The Tcpdump Group git mirrors - tcpdump/blob - print-gre.c

   1 /*      $OpenBSD: print-gre.c,v 1.6 2002/10/30 03:04:04 fgsch Exp $     */
   2
   3 /*
   4  * Copyright (c) 2002 Jason L. Wright (jason@thought.net)
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by Jason L. Wright
  18  * 4. The name of the author may not be used to endorse or promote products
  19  *    derived from this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  24  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  25  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  26  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  27  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  29  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  30  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * tcpdump filter for GRE - Generic Routing Encapsulation
  36  * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
  37  */
  38
  39 #ifndef lint
  40 static const char rcsid[] _U_ =
  41     "@(#) $Header: /tcpdump/master/tcpdump/print-gre.c,v 1.25 2004-06-12 16:32:56 hannes Exp $ (LBL)";
  42 #endif
  43
  44 #ifdef HAVE_CONFIG_H
  45 #include "config.h"
  46 #endif
  47
  48 #include <tcpdump-stdinc.h>
  49
  50 #include <stdio.h>
  51 #include <string.h>
  52
  53 #include "interface.h"
  54 #include "addrtoname.h"
  55 #include "extract.h"
  56
  57 #include "ip.h"
  58 #include "ethertype.h"
  59
  60 #define GRE_CP          0x8000          /* checksum present */
  61 #define GRE_RP          0x4000          /* routing present */
  62 #define GRE_KP          0x2000          /* key present */
  63 #define GRE_SP          0x1000          /* sequence# present */
  64 #define GRE_sP          0x0800          /* source routing */
  65 #define GRE_RECRS       0x0700          /* recursion count */
  66 #define GRE_AP          0x0080          /* acknowledgment# present */
  67 #define GRE_VERS_MASK   0x0007          /* protocol version */
  68
  69 /* source route entry types */
  70 #define GRESRE_IP       0x0800          /* IP */
  71 #define GRESRE_ASN      0xfffe          /* ASN */
  72
  73 void gre_print_0(const u_char *, u_int);
  74 void gre_print_1(const u_char *, u_int);
  75 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  76 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  77 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  78
  79 void
  80 gre_print(const u_char *bp, u_int length)
  81 {
  82         u_int len = length, vers;
  83
  84         if (len < 2) {
  85                 printf("[|gre]");
  86                 return;
  87         }
  88         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
  89         printf("GREv%u",vers);
  90
  91         switch(vers) {
  92         case 0:
  93             gre_print_0(bp, len);
  94             break;
  95         case 1:
  96             gre_print_1(bp, len);
  97             break;
  98         default:
  99             printf(" ERROR: unknown-version");
 100             break;
 101         }
 102         return;
 103
 104 }
 105
 106 void
 107 gre_print_0(const u_char *bp, u_int length)
 108 {
 109         u_int len = length;
 110         u_int16_t flags, prot;
 111
 112         flags = EXTRACT_16BITS(bp);
 113         if (vflag && flags) {
 114                 printf("[%s%s%s%s%s] ",
 115                     (flags & GRE_CP) ? "C" : "",
 116                     (flags & GRE_RP) ? "R" : "",
 117                     (flags & GRE_KP) ? "K" : "",
 118                     (flags & GRE_SP) ? "S" : "",
 119                     (flags & GRE_sP) ? "s" : "");
 120         }
 121
 122         len -= 2;
 123         bp += 2;
 124
 125         if (len < 2)
 126                 goto trunc;
 127         prot = EXTRACT_16BITS(bp);
 128         len -= 2;
 129         bp += 2;
 130
 131         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 132                 if (len < 2)
 133                         goto trunc;
 134                 if (vflag)
 135                         printf("sum 0x%x ", EXTRACT_16BITS(bp));
 136                 bp += 2;
 137                 len -= 2;
 138
 139                 if (len < 2)
 140                         goto trunc;
 141                 printf("off 0x%x ", EXTRACT_16BITS(bp));
 142                 bp += 2;
 143                 len -= 2;
 144         }
 145
 146         if (flags & GRE_KP) {
 147                 if (len < 4)
 148                         goto trunc;
 149                 printf("key=0x%x ", EXTRACT_32BITS(bp));
 150                 bp += 4;
 151                 len -= 4;
 152         }
 153
 154         if (flags & GRE_SP) {
 155                 if (len < 4)
 156                         goto trunc;
 157                 printf("seq %u ", EXTRACT_32BITS(bp));
 158                 bp += 4;
 159                 len -= 4;
 160         }
 161
 162         if (flags & GRE_RP) {
 163                 for (;;) {
 164                         u_int16_t af;
 165                         u_int8_t sreoff;
 166                         u_int8_t srelen;
 167
 168                         if (len < 4)
 169                                 goto trunc;
 170                         af = EXTRACT_16BITS(bp);
 171                         sreoff = *(bp + 2);
 172                         srelen = *(bp + 3);
 173                         bp += 4;
 174                         len -= 4;
 175
 176                         if (af == 0 && srelen == 0)
 177                                 break;
 178
 179                         gre_sre_print(af, sreoff, srelen, bp, len);
 180
 181                         if (len < srelen)
 182                                 goto trunc;
 183                         bp += srelen;
 184                         len -= srelen;
 185                 }
 186         }
 187
 188         if (eflag)
 189             printf(", proto %s (0x%04x)",
 190                    tok2str(ethertype_values,"unknown",prot),
 191                    prot);
