Add ICMP stats

PiperOrigin-RevId: 240848882
Change-Id: I23dd4599f073263437aeab357c3f767e1a432b82

4 files changed, 294 insertions, 75 deletions

diff --git a/pkg/tcpip/network/ip_test.go b/pkg/tcpip/network/ip_test.go
index d79eba4b0..522009fac 100644
--- a/pkg/tcpip/network/ip_test.go
+++ b/pkg/tcpip/network/ip_test.go
@@ -287,9 +287,9 @@ func TestIPv4ReceiveControl(t *testing.T) {
 		{"Non-zero fragment offset", 0, 100, header.ICMPv4PortUnreachable, stack.ControlPortUnreachable, 0, 0},
 		{"Zero-length packet", 0, 0, header.ICMPv4PortUnreachable, stack.ControlPortUnreachable, 0, 2*header.IPv4MinimumSize + header.ICMPv4DstUnreachableMinimumSize + 8},
 	}
-	r := stack.Route{
-		LocalAddress:  localIpv4Addr,
-		RemoteAddress: "\x0a\x00\x00\xbb",
+	r, err := buildIPv4Route(localIpv4Addr, "\x0a\x00\x00\xbb")
+	if err != nil {
+		t.Fatal(err)
 	}
 	for _, c := range cases {
 		t.Run(c.name, func(t *testing.T) {
@@ -521,9 +521,12 @@ func TestIPv6ReceiveControl(t *testing.T) {
 		{"Non-zero fragment offset", 0, newUint16(100), header.ICMPv6DstUnreachable, header.ICMPv6PortUnreachable, stack.ControlPortUnreachable, 0, 0},
 		{"Zero-length packet", 0, nil, header.ICMPv6DstUnreachable, header.ICMPv6PortUnreachable, stack.ControlPortUnreachable, 0, 2*header.IPv6MinimumSize + header.ICMPv6DstUnreachableMinimumSize + 8},
 	}
-	r := stack.Route{
-		LocalAddress:  localIpv6Addr,
-		RemoteAddress: "\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xaa",
+	r, err := buildIPv6Route(
+		localIpv6Addr,
+		"\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xaa",
+	)
+	if err != nil {
+		t.Fatal(err)
 	}
 	for _, c := range cases {
 		t.Run(c.name, func(t *testing.T) {
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index a9650de03..ed9a4eee5 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -55,15 +55,21 @@ func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, vv buffer.
 }
 
 func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.VectorisedView) {
+	stats := r.Stats()
+	received := stats.ICMP.V4PacketsReceived
 	v := vv.First()
 	if len(v) < header.ICMPv4MinimumSize {
+		received.Invalid.Increment()
 		return
 	}
 	h := header.ICMPv4(v)
 
+	// TODO: Meaningfully handle all ICMP types.
 	switch h.Type() {
 	case header.ICMPv4Echo:
+		received.Echo.Increment()
 		if len(v) < header.ICMPv4EchoMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 		// It's possible that a raw socket expects to receive this.
@@ -76,16 +82,25 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		copy(pkt, h)
 		pkt.SetType(header.ICMPv4EchoReply)
 		pkt.SetChecksum(^header.Checksum(pkt, header.ChecksumVV(vv, 0)))
-		r.WritePacket(nil /* gso */, hdr, vv, header.ICMPv4ProtocolNumber, r.DefaultTTL())
+		sent := stats.ICMP.V4PacketsSent
+		if err := r.WritePacket(nil /* gso */, hdr, vv, header.ICMPv4ProtocolNumber, r.DefaultTTL()); err != nil {
+			sent.Dropped.Increment()
+			return
+		}
+		sent.EchoReply.Increment()
 
 	case header.ICMPv4EchoReply:
+		received.EchoReply.Increment()
 		if len(v) < header.ICMPv4EchoMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 		e.dispatcher.DeliverTransportPacket(r, header.ICMPv4ProtocolNumber, netHeader, vv)
 
