teach tcpdump some more things about gre.

gre can be encapsulated in ipv6.
gre can encapsulate ipv6, mpls, and ethernet.
nvgre is based on gre, so if the header could be nvgre print the
vsid and flow id as well as the key.

ok stsp@

2 files changed, 75 insertions, 30 deletions

diff --git a/usr.sbin/tcpdump/print-gre.c b/usr.sbin/tcpdump/print-gre.c
index 726d8be1b24..09dd3651e50 100644
--- a/usr.sbin/tcpdump/print-gre.c
+++ b/usr.sbin/tcpdump/print-gre.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: print-gre.c,v 1.11 2015/11/05 11:55:21 jca Exp $	*/
+/*	$OpenBSD: print-gre.c,v 1.12 2016/12/13 06:40:21 dlg Exp $	*/
 
 /*
  * Copyright (c) 2002 Jason L. Wright (jason@thought.net)
@@ -39,6 +39,8 @@
 #include <netinet/ip.h>
 #include <arpa/inet.h>
 
+#include <net/ethertypes.h>
+
 #include <stdio.h>
 #include <string.h>
 
@@ -55,13 +57,15 @@
 #define	GRE_AP		0x0080		/* acknowledgment# present */
 #define	GRE_VERS	0x0007		/* protocol version */
 
-#define	GREPROTO_IP	0x0800		/* IP */
-#define	GREPROTO_PPP	0x880b		/* PPTP */
-
 /* source route entry types */
 #define	GRESRE_IP	0x0800		/* IP */
 #define	GRESRE_ASN	0xfffe		/* ASN */
 
+#define NVGRE_VSID_MASK		0xffffff00U
+#define NVGRE_VSID_SHIFT	8
+#define NVGRE_FLOWID_MASK	0x000000ffU
+#define NVGRE_FLOWID_SHIFT	0
+
 void gre_print_0(const u_char *, u_int);
 void gre_print_1(const u_char *, u_int);
 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
@@ -82,14 +86,17 @@ gre_print(const u_char *bp, u_int length)
 	}
 	vers = EXTRACT_16BITS(bp) & GRE_VERS;
 
-	if (vers == 0)
+	switch (vers) {
+	case 0:
 		gre_print_0(bp, len);
-	else if (vers == 1)
+		break;
+	case 1:
 		gre_print_1(bp, len);
-	else
+		break;
+	default:
 		printf("gre-unknown-version=%u", vers);
-	return;
-
+		break;
+	}
 }
 
 void
@@ -114,6 +121,8 @@ gre_print_0(const u_char *bp, u_int length)
 	if (len < 2)
 		goto trunc;
 	prot = EXTRACT_16BITS(bp);
+	printf("%s", etherproto_string(prot));
+
 	len -= 2;
 	bp += 2;
 
@@ -121,21 +130,32 @@ gre_print_0(const u_char *bp, u_int length)
 		if (len < 2)
 			goto trunc;
 		if (vflag)
-			printf("sum 0x%x ", EXTRACT_16BITS(bp));
+			printf(" sum 0x%x", EXTRACT_16BITS(bp));
 		bp += 2;
 		len -= 2;
 
 		if (len < 2)
 			goto trunc;
-		printf("off 0x%x ", EXTRACT_16BITS(bp));
+		printf(" off 0x%x", EXTRACT_16BITS(bp));
 		bp += 2;
 		len -= 2;
 	}
 
 	if (flags & GRE_KP) {
+		uint32_t key, vsid;
+
 		if (len < 4)
 			goto trunc;
-		printf("key=0x%x ", EXTRACT_32BITS(bp));
+		key = EXTRACT_32BITS(bp);
+
+		/* maybe NVGRE? */
+		if (flags == (GRE_KP | 0) && prot == ETHERTYPE_TRANSETHER) {
+			vsid = (key & NVGRE_VSID_MASK) >> NVGRE_VSID_SHIFT;
+			printf(" NVGRE vsid=%u (0x%x)+flowid=0x%02x /",
+			    vsid, vsid,
+			    (key & NVGRE_FLOWID_MASK) >> NVGRE_FLOWID_SHIFT);
+		}
+		printf(" key=%u (0x%x)", key, key);
 		bp += 4;
 		len -= 4;
 	}
@@ -143,7 +163,7 @@ gre_print_0(const u_char *bp, u_int length)
 	if (flags & GRE_SP) {
 		if (len < 4)
 			goto trunc;
-		printf("seq %u ", EXTRACT_32BITS(bp));
+		printf(" seq %u", EXTRACT_32BITS(bp));
 		bp += 4;
 		len -= 4;
 	}
@@ -174,10 +194,21 @@ gre_print_0(const u_char *bp, u_int length)
 		}
 	}
 
