+		tunnelConfig.ICMPRouterServer = nil
 	}
 
 	internalRules := []ingress.Rule{}

cmd/cloudflared/tunnel/configuration.go

@@ -252,11 +252,11 @@ func prepareTunnelConfig(
 		QUICConnectionLevelFlowControlLimit: c.Uint64(quicConnLevelFlowControlLimit),
 		QUICStreamLevelFlowControlLimit:     c.Uint64(quicStreamLevelFlowControlLimit),
 	}
-	packetConfig, err := newPacketConfig(c, log)
+	icmpRouter, err := newICMPRouter(c, log)
 	if err != nil {
 		log.Warn().Err(err).Msg("ICMP proxy feature is disabled")
 	} else {
-		tunnelConfig.PacketConfig = packetConfig
+		tunnelConfig.ICMPRouterServer = icmpRouter
 	}
 	orchestratorConfig := &orchestration.Config{
 		Ingress:            &ingressRules,
@@ -351,7 +351,7 @@ func adjustIPVersionByBindAddress(ipVersion allregions.ConfigIPVersion, ip net.I
 	}
 }
 
-func newPacketConfig(c *cli.Context, logger *zerolog.Logger) (*ingress.GlobalRouterConfig, error) {
+func newICMPRouter(c *cli.Context, logger *zerolog.Logger) (ingress.ICMPRouterServer, error) {
 	ipv4Src, err := determineICMPv4Src(c.String("icmpv4-src"), logger)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to determine IPv4 source address for ICMP proxy")
@@ -368,16 +368,11 @@ func newPacketConfig(c *cli.Context, logger *zerolog.Logger) (*ingress.GlobalRou
 		logger.Info().Msgf("ICMP proxy will use %s as source for IPv6", ipv6Src)
 	}
 
-	icmpRouter, err := ingress.NewICMPRouter(ipv4Src, ipv6Src, zone, logger, icmpFunnelTimeout)
+	icmpRouter, err := ingress.NewICMPRouter(ipv4Src, ipv6Src, logger, icmpFunnelTimeout)
 	if err != nil {
 		return nil, err
 	}
-	return &ingress.GlobalRouterConfig{
-		ICMPRouter: icmpRouter,
-		IPv4Src:    ipv4Src,
-		IPv6Src:    ipv6Src,
-		Zone:       zone,
-	}, nil
+	return icmpRouter, nil
 }
 
 func determineICMPv4Src(userDefinedSrc string, logger *zerolog.Logger) (netip.Addr, error) {
@@ -407,13 +402,12 @@ type interfaceIP struct {
 
 func determineICMPv6Src(userDefinedSrc string, logger *zerolog.Logger, ipv4Src netip.Addr) (addr netip.Addr, zone string, err error) {
 	if userDefinedSrc != "" {
-		userDefinedIP, zone, _ := strings.Cut(userDefinedSrc, "%")
-		addr, err := netip.ParseAddr(userDefinedIP)
+		addr, err := netip.ParseAddr(userDefinedSrc)
 		if err != nil {
 			return netip.Addr{}, "", err
 		}
 		if addr.Is6() {
-			return addr, zone, nil
+			return addr, addr.Zone(), nil
 		}
 		return netip.Addr{}, "", fmt.Errorf("expect IPv6, but %s is IPv4", userDefinedSrc)
 	}

connection/quic_connection.go

@@ -7,7 +7,6 @@ import (
 	"io"
 	"net"
 	"net/http"
-	"net/netip"
 	"strconv"
 	"strings"
 	"sync/atomic"
@@ -18,7 +17,6 @@ import (
 	"github.com/rs/zerolog"
 	"golang.org/x/sync/errgroup"
 
