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 1.26 2004-06-29 08:12:06 hannes 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 #define GRE_CP          0x8000          /* checksum present */
  61 #define GRE_RP          0x4000          /* routing present */
  62 #define GRE_KP          0x2000          /* key present */
  63 #define GRE_SP          0x1000          /* sequence# present */
  64 #define GRE_sP          0x0800          /* source routing */
  65 #define GRE_RECRS       0x0700          /* recursion count */
  66 #define GRE_AP          0x0080          /* acknowledgment# present */
  67
  68 struct tok gre_flag_values[] = {
  69     { GRE_CP, "checksum present"},
  70     { GRE_RP, "routing present"},
  71     { GRE_KP, "key present"},
  72     { GRE_SP, "sequence# present"},
  73     { GRE_sP, "source routing present"},
  74     { GRE_RECRS, "recursion count"},
  75     { GRE_AP, "ack present"},
  76     { 0, NULL }
  77 };
  78
  79 #define GRE_VERS_MASK   0x0007          /* protocol version */
  80
  81 /* source route entry types */
  82 #define GRESRE_IP       0x0800          /* IP */
  83 #define GRESRE_ASN      0xfffe          /* ASN */
  84
  85 void gre_print_0(const u_char *, u_int);
  86 void gre_print_1(const u_char *, u_int);
  87 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  88 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  89 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  90
  91 void
  92 gre_print(const u_char *bp, u_int length)
  93 {
  94         u_int len = length, vers;
  95
  96         if (len < 2) {
  97                 printf("[|gre]");
  98                 return;
  99         }
 100         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
 101         printf("GREv%u",vers);
 102
 103         switch(vers) {
 104         case 0:
 105             gre_print_0(bp, len);
 106             break;
 107         case 1:
 108             gre_print_1(bp, len);
 109             break;
 110         default:
 111             printf(" ERROR: unknown-version");
 112             break;
 113         }
 114         return;
 115
 116 }
 117
 118 void
 119 gre_print_0(const u_char *bp, u_int length)
 120 {
 121         u_int len = length;
 122         u_int16_t flags, prot;
 123
 124         flags = EXTRACT_16BITS(bp);
 125         if (vflag)
 126             printf(", Flags [%s]",
 127                    bittok2str(gre_flag_values,"none",flags));
 128
 129         len -= 2;
 130         bp += 2;
 131
 132         if (len < 2)
 133                 goto trunc;
 134         prot = EXTRACT_16BITS(bp);
 135         len -= 2;
 136         bp += 2;
 137
 138         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 139                 if (len < 2)
 140                         goto trunc;
 141                 if (vflag)
 142                         printf(", sum 0x%x", EXTRACT_16BITS(bp));
 143                 bp += 2;
 144                 len -= 2;
 145
 146                 if (len < 2)
 147                         goto trunc;
 148                 printf(", off 0x%x", EXTRACT_16BITS(bp));
 149                 bp += 2;
 150                 len -= 2;
 151         }
 152
 153         if (flags & GRE_KP) {
 154                 if (len < 4)
 155                         goto trunc;
 156                 printf(", key=0x%x", EXTRACT_32BITS(bp));
 157                 bp += 4;
 158                 len -= 4;
 159         }
 160
 161         if (flags & GRE_SP) {
 162                 if (len < 4)
 163                         goto trunc;
 164                 printf(", seq %u", EXTRACT_32BITS(bp));
 165                 bp += 4;
 166                 len -= 4;
 167         }
 168
 169         if (flags & GRE_RP) {
 170                 for (;;) {
 171                         u_int16_t af;
 172                         u_int8_t sreoff;
 173                         u_int8_t srelen;
 174
 175                         if (len < 4)
 176                                 goto trunc;
 177                         af = EXTRACT_16BITS(bp);
 178                         sreoff = *(bp + 2);
 179                         srelen = *(bp + 3);
 180                         bp += 4;
 181                         len -= 4;
 182
 183                         if (af == 0 && srelen == 0)
 184                                 break;
 185
 186                         gre_sre_print(af, sreoff, srelen, bp, len);
 187
 188                         if (len < srelen)
 189                                 goto trunc;
 190                         bp += srelen;
 191                         len -= srelen;
 192                 }
 193         }
 194
 195         if (eflag)
 196             printf(", proto %s (0x%04x)",
 197                    tok2str(ethertype_values,"unknown",prot),
 198                    prot);
 199
 200         printf(", length %u",length);
 201
 202         if (vflag < 1)
 203             printf(": "); /* put in a colon as protocol demarc */
 204         else
 205             printf("\n\t"); /* if verbose go multiline */
 206
 207         switch (prot) {
 208         case ETHERTYPE_IP:
 209                 ip_print(bp, len);
 210                 break;
 211         case ETHERTYPE_IPV6:
