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 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.8.10.2.2.1 2010/06/14 02:09:06 kensmith Exp $ 32 */ 33 34/* 35 * These routines support RFC 3542 36 * __APPLE_USE_RFC_3542 selects the appropriate API in <netinet6/in6.h> 37 */ 38#define __APPLE_USE_RFC_3542 39 40#include <sys/cdefs.h> 41 42#include <sys/param.h> 43#include <sys/types.h> 44#include <sys/socket.h> 45 46#include <netinet/in.h> 47#include <netinet/ip6.h> 48 49#include <string.h> 50#include <stdio.h> 51 52static int ip6optlen(u_int8_t *opt, u_int8_t *lim); 53static void inet6_insert_padopt(u_char *p, int len); 54 55/* 56 * This function returns the number of bytes required to hold an option 57 * when it is stored as ancillary data, including the cmsghdr structure 58 * at the beginning, and any padding at the end (to make its size a 59 * multiple of 8 bytes). The argument is the size of the structure 60 * defining the option, which must include any pad bytes at the 61 * beginning (the value y in the alignment term "xn + y"), the type 62 * byte, the length byte, and the option data. 63 */ 64int 65inet6_option_space(int nbytes) 66{ 67 nbytes += 2; /* we need space for nxt-hdr and length fields */ 68 return(CMSG_SPACE((nbytes + 7) & ~7)); 69} 70 71/* 72 * This function is called once per ancillary data object that will 73 * contain either Hop-by-Hop or Destination options. It returns 0 on 74 * success or -1 on an error. 75 */ 76int 77inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type) 78{ 79 struct cmsghdr *ch = (struct cmsghdr *)bp; 80 81 /* argument validation */ 82 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS) 83 return(-1); 84 85 ch->cmsg_level = IPPROTO_IPV6; 86 ch->cmsg_type = type; 87 ch->cmsg_len = CMSG_LEN(0); 88 89 *cmsgp = ch; 90 return(0); 91} 92 93/* 94 * This function appends a Hop-by-Hop option or a Destination option 95 * into an ancillary data object that has been initialized by 96 * inet6_option_init(). This function returns 0 if it succeeds or -1 on 97 * an error. 98 * multx is the value x in the alignment term "xn + y" described 99 * earlier. It must have a value of 1, 2, 4, or 8. 100 * plusy is the value y in the alignment term "xn + y" described 101 * earlier. It must have a value between 0 and 7, inclusive. 102 */ 103int 104inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx, 105 int plusy) 106{ 107 int padlen, optlen, off; 108 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len; 109 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 110 111 /* argument validation */ 112 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 113 return(-1); 114 if (plusy < 0 || plusy > 7) 115 return(-1); 116 117 /* 118 * If this is the first option, allocate space for the 119 * first 2 bytes(for next header and length fields) of 120 * the option header. 121 */ 122 if (bp == (u_char *)eh) { 123 bp += 2; 124 cmsg->cmsg_len += 2; 125 } 126 127 /* calculate pad length before the option. */ 128 off = bp - (u_char *)eh; 129 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 130 (off % multx); 131 padlen += plusy; 132 padlen %= multx; /* keep the pad as short as possible */ 133 /* insert padding */ 134 inet6_insert_padopt(bp, padlen); 135 cmsg->cmsg_len += padlen; 136 bp += padlen; 137 138 /* copy the option */ 139 if (typep[0] == IP6OPT_PAD1) 140 optlen = 1; 141 else 142 optlen = typep[1] + 2; 143 memcpy(bp, typep, optlen); 144 bp += optlen; 145 cmsg->cmsg_len += optlen; 146 147 /* calculate pad length after the option and insert the padding */ 148 off = bp - (u_char *)eh; 149 padlen = ((off + 7) & ~7) - off; 150 inet6_insert_padopt(bp, padlen); 151 bp += padlen; 152 cmsg->cmsg_len += padlen; 153 154 /* update the length field of the ip6 option header */ 155 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 156 157 return(0); 158} 159 160/* 161 * This function appends a Hop-by-Hop option or a Destination option 162 * into an ancillary data object that has been initialized by 163 * inet6_option_init(). This function returns a pointer to the 8-bit 164 * option type field that starts the option on success, or NULL on an 165 * error. 166 * The difference between this function and inet6_option_append() is 167 * that the latter copies the contents of a previously built option into 168 * the ancillary data object while the current function returns a 169 * pointer to the space in the data object where the option's TLV must 170 * then be built by the caller. 