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 /* \summary: Generic Routing Encapsulation (GRE) printer */
  35
  36 /*
  37  * netdissect printer for GRE - Generic Routing Encapsulation
  38  * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
  39  */
  40
  41 #ifdef HAVE_CONFIG_H
  42 #include "config.h"
  43 #endif
  44
  45 #include <netdissect-stdinc.h>
  46
  47 #include <string.h>
  48
  49 #include "netdissect.h"
  50 #include "addrtostr.h"
  51 #include "extract.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 static void gre_print_0(netdissect_options *, const u_char *, u_int);
  82 static void gre_print_1(netdissect_options *, const u_char *, u_int);
  83 static void gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  84 static void gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  85 static void gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  86
  87 void
  88 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
  89 {
  90         u_int len = length, vers;
  91
  92         if (len < 2) {
  93                 ND_PRINT((ndo, "%s", tstr));
  94                 return;
  95         }
  96         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
  97         ND_PRINT((ndo, "GREv%u",vers));
  98
  99         switch(vers) {
 100         case 0:
 101             gre_print_0(ndo, bp, len);
 102             break;
 103         case 1:
 104             gre_print_1(ndo, bp, len);
 105             break;
 106         default:
 107             ND_PRINT((ndo, " ERROR: unknown-version"));
 108             break;
 109         }
 110 }
 111
 112 static void
 113 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 114 {
 115         u_int len = length;
 116         uint16_t flags, prot;
 117
 118         flags = EXTRACT_16BITS(bp);
 119         if (ndo->ndo_vflag)
 120             ND_PRINT((ndo, ", Flags [%s]",
 121                    bittok2str(gre_flag_values,"none",flags)));
 122
 123         len -= 2;
 124         bp += 2;
 125
 126         if (len < 2)
 127                 goto trunc;
 128         prot = EXTRACT_16BITS(bp);
 129         len -= 2;
 130         bp += 2;
 131
 132         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 133                 if (len < 2)
 134                         goto trunc;
 135                 if (ndo->ndo_vflag)
 136                         ND_PRINT((ndo, ", sum 0x%x", EXTRACT_16BITS(bp)));
 137                 bp += 2;
 138                 len -= 2;
 139
 140                 if (len < 2)
 141                         goto trunc;
 142                 ND_PRINT((ndo, ", off 0x%x", EXTRACT_16BITS(bp)));
 143                 bp += 2;
 144                 len -= 2;
 145         }
 146
 147         if (flags & GRE_KP) {
 148                 if (len < 4)
 149                         goto trunc;
 150                 ND_PRINT((ndo, ", key=0x%x", EXTRACT_32BITS(bp)));
 151                 bp += 4;
 152                 len -= 4;
 153         }
 154
 155         if (flags & GRE_SP) {
 156                 if (len < 4)
 157                         goto trunc;
 158                 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
 159                 bp += 4;
 160                 len -= 4;
 161         }
 162
 163         if (flags & GRE_RP) {
 164                 for (;;) {
 165                         uint16_t af;
 166                         uint8_t sreoff;
 167                         uint8_t srelen;
 168
 169                         if (len < 4)
 170                                 goto trunc;
 171                         af = EXTRACT_16BITS(bp);
 172                         sreoff = *(bp + 2);
 173                         srelen = *(bp + 3);
 174                         bp += 4;
 175                         len -= 4;
 176
 177                         if (af == 0 && srelen == 0)
 178                                 break;
 179
 180                         gre_sre_print(ndo, af, sreoff, srelen, bp, len);
 181
 182                         if (len < srelen)
 183                                 goto trunc;
 184                         bp += srelen;
 185                         len -= srelen;
 186                 }
 187         }
 188
 189         if (ndo->ndo_eflag)
 190             ND_PRINT((ndo, ", proto %s (0x%04x)",
 191                    tok2str(ethertype_values,"unknown",prot),
 192                    prot));
 193
 194         ND_PRINT((ndo, ", length %u",length));
 195
 196         if (ndo->ndo_vflag < 1)
 197             ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
 198         else
 199             ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
 200
 201         switch (prot) {
 202         case ETHERTYPE_IP:
 203                 ip_print(ndo, bp, len);
 204                 break;
 205         case ETHERTYPE_IPV6:
 206                 ip6_print(ndo, bp, len);
 207                 break;
 208         case ETHERTYPE_MPLS:
 209                 mpls_print(ndo, bp, len);
 210                 break;
 211         case ETHERTYPE_IPX:
 212                 ipx_print(ndo, bp, len);
 213                 break;
 214         case ETHERTYPE_ATALK:
 215                 atalk_print(ndo, bp, len);
 216                 break;
 217         case ETHERTYPE_GRE_ISO:
 218                 isoclns_print(ndo, bp, len, len);
 219                 break;
 220         case ETHERTYPE_TEB:
 221                 ether_print(ndo, bp, len, len, NULL, NULL);
