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   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  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  20  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  21  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  24  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  25  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  26  * POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /* \summary: Generic Routing Encapsulation (GRE) printer */
  30
  31 /*
  32  * netdissect printer for GRE - Generic Routing Encapsulation
  33  * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
  34  */
  35
  36 #ifdef HAVE_CONFIG_H
  37 #include <config.h>
  38 #endif
  39
  40 #include "netdissect-stdinc.h"
  41
  42 #define ND_LONGJMP_FROM_TCHECK
  43 #include "netdissect.h"
  44 #include "addrtostr.h"
  45 #include "extract.h"
  46 #include "ethertype.h"
  47
  48
  49 #define GRE_CP          0x8000          /* checksum present */
  50 #define GRE_RP          0x4000          /* routing present */
  51 #define GRE_KP          0x2000          /* key present */
  52 #define GRE_SP          0x1000          /* sequence# present */
  53 #define GRE_sP          0x0800          /* source routing */
  54 #define GRE_AP          0x0080          /* acknowledgment# present */
  55
  56 static const struct tok gre_flag_values[] = {
  57     { GRE_CP, "checksum present"},
  58     { GRE_RP, "routing present"},
  59     { GRE_KP, "key present"},
  60     { GRE_SP, "sequence# present"},
  61     { GRE_sP, "source routing present"},
  62     { GRE_AP, "ack present"},
  63     { 0, NULL }
  64 };
  65
  66 #define GRE_RECRS_MASK  0x0700          /* recursion count */
  67 #define GRE_VERS_MASK   0x0007          /* protocol version */
  68
  69 /* source route entry types */
  70 #define GRESRE_IP       0x0800          /* IP */
  71 #define GRESRE_ASN      0xfffe          /* ASN */
  72
  73 static void gre_print_0(netdissect_options *, const u_char *, u_int);
  74 static void gre_print_1(netdissect_options *, const u_char *, u_int);
  75 static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  76 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  77 static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  78
  79 void
  80 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
  81 {
  82         u_int vers;
  83
  84         ndo->ndo_protocol = "gre";
  85         nd_print_protocol_caps(ndo);
  86         ND_ICHECK_U(length, <, 2);
  87         vers = GET_BE_U_2(bp) & GRE_VERS_MASK;
  88         ND_PRINT("v%u",vers);
  89
  90         switch(vers) {
  91         case 0:
  92                 gre_print_0(ndo, bp, length);
  93                 break;
  94         case 1:
  95                 gre_print_1(ndo, bp, length);
  96                 break;
  97         default:
  98                 ND_PRINT(" ERROR: unknown-version");
  99                 break;
 100         }
 101         return;
 102
 103 invalid:
 104         nd_print_invalid(ndo);
 105 }
 106
 107 static void
 108 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 109 {
 110         u_int len = length;
 111         uint16_t flags, prot;
 112
 113         ND_ICHECK_U(len, <, 2);
 114         flags = GET_BE_U_2(bp);
 115         if (ndo->ndo_vflag)
 116                 ND_PRINT(", Flags [%s]",
 117                          bittok2str(gre_flag_values,"none",flags));
 118
 119         len -= 2;
 120         bp += 2;
 121
 122         ND_ICHECK_U(len, <, 2);
 123         prot = GET_BE_U_2(bp);
 124         len -= 2;
 125         bp += 2;
 126
 127         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 128                 uint16_t sum;
 129
 130                 ND_ICHECK_U(len, <, 2);
 131                 sum =  GET_BE_U_2(bp);
 132                 if (ndo->ndo_vflag)
 133                         ND_PRINT(", sum 0x%x", sum);
 134                 bp += 2;
 135                 len -= 2;
 136
 137                 ND_ICHECK_U(len, <, 2);
