Support add/remove IPv6 multicast group sock opt

IPv4 was always supported but UDP never supported joining/leaving IPv6
multicast groups via socket options.

Add: IPPROTO_IPV6, IPV6_JOIN_GROUP/IPV6_ADD_MEMBERSHIP
Remove: IPPROTO_IPV6, IPV6_LEAVE_GROUP/IPV6_DROP_MEMBERSHIP

Test: integration_test.TestUDPAddRemoveMembershipSocketOption
PiperOrigin-RevId: 350396072

2 files changed, 332 insertions, 156 deletions

diff --git a/pkg/tcpip/tests/integration/multicast_broadcast_test.go b/pkg/tcpip/tests/integration/multicast_broadcast_test.go
index 2e59f6a42..20f8a7e6c 100644
--- a/pkg/tcpip/tests/integration/multicast_broadcast_test.go
+++ b/pkg/tcpip/tests/integration/multicast_broadcast_test.go
@@ -35,6 +35,9 @@ import (
 const (
 	defaultMTU = 1280
 	ttl        = 255
+
+	remotePort = 5555
+	localPort  = 80
 )
 
 var (
@@ -151,11 +154,11 @@ func TestPingMulticastBroadcast(t *testing.T) {
 			}
 			ipv4ProtoAddr := tcpip.ProtocolAddress{Protocol: header.IPv4ProtocolNumber, AddressWithPrefix: ipv4Addr}
 			if err := s.AddProtocolAddress(nicID, ipv4ProtoAddr); err != nil {
-				t.Fatalf("AddProtocolAddress(%d, %+v): %s", nicID, ipv4ProtoAddr, err)
+				t.Fatalf("AddProtocolAddress(%d, %#v): %s", nicID, ipv4ProtoAddr, err)
 			}
 			ipv6ProtoAddr := tcpip.ProtocolAddress{Protocol: header.IPv6ProtocolNumber, AddressWithPrefix: ipv6Addr}
 			if err := s.AddProtocolAddress(nicID, ipv6ProtoAddr); err != nil {
-				t.Fatalf("AddProtocolAddress(%d, %+v): %s", nicID, ipv6ProtoAddr, err)
+				t.Fatalf("AddProtocolAddress(%d, %#v): %s", nicID, ipv6ProtoAddr, err)
 			}
 
 			// Default routes for IPv4 and IPv6 so ICMP can find a route to the remote
@@ -215,163 +218,219 @@ func TestPingMulticastBroadcast(t *testing.T) {
 
 }
 
+func rxIPv4UDP(e *channel.Endpoint, src, dst tcpip.Address, data []byte) {
+	payloadLen := header.UDPMinimumSize + len(data)
+	totalLen := header.IPv4MinimumSize + payloadLen
+	hdr := buffer.NewPrependable(totalLen)
+	u := header.UDP(hdr.Prepend(payloadLen))
+	u.Encode(&header.UDPFields{
+		SrcPort: remotePort,
+		DstPort: localPort,
+		Length:  uint16(payloadLen),
+	})
+	copy(u.Payload(), data)
+	sum := header.PseudoHeaderChecksum(udp.ProtocolNumber, src, dst, uint16(payloadLen))
+	sum = header.Checksum(data, sum)
+	u.SetChecksum(^u.CalculateChecksum(sum))
+
+	ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize))
+	ip.Encode(&header.IPv4Fields{
+		TotalLength: uint16(totalLen),
+		Protocol:    uint8(udp.ProtocolNumber),
+		TTL:         ttl,
+		SrcAddr:     src,
+		DstAddr:     dst,
+	})
+	ip.SetChecksum(^ip.CalculateChecksum())
+
+	e.InjectInbound(header.IPv4ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
+		Data: hdr.View().ToVectorisedView(),
+	}))
+}
+
+func rxIPv6UDP(e *channel.Endpoint, src, dst tcpip.Address, data []byte) {
+	payloadLen := header.UDPMinimumSize + len(data)
+	hdr := buffer.NewPrependable(header.IPv6MinimumSize + payloadLen)
+	u := header.UDP(hdr.Prepend(payloadLen))
+	u.Encode(&header.UDPFields{
+		SrcPort: remotePort,
+		DstPort: localPort,
+		Length:  uint16(payloadLen),
+	})
+	copy(u.Payload(), data)
+	sum := header.PseudoHeaderChecksum(udp.ProtocolNumber, src, dst, uint16(payloadLen))
+	sum = header.Checksum(data, sum)
+	u.SetChecksum(^u.CalculateChecksum(sum))
+
+	ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
+	ip.Encode(&header.IPv6Fields{
+		PayloadLength:     uint16(payloadLen),
+		TransportProtocol: udp.ProtocolNumber,
+		HopLimit:          ttl,
+		SrcAddr:           src,
+		DstAddr:           dst,
+	})
+
+	e.InjectInbound(header.IPv6ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
+		Data: hdr.View().ToVectorisedView(),
+	}))
+}
+
 // TestIncomingMulticastAndBroadcast tests receiving a packet destined to some
 // multicast or broadcast address.
 func TestIncomingMulticastAndBroadcast(t *testing.T) {
-	const (
-		nicID      = 1
-		remotePort = 5555
-		localPort  = 80
-	)
+	const nicID = 1
 
