Implement LinkAddressResolver on NetworkEndpoints

This removes the need to provide the link address request with the NIC
the request is being performed on since the NetworkEndpoints already
have a reference to the NIC.

PiperOrigin-RevId: 354721940

3 files changed, 28 insertions, 35 deletions

diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index 7298bd061..8db2454d3 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -290,7 +290,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool) {
 			received.invalid.Increment()
 			return
 		} else if e.nud != nil {
-			e.nud.HandleProbe(srcAddr, header.IPv6ProtocolNumber, sourceLinkAddr, e.protocol)
+			e.nud.HandleProbe(srcAddr, header.IPv6ProtocolNumber, sourceLinkAddr, e)
 		} else {
 			e.linkAddrCache.AddLinkAddress(srcAddr, sourceLinkAddr)
 		}
@@ -578,7 +578,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool) {
 			if e.nud != nil {
 				// A RS with a specified source IP address modifies the NUD state
 				// machine in the same way a reachability probe would.
-				e.nud.HandleProbe(srcAddr, ProtocolNumber, sourceLinkAddr, e.protocol)
+				e.nud.HandleProbe(srcAddr, ProtocolNumber, sourceLinkAddr, e)
 			}
 		}
 
@@ -628,7 +628,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool) {
 		// If the RA has the source link layer option, update the link address
 		// cache with the link address for the advertised router.
 		if len(sourceLinkAddr) != 0 && e.nud != nil {
-			e.nud.HandleProbe(routerAddr, ProtocolNumber, sourceLinkAddr, e.protocol)
+			e.nud.HandleProbe(routerAddr, ProtocolNumber, sourceLinkAddr, e)
 		}
 
 		e.mu.Lock()
@@ -694,24 +694,13 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool) {
 	}
 }
 
-var _ stack.LinkAddressResolver = (*protocol)(nil)
-
 // LinkAddressProtocol implements stack.LinkAddressResolver.
-func (*protocol) LinkAddressProtocol() tcpip.NetworkProtocolNumber {
+func (*endpoint) LinkAddressProtocol() tcpip.NetworkProtocolNumber {
 	return header.IPv6ProtocolNumber
 }
 
 // LinkAddressRequest implements stack.LinkAddressResolver.
-func (p *protocol) LinkAddressRequest(targetAddr, localAddr tcpip.Address, remoteLinkAddr tcpip.LinkAddress, nic stack.NetworkInterface) tcpip.Error {
-	nicID := nic.ID()
-
-	p.mu.Lock()
-	netEP, ok := p.mu.eps[nicID]
-	p.mu.Unlock()
-	if !ok {
-		return &tcpip.ErrNotConnected{}
-	}
-
+func (e *endpoint) LinkAddressRequest(targetAddr, localAddr tcpip.Address, remoteLinkAddr tcpip.LinkAddress) tcpip.Error {
 	remoteAddr := targetAddr
 	if len(remoteLinkAddr) == 0 {
 		remoteAddr = header.SolicitedNodeAddr(targetAddr)
@@ -719,22 +708,22 @@ func (p *protocol) LinkAddressRequest(targetAddr, localAddr tcpip.Address, remot
 	}
 
 	if len(localAddr) == 0 {
-		addressEndpoint := netEP.AcquireOutgoingPrimaryAddress(remoteAddr, false /* allowExpired */)
+		addressEndpoint := e.AcquireOutgoingPrimaryAddress(remoteAddr, false /* allowExpired */)
 		if addressEndpoint == nil {
 			return &tcpip.ErrNetworkUnreachable{}
 		}
 
 		localAddr = addressEndpoint.AddressWithPrefix().Address
-	} else if p.stack.CheckLocalAddress(nicID, ProtocolNumber, localAddr) == 0 {
+	} else if e.protocol.stack.CheckLocalAddress(e.nic.ID(), ProtocolNumber, localAddr) == 0 {
 		return &tcpip.ErrBadLocalAddress{}
 	}
 
 	optsSerializer := header.NDPOptionsSerializer{
-		header.NDPSourceLinkLayerAddressOption(nic.LinkAddress()),
+		header.NDPSourceLinkLayerAddressOption(e.nic.LinkAddress()),
 	}
 	neighborSolicitSize := header.ICMPv6NeighborSolicitMinimumSize + optsSerializer.Length()
 	pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
-		ReserveHeaderBytes: int(nic.MaxHeaderLength()) + header.IPv6FixedHeaderSize + neighborSolicitSize,
+		ReserveHeaderBytes: int(e.nic.MaxHeaderLength()) + header.IPv6FixedHeaderSize + neighborSolicitSize,
 	})
 	pkt.TransportProtocolNumber = header.ICMPv6ProtocolNumber
 	packet := header.ICMPv6(pkt.TransportHeader().Push(neighborSolicitSize))
@@ -751,9 +740,9 @@ func (p *protocol) LinkAddressRequest(targetAddr, localAddr tcpip.Address, remot
 		panic(fmt.Sprintf("failed to add IP header: %s", err))
 	}
 
