Logo Search packages:      
Sourcecode: tcpdump version File versions

print-gre.c

/*    $OpenBSD: print-gre.c,v 1.6 2002/10/30 03:04:04 fgsch Exp $ */

/*
 * Copyright (c) 2002 Jason L. Wright (jason@thought.net)
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by Jason L. Wright
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/*
 * tcpdump filter for GRE - Generic Routing Encapsulation
 * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/print-gre.c,v 1.22.2.2 2003/11/16 08:51:24 guy Exp $ (LBL)";
#endif

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

#include <tcpdump-stdinc.h>

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

#include "interface.h"
#include "addrtoname.h"
#include "extract.h"

#include "ip.h"

#define     GRE_CP            0x8000            /* checksum present */
#define     GRE_RP            0x4000            /* routing present */
#define     GRE_KP            0x2000            /* key present */
#define     GRE_SP            0x1000            /* sequence# present */
#define     GRE_sP            0x0800            /* source routing */
#define     GRE_RECRS   0x0700            /* recursion count */
#define     GRE_AP            0x0080            /* acknowledgment# present */
#define     GRE_VERS    0x0007            /* protocol version */

#define     GREPROTO_IP 0x0800            /* IP */
#define     GREPROTO_PPP      0x880b            /* PPTP */
#define     GREPROTO_ISO      0x00fe            /* OSI */

/* source route entry types */
#define     GRESRE_IP   0x0800            /* IP */
#define     GRESRE_ASN  0xfffe            /* ASN */

void gre_print_0(const u_char *, u_int);
void gre_print_1(const u_char *, u_int);
void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);

void
gre_print(const u_char *bp, u_int length)
{
      u_int len = length, vers;

      if (len < 2) {
            printf("[|gre]");
            return;
      }
      vers = EXTRACT_16BITS(bp) & 7;

      if (vers == 0)
            gre_print_0(bp, len);
      else if (vers == 1)
            gre_print_1(bp, len);
      else
            printf("gre-unknown-version=%u", vers);
      return;

}

void
gre_print_0(const u_char *bp, u_int length)
{
      u_int len = length;
      u_int16_t flags, prot;

      flags = EXTRACT_16BITS(bp);
      if (vflag) {
            printf("[%s%s%s%s%s] ",
                (flags & GRE_CP) ? "C" : "",
                (flags & GRE_RP) ? "R" : "",
                (flags & GRE_KP) ? "K" : "",
                (flags & GRE_SP) ? "S" : "",
                (flags & GRE_sP) ? "s" : "");
      }

      len -= 2;
      bp += 2;

      if (len < 2)
            goto trunc;
      prot = EXTRACT_16BITS(bp);
      len -= 2;
      bp += 2;

      if ((flags & GRE_CP) | (flags & GRE_RP)) {
            if (len < 2)
                  goto trunc;
            if (vflag)
                  printf("sum 0x%x ", EXTRACT_16BITS(bp));
            bp += 2;
            len -= 2;

            if (len < 2)
                  goto trunc;
            printf("off 0x%x ", EXTRACT_16BITS(bp));
            bp += 2;
            len -= 2;
      }

      if (flags & GRE_KP) {
            if (len < 4)
                  goto trunc;
            printf("key=0x%x ", EXTRACT_32BITS(bp));
            bp += 4;
            len -= 4;
      }

      if (flags & GRE_SP) {
            if (len < 4)
                  goto trunc;
            printf("seq %u ", EXTRACT_32BITS(bp));
            bp += 4;
            len -= 4;
      }

      if (flags & GRE_RP) {
            for (;;) {
                  u_int16_t af;
                  u_int8_t sreoff;
                  u_int8_t srelen;

                  if (len < 4)
                        goto trunc;
                  af = EXTRACT_16BITS(bp);
                  sreoff = *(bp + 2);
                  srelen = *(bp + 3);
                  bp += 4;
                  len -= 4;

                  if (af == 0 && srelen == 0)
                        break;

                  gre_sre_print(af, sreoff, srelen, bp, len);

                  if (len < srelen)
                        goto trunc;
                  bp += srelen;
                  len -= srelen;
            }
      }

      switch (prot) {
      case GREPROTO_IP:
            ip_print(bp, len);
            break;
      case GREPROTO_ISO:
            isoclns_print(bp, len, len);
            break;
      default:
            printf("gre-proto-0x%x", prot);
      }
      return;