+	printf(": ");
+
 	switch (prot) {
-	case GREPROTO_IP:
+	case ETHERTYPE_IP:
 		ip_print(bp, len);
 		break;
+	case ETHERTYPE_IPV6:
+		ip6_print(bp, len);
+		break;
+	case ETHERTYPE_MPLS:
+		mpls_print(bp, len);
+		break;
+	case ETHERTYPE_TRANSETHER:
+		ether_print(bp, len);
+		break;
 	default:
 		printf("gre-proto-0x%x", prot);
 	}
@@ -198,7 +229,7 @@ gre_print_1(const u_char *bp, u_int length)
 	bp += 2;
 
 	if (vflag) {
-		printf("[%s%s%s%s%s%s] ",
+		printf("[%s%s%s%s%s%s]",
 		    (flags & GRE_CP) ? "C" : "",
 		    (flags & GRE_RP) ? "R" : "",
 		    (flags & GRE_KP) ? "K" : "",
@@ -214,19 +245,19 @@ gre_print_1(const u_char *bp, u_int length)
 	bp += 2;
 
 	if (flags & GRE_CP) {
-		printf("cpset!");
+		printf(" cpset!");
 		return;
 	}
 	if (flags & GRE_RP) {
-		printf("rpset!");
+		printf(" rpset!");
 		return;
 	}
 	if ((flags & GRE_KP) == 0) {
-		printf("kpunset!");
+		printf(" kpunset!");
 		return;
 	}
 	if (flags & GRE_sP) {
-		printf("spset!");
+		printf(" spset!");
 		return;
 	}
 
@@ -236,7 +267,7 @@ gre_print_1(const u_char *bp, u_int length)
 		if (len < 4)
 			goto trunc;
 		k = EXTRACT_32BITS(bp);
-		printf("call %d ", k & 0xffff);
+		printf(" call %d", k & 0xffff);
 		len -= 4;
 		bp += 4;
 	}
@@ -244,7 +275,7 @@ gre_print_1(const u_char *bp, u_int length)
 	if (flags & GRE_SP) {
 		if (len < 4)
 			goto trunc;
-		printf("seq %u ", EXTRACT_32BITS(bp));
+		printf(" seq %u", EXTRACT_32BITS(bp));
 		bp += 4;
 		len -= 4;
 	}
@@ -252,18 +283,20 @@ gre_print_1(const u_char *bp, u_int length)
 	if (flags & GRE_AP) {
 		if (len < 4)
 			goto trunc;
-		printf("ack %u ", EXTRACT_32BITS(bp));
+		printf(" ack %u", EXTRACT_32BITS(bp));
 		bp += 4;
 		len -= 4;
 	}
 
 	if ((flags & GRE_SP) == 0) {
-		printf("no-payload");
+		printf(" no-payload");
 		return;
 	}
 
+	printf(": ");
+
 	switch (prot) {
-	case GREPROTO_PPP:
+	case ETHERTYPE_PPP:
 		printf("gre-ppp-payload");
 		break;
 	default:
@@ -282,17 +315,17 @@ gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 {
 	switch (af) {
 	case GRESRE_IP:
-		printf("(rtaf=ip");
+		printf(" (rtaf=ip");
 		gre_sre_ip_print(sreoff, srelen, bp, len);
-		printf(") ");
+		printf(")");
 		break;
 	case GRESRE_ASN:
-		printf("(rtaf=asn");
+		printf(" (rtaf=asn");
 		gre_sre_asn_print(sreoff, srelen, bp, len);
-		printf(") ");
+		printf(")");
 		break;
 	default:
-		printf("(rtaf=0x%x) ", af);
+		printf(" (rtaf=0x%x)", af);
 	}
 }
 void
diff --git a/usr.sbin/tcpdump/print-ip6.c b/usr.sbin/tcpdump/print-ip6.c
index 0f4b0efc0ef..2a13577433f 100644
--- a/usr.sbin/tcpdump/print-ip6.c
+++ b/usr.sbin/tcpdump/print-ip6.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: print-ip6.c,v 1.23 2015/11/16 00:16:39 mmcc Exp $	*/
+/*	$OpenBSD: print-ip6.c,v 1.24 2016/12/13 06:40:21 dlg Exp $	*/
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
@@ -184,6 +184,18 @@ ip6_print(const u_char *bp, u_int length)
 			if (! vflag)
 				printf(" (encap)");
 			goto end;
+
+#ifndef IPPROTO_GRE
+#define IPPROTO_GRE 47
+#endif
+		case IPPROTO_GRE:
+			gre_print(cp, len);
+			if (! vflag) {
+				printf(" (gre encap)");
+				goto out;
+			}
+			goto end;
+
 		case IPPROTO_NONE:
 			(void)printf("no next header");
 			goto end;