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  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  20  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  21  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  24  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  25  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  26  * POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /* \summary: Generic Routing Encapsulation (GRE) printer */
  30
  31 /*
  32  * netdissect printer for GRE - Generic Routing Encapsulation
  33  * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
  34  */
  35
  36 #include <config.h>
  37
  38 #include "netdissect-stdinc.h"
  39
  40 #include "netdissect.h"
  41 #include "addrtostr.h"
  42 #include "extract.h"
  43 #include "ethertype.h"
  44
  45
  46 #define GRE_CP          0x8000          /* checksum present */
  47 #define GRE_RP          0x4000          /* routing present */
  48 #define GRE_KP          0x2000          /* key present */
  49 #define GRE_SP          0x1000          /* sequence# present */
  50 #define GRE_sP          0x0800          /* source routing */
  51 #define GRE_AP          0x0080          /* acknowledgment# present */
  52
  53 static const struct tok gre_flag_values[] = {
  54     { GRE_CP, "checksum present"},
  55     { GRE_RP, "routing present"},
  56     { GRE_KP, "key present"},
  57     { GRE_SP, "sequence# present"},
  58     { GRE_sP, "source routing present"},
  59     { GRE_AP, "ack present"},
  60     { 0, NULL }
  61 };
  62
  63 #define GRE_RECRS_MASK  0x0700          /* recursion count */
  64 #define GRE_VERS_MASK   0x0007          /* protocol version */
  65
  66 /* source route entry types */
  67 #define GRESRE_IP       0x0800          /* IP */
  68 #define GRESRE_ASN      0xfffe          /* ASN */
  69
  70 static void gre_print_0(netdissect_options *, const u_char *, u_int);
  71 static void gre_print_1(netdissect_options *, const u_char *, u_int);
  72 static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  73 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  74 static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  75
  76 void
  77 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
  78 {
  79         u_int len = length, vers;
  80
  81         ndo->ndo_protocol = "gre";
  82         ND_TCHECK_2(bp);
  83         if (len < 2)
  84                 goto trunc;
  85         vers = GET_BE_U_2(bp) & GRE_VERS_MASK;
  86         ND_PRINT("GREv%u",vers);
  87
  88         switch(vers) {
  89         case 0:
  90                 gre_print_0(ndo, bp, len);
  91                 break;
  92         case 1:
  93                 gre_print_1(ndo, bp, len);
  94                 break;
  95         default:
  96                 ND_PRINT(" ERROR: unknown-version");
  97                 break;
  98         }
  99         return;
 100
 101 trunc:
 102         nd_print_trunc(ndo);
 103 }
 104
 105 static void
 106 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 107 {
 108         u_int len = length;
 109         uint16_t flags, prot;
 110
 111         /* 16 bits ND_TCHECKed in gre_print() */
 112         flags = GET_BE_U_2(bp);
 113         if (ndo->ndo_vflag)
 114                 ND_PRINT(", Flags [%s]",
 115                          bittok2str(gre_flag_values,"none",flags));
 116
 117         len -= 2;
 118         bp += 2;
 119
 120         ND_TCHECK_2(bp);
 121         if (len < 2)
 122                 goto trunc;
 123         prot = GET_BE_U_2(bp);
 124         len -= 2;
 125         bp += 2;
 126
 127         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 128                 ND_TCHECK_2(bp);
 129                 if (len < 2)
 130                         goto trunc;
 131                 if (ndo->ndo_vflag)
 132                         ND_PRINT(", sum 0x%x", GET_BE_U_2(bp));
 133                 bp += 2;
 134                 len -= 2;
 135
 136                 ND_TCHECK_2(bp);
 137                 if (len < 2)
 138                         goto trunc;
 139                 ND_PRINT(", off 0x%x", GET_BE_U_2(bp));
 140                 bp += 2;
 141                 len -= 2;
 142         }
 143
 144         if (flags & GRE_KP) {
 145                 ND_TCHECK_4(bp);
