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[] =
  41     "@(#) $Header: /tcpdump/master/tcpdump/print-gre.c,v 1.20 2002-10-30 05:29:16 itojun 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
  59 #define GRE_CP          0x8000          /* checksum present */
  60 #define GRE_RP          0x4000          /* routing present */
  61 #define GRE_KP          0x2000          /* key present */
  62 #define GRE_SP          0x1000          /* sequence# present */
  63 #define GRE_sP          0x0800          /* source routing */
  64 #define GRE_RECRS       0x0700          /* recursion count */
  65 #define GRE_AP          0x0080          /* acknowledgment# present */
  66 #define GRE_VERS        0x0007          /* protocol version */
  67
  68 #define GREPROTO_IP     0x0800          /* IP */
  69 #define GREPROTO_PPP    0x880b          /* PPTP */
  70 #define GREPROTO_ISO    0xfefe          /* OSI */
  71
  72 /* source route entry types */
  73 #define GRESRE_IP       0x0800          /* IP */
  74 #define GRESRE_ASN      0xfffe          /* ASN */
  75
  76 void gre_print_0(const u_char *, u_int);
  77 void gre_print_1(const u_char *, u_int);
  78 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  79 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  80 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  81
  82 void
  83 gre_print(const u_char *bp, u_int length)
  84 {
  85         u_int len = length, vers;
  86
  87         if (len < 2) {
  88                 printf("[|gre]");
  89                 return;
  90         }
  91         vers = EXTRACT_16BITS(bp) & 7;
  92
  93         if (vers == 0)
  94                 gre_print_0(bp, len);
  95         else if (vers == 1)
  96                 gre_print_1(bp, len);
  97         else
  98                 printf("gre-unknown-version=%u", vers);
  99         return;
 100
 101 }
 102
 103 void
 104 gre_print_0(const u_char *bp, u_int length)
 105 {
 106         u_int len = length;
 107         u_int16_t flags, prot;
 108
 109         flags = EXTRACT_16BITS(bp);
 110         if (vflag) {
 111                 printf("[%s%s%s%s%s] ",
 112                     (flags & GRE_CP) ? "C" : "",
 113                     (flags & GRE_RP) ? "R" : "",
 114                     (flags & GRE_KP) ? "K" : "",
 115                     (flags & GRE_SP) ? "S" : "",
 116                     (flags & GRE_sP) ? "s" : "");
 117         }
 118
 119         len -= 2;
 120         bp += 2;
 121
 122         if (len < 2)
 123                 goto trunc;
 124         prot = EXTRACT_16BITS(bp);
 125         len -= 2;
 126         bp += 2;
 127
 128         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 129                 if (len < 2)
 130                         goto trunc;
 131                 if (vflag)
 132                         printf("sum 0x%x ", EXTRACT_16BITS(bp));
 133                 bp += 2;
 134                 len -= 2;
 135
 136                 if (len < 2)
 137                         goto trunc;
 138                 printf("off 0x%x ", EXTRACT_16BITS(bp));
 139                 bp += 2;
 140                 len -= 2;
 141         }
 142
 143         if (flags & GRE_KP) {
 144                 if (len < 4)
 145                         goto trunc;
 146                 printf("key=0x%x ", EXTRACT_32BITS(bp));
 147                 bp += 4;
 148                 len -= 4;
 149         }
 150
 151         if (flags & GRE_SP) {
 152                 if (len < 4)
 153                         goto trunc;
 154                 printf("seq %u ", EXTRACT_32BITS(bp));
 155                 bp += 4;
 156                 len -= 4;
 157         }
 158
 159         if (flags & GRE_RP) {
 160                 for (;;) {
 161                         u_int16_t af;
 162                         u_int8_t sreoff;
 163                         u_int8_t srelen;
 164
 165                         if (len < 4)
 166                                 goto trunc;
 167                         af = EXTRACT_16BITS(bp);
 168                         sreoff = *(bp + 2);
 169                         srelen = *(bp + 3);
 170                         bp += 4;
 171                         len -= 4;
 172
 173                         if (af == 0 && srelen == 0)
 174                                 break;
 175
 176                         gre_sre_print(af, sreoff, srelen, bp, len);
 177
 178                         if (len < srelen)
 179                                 goto trunc;
 180                         bp += srelen;
 181                         len -= srelen;
 182                 }
 183         }
 184
 185         switch (prot) {
 186         case GREPROTO_IP:
 187                 ip_print(bp, len);
 188                 break;
 189         case GREPROTO_ISO:
 190                 isoclns_print(bp, len, len, NULL, NULL);
 191                 break;
 192         default:
 193                 printf("gre-proto-0x%x", prot);
 194         }
 195         return;
 196
 197 trunc:
 198         printf("[|gre]");
 199 }
 200
 201 void
 202 gre_print_1(const u_char *bp, u_int length)