 192         printf(": ");
 193
 194         switch (prot) {
 195         case ETHERTYPE_IP:
 196                 ip_print(bp, len);
 197                 break;
 198         case ETHERTYPE_IPV6:
 199                 ip6_print(bp, len);
 200                 break;
 201         case ETHERTYPE_MPLS:
 202                 mpls_print(bp, len);
 203                 break;
 204         case ETHERTYPE_IPX:
 205                 ipx_print(bp, len);
 206                 break;
 207         case ETHERTYPE_ATALK:
 208                 atalk_print(bp, len);
 209                 break;
 210         case ETHERTYPE_GRE_ISO:
 211                 isoclns_print(bp, len, len);
 212                 break;
 213         default:
 214                 printf("gre-proto-0x%x", prot);
 215         }
 216         return;
 217
 218 trunc:
 219         printf("[|gre]");
 220 }
 221
 222 void
 223 gre_print_1(const u_char *bp, u_int length)
 224 {
 225         u_int len = length;
 226         u_int16_t flags, prot;
 227
 228         flags = EXTRACT_16BITS(bp);
 229         len -= 2;
 230         bp += 2;
 231
 232         if (vflag) {
 233                 printf("[%s%s%s%s%s%s] ",
 234                     (flags & GRE_CP) ? "C" : "",
 235                     (flags & GRE_RP) ? "R" : "",
 236                     (flags & GRE_KP) ? "K" : "",
 237                     (flags & GRE_SP) ? "S" : "",
 238                     (flags & GRE_sP) ? "s" : "",
 239                     (flags & GRE_AP) ? "A" : "");
 240         }
 241
 242         if (len < 2)
 243                 goto trunc;
 244         prot = EXTRACT_16BITS(bp);
 245         len -= 2;
 246         bp += 2;
 247
 248         if (flags & GRE_CP) {
 249                 printf("cpset!");
 250                 return;
 251         }
 252         if (flags & GRE_RP) {
 253                 printf("rpset!");
 254                 return;
 255         }
 256         if ((flags & GRE_KP) == 0) {
 257                 printf("kpunset!");
 258                 return;
 259         }
 260         if (flags & GRE_sP) {
 261                 printf("spset!");
 262                 return;
 263         }
 264
 265         if (flags & GRE_KP) {
 266                 u_int32_t k;
 267
 268                 if (len < 4)
 269                         goto trunc;
 270                 k = EXTRACT_32BITS(bp);
 271                 printf("call %d ", k & 0xffff);
 272                 len -= 4;
 273                 bp += 4;
 274         }
 275
 276         if (flags & GRE_SP) {
 277                 if (len < 4)
 278                         goto trunc;
 279                 printf("seq %u ", EXTRACT_32BITS(bp));
 280                 bp += 4;
 281                 len -= 4;
 282         }
 283
 284         if (flags & GRE_AP) {
 285                 if (len < 4)
 286                         goto trunc;
 287                 printf("ack %u ", EXTRACT_32BITS(bp));
 288                 bp += 4;
 289                 len -= 4;
 290         }
 291
 292         if ((flags & GRE_SP) == 0) {
 293                 printf("no-payload");
 294                 return;
 295         }
 296
 297         switch (prot) {
 298         case ETHERTYPE_PPP:
 299                 printf("gre-ppp-payload");
 300                 break;
 301         default:
 302                 printf("gre-proto-0x%x", prot);
 303                 break;
 304         }
 305         return;
 306
 307 trunc:
 308         printf("[|gre]");
 309 }
 310
 311 void
 312 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 313     const u_char *bp, u_int len)
 314 {
 315         switch (af) {
 316         case GRESRE_IP:
 317                 printf("(rtaf=ip");
 318                 gre_sre_ip_print(sreoff, srelen, bp, len);
 319                 printf(") ");
 320                 break;
 321         case GRESRE_ASN:
 322                 printf("(rtaf=asn");
 323                 gre_sre_asn_print(sreoff, srelen, bp, len);
 324                 printf(") ");
 325                 break;
 326         default:
 327                 printf("(rtaf=0x%x) ", af);
 328         }
 329 }
 330 void
 331 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 332 {
 333         struct in_addr a;
 334         const u_char *up = bp;
 335
 336         if (sreoff & 3) {
 337                 printf(" badoffset=%u", sreoff);
 338                 return;
 339         }
 340         if (srelen & 3) {
 341                 printf(" badlength=%u", srelen);
 342                 return;
 343         }
 344         if (sreoff >= srelen) {
 345                 printf(" badoff/len=%u/%u", sreoff, srelen);
 346                 return;
 347         }
 348
 349         for (;;) {
 350                 if (len < 4 || srelen == 0)
 351                         return;
 352
 353                 memcpy(&a, bp, sizeof(a));
 354                 printf(" %s%s",
 355                     ((bp - up) == sreoff) ? "*" : "",
 356                     inet_ntoa(a));
 357
 358                 bp += 4;
 359                 len -= 4;
 360                 srelen -= 4;
 361         }
 362 }
 363
 364 void
 365 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 366 {
 367         const u_char *up = bp;
 368
 369         if (sreoff & 1) {
 370                 printf(" badoffset=%u", sreoff);
 371                 return;
 372         }
 373         if (srelen & 1) {
 374                 printf(" badlength=%u", srelen);
 375                 return;
 376         }
 377         if (sreoff >= srelen) {
 378                 printf(" badoff/len=%u/%u", sreoff, srelen);
 379                 return;
 380         }
 381
 382         for (;;) {
 383                 if (len < 2 || srelen == 0)
 384                         return;
 385
 386                 printf(" %s%x",
 387                     ((bp - up) == sreoff) ? "*" : "",
 388                     EXTRACT_16BITS(bp));
 389
 390                 bp += 2;
 391                 len -= 2;
 392                 srelen -= 2;
 393         }
 394 }