2 files changed, 51 insertions, 0 deletions
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 0e944712f..9ca39ce40 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -328,6 +328,12 @@ type ControlMessages struct {
 
 	// Tclass is the IPv6 traffic class of the associated packet.
 	TClass int32
+
+	// HasIPPacketInfo indicates whether PacketInfo is set.
+	HasIPPacketInfo bool
+
+	// PacketInfo holds interface and address data on an incoming packet.
+	PacketInfo IPPacketInfo
 }
 
 // Endpoint is the interface implemented by transport protocols (e.g., tcp, udp)
@@ -503,6 +509,11 @@ const (
 	// V6OnlyOption is used by {G,S}etSockOptBool to specify whether an IPv6
 	// socket is to be restricted to sending and receiving IPv6 packets only.
 	V6OnlyOption
+
+	// ReceiveIPPacketInfoOption is used by {G,S}etSockOptBool to specify
+	// if more inforamtion is provided with incoming packets such
+	// as interface index and address.
+	ReceiveIPPacketInfoOption
 )
 
 // SockOptInt represents socket options which values have the int type.
@@ -685,6 +696,20 @@ type IPv4TOSOption uint8
 // for all subsequent outgoing IPv6 packets from the endpoint.
 type IPv6TrafficClassOption uint8
 
+// IPPacketInfo is the message struture for IP_PKTINFO.
+//
+// +stateify savable
+type IPPacketInfo struct {
+	// NIC is the ID of the NIC to be used.
+	NIC NICID
+
+	// LocalAddr is the local address.
+	LocalAddr Address
+
+	// DestinationAddr is the destination address.
+	DestinationAddr Address
+}
+
 // Route is a row in the routing table. It specifies through which NIC (and
 // gateway) sets of packets should be routed. A row is considered viable if the
 // masked target address matches the destination address in the row.
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index c9cbed8f4..3fe91cac2 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -29,6 +29,7 @@ import (
 type udpPacket struct {
 	udpPacketEntry
 	senderAddress tcpip.FullAddress
+	packetInfo    tcpip.IPPacketInfo
 	data          buffer.VectorisedView `state:".(buffer.VectorisedView)"`
 	timestamp     int64
 	tos           uint8
@@ -118,6 +119,9 @@ type endpoint struct {
 	// as ancillary data to ControlMessages on Read.
 	receiveTOS bool
 
+	// receiveIPPacketInfo determines if the packet info is returned by Read.
+	receiveIPPacketInfo bool
+
 	// shutdownFlags represent the current shutdown state of the endpoint.
 	shutdownFlags tcpip.ShutdownFlags
 
@@ -254,11 +258,17 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 	}
 	e.mu.RLock()
 	receiveTOS := e.receiveTOS
+	receiveIPPacketInfo := e.receiveIPPacketInfo
 	e.mu.RUnlock()
 	if receiveTOS {
 		cm.HasTOS = true
 		cm.TOS = p.tos
 	}
+
+	if receiveIPPacketInfo {
+		cm.HasIPPacketInfo = true
+		cm.PacketInfo = p.packetInfo
+	}
 	return p.data.ToView(), cm, nil
 }
 
@@ -495,6 +505,13 @@ func (e *endpoint) SetSockOptBool(opt tcpip.SockOptBool, v bool) *tcpip.Error {
 		}
 
 		e.v6only = v
+		return nil
+
+	case tcpip.ReceiveIPPacketInfoOption:
+		e.mu.Lock()
+		e.receiveIPPacketInfo = v
+		e.mu.Unlock()
+		return nil
 	}
 
 	return nil
@@ -703,6 +720,12 @@ func (e *endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
 		e.mu.RUnlock()
 
 		return v, nil
+
+	case tcpip.ReceiveIPPacketInfoOption:
+		e.mu.RLock()
+		v := e.receiveIPPacketInfo
+		e.mu.RUnlock()
+		return v, nil
 	}
 
 	return false, tcpip.ErrUnknownProtocolOption
@@ -1247,6 +1270,9 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, pk
 	switch r.NetProto {
 	case header.IPv4ProtocolNumber:
 		packet.tos, _ = header.IPv4(pkt.NetworkHeader).TOS()
+		packet.packetInfo.LocalAddr = r.LocalAddress
+		packet.packetInfo.DestinationAddr = r.RemoteAddress
+		packet.packetInfo.NIC = r.NICID()
 	}
 
 	packet.timestamp = e.stack.NowNanoseconds()