-	"github.com/cloudflare/cloudflared/packet"
 	cfdquic "github.com/cloudflare/cloudflared/quic"
 	"github.com/cloudflare/cloudflared/tracing"
 	"github.com/cloudflare/cloudflared/tunnelrpc/pogs"
@@ -417,28 +415,3 @@ func (np *nopCloserReadWriter) Close() error {
 
 	return nil
 }
-
-// muxerWrapper wraps DatagramMuxerV2 to satisfy the packet.FunnelUniPipe interface
-type muxerWrapper struct {
-	muxer *cfdquic.DatagramMuxerV2
-}
-
-func (rp *muxerWrapper) SendPacket(dst netip.Addr, pk packet.RawPacket) error {
-	return rp.muxer.SendPacket(cfdquic.RawPacket(pk))
-}
-
-func (rp *muxerWrapper) ReceivePacket(ctx context.Context) (packet.RawPacket, error) {
-	pk, err := rp.muxer.ReceivePacket(ctx)
-	if err != nil {
-		return packet.RawPacket{}, err
-	}
-	rawPacket, ok := pk.(cfdquic.RawPacket)
-	if ok {
-		return packet.RawPacket(rawPacket), nil
-	}
-	return packet.RawPacket{}, fmt.Errorf("unexpected packet type %+v", pk)
-}
-
-func (rp *muxerWrapper) Close() error {
-	return nil
-}

connection/quic_connection_test.go

@@ -752,7 +752,7 @@ func testTunnelConnection(t *testing.T, serverAddr netip.AddrPort, index uint8)
 	sessionDemuxChan := make(chan *packet.Session, 4)
 	datagramMuxer := cfdquic.NewDatagramMuxerV2(conn, &log, sessionDemuxChan)
 	sessionManager := datagramsession.NewManager(&log, datagramMuxer.SendToSession, sessionDemuxChan)
-	packetRouter := ingress.NewPacketRouter(nil, datagramMuxer, &log)
+	packetRouter := ingress.NewPacketRouter(nil, datagramMuxer, 0, &log)
 
 	datagramConn := &datagramV2Connection{
 		conn,

connection/quic_datagram_v2.go

@@ -54,15 +54,16 @@ type datagramV2Connection struct {
 
 func NewDatagramV2Connection(ctx context.Context,
 	conn quic.Connection,
-	packetConfig *ingress.GlobalRouterConfig,
+	icmpRouter ingress.ICMPRouter,
+	index uint8,
 	rpcTimeout time.Duration,
 	streamWriteTimeout time.Duration,
 	logger *zerolog.Logger,
 ) DatagramSessionHandler {
 	sessionDemuxChan := make(chan *packet.Session, demuxChanCapacity)
 	datagramMuxer := cfdquic.NewDatagramMuxerV2(conn, logger, sessionDemuxChan)
 	sessionManager := datagramsession.NewManager(logger, datagramMuxer.SendToSession, sessionDemuxChan)
-	packetRouter := ingress.NewPacketRouter(packetConfig, datagramMuxer, logger)
+	packetRouter := ingress.NewPacketRouter(icmpRouter, datagramMuxer, index, logger)
 
 	return &datagramV2Connection{
 		conn,

ingress/icmp_darwin.go

@@ -28,10 +28,8 @@ type icmpProxy struct {
 	srcFunnelTracker *packet.FunnelTracker
 	echoIDTracker    *echoIDTracker
 	conn             *icmp.PacketConn
-	// Response is handled in one-by-one, so encoder can be shared between funnels
-	encoder     *packet.Encoder
-	logger      *zerolog.Logger
-	idleTimeout time.Duration
+	logger           *zerolog.Logger
+	idleTimeout      time.Duration
 }
 
 // echoIDTracker tracks which ID has been assigned. It first loops through assignment from lastAssignment to then end,
@@ -114,25 +112,24 @@ func (snf echoFunnelID) String() string {
 	return strconv.FormatUint(uint64(snf), 10)
 }
 