 	data := []byte{1, 2, 3, 4}
 
-	rxIPv4UDP := func(e *channel.Endpoint, dst tcpip.Address) {
-		payloadLen := header.UDPMinimumSize + len(data)
-		totalLen := header.IPv4MinimumSize + payloadLen
-		hdr := buffer.NewPrependable(totalLen)
-		u := header.UDP(hdr.Prepend(payloadLen))
-		u.Encode(&header.UDPFields{
-			SrcPort: remotePort,
-			DstPort: localPort,
-			Length:  uint16(payloadLen),
-		})
-		copy(u.Payload(), data)
-		sum := header.PseudoHeaderChecksum(udp.ProtocolNumber, remoteIPv4Addr, dst, uint16(payloadLen))
-		sum = header.Checksum(data, sum)
-		u.SetChecksum(^u.CalculateChecksum(sum))
-
-		ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize))
-		ip.Encode(&header.IPv4Fields{
-			TotalLength: uint16(totalLen),
-			Protocol:    uint8(udp.ProtocolNumber),
-			TTL:         ttl,
-			SrcAddr:     remoteIPv4Addr,
-			DstAddr:     dst,
-		})
-		ip.SetChecksum(^ip.CalculateChecksum())
-
-		e.InjectInbound(header.IPv4ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
-			Data: hdr.View().ToVectorisedView(),
-		}))
-	}
-
-	rxIPv6UDP := func(e *channel.Endpoint, dst tcpip.Address) {
-		payloadLen := header.UDPMinimumSize + len(data)
-		hdr := buffer.NewPrependable(header.IPv6MinimumSize + payloadLen)
-		u := header.UDP(hdr.Prepend(payloadLen))
-		u.Encode(&header.UDPFields{
-			SrcPort: remotePort,
-			DstPort: localPort,
-			Length:  uint16(payloadLen),
-		})
-		copy(u.Payload(), data)
-		sum := header.PseudoHeaderChecksum(udp.ProtocolNumber, remoteIPv6Addr, dst, uint16(payloadLen))
-		sum = header.Checksum(data, sum)
-		u.SetChecksum(^u.CalculateChecksum(sum))
-
-		ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
-		ip.Encode(&header.IPv6Fields{
-			PayloadLength:     uint16(payloadLen),
-			TransportProtocol: udp.ProtocolNumber,
-			HopLimit:          ttl,
-			SrcAddr:           remoteIPv6Addr,
-			DstAddr:           dst,
-		})
-
-		e.InjectInbound(header.IPv6ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
-			Data: hdr.View().ToVectorisedView(),
-		}))
-	}
-
 	tests := []struct {
-		name     string
-		bindAddr tcpip.Address
-		dstAddr  tcpip.Address
-		expectRx bool
+		name       string
+		proto      tcpip.NetworkProtocolNumber
+		remoteAddr tcpip.Address
+		localAddr  tcpip.AddressWithPrefix
+		rxUDP      func(*channel.Endpoint, tcpip.Address, tcpip.Address, []byte)
+		bindAddr   tcpip.Address
+		dstAddr    tcpip.Address
+		expectRx   bool
 	}{
 		{
-			name:     "IPv4 unicast binding to unicast",
-			bindAddr: ipv4Addr.Address,
-			dstAddr:  ipv4Addr.Address,
-			expectRx: true,
+			name:       "IPv4 unicast binding to unicast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   ipv4Addr.Address,
+			dstAddr:    ipv4Addr.Address,
+			expectRx:   true,
 		},
 		{
-			name:     "IPv4 unicast binding to broadcast",
-			bindAddr: header.IPv4Broadcast,
-			dstAddr:  ipv4Addr.Address,
-			expectRx: false,
+			name:       "IPv4 unicast binding to broadcast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   header.IPv4Broadcast,
+			dstAddr:    ipv4Addr.Address,
+			expectRx:   false,
 		},
 		{
-			name:     "IPv4 unicast binding to wildcard",
-			dstAddr:  ipv4Addr.Address,
-			expectRx: true,
+			name:       "IPv4 unicast binding to wildcard",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			dstAddr:    ipv4Addr.Address,
+			expectRx:   true,
 		},
 
