1 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 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. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/socket.h> 37 38 #include <netinet/in.h> 39 #include <netinet/ip6.h> 40 41 #include <string.h> 42 #include <stdio.h> 43 44 static int ip6optlen(u_int8_t *opt, u_int8_t *lim); 45 static void inet6_insert_padopt(u_char *p, int len); 46 47 #ifndef IPV6_2292HOPOPTS 48 #define IPV6_2292HOPOPTS 22 49 #endif 50 #ifndef IPV6_2292DSTOPTS 51 #define IPV6_2292DSTOPTS 23 52 #endif 53 54 #define is_ipv6_hopopts(x) \ 55 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS) 56 #define is_ipv6_dstopts(x) \ 57 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS) 58 59 /* 60 * This function returns the number of bytes required to hold an option 61 * when it is stored as ancillary data, including the cmsghdr structure 62 * at the beginning, and any padding at the end (to make its size a 63 * multiple of 8 bytes). The argument is the size of the structure 64 * defining the option, which must include any pad bytes at the 65 * beginning (the value y in the alignment term "xn + y"), the type 66 * byte, the length byte, and the option data. 67 */ 68 int 69 inet6_option_space(int nbytes) 70 { 71 nbytes += 2; /* we need space for nxt-hdr and length fields */ 72 return(CMSG_SPACE((nbytes + 7) & ~7)); 73 } 74 75 /* 76 * This function is called once per ancillary data object that will 77 * contain either Hop-by-Hop or Destination options. It returns 0 on 78 * success or -1 on an error. 79 */ 80 int 81 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type) 82 { 83 struct cmsghdr *ch = (struct cmsghdr *)bp; 84 85 /* argument validation */ 86 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type)) 87 return(-1); 88 89 ch->cmsg_level = IPPROTO_IPV6; 90 ch->cmsg_type = type; 91 ch->cmsg_len = CMSG_LEN(0); 92 93 *cmsgp = ch; 94 return(0); 95 } 96 97 /* 98 * This function appends a Hop-by-Hop option or a Destination option 99 * into an ancillary data object that has been initialized by 100 * inet6_option_init(). This function returns 0 if it succeeds or -1 on 101 * an error. 102 * multx is the value x in the alignment term "xn + y" described 103 * earlier. It must have a value of 1, 2, 4, or 8. 104 * plusy is the value y in the alignment term "xn + y" described 105 * earlier. It must have a value between 0 and 7, inclusive. 106 */ 107 int 108 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx, 109 int plusy) 110 { 111 int padlen, optlen, off; 112 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len; 113 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 114 115 /* argument validation */ 116 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 117 return(-1); 118 if (plusy < 0 || plusy > 7) 119 return(-1); 120 121 /* 122 * If this is the first option, allocate space for the 123 * first 2 bytes(for next header and length fields) of 124 * the option header. 125 */ 126 if (bp == (u_char *)eh) { 127 bp += 2; 128 cmsg->cmsg_len += 2; 129 } 130 131 /* calculate pad length before the option. */ 132 off = bp - (u_char *)eh; 133 padlen = roundup2(off % multx, multx) - (off % multx); 134 padlen += plusy; 135 padlen %= multx; /* keep the pad as short as possible */ 136 /* insert padding */ 137 inet6_insert_padopt(bp, padlen); 138 cmsg->cmsg_len += padlen; 139 bp += padlen; 140 141 /* copy the option */ 142 if (typep[0] == IP6OPT_PAD1) 143 optlen = 1; 144 else 145 optlen = typep[1] + 2; 146 memcpy(bp, typep, optlen); 147 bp += optlen; 148 cmsg->cmsg_len += optlen; 149 150 /* calculate pad length after the option and insert the padding */ 151 off = bp - (u_char *)eh; 152 padlen = ((off + 7) & ~7) - off; 153 inet6_insert_padopt(bp, padlen); 154 bp += padlen; 155 cmsg->cmsg_len += padlen; 156 157 /* update the length field of the ip6 option header */ 158 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 159 160 return(0); 161 } 162 163 /* 164 * This function appends a Hop-by-Hop option or a Destination option 165 * into an ancillary data object that has been initialized by 166 * inet6_option_init(). This function returns a pointer to the 8-bit 167 * option type field that starts the option on success, or NULL on an 168 * error. 