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

void
gre_print_1(const u_char *bp, u_int length)
{
      u_int len = length;
      u_int16_t flags, prot;

      flags = EXTRACT_16BITS(bp);
      len -= 2;
      bp += 2;

      if (vflag) {
            printf("[%s%s%s%s%s%s] ",
                (flags & GRE_CP) ? "C" : "",
                (flags & GRE_RP) ? "R" : "",
                (flags & GRE_KP) ? "K" : "",
                (flags & GRE_SP) ? "S" : "",
                (flags & GRE_sP) ? "s" : "",
                (flags & GRE_AP) ? "A" : "");
      }

      if (len < 2)
            goto trunc;
      prot = EXTRACT_16BITS(bp);
      len -= 2;
      bp += 2;

      if (flags & GRE_CP) {
            printf("cpset!");
            return;
      }
      if (flags & GRE_RP) {
            printf("rpset!");
            return;
      }
      if ((flags & GRE_KP) == 0) {
            printf("kpunset!");
            return;
      }
      if (flags & GRE_sP) {
            printf("spset!");
            return;
      }

      if (flags & GRE_KP) {
            u_int32_t k;

            if (len < 4)
                  goto trunc;
            k = EXTRACT_32BITS(bp);
            printf("call %d ", k & 0xffff);
            len -= 4;
            bp += 4;
      }

      if (flags & GRE_SP) {
            if (len < 4)
                  goto trunc;
            printf("seq %u ", EXTRACT_32BITS(bp));
            bp += 4;
            len -= 4;
      }

      if (flags & GRE_AP) {
            if (len < 4)
                  goto trunc;
            printf("ack %u ", EXTRACT_32BITS(bp));
            bp += 4;
            len -= 4;
      }

      if ((flags & GRE_SP) == 0) {
            printf("no-payload");
            return;
      }

      switch (prot) {
      case GREPROTO_PPP:
            printf("gre-ppp-payload");
            break;
      default:
            printf("gre-proto-0x%x", prot);
            break;
      }
      return;

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

void
gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
    const u_char *bp, u_int len)
{
      switch (af) {
      case GRESRE_IP:
            printf("(rtaf=ip");
            gre_sre_ip_print(sreoff, srelen, bp, len);
            printf(") ");
            break;
      case GRESRE_ASN:
            printf("(rtaf=asn");
            gre_sre_asn_print(sreoff, srelen, bp, len);
            printf(") ");
            break;
      default:
            printf("(rtaf=0x%x) ", af);
      }
}
void
gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
{
      struct in_addr a;
      const u_char *up = bp;

      if (sreoff & 3) {
            printf(" badoffset=%u", sreoff);
            return;
      }
      if (srelen & 3) {
            printf(" badlength=%u", srelen);
            return;
      }
      if (sreoff >= srelen) {
            printf(" badoff/len=%u/%u", sreoff, srelen);
            return;
      }

      for (;;) {
            if (len < 4 || srelen == 0)
                  return;

            memcpy(&a, bp, sizeof(a));
            printf(" %s%s",
                ((bp - up) == sreoff) ? "*" : "",
                inet_ntoa(a));

            bp += 4;
            len -= 4;
            srelen -= 4;
      }
}

void
gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
{
      const u_char *up = bp;

      if (sreoff & 1) {
            printf(" badoffset=%u", sreoff);
            return;
      }
      if (srelen & 1) {
            printf(" badlength=%u", srelen);
            return;
      }
      if (sreoff >= srelen) {
            printf(" badoff/len=%u/%u", sreoff, srelen);
            return;
      }

      for (;;) {
            if (len < 2 || srelen == 0)
                  return;

            printf(" %s%x",
                ((bp - up) == sreoff) ? "*" : "",
                EXTRACT_16BITS(bp));

            bp += 2;
            len -= 2;
            srelen -= 2;
      }
}

Generated by  Doxygen 1.6.0   Back to index