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 1.28 2005-04-06 21:32:39 mcr 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 static const char tstr[] = "[|gre]";
  61
  62 #define GRE_CP          0x8000          /* checksum present */
  63 #define GRE_RP          0x4000          /* routing present */
  64 #define GRE_KP          0x2000          /* key present */
  65 #define GRE_SP          0x1000          /* sequence# present */
  66 #define GRE_sP          0x0800          /* source routing */
  67 #define GRE_RECRS       0x0700          /* recursion count */
  68 #define GRE_AP          0x0080          /* acknowledgment# present */
  69
  70 static const struct tok gre_flag_values[] = {
  71     { GRE_CP, "checksum present"},
  72     { GRE_RP, "routing present"},
  73     { GRE_KP, "key present"},
  74     { GRE_SP, "sequence# present"},
  75     { GRE_sP, "source routing present"},
  76     { GRE_RECRS, "recursion count"},
  77     { GRE_AP, "ack present"},
  78     { 0, NULL }
  79 };
  80
  81 #define GRE_VERS_MASK   0x0007          /* protocol version */
  82
  83 /* source route entry types */
  84 #define GRESRE_IP       0x0800          /* IP */
  85 #define GRESRE_ASN      0xfffe          /* ASN */
  86
  87 void gre_print_0(const u_char *, u_int);
  88 void gre_print_1(const u_char *, u_int);
  89 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  90 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  91 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  92
  93 void
  94 gre_print(const u_char *bp, u_int length)
  95 {
  96         u_int len = length, vers;
  97
  98         if (len < 2) {
  99                 printf("%s", tstr);
 100                 return;
 101         }
 102         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
 103         printf("GREv%u",vers);
 104
 105         switch(vers) {
 106         case 0:
 107             gre_print_0(bp, len);
 108             break;
 109         case 1:
 110             gre_print_1(bp, len);
 111             break;
 112         default:
 113             printf(" ERROR: unknown-version");
 114             break;
 115         }
 116         return;
 117
 118 }
 119
 120 void
 121 gre_print_0(const u_char *bp, u_int length)
 122 {
 123         u_int len = length;
 124         u_int16_t flags, prot;
 125
 126         flags = EXTRACT_16BITS(bp);
 127         if (vflag)
 128             printf(", Flags [%s]",
 129                    bittok2str(gre_flag_values,"none",flags));
 130
 131         len -= 2;
 132         bp += 2;
 133
 134         if (len < 2)
 135                 goto trunc;
 136         prot = EXTRACT_16BITS(bp);
 137         len -= 2;
 138         bp += 2;
 139
 140         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 141                 if (len < 2)
 142                         goto trunc;
 143                 if (vflag)
 144                         printf(", sum 0x%x", EXTRACT_16BITS(bp));
 145                 bp += 2;
 146                 len -= 2;
 147
 148                 if (len < 2)
 149                         goto trunc;
 150                 printf(", off 0x%x", EXTRACT_16BITS(bp));
 151                 bp += 2;
 152                 len -= 2;
 153         }
 154
 155         if (flags & GRE_KP) {
 156                 if (len < 4)
 157                         goto trunc;
 158                 printf(", key=0x%x", EXTRACT_32BITS(bp));
 159                 bp += 4;
 160                 len -= 4;
 161         }
 162
 163         if (flags & GRE_SP) {
 164                 if (len < 4)
 165                         goto trunc;
 166                 printf(", seq %u", EXTRACT_32BITS(bp));
 167                 bp += 4;
 168                 len -= 4;
 169         }
 170
 171         if (flags & GRE_RP) {
 172                 for (;;) {
 173                         u_int16_t af;
 174                         u_int8_t sreoff;
 175                         u_int8_t srelen;
 176
 177                         if (len < 4)
 178                                 goto trunc;
 179                         af = EXTRACT_16BITS(bp);
 180                         sreoff = *(bp + 2);
 181                         srelen = *(bp + 3);
 182                         bp += 4;
 183                         len -= 4;
 184
 185                         if (af == 0 && srelen == 0)
 186                                 break;
 187
 188                         gre_sre_print(af, sreoff, srelen, bp, len);
 189
 190                         if (len < srelen)
 191                                 goto trunc;
 192                         bp += srelen;
 193                         len -= srelen;
 194                 }
 195         }
 196
 197         if (eflag)
 198             printf(", proto %s (0x%04x)",
 199                    tok2str(ethertype_values,"unknown",prot),
 200                    prot);
 201
 202         printf(", length %u",length);
 203
 204         if (vflag < 1)
 205             printf(": "); /* put in a colon as protocol demarc */
 206         else
 207             printf("\n\t"); /* if verbose go multiline */
 208
 209         switch (prot) {
 210         case ETHERTYPE_IP:
 211                 ip_print(gndo, bp, len);
 212                 break;
 213 #ifdef INET6
 214         case ETHERTYPE_IPV6:
 215                 ip6_print(gndo, bp, len);
 216                 break;
 217 #endif
 218         case ETHERTYPE_MPLS:
 219                 mpls_print(bp, len);
