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 "addrtoname.h"
  50 #include "extract.h"
  51
  52 #include "ip.h"
  53 #include "ethertype.h"
  54
  55 static const char tstr[] = "[|gre]";
  56
  57 #define GRE_CP          0x8000          /* checksum present */
  58 #define GRE_RP          0x4000          /* routing present */
  59 #define GRE_KP          0x2000          /* key present */
  60 #define GRE_SP          0x1000          /* sequence# present */
  61 #define GRE_sP          0x0800          /* source routing */
  62 #define GRE_RECRS       0x0700          /* recursion count */
  63 #define GRE_AP          0x0080          /* acknowledgment# present */
  64
  65 static const struct tok gre_flag_values[] = {
  66     { GRE_CP, "checksum present"},
  67     { GRE_RP, "routing present"},
  68     { GRE_KP, "key present"},
  69     { GRE_SP, "sequence# present"},
  70     { GRE_sP, "source routing present"},
  71     { GRE_RECRS, "recursion count"},
  72     { GRE_AP, "ack present"},
  73     { 0, NULL }
  74 };
  75
  76 #define GRE_VERS_MASK   0x0007          /* protocol version */
  77
  78 /* source route entry types */
  79 #define GRESRE_IP       0x0800          /* IP */
  80 #define GRESRE_ASN      0xfffe          /* ASN */
  81
  82 void gre_print_0(const u_char *, u_int);
  83 void gre_print_1(const u_char *, u_int);
  84 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  85 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  86 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  87
  88 void
  89 gre_print(const u_char *bp, u_int length)
  90 {
  91         u_int len = length, vers;
  92
  93         if (len < 2) {
  94                 printf("%s", tstr);
  95                 return;
  96         }
  97         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
  98         printf("GREv%u",vers);
  99
 100         switch(vers) {
 101         case 0:
 102             gre_print_0(bp, len);
 103             break;
 104         case 1:
 105             gre_print_1(bp, len);
 106             break;
 107         default:
 108             printf(" ERROR: unknown-version");
 109             break;
 110         }
 111         return;
 112
 113 }
 114
 115 void
 116 gre_print_0(const u_char *bp, u_int length)
 117 {
 118         u_int len = length;
 119         u_int16_t flags, prot;
 120
 121         flags = EXTRACT_16BITS(bp);
 122         if (vflag)
 123             printf(", Flags [%s]",
 124                    bittok2str(gre_flag_values,"none",flags));
 125
 126         len -= 2;
 127         bp += 2;
 128
 129         if (len < 2)
 130                 goto trunc;
 131         prot = EXTRACT_16BITS(bp);
 132         len -= 2;
 133         bp += 2;
 134
 135         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 136                 if (len < 2)
 137                         goto trunc;
 138                 if (vflag)
 139                         printf(", sum 0x%x", EXTRACT_16BITS(bp));
 140                 bp += 2;
 141                 len -= 2;
 142
 143                 if (len < 2)
 144                         goto trunc;
 145                 printf(", off 0x%x", EXTRACT_16BITS(bp));
 146                 bp += 2;
 147                 len -= 2;
 148         }
 149
 150         if (flags & GRE_KP) {
 151                 if (len < 4)
 152                         goto trunc;
 153                 printf(", key=0x%x", EXTRACT_32BITS(bp));
 154                 bp += 4;
 155                 len -= 4;
 156         }
 157
 158         if (flags & GRE_SP) {
 159                 if (len < 4)
 160                         goto trunc;
 161                 printf(", seq %u", EXTRACT_32BITS(bp));
 162                 bp += 4;
 163                 len -= 4;
 164         }
 165
 166         if (flags & GRE_RP) {
 167                 for (;;) {
 168                         u_int16_t af;
 169                         u_int8_t sreoff;
 170                         u_int8_t srelen;
 171
 172                         if (len < 4)
 173                                 goto trunc;
 174                         af = EXTRACT_16BITS(bp);
 175                         sreoff = *(bp + 2);
 176                         srelen = *(bp + 3);
 177                         bp += 4;
 178                         len -= 4;
 179
 180                         if (af == 0 && srelen == 0)
 181                                 break;
 182
 183                         gre_sre_print(af, sreoff, srelen, bp, len);
 184
 185                         if (len < srelen)
 186                                 goto trunc;
 187                         bp += srelen;
 188                         len -= srelen;
 189                 }
 190         }
 191
 192         if (eflag)
 193             printf(", proto %s (0x%04x)",
 194                    tok2str(ethertype_values,"unknown",prot),
 195                    prot);
 196
 197         printf(", length %u",length);
 198
 199         if (vflag < 1)
 200             printf(": "); /* put in a colon as protocol demarc */
 201         else
 202             printf("\n\t"); /* if verbose go multiline */
 203
 204         switch (prot) {
 205         case ETHERTYPE_IP:
 206                 ip_print(gndo, bp, len);
 207                 break;
 208 #ifdef INET6
 209         case ETHERTYPE_IPV6:
 210                 ip6_print(gndo, bp, len);
 211                 break;
 212 #endif
 213         case ETHERTYPE_MPLS:
 214                 mpls_print(bp, len);
