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