lib/libc/net/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 2005/07/19 18:13:58 ume Exp $
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/types.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 /*
  48  * This function returns the number of bytes required to hold an option
  49  * when it is stored as ancillary data, including the cmsghdr structure
  50  * at the beginning, and any padding at the end (to make its size a
  51  * multiple of 8 bytes).  The argument is the size of the structure
  52  * defining the option, which must include any pad bytes at the
  53  * beginning (the value y in the alignment term "xn + y"), the type
  54  * byte, the length byte, and the option data.
  55  */
  56 int
  57 inet6_option_space(int nbytes)
  58 {
  59         nbytes += 2;    /* we need space for nxt-hdr and length fields */
  60         return(CMSG_SPACE((nbytes + 7) & ~7));
  61 }
  62
  63 /*
  64  * This function is called once per ancillary data object that will
  65  * contain either Hop-by-Hop or Destination options.  It returns 0 on
  66  * success or -1 on an error.
  67  */
  68 int
  69 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
  70 {
  71         struct cmsghdr *ch = (struct cmsghdr *)bp;
  72
  73         /* argument validation */
  74         if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
  75                 return(-1);
  76
  77         ch->cmsg_level = IPPROTO_IPV6;
  78         ch->cmsg_type = type;
  79         ch->cmsg_len = CMSG_LEN(0);
  80
  81         *cmsgp = ch;
  82         return(0);
  83 }
  84
  85 /*
  86  * This function appends a Hop-by-Hop option or a Destination option
  87  * into an ancillary data object that has been initialized by
  88  * inet6_option_init().  This function returns 0 if it succeeds or -1 on
  89  * an error.
  90  * multx is the value x in the alignment term "xn + y" described
  91  * earlier.  It must have a value of 1, 2, 4, or 8.
  92  * plusy is the value y in the alignment term "xn + y" described
  93  * earlier.  It must have a value between 0 and 7, inclusive.
  94  */
  95 int
  96 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
  97                     int plusy)
  98 {
  99         int padlen, optlen, off;
 100         u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
 101         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 102
 103         /* argument validation */
 104         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 105                 return(-1);
 106         if (plusy < 0 || plusy > 7)
 107                 return(-1);
 108
 109         /*
 110          * If this is the first option, allocate space for the
 111          * first 2 bytes(for next header and length fields) of
 112          * the option header.
 113          */
 114         if (bp == (u_char *)eh) {
 115                 bp += 2;
 116                 cmsg->cmsg_len += 2;
 117         }
 118
 119         /* calculate pad length before the option. */
 120         off = bp - (u_char *)eh;
 121         padlen = roundup2(off % multx, multx) - (off % multx);
 122         padlen += plusy;
 123         padlen %= multx;        /* keep the pad as short as possible */
 124         /* insert padding */
 125         inet6_insert_padopt(bp, padlen);
 126         cmsg->cmsg_len += padlen;
 127         bp += padlen;
 128
 129         /* copy the option */
 130         if (typep[0] == IP6OPT_PAD1)
 131                 optlen = 1;
 132         else
 133                 optlen = typep[1] + 2;
 134         memcpy(bp, typep, optlen);
 135         bp += optlen;
 136         cmsg->cmsg_len += optlen;
 137
 138         /* calculate pad length after the option and insert the padding */
 139         off = bp - (u_char *)eh;
 140         padlen = ((off + 7) & ~7) - off;
 141         inet6_insert_padopt(bp, padlen);
 142         bp += padlen;
 143         cmsg->cmsg_len += padlen;
 144
 145         /* update the length field of the ip6 option header */
 146         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 147
 148         return(0);
 149 }
 150
 151 /*
 152  * This function appends a Hop-by-Hop option or a Destination option
 153  * into an ancillary data object that has been initialized by
 154  * inet6_option_init().  This function returns a pointer to the 8-bit
 155  * option type field that starts the option on success, or NULL on an
 156  * error.
 157  * The difference between this function and inet6_option_append() is
 158  * that the latter copies the contents of a previously built option into
 159  * the ancillary data object while the current function returns a
 160  * pointer to the space in the data object where the option's TLV must
 161  * then be built by the caller.
