Add support for a subnet prefix length on interface network addresses

This allows the user code to add a network address with a subnet prefix length.
The prefix length value is stored in the network endpoint and provided back to
the user in the ProtocolAddress type.

PiperOrigin-RevId: 259807693

2 files changed, 19 insertions, 3 deletions

diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index d46d68e73..726362c87 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -99,7 +99,11 @@ func TestICMPCounts(t *testing.T) {
 		}},
 	)
 
-	ep, err := s.NetworkProtocolInstance(ProtocolNumber).NewEndpoint(0, lladdr1, &stubLinkAddressCache{}, &stubDispatcher{}, nil)
+	netProto := s.NetworkProtocolInstance(ProtocolNumber)
+	if netProto == nil {
+		t.Fatalf("cannot find protocol instance for network protocol %d", ProtocolNumber)
+	}
+	ep, err := netProto.NewEndpoint(0, tcpip.AddressWithPrefix{lladdr1, netProto.DefaultPrefixLen()}, &stubLinkAddressCache{}, &stubDispatcher{}, nil)
 	if err != nil {
 		t.Fatalf("NewEndpoint(_) = _, %s, want = _, nil", err)
 	}
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index e3e8739fd..331a8bdaa 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -46,6 +46,7 @@ const (
 type endpoint struct {
 	nicid         tcpip.NICID
 	id            stack.NetworkEndpointID
+	prefixLen     int
 	linkEP        stack.LinkEndpoint
 	linkAddrCache stack.LinkAddressCache
 	dispatcher    stack.TransportDispatcher
@@ -72,6 +73,11 @@ func (e *endpoint) ID() *stack.NetworkEndpointID {
 	return &e.id
 }
 
+// PrefixLen returns the ipv6 endpoint subnet prefix length in bits.
+func (e *endpoint) PrefixLen() int {
+	return e.prefixLen
+}
+
 // Capabilities implements stack.NetworkEndpoint.Capabilities.
 func (e *endpoint) Capabilities() stack.LinkEndpointCapabilities {
 	return e.linkEP.Capabilities()
@@ -172,6 +178,11 @@ func (p *protocol) MinimumPacketSize() int {
 	return header.IPv6MinimumSize
 }
 
+// DefaultPrefixLen returns the IPv6 default prefix length.
+func (p *protocol) DefaultPrefixLen() int {
+	return header.IPv6AddressSize * 8
+}
+
 // ParseAddresses implements NetworkProtocol.ParseAddresses.
 func (*protocol) ParseAddresses(v buffer.View) (src, dst tcpip.Address) {
 	h := header.IPv6(v)
@@ -179,10 +190,11 @@ func (*protocol) ParseAddresses(v buffer.View) (src, dst tcpip.Address) {
 }
 
 // NewEndpoint creates a new ipv6 endpoint.
-func (p *protocol) NewEndpoint(nicid tcpip.NICID, addr tcpip.Address, linkAddrCache stack.LinkAddressCache, dispatcher stack.TransportDispatcher, linkEP stack.LinkEndpoint) (stack.NetworkEndpoint, *tcpip.Error) {
+func (p *protocol) NewEndpoint(nicid tcpip.NICID, addrWithPrefix tcpip.AddressWithPrefix, linkAddrCache stack.LinkAddressCache, dispatcher stack.TransportDispatcher, linkEP stack.LinkEndpoint) (stack.NetworkEndpoint, *tcpip.Error) {
 	return &endpoint{
 		nicid:         nicid,
-		id:            stack.NetworkEndpointID{LocalAddress: addr},
+		id:            stack.NetworkEndpointID{LocalAddress: addrWithPrefix.Address},
+		prefixLen:     addrWithPrefix.PrefixLen,
 		linkEP:        linkEP,
 		linkAddrCache: linkAddrCache,
 		dispatcher:    dispatcher,