Make `stack.Route` thread safe

Currently we rely on the user to take the lock on the endpoint that owns the
route, in order to modify it safely. We can instead move
`Route.RemoteLinkAddress` under `Route`'s mutex, and allow non-locking and
thread-safe access to other fields of `Route`.

PiperOrigin-RevId: 345461586

4 files changed, 26 insertions, 26 deletions

diff --git a/pkg/tcpip/network/arp/arp_test.go b/pkg/tcpip/network/arp/arp_test.go
index a738e9e1c..0fb373612 100644
--- a/pkg/tcpip/network/arp/arp_test.go
+++ b/pkg/tcpip/network/arp/arp_test.go
@@ -442,9 +442,9 @@ func (*testInterface) Promiscuous() bool {
 
 func (t *testInterface) WritePacketToRemote(remoteLinkAddr tcpip.LinkAddress, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
 	r := stack.Route{
-		NetProto:          protocol,
-		RemoteLinkAddress: remoteLinkAddr,
+		NetProto: protocol,
 	}
+	r.ResolveWith(remoteLinkAddr)
 	return t.LinkEndpoint.WritePacket(&r, gso, protocol, pkt)
 }
 
@@ -557,8 +557,8 @@ func TestLinkAddressRequest(t *testing.T) {
 				t.Fatal("expected to send a link address request")
 			}
 
-			if pkt.Route.RemoteLinkAddress != test.expectedRemoteLinkAddr {
-				t.Errorf("got pkt.Route.RemoteLinkAddress = %s, want = %s", pkt.Route.RemoteLinkAddress, test.expectedRemoteLinkAddr)
+			if got := pkt.Route.RemoteLinkAddress(); got != test.expectedRemoteLinkAddr {
+				t.Errorf("got pkt.Route.RemoteLinkAddress() = %s, want = %s", got, test.expectedRemoteLinkAddr)
 			}
 
 			rep := header.ARP(stack.PayloadSince(pkt.Pkt.NetworkHeader()))
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index 9b660eef0..2d633ca23 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -2770,8 +2770,8 @@ func TestPacketQueing(t *testing.T) {
 				if p.Proto != header.IPv4ProtocolNumber {
 					t.Errorf("got p.Proto = %d, want = %d", p.Proto, header.IPv4ProtocolNumber)
 				}
-				if p.Route.RemoteLinkAddress != host2NICLinkAddr {
-					t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, host2NICLinkAddr)
+				if got := p.Route.RemoteLinkAddress(); got != host2NICLinkAddr {
+					t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, host2NICLinkAddr)
 				}
 				checker.IPv4(t, stack.PayloadSince(p.Pkt.NetworkHeader()),
 					checker.SrcAddr(host1IPv4Addr.AddressWithPrefix.Address),
@@ -2813,8 +2813,8 @@ func TestPacketQueing(t *testing.T) {
 				if p.Proto != header.IPv4ProtocolNumber {
 					t.Errorf("got p.Proto = %d, want = %d", p.Proto, header.IPv4ProtocolNumber)
 				}
-				if p.Route.RemoteLinkAddress != host2NICLinkAddr {
-					t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, host2NICLinkAddr)
+				if got := p.Route.RemoteLinkAddress(); got != host2NICLinkAddr {
+					t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, host2NICLinkAddr)
 				}
 				checker.IPv4(t, stack.PayloadSince(p.Pkt.NetworkHeader()),
 					checker.SrcAddr(host1IPv4Addr.AddressWithPrefix.Address),
@@ -2862,8 +2862,8 @@ func TestPacketQueing(t *testing.T) {
 				if p.Proto != arp.ProtocolNumber {
 					t.Errorf("got p.Proto = %d, want = %d", p.Proto, arp.ProtocolNumber)
 				}
-				if p.Route.RemoteLinkAddress != header.EthernetBroadcastAddress {
-					t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, header.EthernetBroadcastAddress)
+				if got := p.Route.RemoteLinkAddress(); got != header.EthernetBroadcastAddress {
+					t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, header.EthernetBroadcastAddress)
 				}
 				rep := header.ARP(p.Pkt.NetworkHeader().View())
 				if got := rep.Op(); got != header.ARPRequest {
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index f19b7bec9..32adb5c83 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -150,9 +150,9 @@ func (*testInterface) Promiscuous() bool {
 
 func (t *testInterface) WritePacketToRemote(remoteLinkAddr tcpip.LinkAddress, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
 	r := stack.Route{
-		NetProto:          protocol,
-		RemoteLinkAddress: remoteLinkAddr,
+		NetProto: protocol,
 	}
+	r.ResolveWith(remoteLinkAddr)
 	return t.LinkEndpoint.WritePacket(&r, gso, protocol, pkt)
 }
 
@@ -600,8 +600,8 @@ func routeICMPv6Packet(t *testing.T, args routeArgs, fn func(*testing.T, header.
 		return
 	}
 
-	if len(args.remoteLinkAddr) != 0 && args.remoteLinkAddr != pi.Route.RemoteLinkAddress {
-		t.Errorf("got remote link address = %s, want = %s", pi.Route.RemoteLinkAddress, args.remoteLinkAddr)
+	if got := pi.Route.RemoteLinkAddress(); len(args.remoteLinkAddr) != 0 && got != args.remoteLinkAddr {
+		t.Errorf("got remote link address = %s, want = %s", got, args.remoteLinkAddr)
 	}
 
