1/*
2 * Copyright (C) 2001 WIDE Project.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the project nor the names of its contributors
13 *    may be used to endorse or promote products derived from this software
14 *    without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29/* \summary: Multi-Protocol Label Switching (MPLS) printer */
30
31#ifdef HAVE_CONFIG_H
32#include <config.h>
33#endif
34
35#include "netdissect-stdinc.h"
36
37#define ND_LONGJMP_FROM_TCHECK
38#include "netdissect.h"
39#include "extract.h"
40#include "mpls.h"
41
42static const char *mpls_labelname[] = {
43/*0*/	"IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
44	"implicit NULL", "rsvd",
45/*5*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
46/*10*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
47/*15*/	"rsvd",
48};
49
50enum mpls_packet_type {
51	PT_UNKNOWN,
52	PT_IPV4,
53	PT_IPV6,
54	PT_OSI
55};
56
57/*
58 * RFC3032: MPLS label stack encoding
59 */
60void
61mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
62{
63	const u_char *p;
64	uint32_t label_entry;
65	uint16_t label_stack_depth = 0;
66	uint8_t first;
67	enum mpls_packet_type pt = PT_UNKNOWN;
68
69	ndo->ndo_protocol = "mpls";
70	p = bp;
71	nd_print_protocol_caps(ndo);
72	do {
73		if (length < sizeof(label_entry))
74			goto invalid;
75		label_entry = GET_BE_U_4(p);
76		ND_PRINT("%s(label %u",
77		       (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
78			MPLS_LABEL(label_entry));
79		label_stack_depth++;
80		if (ndo->ndo_vflag &&
81		    MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
82			ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
83		ND_PRINT(", tc %u", MPLS_TC(label_entry));
84		if (MPLS_STACK(label_entry))
85			ND_PRINT(", [S]");
86		ND_PRINT(", ttl %u)", MPLS_TTL(label_entry));
87
88		p += sizeof(label_entry);
89		length -= sizeof(label_entry);
90	} while (!MPLS_STACK(label_entry));
91
92	/*
93	 * Try to figure out the packet type.
94	 */
95	switch (MPLS_LABEL(label_entry)) {
96
97	case 0:	/* IPv4 explicit NULL label */
98	case 3:	/* IPv4 implicit NULL label */
99		pt = PT_IPV4;
100		break;
101
102	case 2:	/* IPv6 explicit NULL label */
103		pt = PT_IPV6;
104		break;
105
106	default:
107		/*
108		 * Generally there's no indication of protocol in MPLS label
109		 * encoding.
110		 *
111		 * However, draft-hsmit-isis-aal5mux-00.txt describes a
112		 * technique for encapsulating IS-IS and IP traffic on the
113		 * same ATM virtual circuit; you look at the first payload
114		 * byte to determine the network layer protocol, based on
115		 * the fact that
116		 *
117		 *	1) the first byte of an IP header is 0x45-0x4f
118		 *	   for IPv4 and 0x60-0x6f for IPv6;
119		 *
120		 *	2) the first byte of an OSI CLNP packet is 0x81,
121		 *	   the first byte of an OSI ES-IS packet is 0x82,
122		 *	   and the first byte of an OSI IS-IS packet is
123		 *	   0x83;
124		 *
125		 * so the network layer protocol can be inferred from the
126		 * first byte of the packet, if the protocol is one of the
127		 * ones listed above.
128		 *
129		 * Cisco sends control-plane traffic MPLS-encapsulated in
130		 * this fashion.
131		 */
132		if (length < 1) {
133			/* nothing to print */
134			return;
135		}
136		first = GET_U_1(p);
137		pt =
138			(first >= 0x45 && first <= 0x4f) ? PT_IPV4 :
139			(first >= 0x60 && first <= 0x6f) ? PT_IPV6 :
140			(first >= 0x81 && first <= 0x83) ? PT_OSI :
141			/* ok bail out - we did not figure out what it is*/
142			PT_UNKNOWN;
143	}
144
145	/*
146	 * Print the payload.
147	 */
148	switch (pt) {
149	case PT_UNKNOWN:
150		if (!ndo->ndo_suppress_default_print)
151			ND_DEFAULTPRINT(p, length);
152		break;
153
154	case PT_IPV4:
155		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
156		ip_print(ndo, p, length);
157		break;
158
159	case PT_IPV6:
160		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
161		ip6_print(ndo, p, length);
162		break;
163
164	case PT_OSI:
165		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
166		isoclns_print(ndo, p, length);
167		break;
168	}
169	return;
170
171invalid:
172	nd_print_invalid(ndo);
173	ND_TCHECK_LEN(p, length);
174}
175