 146                 if (len < 4)
 147                         goto trunc;
 148                 ND_PRINT(", key=0x%x", GET_BE_U_4(bp));
 149                 bp += 4;
 150                 len -= 4;
 151         }
 152
 153         if (flags & GRE_SP) {
 154                 ND_TCHECK_4(bp);
 155                 if (len < 4)
 156                         goto trunc;
 157                 ND_PRINT(", seq %u", GET_BE_U_4(bp));
 158                 bp += 4;
 159                 len -= 4;
 160         }
 161
 162         if (flags & GRE_RP) {
 163                 for (;;) {
 164                         uint16_t af;
 165                         uint8_t sreoff;
 166                         uint8_t srelen;
 167
 168                         ND_TCHECK_4(bp);
 169                         if (len < 4)
 170                                 goto trunc;
 171                         af = GET_BE_U_2(bp);
 172                         sreoff = GET_U_1(bp + 2);
 173                         srelen = GET_U_1(bp + 3);
 174                         bp += 4;
 175                         len -= 4;
 176
 177                         if (af == 0 && srelen == 0)
 178                                 break;
 179
 180                         if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
 181                                 goto trunc;
 182
 183                         if (len < srelen)
 184                                 goto trunc;
 185                         bp += srelen;
 186                         len -= srelen;
 187                 }
 188         }
 189
 190         if (ndo->ndo_eflag)
 191                 ND_PRINT(", proto %s (0x%04x)",
 192                          tok2str(ethertype_values,"unknown",prot), prot);
 193
 194         ND_PRINT(", length %u",length);
 195
 196         if (ndo->ndo_vflag < 1)
 197                 ND_PRINT(": "); /* put in a colon as protocol demarc */
 198         else
 199                 ND_PRINT("\n\t"); /* if verbose go multiline */
 200
 201         switch (prot) {
 202         case ETHERTYPE_IP:
 203                 ip_print(ndo, bp, len);
 204                 break;
 205         case ETHERTYPE_IPV6:
 206                 ip6_print(ndo, bp, len);
 207                 break;
 208         case ETHERTYPE_MPLS:
 209                 mpls_print(ndo, bp, len);
 210                 break;
 211         case ETHERTYPE_IPX:
 212                 ipx_print(ndo, bp, len);
 213                 break;
 214         case ETHERTYPE_ATALK:
 215                 atalk_print(ndo, bp, len);
 216                 break;
 217         case ETHERTYPE_GRE_ISO:
 218                 isoclns_print(ndo, bp, len);
 219                 break;
 220         case ETHERTYPE_TEB:
 221                 ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
 222                 break;
 223         default:
 224                 ND_PRINT("gre-proto-0x%x", prot);
 225         }
 226         return;
 227
 228 trunc:
 229         nd_print_trunc(ndo);
 230 }
 231
 232 static void
 233 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 234 {
 235         u_int len = length;
 236         uint16_t flags, prot;
 237
 238         /* 16 bits ND_TCHECKed in gre_print() */
 239         flags = GET_BE_U_2(bp);
 240         len -= 2;
 241         bp += 2;
 242
 243         if (ndo->ndo_vflag)
 244                 ND_PRINT(", Flags [%s]",
 245                          bittok2str(gre_flag_values,"none",flags));
 246
 247         ND_TCHECK_2(bp);
 248         if (len < 2)
 249                 goto trunc;
 250         prot = GET_BE_U_2(bp);
 251         len -= 2;
 252         bp += 2;
 253
 254
 255         if (flags & GRE_KP) {
 256                 uint32_t k;
 257
 258                 ND_TCHECK_4(bp);
 259                 if (len < 4)
 260                         goto trunc;
 261                 k = GET_BE_U_4(bp);
 262                 ND_PRINT(", call %u", k & 0xffff);
 263                 len -= 4;
 264                 bp += 4;
 265         }
 266
 267         if (flags & GRE_SP) {
 268                 ND_TCHECK_4(bp);
 269                 if (len < 4)
 270                         goto trunc;
 271                 ND_PRINT(", seq %u", GET_BE_U_4(bp));
 272                 bp += 4;
 273                 len -= 4;
