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 #ifndef lint 40 static const char rcsid[] _U_ = 41 "@(#) $Header: /tcpdump/master/tcpdump/print-gre.c,v 1.28 2005-04-06 21:32:39 mcr 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 #include "ethertype.h" 59 60 #define GRE_CP 0x8000 /* checksum present */ 61 #define GRE_RP 0x4000 /* routing present */ 62 #define GRE_KP 0x2000 /* key present */ 63 #define GRE_SP 0x1000 /* sequence# present */ 64 #define GRE_sP 0x0800 /* source routing */ 65 #define GRE_RECRS 0x0700 /* recursion count */ 66 #define GRE_AP 0x0080 /* acknowledgment# present */ 67 68 struct tok gre_flag_values[] = { 69 { GRE_CP, "checksum present"}, 70 { GRE_RP, "routing present"}, 71 { GRE_KP, "key present"}, 72 { GRE_SP, "sequence# present"}, 73 { GRE_sP, "source routing present"}, 74 { GRE_RECRS, "recursion count"}, 75 { GRE_AP, "ack present"}, 76 { 0, NULL } 77 }; 78 79 #define GRE_VERS_MASK 0x0007 /* protocol version */ 80 81 /* source route entry types */ 82 #define GRESRE_IP 0x0800 /* IP */ 83 #define GRESRE_ASN 0xfffe /* ASN */ 84 85 void gre_print_0(const u_char *, u_int); 86 void gre_print_1(const u_char *, u_int); 87 void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int); 88 void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int); 89 void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int); 90 91 void 92 gre_print(const u_char *bp, u_int length) 93 { 94 u_int len = length, vers; 95 96 if (len < 2) { 97 printf("[|gre]"); 98 return; 99 } 100 vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK; 101 printf("GREv%u",vers); 102 103 switch(vers) { 104 case 0: 105 gre_print_0(bp, len); 106 break; 107 case 1: 108 gre_print_1(bp, len); 109 break; 110 default: 111 printf(" ERROR: unknown-version"); 112 break; 113 } 114 return; 115 116 } 117 118 void 119 gre_print_0(const u_char *bp, u_int length) 120 { 121 u_int len = length; 122 u_int16_t flags, prot; 123 124 flags = EXTRACT_16BITS(bp); 125 if (vflag) 126 printf(", Flags [%s]", 127 bittok2str(gre_flag_values,"none",flags)); 128 129 len -= 2; 130 bp += 2; 131 132 if (len < 2) 133 goto trunc; 134 prot = EXTRACT_16BITS(bp); 135 len -= 2; 136 bp += 2; 137 138 if ((flags & GRE_CP) | (flags & GRE_RP)) { 139 if (len < 2) 140 goto trunc; 141 if (vflag) 142 printf(", sum 0x%x", EXTRACT_16BITS(bp)); 143 bp += 2; 144 len -= 2; 145 146 if (len < 2) 147 goto trunc; 148 printf(", off 0x%x", EXTRACT_16BITS(bp)); 149 bp += 2; 150 len -= 2; 151 } 152 153 if (flags & GRE_KP) { 154 if (len < 4) 155 goto trunc; 156 printf(", key=0x%x", EXTRACT_32BITS(bp)); 157 bp += 4; 158 len -= 4; 159 } 160 161 if (flags & GRE_SP) { 162 if (len < 4) 163 goto trunc; 164 printf(", seq %u", EXTRACT_32BITS(bp)); 165 bp += 4; 166 len -= 4; 167 } 168 169 if (flags & GRE_RP) { 170 for (;;) { 171 u_int16_t af; 172 u_int8_t sreoff; 173 u_int8_t srelen; 174 175 if (len < 4) 176 goto trunc; 177 af = EXTRACT_16BITS(bp); 178 sreoff = *(bp + 2); 179 srelen = *(bp + 3); 180 bp += 4; 181 len -= 4; 182 183 if (af == 0 && srelen == 0) 184 break; 185 186 gre_sre_print(af, sreoff, srelen, bp, len); 187 188 if (len < srelen) 189 goto trunc; 190 bp += srelen; 191 len -= srelen; 192 } 193 } 194 195 if (eflag) 196 printf(", proto %s (0x%04x)", 197 tok2str(ethertype_values,"unknown",prot), 198 prot); 199 200 printf(", length %u",length); 201 202 if (vflag < 1) 203 printf(": "); /* put in a colon as protocol demarc */ 204 else 205 printf("\n\t"); /* if verbose go multiline */ 206 207 switch (prot) { 208 case ETHERTYPE_IP: 209 ip_print(gndo, bp, len); 210 break; 211 #ifdef INET6 212 