 215                 break;
 216         case ETHERTYPE_IPX:
 217                 ipx_print(bp, len);
 218                 break;
 219         case ETHERTYPE_ATALK:
 220                 atalk_print(bp, len);
 221                 break;
 222         case ETHERTYPE_GRE_ISO:
 223                 isoclns_print(bp, len, len);
 224                 break;
 225         case ETHERTYPE_TEB:
 226                 ether_print(gndo, bp, len, len, NULL, NULL);
 227                 break;
 228         default:
 229                 printf("gre-proto-0x%x", prot);
 230         }
 231         return;
 232
 233 trunc:
 234         printf("%s", tstr);
 235 }
 236
 237 void
 238 gre_print_1(const u_char *bp, u_int length)
 239 {
 240         u_int len = length;
 241         u_int16_t flags, prot;
 242
 243         flags = EXTRACT_16BITS(bp);
 244         len -= 2;
 245         bp += 2;
 246
 247         if (vflag)
 248             printf(", Flags [%s]",
 249                    bittok2str(gre_flag_values,"none",flags));
 250
 251         if (len < 2)
 252                 goto trunc;
 253         prot = EXTRACT_16BITS(bp);
 254         len -= 2;
 255         bp += 2;
 256
 257
 258         if (flags & GRE_KP) {
 259                 u_int32_t k;
 260
 261                 if (len < 4)
 262                         goto trunc;
 263                 k = EXTRACT_32BITS(bp);
 264                 printf(", call %d", k & 0xffff);
 265                 len -= 4;
 266                 bp += 4;
 267         }
 268
 269         if (flags & GRE_SP) {
 270                 if (len < 4)
 271                         goto trunc;
 272                 printf(", seq %u", EXTRACT_32BITS(bp));
 273                 bp += 4;
 274                 len -= 4;
 275         }
 276
 277         if (flags & GRE_AP) {
 278                 if (len < 4)
 279                         goto trunc;
 280                 printf(", ack %u", EXTRACT_32BITS(bp));
 281                 bp += 4;
 282                 len -= 4;
 283         }
 284
 285         if ((flags & GRE_SP) == 0)
 286                 printf(", no-payload");
 287
 288         if (eflag)
 289             printf(", proto %s (0x%04x)",
 290                    tok2str(ethertype_values,"unknown",prot),
 291                    prot);
 292
 293         printf(", length %u",length);
 294
 295         if ((flags & GRE_SP) == 0)
 296             return;
 297
 298         if (vflag < 1)
 299             printf(": "); /* put in a colon as protocol demarc */
 300         else
 301             printf("\n\t"); /* if verbose go multiline */
 302
 303         switch (prot) {
 304         case ETHERTYPE_PPP:
 305                 ppp_print(bp, len);
 306                 break;
 307         default:
 308                 printf("gre-proto-0x%x", prot);
 309                 break;
 310         }
 311         return;
 312
 313 trunc:
 314         printf("%s", tstr);
 315 }
 316
 317 void
 318 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 319     const u_char *bp, u_int len)
 320 {
 321         switch (af) {
 322         case GRESRE_IP:
 323                 printf(", (rtaf=ip");
 324                 gre_sre_ip_print(sreoff, srelen, bp, len);
 325                 printf(") ");
 326                 break;
 327         case GRESRE_ASN:
 328                 printf(", (rtaf=asn");
 329                 gre_sre_asn_print(sreoff, srelen, bp, len);
 330                 printf(") ");
 331                 break;
 332         default:
 333                 printf(", (rtaf=0x%x) ", af);
 334         }
 335 }
 336 void
 337 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 338 {
 339         struct in_addr a;
 340         const u_char *up = bp;
 341
 342         if (sreoff & 3) {
 343                 printf(", badoffset=%u", sreoff);
 344                 return;
 345         }
 346         if (srelen & 3) {
 347                 printf(", badlength=%u", srelen);
 348                 return;
 349         }
 350         if (sreoff >= srelen) {
 351                 printf(", badoff/len=%u/%u", sreoff, srelen);
 352                 return;
 353         }
 354
 355         for (;;) {
 356                 if (len < 4 || srelen == 0)
 357                         return;
 358
 359                 memcpy(&a, bp, sizeof(a));
 360                 printf(" %s%s",
 361                     ((bp - up) == sreoff) ? "*" : "",
 362                     inet_ntoa(a));
 363
 364                 bp += 4;
 365                 len -= 4;
 366                 srelen -= 4;
 367         }
 368 }
 369
 370 void
 371 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 372 {
 373         const u_char *up = bp;
 374
 375         if (sreoff & 1) {
 376                 printf(", badoffset=%u", sreoff);
 377                 return;
 378         }
 379         if (srelen & 1) {
 380                 printf(", badlength=%u", srelen);
 381                 return;
 382         }
 383         if (sreoff >= srelen) {
 384                 printf(", badoff/len=%u/%u", sreoff, srelen);
 385                 return;
 386         }
 387
 388         for (;;) {
 389                 if (len < 2 || srelen == 0)
 390                         return;
 391
 392                 printf(" %s%x",
 393                     ((bp - up) == sreoff) ? "*" : "",
 394                     EXTRACT_16BITS(bp));
 395
 396                 bp += 2;
 397                 len -= 2;
 398                 srelen -= 2;
 399         }
 400 }