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 int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  84 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  85 static int 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         ND_TCHECK_2(bp);
  93         if (len < 2)
  94                 goto trunc;
  95         vers = EXTRACT_BE_U_2(bp) & GRE_VERS_MASK;
  96         ND_PRINT("GREv%u",vers);
  97
  98         switch(vers) {
  99         case 0:
 100             gre_print_0(ndo, bp, len);
 101             break;
 102         case 1:
 103             gre_print_1(ndo, bp, len);
 104             break;
 105         default:
 106             ND_PRINT(" ERROR: unknown-version");
 107             break;
 108         }
 109         return;
 110
 111 trunc:
 112         ND_PRINT("%s", tstr);
 113         return;
 114 }
 115
 116 static void
 117 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 118 {
 119         u_int len = length;
 120         uint16_t flags, prot;
 121
 122         /* 16 bits ND_TCHECKed in gre_print() */
 123         flags = EXTRACT_BE_U_2(bp);
 124         if (ndo->ndo_vflag)
 125             ND_PRINT(", Flags [%s]",
 126                    bittok2str(gre_flag_values,"none",flags));
 127
 128         len -= 2;
 129         bp += 2;
 130
 131         ND_TCHECK_2(bp);
 132         if (len < 2)
 133                 goto trunc;
 134         prot = EXTRACT_BE_U_2(bp);
 135         len -= 2;
 136         bp += 2;
 137
 138         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 139                 ND_TCHECK_2(bp);
 140                 if (len < 2)
 141                         goto trunc;
 142                 if (ndo->ndo_vflag)
 143                         ND_PRINT(", sum 0x%x", EXTRACT_BE_U_2(bp));
 144                 bp += 2;
 145                 len -= 2;
 146
 147                 ND_TCHECK_2(bp);
 148                 if (len < 2)
 149                         goto trunc;
 150                 ND_PRINT(", off 0x%x", EXTRACT_BE_U_2(bp));
 151                 bp += 2;
 152                 len -= 2;
 153         }
 154
 155         if (flags & GRE_KP) {
 156                 ND_TCHECK_4(bp);
 157                 if (len < 4)
 158                         goto trunc;
 159                 ND_PRINT(", key=0x%x", EXTRACT_BE_U_4(bp));
 160                 bp += 4;
 161                 len -= 4;
 162         }
 163
 164         if (flags & GRE_SP) {
 165                 ND_TCHECK_4(bp);
 166                 if (len < 4)
 167                         goto trunc;
 168                 ND_PRINT(", seq %u", EXTRACT_BE_U_4(bp));
 169                 bp += 4;
 170                 len -= 4;
 171         }
 172
 173         if (flags & GRE_RP) {
 174                 for (;;) {
 175                         uint16_t af;
 176                         uint8_t sreoff;
 177                         uint8_t srelen;
 178
 179                         ND_TCHECK_4(bp);
 180                         if (len < 4)
 181                                 goto trunc;
 182                         af = EXTRACT_BE_U_2(bp);
 183                         sreoff = EXTRACT_U_1(bp + 2);
 184                         srelen = EXTRACT_U_1(bp + 3);
 185                         bp += 4;
 186                         len -= 4;
 187
 188                         if (af == 0 && srelen == 0)
 189                                 break;
 190
 191                         if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
 192                                 goto trunc;
 193
 194                         if (len < srelen)
 195                                 goto trunc;
 196                         bp += srelen;
 197                         len -= srelen;
 198                 }
 199         }
 200
 201         if (ndo->ndo_eflag)
 202             ND_PRINT(", proto %s (0x%04x)",
 203                    tok2str(ethertype_values,"unknown",prot),
 204                    prot);
 205
 206         ND_PRINT(", length %u",length);
 207
 208         if (ndo->ndo_vflag < 1)
 209             ND_PRINT(": "); /* put in a colon as protocol demarc */
 210         else
 211             ND_PRINT("\n\t"); /* if verbose go multiline */
 212
 213         switch (prot) {
 214         case ETHERTYPE_IP:
 215                 ip_print(ndo, bp, len);
 216                 break;
 217         case ETHERTYPE_IPV6:
 218                 ip6_print(ndo, bp, len);
 219                 break;
 220         case ETHERTYPE_MPLS:
 221                 mpls_print(ndo, bp, len);
 222                 break;
 223         case ETHERTYPE_IPX:
 224                 ipx_print(ndo, bp, len);
 225                 break;
 226         case ETHERTYPE_ATALK:
 227                 atalk_print(ndo, bp, len);
 228                 break;
 229         case ETHERTYPE_GRE_ISO:
 230                 isoclns_print(ndo, bp, len);
 231                 break;
 232         case ETHERTYPE_TEB:
 233                 ether_print(ndo, bp, len, ndo->ndo_snapend - bp, NULL, NULL);
 234                 break;
 235         default:
 236                 ND_PRINT("gre-proto-0x%x", prot);
 237         }
 238         return;
 239
 240 trunc:
 241         ND_PRINT("%s", tstr);
 242 }
 243
 244 static void
 245 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 246 {
 247         u_int len = length;
 248         uint16_t flags, prot;
 249