 162  *
 163  */
 164 u_int8_t *
 165 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
 166 {
 167         int padlen, off;
 168         u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
 169         u_int8_t *retval;
 170         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 171
 172         /* argument validation */
 173         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 174                 return(NULL);
 175         if (plusy < 0 || plusy > 7)
 176                 return(NULL);
 177
 178         /*
 179          * If this is the first option, allocate space for the
 180          * first 2 bytes(for next header and length fields) of
 181          * the option header.
 182          */
 183         if (bp == (u_char *)eh) {
 184                 bp += 2;
 185                 cmsg->cmsg_len += 2;
 186         }
 187
 188         /* calculate pad length before the option. */
 189         off = bp - (u_char *)eh;
 190         padlen = roundup2(off % multx, multx) - (off % multx);
 191         padlen += plusy;
 192         padlen %= multx;        /* keep the pad as short as possible */
 193         /* insert padding */
 194         inet6_insert_padopt(bp, padlen);
 195         cmsg->cmsg_len += padlen;
 196         bp += padlen;
 197
 198         /* keep space to store specified length of data */
 199         retval = bp;
 200         bp += datalen;
 201         cmsg->cmsg_len += datalen;
 202
 203         /* calculate pad length after the option and insert the padding */
 204         off = bp - (u_char *)eh;
 205         padlen = ((off + 7) & ~7) - off;
 206         inet6_insert_padopt(bp, padlen);
 207         bp += padlen;
 208         cmsg->cmsg_len += padlen;
 209
 210         /* update the length field of the ip6 option header */
 211         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 212
 213         return(retval);
 214 }
 215
 216 /*
 217  * This function processes the next Hop-by-Hop option or Destination
 218  * option in an ancillary data object.  If another option remains to be
 219  * processed, the return value of the function is 0 and *tptrp points to
 220  * the 8-bit option type field (which is followed by the 8-bit option
 221  * data length, followed by the option data).  If no more options remain
 222  * to be processed, the return value is -1 and *tptrp is NULL.  If an
 223  * error occurs, the return value is -1 and *tptrp is not NULL.
 224  * (RFC 2292, 6.3.5)
 225  */
 226 int
 227 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
 228 {
 229         struct ip6_ext *ip6e;
 230         int hdrlen, optlen;
 231         u_int8_t *lim;
 232
 233         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 234             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 235              cmsg->cmsg_type != IPV6_DSTOPTS))
 236                 return(-1);
 237
 238         /* message length validation */
 239         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 240                 return(-1);
 241         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 242         hdrlen = (ip6e->ip6e_len + 1) << 3;
 243         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 244                 return(-1);
 245
 246         /*
 247          * If the caller does not specify the starting point,
 248          * simply return the 1st option.
 249          * Otherwise, search the option list for the next option.
 250          */
 251         lim = (u_int8_t *)ip6e + hdrlen;
 252         if (*tptrp == NULL)
 253                 *tptrp = (u_int8_t *)(ip6e + 1);
 254         else {
 255                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 256                         return(-1);
 257
 258                 *tptrp = *tptrp + optlen;
 259         }
 260         if (*tptrp >= lim) {    /* there is no option */
 261                 *tptrp = NULL;
 262                 return(-1);
 263         }
 264         /*
 265          * Finally, checks if the next option is safely stored in the
 266          * cmsg data.
 267          */
 268         if (ip6optlen(*tptrp, lim) == 0)
 269                 return(-1);
 270         else
 271                 return(0);
 272 }
 273
 274 /*
 275  * This function is similar to the inet6_option_next() function,
 276  * except this function lets the caller specify the option type to be
 277  * searched for, instead of always returning the next option in the
 278  * ancillary data object.
 279  * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
 280  *       it's a typo. The variable should be type of u_int8_t **.
 281  */
 282 int
 283 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
 284 {
 285         struct ip6_ext *ip6e;
 286         int hdrlen, optlen;
 287         u_int8_t *optp, *lim;
 288
 289         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 290             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 291              cmsg->cmsg_type != IPV6_DSTOPTS))
 292                 return(-1);
 293
 294         /* message length validation */
 295         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 296                 return(-1);
 297         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 298         hdrlen = (ip6e->ip6e_len + 1) << 3;
 299         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 300                 return(-1);
 301
 302         /*
 303          * If the caller does not specify the starting point,
 304          * search from the beginning of the option list.