169 * The difference between this function and inet6_option_append() is 170 * that the latter copies the contents of a previously built option into 171 * the ancillary data object while the current function returns a 172 * pointer to the space in the data object where the option's TLV must 173 * then be built by the caller. 174 * 175 */ 176 u_int8_t * 177 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy) 178 { 179 int padlen, off; 180 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 181 u_int8_t *retval; 182 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 183 184 /* argument validation */ 185 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 186 return(NULL); 187 if (plusy < 0 || plusy > 7) 188 return(NULL); 189 190 /* 191 * If this is the first option, allocate space for the 192 * first 2 bytes(for next header and length fields) of 193 * the option header. 194 */ 195 if (bp == (u_char *)eh) { 196 bp += 2; 197 cmsg->cmsg_len += 2; 198 } 199 200 /* calculate pad length before the option. */ 201 off = bp - (u_char *)eh; 202 padlen = roundup2(off % multx, multx) - (off % multx); 203 padlen += plusy; 204 padlen %= multx; /* keep the pad as short as possible */ 205 /* insert padding */ 206 inet6_insert_padopt(bp, padlen); 207 cmsg->cmsg_len += padlen; 208 bp += padlen; 209 210 /* keep space to store specified length of data */ 211 retval = bp; 212 bp += datalen; 213 cmsg->cmsg_len += datalen; 214 215 /* calculate pad length after the option and insert the padding */ 216 off = bp - (u_char *)eh; 217 padlen = ((off + 7) & ~7) - off; 218 inet6_insert_padopt(bp, padlen); 219 bp += padlen; 220 cmsg->cmsg_len += padlen; 221 222 /* update the length field of the ip6 option header */ 223 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 224 225 return(retval); 226 } 227 228 /* 229 * This function processes the next Hop-by-Hop option or Destination 230 * option in an ancillary data object. If another option remains to be 231 * processed, the return value of the function is 0 and *tptrp points to 232 * the 8-bit option type field (which is followed by the 8-bit option 233 * data length, followed by the option data). If no more options remain 234 * to be processed, the return value is -1 and *tptrp is NULL. If an 235 * error occurs, the return value is -1 and *tptrp is not NULL. 236 * (RFC 2292, 6.3.5) 237 */ 238 int 239 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp) 240 { 241 struct ip6_ext *ip6e; 242 int hdrlen, optlen; 243 u_int8_t *lim; 244 245 if (cmsg->cmsg_level != IPPROTO_IPV6 || 246 (!is_ipv6_hopopts(cmsg->cmsg_type) && 247 !is_ipv6_dstopts(cmsg->cmsg_type))) 248 return(-1); 249 250 /* message length validation */ 251 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 252 return(-1); 253 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 254 hdrlen = (ip6e->ip6e_len + 1) << 3; 255 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 256 return(-1); 257 258 /* 259 * If the caller does not specify the starting point, 260 * simply return the 1st option. 261 * Otherwise, search the option list for the next option. 262 */ 263 lim = (u_int8_t *)ip6e + hdrlen; 264 if (*tptrp == NULL) 265 *tptrp = (u_int8_t *)(ip6e + 1); 266 else { 267 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 268 return(-1); 269 270 *tptrp = *tptrp + optlen; 271 } 272 if (*tptrp >= lim) { /* there is no option */ 273 *tptrp = NULL; 274 return(-1); 275 } 276 /* 277 * Finally, checks if the next option is safely stored in the 278 * cmsg data. 279 */ 280 if (ip6optlen(*tptrp, lim) == 0) 281 return(-1); 282 else 283 return(0); 284 } 285 286 /* 287 * This function is similar to the inet6_option_next() function, 288 * except this function lets the caller specify the option type to be 289 * searched for, instead of always returning the next option in the 290 * ancillary data object. 