 138                 ND_PRINT(", off 0x%x", GET_BE_U_2(bp));
 139                 bp += 2;
 140                 len -= 2;
 141         }
 142
 143         if (flags & GRE_KP) {
 144                 ND_ICHECK_U(len, <, 4);
 145                 ND_PRINT(", key=0x%x", GET_BE_U_4(bp));
 146                 bp += 4;
 147                 len -= 4;
 148         }
 149
 150         if (flags & GRE_SP) {
 151                 ND_ICHECK_U(len, <, 4);
 152                 ND_PRINT(", seq %u", GET_BE_U_4(bp));
 153                 bp += 4;
 154                 len -= 4;
 155         }
 156
 157         if (flags & GRE_RP) {
 158                 for (;;) {
 159                         uint16_t af;
 160                         uint8_t sreoff;
 161                         uint8_t srelen;
 162
 163                         ND_ICHECK_U(len, <, 4);
 164                         af = GET_BE_U_2(bp);
 165                         sreoff = GET_U_1(bp + 2);
 166                         srelen = GET_U_1(bp + 3);
 167                         bp += 4;
 168                         len -= 4;
 169
 170                         if (af == 0 && srelen == 0)
 171                                 break;
 172
 173                         if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
 174                                 goto invalid;
 175
 176                         ND_ICHECK_U(len, <, srelen);
 177                         bp += srelen;
 178                         len -= srelen;
 179                 }
 180         }
 181
 182         if (ndo->ndo_eflag)
 183                 ND_PRINT(", proto %s (0x%04x)",
 184                          tok2str(ethertype_values,"unknown",prot), prot);
 185
 186         ND_PRINT(", length %u",length);
 187
 188         if (ndo->ndo_vflag < 1)
 189                 ND_PRINT(": "); /* put in a colon as protocol demarc */
 190         else
 191                 ND_PRINT("\n\t"); /* if verbose go multiline */
 192
 193         switch (prot) {
 194         case ETHERTYPE_IP:
 195                 ip_print(ndo, bp, len);
 196                 break;
 197         case ETHERTYPE_IPV6:
 198                 ip6_print(ndo, bp, len);
 199                 break;
 200         case ETHERTYPE_MPLS:
 201                 mpls_print(ndo, bp, len);
 202                 break;
 203         case ETHERTYPE_IPX:
 204                 ipx_print(ndo, bp, len);
 205                 break;
 206         case ETHERTYPE_ATALK:
 207                 atalk_print(ndo, bp, len);
 208                 break;
 209         case ETHERTYPE_GRE_ISO:
 210                 isoclns_print(ndo, bp, len);
 211                 break;
 212         case ETHERTYPE_TEB:
 213                 ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
 214                 break;
 215         default:
 216                 ND_PRINT("gre-proto-0x%x", prot);
 217         }
 218         return;
 219
 220 invalid:
 221         nd_print_invalid(ndo);
 222 }
 223
 224 static void
 225 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 226 {
 227         u_int len = length;
 228         uint16_t flags, prot;
 229
 230         ND_ICHECK_U(len, <, 2);
 231         flags = GET_BE_U_2(bp);
 232         len -= 2;
 233         bp += 2;
 234
 235         if (ndo->ndo_vflag)
 236                 ND_PRINT(", Flags [%s]",
 237                          bittok2str(gre_flag_values,"none",flags));
 238
 239         ND_ICHECK_U(len, <, 2);
 240         prot = GET_BE_U_2(bp);
 241         len -= 2;
 242         bp += 2;
 243
 244
 245         if (flags & GRE_KP) {
 246                 uint32_t k;
 247
 248                 ND_ICHECK_U(len, <, 4);
 249                 k = GET_BE_U_4(bp);
 250                 ND_PRINT(", call %u", k & 0xffff);
 251                 len -= 4;
 252                 bp += 4;
 253         }
 254
 255         if (flags & GRE_SP) {
 256                 ND_ICHECK_U(len, <, 4);
 257                 ND_PRINT(", seq %u", GET_BE_U_4(bp));
 258                 bp += 4;
 259                 len -= 4;
 260         }
 261
 262         if (flags & GRE_AP) {
