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 /* \summary: Generic Routing Encapsulation (GRE) printer */
  35
  36 /*
  37  * netdissect printer for GRE - Generic Routing Encapsulation
  38  * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
  39  */
  40
  41 #ifdef HAVE_CONFIG_H
  42 #include "config.h"
  43 #endif
  44
  45 #include <netdissect-stdinc.h>
  46
  47 #include <string.h>
  48
  49 #include "netdissect.h"
  50 #include "addrtostr.h"
  51 #include "extract.h"
  52 #include "ethertype.h"
  53
  54 static const char tstr[] = "[|gre]";
  55
  56 #define GRE_CP          0x8000          /* checksum present */
  57 #define GRE_RP          0x4000          /* routing present */
  58 #define GRE_KP          0x2000          /* key present */
  59 #define GRE_SP          0x1000          /* sequence# present */
  60 #define GRE_sP          0x0800          /* source routing */
  61 #define GRE_RECRS       0x0700          /* recursion count */
  62 #define GRE_AP          0x0080          /* acknowledgment# present */
  63
  64 static const struct tok gre_flag_values[] = {
  65     { GRE_CP, "checksum present"},
  66     { GRE_RP, "routing present"},
  67     { GRE_KP, "key present"},
  68     { GRE_SP, "sequence# present"},
  69     { GRE_sP, "source routing present"},
  70     { GRE_RECRS, "recursion count"},
  71     { GRE_AP, "ack present"},
  72     { 0, NULL }
  73 };
  74
  75 #define GRE_VERS_MASK   0x0007          /* protocol version */
  76
  77 /* source route entry types */
  78 #define GRESRE_IP       0x0800          /* IP */
  79 #define GRESRE_ASN      0xfffe          /* ASN */
  80
  81 static void gre_print_0(netdissect_options *, const u_char *, u_int);
  82 static void gre_print_1(netdissect_options *, const u_char *, u_int);
  83 static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  84 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  85 static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  86
  87 void
  88 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
  89 {
  90         u_int len = length, vers;
  91
  92         ND_TCHECK2(*bp, 2);
  93         if (len < 2)
  94                 goto trunc;
  95         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
  96         ND_PRINT((ndo, "GREv%u",vers));
  97
  98         switch(vers) {
  99         case 0:
 100             gre_print_0(ndo, bp, len);
 101             break;
 102         case 1:
 103             gre_print_1(ndo, bp, len);
 104             break;
 105         default:
 106             ND_PRINT((ndo, " ERROR: unknown-version"));
 107             break;
 108         }
 109         return;
 110
 111 trunc:
 112         ND_PRINT((ndo, "%s", tstr));
 113         return;
 114 }
 115
 116 static void
 117 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 118 {
 119         u_int len = length;
 120         uint16_t flags, prot;
 121
 122         flags = EXTRACT_16BITS(bp);
 123         if (ndo->ndo_vflag)
 124             ND_PRINT((ndo, ", Flags [%s]",
 125                    bittok2str(gre_flag_values,"none",flags)));
 126
 127         len -= 2;
 128         bp += 2;
 129
 130         ND_TCHECK2(*bp, 2);
 131         if (len < 2)
 132                 goto trunc;
 133         prot = EXTRACT_16BITS(bp);
 134         len -= 2;
 135         bp += 2;
 136
 137         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 138                 ND_TCHECK2(*bp, 2);
 139                 if (len < 2)
 140                         goto trunc;
 141                 if (ndo->ndo_vflag)
 142                         ND_PRINT((ndo, ", sum 0x%x", EXTRACT_16BITS(bp)));
 143                 bp += 2;
 144                 len -= 2;
 145
 146                 ND_TCHECK2(*bp, 2);
 147                 if (len < 2)
 148                         goto trunc;
 149                 ND_PRINT((ndo, ", off 0x%x", EXTRACT_16BITS(bp)));
 150                 bp += 2;
 151                 len -= 2;
 152         }
 153
 154         if (flags & GRE_KP) {
 155                 ND_TCHECK2(*bp, 4);
 156                 if (len < 4)
 157                         goto trunc;
 158                 ND_PRINT((ndo, ", key=0x%x", EXTRACT_32BITS(bp)));
 159                 bp += 4;
 160                 len -= 4;
