print-mpls.c revision 1.7 
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#include <sys/cdefs.h>
30#ifndef lint
31__RCSID("$NetBSD: print-mpls.c,v 1.7 2017/02/05 04:05:05 spz Exp $");
32#endif
33
34/* \summary: Multi-Protocol Label Switching (MPLS) printer */
35
36#ifdef HAVE_CONFIG_H
37#include "config.h"
38#endif
39
40#include <netdissect-stdinc.h>
41
42#include "netdissect.h"
43#include "extract.h"
44#include "mpls.h"
45
46static const char *mpls_labelname[] = {
47/*0*/	"IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
48	"implicit NULL", "rsvd",
49/*5*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
50/*10*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
51/*15*/	"rsvd",
52};
53
54enum mpls_packet_type {
55	PT_UNKNOWN,
56	PT_IPV4,
57	PT_IPV6,
58	PT_OSI
59};
60
61/*
62 * RFC3032: MPLS label stack encoding
63 */
64void
65mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
66{
67	const u_char *p;
68	uint32_t label_entry;
69	uint16_t label_stack_depth = 0;
70	enum mpls_packet_type pt = PT_UNKNOWN;
71
72	p = bp;
73	ND_PRINT((ndo, "MPLS"));
74	do {
75		ND_TCHECK2(*p, sizeof(label_entry));
76		if (length < sizeof(label_entry)) {
77			ND_PRINT((ndo, "[|MPLS], length %u", length));
78			return;
79		}
80		label_entry = EXTRACT_32BITS(p);
81		ND_PRINT((ndo, "%s(label %u",
82		       (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
83       		       MPLS_LABEL(label_entry)));
84		label_stack_depth++;
85		if (ndo->ndo_vflag &&
86		    MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
87			ND_PRINT((ndo, " (%s)", mpls_labelname[MPLS_LABEL(label_entry)]));
88		ND_PRINT((ndo, ", exp %u", MPLS_EXP(label_entry)));
89		if (MPLS_STACK(label_entry))
90			ND_PRINT((ndo, ", [S]"));
91		ND_PRINT((ndo, ", ttl %u)", MPLS_TTL(label_entry)));
92
93		p += sizeof(label_entry);
94		length -= sizeof(label_entry);
95	} while (!MPLS_STACK(label_entry));
96
97	/*
98	 * Try to figure out the packet type.
99	 */
100	switch (MPLS_LABEL(label_entry)) {
101
102	case 0:	/* IPv4 explicit NULL label */
103	case 3:	/* IPv4 implicit NULL label */
104		pt = PT_IPV4;
105		break;
106
107	case 2:	/* IPv6 explicit NULL label */
108		pt = PT_IPV6;
109		break;
110
111	default:
112		/*
113		 * Generally there's no indication of protocol in MPLS label
114		 * encoding.
115		 *
116		 * However, draft-hsmit-isis-aal5mux-00.txt describes a
117		 * technique for encapsulating IS-IS and IP traffic on the
118		 * same ATM virtual circuit; you look at the first payload
119		 * byte to determine the network layer protocol, based on
120		 * the fact that
121		 *
122		 *	1) the first byte of an IP header is 0x45-0x4f
123		 *	   for IPv4 and 0x60-0x6f for IPv6;
124		 *
125		 *	2) the first byte of an OSI CLNP packet is 0x81,
126		 *	   the first byte of an OSI ES-IS packet is 0x82,
127		 *	   and the first byte of an OSI IS-IS packet is
128		 *	   0x83;
129		 *
130		 * so the network layer protocol can be inferred from the
131		 * first byte of the packet, if the protocol is one of the
132		 * ones listed above.
133		 *
134		 * Cisco sends control-plane traffic MPLS-encapsulated in
135		 * this fashion.
136		 */
137		ND_TCHECK(*p);
138		if (length < 1) {
139			/* nothing to print */
140			return;
141		}
142		switch(*p) {
143
144		case 0x45:
145		case 0x46:
146		case 0x47:
147		case 0x48:
148		case 0x49:
149		case 0x4a:
150		case 0x4b:
151		case 0x4c:
152		case 0x4d:
153		case 0x4e:
154		case 0x4f:
155			pt = PT_IPV4;
156			break;
157
158		case 0x60:
159		case 0x61:
160		case 0x62:
161		case 0x63:
162		case 0x64:
163		case 0x65:
164		case 0x66:
165		case 0x67:
166		case 0x68:
167		case 0x69:
168		case 0x6a:
169		case 0x6b:
170		case 0x6c:
171		case 0x6d:
172		case 0x6e:
173		case 0x6f:
174			pt = PT_IPV6;
175			break;
176
177		case 0x81:
178		case 0x82:
179		case 0x83:
180			pt = PT_OSI;
181			break;
182
183		default:
184			/* ok bail out - we did not figure out what it is*/
185			break;
186		}
187	}
188
189	/*
190	 * Print the payload.
191	 */
192	if (pt == PT_UNKNOWN) {
193		if (!ndo->ndo_suppress_default_print)
194			ND_DEFAULTPRINT(p, length);
195		return;
196	}
197	ND_PRINT((ndo, ndo->ndo_vflag ? "\n\t" : " "));
198	switch (pt) {
199
200	case PT_IPV4:
201		ip_print(ndo, p, length);
202		break;
203
204	case PT_IPV6:
205		ip6_print(ndo, p, length);
206		break;
207
208	case PT_OSI:
209		isoclns_print(ndo, p, length, length);
210		break;
211
212	default:
213		break;
214	}
215	return;
216
217trunc:
218	ND_PRINT((ndo, "[|MPLS]"));
219}
220
221
222/*
223 * Local Variables:
224 * c-style: whitesmith
225 * c-basic-offset: 8
226 * End:
227 */
228