 	case header.ICMPv4DstUnreachable:
+		received.DstUnreachable.Increment()
 		if len(v) < header.ICMPv4DstUnreachableMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 		vv.TrimFront(header.ICMPv4DstUnreachableMinimumSize)
@@ -97,6 +112,32 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 			mtu := uint32(binary.BigEndian.Uint16(v[header.ICMPv4DstUnreachableMinimumSize-2:]))
 			e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), vv)
 		}
+
+	case header.ICMPv4SrcQuench:
+		received.SrcQuench.Increment()
+
+	case header.ICMPv4Redirect:
+		received.Redirect.Increment()
+
+	case header.ICMPv4TimeExceeded:
+		received.TimeExceeded.Increment()
+
+	case header.ICMPv4ParamProblem:
+		received.ParamProblem.Increment()
+
+	case header.ICMPv4Timestamp:
+		received.Timestamp.Increment()
+
+	case header.ICMPv4TimestampReply:
+		received.TimestampReply.Increment()
+
+	case header.ICMPv4InfoRequest:
+		received.InfoRequest.Increment()
+
+	case header.ICMPv4InfoReply:
+		received.InfoReply.Increment()
+
+	default:
+		received.Invalid.Increment()
 	}
-	// TODO: Handle other ICMP types.
 }
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index 36d98caef..3210e6fc7 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -63,15 +63,22 @@ func (e *endpoint) handleControl(typ stack.ControlType, extra uint32, vv buffer.
 }
 
 func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.VectorisedView) {
+	stats := r.Stats().ICMP
+	sent := stats.V6PacketsSent
+	received := stats.V6PacketsReceived
 	v := vv.First()
 	if len(v) < header.ICMPv6MinimumSize {
+		received.Invalid.Increment()
 		return
 	}
 	h := header.ICMPv6(v)
 
+	// TODO: Meaningfully handle all ICMP types.
 	switch h.Type() {
 	case header.ICMPv6PacketTooBig:
+		received.PacketTooBig.Increment()
 		if len(v) < header.ICMPv6PacketTooBigMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 		vv.TrimFront(header.ICMPv6PacketTooBigMinimumSize)
@@ -79,7 +86,9 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), vv)
 
 	case header.ICMPv6DstUnreachable:
+		received.DstUnreachable.Increment()
 		if len(v) < header.ICMPv6DstUnreachableMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 		vv.TrimFront(header.ICMPv6DstUnreachableMinimumSize)
@@ -89,15 +98,21 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		}
 
 	case header.ICMPv6NeighborSolicit:
+		received.NeighborSolicit.Increment()
+
+		e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress)
+
 		if len(v) < header.ICMPv6NeighborSolicitMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
-		targetAddr := tcpip.Address(v[8 : 8+16])
+		targetAddr := tcpip.Address(v[8:][:16])
 		if e.linkAddrCache.CheckLocalAddress(e.nicid, ProtocolNumber, targetAddr) == 0 {
 			// We don't have a useful answer; the best we can do is ignore the request.
 			return
 		}
-		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6NeighborAdvertSize)
+
+		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6NeighborAdvertSize)
 		pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertSize))
 		pkt.SetType(header.ICMPv6NeighborAdvert)
 		pkt[icmpV6FlagOffset] = ndpSolicitedFlag | ndpOverrideFlag
@@ -118,22 +133,29 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		defer r.Release()
 		r.LocalAddress = targetAddr
 		pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
-		r.WritePacket(nil /* gso */, hdr, buffer.VectorisedView{}, header.ICMPv6ProtocolNumber, r.DefaultTTL())
 
