The Tcpdump Group git mirrors - tcpdump/blob - print-mpls.c

   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 #ifdef HAVE_CONFIG_H
  30 #include "config.h"
  31 #endif
  32
  33 #include <netdissect-stdinc.h>
  34
  35 #include "netdissect.h"
  36 #include "extract.h"
  37 #include "mpls.h"
  38
  39 static const char *mpls_labelname[] = {
  40 /*0*/   "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
  41         "implicit NULL", "rsvd",
  42 /*5*/   "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  43 /*10*/  "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  44 /*15*/  "rsvd",
  45 };
  46
  47 enum mpls_packet_type {
  48         PT_UNKNOWN,
  49         PT_IPV4,
  50         PT_IPV6,
  51         PT_OSI
  52 };
  53
  54 /*
  55  * RFC3032: MPLS label stack encoding
  56  */
  57 void
  58 mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
  59 {
  60         const u_char *p;
  61         uint32_t label_entry;
  62         uint16_t label_stack_depth = 0;
  63         enum mpls_packet_type pt = PT_UNKNOWN;
  64
  65         p = bp;
  66         ND_PRINT((ndo, "MPLS"));
  67         do {
  68                 ND_TCHECK2(*p, sizeof(label_entry));
  69                 label_entry = EXTRACT_32BITS(p);
  70                 ND_PRINT((ndo, "%s(label %u",
  71                        (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
  72                        MPLS_LABEL(label_entry)));
  73                 label_stack_depth++;
  74                 if (ndo->ndo_vflag &&
  75                     MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
  76                         ND_PRINT((ndo, " (%s)", mpls_labelname[MPLS_LABEL(label_entry)]));
  77                 ND_PRINT((ndo, ", exp %u", MPLS_EXP(label_entry)));
  78                 if (MPLS_STACK(label_entry))
  79                         ND_PRINT((ndo, ", [S]"));
  80                 ND_PRINT((ndo, ", ttl %u)", MPLS_TTL(label_entry)));
  81
  82                 p += sizeof(label_entry);
  83         } while (!MPLS_STACK(label_entry));
  84
  85         /*
  86          * Try to figure out the packet type.
  87          */
  88         switch (MPLS_LABEL(label_entry)) {
  89
  90         case 0: /* IPv4 explicit NULL label */
  91         case 3: /* IPv4 implicit NULL label */
  92                 pt = PT_IPV4;
  93                 break;
  94
  95         case 2: /* IPv6 explicit NULL label */
  96                 pt = PT_IPV6;
  97                 break;
  98
  99         default:
 100                 /*
 101                  * Generally there's no indication of protocol in MPLS label
 102                  * encoding.
 103                  *
 104                  * However, draft-hsmit-isis-aal5mux-00.txt describes a
 105                  * technique for encapsulating IS-IS and IP traffic on the
 106                  * same ATM virtual circuit; you look at the first payload
 107                  * byte to determine the network layer protocol, based on
 108                  * the fact that
 109                  *
 110                  *      1) the first byte of an IP header is 0x45-0x4f
 111                  *         for IPv4 and 0x60-0x6f for IPv6;
 112                  *
 113                  *      2) the first byte of an OSI CLNP packet is 0x81,
 114                  *         the first byte of an OSI ES-IS packet is 0x82,
 115                  *         and the first byte of an OSI IS-IS packet is
 116                  *         0x83;
 117                  *
 118                  * so the network layer protocol can be inferred from the
 119                  * first byte of the packet, if the protocol is one of the
 120                  * ones listed above.
 121                  *
 122                  * Cisco sends control-plane traffic MPLS-encapsulated in
 123                  * this fashion.
 124                  */
 125                 switch(*p) {
 126
 127                 case 0x45:
 128                 case 0x46:
 129                 case 0x47:
 130                 case 0x48:
 131                 case 0x49:
 132                 case 0x4a:
 133                 case 0x4b:
 134                 case 0x4c:
 135                 case 0x4d:
 136                 case 0x4e:
 137                 case 0x4f:
 138                         pt = PT_IPV4;
 139                         break;
 140
 141                 case 0x60:
 142                 case 0x61:
 143                 case 0x62:
 144                 case 0x63:
 145                 case 0x64:
 146                 case 0x65:
 147                 case 0x66:
 148                 case 0x67:
 149                 case 0x68:
 150                 case 0x69:
 151                 case 0x6a:
 152                 case 0x6b:
 153                 case 0x6c:
 154                 case 0x6d:
 155                 case 0x6e:
 156                 case 0x6f:
 157                         pt = PT_IPV6;
 158                         break;
 159
 160                 case 0x81:
 161                 case 0x82:
 162                 case 0x83:
 163                         pt = PT_OSI;
 164                         break;
 165
 166                 default:
 167                         /* ok bail out - we did not figure out what it is*/
 168                         break;
 169                 }
 170         }
 171
 172         /*
 173          * Print the payload.
 174          */
 175         if (pt == PT_UNKNOWN) {
 176                 if (!ndo->ndo_suppress_default_print)
 177                         ND_DEFAULTPRINT(p, length - (p - bp));
 178                 return;
 179         }
 180         ND_PRINT((ndo, ndo->ndo_vflag ? "\n\t" : " "));
 181         switch (pt) {
 182
 183         case PT_IPV4:
 184                 ip_print(ndo, p, length - (p - bp));
 185                 break;
 186
 187         case PT_IPV6:
 188                 ip6_print(ndo, p, length - (p - bp));
 189                 break;
 190
 191         case PT_OSI:
 192                 isoclns_print(ndo, p, length - (p - bp), length - (p - bp));
 193                 break;
 194
 195         default:
 196                 break;
 197         }
 198         return;
 199
 200 trunc:
 201         ND_PRINT((ndo, "[|MPLS]"));
 202 }
 203
 204
 205 /*
 206  * Local Variables:
 207  * c-style: whitesmith
 208  * c-basic-offset: 8
 209  * End:
 210  */