 		{
-			name:     "IPv4 directed broadcast binding to subnet broadcast",
-			bindAddr: ipv4SubnetBcast,
-			dstAddr:  ipv4SubnetBcast,
-			expectRx: true,
+			name:       "IPv4 directed broadcast binding to subnet broadcast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   ipv4SubnetBcast,
+			dstAddr:    ipv4SubnetBcast,
+			expectRx:   true,
 		},
 		{
-			name:     "IPv4 directed broadcast binding to broadcast",
-			bindAddr: header.IPv4Broadcast,
-			dstAddr:  ipv4SubnetBcast,
-			expectRx: false,
+			name:       "IPv4 directed broadcast binding to broadcast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   header.IPv4Broadcast,
+			dstAddr:    ipv4SubnetBcast,
+			expectRx:   false,
 		},
 		{
-			name:     "IPv4 directed broadcast binding to wildcard",
-			dstAddr:  ipv4SubnetBcast,
-			expectRx: true,
+			name:       "IPv4 directed broadcast binding to wildcard",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			dstAddr:    ipv4SubnetBcast,
+			expectRx:   true,
 		},
 
 		{
-			name:     "IPv4 broadcast binding to broadcast",
-			bindAddr: header.IPv4Broadcast,
-			dstAddr:  header.IPv4Broadcast,
-			expectRx: true,
+			name:       "IPv4 broadcast binding to broadcast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   header.IPv4Broadcast,
+			dstAddr:    header.IPv4Broadcast,
+			expectRx:   true,
 		},
 		{
-			name:     "IPv4 broadcast binding to subnet broadcast",
-			bindAddr: ipv4SubnetBcast,
-			dstAddr:  header.IPv4Broadcast,
-			expectRx: false,
+			name:       "IPv4 broadcast binding to subnet broadcast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   ipv4SubnetBcast,
+			dstAddr:    header.IPv4Broadcast,
+			expectRx:   false,
 		},
 		{
-			name:     "IPv4 broadcast binding to wildcard",
-			dstAddr:  ipv4SubnetBcast,
-			expectRx: true,
+			name:       "IPv4 broadcast binding to wildcard",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			dstAddr:    ipv4SubnetBcast,
+			expectRx:   true,
 		},
 
 		{
-			name:     "IPv4 all-systems multicast binding to all-systems multicast",
-			bindAddr: header.IPv4AllSystems,
-			dstAddr:  header.IPv4AllSystems,
-			expectRx: true,
+			name:       "IPv4 all-systems multicast binding to all-systems multicast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   header.IPv4AllSystems,
+			dstAddr:    header.IPv4AllSystems,
+			expectRx:   true,
 		},
 		{
-			name:     "IPv4 all-systems multicast binding to wildcard",
-			dstAddr:  header.IPv4AllSystems,
-			expectRx: true,
+			name:       "IPv4 all-systems multicast binding to wildcard",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			dstAddr:    header.IPv4AllSystems,
+			expectRx:   true,
 		},
 		{
-			name:     "IPv4 all-systems multicast binding to unicast",
-			bindAddr: ipv4Addr.Address,
-			dstAddr:  header.IPv4AllSystems,
-			expectRx: false,
+			name:       "IPv4 all-systems multicast binding to unicast",
+			proto:      header.IPv4ProtocolNumber,
+			remoteAddr: remoteIPv4Addr,
+			localAddr:  ipv4Addr,
+			rxUDP:      rxIPv4UDP,
+			bindAddr:   ipv4Addr.Address,
+			dstAddr:    header.IPv4AllSystems,
+			expectRx:   false,
 		},
 