-	stat := netEP.stats.icmp.packetsSent
+	stat := e.stats.icmp.packetsSent
 
-	if err := nic.WritePacketToRemote(remoteLinkAddr, nil /* gso */, ProtocolNumber, pkt); err != nil {
+	if err := e.nic.WritePacketToRemote(remoteLinkAddr, nil /* gso */, ProtocolNumber, pkt); err != nil {
 		stat.dropped.Increment()
 		return err
 	}
@@ -763,7 +752,7 @@ func (p *protocol) LinkAddressRequest(targetAddr, localAddr tcpip.Address, remot
 }
 
 // ResolveStaticAddress implements stack.LinkAddressResolver.
-func (*protocol) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bool) {
+func (*endpoint) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bool) {
 	if header.IsV6MulticastAddress(addr) {
 		return header.EthernetAddressFromMulticastIPv6Address(addr), true
 	}
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index db1c2e663..a5c88444e 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -1346,29 +1346,32 @@ func TestLinkAddressRequest(t *testing.T) {
 			s := stack.New(stack.Options{
 				NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
 			})
-			p := s.NetworkProtocolInstance(ProtocolNumber)
-			linkRes, ok := p.(stack.LinkAddressResolver)
-			if !ok {
-				t.Fatalf("expected IPv6 protocol to implement stack.LinkAddressResolver")
-			}
 
 			linkEP := channel.New(defaultChannelSize, defaultMTU, linkAddr0)
 			if err := s.CreateNIC(nicID, linkEP); err != nil {
 				t.Fatalf("s.CreateNIC(%d, _): %s", nicID, err)
 			}
+
+			ep, err := s.GetNetworkEndpoint(nicID, ProtocolNumber)
+			if err != nil {
+				t.Fatalf("s.GetNetworkEndpoint(%d, %d): %s", nicID, ProtocolNumber, err)
+			}
+			linkRes, ok := ep.(stack.LinkAddressResolver)
+			if !ok {
+				t.Fatalf("expected %T to implement stack.LinkAddressResolver", ep)
+			}
+
 			if len(test.nicAddr) != 0 {
 				if err := s.AddAddress(nicID, ProtocolNumber, test.nicAddr); err != nil {
 					t.Fatalf("s.AddAddress(%d, %d, %s): %s", nicID, ProtocolNumber, test.nicAddr, err)
 				}
 			}
 
-			// We pass a test network interface to LinkAddressRequest with the same NIC
-			// ID and link endpoint used by the NIC we created earlier so that we can
-			// mock a link address request and observe the packets sent to the link
-			// endpoint even though the stack uses the real NIC.
-			err := linkRes.LinkAddressRequest(lladdr0, test.localAddr, test.remoteLinkAddr, &testInterface{LinkEndpoint: linkEP, nicID: nicID})
-			if diff := cmp.Diff(test.expectedErr, err); diff != "" {
-				t.Fatalf("unexpected error from p.LinkAddressRequest(%s, %s, %s, _), (-want, +got):\n%s", lladdr0, test.localAddr, test.remoteLinkAddr, diff)
+			{
+				err := linkRes.LinkAddressRequest(lladdr0, test.localAddr, test.remoteLinkAddr)
+				if diff := cmp.Diff(test.expectedErr, err); diff != "" {
+					t.Fatalf("unexpected error from p.LinkAddressRequest(%s, %s, %s, _), (-want, +got):\n%s", lladdr0, test.localAddr, test.remoteLinkAddr, diff)
+				}
 			}
 
 			if test.expectedErr != nil {
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index caa62b3a2..b55a35525 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -164,6 +164,7 @@ func getLabel(addr tcpip.Address) uint8 {
 	panic(fmt.Sprintf("should have a label for address = %s", addr))
 }
 
+var _ stack.LinkAddressResolver = (*endpoint)(nil)
 var _ stack.LinkResolvableNetworkEndpoint = (*endpoint)(nil)
 var _ stack.GroupAddressableEndpoint = (*endpoint)(nil)
 var _ stack.AddressableEndpoint = (*endpoint)(nil)