-func newICMPProxy(listenIP netip.Addr, zone string, logger *zerolog.Logger, idleTimeout time.Duration) (*icmpProxy, error) {
-	conn, err := newICMPConn(listenIP, zone)
+func newICMPProxy(listenIP netip.Addr, logger *zerolog.Logger, idleTimeout time.Duration) (*icmpProxy, error) {
+	conn, err := newICMPConn(listenIP)
 	if err != nil {
 		return nil, err
 	}
 	logger.Info().Msgf("Created ICMP proxy listening on %s", conn.LocalAddr())
 	return &icmpProxy{
 		srcFunnelTracker: packet.NewFunnelTracker(),
 		echoIDTracker:    newEchoIDTracker(),
-		encoder:          packet.NewEncoder(),
 		conn:             conn,
 		logger:           logger,
 		idleTimeout:      idleTimeout,
 	}, nil
 }
 
-func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *packetResponder) error {
-	_, span := responder.requestSpan(ctx, pk)
-	defer responder.exportSpan()
+func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder ICMPResponder) error {
+	_, span := responder.RequestSpan(ctx, pk)
+	defer responder.ExportSpan()
 
 	originalEcho, err := getICMPEcho(pk.Message)
 	if err != nil {
@@ -154,7 +151,7 @@ func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *pa
 	}
 	span.SetAttributes(attribute.Int("assignedEchoID", int(assignedEchoID)))
 
-	shouldReplaceFunnelFunc := createShouldReplaceFunnelFunc(ip.logger, responder.datagramMuxer, pk, originalEcho.ID)
+	shouldReplaceFunnelFunc := createShouldReplaceFunnelFunc(ip.logger, responder, pk, originalEcho.ID)
 	newFunnelFunc := func() (packet.Funnel, error) {
 		originalEcho, err := getICMPEcho(pk.Message)
 		if err != nil {
@@ -164,7 +161,7 @@ func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *pa
 			ip.echoIDTracker.release(echoIDTrackerKey, assignedEchoID)
 			return nil
 		}
-		icmpFlow := newICMPEchoFlow(pk.Src, closeCallback, ip.conn, responder, int(assignedEchoID), originalEcho.ID, ip.encoder)
+		icmpFlow := newICMPEchoFlow(pk.Src, closeCallback, ip.conn, responder, int(assignedEchoID), originalEcho.ID)
 		return icmpFlow, nil
 	}
 	funnelID := echoFunnelID(assignedEchoID)
@@ -265,8 +262,8 @@ func (ip *icmpProxy) sendReply(ctx context.Context, reply *echoReply) error {
 		return err
 	}
 
-	_, span := icmpFlow.responder.replySpan(ctx, ip.logger)
-	defer icmpFlow.responder.exportSpan()
+	_, span := icmpFlow.responder.ReplySpan(ctx, ip.logger)
+	defer icmpFlow.responder.ExportSpan()
 
 	if err := icmpFlow.returnToSrc(reply); err != nil {
 		tracing.EndWithErrorStatus(span, err)

ingress/icmp_generic.go

@@ -18,14 +18,14 @@ var errICMPProxyNotImplemented = fmt.Errorf("ICMP proxy is not implemented on %s
 
 type icmpProxy struct{}
 
-func (ip icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *packetResponder) error {
+func (ip icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder ICMPResponder) error {
 	return errICMPProxyNotImplemented
 }
 
 func (ip *icmpProxy) Serve(ctx context.Context) error {
 	return errICMPProxyNotImplemented
 }
 
-func newICMPProxy(listenIP netip.Addr, zone string, logger *zerolog.Logger, idleTimeout time.Duration) (*icmpProxy, error) {
+func newICMPProxy(listenIP netip.Addr, logger *zerolog.Logger, idleTimeout time.Duration) (*icmpProxy, error) {
 	return nil, errICMPProxyNotImplemented
 }

ingress/icmp_linux.go

@@ -37,25 +37,23 @@ var (
 type icmpProxy struct {
 	srcFunnelTracker *packet.FunnelTracker
 	listenIP         netip.Addr
-	ipv6Zone         string
 	logger           *zerolog.Logger
 	idleTimeout      time.Duration
 }
 