 		// IPv6 has no notion of a broadcast.
 		{
-			name:     "IPv6 unicast binding to wildcard",
-			dstAddr:  ipv6Addr.Address,
-			expectRx: true,
+			name:       "IPv6 unicast binding to wildcard",
+			dstAddr:    ipv6Addr.Address,
+			proto:      header.IPv6ProtocolNumber,
+			remoteAddr: remoteIPv6Addr,
+			localAddr:  ipv6Addr,
+			rxUDP:      rxIPv6UDP,
+			expectRx:   true,
 		},
 		{
-			name:     "IPv6 broadcast-like address binding to wildcard",
-			dstAddr:  ipv6SubnetBcast,
-			expectRx: false,
+			name:       "IPv6 broadcast-like address binding to wildcard",
+			dstAddr:    ipv6SubnetBcast,
+			proto:      header.IPv6ProtocolNumber,
+			remoteAddr: remoteIPv6Addr,
+			localAddr:  ipv6Addr,
+			rxUDP:      rxIPv6UDP,
+			expectRx:   false,
 		},
 	}
 
@@ -385,41 +444,24 @@ func TestIncomingMulticastAndBroadcast(t *testing.T) {
 			if err := s.CreateNIC(nicID, e); err != nil {
 				t.Fatalf("CreateNIC(%d, _): %s", nicID, err)
 			}
-			ipv4ProtoAddr := tcpip.ProtocolAddress{Protocol: header.IPv4ProtocolNumber, AddressWithPrefix: ipv4Addr}
-			if err := s.AddProtocolAddress(nicID, ipv4ProtoAddr); err != nil {
-				t.Fatalf("AddProtocolAddress(%d, %+v): %s", nicID, ipv4ProtoAddr, err)
-			}
-			ipv6ProtoAddr := tcpip.ProtocolAddress{Protocol: header.IPv6ProtocolNumber, AddressWithPrefix: ipv6Addr}
-			if err := s.AddProtocolAddress(nicID, ipv6ProtoAddr); err != nil {
-				t.Fatalf("AddProtocolAddress(%d, %+v): %s", nicID, ipv6ProtoAddr, err)
-			}
-
-			var netproto tcpip.NetworkProtocolNumber
-			var rxUDP func(*channel.Endpoint, tcpip.Address)
-			switch l := len(test.dstAddr); l {
-			case header.IPv4AddressSize:
-				netproto = header.IPv4ProtocolNumber
-				rxUDP = rxIPv4UDP
-			case header.IPv6AddressSize:
-				netproto = header.IPv6ProtocolNumber
-				rxUDP = rxIPv6UDP
-			default:
-				t.Fatalf("got unexpected address length = %d bytes", l)
+			protoAddr := tcpip.ProtocolAddress{Protocol: test.proto, AddressWithPrefix: test.localAddr}
+			if err := s.AddProtocolAddress(nicID, protoAddr); err != nil {
+				t.Fatalf("AddProtocolAddress(%d, %#v): %s", nicID, protoAddr, err)
 			}
 
 			var wq waiter.Queue
-			ep, err := s.NewEndpoint(udp.ProtocolNumber, netproto, &wq)
+			ep, err := s.NewEndpoint(udp.ProtocolNumber, test.proto, &wq)
 			if err != nil {
-				t.Fatalf("NewEndpoint(%d, %d, _): %s", udp.ProtocolNumber, netproto, err)
+				t.Fatalf("NewEndpoint(%d, %d, _): %s", udp.ProtocolNumber, test.proto, err)
 			}
 			defer ep.Close()
 
 			bindAddr := tcpip.FullAddress{Addr: test.bindAddr, Port: localPort}
 			if err := ep.Bind(bindAddr); err != nil {
-				t.Fatalf("ep.Bind(%+v): %s", bindAddr, err)
+				t.Fatalf("ep.Bind(%#v): %s", bindAddr, err)
 			}
 
