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print-mpls.c

/*
 * Copyright (C) 2001 WIDE Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/print-mpls.c,v 1.8.2.2 2003/11/16 08:51:34 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "addrtoname.h"
#include "interface.h"
#include "extract.h"                /* must come after interface.h */

#define LABEL_MASK      0xfffff000
#define LABEL_SHIFT     12
#define     EXP_MASK    0x00000e00
#define EXP_SHIFT 9
#define     STACK_MASK  0x00000100
#define STACK_SHIFT     8
#define TTL_MASK  0x000000ff
#define TTL_SHIFT 0

#define MPLS_LABEL(x)   (((x) & LABEL_MASK) >> LABEL_SHIFT)
#define MPLS_EXP(x)     (((x) & EXP_MASK) >> EXP_SHIFT)
#define MPLS_STACK(x)   (((x) & STACK_MASK) >> STACK_SHIFT)
#define MPLS_TTL(x)     (((x) & TTL_MASK) >> TTL_SHIFT)

static const char *mpls_labelname[] = {
/*0*/ "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
      "implicit NULL", "rsvd",
/*5*/ "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
/*10*/      "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
/*15*/      "rsvd",
};

/*
 * RFC3032: MPLS label stack encoding
 */
void
mpls_print(const u_char *bp, u_int length)
{
      const u_char *p;
      u_int32_t v;

      p = bp;
      printf("MPLS");
      do {
            TCHECK2(*p, sizeof(v));
            v = EXTRACT_32BITS(p);
            printf(" (");     /*)*/
            printf("label %u", MPLS_LABEL(v));
            if (vflag &&
                MPLS_LABEL(v) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
                  printf(" (%s)", mpls_labelname[MPLS_LABEL(v)]);
            printf(", exp %u", MPLS_EXP(v));
            if (MPLS_STACK(v))
                  printf(", [S]");
            printf(", ttl %u", MPLS_TTL(v));
            /*(*/
            printf(")");

            p += sizeof(v);
      } while (!MPLS_STACK(v));

      switch (MPLS_LABEL(v)) {
      case 0:     /* IPv4 explicit NULL label */
        case 3:   /* IPv4 implicit NULL label */
            ip_print(p, length - (p - bp));
            break;
#ifdef INET6
      case 2:     /* IPv6 explicit NULL label */
            ip6_print(p, length - (p - bp));
            break;
#endif
      default:
            /*
             * Generally there's no indication of protocol in MPLS label
             * encoding, however draft-hsmit-isis-aal5mux-00.txt describes
                 * a technique that looks at the first payload byte if the BOS (bottom of stack)
                 * bit is set and tries to determine the network layer protocol
                 * 0x45-0x4f is IPv4
                 * 0x60-0x6f is IPv6
                 * 0x81-0x83 is OSI (CLNP,ES-IS,IS-IS)
                 * this technique is sometimes known as NULL encapsulation
                 * and decoding is particularly useful for control-plane traffic [BGP]
                 * which cisco by default sends MPLS encapsulated
             */

                if (MPLS_STACK(v)) { /* only do this if the stack bit is set */
                    switch(*p) {
                    case 0x45:
                    case 0x46:
                    case 0x47:
                    case 0x48:
                    case 0x49:
                    case 0x4a:
                    case 0x4b:
                    case 0x4c:
                    case 0x4d:
                    case 0x4e:
                    case 0x4f:
                    if (vflag>0) {
                            printf("\n\t");
                            ip_print(p, length - (p - bp));
                      }
                        else printf(", IP, length: %u",length);
                        break;
#ifdef INET6
                    case 0x60:
                    case 0x61:
                    case 0x62:
                    case 0x63:
                    case 0x64:
                    case 0x65:
                    case 0x66:
                    case 0x67:
                    case 0x68:
                    case 0x69:
                    case 0x6a:
                    case 0x6b:
                    case 0x6c:
                    case 0x6d:
                    case 0x6e:
                    case 0x6f:
                    if (vflag>0) {
                            printf("\n\t");
                            ip6_print(p, length - (p - bp));
                            }
                  else printf(", IPv6, length: %u",length);
                        break;
#endif
                    case 0x81:
                    case 0x82:
                    case 0x83:
                    if (vflag>0) {
                            printf("\n\t");
                            isoclns_print(p, length - (p - bp), length - (p - bp));
                      }
                  else printf(", OSI, length: %u",length);
                        break;
                    default:
                        /* ok bail out - we did not figure out what it is*/
                        break;
                    }
                }
                return;
      }

trunc:
      printf("[|MPLS]");
}

/*
 * draft-ietf-mpls-lsp-ping-02.txt
 */
void
mpls_lsp_ping_print(const u_char *pptr, u_int length)
{
    printf("UDP, LSP-PING, length: %u", length);
    if (vflag >1)
      print_unknown_data(pptr,"\n\t  ", length);
}

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