ipv6: ICMP support

This CL does NDP link-address discovery for IPv6.

It includes several small changes necessary to get linux to talk to
this implementation. In particular, a hop limit of 255 is necessary
for ICMPv6.

PiperOrigin-RevId: 211103930
Change-Id: If25370ab84c6b1decfb15de917f3b0020f2c4e0e

2 files changed, 37 insertions, 0 deletions

diff --git a/pkg/tcpip/link/channel/channel.go b/pkg/tcpip/link/channel/channel.go
index 9d69f1d45..dd3fe7c87 100644
--- a/pkg/tcpip/link/channel/channel.go
+++ b/pkg/tcpip/link/channel/channel.go
@@ -71,6 +71,12 @@ func (e *Endpoint) Inject(protocol tcpip.NetworkProtocolNumber, vv *buffer.Vecto
 	e.dispatcher.DeliverNetworkPacket(e, "", protocol, &uu)
 }
 
+// InjectLinkAddr injects an inbound packet with a remote link address.
+func (e *Endpoint) InjectLinkAddr(protocol tcpip.NetworkProtocolNumber, remoteLinkAddr tcpip.LinkAddress, vv *buffer.VectorisedView) {
+	uu := vv.Clone(nil)
+	e.dispatcher.DeliverNetworkPacket(e, remoteLinkAddr, protocol, &uu)
+}
+
 // Attach saves the stack network-layer dispatcher for use later when packets
 // are injected.
 func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
diff --git a/pkg/tcpip/link/sniffer/sniffer.go b/pkg/tcpip/link/sniffer/sniffer.go
index 414a7edb4..1e302f557 100644
--- a/pkg/tcpip/link/sniffer/sniffer.go
+++ b/pkg/tcpip/link/sniffer/sniffer.go
@@ -303,6 +303,37 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, b, plb []byt
 		log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
 		return
 
+	case header.ICMPv6ProtocolNumber:
+		transName = "icmp"
+		icmp := header.ICMPv6(b)
+		icmpType := "unknown"
+		switch icmp.Type() {
+		case header.ICMPv6DstUnreachable:
+			icmpType = "destination unreachable"
+		case header.ICMPv6PacketTooBig:
+			icmpType = "packet too big"
+		case header.ICMPv6TimeExceeded:
+			icmpType = "time exceeded"
+		case header.ICMPv6ParamProblem:
+			icmpType = "param problem"
+		case header.ICMPv6EchoRequest:
+			icmpType = "echo request"
+		case header.ICMPv6EchoReply:
+			icmpType = "echo reply"
+		case header.ICMPv6RouterSolicit:
+			icmpType = "router solicit"
+		case header.ICMPv6RouterAdvert:
+			icmpType = "router advert"
+		case header.ICMPv6NeighborSolicit:
+			icmpType = "neighbor solicit"
+		case header.ICMPv6NeighborAdvert:
+			icmpType = "neighbor advert"
+		case header.ICMPv6RedirectMsg:
+			icmpType = "redirect message"
+		}
+		log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
+		return
+
 	case header.UDPProtocolNumber:
 		transName = "udp"
 		udp := header.UDP(b)