 222                 break;
 223         default:
 224                 ND_PRINT((ndo, "gre-proto-0x%x", prot));
 225         }
 226         return;
 227
 228 trunc:
 229         ND_PRINT((ndo, "%s", tstr));
 230 }
 231
 232 static void
 233 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 234 {
 235         u_int len = length;
 236         uint16_t flags, prot;
 237
 238         flags = EXTRACT_16BITS(bp);
 239         len -= 2;
 240         bp += 2;
 241
 242         if (ndo->ndo_vflag)
 243             ND_PRINT((ndo, ", Flags [%s]",
 244                    bittok2str(gre_flag_values,"none",flags)));
 245
 246         if (len < 2)
 247                 goto trunc;
 248         prot = EXTRACT_16BITS(bp);
 249         len -= 2;
 250         bp += 2;
 251
 252
 253         if (flags & GRE_KP) {
 254                 uint32_t k;
 255
 256                 if (len < 4)
 257                         goto trunc;
 258                 k = EXTRACT_32BITS(bp);
 259                 ND_PRINT((ndo, ", call %d", k & 0xffff));
 260                 len -= 4;
 261                 bp += 4;
 262         }
 263
 264         if (flags & GRE_SP) {
 265                 if (len < 4)
 266                         goto trunc;
 267                 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
 268                 bp += 4;
 269                 len -= 4;
 270         }
 271
 272         if (flags & GRE_AP) {
 273                 if (len < 4)
 274                         goto trunc;
 275                 ND_PRINT((ndo, ", ack %u", EXTRACT_32BITS(bp)));
 276                 bp += 4;
 277                 len -= 4;
 278         }
 279
 280         if ((flags & GRE_SP) == 0)
 281                 ND_PRINT((ndo, ", no-payload"));
 282
 283         if (ndo->ndo_eflag)
 284             ND_PRINT((ndo, ", proto %s (0x%04x)",
 285                    tok2str(ethertype_values,"unknown",prot),
 286                    prot));
 287
 288         ND_PRINT((ndo, ", length %u",length));
 289
 290         if ((flags & GRE_SP) == 0)
 291             return;
 292
 293         if (ndo->ndo_vflag < 1)
 294             ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
 295         else
 296             ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
 297
 298         switch (prot) {
 299         case ETHERTYPE_PPP:
 300                 ppp_print(ndo, bp, len);
 301                 break;
 302         default:
 303                 ND_PRINT((ndo, "gre-proto-0x%x", prot));
 304                 break;
 305         }
 306         return;
 307
 308 trunc:
 309         ND_PRINT((ndo, "%s", tstr));
 310 }
 311
 312 static void
 313 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 314     uint8_t srelen, const u_char *bp, u_int len)
 315 {
 316         switch (af) {
 317         case GRESRE_IP:
 318                 ND_PRINT((ndo, ", (rtaf=ip"));
 319                 gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 320                 ND_PRINT((ndo, ")"));
 321                 break;
 322         case GRESRE_ASN:
 323                 ND_PRINT((ndo, ", (rtaf=asn"));
 324                 gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 325                 ND_PRINT((ndo, ")"));
 326                 break;
 327         default:
 328                 ND_PRINT((ndo, ", (rtaf=0x%x)", af));
 329         }
 330 }
 331
 332 static void
 333 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 334                  const u_char *bp, u_int len)
 335 {
 336         const u_char *up = bp;
 337         char buf[INET_ADDRSTRLEN];
 338
 339         if (sreoff & 3) {
 340                 ND_PRINT((ndo, ", badoffset=%u", sreoff));
 341                 return;
 342         }
 343         if (srelen & 3) {
 344                 ND_PRINT((ndo, ", badlength=%u", srelen));
 345                 return;
 346         }
 347         if (sreoff >= srelen) {
 348                 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
 349                 return;
 350         }
 351
 352         for (;;) {
 353                 if (len < 4 || srelen == 0)
 354                         return;
 355
 356                 addrtostr(bp, buf, sizeof(buf));
 357                 ND_PRINT((ndo, " %s%s",
 358                     ((bp - up) == sreoff) ? "*" : "", buf));
 359
 360                 bp += 4;
 361                 len -= 4;
 362                 srelen -= 4;
 363         }
 364 }
 365
 366 static void
 367 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 368                   const u_char *bp, u_int len)
 369 {
 370         const u_char *up = bp;
 371
 372         if (sreoff & 1) {
 373                 ND_PRINT((ndo, ", badoffset=%u", sreoff));
 374                 return;
 375         }
 376         if (srelen & 1) {
 377                 ND_PRINT((ndo, ", badlength=%u", srelen));
 378                 return;
 379         }
 380         if (sreoff >= srelen) {
 381                 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
 382                 return;
 383         }
 384
 385         for (;;) {
 386                 if (len < 2 || srelen == 0)
 387                         return;
 388
 389                 ND_PRINT((ndo, " %s%x",
 390                     ((bp - up) == sreoff) ? "*" : "",
 391                     EXTRACT_16BITS(bp)));
 392
 393                 bp += 2;
 394                 len -= 2;
 395                 srelen -= 2;
 396         }
 397 }