case ETHERTYPE_IPV6: 213 ip6_print(bp, len); 214 break; 215 #endif 216 case ETHERTYPE_MPLS: 217 mpls_print(bp, len); 218 break; 219 case ETHERTYPE_IPX: 220 ipx_print(bp, len); 221 break; 222 case ETHERTYPE_ATALK: 223 atalk_print(bp, len); 224 break; 225 case ETHERTYPE_GRE_ISO: 226 isoclns_print(bp, len, len); 227 break; 228 case ETHERTYPE_TEB: 229 ether_print(bp, len, len, NULL, NULL); 230 break; 231 default: 232 printf("gre-proto-0x%x", prot); 233 } 234 return; 235 236 trunc: 237 printf("[|gre]"); 238 } 239 240 void 241 gre_print_1(const u_char *bp, u_int length) 242 { 243 u_int len = length; 244 u_int16_t flags, prot; 245 246 flags = EXTRACT_16BITS(bp); 247 len -= 2; 248 bp += 2; 249 250 if (vflag) 251 printf(", Flags [%s]", 252 bittok2str(gre_flag_values,"none",flags)); 253 254 if (len < 2) 255 goto trunc; 256 prot = EXTRACT_16BITS(bp); 257 len -= 2; 258 bp += 2; 259 260 261 if (flags & GRE_KP) { 262 u_int32_t k; 263 264 if (len < 4) 265 goto trunc; 266 k = EXTRACT_32BITS(bp); 267 printf(", call %d", k & 0xffff); 268 len -= 4; 269 bp += 4; 270 } 271 272 if (flags & GRE_SP) { 273 if (len < 4) 274 goto trunc; 275 printf(", seq %u", EXTRACT_32BITS(bp)); 276 bp += 4; 277 len -= 4; 278 } 279 280 if (flags & GRE_AP) { 281 if (len < 4) 282 goto trunc; 283 printf(", ack %u", EXTRACT_32BITS(bp)); 284 bp += 4; 285 len -= 4; 286 } 287 288 if ((flags & GRE_SP) == 0) 289 printf(", no-payload"); 290 291 if (eflag) 292 printf(", proto %s (0x%04x)", 293 tok2str(ethertype_values,"unknown",prot), 294 prot); 295 296 printf(", length %u",length); 297 298 if ((flags & GRE_SP) == 0) 299 return; 300 301 if (vflag < 1) 302 printf(": "); /* put in a colon as protocol demarc */ 303 else 304 printf("\n\t"); /* if verbose go multiline */ 305 306 switch (prot) { 307 case ETHERTYPE_PPP: 308 ppp_print(bp, len); 309 break; 310 default: 311 printf("gre-proto-0x%x", prot); 312 break; 313 } 314 return; 315 316 trunc: 317 printf("[|gre]"); 318 } 319 320 void 321 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen, 322 const u_char *bp, u_int len) 323 { 324 switch (af) { 325 case GRESRE_IP: 326 printf(", (rtaf=ip"); 327 gre_sre_ip_print(sreoff, srelen, bp, len); 328 printf(") "); 329 break; 330 case GRESRE_ASN: 331 printf(", (rtaf=asn"); 332 gre_sre_asn_print(sreoff, srelen, bp, len); 333 printf(") "); 334 break; 335 default: 336 printf(", (rtaf=0x%x) ", af); 337 } 338 } 339 void 340 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len) 341 { 342 struct in_addr a; 343 const u_char *up = bp; 344 345 if (sreoff & 3) { 346 printf(", badoffset=%u", sreoff); 347 return; 348 } 349 if (srelen & 3) { 350 printf(", badlength=%u", srelen); 351 return; 352 } 353 if (sreoff >= srelen) { 354 printf(", badoff/len=%u/%u", sreoff, srelen); 355 return; 356 } 357 358 for (;;) { 359 if (len < 4 || srelen == 0) 360 return; 361 362 memcpy(&a, bp, sizeof(a)); 363 printf(" %s%s", 364 ((bp - up) == sreoff) ? "*" : "", 365 inet_ntoa(a)); 366 367 bp += 4; 368 len -= 4; 369 srelen -= 4; 370 } 371 } 372 373 void 374 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len) 375 { 376 const u_char *up = bp; 377 378 if (sreoff & 1) { 379 printf(", badoffset=%u", sreoff); 380 return; 381 } 382 if (srelen & 1) { 383 printf(", badlength=%u", srelen); 384 return; 385 } 386 if (sreoff >= srelen) { 387 printf(", badoff/len=%u/%u", sreoff, srelen); 388 return; 389 } 390 391 for (;;) { 392 if (len < 2 || srelen == 0) 393 return; 394 395 printf(" %s%x", 396 ((bp - up) == sreoff) ? "*" : "", 397 EXTRACT_16BITS(bp)); 398 399 bp += 2; 400 len -= 2; 401 srelen -= 2; 402 } 403 } 404