1 /* 2 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that: (1) source code distributions 7 * retain the above copyright notice and this paragraph in its entirety, (2) 8 * distributions including binary code include the above copyright notice and 9 * this paragraph in its entirety in the documentation or other materials 10 * provided with the distribution, and (3) all advertising materials mentioning 11 * features or use of this software display the following acknowledgement: 12 * ``This product includes software developed by the University of California, 13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 14 * the University nor the names of its contributors may be used to endorse 15 * or promote products derived from this software without specific prior 16 * written permission. 17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 20 */ 21 22 /* \summary: IPv6 printer */ 23 24 #ifdef HAVE_CONFIG_H 25 #include <config.h> 26 #endif 27 28 #include "netdissect-stdinc.h" 29 30 #include <string.h> 31 32 #include "netdissect.h" 33 #include "addrtoname.h" 34 #include "extract.h" 35 36 #include "ip6.h" 37 #include "ipproto.h" 38 39 /* 40 * If routing headers are presend and valid, set dst to the final destination. 41 * Otherwise, set it to the IPv6 destination. 42 * 43 * This is used for UDP and TCP pseudo-header in the checksum 44 * calculation. 45 */ 46 static void 47 ip6_finddst(netdissect_options *ndo, nd_ipv6 *dst, 48 const struct ip6_hdr *ip6) 49 { 50 const u_char *cp; 51 u_int advance; 52 u_int nh; 53 const void *dst_addr; 54 const struct ip6_rthdr *dp; 55 const struct ip6_rthdr0 *dp0; 56 const struct ip6_srh *srh; 57 const u_char *p; 58 int i, len; 59 60 cp = (const u_char *)ip6; 61 advance = sizeof(struct ip6_hdr); 62 nh = GET_U_1(ip6->ip6_nxt); 63 dst_addr = (const void *)ip6->ip6_dst; 64 65 while (cp < ndo->ndo_snapend) { 66 cp += advance; 67 68 switch (nh) { 69 70 case IPPROTO_HOPOPTS: 71 case IPPROTO_DSTOPTS: 72 case IPPROTO_MOBILITY_OLD: 73 case IPPROTO_MOBILITY: 74 /* 75 * These have a header length byte, following 76 * the next header byte, giving the length of 77 * the header, in units of 8 octets, excluding 78 * the first 8 octets. 79 */ 80 advance = (GET_U_1(cp + 1) + 1) << 3; 81 nh = GET_U_1(cp); 82 break; 83 84 case IPPROTO_FRAGMENT: 85 /* 86 * The byte following the next header byte is 87 * marked as reserved, and the header is always 88 * the same size. 89 */ 90 advance = sizeof(struct ip6_frag); 91 nh = GET_U_1(cp); 92 break; 93 94 case IPPROTO_ROUTING: 95 /* 96 * OK, we found it. 97 */ 98 dp = (const struct ip6_rthdr *)cp; 99 ND_TCHECK_SIZE(dp); 100 len = GET_U_1(dp->ip6r_len); 101 switch (GET_U_1(dp->ip6r_type)) { 102 103 case IPV6_RTHDR_TYPE_0: 104 case IPV6_RTHDR_TYPE_2: /* Mobile IPv6 ID-20 */ 105 dp0 = (const struct ip6_rthdr0 *)dp; 106 if (len % 2 == 1) 107 goto trunc; 108 len >>= 1; 109 p = (const u_char *) dp0->ip6r0_addr; 110 for (i = 0; i < len; i++) { 111 ND_TCHECK_16(p); 112 dst_addr = (const void *)p; 113 p += 16; 114 } 115 break; 116 case IPV6_RTHDR_TYPE_4: 117 /* IPv6 Segment Routing Header (SRH) */ 118 srh = (const struct ip6_srh *)dp; 119 if (len % 2 == 1) 120 goto trunc; 121 p = (const u_char *) srh->srh_segments; 122 /* 123 * The list of segments are encoded in the reverse order. 