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 #ifdef HAVE_CONFIG_H
  40 #include "config.h"
  41 #endif
  42
  43 #include <tcpdump-stdinc.h>
  44
  45 #include <stdio.h>
  46 #include <string.h>
  47
  48 #include "interface.h"
  49 #include "extract.h"
  50
  51 #include "ip.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 void gre_print_0(const u_char *, u_int);
  82 void gre_print_1(const u_char *, u_int);
  83 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  84 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  85 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  86
  87 void
  88 gre_print(const u_char *bp, u_int length)
  89 {
  90         u_int len = length, vers;
  91
  92         if (len < 2) {
  93                 printf("%s", tstr);
  94                 return;
  95         }
  96         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
  97         printf("GREv%u",vers);
  98
  99         switch(vers) {
 100         case 0:
 101             gre_print_0(bp, len);
 102             break;
 103         case 1:
 104             gre_print_1(bp, len);
 105             break;
 106         default:
 107             printf(" ERROR: unknown-version");
 108             break;
 109         }
 110         return;
 111
 112 }
 113
 114 void
 115 gre_print_0(const u_char *bp, u_int length)
 116 {
 117         u_int len = length;
 118         u_int16_t flags, prot;
 119
 120         flags = EXTRACT_16BITS(bp);
 121         if (vflag)
 122             printf(", Flags [%s]",
 123                    bittok2str(gre_flag_values,"none",flags));
 124
 125         len -= 2;
 126         bp += 2;
 127
 128         if (len < 2)
 129                 goto trunc;
 130         prot = EXTRACT_16BITS(bp);
 131         len -= 2;
 132         bp += 2;
 133
 134         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 135                 if (len < 2)
 136                         goto trunc;
 137                 if (vflag)
 138                         printf(", sum 0x%x", EXTRACT_16BITS(bp));
 139                 bp += 2;
 140                 len -= 2;
 141
 142                 if (len < 2)
 143                         goto trunc;
 144                 printf(", off 0x%x", EXTRACT_16BITS(bp));
 145                 bp += 2;
 146                 len -= 2;
 147         }
 148
 149         if (flags & GRE_KP) {
 150                 if (len < 4)
 151                         goto trunc;
 152                 printf(", key=0x%x", EXTRACT_32BITS(bp));
 153                 bp += 4;
 154                 len -= 4;
 155         }
 156
 157         if (flags & GRE_SP) {
 158                 if (len < 4)
 159                         goto trunc;
 160                 printf(", seq %u", EXTRACT_32BITS(bp));
 161                 bp += 4;
 162                 len -= 4;
 163         }
 164
 165         if (flags & GRE_RP) {
 166                 for (;;) {
 167                         u_int16_t af;
 168                         u_int8_t sreoff;
 169                         u_int8_t srelen;
 170
 171                         if (len < 4)
 172                                 goto trunc;
 173                         af = EXTRACT_16BITS(bp);
 174                         sreoff = *(bp + 2);
 175                         srelen = *(bp + 3);
 176                         bp += 4;
 177                         len -= 4;
 178
 179                         if (af == 0 && srelen == 0)
 180                                 break;
 181
 182                         gre_sre_print(af, sreoff, srelen, bp, len);
 183
 184                         if (len < srelen)
 185                                 goto trunc;
 186                         bp += srelen;
 187                         len -= srelen;
 188                 }
 189         }
 190
 191         if (eflag)
 192             printf(", proto %s (0x%04x)",
 193                    tok2str(ethertype_values,"unknown",prot),
 194                    prot);
 195
 196         printf(", length %u",length);
 197
 198         if (vflag < 1)
 199             printf(": "); /* put in a colon as protocol demarc */
 200         else
 201             printf("\n\t"); /* if verbose go multiline */
 202
 203         switch (prot) {
 204         case ETHERTYPE_IP:
 205                 ip_print(gndo, bp, len);
 206                 break;
 207 #ifdef INET6
 208         case ETHERTYPE_IPV6:
 209                 ip6_print(gndo, bp, len);
 210                 break;
 211 #endif
 212         case ETHERTYPE_MPLS:
 213                 mpls_print(bp, len);
 214                 break;
 215         case ETHERTYPE_IPX:
 216                 ipx_print(bp, len);
 217                 break;
 218         case ETHERTYPE_ATALK:
 219                 atalk_print(bp, len);
 220                 break;
 221         case ETHERTYPE_GRE_ISO:
 222                 isoclns_print(bp, len, len);
 223                 break;
 224         case ETHERTYPE_TEB:
 225                 ether_print(gndo, bp, len, len, NULL, NULL);
