Add support for IP_RECVORIGDSTADDR IP option.

Fixes #5004

PiperOrigin-RevId: 346643745

2 files changed, 101 insertions, 4 deletions

diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index ee1bb29f8..04596183e 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -30,10 +30,11 @@ import (
 // +stateify savable
 type udpPacket struct {
 	udpPacketEntry
-	senderAddress tcpip.FullAddress
-	packetInfo    tcpip.IPPacketInfo
-	data          buffer.VectorisedView `state:".(buffer.VectorisedView)"`
-	timestamp     int64
+	senderAddress      tcpip.FullAddress
+	destinationAddress tcpip.FullAddress
+	packetInfo         tcpip.IPPacketInfo
+	data               buffer.VectorisedView `state:".(buffer.VectorisedView)"`
+	timestamp          int64
 	// tos stores either the receiveTOS or receiveTClass value.
 	tos uint8
 }
@@ -323,6 +324,10 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 		cm.HasIPPacketInfo = true
 		cm.PacketInfo = p.packetInfo
 	}
+	if e.ops.GetReceiveOriginalDstAddress() {
+		cm.HasOriginalDstAddress = true
+		cm.OriginalDstAddress = p.destinationAddress
+	}
 	return p.data.ToView(), cm, nil
 }
 
@@ -1314,6 +1319,11 @@ func (e *endpoint) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketB
 			Addr: id.RemoteAddress,
 			Port: hdr.SourcePort(),
 		},
+		destinationAddress: tcpip.FullAddress{
+			NIC:  pkt.NICID,
+			Addr: id.LocalAddress,
+			Port: header.UDP(hdr).DestinationPort(),
+		},
 	}
 	packet.data = pkt.Data
 	e.rcvList.PushBack(packet)
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index b0b9b2773..cca865b34 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -1428,6 +1428,93 @@ func TestReadIPPacketInfo(t *testing.T) {
 	}
 }
 
+func TestReadRecvOriginalDstAddr(t *testing.T) {
+	tests := []struct {
+		name                    string
+		proto                   tcpip.NetworkProtocolNumber
+		flow                    testFlow
+		expectedOriginalDstAddr tcpip.FullAddress
+	}{
+		{
+			name:                    "IPv4 unicast",
+			proto:                   header.IPv4ProtocolNumber,
+			flow:                    unicastV4,
+			expectedOriginalDstAddr: tcpip.FullAddress{1, stackAddr, stackPort},
+		},
+		{
+			name:  "IPv4 multicast",
+			proto: header.IPv4ProtocolNumber,
+			flow:  multicastV4,
+			// This should actually be a unicast address assigned to the interface.
+			//
+			// TODO(gvisor.dev/issue/3556): This check is validating incorrect
+			// behaviour. We still include the test so that once the bug is
+			// resolved, this test will start to fail and the individual tasked
+			// with fixing this bug knows to also fix this test :).
+			expectedOriginalDstAddr: tcpip.FullAddress{1, multicastAddr, stackPort},
+		},
+		{
+			name:  "IPv4 broadcast",
+			proto: header.IPv4ProtocolNumber,
+			flow:  broadcast,
+			// This should actually be a unicast address assigned to the interface.
+			//
+			// TODO(gvisor.dev/issue/3556): This check is validating incorrect
+			// behaviour. We still include the test so that once the bug is
+			// resolved, this test will start to fail and the individual tasked
+			// with fixing this bug knows to also fix this test :).
+			expectedOriginalDstAddr: tcpip.FullAddress{1, broadcastAddr, stackPort},
+		},
+		{
+			name:                    "IPv6 unicast",
+			proto:                   header.IPv6ProtocolNumber,
+			flow:                    unicastV6,
+			expectedOriginalDstAddr: tcpip.FullAddress{1, stackV6Addr, stackPort},
+		},
+		{
+			name:  "IPv6 multicast",
+			proto: header.IPv6ProtocolNumber,
+			flow:  multicastV6,
+			// This should actually be a unicast address assigned to the interface.
+			//
+			// TODO(gvisor.dev/issue/3556): This check is validating incorrect
+			// behaviour. We still include the test so that once the bug is
+			// resolved, this test will start to fail and the individual tasked
+			// with fixing this bug knows to also fix this test :).
+			expectedOriginalDstAddr: tcpip.FullAddress{1, multicastV6Addr, stackPort},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			c := newDualTestContext(t, defaultMTU)
+			defer c.cleanup()
+
+			c.createEndpoint(test.proto)
+
+			bindAddr := tcpip.FullAddress{Port: stackPort}
+			if err := c.ep.Bind(bindAddr); err != nil {
+				t.Fatalf("Bind(%+v): %s", bindAddr, err)
+			}
+
+			if test.flow.isMulticast() {
+				ifoptSet := tcpip.AddMembershipOption{NIC: 1, MulticastAddr: test.flow.getMcastAddr()}
+				if err := c.ep.SetSockOpt(&ifoptSet); err != nil {
+					c.t.Fatalf("SetSockOpt(&%#v): %s:", ifoptSet, err)
+				}
+			}
+
+			c.ep.SocketOptions().SetReceiveOriginalDstAddress(true)
+
+			testRead(c, test.flow, checker.ReceiveOriginalDstAddr(test.expectedOriginalDstAddr))
+
+			if got := c.s.Stats().UDP.PacketsReceived.Value(); got != 1 {
+				t.Fatalf("Read did not increment PacketsReceived: got = %d, want = 1", got)
+			}
+		})
+	}
+}
+
 func TestWriteIncrementsPacketsSent(t *testing.T) {
 	c := newDualTestContext(t, defaultMTU)
 	defer c.cleanup()