 274         }
 275
 276         if (flags & GRE_AP) {
 277                 ND_TCHECK_4(bp);
 278                 if (len < 4)
 279                         goto trunc;
 280                 ND_PRINT(", ack %u", GET_BE_U_4(bp));
 281                 bp += 4;
 282                 len -= 4;
 283         }
 284
 285         if ((flags & GRE_SP) == 0)
 286                 ND_PRINT(", no-payload");
 287
 288         if (ndo->ndo_eflag)
 289                 ND_PRINT(", proto %s (0x%04x)",
 290                          tok2str(ethertype_values,"unknown",prot), prot);
 291
 292         ND_PRINT(", length %u",length);
 293
 294         if ((flags & GRE_SP) == 0)
 295                 return;
 296
 297         if (ndo->ndo_vflag < 1)
 298                 ND_PRINT(": "); /* put in a colon as protocol demarc */
 299         else
 300                 ND_PRINT("\n\t"); /* if verbose go multiline */
 301
 302         switch (prot) {
 303         case ETHERTYPE_PPP:
 304                 ppp_print(ndo, bp, len);
 305                 break;
 306         default:
 307                 ND_PRINT("gre-proto-0x%x", prot);
 308                 break;
 309         }
 310         return;
 311
 312 trunc:
 313         nd_print_trunc(ndo);
 314 }
 315
 316 static int
 317 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 318               uint8_t srelen, const u_char *bp, u_int len)
 319 {
 320         int ret;
 321
 322         switch (af) {
 323         case GRESRE_IP:
 324                 ND_PRINT(", (rtaf=ip");
 325                 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 326                 ND_PRINT(")");
 327                 break;
 328         case GRESRE_ASN:
 329                 ND_PRINT(", (rtaf=asn");
 330                 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 331                 ND_PRINT(")");
 332                 break;
 333         default:
 334                 ND_PRINT(", (rtaf=0x%x)", af);
 335                 ret = 1;
 336         }
 337         return (ret);
 338 }
 339
 340 static int
 341 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 342                  const u_char *bp, u_int len)
 343 {
 344         const u_char *up = bp;
 345         char buf[INET_ADDRSTRLEN];
 346
 347         if (sreoff & 3) {
 348                 ND_PRINT(", badoffset=%u", sreoff);
 349                 return (1);
 350         }
 351         if (srelen & 3) {
 352                 ND_PRINT(", badlength=%u", srelen);
 353                 return (1);
 354         }
 355         if (sreoff >= srelen) {
 356                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 357                 return (1);
 358         }
 359
 360         while (srelen != 0) {
 361                 ND_TCHECK_4(bp);
 362                 if (len < 4)
 363                         return (0);
 364
 365                 addrtostr(bp, buf, sizeof(buf));
 366                 ND_PRINT(" %s%s",
 367                          ((bp - up) == sreoff) ? "*" : "", buf);
 368
 369                 bp += 4;
 370                 len -= 4;
 371                 srelen -= 4;
 372         }
 373         return (1);
 374 trunc:
 375         return 0;
 376 }
 377
 378 static int
 379 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 380                   const u_char *bp, u_int len)
 381 {
 382         const u_char *up = bp;
 383
 384         if (sreoff & 1) {
 385                 ND_PRINT(", badoffset=%u", sreoff);
 386                 return (1);
 387         }
 388         if (srelen & 1) {
 389                 ND_PRINT(", badlength=%u", srelen);
 390                 return (1);
 391         }
 392         if (sreoff >= srelen) {
 393                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 394                 return (1);
 395         }
 396
 397         while (srelen != 0) {
 398                 ND_TCHECK_2(bp);
 399                 if (len < 2)
 400                         return (0);
 401
 402                 ND_PRINT(" %s%x",
 403                          ((bp - up) == sreoff) ? "*" : "", GET_BE_U_2(bp));
 404
 405                 bp += 2;
 406                 len -= 2;
 407                 srelen -= 2;
 408         }
 409         return (1);
 410 trunc:
 411         return 0;
 412 }