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 #ifdef HAVE_CONFIG_H
  37 #include <config.h>
  38 #endif
  39
  40 #include "netdissect-stdinc.h"
  41
  42 #include "netdissect.h"
  43 #include "addrtostr.h"
  44 #include "extract.h"
  45 #include "ethertype.h"
  46
  47
  48 #define GRE_CP          0x8000          /* checksum present */
  49 #define GRE_RP          0x4000          /* routing present */
  50 #define GRE_KP          0x2000          /* key present */
  51 #define GRE_SP          0x1000          /* sequence# present */
  52 #define GRE_sP          0x0800          /* source routing */
  53 #define GRE_AP          0x0080          /* acknowledgment# present */
  54
  55 static const struct tok gre_flag_values[] = {
  56     { GRE_CP, "checksum present"},
  57     { GRE_RP, "routing present"},
  58     { GRE_KP, "key present"},
  59     { GRE_SP, "sequence# present"},
  60     { GRE_sP, "source routing present"},
  61     { GRE_AP, "ack present"},
  62     { 0, NULL }
  63 };
  64
  65 #define GRE_RECRS_MASK  0x0700          /* recursion count */
  66 #define GRE_VERS_MASK   0x0007          /* protocol version */
  67
  68 /* source route entry types */
  69 #define GRESRE_IP       0x0800          /* IP */
  70 #define GRESRE_ASN      0xfffe          /* ASN */
  71
  72 static void gre_print_0(netdissect_options *, const u_char *, u_int);
  73 static void gre_print_1(netdissect_options *, const u_char *, u_int);
  74 static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  75 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  76 static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  77
  78 void
  79 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
  80 {
  81         u_int len = length, vers;
  82
  83         ndo->ndo_protocol = "gre";
  84         ND_TCHECK_2(bp);
  85         if (len < 2)
  86                 goto trunc;
  87         vers = GET_BE_U_2(bp) & GRE_VERS_MASK;
  88         ND_PRINT("GREv%u",vers);
  89
  90         switch(vers) {
  91         case 0:
  92                 gre_print_0(ndo, bp, len);
  93                 break;
  94         case 1:
  95                 gre_print_1(ndo, bp, len);
  96                 break;
  97         default:
  98                 ND_PRINT(" ERROR: unknown-version");
  99                 break;
 100         }
 101         return;
 102
 103 trunc:
 104         nd_print_trunc(ndo);
 105 }
 106
 107 static void
 108 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 109 {
 110         u_int len = length;
 111         uint16_t flags, prot;
 112
 113         /* 16 bits ND_TCHECKed in gre_print() */
 114         flags = GET_BE_U_2(bp);
 115         if (ndo->ndo_vflag)
 116                 ND_PRINT(", Flags [%s]",
 117                          bittok2str(gre_flag_values,"none",flags));
 118
 119         len -= 2;
 120         bp += 2;
 121
 122         ND_TCHECK_2(bp);
 123         if (len < 2)
 124                 goto trunc;
 125         prot = GET_BE_U_2(bp);
 126         len -= 2;
 127         bp += 2;
 128
 129         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 130                 ND_TCHECK_2(bp);
 131                 if (len < 2)
 132                         goto trunc;
 133                 if (ndo->ndo_vflag)
 134                         ND_PRINT(", sum 0x%x", GET_BE_U_2(bp));
 135                 bp += 2;
 136                 len -= 2;
 137
 138                 ND_TCHECK_2(bp);
 139                 if (len < 2)
 140                         goto trunc;
 141                 ND_PRINT(", off 0x%x", GET_BE_U_2(bp));
 142                 bp += 2;
 143                 len -= 2;
 144         }
 145
 146         if (flags & GRE_KP) {
 147                 ND_TCHECK_4(bp);
 148                 if (len < 4)
 149                         goto trunc;
 150                 ND_PRINT(", key=0x%x", GET_BE_U_4(bp));
 151                 bp += 4;
 152                 len -= 4;
 153         }
 154
 155         if (flags & GRE_SP) {
 156                 ND_TCHECK_4(bp);
 157                 if (len < 4)
