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 #define NETDISSECT_REWORKED
  30 #ifdef HAVE_CONFIG_H
  31 #include "config.h"
  32 #endif
  33
  34 #include <tcpdump-stdinc.h>
  35
  36 #include "interface.h"
  37 #include "extract.h"                    /* must come after interface.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
  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         enum mpls_packet_type pt = PT_UNKNOWN;
  65
  66         p = bp;
  67         ND_PRINT((ndo, "MPLS"));
  68         do {
  69                 ND_TCHECK2(*p, sizeof(label_entry));
  70                 label_entry = EXTRACT_32BITS(p);
  71                 ND_PRINT((ndo, "%s(label %u",
  72                        (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
  73                        MPLS_LABEL(label_entry)));
  74                 label_stack_depth++;
  75                 if (ndo->ndo_vflag &&
  76                     MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
  77                         ND_PRINT((ndo, " (%s)", mpls_labelname[MPLS_LABEL(label_entry)]));
  78                 ND_PRINT((ndo, ", exp %u", MPLS_EXP(label_entry)));
  79                 if (MPLS_STACK(label_entry))
  80                         ND_PRINT((ndo, ", [S]"));
  81                 ND_PRINT((ndo, ", ttl %u)", MPLS_TTL(label_entry)));
  82
  83                 p += sizeof(label_entry);
  84         } while (!MPLS_STACK(label_entry));
  85
  86         /*
  87          * Try to figure out the packet type.
  88          */
  89         switch (MPLS_LABEL(label_entry)) {
  90
  91         case 0: /* IPv4 explicit NULL label */
  92         case 3: /* IPv4 implicit NULL label */
  93                 pt = PT_IPV4;
  94                 break;
  95
  96         case 2: /* IPv6 explicit NULL label */
  97                 pt = PT_IPV6;
  98                 break;
  99
 100         default:
 101                 /*
 102                  * Generally there's no indication of protocol in MPLS label
 103                  * encoding.
 104                  *
 105                  * However, draft-hsmit-isis-aal5mux-00.txt describes a
 106                  * technique for encapsulating IS-IS and IP traffic on the
 107                  * same ATM virtual circuit; you look at the first payload
 108                  * byte to determine the network layer protocol, based on
 109                  * the fact that
 110                  *
 111                  *      1) the first byte of an IP header is 0x45-0x4f
 112                  *         for IPv4 and 0x60-0x6f for IPv6;
 113                  *
 114                  *      2) the first byte of an OSI CLNP packet is 0x81,
 115                  *         the first byte of an OSI ES-IS packet is 0x82,
 116                  *         and the first byte of an OSI IS-IS packet is
 117                  *         0x83;
 118                  *
 119                  * so the network layer protocol can be inferred from the
 120                  * first byte of the packet, if the protocol is one of the
 121                  * ones listed above.
 122                  *
 123                  * Cisco sends control-plane traffic MPLS-encapsulated in
 124                  * this fashion.
 125                  */
 126                 switch(*p) {
 127
 128                 case 0x45:
 129                 case 0x46:
 130                 case 0x47:
 131                 case 0x48:
 132                 case 0x49:
 133                 case 0x4a:
 134                 case 0x4b:
 135                 case 0x4c:
 136                 case 0x4d:
 137                 case 0x4e:
 138                 case 0x4f:
 139                         pt = PT_IPV4;
 140                         break;
 141
 142                 case 0x60:
 143                 case 0x61:
 144                 case 0x62:
 145                 case 0x63:
 146                 case 0x64:
 147                 case 0x65:
 148                 case 0x66:
 149                 case 0x67:
 150                 case 0x68:
 151                 case 0x69:
 152                 case 0x6a:
 153                 case 0x6b:
 154                 case 0x6c:
 155                 case 0x6d:
 156                 case 0x6e:
 157                 case 0x6f:
 158                         pt = PT_IPV6;
 159                         break;
 160
 161                 case 0x81:
 162                 case 0x82:
 163                 case 0x83:
 164                         pt = PT_OSI;
 165                         break;
 166
 167                 default:
 168                         /* ok bail out - we did not figure out what it is*/
 169                         break;
 170                 }
 171         }
 172
 173         /*
 174          * Print the payload.
 175          */
 176         if (pt == PT_UNKNOWN) {
 177                 if (!ndo->ndo_suppress_default_print)
 178                         ND_DEFAULTPRINT(p, length - (p - bp));
 179                 return;
 180         }
 181         ND_PRINT((ndo, ndo->ndo_vflag ? "\n\t" : " "));
 182         switch (pt) {
 183
 184         case PT_IPV4:
 185                 ip_print(ndo, p, length - (p - bp));
 186                 break;
 187
 188         case PT_IPV6:
 189                 ip6_print(ndo, p, length - (p - bp));
 190                 break;
 191
 192         case PT_OSI:
 193                 isoclns_print(ndo, p, length - (p - bp), length - (p - bp));
 194                 break;
 195
 196         default:
 197                 break;
 198         }
 199         return;
 200
 201 trunc:
 202         ND_PRINT((ndo, "[|MPLS]"));
 203 }
 204
 205
 206 /*
 207  * Local Variables:
 208  * c-style: whitesmith
 209  * c-basic-offset: 8
 210  * End:
 211  */