124 * Accordingly, the final DA is encoded in srh_segments[0] 125 */ 126 ND_TCHECK_16(p); 127 dst_addr = (const void *)p; 128 break; 129 130 default: 131 break; 132 } 133 134 /* 135 * Only one routing header to a customer. 136 */ 137 goto done; 138 139 case IPPROTO_AH: 140 case IPPROTO_ESP: 141 case IPPROTO_IPCOMP: 142 default: 143 /* 144 * AH and ESP are, in the RFCs that describe them, 145 * described as being "viewed as an end-to-end 146 * payload" "in the IPv6 context, so that they 147 * "should appear after hop-by-hop, routing, and 148 * fragmentation extension headers". We assume 149 * that's the case, and stop as soon as we see 150 * one. (We can't handle an ESP header in 151 * the general case anyway, as its length depends 152 * on the encryption algorithm.) 153 * 154 * IPComp is also "viewed as an end-to-end 155 * payload" "in the IPv6 context". 156 * 157 * All other protocols are assumed to be the final 158 * protocol. 159 */ 160 goto done; 161 } 162 } 163 164 done: 165 trunc: 166 GET_CPY_BYTES(dst, dst_addr, sizeof(nd_ipv6)); 167 } 168 169 /* 170 * Compute a V6-style checksum by building a pseudoheader. 171 */ 172 uint16_t 173 nextproto6_cksum(netdissect_options *ndo, 174 const struct ip6_hdr *ip6, const uint8_t *data, 175 u_int len, u_int covlen, uint8_t next_proto) 176 { 177 struct { 178 nd_ipv6 ph_src; 179 nd_ipv6 ph_dst; 180 uint32_t ph_len; 181 uint8_t ph_zero[3]; 182 uint8_t ph_nxt; 183 } ph; 184 struct cksum_vec vec[2]; 185 u_int nh; 186 187 /* pseudo-header */ 188 memset(&ph, 0, sizeof(ph)); 189 GET_CPY_BYTES(&ph.ph_src, ip6->ip6_src, sizeof(nd_ipv6)); 190 nh = GET_U_1(ip6->ip6_nxt); 191 switch (nh) { 192 193 case IPPROTO_HOPOPTS: 194 case IPPROTO_DSTOPTS: 195 case IPPROTO_MOBILITY_OLD: 196 case IPPROTO_MOBILITY: 197 case IPPROTO_FRAGMENT: 198 case IPPROTO_ROUTING: 199 /* 200 * The next header is either a routing header or a header 201 * after which there might be a routing header, so scan 202 * for a routing header. 203 */ 204 ip6_finddst(ndo, &ph.ph_dst, ip6); 205 break; 206 207 default: 208 GET_CPY_BYTES(&ph.ph_dst, ip6->ip6_dst, sizeof(nd_ipv6)); 209 break; 210 } 211 ph.ph_len = htonl(len); 212 ph.ph_nxt = next_proto; 213 214 vec[0].ptr = (const uint8_t *)(void *)&ph; 215 vec[0].len = sizeof(ph); 216 vec[1].ptr = data; 217 vec[1].len = covlen; 218 219 return in_cksum(vec, 2); 220 } 221 222 /* 223 * print an IP6 datagram. 224 */ 225 void 226 ip6_print(netdissect_options *ndo, const u_char *bp, u_int length) 227 { 228 const struct ip6_hdr *ip6; 229 int advance; 230 u_int len; 231 u_int total_advance; 232 const u_char *cp; 233 uint32_t payload_len; 234 uint8_t nh; 235 int fragmented = 0; 236 u_int flow; 237 int found_extension_header; 238 int found_jumbo; 239 240 ndo->ndo_protocol = "ip6"; 241 ip6 = (const struct ip6_hdr *)bp; 242 243 ND_TCHECK_SIZE(ip6); 244 if (length < sizeof (struct ip6_hdr)) { 245 ND_PRINT("truncated-ip6 %u", length); 246 return; 247 } 248 249 if (!ndo->ndo_eflag) 250 ND_PRINT("IP6 "); 251 252 if (IP6_VERSION(ip6) != 6) { 253 ND_PRINT("version error: %u != 