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 #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
  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 }