-		e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress)
+		if err := r.WritePacket(nil /* gso */, hdr, buffer.VectorisedView{}, header.ICMPv6ProtocolNumber, r.DefaultTTL()); err != nil {
+			sent.Dropped.Increment()
+			return
+		}
+		sent.NeighborAdvert.Increment()
 
 	case header.ICMPv6NeighborAdvert:
+		received.NeighborAdvert.Increment()
 		if len(v) < header.ICMPv6NeighborAdvertSize {
+			received.Invalid.Increment()
 			return
 		}
-		targetAddr := tcpip.Address(v[8 : 8+16])
+		targetAddr := tcpip.Address(v[8:][:16])
 		e.linkAddrCache.AddLinkAddress(e.nicid, targetAddr, r.RemoteLinkAddress)
 		if targetAddr != r.RemoteAddress {
 			e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress)
 		}
 
 	case header.ICMPv6EchoRequest:
+		received.EchoRequest.Increment()
 		if len(v) < header.ICMPv6EchoMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 
@@ -143,14 +165,37 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		copy(pkt, h)
 		pkt.SetType(header.ICMPv6EchoReply)
 		pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, vv))
-		r.WritePacket(nil /* gso */, hdr, vv, header.ICMPv6ProtocolNumber, r.DefaultTTL())
+		if err := r.WritePacket(nil /* gso */, hdr, vv, header.ICMPv6ProtocolNumber, r.DefaultTTL()); err != nil {
+			sent.Dropped.Increment()
+			return
+		}
+		sent.EchoReply.Increment()
 
 	case header.ICMPv6EchoReply:
+		received.EchoReply.Increment()
 		if len(v) < header.ICMPv6EchoMinimumSize {
+			received.Invalid.Increment()
 			return
 		}
 		e.dispatcher.DeliverTransportPacket(r, header.ICMPv6ProtocolNumber, netHeader, vv)
 
+	case header.ICMPv6TimeExceeded:
+		received.TimeExceeded.Increment()
+
+	case header.ICMPv6ParamProblem:
+		received.ParamProblem.Increment()
+
+	case header.ICMPv6RouterSolicit:
+		received.RouterSolicit.Increment()
+
+	case header.ICMPv6RouterAdvert:
+		received.RouterAdvert.Increment()
+
+	case header.ICMPv6RedirectMsg:
+		received.RedirectMsg.Increment()
+
+	default:
+		received.Invalid.Increment()
 	}
 }
 
@@ -202,6 +247,7 @@ func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack.
 		DstAddr:       r.RemoteAddress,
 	})
 
+	// TODO: count this in ICMP stats.
 	return linkEP.WritePacket(r, nil /* gso */, hdr, buffer.VectorisedView{}, ProtocolNumber)
 }
 
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index eee09f3af..8b57a0641 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -15,9 +15,10 @@
 package ipv6
 
 import (
+	"fmt"
+	"reflect"
 	"strings"
 	"testing"
-	"time"
 
 	"gvisor.googlesource.com/gvisor/pkg/tcpip"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
@@ -39,20 +40,151 @@ var (
 	lladdr1 = header.LinkLocalAddr(linkAddr1)
 )
 
