Add ability to send unicast ARP requests and Neighbor Solicitations

The previous implementation of LinkAddressRequest only supported sending
broadcast ARP requests and multicast Neighbor Solicitations. The ability to
send these packets as unicast is required for Neighbor Unreachability
Detection.

Tests:
 pkg/tcpip/network/arp:arp_test
 - TestLinkAddressRequest

 pkg/tcpip/network/ipv6:ipv6_test
 - TestLinkAddressRequest

Updates #1889
Updates #1894
Updates #1895
Updates #1947
Updates #1948
Updates #1949
Updates #1950

PiperOrigin-RevId: 323451569

1 files changed, 10 insertions, 8 deletions

diff --git a/pkg/tcpip/stack/forwarder_test.go b/pkg/tcpip/stack/forwarder_test.go
index bca1d940b..c962693f5 100644
--- a/pkg/tcpip/stack/forwarder_test.go
+++ b/pkg/tcpip/stack/forwarder_test.go
@@ -121,10 +121,12 @@ func (*fwdTestNetworkEndpoint) Close() {}
 type fwdTestNetworkProtocol struct {
 	addrCache              *linkAddrCache
 	addrResolveDelay       time.Duration
-	onLinkAddressResolved  func(cache *linkAddrCache, addr tcpip.Address)
+	onLinkAddressResolved  func(cache *linkAddrCache, addr tcpip.Address, _ tcpip.LinkAddress)
 	onResolveStaticAddress func(tcpip.Address) (tcpip.LinkAddress, bool)
 }
 
+var _ LinkAddressResolver = (*fwdTestNetworkProtocol)(nil)
+
 func (f *fwdTestNetworkProtocol) Number() tcpip.NetworkProtocolNumber {
 	return fwdTestNetNumber
 }
@@ -174,10 +176,10 @@ func (f *fwdTestNetworkProtocol) Close() {}
 
 func (f *fwdTestNetworkProtocol) Wait() {}
 
-func (f *fwdTestNetworkProtocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP LinkEndpoint) *tcpip.Error {
+func (f *fwdTestNetworkProtocol) LinkAddressRequest(addr, localAddr tcpip.Address, remoteLinkAddr tcpip.LinkAddress, linkEP LinkEndpoint) *tcpip.Error {
 	if f.addrCache != nil && f.onLinkAddressResolved != nil {
 		time.AfterFunc(f.addrResolveDelay, func() {
-			f.onLinkAddressResolved(f.addrCache, addr)
+			f.onLinkAddressResolved(f.addrCache, addr, remoteLinkAddr)
 		})
 	}
 	return nil
@@ -405,7 +407,7 @@ func TestForwardingWithFakeResolver(t *testing.T) {
 	// Create a network protocol with a fake resolver.
 	proto := &fwdTestNetworkProtocol{
 		addrResolveDelay: 500 * time.Millisecond,
-		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address) {
+		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address, _ tcpip.LinkAddress) {
 			// Any address will be resolved to the link address "c".
 			cache.add(tcpip.FullAddress{NIC: 2, Addr: addr}, "c")
 		},
@@ -463,7 +465,7 @@ func TestForwardingWithFakeResolverPartialTimeout(t *testing.T) {
 	// Create a network protocol with a fake resolver.
 	proto := &fwdTestNetworkProtocol{
 		addrResolveDelay: 500 * time.Millisecond,
-		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address) {
+		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address, _ tcpip.LinkAddress) {
 			// Only packets to address 3 will be resolved to the
 			// link address "c".
 			if addr == "\x03" {
@@ -515,7 +517,7 @@ func TestForwardingWithFakeResolverTwoPackets(t *testing.T) {
 	// Create a network protocol with a fake resolver.
 	proto := &fwdTestNetworkProtocol{
 		addrResolveDelay: 500 * time.Millisecond,
-		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address) {
+		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address, _ tcpip.LinkAddress) {
 			// Any packets will be resolved to the link address "c".
 			cache.add(tcpip.FullAddress{NIC: 2, Addr: addr}, "c")
 		},
@@ -559,7 +561,7 @@ func TestForwardingWithFakeResolverManyPackets(t *testing.T) {
 	// Create a network protocol with a fake resolver.
 	proto := &fwdTestNetworkProtocol{
 		addrResolveDelay: 500 * time.Millisecond,
-		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address) {
+		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address, _ tcpip.LinkAddress) {
 			// Any packets will be resolved to the link address "c".
 			cache.add(tcpip.FullAddress{NIC: 2, Addr: addr}, "c")
 		},
@@ -616,7 +618,7 @@ func TestForwardingWithFakeResolverManyResolutions(t *testing.T) {
 	// Create a network protocol with a fake resolver.
 	proto := &fwdTestNetworkProtocol{
 		addrResolveDelay: 500 * time.Millisecond,
-		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address) {
+		onLinkAddressResolved: func(cache *linkAddrCache, addr tcpip.Address, _ tcpip.LinkAddress) {
 			// Any packets will be resolved to the link address "c".
 			cache.add(tcpip.FullAddress{NIC: 2, Addr: addr}, "c")
 		},