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 1.10 2024/09/02 16:15:32 christos Exp $");
32 #endif
33
34 /* \summary: Multi-Protocol Label Switching (MPLS) printer */
35
36 #include <config.h>
37
38 #include "netdissect-stdinc.h"
39
40 #define ND_LONGJMP_FROM_TCHECK
41 #include "netdissect.h"
42 #include "extract.h"
43 #include "mpls.h"
44
45 static const char *mpls_labelname[] = {
46 /*0*/ "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
47 "implicit NULL", "rsvd",
48 /*5*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
49 /*10*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
50 /*15*/ "rsvd",
51 };
52
53 enum mpls_packet_type {
54 PT_UNKNOWN,
55 PT_IPV4,
56 PT_IPV6,
57 PT_OSI
58 };
59
60 /*
61 * RFC3032: MPLS label stack encoding
62 */
63 void
mpls_print(netdissect_options * ndo,const u_char * bp,u_int length)64 mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
65 {
66 const u_char *p;
67 uint32_t label_entry;
68 uint16_t label_stack_depth = 0;
69 uint8_t first;
70 enum mpls_packet_type pt = PT_UNKNOWN;
71
72 ndo->ndo_protocol = "mpls";
73 p = bp;
74 nd_print_protocol_caps(ndo);
75 do {
76 if (length < sizeof(label_entry))
77 goto invalid;
78 label_entry = GET_BE_U_4(p);
79 ND_PRINT("%s(label %u",
80 (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
81 MPLS_LABEL(label_entry));
82 label_stack_depth++;
83 if (ndo->ndo_vflag &&
84 MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
85 ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
86 ND_PRINT(", tc %u", MPLS_TC(label_entry));
87 if (MPLS_STACK(label_entry))
88 ND_PRINT(", [S]");
89 ND_PRINT(", ttl %u)", MPLS_TTL(label_entry));
90
91 p += sizeof(label_entry);
92 length -= sizeof(label_entry);
93 } while (!MPLS_STACK(label_entry));
94
95 /*
96 * Try to figure out the packet type.
97 */
98 switch (MPLS_LABEL(label_entry)) {
99
100 case 0: /* IPv4 explicit NULL label */
101 case 3: /* IPv4 implicit NULL label */
102 pt = PT_IPV4;
103 break;
104
105 case 2: /* IPv6 explicit NULL label */
106 pt = PT_IPV6;
107 break;
108
109 default:
110 /*
111 * Generally there's no indication of protocol in MPLS label
112 * encoding.
113 *
114 * However, draft-hsmit-isis-aal5mux-00.txt describes a
115 * technique for encapsulating IS-IS and IP traffic on the
116 * same ATM virtual circuit; you look at the first payload
117 * byte to determine the network layer protocol, based on
118 * the fact that
119 *
120 * 1) the first byte of an IP header is 0x45-0x4f
121 * for IPv4 and 0x60-0x6f for IPv6;
122 *
123 * 2) the first byte of an OSI CLNP packet is 0x81,
124 * the first byte of an OSI ES-IS packet is 0x82,
125 * and the first byte of an OSI IS-IS packet is
126 * 0x83;
127 *
128 * so the network layer protocol can be inferred from the
129 * first byte of the packet, if the protocol is one of the
130 * ones listed above.
131 *
132 * Cisco sends control-plane traffic MPLS-encapsulated in
133 * this fashion.
134 */
135 if (length < 1) {
136 /* nothing to print */
137 return;
138 }
139 first = GET_U_1(p);
140 pt =
141 (first >= 0x45 && first <= 0x4f) ? PT_IPV4 :
142 (first >= 0x60 && first <= 0x6f) ? PT_IPV6 :
143 (first >= 0x81 && first <= 0x83) ? PT_OSI :
144 /* ok bail out - we did not figure out what it is*/
145 PT_UNKNOWN;
146 }
147
148 /*
149 * Print the payload.
150 */
151 switch (pt) {
152 case PT_UNKNOWN:
153 if (!ndo->ndo_suppress_default_print)
154 ND_DEFAULTPRINT(p, length);
155 break;
156
157 case PT_IPV4:
158 ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
159 ip_print(ndo, p, length);
160 break;
161
162 case PT_IPV6:
163 ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
164 ip6_print(ndo, p, length);
165 break;
166
167 case PT_OSI:
168 ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
169 isoclns_print(ndo, p, length);
170 break;
171 }
172 return;
173
174 invalid:
175 nd_print_invalid(ndo);
176 ND_TCHECK_LEN(p, length);
177 }
178