-func newICMPProxy(listenIP netip.Addr, zone string, logger *zerolog.Logger, idleTimeout time.Duration) (*icmpProxy, error) {
-	if err := testPermission(listenIP, zone, logger); err != nil {
+func newICMPProxy(listenIP netip.Addr, logger *zerolog.Logger, idleTimeout time.Duration) (*icmpProxy, error) {
+	if err := testPermission(listenIP, logger); err != nil {
 		return nil, err
 	}
 	return &icmpProxy{
 		srcFunnelTracker: packet.NewFunnelTracker(),
 		listenIP:         listenIP,
-		ipv6Zone:         zone,
 		logger:           logger,
 		idleTimeout:      idleTimeout,
 	}, nil
 }
 
-func testPermission(listenIP netip.Addr, zone string, logger *zerolog.Logger) error {
+func testPermission(listenIP netip.Addr, logger *zerolog.Logger) error {
 	// Opens a non-privileged ICMP socket. On Linux the group ID of the process needs to be in ping_group_range
 	// Only check ping_group_range once for IPv4
 	if listenIP.Is4() {
@@ -64,7 +62,7 @@ func testPermission(listenIP netip.Addr, zone string, logger *zerolog.Logger) er
 			return err
 		}
 	}
-	conn, err := newICMPConn(listenIP, zone)
+	conn, err := newICMPConn(listenIP)
 	if err != nil {
 		return err
 	}
@@ -98,9 +96,9 @@ func checkInPingGroup() error {
 	return fmt.Errorf("did not find group range in %s", pingGroupPath)
 }
 
-func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *packetResponder) error {
-	ctx, span := responder.requestSpan(ctx, pk)
-	defer responder.exportSpan()
+func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder ICMPResponder) error {
+	ctx, span := responder.RequestSpan(ctx, pk)
+	defer responder.ExportSpan()
 
 	originalEcho, err := getICMPEcho(pk.Message)
 	if err != nil {
@@ -109,9 +107,9 @@ func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *pa
 	}
 	observeICMPRequest(ip.logger, span, pk.Src.String(), pk.Dst.String(), originalEcho.ID, originalEcho.Seq)
 
-	shouldReplaceFunnelFunc := createShouldReplaceFunnelFunc(ip.logger, responder.datagramMuxer, pk, originalEcho.ID)
+	shouldReplaceFunnelFunc := createShouldReplaceFunnelFunc(ip.logger, responder, pk, originalEcho.ID)
 	newFunnelFunc := func() (packet.Funnel, error) {
-		conn, err := newICMPConn(ip.listenIP, ip.ipv6Zone)
+		conn, err := newICMPConn(ip.listenIP)
 		if err != nil {
 			tracing.EndWithErrorStatus(span, err)
 			return nil, errors.Wrap(err, "failed to open ICMP socket")
@@ -127,7 +125,7 @@ func (ip *icmpProxy) Request(ctx context.Context, pk *packet.ICMP, responder *pa
 		span.SetAttributes(attribute.Int("port", localUDPAddr.Port))
 
 		echoID := localUDPAddr.Port
-		icmpFlow := newICMPEchoFlow(pk.Src, closeCallback, conn, responder, echoID, originalEcho.ID, packet.NewEncoder())
+		icmpFlow := newICMPEchoFlow(pk.Src, closeCallback, conn, responder, echoID, originalEcho.ID)
 		return icmpFlow, nil
 	}
 	funnelID := flow3Tuple{
@@ -181,8 +179,8 @@ func (ip *icmpProxy) listenResponse(ctx context.Context, flow *icmpEchoFlow) {
 
 // Listens for ICMP response and handles error logging
 func (ip *icmpProxy) handleResponse(ctx context.Context, flow *icmpEchoFlow, buf []byte) (done bool) {
-	_, span := flow.responder.replySpan(ctx, ip.logger)
-	defer flow.responder.exportSpan()
+	_, span := flow.responder.ReplySpan(ctx, ip.logger)
+	defer flow.responder.ExportSpan()
 
 	span.SetAttributes(
 		attribute.Int("originalEchoID", flow.originalEchoID),

ingress/icmp_posix.go

@@ -18,23 +18,20 @@ import (
 )
 