 220                 break;
 221         case ETHERTYPE_IPX:
 222                 ipx_print(bp, len);
 223                 break;
 224         case ETHERTYPE_ATALK:
 225                 atalk_print(bp, len);
 226                 break;
 227         case ETHERTYPE_GRE_ISO:
 228                 isoclns_print(bp, len, len);
 229                 break;
 230         case ETHERTYPE_TEB:
 231                 ether_print(gndo, bp, len, len, NULL, NULL);
 232                 break;
 233         default:
 234                 printf("gre-proto-0x%x", prot);
 235         }
 236         return;
 237
 238 trunc:
 239         printf("%s", tstr);
 240 }
 241
 242 void
 243 gre_print_1(const u_char *bp, u_int length)
 244 {
 245         u_int len = length;
 246         u_int16_t flags, prot;
 247
 248         flags = EXTRACT_16BITS(bp);
 249         len -= 2;
 250         bp += 2;
 251
 252         if (vflag)
 253             printf(", Flags [%s]",
 254                    bittok2str(gre_flag_values,"none",flags));
 255
 256         if (len < 2)
 257                 goto trunc;
 258         prot = EXTRACT_16BITS(bp);
 259         len -= 2;
 260         bp += 2;
 261
 262
 263         if (flags & GRE_KP) {
 264                 u_int32_t k;
 265
 266                 if (len < 4)
 267                         goto trunc;
 268                 k = EXTRACT_32BITS(bp);
 269                 printf(", call %d", k & 0xffff);
 270                 len -= 4;
 271                 bp += 4;
 272         }
 273
 274         if (flags & GRE_SP) {
 275                 if (len < 4)
 276                         goto trunc;
 277                 printf(", seq %u", EXTRACT_32BITS(bp));
 278                 bp += 4;
 279                 len -= 4;
 280         }
 281
 282         if (flags & GRE_AP) {
 283                 if (len < 4)
 284                         goto trunc;
 285                 printf(", ack %u", EXTRACT_32BITS(bp));
 286                 bp += 4;
 287                 len -= 4;
 288         }
 289
 290         if ((flags & GRE_SP) == 0)
 291                 printf(", no-payload");
 292
 293         if (eflag)
 294             printf(", proto %s (0x%04x)",
 295                    tok2str(ethertype_values,"unknown",prot),
 296                    prot);
 297
 298         printf(", length %u",length);
 299
 300         if ((flags & GRE_SP) == 0)
 301             return;
 302
 303         if (vflag < 1)
 304             printf(": "); /* put in a colon as protocol demarc */
 305         else
 306             printf("\n\t"); /* if verbose go multiline */
 307
 308         switch (prot) {
 309         case ETHERTYPE_PPP:
 310                 ppp_print(bp, len);
 311                 break;
 312         default:
 313                 printf("gre-proto-0x%x", prot);
 314                 break;
 315         }
 316         return;
 317
 318 trunc:
 319         printf("%s", tstr);
 320 }
 321
 322 void
 323 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 324     const u_char *bp, u_int len)
 325 {
 326         switch (af) {
 327         case GRESRE_IP:
 328                 printf(", (rtaf=ip");
 329                 gre_sre_ip_print(sreoff, srelen, bp, len);
 330                 printf(") ");
 331                 break;
 332         case GRESRE_ASN:
 333                 printf(", (rtaf=asn");
 334                 gre_sre_asn_print(sreoff, srelen, bp, len);
 335                 printf(") ");
 336                 break;
 337         default:
 338                 printf(", (rtaf=0x%x) ", af);
 339         }
 340 }
 341 void
 342 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 343 {
 344         struct in_addr a;
 345         const u_char *up = bp;
 346
 347         if (sreoff & 3) {
 348                 printf(", badoffset=%u", sreoff);
 349                 return;
 350         }
 351         if (srelen & 3) {
 352                 printf(", badlength=%u", srelen);
 353                 return;
 354         }
 355         if (sreoff >= srelen) {
 356                 printf(", badoff/len=%u/%u", sreoff, srelen);
 357                 return;
 358         }
 359
 360         for (;;) {
 361                 if (len < 4 || srelen == 0)
 362                         return;
 363
 364                 memcpy(&a, bp, sizeof(a));
 365                 printf(" %s%s",
 366                     ((bp - up) == sreoff) ? "*" : "",
 367                     inet_ntoa(a));
 368
 369                 bp += 4;
 370                 len -= 4;
 371                 srelen -= 4;
 372         }
 373 }
 374
 375 void
 376 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 377 {
 378         const u_char *up = bp;
 379
 380         if (sreoff & 1) {
 381                 printf(", badoffset=%u", sreoff);
 382                 return;
 383         }
 384         if (srelen & 1) {
 385                 printf(", badlength=%u", srelen);
 386                 return;
 387         }
 388         if (sreoff >= srelen) {
 389                 printf(", badoff/len=%u/%u", sreoff, srelen);
 390                 return;
 391         }
 392
 393         for (;;) {
 394                 if (len < 2 || srelen == 0)
 395                         return;
 396
 397                 printf(" %s%x",
 398                     ((bp - up) == sreoff) ? "*" : "",
 399                     EXTRACT_16BITS(bp));
 400
 401                 bp += 2;
 402                 len -= 2;
 403                 srelen -= 2;
 404         }
 405 }