From 99decaadd6da0df2d8ec70ddea9d754c9d71a584 Mon Sep 17 00:00:00 2001 From: Julian Elischer Date: Wed, 23 Sep 2020 02:26:50 -0700 Subject: Extract ICMP error sender from UDP Store transport protocol number on packet buffers for use in ICMP error generation. Updates #2211. PiperOrigin-RevId: 333252762 --- pkg/tcpip/stack/nic.go | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) (limited to 'pkg/tcpip/stack/nic.go') diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go index be274773c..06d70dd1c 100644 --- a/pkg/tcpip/stack/nic.go +++ b/pkg/tcpip/stack/nic.go @@ -1242,9 +1242,9 @@ func (n *NIC) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcp local = n.linkEP.LinkAddress() } - // Are any packet sockets listening for this network protocol? + // Are any packet type sockets listening for this network protocol? packetEPs := n.mu.packetEPs[protocol] - // Add any other packet sockets that maybe listening for all protocols. + // Add any other packet type sockets that may be listening for all protocols. packetEPs = append(packetEPs, n.mu.packetEPs[header.EthernetProtocolAll]...) n.mu.RUnlock() for _, ep := range packetEPs { @@ -1265,6 +1265,7 @@ func (n *NIC) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcp return } if hasTransportHdr { + pkt.TransportProtocolNumber = transProtoNum // Parse the transport header if present. if state, ok := n.stack.transportProtocols[transProtoNum]; ok { state.proto.Parse(pkt) @@ -1453,10 +1454,28 @@ func (n *NIC) DeliverTransportPacket(r *Route, protocol tcpip.TransportProtocolN } } - // We could not find an appropriate destination for this packet, so - // deliver it to the global handler. - if !transProto.HandleUnknownDestinationPacket(r, id, pkt) { + // We could not find an appropriate destination for this packet so + // give the protocol specific error handler a chance to handle it. + // If it doesn't handle it then we should do so. + switch transProto.HandleUnknownDestinationPacket(r, id, pkt) { + case UnknownDestinationPacketMalformed: n.stack.stats.MalformedRcvdPackets.Increment() + case UnknownDestinationPacketUnhandled: + // As per RFC: 1122 Section 3.2.2.1 A host SHOULD generate Destination + // Unreachable messages with code: + // 3 (Port Unreachable), when the designated transport protocol + // (e.g., UDP) is unable to demultiplex the datagram but has no + // protocol mechanism to inform the sender. + np, ok := n.stack.networkProtocols[r.NetProto] + if !ok { + // For this to happen stack.makeRoute() must have been called with the + // incorrect protocol number. Since we have successfully completed + // network layer processing this should be impossible. + panic(fmt.Sprintf("expected stack to have a NetworkProtocol for proto = %d", r.NetProto)) + } + + _ = np.ReturnError(r, &tcpip.ICMPReasonPortUnreachable{}, pkt) + case UnknownDestinationPacketHandled: } } -- cgit v1.2.3