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 /* \summary: Multi-Protocol Label Switching (MPLS) printer */
  30
  31 #ifdef HAVE_CONFIG_H
  32 #include <config.h>
  33 #endif
  34
  35 #include "netdissect-stdinc.h"
  36
  37 #include "netdissect.h"
  38 #include "extract.h"
  39 #include "mpls.h"
  40
  41 static const char *mpls_labelname[] = {
  42 /*0*/   "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
  43         "implicit NULL", "rsvd",
  44 /*5*/   "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  45 /*10*/  "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  46 /*15*/  "rsvd",
  47 };
  48
  49 enum mpls_packet_type {
  50         PT_UNKNOWN,
  51         PT_IPV4,
  52         PT_IPV6,
  53         PT_OSI
  54 };
  55
  56 /*
  57  * RFC3032: MPLS label stack encoding
  58  */
  59 void
  60 mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
  61 {
  62         const u_char *p;
  63         uint32_t label_entry;
  64         uint16_t label_stack_depth = 0;
  65         enum mpls_packet_type pt = PT_UNKNOWN;
  66
  67         ndo->ndo_protocol = "mpls";
  68         p = bp;
  69         ND_PRINT("MPLS");
  70         do {
  71                 ND_TCHECK_LEN(p, sizeof(label_entry));
  72                 if (length < sizeof(label_entry)) {
  73                         ND_PRINT("[|MPLS], length %u", length);
  74                         return;
  75                 }
  76                 label_entry = EXTRACT_BE_U_4(p);
  77                 ND_PRINT("%s(label %u",
  78                        (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
  79                        MPLS_LABEL(label_entry));
  80                 label_stack_depth++;
  81                 if (ndo->ndo_vflag &&
  82                     MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
  83                         ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
  84                 ND_PRINT(", exp %u", MPLS_EXP(label_entry));
  85                 if (MPLS_STACK(label_entry))
  86                         ND_PRINT(", [S]");
  87                 ND_PRINT(", ttl %u)", MPLS_TTL(label_entry));
  88
  89                 p += sizeof(label_entry);
  90                 length -= sizeof(label_entry);
  91         } while (!MPLS_STACK(label_entry));
  92
  93         /*
  94          * Try to figure out the packet type.
  95          */
  96         switch (MPLS_LABEL(label_entry)) {
  97
  98         case 0: /* IPv4 explicit NULL label */
  99         case 3: /* IPv4 implicit NULL label */
 100                 pt = PT_IPV4;
 101                 break;
 102
 103         case 2: /* IPv6 explicit NULL label */
 104                 pt = PT_IPV6;
 105                 break;
 106
 107         default:
 108                 /*
 109                  * Generally there's no indication of protocol in MPLS label
 110                  * encoding.
 111                  *
 112                  * However, draft-hsmit-isis-aal5mux-00.txt describes a
 113                  * technique for encapsulating IS-IS and IP traffic on the
 114                  * same ATM virtual circuit; you look at the first payload
 115                  * byte to determine the network layer protocol, based on
 116                  * the fact that
 117                  *
 118                  *      1) the first byte of an IP header is 0x45-0x4f
 119                  *         for IPv4 and 0x60-0x6f for IPv6;
 120                  *
 121                  *      2) the first byte of an OSI CLNP packet is 0x81,
 122                  *         the first byte of an OSI ES-IS packet is 0x82,
 123                  *         and the first byte of an OSI IS-IS packet is
 124                  *         0x83;
 125                  *
 126                  * so the network layer protocol can be inferred from the
 127                  * first byte of the packet, if the protocol is one of the
 128                  * ones listed above.
 129                  *
 130                  * Cisco sends control-plane traffic MPLS-encapsulated in
 131                  * this fashion.
 132                  */
 133                 ND_TCHECK_1(p);
 134                 if (length < 1) {
 135                         /* nothing to print */
 136                         return;
 137                 }
 138                 switch(EXTRACT_U_1(p)) {
 139
 140                 case 0x45:
 141                 case 0x46:
 142                 case 0x47:
 143                 case 0x48:
 144                 case 0x49:
 145                 case 0x4a:
 146                 case 0x4b:
 147                 case 0x4c:
 148                 case 0x4d:
 149                 case 0x4e:
 150                 case 0x4f:
 151                         pt = PT_IPV4;
 152                         break;
 153
 154                 case 0x60:
 155                 case 0x61:
 156                 case 0x62:
 157                 case 0x63:
 158                 case 0x64:
 159                 case 0x65:
 160                 case 0x66:
 161                 case 0x67:
 162                 case 0x68:
 163                 case 0x69:
 164                 case 0x6a:
 165                 case 0x6b:
 166                 case 0x6c:
 167                 case 0x6d:
 168                 case 0x6e:
 169                 case 0x6f:
 170                         pt = PT_IPV6;
 171                         break;
 172
 173                 case 0x81:
 174                 case 0x82:
 175                 case 0x83:
 176                         pt = PT_OSI;
 177                         break;
 178
 179                 default:
 180                         /* ok bail out - we did not figure out what it is*/
 181                         break;
 182                 }
 183         }
 184
 185         /*
 186          * Print the payload.
 187          */
 188         if (pt == PT_UNKNOWN) {
 189                 if (!ndo->ndo_suppress_default_print)
 190                         ND_DEFAULTPRINT(p, length);
 191                 return;
 192         }
 193         ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
 194         switch (pt) {
 195
 196         case PT_IPV4:
 197                 ip_print(ndo, p, length);
 198                 break;
 199
 200         case PT_IPV6:
 201                 ip6_print(ndo, p, length);
 202                 break;
 203
 204         case PT_OSI:
 205                 isoclns_print(ndo, p, length);
 206                 break;
 207
 208         default:
 209                 break;
 210         }
 211         return;
 212
 213 trunc:
 214         nd_print_trunc(ndo);
 215 }