 158                         goto trunc;
 159                 ND_PRINT(", seq %u", GET_BE_U_4(bp));
 160                 bp += 4;
 161                 len -= 4;
 162         }
 163
 164         if (flags & GRE_RP) {
 165                 for (;;) {
 166                         uint16_t af;
 167                         uint8_t sreoff;
 168                         uint8_t srelen;
 169
 170                         ND_TCHECK_4(bp);
 171                         if (len < 4)
 172                                 goto trunc;
 173                         af = GET_BE_U_2(bp);
 174                         sreoff = GET_U_1(bp + 2);
 175                         srelen = GET_U_1(bp + 3);
 176                         bp += 4;
 177                         len -= 4;
 178
 179                         if (af == 0 && srelen == 0)
 180                                 break;
 181
 182                         if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
 183                                 goto trunc;
 184
 185                         if (len < srelen)
 186                                 goto trunc;
 187                         bp += srelen;
 188                         len -= srelen;
 189                 }
 190         }
 191
 192         if (ndo->ndo_eflag)
 193                 ND_PRINT(", proto %s (0x%04x)",
 194                          tok2str(ethertype_values,"unknown",prot), prot);
 195
 196         ND_PRINT(", length %u",length);
 197
 198         if (ndo->ndo_vflag < 1)
 199                 ND_PRINT(": "); /* put in a colon as protocol demarc */
 200         else
 201                 ND_PRINT("\n\t"); /* if verbose go multiline */
 202
 203         switch (prot) {
 204         case ETHERTYPE_IP:
 205                 ip_print(ndo, bp, len);
 206                 break;
 207         case ETHERTYPE_IPV6:
 208                 ip6_print(ndo, bp, len);
 209                 break;
 210         case ETHERTYPE_MPLS:
 211                 mpls_print(ndo, bp, len);
 212                 break;
 213         case ETHERTYPE_IPX:
 214                 ipx_print(ndo, bp, len);
 215                 break;
 216         case ETHERTYPE_ATALK:
 217                 atalk_print(ndo, bp, len);
 218                 break;
 219         case ETHERTYPE_GRE_ISO:
 220                 isoclns_print(ndo, bp, len);
 221                 break;
 222         case ETHERTYPE_TEB:
 223                 ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
 224                 break;
 225         default:
 226                 ND_PRINT("gre-proto-0x%x", prot);
 227         }
 228         return;
 229
 230 trunc:
 231         nd_print_trunc(ndo);
 232 }
 233
 234 static void
 235 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 236 {
 237         u_int len = length;
 238         uint16_t flags, prot;
 239
 240         /* 16 bits ND_TCHECKed in gre_print() */
 241         flags = GET_BE_U_2(bp);
 242         len -= 2;
 243         bp += 2;
 244
 245         if (ndo->ndo_vflag)
 246                 ND_PRINT(", Flags [%s]",
 247                          bittok2str(gre_flag_values,"none",flags));
 248
 249         ND_TCHECK_2(bp);
 250         if (len < 2)
 251                 goto trunc;
 252         prot = GET_BE_U_2(bp);
 253         len -= 2;
 254         bp += 2;
 255
 256
 257         if (flags & GRE_KP) {
 258                 uint32_t k;
 259
 260                 ND_TCHECK_4(bp);
 261                 if (len < 4)
 262                         goto trunc;
 263                 k = GET_BE_U_4(bp);
 264                 ND_PRINT(", call %u", k & 0xffff);
 265                 len -= 4;
 266                 bp += 4;
 267         }
 268
 269         if (flags & GRE_SP) {
 270                 ND_TCHECK_4(bp);
 271                 if (len < 4)
 272                         goto trunc;
 273                 ND_PRINT(", seq %u", GET_BE_U_4(bp));
 274                 bp += 4;
 275                 len -= 4;
 276         }
 277
 278         if (flags & GRE_AP) {
 279                 ND_TCHECK_4(bp);
 280                 if (len < 4)
 281                         goto trunc;