 226                 break;
 227         default:
 228                 printf("gre-proto-0x%x", prot);
 229         }
 230         return;
 231
 232 trunc:
 233         printf("%s", tstr);
 234 }
 235
 236 void
 237 gre_print_1(const u_char *bp, u_int length)
 238 {
 239         u_int len = length;
 240         u_int16_t flags, prot;
 241
 242         flags = EXTRACT_16BITS(bp);
 243         len -= 2;
 244         bp += 2;
 245
 246         if (vflag)
 247             printf(", Flags [%s]",
 248                    bittok2str(gre_flag_values,"none",flags));
 249
 250         if (len < 2)
 251                 goto trunc;
 252         prot = EXTRACT_16BITS(bp);
 253         len -= 2;
 254         bp += 2;
 255
 256
 257         if (flags & GRE_KP) {
 258                 u_int32_t k;
 259
 260                 if (len < 4)
 261                         goto trunc;
 262                 k = EXTRACT_32BITS(bp);
 263                 printf(", call %d", k & 0xffff);
 264                 len -= 4;
 265                 bp += 4;
 266         }
 267
 268         if (flags & GRE_SP) {
 269                 if (len < 4)
 270                         goto trunc;
 271                 printf(", seq %u", EXTRACT_32BITS(bp));
 272                 bp += 4;
 273                 len -= 4;
 274         }
 275
 276         if (flags & GRE_AP) {
 277                 if (len < 4)
 278                         goto trunc;
 279                 printf(", ack %u", EXTRACT_32BITS(bp));
 280                 bp += 4;
 281                 len -= 4;
 282         }
 283
 284         if ((flags & GRE_SP) == 0)
 285                 printf(", no-payload");
 286
 287         if (eflag)
 288             printf(", proto %s (0x%04x)",
 289                    tok2str(ethertype_values,"unknown",prot),
 290                    prot);
 291
 292         printf(", length %u",length);
 293
 294         if ((flags & GRE_SP) == 0)
 295             return;
 296
 297         if (vflag < 1)
 298             printf(": "); /* put in a colon as protocol demarc */
 299         else
 300             printf("\n\t"); /* if verbose go multiline */
 301
 302         switch (prot) {
 303         case ETHERTYPE_PPP:
 304                 ppp_print(bp, len);
 305                 break;
 306         default:
 307                 printf("gre-proto-0x%x", prot);
 308                 break;
 309         }
 310         return;
 311
 312 trunc:
 313         printf("%s", tstr);
 314 }
 315
 316 void
 317 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 318     const u_char *bp, u_int len)
 319 {
 320         switch (af) {
 321         case GRESRE_IP:
 322                 printf(", (rtaf=ip");
 323                 gre_sre_ip_print(sreoff, srelen, bp, len);
 324                 printf(") ");
 325                 break;
 326         case GRESRE_ASN:
 327                 printf(", (rtaf=asn");
 328                 gre_sre_asn_print(sreoff, srelen, bp, len);
 329                 printf(") ");
 330                 break;
 331         default:
 332                 printf(", (rtaf=0x%x) ", af);
 333         }
 334 }
 335 void
 336 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 337 {
 338         struct in_addr a;
 339         const u_char *up = bp;
 340
 341         if (sreoff & 3) {
 342                 printf(", badoffset=%u", sreoff);
 343                 return;
 344         }
 345         if (srelen & 3) {
 346                 printf(", badlength=%u", srelen);
 347                 return;
 348         }
 349         if (sreoff >= srelen) {
 350                 printf(", badoff/len=%u/%u", sreoff, srelen);
 351                 return;
 352         }
 353
 354         for (;;) {
 355                 if (len < 4 || srelen == 0)
 356                         return;
 357
 358                 memcpy(&a, bp, sizeof(a));
 359                 printf(" %s%s",
 360                     ((bp - up) == sreoff) ? "*" : "",
 361                     inet_ntoa(a));
 362
 363                 bp += 4;
 364                 len -= 4;
 365                 srelen -= 4;
 366         }
 367 }
 368
 369 void
 370 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 371 {
 372         const u_char *up = bp;
 373
 374         if (sreoff & 1) {
 375                 printf(", badoffset=%u", sreoff);
 376                 return;
 377         }
 378         if (srelen & 1) {
 379                 printf(", badlength=%u", srelen);
 380                 return;
 381         }
 382         if (sreoff >= srelen) {
 383                 printf(", badoff/len=%u/%u", sreoff, srelen);
 384                 return;
 385         }
 386
 387         for (;;) {
 388                 if (len < 2 || srelen == 0)
 389                         return;
 390
 391                 printf(" %s%x",
 392                     ((bp - up) == sreoff) ? "*" : "",
 393                     EXTRACT_16BITS(bp));
 394
 395                 bp += 2;
 396                 len -= 2;
 397                 srelen -= 2;
 398         }
 399 }