171 * 172 */ 173u_int8_t * 174inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy) 175{ 176 int padlen, off; 177 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len; 178 u_int8_t *retval; 179 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg); 180 181 /* argument validation */ 182 if (multx != 1 && multx != 2 && multx != 4 && multx != 8) 183 return(NULL); 184 if (plusy < 0 || plusy > 7) 185 return(NULL); 186 187 /* 188 * If this is the first option, allocate space for the 189 * first 2 bytes(for next header and length fields) of 190 * the option header. 191 */ 192 if (bp == (u_char *)eh) { 193 bp += 2; 194 cmsg->cmsg_len += 2; 195 } 196 197 /* calculate pad length before the option. */ 198 off = bp - (u_char *)eh; 199 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) - 200 (off % multx); 201 padlen += plusy; 202 padlen %= multx; /* keep the pad as short as possible */ 203 /* insert padding */ 204 inet6_insert_padopt(bp, padlen); 205 cmsg->cmsg_len += padlen; 206 bp += padlen; 207 208 /* keep space to store specified length of data */ 209 retval = bp; 210 bp += datalen; 211 cmsg->cmsg_len += datalen; 212 213 /* calculate pad length after the option and insert the padding */ 214 off = bp - (u_char *)eh; 215 padlen = ((off + 7) & ~7) - off; 216 inet6_insert_padopt(bp, padlen); 217 bp += padlen; 218 cmsg->cmsg_len += padlen; 219 220 /* update the length field of the ip6 option header */ 221 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1; 222 223 return(retval); 224} 225 226/* 227 * This function processes the next Hop-by-Hop option or Destination 228 * option in an ancillary data object. If another option remains to be 229 * processed, the return value of the function is 0 and *tptrp points to 230 * the 8-bit option type field (which is followed by the 8-bit option 231 * data length, followed by the option data). If no more options remain 232 * to be processed, the return value is -1 and *tptrp is NULL. If an 233 * error occurs, the return value is -1 and *tptrp is not NULL. 234 * (RFC 2292, 6.3.5) 235 */ 236int 237inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp) 238{ 239 struct ip6_ext *ip6e; 240 int hdrlen, optlen; 241 u_int8_t *lim; 242 243 if (cmsg->cmsg_level != IPPROTO_IPV6 || 244 (cmsg->cmsg_type != IPV6_HOPOPTS && 245 cmsg->cmsg_type != IPV6_DSTOPTS)) 246 return(-1); 247 248 /* message length validation */ 249 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 250 return(-1); 251 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 252 hdrlen = (ip6e->ip6e_len + 1) << 3; 253 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 254 return(-1); 255 256 /* 257 * If the caller does not specify the starting point, 258 * simply return the 1st option. 259 * Otherwise, search the option list for the next option. 260 */ 261 lim = (u_int8_t *)ip6e + hdrlen; 262 if (*tptrp == NULL) 263 *tptrp = (u_int8_t *)(ip6e + 1); 264 else { 265 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 266 return(-1); 267 268 *tptrp = *tptrp + optlen; 269 } 270 if (*tptrp >= lim) { /* there is no option */ 271 *tptrp = NULL; 272 return(-1); 273 } 274 /* 275 * Finally, checks if the next option is safely stored in the 276 * cmsg data. 277 */ 278 if (ip6optlen(*tptrp, lim) == 0) 279 return(-1); 280 else 281 return(0); 282} 283 284/* 285 * This function is similar to the inet6_option_next() function, 286 * except this function lets the caller specify the option type to be 287 * searched for, instead of always returning the next option in the 288 * ancillary data object. 289 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think 290 * it's a typo. The variable should be type of u_int8_t **. 291 */ 292int 293inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type) 294{ 295 struct ip6_ext *ip6e; 296 int hdrlen, optlen; 297 u_int8_t *optp, *lim; 298 299 if (cmsg->cmsg_level != IPPROTO_IPV6 || 300 (cmsg->cmsg_type != IPV6_HOPOPTS && 301 cmsg->cmsg_type != IPV6_DSTOPTS)) 302 return(-1); 303 304 /* message length validation */ 305 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext))) 306 return(-1); 307 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg); 308 hdrlen = (ip6e->ip6e_len + 1) << 3; 309 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen)) 310 return(-1); 311 312 /* 313 * If the caller does not specify the starting point, 314 * search from the beginning of the option list. 315 * Otherwise, search from *the next option* of the specified point. 316 */ 317 lim = (u_int8_t *)ip6e + hdrlen; 318 if (*tptrp == NULL) 319 *tptrp = (u_int8_t *)(ip6e + 1); 320 else { 321 if ((optlen = ip6optlen(*tptrp, lim)) == 0) 322 return(-1); 323 324 *tptrp = *tptrp + optlen; 325 } 326 for (optp = *tptrp; optp < lim; optp += optlen) { 327 if (*optp == type) { 328 *tptrp = optp; 329 return(0); 330 } 331 if ((optlen = ip6optlen(optp, lim)) == 0) 332 return(-1); 333 } 334 335 /* search failed */ 336 *tptrp = NULL; 337 return(-1); 338} 339 340/* 341 * Calculate the length of a given IPv6 option. Also checks 342 * if the option is safely stored in user's buffer according to the 343 * calculated length and the limitation of the buffer. 