 305          * Otherwise, search from *the next option* of the specified point.
 306          */
 307         lim = (u_int8_t *)ip6e + hdrlen;
 308         if (*tptrp == NULL)
 309                 *tptrp = (u_int8_t *)(ip6e + 1);
 310         else {
 311                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 312                         return(-1);
 313
 314                 *tptrp = *tptrp + optlen;
 315         }
 316         for (optp = *tptrp; optp < lim; optp += optlen) {
 317                 if (*optp == type) {
 318                         *tptrp = optp;
 319                         return(0);
 320                 }
 321                 if ((optlen = ip6optlen(optp, lim)) == 0)
 322                         return(-1);
 323         }
 324
 325         /* search failed */
 326         *tptrp = NULL;
 327         return(-1);
 328 }
 329
 330 /*
 331  * Calculate the length of a given IPv6 option. Also checks
 332  * if the option is safely stored in user's buffer according to the
 333  * calculated length and the limitation of the buffer.
 334  */
 335 static int
 336 ip6optlen(u_int8_t *opt, u_int8_t *lim)
 337 {
 338         int optlen;
 339
 340         if (*opt == IP6OPT_PAD1)
 341                 optlen = 1;
 342         else {
 343                 /* is there enough space to store type and len? */
 344                 if (opt + 2 > lim)
 345                         return(0);
 346                 optlen = *(opt + 1) + 2;
 347         }
 348         if (opt + optlen <= lim)
 349                 return(optlen);
 350
 351         return(0);
 352 }
 353
 354 static void
 355 inet6_insert_padopt(u_char *p, int len)
 356 {
 357         switch(len) {
 358         case 0:
 359                 return;
 360         case 1:
 361                 p[0] = IP6OPT_PAD1;
 362                 return;
 363         default:
 364                 p[0] = IP6OPT_PADN;
 365                 p[1] = len - 2;
 366                 memset(&p[2], 0, len - 2);
 367                 return;
 368         }
 369 }
 370
 371 /*
 372  * The following functions are defined in RFC3542, which is a successor
 373  * of RFC2292.
 374  */
 375
 376 int
 377 inet6_opt_init(void *extbuf, socklen_t extlen)
 378 {
 379         struct ip6_ext *ext = (struct ip6_ext *)extbuf;
 380
 381         if (ext) {
 382                 if (extlen <= 0 || (extlen % 8))
 383                         return(-1);
 384                 ext->ip6e_len = (extlen >> 3) - 1;
 385         }
 386
 387         return(2);              /* sizeof the next and the length fields */
 388 }
 389
 390 int
 391 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
 392                  socklen_t len, u_int8_t align, void **databufp)
 393 {
 394         int currentlen = offset, padlen = 0;
 395
 396         /*
 397          * The option type must have a value from 2 to 255, inclusive.
 398          * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
 399          */
 400         if (type < 2)
 401                 return(-1);
 402
 403         /*
 404          * The option data length must have a value between 0 and 255,
 405          * inclusive, and is the length of the option data that follows.
 406          */
 407         if (len > 255)
 408                 return(-1);
 409
 410         /*
 411          * The align parameter must have a value of 1, 2, 4, or 8.
 412          * The align value can not exceed the value of len.
