Add support for ethernet IP protocol

The SRv6 network programming defines a new IP protocol number [1].

The new protocol number is used in the Next Header field of an IPv6 header
or any extension header indicates that the payload is an Ethernet.

IANA has assigned 143 as the protocol number of ethernet [2].

The SRv6 packet has the following format:
IPv6 HDR + SRH + Ethernet HDR + IPv4/IPv6 packet

This patch allows TCPDUMP to dissect such SRv6 packets.

[1] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-16#section-9.1
[2] https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml

Signed-off-by: Ahmed Abdelsalam <ahabdels@gmail.com>

6 files changed, 16 insertions, 0 deletions

diff --git a/ipproto.c b/ipproto.c
index 58ceeeba..a3b0714a 100644
--- a/ipproto.c
+++ b/ipproto.c
@@ -50,6 +50,7 @@ const struct tok ipproto_values[] = {
     { IPPROTO_PGM, "PGM" },
     { IPPROTO_SCTP, "SCTP" },
     { IPPROTO_MOBILITY, "Mobility" },
+    { IPPROTO_ETHERNET, "Ethernet" },
     { 0, NULL }
 };
 
diff --git a/ipproto.h b/ipproto.h
index 845cf008..baec4bdc 100644
--- a/ipproto.h
+++ b/ipproto.h
@@ -140,3 +140,6 @@ extern const char *netdb_protoname (const uint8_t);
 #ifndef IPPROTO_MOBILITY
 #define IPPROTO_MOBILITY	135
 #endif
+#ifndef IPPROTO_ETHERNET
+#define IPPROTO_ETHERNET	143 /* TEMPORARY - registered 2020-01-31, expires 2021-01-31 */
+#endif
diff --git a/print-ip-demux.c b/print-ip-demux.c
index 7df0f709..8b53187c 100644
--- a/print-ip-demux.c
+++ b/print-ip-demux.c
@@ -208,6 +208,16 @@ again:
 		pgm_print(ndo, bp, length, iph);
 		break;
 
+	case IPPROTO_ETHERNET:
+		if (ver == 6)
+			ether_print(ndo, bp, length, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
+		else {
+			ND_PRINT("[%s requires IPv6]",
+				 tok2str(ipproto_values,"unknown",nh));
+			nd_print_invalid(ndo);
+		}
+		break;
+
 	case IPPROTO_NONE:
 		ND_PRINT("no next header");
 		break;
diff --git a/tests/TESTLIST b/tests/TESTLIST
index 90fc31d2..8da36269 100644
--- a/tests/TESTLIST
+++ b/tests/TESTLIST
@@ -285,6 +285,7 @@ ipv6-bad-version	ipv6-bad-version.pcap 	ipv6-bad-version.out
 ipv6-routing-header	ipv6-routing-header.pcap	ipv6-routing-header.out -v
 ipv6-srh-ext-header	ipv6-srh-ext-header.pcap 	ipv6-srh-ext-header.out -v
 ipv6-srh-insert-cksum	ipv6-srh-insert-cksum.pcap	ipv6-srh-insert-cksum.out -v
+ipv6-srh-ipproto-ether	ipv6-srh-ipproto-ether.pcap	ipv6-srh-ipproto-ether.out -ev
 # Loopback/CTP test case
 loopback	loopback.pcap		loopback.out
 
diff --git a/tests/ipv6-srh-ipproto-ether.out b/tests/ipv6-srh-ipproto-ether.out
new file mode 100644
index 00000000..96a99bc7
--- /dev/null
+++ b/tests/ipv6-srh-ipproto-ether.out
@@ -0,0 +1 @@
+    1  15:07:04.802036 be:f5:06:09:44:74 > d6:67:19:4e:0f:4f, ethertype IPv6 (0x86dd), length 196: (flowlabel 0xde027, hlim 63, next-header Routing (43) payload length: 142) a::1 > c::2: srcrt (len=2, type=4, segleft=0, last-entry=0, flags=0x0, tag=0, [0]c::2) ae:64:42:3b:5b:9a > 1e:1d:df:cd:54:7a, ethertype IPv6 (0x86dd), length 118: (flowlabel 0xde027, hlim 64, next-header ICMPv6 (58) payload length: 64) a::2 > e::2: [icmp6 sum ok] ICMP6, echo request, id 18516, seq 1339
diff --git a/tests/ipv6-srh-ipproto-ether.pcap b/tests/ipv6-srh-ipproto-ether.pcap
new file mode 100644
index 00000000..30181e4d
--- /dev/null
+++ b/tests/ipv6-srh-ipproto-ether.pcap