external/bsd/tcpdump/dist/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 #include <sys/cdefs.h>
  40 #ifndef lint
  41 __RCSID("$NetBSD: print-gre.c,v 1.6 2015/03/31 21:59:35 christos Exp $");
  42 #endif
  43
  44 #define NETDISSECT_REWORKED
  45 #ifdef HAVE_CONFIG_H
  46 #include "config.h"
  47 #endif
  48
  49 #include <tcpdump-stdinc.h>
  50
  51 #include <string.h>
  52
  53 #include "interface.h"
  54 #include "extract.h"
  55 #include "ethertype.h"
  56
  57 static const char tstr[] = "[|gre]";
  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
  67 static const struct tok gre_flag_values[] = {
  68     { GRE_CP, "checksum present"},
  69     { GRE_RP, "routing present"},
  70     { GRE_KP, "key present"},
  71     { GRE_SP, "sequence# present"},
  72     { GRE_sP, "source routing present"},
  73     { GRE_RECRS, "recursion count"},
  74     { GRE_AP, "ack present"},
  75     { 0, NULL }
  76 };
  77
  78 #define GRE_VERS_MASK   0x0007          /* protocol version */
  79
  80 /* source route entry types */
  81 #define GRESRE_IP       0x0800          /* IP */
  82 #define GRESRE_ASN      0xfffe          /* ASN */
  83
  84 static void gre_print_0(netdissect_options *, const u_char *, u_int);
  85 static void gre_print_1(netdissect_options *, const u_char *, u_int);
  86 static void gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
  87 static void gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  88 static void gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
  89
  90 void
  91 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
  92 {
  93         u_int len = length, vers;
  94
  95         if (len < 2) {
  96                 ND_PRINT((ndo, "%s", tstr));
  97                 return;
  98         }
  99         vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
 100         ND_PRINT((ndo, "GREv%u",vers));
 101
 102         switch(vers) {
 103         case 0:
 104             gre_print_0(ndo, bp, len);
 105             break;
 106         case 1:
 107             gre_print_1(ndo, bp, len);
 108             break;
 109         default:
 110             ND_PRINT((ndo, " ERROR: unknown-version"));
 111             break;
 112         }
 113 }
 114
 115 static void
 116 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
 117 {
 118         u_int len = length;
 119         uint16_t flags, prot;
 120
 121         flags = EXTRACT_16BITS(bp);
 122         if (ndo->ndo_vflag)
 123             ND_PRINT((ndo, ", Flags [%s]",
 124                    bittok2str(gre_flag_values,"none",flags)));
 125
 126         len -= 2;
 127         bp += 2;
 128
 129         if (len < 2)
 130                 goto trunc;
 131         prot = EXTRACT_16BITS(bp);
 132         len -= 2;
 133         bp += 2;
 134
 135         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 136                 if (len < 2)
 137                         goto trunc;
 138                 if (ndo->ndo_vflag)
 139                         ND_PRINT((ndo, ", sum 0x%x", EXTRACT_16BITS(bp)));
 140                 bp += 2;
 141                 len -= 2;
 142
 143                 if (len < 2)
 144                         goto trunc;
 145                 ND_PRINT((ndo, ", off 0x%x", EXTRACT_16BITS(bp)));
 146                 bp += 2;
 147                 len -= 2;
 148         }
 149
 150         if (flags & GRE_KP) {
 151                 if (len < 4)
 152                         goto trunc;
 153                 ND_PRINT((ndo, ", key=0x%x", EXTRACT_32BITS(bp)));
 154                 bp += 4;
 155                 len -= 4;
 156         }
 157
 158         if (flags & GRE_SP) {
 159                 if (len < 4)
 160                         goto trunc;
 161                 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
 162                 bp += 4;
 163                 len -= 4;
 164         }
 165
 166         if (flags & GRE_RP) {
 167                 for (;;) {
 168                         uint16_t af;
 169                         uint8_t sreoff;
 170                         uint8_t srelen;
 171
 172                         if (len < 4)
 173                                 goto trunc;
 174                         af = EXTRACT_16BITS(bp);
 175                         sreoff = *(bp + 2);
 176                         srelen = *(bp + 3);
 177                         bp += 4;
 178                         len -= 4;
 179
 180                         if (af == 0 && srelen == 0)
 181                                 break;
 182
 183                         gre_sre_print(ndo, af, sreoff, srelen, bp, len);
 184
 185                         if (len < srelen)
 186                                 goto trunc;
 187                         bp += srelen;
 188                         len -= srelen;
 189                 }
 190         }
 191
 192         if (ndo->ndo_eflag)
 193             ND_PRINT((ndo, ", proto %s (0x%04x)",
 194                    tok2str(ethertype_values,"unknown",prot),
 195                    prot));
 196
 197         ND_PRINT((ndo, ", length %u",length));
 198
 199         if (ndo->ndo_vflag < 1)
 200             ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
 201         else
 202             ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
 203
 204         switch (prot) {
 205         case ETHERTYPE_IP:
 206                 ip_print(ndo, bp, len);
 207                 break;
 208         case ETHERTYPE_IPV6:
 209                 ip6_print(ndo, bp, len);