291 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 292 * it's a typo. The variable should be type of u_int8_t **. 293 */ 294 int 295 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type) 296 { 297 struct ip6_ext *ip6e; 298 int hdrlen, optlen; 299 u_int8_t *optp, *lim; 300 301 if (cmsg->cmsg_level != IPPROTO_IPV6 || 302 (!is_ipv6_hopopts(cmsg->cmsg_type) && 303 !is_ipv6_dstopts(cmsg->cmsg_type))) 304 return(-1); 305 306 /* message length validation */ 307 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 308 return(-1); 309 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 310 hdrlen = (ip6e->ip6e_len + 1) << 3; 311 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 312 return(-1); 313 314 /* 315 * If the caller does not specify the starting point, 316 * search from the beginning of the option list. 317 * Otherwise, search from *the next option* of the specified point. 318 */ 319 lim = (u_int8_t *)ip6e + hdrlen; 320 if (*tptrp == NULL) 321 *tptrp = (u_int8_t *)(ip6e + 1); 322 else { 323 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 324 return(-1); 325 326 *tptrp = *tptrp + optlen; 327 } 328 for (optp = *tptrp; optp < lim; optp += optlen) { 329 if (*optp == type) { 330 *tptrp = optp; 331 return(0); 332 } 333 if ((optlen = ip6optlen(optp, lim)) == 0) 334 return(-1); 335 } 336 337 /* search failed */ 338 *tptrp = NULL; 339 return(-1); 340 } 341 342 /* 343 * Calculate the length of a given IPv6 option. Also checks 344 * if the option is safely stored in user's buffer according to the 345 * calculated length and the limitation of the buffer. 346 */ 347 static int 348 ip6optlen(u_int8_t *opt, u_int8_t *lim) 349 { 350 int optlen; 351 352 if (*opt == IP6OPT_PAD1) 353 optlen = 1; 354 else { 355 /* is there enough space to store type and len? */ 356 if (opt + 2 > lim) 357 return(0); 358 optlen = *(opt + 1) + 2; 359 } 360 if (opt + optlen <= lim) 361 return(optlen); 362 363 return(0); 364 } 365 366 static void 367 inet6_insert_padopt(u_char *p, int len) 368 { 369 switch(len) { 370 case 0: 371 return; 372 case 1: 373 p[0] = IP6OPT_PAD1; 374 return; 375 default: 376 p[0] = IP6OPT_PADN; 377 p[1] = len - 2; 378 memset(&p[2], 0, len - 2); 379 return; 380 } 381 } 382 383 /* 384 * The following functions are defined in RFC3542, which is a successor 385 * of RFC2292. 386 */ 387 388 int 389 inet6_opt_init(void *extbuf, socklen_t extlen) 390 { 391 struct ip6_ext *ext = (struct ip6_ext *)extbuf; 392 393 if (ext) { 394 if (extlen <= 0 || (extlen % 8)) 395 return(-1); 396 ext->ip6e_len = (extlen >> 3) - 1; 397 } 398 399 return(2); /* sizeof the next and the length fields */ 400 } 401 402 int 403 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type, 404 socklen_t len, u_int8_t align, void **databufp) 405 { 406 int currentlen = offset, padlen = 0; 407 408 /* 409 * The option type must have a value from 2 to 255, inclusive. 410 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.) 411 */ 412 if (type < 2) 413 return(-1); 414 415 /* 416 * The option data length must have a value between 0 and 255, 417 * inclusive, and is the length of the option data that follows. 418 */ 419 if (len > 255 || len < 0 ) 420 return(-1); 421 422 /* 423 * The align parameter must have a value of 1, 2, 4, or 8. 