 282                 ND_PRINT(", ack %u", GET_BE_U_4(bp));
 283                 bp += 4;
 284                 len -= 4;
 285         }
 286
 287         if ((flags & GRE_SP) == 0)
 288                 ND_PRINT(", no-payload");
 289
 290         if (ndo->ndo_eflag)
 291                 ND_PRINT(", proto %s (0x%04x)",
 292                          tok2str(ethertype_values,"unknown",prot), prot);
 293
 294         ND_PRINT(", length %u",length);
 295
 296         if ((flags & GRE_SP) == 0)
 297                 return;
 298
 299         if (ndo->ndo_vflag < 1)
 300                 ND_PRINT(": "); /* put in a colon as protocol demarc */
 301         else
 302                 ND_PRINT("\n\t"); /* if verbose go multiline */
 303
 304         switch (prot) {
 305         case ETHERTYPE_PPP:
 306                 ppp_print(ndo, bp, len);
 307                 break;
 308         default:
 309                 ND_PRINT("gre-proto-0x%x", prot);
 310                 break;
 311         }
 312         return;
 313
 314 trunc:
 315         nd_print_trunc(ndo);
 316 }
 317
 318 static int
 319 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 320               uint8_t srelen, const u_char *bp, u_int len)
 321 {
 322         int ret;
 323
 324         switch (af) {
 325         case GRESRE_IP:
 326                 ND_PRINT(", (rtaf=ip");
 327                 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 328                 ND_PRINT(")");
 329                 break;
 330         case GRESRE_ASN:
 331                 ND_PRINT(", (rtaf=asn");
 332                 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 333                 ND_PRINT(")");
 334                 break;
 335         default:
 336                 ND_PRINT(", (rtaf=0x%x)", af);
 337                 ret = 1;
 338         }
 339         return (ret);
 340 }
 341
 342 static int
 343 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 344                  const u_char *bp, u_int len)
 345 {
 346         const u_char *up = bp;
 347         char buf[INET_ADDRSTRLEN];
 348
 349         if (sreoff & 3) {
 350                 ND_PRINT(", badoffset=%u", sreoff);
 351                 return (1);
 352         }
 353         if (srelen & 3) {
 354                 ND_PRINT(", badlength=%u", srelen);
 355                 return (1);
 356         }
 357         if (sreoff >= srelen) {
 358                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 359                 return (1);
 360         }
 361
 362         while (srelen != 0) {
 363                 ND_TCHECK_4(bp);
 364                 if (len < 4)
 365                         return (0);
 366
 367                 addrtostr(bp, buf, sizeof(buf));
 368                 ND_PRINT(" %s%s",
 369                          ((bp - up) == sreoff) ? "*" : "", buf);
 370
 371                 bp += 4;
 372                 len -= 4;
 373                 srelen -= 4;
 374         }
 375         return (1);
 376 trunc:
 377         return 0;
 378 }
 379
 380 static int
 381 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 382                   const u_char *bp, u_int len)
 383 {
 384         const u_char *up = bp;
 385
 386         if (sreoff & 1) {
 387                 ND_PRINT(", badoffset=%u", sreoff);
 388                 return (1);
 389         }
 390         if (srelen & 1) {
 391                 ND_PRINT(", badlength=%u", srelen);
 392                 return (1);
 393         }
 394         if (sreoff >= srelen) {
 395                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 396                 return (1);
 397         }
 398
 399         while (srelen != 0) {
 400                 ND_TCHECK_2(bp);
 401                 if (len < 2)
 402                         return (0);
 403
 404                 ND_PRINT(" %s%x",
 405                          ((bp - up) == sreoff) ? "*" : "", GET_BE_U_2(bp));
 406
 407                 bp += 2;
 408                 len -= 2;
 409                 srelen -= 2;
 410         }
 411         return (1);
 412 trunc:
 413         return 0;
 414 }