The Tcpdump Group git mirrors - tcpdump/blob - print-gre.c

   1 /*      $OpenBSD: print-gre.c,v 1.5 2002/09/18 20:40:06 jason 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 1.17 2002-09-20 22:42:21 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
  71 /* source route entry types */
  72 #define GRESRE_IP       0x0800          /* IP */
  73 #define GRESRE_ASN      0xfffe          /* ASN */
  74
  75 void gre_print_0(const u_char *, u_int);
  76 void gre_print_1(const u_char *, u_int);
  77 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
  78 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
  79 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
  80
  81 void
  82 gre_print(const u_char *bp, u_int length)
  83 {
  84         u_int len = length, vers;
  85
  86         if (len < 2) {
  87                 printf("[|gre]");
  88                 return;
  89         }
  90         vers = EXTRACT_16BITS(bp) & 7;
  91
  92         if (vers == 0)
  93                 gre_print_0(bp, len);
  94         else if (vers == 1)
  95                 gre_print_1(bp, len);
  96         else
  97                 printf("gre-unknown-version=%u", vers);
  98         return;
  99
 100 }
 101
 102 void
 103 gre_print_0(const u_char *bp, u_int length)
 104 {
 105         u_int len = length;
 106         u_int16_t flags, prot;
 107
 108         flags = EXTRACT_16BITS(bp);
 109         if (vflag) {
 110                 printf("[%s%s%s%s%s] ",
 111                     (flags & GRE_CP) ? "C" : "",
 112                     (flags & GRE_RP) ? "R" : "",
 113                     (flags & GRE_KP) ? "K" : "",
 114                     (flags & GRE_SP) ? "S" : "",
 115                     (flags & GRE_sP) ? "s" : "");
 116         }
 117
 118         len -= 2;
 119         bp += 2;
 120
 121         if (len < 2)
 122                 goto trunc;
 123         prot = EXTRACT_16BITS(bp);
 124         len -= 2;
 125         bp += 2;
 126
 127         if ((flags & GRE_CP) | (flags & GRE_RP)) {
 128                 if (len < 2)
 129                         goto trunc;
 130                 if (vflag)
 131                         printf("sum 0x%x ", EXTRACT_16BITS(bp));
 132                 bp += 2;
 133                 len -= 2;
 134
 135                 if (len < 2)
 136                         goto trunc;
 137                 printf("off 0x%x ", EXTRACT_16BITS(bp));
 138                 bp += 2;
 139                 len -= 2;
 140         }
 141
 142         if (flags & GRE_KP) {
 143                 if (len < 4)
 144                         goto trunc;
 145                 printf("key=0x%x ", EXTRACT_32BITS(bp));
 146                 bp += 4;
 147                 len -= 4;
 148         }
 149
 150         if (flags & GRE_SP) {
 151                 if (len < 4)
 152                         goto trunc;
 153                 printf("seq=0x%x ", EXTRACT_32BITS(bp));
 154                 bp += 4;
 155                 len -= 4;
 156         }
 157
 158         if (flags & GRE_RP) {
 159                 for (;;) {
 160                         u_int16_t af;
 161                         u_int8_t sreoff;
 162                         u_int8_t srelen;
 163
 164                         if (len < 4)
 165                                 goto trunc;
 166                         af = EXTRACT_16BITS(bp);
 167                         sreoff = *(bp + 2);
 168                         srelen = *(bp + 3);
 169                         bp += 4;
 170                         len -= 4;
 171
 172                         if (af == 0 && srelen == 0)
 173                                 break;
 174
 175                         gre_sre_print(af, sreoff, srelen, bp, len);
 176
 177                         if (len < srelen)
 178                                 goto trunc;
 179                         bp += srelen;
 180                         len -= srelen;
 181                 }
 182         }
 183
 184         switch (prot) {
 185         case GREPROTO_IP:
 186                 ip_print(bp, len);
 187                 break;
 188         default:
 189                 printf("gre-proto-0x%x", prot);
 190         }
 191         return;
 192
 193 trunc:
 194         printf("[|gre]");
 195 }
 196
 197 void
 198 gre_print_1(const u_char *bp, u_int length)
 199 {
 200         u_int len = length;
 201         u_int16_t flags, prot;
 202
 203         flags = EXTRACT_16BITS(bp);
 204         len -= 2;
 205         bp += 2;
 206
 207         if (vflag) {
 208                 printf("[%s%s%s%s%s%s] ",
 209                     (flags & GRE_CP) ? "C" : "",
 210                     (flags & GRE_RP) ? "R" : "",
 211                     (flags & GRE_KP) ? "K" : "",