6", IP6_VERSION(ip6)); 254 return; 255 } 256 257 payload_len = GET_BE_U_2(ip6->ip6_plen); 258 /* 259 * RFC 1883 says: 260 * 261 * The Payload Length field in the IPv6 header must be set to zero 262 * in every packet that carries the Jumbo Payload option. If a 263 * packet is received with a valid Jumbo Payload option present and 264 * a non-zero IPv6 Payload Length field, an ICMP Parameter Problem 265 * message, Code 0, should be sent to the packet's source, pointing 266 * to the Option Type field of the Jumbo Payload option. 267 * 268 * Later versions of the IPv6 spec don't discuss the Jumbo Payload 269 * option. 270 * 271 * If the payload length is 0, we temporarily just set the total 272 * length to the remaining data in the packet (which, for Ethernet, 273 * could include frame padding, but if it's a Jumbo Payload frame, 274 * it shouldn't even be sendable over Ethernet, so we don't worry 275 * about that), so we can process the extension headers in order 276 * to *find* a Jumbo Payload hop-by-hop option and, when we've 277 * processed all the extension headers, check whether we found 278 * a Jumbo Payload option, and fail if we haven't. 279 */ 280 if (payload_len != 0) { 281 len = payload_len + sizeof(struct ip6_hdr); 282 if (length < len) 283 ND_PRINT("truncated-ip6 - %u bytes missing!", 284 len - length); 285 } else 286 len = length + sizeof(struct ip6_hdr); 287 288 nh = GET_U_1(ip6->ip6_nxt); 289 if (ndo->ndo_vflag) { 290 flow = GET_BE_U_4(ip6->ip6_flow); 291 ND_PRINT("("); 292 #if 0 293 /* rfc1883 */ 294 if (flow & 0x0f000000) 295 ND_PRINT("pri 0x%02x, ", (flow & 0x0f000000) >> 24); 296 if (flow & 0x00ffffff) 297 ND_PRINT("flowlabel 0x%06x, ", flow & 0x00ffffff); 298 #else 299 /* RFC 2460 */ 300 if (flow & 0x0ff00000) 301 ND_PRINT("class 0x%02x, ", (flow & 0x0ff00000) >> 20); 302 if (flow & 0x000fffff) 303 ND_PRINT("flowlabel 0x%05x, ", flow & 0x000fffff); 304 #endif 305 306 ND_PRINT("hlim %u, next-header %s (%u) payload length: %u) ", 307 GET_U_1(ip6->ip6_hlim), 308 tok2str(ipproto_values,"unknown",nh), 309 nh, 310 payload_len); 311 } 312 313 /* 314 * Cut off the snapshot length to the end of the IP payload. 315 */ 316 nd_push_snapend(ndo, bp + len); 317 318 cp = (const u_char *)ip6; 319 advance = sizeof(struct ip6_hdr); 320 total_advance = 0; 321 /* Process extension headers */ 322 found_extension_header = 0; 323 found_jumbo = 0; 324 while (cp < ndo->ndo_snapend && advance > 0) { 325 if (len < (u_int)advance) 326 goto trunc; 327 cp += advance; 328 len -= advance; 329 total_advance += advance; 330 331 if (cp == (const u_char *)(ip6 + 1) && 332 nh != IPPROTO_TCP && nh != IPPROTO_UDP && 333 nh != IPPROTO_DCCP && nh != IPPROTO_SCTP) { 334 ND_PRINT("%s > %s: ", GET_IP6ADDR_STRING(ip6->ip6_src), 335 GET_IP6ADDR_STRING(ip6->ip6_dst)); 336 } 337 338 switch (nh) { 339 340 case IPPROTO_HOPOPTS: 341 advance = hbhopt_process(ndo, cp, &found_jumbo, &payload_len); 342 if (advance < 0) { 343 nd_pop_packet_info(ndo); 344 return; 345 } 346 found_extension_header = 1; 347 nh = GET_U_1(cp); 348 break; 349 350 case IPPROTO_DSTOPTS: 351 advance = dstopt_process(ndo, cp); 352 if (advance < 0) { 353 nd_pop_packet_info(ndo); 354 