-type icmpInfo struct {
-	typ header.ICMPv6Type
-	src tcpip.Address
+type stubLinkEndpoint struct {
+	stack.LinkEndpoint
+}
+
+func (*stubLinkEndpoint) Capabilities() stack.LinkEndpointCapabilities {
+	return 0
+}
+
+func (*stubLinkEndpoint) MaxHeaderLength() uint16 {
+	return 0
+}
+
+func (*stubLinkEndpoint) LinkAddress() tcpip.LinkAddress {
+	return ""
+}
+
+func (*stubLinkEndpoint) WritePacket(*stack.Route, *stack.GSO, buffer.Prependable, buffer.VectorisedView, tcpip.NetworkProtocolNumber) *tcpip.Error {
+	return nil
+}
+
+func (*stubLinkEndpoint) Attach(stack.NetworkDispatcher) {}
+
+type stubDispatcher struct {
+	stack.TransportDispatcher
+}
+
+func (*stubDispatcher) DeliverTransportPacket(*stack.Route, tcpip.TransportProtocolNumber, buffer.View, buffer.VectorisedView) {
+}
+
+type stubLinkAddressCache struct {
+	stack.LinkAddressCache
+}
+
+func (*stubLinkAddressCache) CheckLocalAddress(tcpip.NICID, tcpip.NetworkProtocolNumber, tcpip.Address) tcpip.NICID {
+	return 0
+}
+
+func (*stubLinkAddressCache) AddLinkAddress(tcpip.NICID, tcpip.Address, tcpip.LinkAddress) {
+}
+
+func TestICMPCounts(t *testing.T) {
+	s := stack.New([]string{ProtocolName}, []string{icmp.ProtocolName6}, stack.Options{})
+	{
+		id := stack.RegisterLinkEndpoint(&stubLinkEndpoint{})
+		if err := s.CreateNIC(1, id); err != nil {
+			t.Fatalf("CreateNIC(_) = %s", err)
+		}
+		if err := s.AddAddress(1, ProtocolNumber, lladdr0); err != nil {
+			t.Fatalf("AddAddress(_, %d, %s) = %s", ProtocolNumber, lladdr0, err)
+		}
+	}
+	s.SetRouteTable(
+		[]tcpip.Route{{
+			Destination: lladdr1,
+			Mask:        tcpip.AddressMask(strings.Repeat("\xff", 16)),
+			NIC:         1,
+		}},
+	)
+
+	ep, err := s.NetworkProtocolInstance(ProtocolNumber).NewEndpoint(0, lladdr1, &stubLinkAddressCache{}, &stubDispatcher{}, nil)
+	if err != nil {
+		t.Fatalf("NewEndpoint(_) = _, %s, want = _, nil", err)
+	}
+
+	r, err := s.FindRoute(1, lladdr0, lladdr1, ProtocolNumber, false /* multicastLoop */)
+	if err != nil {
+		t.Fatalf("FindRoute(_) = _, %s, want = _, nil", err)
+	}
+	defer r.Release()
+
+	types := []struct {
+		typ  header.ICMPv6Type
+		size int
+	}{
+		{header.ICMPv6DstUnreachable, header.ICMPv6DstUnreachableMinimumSize},
+		{header.ICMPv6PacketTooBig, header.ICMPv6PacketTooBigMinimumSize},
+		{header.ICMPv6TimeExceeded, header.ICMPv6MinimumSize},
+		{header.ICMPv6ParamProblem, header.ICMPv6MinimumSize},
+		{header.ICMPv6EchoRequest, header.ICMPv6EchoMinimumSize},
+		{header.ICMPv6EchoReply, header.ICMPv6EchoMinimumSize},
+		{header.ICMPv6RouterSolicit, header.ICMPv6MinimumSize},
+		{header.ICMPv6RouterAdvert, header.ICMPv6MinimumSize},
+		{header.ICMPv6NeighborSolicit, header.ICMPv6NeighborSolicitMinimumSize},
+		{header.ICMPv6NeighborAdvert, header.ICMPv6NeighborAdvertSize},
+		{header.ICMPv6RedirectMsg, header.ICMPv6MinimumSize},
+	}
+
+	handleIPv6Payload := func(hdr buffer.Prependable) {
+		payloadLength := hdr.UsedLength()
+		ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
+		ip.Encode(&header.IPv6Fields{
+			PayloadLength: uint16(payloadLength),
+			NextHeader:    uint8(header.ICMPv6ProtocolNumber),
+			HopLimit:      r.DefaultTTL(),
+			SrcAddr:       r.LocalAddress,
+			DstAddr:       r.RemoteAddress,
+		})
+		ep.HandlePacket(&r, hdr.View().ToVectorisedView())
+	}
+
+	for _, typ := range types {
+		hdr := buffer.NewPrependable(header.IPv6MinimumSize + typ.size)
+		pkt := header.ICMPv6(hdr.Prepend(typ.size))
+		pkt.SetType(typ.typ)
+		pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+
+		handleIPv6Payload(hdr)
+	}
+
+	// Construct an empty ICMP packet so that
+	// Stats().ICMP.ICMPv6ReceivedPacketStats.Invalid is incremented.
+	handleIPv6Payload(buffer.NewPrependable(header.IPv6MinimumSize))
+
+	icmpv6Stats := s.Stats().ICMP.V6PacketsReceived
+	visitStats(reflect.ValueOf(&icmpv6Stats).Elem(), func(name string, s *tcpip.StatCounter) {
+		if got, want := s.Value(), uint64(1); got != want {
+			t.Errorf("got %s = %d, want = %d", name, got, want)
+		}
+	})
+	if t.Failed() {
+		t.Logf("stats:\n%+v", s.Stats())
+	}
+}
+
+func visitStats(v reflect.Value, f func(string, *tcpip.StatCounter)) {
+	t := v.Type()
+	for i := 0; i < v.NumField(); i++ {
+		v := v.Field(i)
+		switch v.Kind() {
+		case reflect.Ptr:
+			f(t.Field(i).Name, v.Interface().(*tcpip.StatCounter))
+		case reflect.Struct:
+			visitStats(v, f)
+		default:
+			panic(fmt.Sprintf("unexpected type %s", v.Type()))
+		}
+	}
 }
 
