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 (at) 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 default: 229 printf("gre-proto-0x%x", prot); 230 } 231 return; 232 233 trunc: 234 printf("[|gre]"); 235 } 236 237 void 238 gre_print_1(const u_char *bp, u_int length) 239 { 240 u_int len = length; 241 u_int16_t flags, prot; 242 243 flags = EXTRACT_16BITS(bp); 244 len -= 2; 245 bp += 2; 246 247 if (vflag) 248 printf(", Flags [%s]", 249 bittok2str(gre_flag_values,"none",flags)); 250 251 if (len < 2) 252 goto trunc; 253 prot = EXTRACT_16BITS(bp); 254 len -= 2; 255 bp += 2; 256 257 258 if (flags & GRE_KP) { 259 u_int32_t k; 260 261 if (len < 4) 262 goto trunc; 263 k = EXTRACT_32BITS(bp); 264 printf(", call %d", k & 0xffff); 265 len -= 4; 266 bp += 4; 267 } 268 269 if (flags & GRE_SP) { 270 if (len < 4) 271 goto trunc; 272 printf(", seq %u", EXTRACT_32BITS(bp)); 273 bp += 4; 274 len -= 4; 275 } 276 277 if (flags & GRE_AP) { 278 if (len < 4) 279 goto trunc; 280 printf(", ack %u", EXTRACT_32BITS(bp)); 281 bp += 4; 282 len -= 4; 283 } 284 285 if ((flags & GRE_SP) == 0) 286 printf(", no-payload"); 287 288 if (eflag) 289 printf(", proto %s (0x%04x)", 290 tok2str(ethertype_values,"unknown",prot), 291 prot); 292 293 printf(", length %u",length); 294 295 if ((flags & GRE_SP) == 0) 296 return; 297 298 if (vflag < 1) 299 printf(": "); /* put in a colon as protocol demarc */ 300 else 301 printf("\n\t"); /* if verbose go multiline */ 302 303 switch (prot) { 304 case ETHERTYPE_PPP: 305 ppp_print(bp, len); 306 break; 307 default: 308 printf("gre-proto-0x%x", prot); 309 break; 310 } 311 return; 312 313 trunc: 314 printf("[|gre]"); 315 } 316 317 void 318 gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen, 319 const u_char *bp, u_int len) 320 { 321 switch (af) { 322 case GRESRE_IP: 323 printf(", (rtaf=ip"); 324 gre_sre_ip_print(sreoff, srelen, bp, len); 325 printf(") "); 326 break; 327 case GRESRE_ASN: 328 printf(", (rtaf=asn"); 329 gre_sre_asn_print(sreoff, srelen, bp, len); 330 printf(") "); 331 break; 332 default: 333 printf(", (rtaf=0x%x) ", af); 334 } 335 } 336 void 337 gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, 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 printf(", badoffset=%u", sreoff); 344 return; 345 } 346 if (srelen & 3) { 347 printf(", badlength=%u", srelen); 348 return; 349 } 350 if (sreoff >= srelen) { 351 printf(", 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 printf(" %s%s", 361 ((bp - up) == sreoff) ? "*" : "", 362 inet_ntoa(a)); 363 364 bp += 4; 365 len -= 4; 366 srelen -= 4; 367 } 368 } 369 370 void 371 gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len) 372 { 373 const u_char *up = bp; 374 375 if (sreoff & 1) { 376 printf(", badoffset=%u", sreoff); 377 return; 378 } 379 if (srelen & 1) { 380 printf(", badlength=%u", srelen); 381 return; 382 } 383 if (sreoff >= srelen) { 384 printf(", badoff/len=%u/%u", sreoff, srelen); 385 return; 386 } 387 388 for (;;) { 389 if (len < 2 || srelen == 0) 390 return; 391 392 printf(" %s%x", 393 ((bp - up) == sreoff) ? "*" : "", 394 EXTRACT_16BITS(bp)); 395 396 bp += 2; 397 len -= 2; 398 srelen -= 2; 399 } 400 } 401
