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[] =
  31     "@(#) $Header: /tcpdump/master/tcpdump/print-mpls.c,v 1.5 2002-08-08 19:52:48 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
  48 #define LABEL_MASK      0xfffff000
  49 #define LABEL_SHIFT     12
  50 #define EXP_MASK        0x00000e00
  51 #define EXP_SHIFT       9
  52 #define STACK_MASK      0x00000100
  53 #define STACK_SHIFT     8
  54 #define TTL_MASK        0x000000ff
  55 #define TTL_SHIFT       0
  56
  57 #define MPLS_LABEL(x)   (((x) & LABEL_MASK) >> LABEL_SHIFT)
  58 #define MPLS_EXP(x)     (((x) & EXP_MASK) >> EXP_SHIFT)
  59 #define MPLS_STACK(x)   (((x) & STACK_MASK) >> STACK_SHIFT)
  60 #define MPLS_TTL(x)     (((x) & TTL_MASK) >> TTL_SHIFT)
  61
  62 static const char *mpls_labelname[] = {
  63 /*0*/   "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
  64         "implicit NULL", "rsvd",
  65 /*5*/   "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  66 /*10*/  "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
  67 /*15*/  "rsvd",
  68 };
  69
  70 /*
  71  * RFC3032: MPLS label stack encoding
  72  */
  73 void
  74 mpls_print(const u_char *bp, u_int length)
  75 {
  76         const u_char *p;
  77         u_int32_t v;
  78
  79         p = bp;
  80         printf("MPLS");
  81         do {
  82                 TCHECK2(*p, sizeof(v));
  83                 v = EXTRACT_32BITS(p);
  84                 printf(" (");   /*)*/
  85                 printf("label %u", MPLS_LABEL(v));
  86                 if (vflag &&
  87                     MPLS_LABEL(v) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
  88                         printf(" (%s)", mpls_labelname[MPLS_LABEL(v)]);
  89                 if (MPLS_EXP(v))
  90                         printf(", exp %u", MPLS_EXP(v));
  91                 if (MPLS_STACK(v))
  92                         printf(", [S]");
  93                 printf(", ttl %u", MPLS_TTL(v));
  94                 /*(*/
  95                 printf(")");
  96
  97                 p += sizeof(v);
  98         } while (!MPLS_STACK(v));
  99
 100         switch (MPLS_LABEL(v)) {
 101         case 0: /* IPv4 explicit NULL label */
 102         case 3: /* IPv4 implicit NULL label */
 103                 ip_print(p, length - (p - bp));
 104                 break;
 105 #ifdef INET6
 106         case 2: /* IPv6 explicit NULL label */
 107                 ip6_print(p, length - (p - bp));
 108                 break;
 109 #endif
 110         default:
 111                 /*
 112                  * Generally there's no indication of protocol in MPLS label
 113                  * encoding, however draft-hsmit-isis-aal5mux-00.txt describes
 114                  * a technique that looks at the first payload byte if the BOS (bottom of stack)
 115                  * bit is set and tries to determine the network layer protocol
 116                  * 0x45-0x4f is IPv4
 117                  * 0x60-0x6f is IPv6
 118                  * 0x83      is IS-IS
 119                  * this technique is sometimes known as NULL encapsulation
 120                  * and decoding is particularly useful for control-plane traffic [BGP]
 121                  * which cisco by default sends MPLS encapsulated
 122                  */
 123
 124                 if (MPLS_STACK(v)) { /* only do this if the stack bit is set */
 125                     switch(*p) {
 126                     case 0x45:
 127                     case 0x46:
 128                     case 0x47:
 129                     case 0x48:
 130                     case 0x49:
 131                     case 0x4a:
 132                     case 0x4b:
 133                     case 0x4c:
 134                     case 0x4d:
 135                     case 0x4e:
 136                     case 0x4f:
 137                         printf("\n\t");
 138                         ip_print(p, length - (p - bp));
 139                         break;
 140 #ifdef INET6
 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                         printf("\n\t");
 158                         ip6_print(p, length - (p - bp));
 159                         break;
 160 #endif
 161                     case 0x83:
 162                         printf("\n\t");
 163                         isoclns_print(p, length - (p - bp), length - (p - bp), NULL, NULL);
 164                         break;
 165                     default:
 166                         /* ok bail out - we did not figure out what it is*/
 167                         break;
 168                     }
 169                 }
 170                 return;
 171         }
 172
 173 trunc:
 174         printf("[|MPLS]");
 175 }
 176