gen.subproj/ip6opt.c

   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
  52 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
  53 static 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  */
  64 int
  65 inet6_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  */
  76 int
  77 inet6_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  */
 103 int
 104 inet6_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  */
 173 u_int8_t *
 174 inet6_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  */
 236 int
 237 inet6_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  */
 292 int
 293 inet6_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  */
 345 static int
 346 ip6optlen(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
 364 static void
 365 inet6_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
 386 int
 387 inet6_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
 402 int
 403 inet6_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
 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         memcpy((u_int8_t *)databuf + offset, val, vallen);
 496         return(offset + vallen);
 497 }
 498
 499 int
 500 inet6_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
 547 int
 548 inet6_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
 588 int
 589 inet6_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 }