 type testContext struct {
-	t  *testing.T
 	s0 *stack.Stack
 	s1 *stack.Stack
 
 	linkEP0 *channel.Endpoint
 	linkEP1 *channel.Endpoint
-
-	icmpCh chan icmpInfo
 }
 
 type endpointWithResolutionCapability struct {
@@ -65,10 +197,8 @@ func (e endpointWithResolutionCapability) Capabilities() stack.LinkEndpointCapab
 
 func newTestContext(t *testing.T) *testContext {
 	c := &testContext{
-		t:      t,
-		s0:     stack.New([]string{ProtocolName}, []string{icmp.ProtocolName6}, stack.Options{}),
-		s1:     stack.New([]string{ProtocolName}, []string{icmp.ProtocolName6}, stack.Options{}),
-		icmpCh: make(chan icmpInfo, 10),
+		s0: stack.New([]string{ProtocolName}, []string{icmp.ProtocolName6}, stack.Options{}),
+		s1: stack.New([]string{ProtocolName}, []string{icmp.ProtocolName6}, stack.Options{}),
 	}
 
 	const defaultMTU = 65536
@@ -118,50 +248,58 @@ func newTestContext(t *testing.T) *testContext {
 		}},
 	)
 
-	go c.routePackets(linkEP0.C, linkEP1)
-	go c.routePackets(linkEP1.C, linkEP0)
-
 	return c
 }
 
-func (c *testContext) countPacket(pkt channel.PacketInfo) {
+func (c *testContext) cleanup() {
+	close(c.linkEP0.C)
+	close(c.linkEP1.C)
+}
+
+type routeArgs struct {
+	src, dst *channel.Endpoint
+	typ      header.ICMPv6Type
+}
+
+func routeICMPv6Packet(t *testing.T, args routeArgs, fn func(*testing.T, header.ICMPv6)) {
+	t.Helper()
+
+	pkt := <-args.src.C
+
+	{
+		views := []buffer.View{pkt.Header, pkt.Payload}
+		size := len(pkt.Header) + len(pkt.Payload)
+		vv := buffer.NewVectorisedView(size, views)
+		args.dst.InjectLinkAddr(pkt.Proto, args.dst.LinkAddress(), vv)
+	}
+
 	if pkt.Proto != ProtocolNumber {
+		t.Errorf("unexpected protocol number %d", pkt.Proto)
 		return
 	}
 	ipv6 := header.IPv6(pkt.Header)
 	transProto := tcpip.TransportProtocolNumber(ipv6.NextHeader())
 	if transProto != header.ICMPv6ProtocolNumber {
+		t.Errorf("unexpected transport protocol number %d", transProto)
 		return
 	}
-	b := pkt.Header[header.IPv6MinimumSize:]
-	icmp := header.ICMPv6(b)
-	c.icmpCh <- icmpInfo{
-		typ: icmp.Type(),
-		src: ipv6.SourceAddress(),
+	icmpv6 := header.ICMPv6(ipv6.Payload())
+	if got, want := icmpv6.Type(), args.typ; got != want {
+		t.Errorf("got ICMPv6 type = %d, want = %d", got, want)
+		return
 	}
-}
-
-func (c *testContext) routePackets(ch <-chan channel.PacketInfo, ep *channel.Endpoint) {
-	for pkt := range ch {
-		c.countPacket(pkt)
-		views := []buffer.View{pkt.Header, pkt.Payload}
-		size := len(pkt.Header) + len(pkt.Payload)
-		vv := buffer.NewVectorisedView(size, views)
-		ep.InjectLinkAddr(pkt.Proto, ep.LinkAddress(), vv)
+	if fn != nil {
+		fn(t, icmpv6)
 	}
 }
 
