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 1.9 2023/08/17 20:19:40 christos 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#define ND_LONGJMP_FROM_TCHECK
43#include "netdissect.h"
44#include "extract.h"
45#include "mpls.h"
46
47static const char *mpls_labelname[] = {
48/*0*/	"IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
49	"implicit NULL", "rsvd",
50/*5*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
51/*10*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
52/*15*/	"rsvd",
53};
54
55enum mpls_packet_type {
56	PT_UNKNOWN,
57	PT_IPV4,
58	PT_IPV6,
59	PT_OSI
60};
61
62/*
63 * RFC3032: MPLS label stack encoding
64 */
65void
66mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
67{
68	const u_char *p;
69	uint32_t label_entry;
70	uint16_t label_stack_depth = 0;
71	uint8_t first;
72	enum mpls_packet_type pt = PT_UNKNOWN;
73
74	ndo->ndo_protocol = "mpls";
75	p = bp;
76	nd_print_protocol_caps(ndo);
77	do {
78		if (length < sizeof(label_entry))
79			goto invalid;
80		label_entry = GET_BE_U_4(p);
81		ND_PRINT("%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(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
88		ND_PRINT(", tc %u", MPLS_TC(label_entry));
89		if (MPLS_STACK(label_entry))
90			ND_PRINT(", [S]");
91		ND_PRINT(", 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		if (length < 1) {
138			/* nothing to print */
139			return;
140		}
141		first = GET_U_1(p);
142		pt =
143			(first >= 0x45 && first <= 0x4f) ? PT_IPV4 :
144			(first >= 0x60 && first <= 0x6f) ? PT_IPV6 :
145			(first >= 0x81 && first <= 0x83) ? PT_OSI :
146			/* ok bail out - we did not figure out what it is*/
147			PT_UNKNOWN;
148	}
149
150	/*
151	 * Print the payload.
152	 */
153	switch (pt) {
154	case PT_UNKNOWN:
155		if (!ndo->ndo_suppress_default_print)
156			ND_DEFAULTPRINT(p, length);
157		break;
158
159	case PT_IPV4:
160		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
161		ip_print(ndo, p, length);
162		break;
163
164	case PT_IPV6:
165		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
166		ip6_print(ndo, p, length);
167		break;
168
169	case PT_OSI:
170		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
171		isoclns_print(ndo, p, length);
172		break;
173	}
174	return;
175
176invalid:
177	nd_print_invalid(ndo);
178	ND_TCHECK_LEN(p, length);
179}
180