 413          */
 414         if (align != 1 && align != 2 && align != 4 && align != 8)
 415                 return(-1);
 416         if (align > len)
 417                 return(-1);
 418
 419         /* Calculate the padding length. */
 420         currentlen += 2 + len;  /* 2 means "type + len" */
 421         if (currentlen % align)
 422                 padlen = align - (currentlen % align);
 423
 424         /* The option must fit in the extension header buffer. */
 425         currentlen += padlen;
 426         if (extlen &&           /* XXX: right? */
 427             currentlen > extlen)
 428                 return(-1);
 429
 430         if (extbuf) {
 431                 u_int8_t *optp = (u_int8_t *)extbuf + offset;
 432
 433                 if (padlen == 1) {
 434                         /* insert a Pad1 option */
 435                         *optp = IP6OPT_PAD1;
 436                         optp++;
 437                 } else if (padlen > 0) {
 438                         /* insert a PadN option for alignment */
 439                         *optp++ = IP6OPT_PADN;
 440                         *optp++ = padlen - 2;
 441                         memset(optp, 0, padlen - 2);
 442                         optp += (padlen - 2);
 443                 }
 444
 445                 *optp++ = type;
 446                 *optp++ = len;
 447
 448                 *databufp = optp;
 449         }
 450
 451         return(currentlen);
 452 }
 453
 454 int
 455 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
 456 {
 457         int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
 458
 459         if (extbuf) {
 460                 u_int8_t *padp;
 461                 int padlen = updatelen - offset;
 462
 463                 if (updatelen > extlen)
 464                         return(-1);
 465
 466                 padp = (u_int8_t *)extbuf + offset;
 467                 if (padlen == 1)
 468                         *padp = IP6OPT_PAD1;
 469                 else if (padlen > 0) {
 470                         *padp++ = IP6OPT_PADN;
 471                         *padp++ = (padlen - 2);
 472                         memset(padp, 0, padlen - 2);
 473                 }
 474         }
 475
 476         return(updatelen);
 477 }
 478
 479 int
 480 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
 481 {
 482
 483         memcpy((u_int8_t *)databuf + offset, val, vallen);
 484         return(offset + vallen);
 485 }
 486
 487 int
 488 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
 489                socklen_t *lenp, void **databufp)
 490 {
 491         u_int8_t *optp, *lim;
 492         int optlen;
 493
 494         /* Validate extlen. XXX: is the variable really necessary?? */
 495         if (extlen == 0 || (extlen % 8))
 496                 return(-1);
 497         lim = (u_int8_t *)extbuf + extlen;
 498
 499         /*
 500          * If this is the first time this function called for this options
 501          * header, simply return the 1st option.
 502          * Otherwise, search the option list for the next option.
 503          */
 504         if (offset == 0)
 505                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
 506         else
 507                 optp = (u_int8_t *)extbuf + offset;
 508
 509         /* Find the next option skipping any padding options. */
 510         while (optp < lim) {
 511                 switch (*optp) {
 512                 case IP6OPT_PAD1:
 513                         optp++;
 514                         break;
 515                 case IP6OPT_PADN:
 516                         if ((optlen = ip6optlen(optp, lim)) == 0)
 517                                 goto optend;
 518                         optp += optlen;
 519                         break;
 520                 default:        /* found */
 521                         if ((optlen = ip6optlen(optp, lim)) == 0)
 522                                 goto optend;
 523                         *typep = *optp;
 524                         *lenp = optlen - 2;
 525                         *databufp = optp + 2;
 526                         return(optp + optlen - (u_int8_t *)extbuf);
 527                 }
 528         }
 529
 530   optend:
 531         *databufp = NULL; /* for safety */
 532         return(-1);
 533 }
 534
 535 int
 536 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
 537                socklen_t *lenp, void **databufp)
 538 {
 539         u_int8_t *optp, *lim;
 540         int optlen;
 541
 542         /* Validate extlen. XXX: is the variable really necessary?? */
 543         if (extlen == 0 || (extlen % 8))
 544                 return(-1);
 545         lim = (u_int8_t *)extbuf + extlen;
 546
 547         /*
 548          * If this is the first time this function called for this options
 549          * header, simply return the 1st option.
 550          * Otherwise, search the option list for the next option.
 551          */
 552         if (offset == 0)
 553                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
 554         else
 555                 optp = (u_int8_t *)extbuf + offset;
 556
 557         /* Find the specified option */
 558         while (optp < lim) {
 559                 if ((optlen = ip6optlen(optp, lim)) == 0)
 560                         goto optend;
 561
 562                 if (*optp == type) { /* found */
 563                         *lenp = optlen - 2;
 564                         *databufp = optp + 2;
 565                         return(optp + optlen - (u_int8_t *)extbuf);
 566                 }
 567
 568                 optp += optlen;
 569         }
 570
 571   optend:
 572         *databufp = NULL; /* for safety */
 573         return(-1);
 574 }
 575
 576 int
 577 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
 578 {
 579
 580         /* we can't assume alignment here */
 581         memcpy(val, (u_int8_t *)databuf + offset, vallen);
 582
 583         return(offset + vallen);
 584 }