-func (c *testContext) cleanup() {
-	close(c.linkEP0.C)
-	close(c.linkEP1.C)
-}
-
 func TestLinkResolution(t *testing.T) {
 	c := newTestContext(t)
 	defer c.cleanup()
+
 	r, err := c.s0.FindRoute(1, lladdr0, lladdr1, ProtocolNumber, false /* multicastLoop */)
 	if err != nil {
-		t.Fatal(err)
+		t.Fatalf("FindRoute(_) = _, %s, want = _, nil", err)
 	}
 	defer r.Release()
 
@@ -176,14 +314,24 @@ func TestLinkResolution(t *testing.T) {
 	var wq waiter.Queue
 	ep, err := c.s0.NewEndpoint(header.ICMPv6ProtocolNumber, ProtocolNumber, &wq)
 	if err != nil {
-		t.Fatal(err)
+		t.Fatalf("NewEndpoint(_) = _, %s, want = _, nil", err)
 	}
 
 	for {
 		_, resCh, err := ep.Write(payload, tcpip.WriteOptions{To: &tcpip.FullAddress{NIC: 1, Addr: lladdr1}})
 		if resCh != nil {
 			if err != tcpip.ErrNoLinkAddress {
-				t.Fatalf("ep.Write(_) = _, <non-nil>, %s want _, <non-nil>, tcpip.ErrNoLinkAddress", err)
+				t.Fatalf("ep.Write(_) = _, <non-nil>, %s, want = _, <non-nil>, tcpip.ErrNoLinkAddress", err)
+			}
+			for _, args := range []routeArgs{
+				{src: c.linkEP0, dst: c.linkEP1, typ: header.ICMPv6NeighborSolicit},
+				{src: c.linkEP1, dst: c.linkEP0, typ: header.ICMPv6NeighborAdvert},
+			} {
+				routeICMPv6Packet(t, args, func(t *testing.T, icmpv6 header.ICMPv6) {
+					if got, want := tcpip.Address(icmpv6[8:][:16]), lladdr1; got != want {
+						t.Errorf("%d: got target = %s, want = %s", icmpv6.Type(), got, want)
+					}
+				})
 			}
 			<-resCh
 			continue
@@ -194,29 +342,10 @@ func TestLinkResolution(t *testing.T) {
 		break
 	}
 
-	stats := make(map[header.ICMPv6Type]int)
-	for {
-		// This actually takes about 10 milliseconds, so no need to wait for
-		// a multi-minute go test timeout if something is broken.
-		select {
-		case <-time.After(2 * time.Second):
-			t.Errorf("timeout waiting for ICMP, got: %#+v", stats)
-			return
-		case icmpInfo := <-c.icmpCh:
-			switch icmpInfo.typ {
-			case header.ICMPv6NeighborAdvert:
-				if got, want := icmpInfo.src, lladdr1; got != want {
-					t.Errorf("got ICMPv6NeighborAdvert.sourceAddress = %v, want = %v", got, want)
-				}
-			}
-			stats[icmpInfo.typ]++
-
-			if stats[header.ICMPv6NeighborSolicit] > 0 &&
-				stats[header.ICMPv6NeighborAdvert] > 0 &&
-				stats[header.ICMPv6EchoRequest] > 0 &&
-				stats[header.ICMPv6EchoReply] > 0 {
-				return
-			}
-		}
+	for _, args := range []routeArgs{
+		{src: c.linkEP0, dst: c.linkEP1, typ: header.ICMPv6EchoRequest},
+		{src: c.linkEP1, dst: c.linkEP0, typ: header.ICMPv6EchoReply},
+	} {
+		routeICMPv6Packet(t, args, nil)
 	}
 }