-			rxUDP(e, test.dstAddr)
+			test.rxUDP(e, test.remoteAddr, test.dstAddr, data)
 			if gotPayload, _, err := ep.Read(nil); test.expectRx {
 				if err != nil {
 					t.Fatalf("Read(nil): %s", err)
@@ -476,7 +518,7 @@ func TestReuseAddrAndBroadcast(t *testing.T) {
 				},
 			}
 			if err := s.AddProtocolAddress(nicID, protoAddr); err != nil {
-				t.Fatalf("AddProtocolAddress(%d, %+v): %s", nicID, protoAddr, err)
+				t.Fatalf("AddProtocolAddress(%d, %#v): %s", nicID, protoAddr, err)
 			}
 
 			s.SetRouteTable([]tcpip.Route{
@@ -516,12 +558,12 @@ func TestReuseAddrAndBroadcast(t *testing.T) {
 					bindAddr := tcpip.FullAddress{Port: localPort}
 					if bindWildcard {
 						if err := ep.Bind(bindAddr); err != nil {
-							t.Fatalf("eps[%d].Bind(%+v): %s", len(eps), bindAddr, err)
+							t.Fatalf("eps[%d].Bind(%#v): %s", len(eps), bindAddr, err)
 						}
 					} else {
 						bindAddr.Addr = test.broadcastAddr
 						if err := ep.Bind(bindAddr); err != nil {
-							t.Fatalf("eps[%d].Bind(%+v): %s", len(eps), bindAddr, err)
+							t.Fatalf("eps[%d].Bind(%#v): %s", len(eps), bindAddr, err)
 						}
 					}
 