 263                 ND_ICHECK_U(len, <, 4);
 264                 ND_PRINT(", ack %u", GET_BE_U_4(bp));
 265                 bp += 4;
 266                 len -= 4;
 267         }
 268
 269         if ((flags & GRE_SP) == 0)
 270                 ND_PRINT(", no-payload");
 271
 272         if (ndo->ndo_eflag)
 273                 ND_PRINT(", proto %s (0x%04x)",
 274                          tok2str(ethertype_values,"unknown",prot), prot);
 275
 276         ND_PRINT(", length %u",length);
 277
 278         if ((flags & GRE_SP) == 0)
 279                 return;
 280
 281         if (ndo->ndo_vflag < 1)
 282                 ND_PRINT(": "); /* put in a colon as protocol demarc */
 283         else
 284                 ND_PRINT("\n\t"); /* if verbose go multiline */
 285
 286         switch (prot) {
 287         case ETHERTYPE_PPP:
 288                 ppp_print(ndo, bp, len);
 289                 break;
 290         default:
 291                 ND_PRINT("gre-proto-0x%x", prot);
 292                 break;
 293         }
 294         return;
 295
 296 invalid:
 297         nd_print_invalid(ndo);
 298 }
 299
 300 static int
 301 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 302               uint8_t srelen, const u_char *bp, u_int len)
 303 {
 304         int ret;
 305
 306         switch (af) {
 307         case GRESRE_IP:
 308                 ND_PRINT(", (rtaf=ip");
 309                 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 310                 ND_PRINT(")");
 311                 break;
 312         case GRESRE_ASN:
 313                 ND_PRINT(", (rtaf=asn");
 314                 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 315                 ND_PRINT(")");
 316                 break;
 317         default:
 318                 ND_PRINT(", (rtaf=0x%x)", af);
 319                 ret = 1;
 320         }
 321         return (ret);
 322 }
 323
 324 static int
 325 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 326                  const u_char *bp, u_int len)
 327 {
 328         const u_char *up = bp;
 329         char buf[INET_ADDRSTRLEN];
 330
 331         if (sreoff & 3) {
 332                 ND_PRINT(", badoffset=%u", sreoff);
 333                 goto invalid;
 334         }
 335         if (srelen & 3) {
 336                 ND_PRINT(", badlength=%u", srelen);
 337                 goto invalid;
 338         }
 339         if (sreoff >= srelen) {
 340                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 341                 goto invalid;
 342         }
 343
 344         while (srelen != 0) {
 345                 ND_ICHECK_U(len, <, 4);
 346
 347                 ND_TCHECK_LEN(bp, sizeof(nd_ipv4));
 348                 addrtostr(bp, buf, sizeof(buf));
 349                 ND_PRINT(" %s%s",
 350                          ((bp - up) == sreoff) ? "*" : "", buf);
 351
 352                 bp += 4;
 353                 len -= 4;
 354                 srelen -= 4;
 355         }
 356         return 1;
 357
 358 invalid:
 359         return 0;
 360 }
 361
 362 static int
 363 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 364                   const u_char *bp, u_int len)
 365 {
 366         const u_char *up = bp;
 367
 368         if (sreoff & 1) {
 369                 ND_PRINT(", badoffset=%u", sreoff);
 370                 goto invalid;
 371         }
 372         if (srelen & 1) {
 373                 ND_PRINT(", badlength=%u", srelen);
 374                 goto invalid;
 375         }
 376         if (sreoff >= srelen) {
 377                 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
 378                 goto invalid;
 379         }
 380
 381         while (srelen != 0) {
 382                 ND_ICHECK_U(len, <, 2);
 383
 384                 ND_PRINT(" %s%x",
 385                          ((bp - up) == sreoff) ? "*" : "", GET_BE_U_2(bp));
 386
 387                 bp += 2;
 388                 len -= 2;
 389                 srelen -= 2;
 390         }
 391         return 1;
 392
 393 invalid:
 394         return 0;
 395 }