 	// Pull the full payload since network header. Needed for header.IPv6 to
@@ -1381,8 +1381,8 @@ func TestLinkAddressRequest(t *testing.T) {
 		if !ok {
 			t.Fatal("expected to send a link address request")
 		}
-		if pkt.Route.RemoteLinkAddress != test.expectedRemoteLinkAddr {
-			t.Errorf("got pkt.Route.RemoteLinkAddress = %s, want = %s", pkt.Route.RemoteLinkAddress, test.expectedRemoteLinkAddr)
+		if got := pkt.Route.RemoteLinkAddress(); got != test.expectedRemoteLinkAddr {
+			t.Errorf("got pkt.Route.RemoteLinkAddress() = %s, want = %s", got, test.expectedRemoteLinkAddr)
 		}
 		if pkt.Route.RemoteAddress != test.expectedRemoteAddr {
 			t.Errorf("got pkt.Route.RemoteAddress = %s, want = %s", pkt.Route.RemoteAddress, test.expectedRemoteAddr)
@@ -1463,8 +1463,8 @@ func TestPacketQueing(t *testing.T) {
 				if p.Proto != ProtocolNumber {
 					t.Errorf("got p.Proto = %d, want = %d", p.Proto, ProtocolNumber)
 				}
-				if p.Route.RemoteLinkAddress != host2NICLinkAddr {
-					t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, host2NICLinkAddr)
+				if got := p.Route.RemoteLinkAddress(); got != host2NICLinkAddr {
+					t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, host2NICLinkAddr)
 				}
 				checker.IPv6(t, stack.PayloadSince(p.Pkt.NetworkHeader()),
 					checker.SrcAddr(host1IPv6Addr.AddressWithPrefix.Address),
@@ -1505,8 +1505,8 @@ func TestPacketQueing(t *testing.T) {
 				if p.Proto != ProtocolNumber {
 					t.Errorf("got p.Proto = %d, want = %d", p.Proto, ProtocolNumber)
 				}
-				if p.Route.RemoteLinkAddress != host2NICLinkAddr {
-					t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, host2NICLinkAddr)
+				if got := p.Route.RemoteLinkAddress(); got != host2NICLinkAddr {
+					t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, host2NICLinkAddr)
 				}
 				checker.IPv6(t, stack.PayloadSince(p.Pkt.NetworkHeader()),
 					checker.SrcAddr(host1IPv6Addr.AddressWithPrefix.Address),
@@ -1556,8 +1556,8 @@ func TestPacketQueing(t *testing.T) {
 					t.Errorf("got Proto = %d, want = %d", p.Proto, ProtocolNumber)
 				}
 				snmc := header.SolicitedNodeAddr(host2IPv6Addr.AddressWithPrefix.Address)
-				if want := header.EthernetAddressFromMulticastIPv6Address(snmc); p.Route.RemoteLinkAddress != want {
-					t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, want)
+				if got, want := p.Route.RemoteLinkAddress(), header.EthernetAddressFromMulticastIPv6Address(snmc); got != want {
+					t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, want)
 				}
 				checker.IPv6(t, stack.PayloadSince(p.Pkt.NetworkHeader()),
 					checker.SrcAddr(host1IPv6Addr.AddressWithPrefix.Address),
diff --git a/pkg/tcpip/network/ipv6/ndp_test.go b/pkg/tcpip/network/ipv6/ndp_test.go
index e2409306f..95c626bb8 100644
--- a/pkg/tcpip/network/ipv6/ndp_test.go
+++ b/pkg/tcpip/network/ipv6/ndp_test.go
@@ -650,8 +650,8 @@ func TestNeighorSolicitationResponse(t *testing.T) {
 						if p.Route.RemoteAddress != respNSDst {
 							t.Errorf("got p.Route.RemoteAddress = %s, want = %s", p.Route.RemoteAddress, respNSDst)
 						}
-						if want := header.EthernetAddressFromMulticastIPv6Address(respNSDst); p.Route.RemoteLinkAddress != want {
-							t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, want)
+						if got, want := p.Route.RemoteLinkAddress(), header.EthernetAddressFromMulticastIPv6Address(respNSDst); got != want {
+							t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, want)
 						}
 
 						checker.IPv6(t, stack.PayloadSince(p.Pkt.NetworkHeader()),
@@ -706,8 +706,8 @@ func TestNeighorSolicitationResponse(t *testing.T) {
 					if p.Route.RemoteAddress != test.naDst {
 						t.Errorf("got p.Route.RemoteAddress = %s, want = %s", p.Route.RemoteAddress, test.naDst)
 					}
-					if p.Route.RemoteLinkAddress != test.naDstLinkAddr {
-						t.Errorf("got p.Route.RemoteLinkAddress = %s, want = %s", p.Route.RemoteLinkAddress, test.naDstLinkAddr)
+					if got := p.Route.RemoteLinkAddress(); got != test.naDstLinkAddr {
+						t.Errorf("got p.Route.RemoteLinkAddress() = %s, want = %s", got, test.naDstLinkAddr)
 					}
 
 					checker.IPv6(t, stack.PayloadSince(p.Pkt.NetworkHeader()),