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  * $DragonFly: src/lib/libc/net/ip6opt.c,v 1.6 2007/05/29 10:58:11 hasso Exp $
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/types.h>
  37 #include <sys/socket.h>
  38
  39 #include <netinet/in.h>
  40 #include <netinet/ip6.h>
  41
  42 #include <string.h>
  43 #include <stdio.h>
  44
  45 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
  46 static void inet6_insert_padopt(u_char *p, int len);
  47
  48 /*
  49  * This function returns the number of bytes required to hold an option
  50  * when it is stored as ancillary data, including the cmsghdr structure
  51  * at the beginning, and any padding at the end (to make its size a
  52  * multiple of 8 bytes).  The argument is the size of the structure
  53  * defining the option, which must include any pad bytes at the
  54  * beginning (the value y in the alignment term "xn + y"), the type
  55  * byte, the length byte, and the option data.
  56  */
  57 int
  58 inet6_option_space(int nbytes)
  59 {
  60         nbytes += 2;    /* we need space for nxt-hdr and length fields */
  61         return(CMSG_SPACE((nbytes + 7) & ~7));
  62 }
  63
  64 /*
  65  * This function is called once per ancillary data object that will
  66  * contain either Hop-by-Hop or Destination options.  It returns 0 on
  67  * success or -1 on an error.
  68  */
  69 int
  70 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
  71 {
  72         struct cmsghdr *ch = (struct cmsghdr *)bp;
  73
  74         /* argument validation */
  75         if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
  76                 return(-1);
  77
  78         ch->cmsg_level = IPPROTO_IPV6;
  79         ch->cmsg_type = type;
  80         ch->cmsg_len = CMSG_LEN(0);
  81
  82         *cmsgp = ch;
  83         return(0);
  84 }
  85
  86 /*
  87  * This function appends a Hop-by-Hop option or a Destination option
  88  * into an ancillary data object that has been initialized by
  89  * inet6_option_init().  This function returns 0 if it succeeds or -1 on
  90  * an error.
  91  * multx is the value x in the alignment term "xn + y" described
  92  * earlier.  It must have a value of 1, 2, 4, or 8.
  93  * plusy is the value y in the alignment term "xn + y" described
  94  * earlier.  It must have a value between 0 and 7, inclusive.
  95  */
  96 int
  97 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
  98                     int plusy)
  99 {
 100         int padlen, optlen, off;
 101         u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
 102         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 103
 104         /* argument validation */
 105         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 106                 return(-1);
 107         if (plusy < 0 || plusy > 7)
 108                 return(-1);
 109
 110         /*
 111          * If this is the first option, allocate space for the
 112          * first 2 bytes(for next header and length fields) of
 113          * the option header.
 114          */
 115         if (bp == (u_char *)eh) {
 116                 bp += 2;
 117                 cmsg->cmsg_len += 2;
 118         }
 119
 120         /* calculate pad length before the option. */
 121         off = bp - (u_char *)eh;
 122         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 123                 (off % multx);
 124         padlen += plusy;
 125         padlen %= multx;        /* keep the pad as short as possible */
 126         /* insert padding */
 127         inet6_insert_padopt(bp, padlen);
 128         cmsg->cmsg_len += padlen;
 129         bp += padlen;
 130
 131         /* copy the option */
 132         if (typep[0] == IP6OPT_PAD1)
 133                 optlen = 1;
 134         else
 135                 optlen = typep[1] + 2;
 136         memcpy(bp, typep, optlen);
 137         bp += optlen;
 138         cmsg->cmsg_len += optlen;
 139
 140         /* calculate pad length after the option and insert the padding */
 141         off = bp - (u_char *)eh;
 142         padlen = ((off + 7) & ~7) - off;
 143         inet6_insert_padopt(bp, padlen);
 144         bp += padlen;
 145         cmsg->cmsg_len += padlen;
 146
 147         /* update the length field of the ip6 option header */
 148         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 149
 150         return(0);
 151 }
 152
 153 /*
 154  * This function appends a Hop-by-Hop option or a Destination option
 155  * into an ancillary data object that has been initialized by
 156  * inet6_option_init().  This function returns a pointer to the 8-bit
 157  * option type field that starts the option on success, or NULL on an
 158  * error.
