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 #ifndef lint
  30 static const char rcsid[] _U_ =
  31     "@(#) $Header: /tcpdump/master/tcpdump/print-mpls.c,v 1.14 2005-07-05 09:38:19 hannes Exp $ (LBL)";
  32 #endif
  33
  34 #ifdef HAVE_CONFIG_H
  35 #include "config.h"
  36 #endif
  37
  38 #include <tcpdump-stdinc.h>
  39
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43
  44 #include "addrtoname.h"
  45 #include "interface.h"
  46 #include "extract.h"                    /* must come after interface.h */
  47 #include "mpls.h"
  48
  49 static const char *mpls_labelname[] = {
  50 /*0*/   "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
  51         "implicit NULL", "rsvd",
  52 /*5*/   "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  53 /*10*/  "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  54 /*15*/  "rsvd",
  55 };
  56
  57 enum mpls_packet_type {
  58         PT_UNKNOWN,
  59         PT_IPV4,
  60         PT_IPV6,
  61         PT_OSI
  62 };
  63
  64 /*
  65  * RFC3032: MPLS label stack encoding
  66  */
  67 void
  68 mpls_print(const u_char *bp, u_int length)
  69 {
  70         const u_char *p;
  71         u_int32_t label_entry;
  72         u_int16_t label_stack_depth = 0;
  73         enum mpls_packet_type pt = PT_UNKNOWN;
  74
  75         p = bp;
  76         printf("MPLS");
  77         do {
  78                 TCHECK2(*p, sizeof(label_entry));
  79                 label_entry = EXTRACT_32BITS(p);
  80                 printf("%s(label %u",
  81                        (label_stack_depth && vflag) ? "\n\t" : " ",
  82                        MPLS_LABEL(label_entry));
  83                 label_stack_depth++;
  84                 if (vflag &&
  85                     MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
  86                         printf(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
  87                 printf(", exp %u", MPLS_EXP(label_entry));
  88                 if (MPLS_STACK(label_entry))
  89                         printf(", [S]");
  90                 printf(", ttl %u)", MPLS_TTL(label_entry));
  91
  92                 p += 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, however draft-hsmit-isis-aal5mux-00.txt describes
 113                  * a technique that looks at the first payload byte if the BOS (bottom of stack)
 114                  * bit is set and tries to determine the network layer protocol
 115                  * 0x45-0x4f is IPv4
 116                  * 0x60-0x6f is IPv6
 117                  * 0x81-0x83 is OSI (CLNP,ES-IS,IS-IS)
 118                  * this technique is sometimes known as NULL encapsulation
 119                  * and decoding is particularly useful for control-plane traffic [BGP]
 120                  * which cisco by default sends MPLS encapsulated
 121                  */
 122                 if (MPLS_STACK(label_entry)) { /* only do this if the stack bit is set */
 123                         switch(*p) {
 124
 125                         case 0x45:
 126                         case 0x46:
 127                         case 0x47:
 128                         case 0x48:
 129                         case 0x49:
 130                         case 0x4a:
 131                         case 0x4b:
 132                         case 0x4c:
 133                         case 0x4d:
 134                         case 0x4e:
 135                         case 0x4f:
 136                                 pt = PT_IPV4;
 137                                 break;
 138
 139                         case 0x60:
 140                         case 0x61:
 141                         case 0x62:
 142                         case 0x63:
 143                         case 0x64:
 144                         case 0x65:
 145                         case 0x66:
 146                         case 0x67:
 147                         case 0x68:
 148                         case 0x69:
 149                         case 0x6a:
 150                         case 0x6b:
 151                         case 0x6c:
 152                         case 0x6d:
 153                         case 0x6e:
 154                         case 0x6f:
 155                                 pt = PT_IPV6;
 156                                 break;
 157
 158                         case 0x81:
 159                         case 0x82:
 160                         case 0x83:
 161                                 pt = PT_OSI;
 162                                 break;
 163
 164                         default:
 165                                 /* ok bail out - we did not figure out what it is*/
 166                                 break;
 167                         }
 168                 }
 169         }
 170
 171         /*
 172          * Print the payload.
 173          */
 174         if (pt == PT_UNKNOWN) {
 175                 if (!suppress_default_print)
 176                         default_print(p, length - (p - bp));
 177                 return;
 178         }
 179         if (vflag)
 180                 printf("\n\t");
 181         else
 182                 printf(" ");
 183         switch (pt) {
 184
 185         case PT_IPV4:
 186                 ip_print(gndo, p, length - (p - bp));
 187                 break;
 188
 189         case PT_IPV6:
 190 #ifdef INET6
 191                 ip6_print(p, length - (p - bp));
 192 #else
 193                 printf("IPv6, length: %u", length);
 194 #endif
 195                 break;
 196
 197         case PT_OSI:
 198                 isoclns_print(p, length - (p - bp), length - (p - bp));
 199                 break;
 200
 201         default:
 202                 break;
 203         }
 204         return;
 205
 206 trunc:
 207         printf("[|MPLS]");
 208 }
 209
 210
 211 /*
 212  * Local Variables:
 213  * c-style: whitesmith
 214  * c-basic-offset: 8
 215  * End:
 216  */