 212                 ip6_print(bp, len);
 213                 break;
 214         case ETHERTYPE_MPLS:
 215                 mpls_print(bp, len);
 216                 break;
 217         case ETHERTYPE_IPX:
 218                 ipx_print(bp, len);
 219                 break;
 220         case ETHERTYPE_ATALK:
 221                 atalk_print(bp, len);
 222                 break;
 223         case ETHERTYPE_GRE_ISO:
 224                 isoclns_print(bp, len, len);
 225                 break;
 226         default:
 227                 printf("gre-proto-0x%x", prot);
 228         }
 229         return;
 230
 231 trunc:
 232         printf("[|gre]");
 233 }
 234
 235 void
 236 gre_print_1(const u_char *bp, u_int length)
 237 {
 238         u_int len = length;
 239         u_int16_t flags, prot;
 240
 241         flags = EXTRACT_16BITS(bp);
 242         len -= 2;
 243         bp += 2;
 244
 245         if (vflag)
 246             printf(", Flags [%s]",
 247                    bittok2str(gre_flag_values,"none",flags));
 248
 249         if (len < 2)
 250                 goto trunc;
 251         prot = EXTRACT_16BITS(bp);
 252         len -= 2;
 253         bp += 2;
 254
 255
 256         if (flags & GRE_KP) {
 257                 u_int32_t k;
 258
 259                 if (len < 4)
 260                         goto trunc;
 261                 k = EXTRACT_32BITS(bp);
 262                 printf(", call %d", k & 0xffff);
 263                 len -= 4;
 264                 bp += 4;
 265         }
 266
 267         if (flags & GRE_SP) {
 268                 if (len < 4)
 269                         goto trunc;
 270                 printf(", seq %u", EXTRACT_32BITS(bp));
 271                 bp += 4;
 272                 len -= 4;
 273         }
 274
 275         if (flags & GRE_AP) {
 276                 if (len < 4)
 277                         goto trunc;
 278                 printf(", ack %u", EXTRACT_32BITS(bp));
 279                 bp += 4;
 280                 len -= 4;
 281         }
 282
 283         if ((flags & GRE_SP) == 0) {
 284                 printf(", no-payload");
 285                 return;
 286         }
 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 (vflag < 1)
 296             printf(": "); /* put in a colon as protocol demarc */
 297         else
 298             printf("\n\t"); /* if verbose go multiline */
 299
 300         switch (prot) {
 301         case ETHERTYPE_PPP:
 302                 ppp_print(bp, len);
 303                 break;
 304         default:
 305                 printf("gre-proto-0x%x", prot);
 306                 break;
 307         }
 308         return;
 309
 310 trunc:
 311         printf("[|gre]");
 312 }
 313
 314 void
 315 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 316     const u_char *bp, u_int len)
 317 {
 318         switch (af) {
 319         case GRESRE_IP:
 320                 printf(", (rtaf=ip");
 321                 gre_sre_ip_print(sreoff, srelen, bp, len);
 322                 printf(") ");
 323                 break;
 324         case GRESRE_ASN:
 325                 printf(", (rtaf=asn");
 326                 gre_sre_asn_print(sreoff, srelen, bp, len);
 327                 printf(") ");
 328                 break;
 329         default:
 330                 printf(", (rtaf=0x%x) ", af);
 331         }
 332 }
 333 void
 334 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 335 {
 336         struct in_addr a;
 337         const u_char *up = bp;
 338
 339         if (sreoff & 3) {
 340                 printf(", badoffset=%u", sreoff);
 341                 return;
 342         }
 343         if (srelen & 3) {
 344                 printf(", badlength=%u", srelen);
 345                 return;
 346         }
 347         if (sreoff >= srelen) {
 348                 printf(", badoff/len=%u/%u", sreoff, srelen);
 349                 return;
 350         }
 351
 352         for (;;) {
 353                 if (len < 4 || srelen == 0)
 354                         return;
 355
 356                 memcpy(&a, bp, sizeof(a));
 357                 printf(" %s%s",
 358                     ((bp - up) == sreoff) ? "*" : "",
 359                     inet_ntoa(a));
 360
 361                 bp += 4;
 362                 len -= 4;
 363                 srelen -= 4;
 364         }
 365 }
 366
 367 void
 368 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 369 {
 370         const u_char *up = bp;
 371
 372         if (sreoff & 1) {
 373                 printf(", badoffset=%u", sreoff);
 374                 return;
 375         }
 376         if (srelen & 1) {
 377                 printf(", badlength=%u", srelen);
 378                 return;
 379         }
 380         if (sreoff >= srelen) {
 381                 printf(", badoff/len=%u/%u", sreoff, srelen);
 382                 return;
 383         }
 384
 385         for (;;) {
 386                 if (len < 2 || srelen == 0)
 387                         return;
 388
 389                 printf(" %s%x",
 390                     ((bp - up) == sreoff) ? "*" : "",
 391                     EXTRACT_16BITS(bp));
 392
 393                 bp += 2;
 394                 len -= 2;
 395                 srelen -= 2;
 396         }
 397 }