@@ -557,3 +599,143 @@ func TestReuseAddrAndBroadcast(t *testing.T) {
 		})
 	}
 }
+
+func TestUDPAddRemoveMembershipSocketOption(t *testing.T) {
+	const (
+		nicID = 1
+	)
+
+	data := []byte{1, 2, 3, 4}
+
+	tests := []struct {
+		name          string
+		proto         tcpip.NetworkProtocolNumber
+		remoteAddr    tcpip.Address
+		localAddr     tcpip.AddressWithPrefix
+		rxUDP         func(*channel.Endpoint, tcpip.Address, tcpip.Address, []byte)
+		multicastAddr tcpip.Address
+	}{
+		{
+			name:          "IPv4 unicast binding to unicast",
+			multicastAddr: "\xe0\x01\x02\x03",
+			proto:         header.IPv4ProtocolNumber,
+			remoteAddr:    remoteIPv4Addr,
+			localAddr:     ipv4Addr,
+			rxUDP:         rxIPv4UDP,
+		},
+		{
+			name:          "IPv6 broadcast-like address binding to wildcard",
+			multicastAddr: "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x02\x03\x04",
+			proto:         header.IPv6ProtocolNumber,
+			remoteAddr:    remoteIPv6Addr,
+			localAddr:     ipv6Addr,
+			rxUDP:         rxIPv6UDP,
+		},
+	}
+
+	subTests := []struct {
+		name           string
+		specifyNICID   bool
+		specifyNICAddr bool
+	}{
+		{
+			name:           "Specify NIC ID and NIC address",
+			specifyNICID:   true,
+			specifyNICAddr: true,
+		},
+		{
+			name:           "Don't specify NIC ID or NIC address",
+			specifyNICID:   false,
+			specifyNICAddr: false,
+		},
+		{
+			name:           "Specify NIC ID but don't specify NIC address",
+			specifyNICID:   true,
+			specifyNICAddr: false,
+		},
+		{
+			name:           "Don't specify NIC ID but specify NIC address",
+			specifyNICID:   false,
+			specifyNICAddr: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			for _, subTest := range subTests {
+				t.Run(subTest.name, func(t *testing.T) {
+					s := stack.New(stack.Options{
+						NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
+						TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
+					})
+					e := channel.New(0, defaultMTU, "")
+					if err := s.CreateNIC(nicID, e); err != nil {
+						t.Fatalf("CreateNIC(%d, _): %s", nicID, err)
+					}
+					protoAddr := tcpip.ProtocolAddress{Protocol: test.proto, AddressWithPrefix: test.localAddr}
+					if err := s.AddProtocolAddress(nicID, protoAddr); err != nil {
+						t.Fatalf("AddProtocolAddress(%d, %#v): %s", nicID, protoAddr, err)
+					}
+
+					// Set the route table so that UDP can find a NIC that is
+					// routable to the multicast address when the NIC isn't specified.
+					if !subTest.specifyNICID && !subTest.specifyNICAddr {
+						s.SetRouteTable([]tcpip.Route{
+							tcpip.Route{
+								Destination: header.IPv6EmptySubnet,
+								NIC:         nicID,
+							},
+							tcpip.Route{
+								Destination: header.IPv4EmptySubnet,
+								NIC:         nicID,
+							},
+						})
+					}
+
+					var wq waiter.Queue
+					ep, err := s.NewEndpoint(udp.ProtocolNumber, test.proto, &wq)
+					if err != nil {
+						t.Fatalf("NewEndpoint(%d, %d, _): %s", udp.ProtocolNumber, test.proto, err)
+					}
+					defer ep.Close()
+
+					bindAddr := tcpip.FullAddress{Port: localPort}
+					if err := ep.Bind(bindAddr); err != nil {
+						t.Fatalf("ep.Bind(%#v): %s", bindAddr, err)
+					}
+
+					memOpt := tcpip.MembershipOption{MulticastAddr: test.multicastAddr}
+					if subTest.specifyNICID {
+						memOpt.NIC = nicID
+					}
+					if subTest.specifyNICAddr {
+						memOpt.InterfaceAddr = test.localAddr.Address
+					}
+
+					// We should receive UDP packets to the group once we join the
+					// multicast group.
+					addOpt := tcpip.AddMembershipOption(memOpt)
+					if err := ep.SetSockOpt(&addOpt); err != nil {
+						t.Fatalf("ep.SetSockOpt(&%#v): %s", addOpt, err)
+					}
+					test.rxUDP(e, test.remoteAddr, test.multicastAddr, data)
+					if gotPayload, _, err := ep.Read(nil); err != nil {
+						t.Fatalf("ep.Read(nil): %s", err)
+					} else if diff := cmp.Diff(buffer.View(data), gotPayload); diff != "" {
+						t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
+					}
+
+					// We should not receive UDP packets to the group once we leave
+					// the multicast group.
+					removeOpt := tcpip.RemoveMembershipOption(memOpt)
+					if err := ep.SetSockOpt(&removeOpt); err != nil {
+						t.Fatalf("ep.SetSockOpt(&%#v): %s", removeOpt, err)
+					}
+					if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock {
+						t.Fatalf("got ep.Read(nil) = (%x, _, %s), want = (nil, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+					}
+				})
+			}
+		})
+	}
+}
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 9b9e4deb0..4e8bd8b04 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -708,14 +708,9 @@ func (e *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 
 		nicID := v.NIC
 
-		// The interface address is considered not-set if it is empty or contains
-		// all-zeros. The former represent the zero-value in golang, the latter the
-		// same in a setsockopt(IP_ADD_MEMBERSHIP, &ip_mreqn) syscall.
-		allZeros := header.IPv4Any
-		if len(v.InterfaceAddr) == 0 || v.InterfaceAddr == allZeros {
+		if v.InterfaceAddr.Unspecified() {
 			if nicID == 0 {
-				r, err := e.stack.FindRoute(0, "", v.MulticastAddr, header.IPv4ProtocolNumber, false /* multicastLoop */)
-				if err == nil {
+				if r, err := e.stack.FindRoute(0, "", v.MulticastAddr, e.NetProto, false /* multicastLoop */); err == nil {
 					nicID = r.NICID()
 					r.Release()
 				}
@@ -748,10 +743,9 @@ func (e *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 		}
 
 		nicID := v.NIC
-		if v.InterfaceAddr == header.IPv4Any {
+		if v.InterfaceAddr.Unspecified() {
 			if nicID == 0 {
-				r, err := e.stack.FindRoute(0, "", v.MulticastAddr, header.IPv4ProtocolNumber, false /* multicastLoop */)
-				if err == nil {
+				if r, err := e.stack.FindRoute(0, "", v.MulticastAddr, e.NetProto, false /* multicastLoop */); err == nil {
 					nicID = r.NICID()
 					r.Release()
 				}