 // Opens a non-privileged ICMP socket on Linux and Darwin
-func newICMPConn(listenIP netip.Addr, zone string) (*icmp.PacketConn, error) {
+func newICMPConn(listenIP netip.Addr) (*icmp.PacketConn, error) {
 	if listenIP.Is4() {
 		return icmp.ListenPacket("udp4", listenIP.String())
 	}
-	listenAddr := listenIP.String()
-	if zone != "" {
-		listenAddr = listenAddr + "%" + zone
-	}
-	return icmp.ListenPacket("udp6", listenAddr)
+	return icmp.ListenPacket("udp6", listenIP.String())
 }
 
 func netipAddr(addr net.Addr) (netip.Addr, bool) {
 	udpAddr, ok := addr.(*net.UDPAddr)
 	if !ok {
 		return netip.Addr{}, false
 	}
-	return netip.AddrFromSlice(udpAddr.IP)
+
+	return udpAddr.AddrPort().Addr(), true
 }
 
 type flow3Tuple struct {
@@ -50,14 +47,12 @@ type icmpEchoFlow struct {
 	closed         *atomic.Bool
 	src            netip.Addr
 	originConn     *icmp.PacketConn
-	responder      *packetResponder
+	responder      ICMPResponder
 	assignedEchoID int
 	originalEchoID int
-	// it's up to the user to ensure respEncoder is not used concurrently
-	respEncoder *packet.Encoder
 }
 
-func newICMPEchoFlow(src netip.Addr, closeCallback func() error, originConn *icmp.PacketConn, responder *packetResponder, assignedEchoID, originalEchoID int, respEncoder *packet.Encoder) *icmpEchoFlow {
+func newICMPEchoFlow(src netip.Addr, closeCallback func() error, originConn *icmp.PacketConn, responder ICMPResponder, assignedEchoID, originalEchoID int) *icmpEchoFlow {
 	return &icmpEchoFlow{
 		ActivityTracker: packet.NewActivityTracker(),
 		closeCallback:   closeCallback,
@@ -67,7 +62,6 @@ func newICMPEchoFlow(src netip.Addr, closeCallback func() error, originConn *icm
 		responder:       responder,
 		assignedEchoID:  assignedEchoID,
 		originalEchoID:  originalEchoID,
-		respEncoder:     respEncoder,
 	}
 }
 
@@ -139,11 +133,7 @@ func (ief *icmpEchoFlow) returnToSrc(reply *echoReply) error {
 		},
 		Message: reply.msg,
 	}
-	serializedPacket, err := ief.respEncoder.Encode(&pk)
-	if err != nil {
-		return err
-	}
-	return ief.responder.returnPacket(serializedPacket)
+	return ief.responder.ReturnPacket(&pk)
 }
 
 type echoReply struct {
@@ -184,7 +174,7 @@ func toICMPEchoFlow(funnel packet.Funnel) (*icmpEchoFlow, error) {
 	return icmpFlow, nil
 }
 
-func createShouldReplaceFunnelFunc(logger *zerolog.Logger, muxer muxer, pk *packet.ICMP, originalEchoID int) func(packet.Funnel) bool {
+func createShouldReplaceFunnelFunc(logger *zerolog.Logger, responder ICMPResponder, pk *packet.ICMP, originalEchoID int) func(packet.Funnel) bool {
 	return func(existing packet.Funnel) bool {
 		existingFlow, err := toICMPEchoFlow(existing)
 		if err != nil {
@@ -199,7 +189,7 @@ func createShouldReplaceFunnelFunc(logger *zerolog.Logger, muxer muxer, pk *pack
 		// If the existing flow has a different muxer, there's a new quic connection where return packets should be
 		// routed. Otherwise, return packets will be send to the first observed incoming connection, rather than the
 		// most recently observed connection.
-		if existingFlow.responder.datagramMuxer != muxer {
+		if existingFlow.responder.ConnectionIndex() != responder.ConnectionIndex() {
 			logger.Debug().
 				Str("src", pk.Src.String()).
 				Str("dst", pk.Dst.String()).