 161         }
 162
 163         if (flags & GRE_SP) {
 164                 ND_TCHECK2(*bp, 4);
 165                 if (len < 4)
 166                         goto trunc;
 167                 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
 168                 bp += 4;
 169                 len -= 4;
 170         }
 171
 172         if (flags & GRE_RP) {
 173                 for (;;) {
 174                         uint16_t af;
 175                         uint8_t sreoff;
 176                         uint8_t srelen;
 177
 178                         ND_TCHECK2(*bp, 4);
 179                         if (len < 4)
 180                                 goto trunc;
 181                         af = EXTRACT_16BITS(bp);
 182                         sreoff = *(bp + 2);
 183                         srelen = *(bp + 3);
 184                         bp += 4;
 185                         len -= 4;
 186
 187                         if (af == 0 && srelen == 0)
 188                                 break;
 189
 190                         if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
 191                                 goto trunc;
 192
 193                         if (len < srelen)
 194                                 goto trunc;
 195                         bp += srelen;
 196                         len -= srelen;
 197                 }
 198         }
 199
 200         if (ndo->ndo_eflag)
 201             ND_PRINT((ndo, ", proto %s (0x%04x)",
 202                    tok2str(ethertype_values,"unknown",prot),
 203                    prot));
 204
 205         ND_PRINT((ndo, ", length %u",length));
 206
 207         if (ndo->ndo_vflag < 1)
 208             ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
 209         else
 210             ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
 211
 212         switch (prot) {
 213         case ETHERTYPE_IP:
 214                 ip_print(ndo, bp, len);
 215                 break;
 216         case ETHERTYPE_IPV6:
 217                 ip6_print(ndo, bp, len);
 218                 break;
 219         case ETHERTYPE_MPLS:
 220                 mpls_print(ndo, bp, len);
 221                 break;
 222         case ETHERTYPE_IPX:
 223                 ipx_print(ndo, bp, len);
 224                 break;
 225         case ETHERTYPE_ATALK:
 226                 atalk_print(ndo, bp, len);
 227                 break;
 228         case ETHERTYPE_GRE_ISO:
 229                 isoclns_print(ndo, bp, len);
 230                 break;
 231         case ETHERTYPE_TEB:
 232                 ether_print(ndo, bp, len, ndo->ndo_snapend - bp, NULL, NULL);
 233                 break;
 234         default:
 235                 ND_PRINT((ndo, "gre-proto-0x%x", prot));
 236         }
 237         return;
 238
 239 trunc:
 240         ND_PRINT((ndo, "%s", tstr));
 241 }
 242
 243 static void
 244 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 245 {
 246         u_int len = length;
 247         uint16_t flags, prot;
 248
 249         flags = EXTRACT_16BITS(bp);
 250         len -= 2;
 251         bp += 2;
 252
 253         if (ndo->ndo_vflag)
 254             ND_PRINT((ndo, ", Flags [%s]",
 255                    bittok2str(gre_flag_values,"none",flags)));
 256
 257         ND_TCHECK2(*bp, 2);
 258         if (len < 2)
 259                 goto trunc;
 260         prot = EXTRACT_16BITS(bp);
 261         len -= 2;
 262         bp += 2;
 263
 264
 265         if (flags & GRE_KP) {
 266                 uint32_t k;
 267
 268                 ND_TCHECK2(*bp, 4);
 269                 if (len < 4)
 270                         goto trunc;
 271                 k = EXTRACT_32BITS(bp);
 272                 ND_PRINT((ndo, ", call %d", k & 0xffff));
 273                 len -= 4;
 274                 bp += 4;
 275         }
 276
 277         if (flags & GRE_SP) {
 278                 ND_TCHECK2(*bp, 4);
 279                 if (len < 4)
 280                         goto trunc;
 281                 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
 282                 bp += 4;
 283                 len -= 4;
 284         }
 285
 286         if (flags & GRE_AP) {
 287                 ND_TCHECK2(*bp, 4);
 288                 if (len < 4)
 289                         goto trunc;