 212                     (flags & GRE_SP) ? "S" : "",
 213                     (flags & GRE_sP) ? "s" : "",
 214                     (flags & GRE_AP) ? "A" : "");
 215         }
 216
 217         if (len < 2)
 218                 goto trunc;
 219         prot = EXTRACT_16BITS(bp);
 220         len -= 2;
 221         bp += 2;
 222
 223         if (flags & GRE_CP) {
 224                 printf("cpset! ");
 225                 return;
 226         }
 227         if (flags & GRE_RP) {
 228                 printf("rpset! ");
 229                 return;
 230         }
 231         if ((flags & GRE_KP) != 0) {
 232                 printf("kpunset! ");
 233                 return;
 234         }
 235         if (flags & GRE_sP) {
 236                 printf("spset! ");
 237                 return;
 238         }
 239
 240         if (flags & GRE_KP) {
 241                 u_int32_t k;
 242
 243                 if (len < 4)
 244                         goto trunc;
 245                 k = EXTRACT_32BITS(bp);
 246                 printf("key=0x%x call=0x%x ", (k >> 16) & 0xffff, k & 0xffff);
 247                 len -= 4;
 248                 bp += 4;
 249         }
 250
 251         if (flags & GRE_SP) {
 252                 if (len < 4)
 253                         goto trunc;
 254                 printf("seq=0x%x ", EXTRACT_32BITS(bp));
 255                 bp += 4;
 256                 len -= 4;
 257         }
 258
 259         if (flags & GRE_AP) {
 260                 if (len < 4)
 261                         goto trunc;
 262                 printf("ack=0x%x ", EXTRACT_32BITS(bp));
 263                 bp += 4;
 264                 len -= 4;
 265         }
 266
 267         if ((flags & GRE_SP) == 0) {
 268                 printf("no-payload ");
 269                 return;
 270         }
 271
 272         switch (prot) {
 273         case GREPROTO_PPP:
 274                 printf("gre-ppp-payload ");
 275                 break;
 276         default:
 277                 printf("gre-proto-0x%x ", prot);
 278                 break;
 279         }
 280         return;
 281
 282 trunc:
 283         printf("[|gre]");
 284 }
 285
 286 void
 287 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
 288     const u_char *bp, u_int len)
 289 {
 290         switch (af) {
 291         case GRESRE_IP:
 292                 printf("(rtaf=ip");
 293                 gre_sre_ip_print(sreoff, srelen, bp, len);
 294                 printf(") ");
 295                 break;
 296         case GRESRE_ASN:
 297                 printf("(rtaf=asn");
 298                 gre_sre_asn_print(sreoff, srelen, bp, len);
 299                 printf(") ");
 300                 break;
 301         default:
 302                 printf("(rtaf=0x%x) ", af);
 303         }
 304 }
 305 void
 306 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 307 {
 308         struct in_addr a;
 309         const u_char *up = bp;
 310
 311         if (sreoff & 3) {
 312                 printf(" badoffset=%u", sreoff);
 313                 return;
 314         }
 315         if (srelen & 3) {
 316                 printf(" badlength=%u", srelen);
 317                 return;
 318         }
 319         if (sreoff >= srelen) {
 320                 printf(" badoff/len=%u/%u", sreoff, srelen);
 321                 return;
 322         }
 323
 324         for (;;) {
 325                 if (len < 4 || srelen == 0)
 326                         return;
 327
 328                 memcpy(&a, bp, sizeof(a));
 329                 printf(" %s%s",
 330                     ((bp - up) == sreoff) ? "*" : "",
 331                     inet_ntoa(a));
 332
 333                 bp += 4;
 334                 len -= 4;
 335                 srelen -= 4;
 336         }
 337 }
 338
 339 void
 340 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
 341 {
 342         const u_char *up = bp;
 343
 344         if (sreoff & 1) {
 345                 printf(" badoffset=%u", sreoff);
 346                 return;
 347         }
 348         if (srelen & 1) {
 349                 printf(" badlength=%u", srelen);
 350                 return;
 351         }
 352         if (sreoff >= srelen) {
 353                 printf(" badoff/len=%u/%u", sreoff, srelen);
 354                 return;
 355         }
 356
 357         for (;;) {
 358                 if (len < 2 || srelen == 0)
 359                         return;
 360
 361                 printf(" %s%x",
 362                     ((bp - up) == sreoff) ? "*" : "",
 363                     EXTRACT_16BITS(bp));
 364
 365                 bp += 2;
 366                 len -= 2;
 367                 srelen -= 2;
 368         }
 369 }