return; 355 } 356 found_extension_header = 1; 357 nh = GET_U_1(cp); 358 break; 359 360 case IPPROTO_FRAGMENT: 361 advance = frag6_print(ndo, cp, (const u_char *)ip6); 362 if (advance < 0 || ndo->ndo_snapend <= cp + advance) { 363 nd_pop_packet_info(ndo); 364 return; 365 } 366 found_extension_header = 1; 367 nh = GET_U_1(cp); 368 fragmented = 1; 369 break; 370 371 case IPPROTO_MOBILITY_OLD: 372 case IPPROTO_MOBILITY: 373 /* 374 * XXX - we don't use "advance"; RFC 3775 says that 375 * the next header field in a mobility header 376 * should be IPPROTO_NONE, but speaks of 377 * the possibility of a future extension in 378 * which payload can be piggybacked atop a 379 * mobility header. 380 */ 381 advance = mobility_print(ndo, cp, (const u_char *)ip6); 382 if (advance < 0) { 383 nd_pop_packet_info(ndo); 384 return; 385 } 386 found_extension_header = 1; 387 nh = GET_U_1(cp); 388 nd_pop_packet_info(ndo); 389 return; 390 391 case IPPROTO_ROUTING: 392 ND_TCHECK_1(cp); 393 advance = rt6_print(ndo, cp, (const u_char *)ip6); 394 if (advance < 0) { 395 nd_pop_packet_info(ndo); 396 return; 397 } 398 found_extension_header = 1; 399 nh = GET_U_1(cp); 400 break; 401 402 default: 403 /* 404 * Not an extension header; hand off to the 405 * IP protocol demuxer. 406 */ 407 if (found_jumbo) { 408 /* 409 * We saw a Jumbo Payload option. 410 * Set the length to the payload length 411 * plus the IPv6 header length, and 412 * change the snapshot length accordingly. 413 * 414 * But make sure it's not shorter than 415 * the total number of bytes we've 416 * processed so far. 417 */ 418 len = payload_len + sizeof(struct ip6_hdr); 419 if (len < total_advance) 420 goto trunc; 421 if (length < len) 422 ND_PRINT("truncated-ip6 - %u bytes missing!", 423 len - length); 424 nd_change_snapend(ndo, bp + len); 425 426 /* 427 * Now subtract the length of the IPv6 428 * header plus extension headers to get 429 * the payload length. 430 */ 431 len -= total_advance; 432 } else { 433 /* 434 * We didn't see a Jumbo Payload option; 435 * was the payload length zero? 436 */ 437 if (payload_len == 0) { 438 /* 439 * Yes. If we found an extension 440 * header, treat that as a truncated 441 * packet header, as there was 442 * no payload to contain an 443 * extension header. 444 */ 445 if (found_extension_header) 446 goto trunc; 447 448 /* 449 * OK, we didn't see any extnesion 450 * header, but that means we have 451 * no payload, so set the length 452 * to the IPv6 header length, 453 * and change the snapshot length 454 * accordingly. 455 */ 456 len = sizeof(struct ip6_hdr); 457 nd_change_snapend(ndo, bp + len); 458 459 /* 460 * Now subtract the length of 461 * the IPv6 header plus extension 462 * headers (there weren't any, so 463 * that's just the IPv6 header 464 * length) to get the payload length. 465 */ 466 len -= total_advance; 467 } 468 } 469 ip_demux_print(ndo, cp, len, 6, fragmented, 470 GET_U_1(ip6->ip6_hlim), nh, bp); 471 nd_pop_packet_info(ndo); 472 return; 473 } 474 475 /* ndo_protocol reassignment after xxx_print() calls */ 476 ndo->ndo_protocol = "ip6"; 477 } 478 479 nd_pop_packet_info(ndo); 480 return; 481 trunc: 482 nd_print_trunc(ndo); 483 } 484