 210                 break;
 211         case ETHERTYPE_MPLS:
 212                 mpls_print(ndo, bp, len);
 213                 break;
 214         case ETHERTYPE_IPX:
 215                 ipx_print(ndo, bp, len);
 216                 break;
 217         case ETHERTYPE_ATALK:
 218                 atalk_print(ndo, bp, len);
 219                 break;
 220         case ETHERTYPE_GRE_ISO:
 221                 isoclns_print(ndo, bp, len, len);
 222                 break;
 223         case ETHERTYPE_TEB:
 224                 ether_print(ndo, bp, len, len, NULL, NULL);
 225                 break;
 226         default:
 227                 ND_PRINT((ndo, "gre-proto-0x%x", prot));
 228         }
 229         return;
 230
 231 trunc:
 232         ND_PRINT((ndo, "%s", tstr));
 233 }
 234
 235 static void
 236 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
 237 {
 238         u_int len = length;
 239         uint16_t flags, prot;
 240
 241         flags = EXTRACT_16BITS(bp);
 242         len -= 2;
 243         bp += 2;
 244
 245         if (ndo->ndo_vflag)
 246             ND_PRINT((ndo, ", 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                 uint32_t k;
 258
 259                 if (len < 4)
 260                         goto trunc;
 261                 k = EXTRACT_32BITS(bp);
 262                 ND_PRINT((ndo, ", 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                 ND_PRINT((ndo, ", 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                 ND_PRINT((ndo, ", ack %u", EXTRACT_32BITS(bp)));
 279                 bp += 4;
 280                 len -= 4;
 281         }
 282
 283         if ((flags & GRE_SP) == 0)
 284                 ND_PRINT((ndo, ", no-payload"));
 285
 286         if (ndo->ndo_eflag)
 287             ND_PRINT((ndo, ", proto %s (0x%04x)",
 288                    tok2str(ethertype_values,"unknown",prot),
 289                    prot));
 290
 291         ND_PRINT((ndo, ", length %u",length));
 292
 293         if ((flags & GRE_SP) == 0)
 294             return;
 295
 296         if (ndo->ndo_vflag < 1)
 297             ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
 298         else
 299             ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
 300
 301         switch (prot) {
 302         case ETHERTYPE_PPP:
 303                 ppp_print(ndo, bp, len);
 304                 break;
 305         default:
 306                 ND_PRINT((ndo, "gre-proto-0x%x", prot));
 307                 break;
 308         }
 309         return;
 310
 311 trunc:
 312         ND_PRINT((ndo, "%s", tstr));
 313 }
 314
 315 static void
 316 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
 317     uint8_t srelen, const u_char *bp, u_int len)
 318 {
 319         switch (af) {
 320         case GRESRE_IP:
 321                 ND_PRINT((ndo, ", (rtaf=ip"));
 322                 gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
 323                 ND_PRINT((ndo, ") "));
 324                 break;
 325         case GRESRE_ASN:
 326                 ND_PRINT((ndo, ", (rtaf=asn"));
 327                 gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
 328                 ND_PRINT((ndo, ") "));
 329                 break;
 330         default:
 331                 ND_PRINT((ndo, ", (rtaf=0x%x) ", af));
 332         }
 333 }
 334
 335 static void
 336 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 337                  const u_char *bp, u_int len)
 338 {
 339         struct in_addr a;
 340         const u_char *up = bp;
 341
 342         if (sreoff & 3) {
 343                 ND_PRINT((ndo, ", badoffset=%u", sreoff));
 344                 return;
 345         }
 346         if (srelen & 3) {
 347                 ND_PRINT((ndo, ", badlength=%u", srelen));
 348                 return;
 349         }
 350         if (sreoff >= srelen) {
 351                 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
 352                 return;
 353         }
 354
 355         for (;;) {
 356                 if (len < 4 || srelen == 0)
 357                         return;
 358
 359                 memcpy(&a, bp, sizeof(a));
 360                 ND_PRINT((ndo, " %s%s",
 361                     ((bp - up) == sreoff) ? "*" : "",
 362                     inet_ntoa(a)));
 363
 364                 bp += 4;
 365                 len -= 4;
 366                 srelen -= 4;
 367         }
 368 }
 369
 370 static void
 371 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
 372                   const u_char *bp, u_int len)
 373 {
 374         const u_char *up = bp;
 375
 376         if (sreoff & 1) {
 377                 ND_PRINT((ndo, ", badoffset=%u", sreoff));
 378                 return;
 379         }
 380         if (srelen & 1) {
 381                 ND_PRINT((ndo, ", badlength=%u", srelen));
 382                 return;
 383         }
 384         if (sreoff >= srelen) {
 385                 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
 386                 return;
 387         }
 388
 389         for (;;) {
 390                 if (len < 2 || srelen == 0)
 391                         return;
 392
 393                 ND_PRINT((ndo, " %s%x",
 394                     ((bp - up) == sreoff) ? "*" : "",
 395                     EXTRACT_16BITS(bp)));
 396
 397                 bp += 2;
 398                 len -= 2;
 399                 srelen -= 2;
 400         }
 401 }