 290                 ND_PRINT((ndo, ", ack %u", EXTRACT_32BITS(bp)));
 291                 bp += 4;
 292                 len -= 4;
 293         }
 294
 295         if ((flags & GRE_SP) == 0)
 296                 ND_PRINT((ndo, ", no-payload"));
 297
 298         if (ndo->ndo_eflag)
 299             ND_PRINT((ndo, ", proto %s (0x%04x)",
 300                    tok2str(ethertype_values,"unknown",prot),
 301                    prot));
 302
 303         ND_PRINT((ndo, ", length %u",length));
 304
 305         if ((flags & GRE_SP) == 0)
 306             return;
 307
 308         if (ndo->ndo_vflag < 1)
 309             ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
 310         else
 311             ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
 312
 313         switch (prot) {
 314         case ETHERTYPE_PPP:
 315                 ppp_print(ndo, bp, len);
 316                 break;
 317         default:
 318                 ND_PRINT((ndo, "gre-proto-0x%x", prot));
 319                 break;
 320         }
 321         return;
 322
 323 trunc:
 324         ND_PRINT((ndo, "%s", tstr));
 325 }
 326
 327 static int
 328 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 329     uint8_t srelen, const u_char *bp, u_int len)
 330 {
 331         int ret;
 332
 333         switch (af) {
 334         case GRESRE_IP:
 335                 ND_PRINT((ndo, ", (rtaf=ip"));
 336                 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 337                 ND_PRINT((ndo, ")"));
 338                 break;
 339         case GRESRE_ASN:
 340                 ND_PRINT((ndo, ", (rtaf=asn"));
 341                 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 342                 ND_PRINT((ndo, ")"));
 343                 break;
 344         default:
 345                 ND_PRINT((ndo, ", (rtaf=0x%x)", af));
 346                 ret = 1;
 347         }
 348         return (ret);
 349 }
 350
 351 static int
 352 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 353                  const u_char *bp, u_int len)
 354 {
 355         const u_char *up = bp;
 356         char buf[INET_ADDRSTRLEN];
 357
 358         if (sreoff & 3) {
 359                 ND_PRINT((ndo, ", badoffset=%u", sreoff));
 360                 return (1);
 361         }
 362         if (srelen & 3) {
 363                 ND_PRINT((ndo, ", badlength=%u", srelen));
 364                 return (1);
 365         }
 366         if (sreoff >= srelen) {
 367                 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
 368                 return (1);
 369         }
 370
 371         while (srelen != 0) {
 372                 if (!ND_TTEST2(*bp, 4))
 373                         return (0);
 374                 if (len < 4)
 375                         return (0);
 376
 377                 addrtostr(bp, buf, sizeof(buf));
 378                 ND_PRINT((ndo, " %s%s",
 379                     ((bp - up) == sreoff) ? "*" : "", buf));
 380
 381                 bp += 4;
 382                 len -= 4;
 383                 srelen -= 4;
 384         }
 385         return (1);
 386 }
 387
 388 static int
 389 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 390                   const u_char *bp, u_int len)
 391 {
 392         const u_char *up = bp;
 393
 394         if (sreoff & 1) {
 395                 ND_PRINT((ndo, ", badoffset=%u", sreoff));
 396                 return (1);
 397         }
 398         if (srelen & 1) {
 399                 ND_PRINT((ndo, ", badlength=%u", srelen));
 400                 return (1);
 401         }
 402         if (sreoff >= srelen) {
 403                 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
 404                 return (1);
 405         }
 406
 407         while (srelen != 0) {
 408                 if (!ND_TTEST2(*bp, 2))
 409                         return (0);
 410                 if (len < 2)
 411                         return (0);
 412
 413                 ND_PRINT((ndo, " %s%x",
 414                     ((bp - up) == sreoff) ? "*" : "",
 415                     EXTRACT_16BITS(bp)));
 416
 417                 bp += 2;
 418                 len -= 2;
 419                 srelen -= 2;
 420         }
 421         return (1);
 422 }