 159  * The difference between this function and inet6_option_append() is
 160  * that the latter copies the contents of a previously built option into
 161  * the ancillary data object while the current function returns a
 162  * pointer to the space in the data object where the option's TLV must
 163  * then be built by the caller.
 164  *
 165  */
 166 u_int8_t *
 167 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
 168 {
 169         int padlen, off;
 170         u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
 171         u_int8_t *retval;
 172         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 173
 174         /* argument validation */
 175         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 176                 return(NULL);
 177         if (plusy < 0 || plusy > 7)
 178                 return(NULL);
 179
 180         /*
 181          * If this is the first option, allocate space for the
 182          * first 2 bytes(for next header and length fields) of
 183          * the option header.
 184          */
 185         if (bp == (u_char *)eh) {
 186                 bp += 2;
 187                 cmsg->cmsg_len += 2;
 188         }
 189
 190         /* calculate pad length before the option. */
 191         off = bp - (u_char *)eh;
 192         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 193                 (off % multx);
 194         padlen += plusy;
 195         padlen %= multx;        /* keep the pad as short as possible */
 196         /* insert padding */
 197         inet6_insert_padopt(bp, padlen);
 198         cmsg->cmsg_len += padlen;
 199         bp += padlen;
 200
 201         /* keep space to store specified length of data */
 202         retval = bp;
 203         bp += datalen;
 204         cmsg->cmsg_len += datalen;
 205
 206         /* calculate pad length after the option and insert the padding */
 207         off = bp - (u_char *)eh;
 208         padlen = ((off + 7) & ~7) - off;
 209         inet6_insert_padopt(bp, padlen);
 210         bp += padlen;
 211         cmsg->cmsg_len += padlen;
 212
 213         /* update the length field of the ip6 option header */
 214         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 215
 216         return(retval);
 217 }
 218
 219 /*
 220  * This function processes the next Hop-by-Hop option or Destination
 221  * option in an ancillary data object.  If another option remains to be
 222  * processed, the return value of the function is 0 and *tptrp points to
 223  * the 8-bit option type field (which is followed by the 8-bit option
 224  * data length, followed by the option data).  If no more options remain
 225  * to be processed, the return value is -1 and *tptrp is NULL.  If an
 226  * error occurs, the return value is -1 and *tptrp is not NULL.
 227  * (RFC 2292, 6.3.5)
 228  */
 229 int
 230 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
 231 {
 232         struct ip6_ext *ip6e;
 233         int hdrlen, optlen;
 234         u_int8_t *lim;
 235
 236         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 237             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 238              cmsg->cmsg_type != IPV6_DSTOPTS))
 239                 return(-1);
 240
 241         /* message length validation */
 242         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 243                 return(-1);
 244         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 245         hdrlen = (ip6e->ip6e_len + 1) << 3;
 246         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 247                 return(-1);
 248
 249         /*
 250          * If the caller does not specify the starting point,
 251          * simply return the 1st option.
 252          * Otherwise, search the option list for the next option.
 253          */
 254         lim = (u_int8_t *)ip6e + hdrlen;
 255         if (*tptrp == NULL)
 256                 *tptrp = (u_int8_t *)(ip6e + 1);
 257         else {
 258                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 259                         return(-1);
 260
 261                 *tptrp = *tptrp + optlen;
 262         }
 263         if (*tptrp >= lim) {    /* there is no option */
 264                 *tptrp = NULL;
 265                 return(-1);
 266         }
 267         /*
 268          * Finally, checks if the next option is safely stored in the
 269          * cmsg data.
 270          */
 271         if (ip6optlen(*tptrp, lim) == 0)
 272                 return(-1);
 273         else
 274                 return(0);
 275 }
 276
 277 /*
 278  * This function is similar to the inet6_option_next() function,
 279  * except this function lets the caller specify the option type to be
 280  * searched for, instead of always returning the next option in the
 281  * ancillary data object.
 282  * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
 283  *       it's a typo. The variable should be type of u_int8_t **.
 284  */
 285 int
 286 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
 287 {
 288         struct ip6_ext *ip6e;
 289         int hdrlen, optlen;
 290         u_int8_t *optp, *lim;
 291
 292         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 293             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 294              cmsg->cmsg_type != IPV6_DSTOPTS))
 295                 return(-1);
 296
 297         /* message length validation */
 298         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 299                 return(-1);
 300         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 301         hdrlen = (ip6e->ip6e_len + 1) << 3;
 302         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 303                 return(-1);
 304
 305         /*
 306          * If the caller does not specify the starting point,
 307          * search from the beginning of the option list.