 250         /* 16 bits ND_TCHECKed in gre_print() */
 251         flags = EXTRACT_BE_U_2(bp);
 252         len -= 2;
 253         bp += 2;
 254
 255         if (ndo->ndo_vflag)
 256             ND_PRINT(", Flags [%s]",
 257                    bittok2str(gre_flag_values,"none",flags));
 258
 259         ND_TCHECK_2(bp);
 260         if (len < 2)
 261                 goto trunc;
 262         prot = EXTRACT_BE_U_2(bp);
 263         len -= 2;
 264         bp += 2;
 265
 266
 267         if (flags & GRE_KP) {
 268                 uint32_t k;
 269
 270                 ND_TCHECK_4(bp);
 271                 if (len < 4)
 272                         goto trunc;
 273                 k = EXTRACT_BE_U_4(bp);
 274                 ND_PRINT(", call %u", k & 0xffff);
 275                 len -= 4;
 276                 bp += 4;
 277         }
 278
 279         if (flags & GRE_SP) {
 280                 ND_TCHECK_4(bp);
 281                 if (len < 4)
 282                         goto trunc;
 283                 ND_PRINT(", seq %u", EXTRACT_BE_U_4(bp));
 284                 bp += 4;
 285                 len -= 4;
 286         }
 287
 288         if (flags & GRE_AP) {
 289                 ND_TCHECK_4(bp);
 290                 if (len < 4)
 291                         goto trunc;
 292                 ND_PRINT(", ack %u", EXTRACT_BE_U_4(bp));
 293                 bp += 4;
 294                 len -= 4;
 295         }
 296
 297         if ((flags & GRE_SP) == 0)
 298                 ND_PRINT(", no-payload");
 299
 300         if (ndo->ndo_eflag)
 301             ND_PRINT(", proto %s (0x%04x)",
 302                    tok2str(ethertype_values,"unknown",prot),
 303                    prot);
 304
 305         ND_PRINT(", length %u",length);
 306
 307         if ((flags & GRE_SP) == 0)
 308             return;
 309
 310         if (ndo->ndo_vflag < 1)
 311             ND_PRINT(": "); /* put in a colon as protocol demarc */
 312         else
 313             ND_PRINT("\n\t"); /* if verbose go multiline */
 314
 315         switch (prot) {
 316         case ETHERTYPE_PPP:
 317                 ppp_print(ndo, bp, len);
 318                 break;
 319         default:
 320                 ND_PRINT("gre-proto-0x%x", prot);
 321                 break;
 322         }
 323         return;
 324
 325 trunc:
 326         ND_PRINT("%s", tstr);
 327 }
 328
 329 static int
 330 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 331     uint8_t srelen, const u_char *bp, u_int len)
 332 {
 333         int ret;
 334
 335         switch (af) {
 336         case GRESRE_IP:
 337                 ND_PRINT(", (rtaf=ip");
 338                 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 339                 ND_PRINT(")");
 340                 break;
 341         case GRESRE_ASN:
 342                 ND_PRINT(", (rtaf=asn");
 343                 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 344                 ND_PRINT(")");
 345                 break;
 346         default:
 347                 ND_PRINT(", (rtaf=0x%x)", af);
 348                 ret = 1;
 349         }
 350         return (ret);
 351 }
 352
 353 static int
 354 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 355                  const u_char *bp, u_int len)
 356 {
 357         const u_char *up = bp;
 358         char buf[INET_ADDRSTRLEN];
 359
 360         if (sreoff & 3) {
 361                 ND_PRINT(", badoffset=%u", sreoff);
 362                 return (1);
 363         }
 364         if (srelen & 3) {
 365                 ND_PRINT(", badlength=%u", srelen);
 366                 return (1);
 367         }
 368         if (sreoff >= srelen) {
 369                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 370                 return (1);
 371         }
 372
 373         while (srelen != 0) {
 374                 if (!ND_TTEST_4(bp))
 375                         return (0);
 376                 if (len < 4)
 377                         return (0);
 378
 379                 addrtostr(bp, buf, sizeof(buf));
 380                 ND_PRINT(" %s%s",
 381                     ((bp - up) == sreoff) ? "*" : "", buf);
 382
 383                 bp += 4;
 384                 len -= 4;
 385                 srelen -= 4;
 386         }
 387         return (1);
 388 }
 389
 390 static int
 391 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 392                   const u_char *bp, u_int len)
 393 {
 394         const u_char *up = bp;
 395
 396         if (sreoff & 1) {
 397                 ND_PRINT(", badoffset=%u", sreoff);
 398                 return (1);
 399         }
 400         if (srelen & 1) {
 401                 ND_PRINT(", badlength=%u", srelen);
 402                 return (1);
 403         }
 404         if (sreoff >= srelen) {
 405                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 406                 return (1);
 407         }
 408
 409         while (srelen != 0) {
 410                 if (!ND_TTEST_2(bp))
 411                         return (0);
 412                 if (len < 2)
 413                         return (0);
 414
 415                 ND_PRINT(" %s%x",
 416                     ((bp - up) == sreoff) ? "*" : "",
 417                     EXTRACT_BE_U_2(bp));
 418
 419                 bp += 2;
 420                 len -= 2;
 421                 srelen -= 2;
 422         }
 423         return (1);
 424 }