344 */ 345static int 346ip6optlen(u_int8_t *opt, u_int8_t *lim) 347{ 348 int optlen; 349 350 if (*opt == IP6OPT_PAD1) 351 optlen = 1; 352 else { 353 /* is there enough space to store type and len? */ 354 if (opt + 2 > lim) 355 return(0); 356 optlen = *(opt + 1) + 2; 357 } 358 if (opt + optlen <= lim) 359 return(optlen); 360 361 return(0); 362} 363 364static void 365inet6_insert_padopt(u_char *p, int len) 366{ 367 switch(len) { 368 case 0: 369 return; 370 case 1: 371 p[0] = IP6OPT_PAD1; 372 return; 373 default: 374 p[0] = IP6OPT_PADN; 375 p[1] = len - 2; 376 memset(&p[2], 0, len - 2); 377 return; 378 } 379} 380 381/* 382 * The following functions are defined in RFC3542, which is a successor 383 * of RFC2292. 384 */ 385 386int 387inet6_opt_init(void *extbuf, socklen_t extlen) 388{ 389 struct ip6_ext *ext = (struct ip6_ext *)extbuf; 390 391 if (extlen == 0 || (extlen % 8)) { 392 return(-1); 393 } 394 395 if (ext) { 396 ext->ip6e_len = (extlen >> 3) - 1; 397 } 398 399 return(2); /* sizeof the next and the length fields */ 400} 401 402int 403inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type, socklen_t len, u_int8_t align, void **databufp) 404{ 405 int currentlen = offset, padlen = 0; 406 407 /* 408 * The option type must have a value from 2 to 255, inclusive. 409 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.) 410 */ 411 if (type < 2) 412 return(-1); 413 414 /* 415 * The option data length must have a value between 0 and 255, 416 * inclusive, and is the length of the option data that follows. 417 */ 418 if (len > 255) { 419 return(-1); 420 } 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 467int 468inet6_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 492int 493inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen) 494{ 495 memcpy((u_int8_t *)databuf + offset, val, vallen); 496 return(offset + vallen); 497} 498 499int 500inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep, socklen_t *lenp, void **databufp) 501{ 502 u_int8_t *optp, *lim; 503 int optlen; 504 505 /* Validate extlen. XXX: is the variable really necessary?? */ 506 if (extlen == 0 || (extlen % 8)) 507 return(-1); 508 lim = (u_int8_t *)extbuf + extlen; 509 510 /* 511 * If this is the first time this function called for this options 512 * header, simply return the 1st option. 513 * Otherwise, search the option list for the next option. 514 */ 515 if (offset == 0) { 516 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1); 517 } 518 else 519 optp = (u_int8_t *)extbuf + offset; 520 521 /* Find the next option skipping any padding options. */ 522 while(optp < lim) { 523 switch(*optp) { 524 case IP6OPT_PAD1: 525 optp++; 526 break; 527 case IP6OPT_PADN: 528 if ((optlen = ip6optlen(optp, lim)) == 0) 529 goto optend; 530 optp += optlen; 531 break; 532 default: /* found */ 533 if ((optlen = ip6optlen(optp, lim)) == 0) 534 goto optend; 535 *typep = *optp; 536 *lenp = optlen - 2; 537 *databufp = optp + 2; 538 return(optp + optlen - (u_int8_t *)extbuf); 539 } 540 } 541 542 optend: 543 *databufp = NULL; /* for safety */ 544 return(-1); 545} 546 547int 548inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type, socklen_t *lenp, void **databufp) 549{ 550 u_int8_t *optp, *lim; 551 int optlen; 552 553 /* Validate extlen. XXX: is the variable really necessary?? */ 554 if (extlen == 0 || (extlen % 8)) 555 return(-1); 556 lim = (u_int8_t *)extbuf + extlen; 557 558 /* 559 * If this is the first time this function called for this options 560 * header, simply return the 1st option. 561 * Otherwise, search the option list for the next option. 562 */ 563 if (offset == 0) { 564 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1); 565 } 566 else 567 optp = (u_int8_t *)extbuf + offset; 568 569 /* Find the specified option */ 570 while(optp < lim) { 571 if ((optlen = ip6optlen(optp, lim)) == 0) 572 goto optend; 573 574 if (*optp == type) { /* found */ 575 *lenp = optlen - 2; 576 *databufp = optp + 2; 577 return(optp + optlen - (u_int8_t *)extbuf); 578 } 579 580 optp += optlen; 581 } 582 583 optend: 584 *databufp = NULL; /* for safety */ 585 return(-1); 586} 587 588int 589inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen) 590{ 591 /* we can't assume alignment here */ 592 memcpy(val, (u_int8_t *)databuf + offset, vallen); 593 594 return(offset + vallen); 595} 596