 203 {
 204         u_int len = length;
 205         u_int16_t flags, prot;
 206
 207         flags = EXTRACT_16BITS(bp);
 208         len -= 2;
 209         bp += 2;
 210
 211         if (vflag) {
 212                 printf("[%s%s%s%s%s%s] ",
 213                     (flags & GRE_CP) ? "C" : "",
 214                     (flags & GRE_RP) ? "R" : "",
 215                     (flags & GRE_KP) ? "K" : "",
 216                     (flags & GRE_SP) ? "S" : "",
 217                     (flags & GRE_sP) ? "s" : "",
 218                     (flags & GRE_AP) ? "A" : "");
 219         }
 220
 221         if (len < 2)
 222                 goto trunc;
 223         prot = EXTRACT_16BITS(bp);
 224         len -= 2;
 225         bp += 2;
 226
 227         if (flags & GRE_CP) {
 228                 printf("cpset!");
 229                 return;
 230         }
 231         if (flags & GRE_RP) {
 232                 printf("rpset!");
 233                 return;
 234         }
 235         if ((flags & GRE_KP) == 0) {
 236                 printf("kpunset!");
 237                 return;
 238         }
 239         if (flags & GRE_sP) {
 240                 printf("spset!");
 241                 return;
 242         }
 243
 244         if (flags & GRE_KP) {
 245                 u_int32_t k;
 246
 247                 if (len < 4)
 248                         goto trunc;
 249                 k = EXTRACT_32BITS(bp);
 250                 printf("call %d ", k & 0xffff);
 251                 len -= 4;
 252                 bp += 4;
 253         }
 254
 255         if (flags & GRE_SP) {
 256                 if (len < 4)
 257                         goto trunc;
 258                 printf("seq %u ", EXTRACT_32BITS(bp));
 259                 bp += 4;
 260                 len -= 4;
 261         }
 262
 263         if (flags & GRE_AP) {
 264                 if (len < 4)
 265                         goto trunc;
 266                 printf("ack %u ", EXTRACT_32BITS(bp));
 267                 bp += 4;
 268                 len -= 4;
 269         }
 270
 271         if ((flags & GRE_SP) == 0) {
 272                 printf("no-payload");
 273                 return;
 274         }
 275
 276         switch (prot) {
 277         case GREPROTO_PPP:
 278                 printf("gre-ppp-payload");
 279                 break;
 280         default:
 281                 printf("gre-proto-0x%x", prot);
 282                 break;
 283         }
 284         return;
 285
 286 trunc:
 287         printf("[|gre]");
 288 }
 289
 290 void
 291 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 292     const u_char *bp, u_int len)
 293 {
 294         switch (af) {
 295         case GRESRE_IP:
 296                 printf("(rtaf=ip");
 297                 gre_sre_ip_print(sreoff, srelen, bp, len);
 298                 printf(") ");
 299                 break;
 300         case GRESRE_ASN:
 301                 printf("(rtaf=asn");
 302                 gre_sre_asn_print(sreoff, srelen, bp, len);
 303                 printf(") ");
 304                 break;
 305         default:
 306                 printf("(rtaf=0x%x) ", af);
 307         }
 308 }
 309 void
 310 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 311 {
 312         struct in_addr a;
 313         const u_char *up = bp;
 314
 315         if (sreoff & 3) {
 316                 printf(" badoffset=%u", sreoff);
 317                 return;
 318         }
 319         if (srelen & 3) {
 320                 printf(" badlength=%u", srelen);
 321                 return;
 322         }
 323         if (sreoff >= srelen) {
 324                 printf(" badoff/len=%u/%u", sreoff, srelen);
 325                 return;
 326         }
 327
 328         for (;;) {
 329                 if (len < 4 || srelen == 0)
 330                         return;
 331
 332                 memcpy(&a, bp, sizeof(a));
 333                 printf(" %s%s",
 334                     ((bp - up) == sreoff) ? "*" : "",
 335                     inet_ntoa(a));
 336
 337                 bp += 4;
 338                 len -= 4;
 339                 srelen -= 4;
 340         }
 341 }
 342
 343 void
 344 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 345 {
 346         const u_char *up = bp;
 347
 348         if (sreoff & 1) {
 349                 printf(" badoffset=%u", sreoff);
 350                 return;
 351         }
 352         if (srelen & 1) {
 353                 printf(" badlength=%u", srelen);
 354                 return;
 355         }
 356         if (sreoff >= srelen) {
 357                 printf(" badoff/len=%u/%u", sreoff, srelen);
 358                 return;
 359         }
 360
 361         for (;;) {
 362                 if (len < 2 || srelen == 0)
 363                         return;
 364
 365                 printf(" %s%x",
 366                     ((bp - up) == sreoff) ? "*" : "",
 367                     EXTRACT_16BITS(bp));
 368
 369                 bp += 2;
 370                 len -= 2;
 371                 srelen -= 2;
 372         }
 373 }