424 * The align value can not exceed the value of len. 425 */ 426 if (align != 1 && align != 2 && align != 4 && align != 8) 427 return(-1); 428 if (align > len) 429 return(-1); 430 431 /* Calculate the padding length. */ 432 currentlen += 2 + len; /* 2 means "type + len" */ 433 if (currentlen % align) 434 padlen = align - (currentlen % align); 435 436 /* The option must fit in the extension header buffer. */ 437 currentlen += padlen; 438 if (extlen && /* XXX: right? */ 439 currentlen > extlen) 440 return(-1); 441 442 if (extbuf) { 443 u_int8_t *optp = (u_int8_t *)extbuf + offset; 444 445 if (padlen == 1) { 446 /* insert a Pad1 option */ 447 *optp = IP6OPT_PAD1; 448 optp++; 449 } 450 else if (padlen > 0) { 451 /* insert a PadN option for alignment */ 452 *optp++ = IP6OPT_PADN; 453 *optp++ = padlen - 2; 454 memset(optp, 0, padlen - 2); 455 optp += (padlen - 2); 456 } 457 458 *optp++ = type; 459 *optp++ = len; 460 461 *databufp = optp; 462 } 463 464 return(currentlen); 465 } 466 467 int 468 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset) 469 { 470 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0; 471 472 if (extbuf) { 473 u_int8_t *padp; 474 int padlen = updatelen - offset; 475 476 if (updatelen > extlen) 477 return(-1); 478 479 padp = (u_int8_t *)extbuf + offset; 480 if (padlen == 1) 481 *padp = IP6OPT_PAD1; 482 else if (padlen > 0) { 483 *padp++ = IP6OPT_PADN; 484 *padp++ = (padlen - 2); 485 memset(padp, 0, padlen - 2); 486 } 487 } 488 489 return(updatelen); 490 } 491 492 int 493 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen) 494 { 495 496 memcpy((u_int8_t *)databuf + offset, val, vallen); 497 return(offset + vallen); 498 } 499 500 int 501 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep, 502 socklen_t *lenp, void **databufp) 503 { 504 u_int8_t *optp, *lim; 505 int optlen; 506 507 /* Validate extlen. XXX: is the variable really necessary?? */ 508 if (extlen == 0 || (extlen % 8)) 509 return(-1); 510 lim = (u_int8_t *)extbuf + extlen; 511 512 /* 513 * If this is the first time this function called for this options 514 * header, simply return the 1st option. 515 * Otherwise, search the option list for the next option. 516 */ 517 if (offset == 0) { 518 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1); 519 } 520 else 521 optp = (u_int8_t *)extbuf + offset; 522 523 /* Find the next option skipping any padding options. */ 524 while(optp < lim) { 525 switch(*optp) { 526 case IP6OPT_PAD1: 527 optp++; 528 break; 529 case IP6OPT_PADN: 530 if ((optlen = ip6optlen(optp, lim)) == 0) 531 goto optend; 532 optp += optlen; 533 break; 534 default: /* found */ 535 if ((optlen = ip6optlen(optp, lim)) == 0) 536 goto optend; 537 *typep = *optp; 538 *lenp = optlen - 2; 539 *databufp = optp + 2; 540 return(optp + optlen - (u_int8_t *)extbuf); 541 } 542 } 543 544 optend: 545 *databufp = NULL; /* for safety */ 546 return(-1); 547 } 548 549 int 550 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type, 551 socklen_t *lenp, void **databufp) 552 { 553 u_int8_t *optp, *lim; 554 int optlen; 555 556 /* Validate extlen. XXX: is the variable really necessary?? */ 557 if (extlen == 0 || (extlen % 8)) 558 return(-1); 559 lim = (u_int8_t *)extbuf + extlen; 560 561 /* 562 * If this is the first time this function called for this options 563 * header, simply return the 1st option. 564 * Otherwise, search the option list for the next option. 565 */ 566 if (offset == 0) { 567 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1); 568 } 569 else 570 optp = (u_int8_t *)extbuf + offset; 571 572 /* Find the specified option */ 573 while(optp < lim) { 574 if ((optlen = ip6optlen(optp, lim)) == 0) 575 goto optend; 576 577 if (*optp == type) { /* found */ 578 *lenp = optlen - 2; 579 *databufp = optp + 2; 580 return(optp + optlen - (u_int8_t *)extbuf); 581 } 582 583 optp += optlen; 584 } 585 586 optend: 587 *databufp = NULL; /* for safety */ 588 return(-1); 589 } 590 591 int 592 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen) 593 { 594 595 /* we can't assume alignment here */ 596 memcpy(val, (u_int8_t *)databuf + offset, vallen); 597 598 return(offset + vallen); 599 } 600