3 files changed, 40 insertions, 22 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index e9ff70d04..cc045c7a9 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -64,6 +64,7 @@ const (
 
 var ipv4BroadcastAddr = header.IPv4Broadcast.WithPrefix()
 
+var _ stack.LinkResolvableNetworkEndpoint = (*endpoint)(nil)
 var _ stack.GroupAddressableEndpoint = (*endpoint)(nil)
 var _ stack.AddressableEndpoint = (*endpoint)(nil)
 var _ stack.NetworkEndpoint = (*endpoint)(nil)
@@ -87,6 +88,21 @@ type endpoint struct {
 	}
 }
 
+// HandleLinkResolutionFailure implements stack.LinkResolvableNetworkEndpoint.
+func (e *endpoint) HandleLinkResolutionFailure(pkt *stack.PacketBuffer) {
+	// handleControl expects the entire offending packet to be in the packet
+	// buffer's data field.
+	pkt = stack.NewPacketBuffer(stack.PacketBufferOptions{
+		Data: buffer.NewVectorisedView(pkt.Size(), pkt.Views()),
+	})
+	pkt.NICID = e.nic.ID()
+	pkt.NetworkProtocolNumber = ProtocolNumber
+	// Use the same control type as an ICMPv4 destination host unreachable error
+	// since the host is considered unreachable if we cannot resolve the link
+	// address to the next hop.
+	e.handleControl(stack.ControlNoRoute, 0, pkt)
+}
+
 // NewEndpoint creates a new ipv4 endpoint.
 func (p *protocol) NewEndpoint(nic stack.NetworkInterface, _ stack.LinkAddressCache, _ stack.NUDHandler, dispatcher stack.TransportDispatcher) stack.NetworkEndpoint {
 	e := &endpoint{
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index bbce1ef78..0ec0a0fef 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -645,29 +645,18 @@ func TestLinkResolution(t *testing.T) {
 		t.Fatalf("NewEndpoint(_) = (_, %s), want = (_, nil)", err)
 	}
 
-	for {
-		_, resCh, err := ep.Write(payload, tcpip.WriteOptions{To: &tcpip.FullAddress{NIC: nicID, Addr: lladdr1}})
-		if resCh != nil {
-			if err != tcpip.ErrNoLinkAddress {
-				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, remoteLinkAddr: header.EthernetAddressFromMulticastIPv6Address(header.SolicitedNodeAddr(lladdr1))},
-				{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)
-					}
-				})
+	if _, err := ep.Write(payload, tcpip.WriteOptions{To: &tcpip.FullAddress{NIC: nicID, Addr: lladdr1}}); err != nil {
+		t.Fatalf("ep.Write(_): %s", err)
+	}
+	for _, args := range []routeArgs{
+		{src: c.linkEP0, dst: c.linkEP1, typ: header.ICMPv6NeighborSolicit, remoteLinkAddr: header.EthernetAddressFromMulticastIPv6Address(header.SolicitedNodeAddr(lladdr1))},
+		{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
-		}
-		if err != nil {
-			t.Fatalf("ep.Write(_) = (_, _, %s)", err)
-		}
-		break
+		})
 	}
 
 	for _, args := range []routeArgs{
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index f2018d073..2f82c3d5f 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -163,6 +163,7 @@ func getLabel(addr tcpip.Address) uint8 {
 	panic(fmt.Sprintf("should have a label for address = %s", addr))
 }
 
+var _ stack.LinkResolvableNetworkEndpoint = (*endpoint)(nil)
 var _ stack.GroupAddressableEndpoint = (*endpoint)(nil)
 var _ stack.AddressableEndpoint = (*endpoint)(nil)
 var _ stack.NetworkEndpoint = (*endpoint)(nil)
@@ -224,6 +225,18 @@ type OpaqueInterfaceIdentifierOptions struct {
 	SecretKey []byte
 }
 
+// HandleLinkResolutionFailure implements stack.LinkResolvableNetworkEndpoint.
+func (e *endpoint) HandleLinkResolutionFailure(pkt *stack.PacketBuffer) {
+	// handleControl expects the entire offending packet to be in the packet
+	// buffer's data field.
+	pkt = stack.NewPacketBuffer(stack.PacketBufferOptions{
+		Data: buffer.NewVectorisedView(pkt.Size(), pkt.Views()),
+	})
+	pkt.NICID = e.nic.ID()
+	pkt.NetworkProtocolNumber = ProtocolNumber
+	e.handleControl(stack.ControlAddressUnreachable, 0, pkt)
+}
+
 // onAddressAssignedLocked handles an address being assigned.
 //
 // Precondition: e.mu must be exclusively locked.