 308          * Otherwise, search from *the next option* of the specified point.
 309          */
 310         lim = (u_int8_t *)ip6e + hdrlen;
 311         if (*tptrp == NULL)
 312                 *tptrp = (u_int8_t *)(ip6e + 1);
 313         else {
 314                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 315                         return(-1);
 316
 317                 *tptrp = *tptrp + optlen;
 318         }
 319         for (optp = *tptrp; optp < lim; optp += optlen) {
 320                 if (*optp == type) {
 321                         *tptrp = optp;
 322                         return(0);
 323                 }
 324                 if ((optlen = ip6optlen(optp, lim)) == 0)
 325                         return(-1);
 326         }
 327
 328         /* search failed */
 329         *tptrp = NULL;
 330         return(-1);
 331 }
 332
 333 /*
 334  * Calculate the length of a given IPv6 option. Also checks
 335  * if the option is safely stored in user's buffer according to the
 336  * calculated length and the limitation of the buffer.
 337  */
 338 static int
 339 ip6optlen(u_int8_t *opt, u_int8_t *lim)
 340 {
 341         int optlen;
 342
 343         if (*opt == IP6OPT_PAD1)
 344                 optlen = 1;
 345         else {
 346                 /* is there enough space to store type and len? */
 347                 if (opt + 2 > lim)
 348                         return(0);
 349                 optlen = *(opt + 1) + 2;
 350         }
 351         if (opt + optlen <= lim)
 352                 return(optlen);
 353
 354         return(0);
 355 }
 356
 357 static void
 358 inet6_insert_padopt(u_char *p, int len)
 359 {
 360         switch(len) {
 361         case 0:
 362                 return;
 363         case 1:
 364                 p[0] = IP6OPT_PAD1;
 365                 return;
 366         default:
 367                 p[0] = IP6OPT_PADN;
 368                 p[1] = len - 2;
 369                 memset(&p[2], 0, len - 2);
 370                 return;
 371         }
 372 }
 373
 374 /*
 375  * The following functions are defined in RFC3542, which is a successor
 376  * of RFC2292.
 377  */
 378
 379 int
 380 inet6_opt_init(void *extbuf, socklen_t extlen)
 381 {
 382         struct ip6_ext *ext = (struct ip6_ext *)extbuf;
 383
 384         if (extlen < 0 || (extlen % 8))
 385                 return(-1);
 386
 387         if (ext) {
 388                 if (extlen == 0)
 389                         return(-1);
 390                 ext->ip6e_len = (extlen >> 3) - 1;
 391         }
 392
 393         return(2);              /* sizeof the next and the length fields */
 394 }
 395
 396 int
 397 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
 398                  socklen_t len, u_int8_t align, void **databufp)
 399 {
 400         int currentlen = offset, padlen = 0;
 401
 402         /*
 403          * The option type must have a value from 2 to 255, inclusive.
 404          * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
 405          */
 406         if (type < 2)
 407                 return(-1);
 408
 409         /*
 410          * The option data length must have a value between 0 and 255,
 411          * inclusive, and is the length of the option data that follows.
 412          */
 413         if (len < 0 || len > 255)
 414                 return(-1);
 415
 416         /*
 417          * The align parameter must have a value of 1, 2, 4, or 8.
 418          * The align value can not exceed the value of len.
 419          */
 420         if (align != 1 && align != 2 && align != 4 && align != 8)
 421                 return(-1);
 422         if (align > len)
 423                 return(-1);
 424
 425         /* Calculate the padding length. */
 426         currentlen += 2 + len;  /* 2 means "type + len" */
 427         if (currentlen % align)
 428                 padlen = align - (currentlen % align);
 429
 430         /* The option must fit in the extension header buffer. */
 431         currentlen += padlen;
 432         if (extlen &&           /* XXX: right? */
 433             currentlen > extlen)
 434                 return(-1);
 435
 436         if (extbuf) {
 437                 u_int8_t *optp = (u_int8_t *)extbuf + offset;
 438
 439                 if (padlen == 1) {
 440                         /* insert a Pad1 option */
 441                         *optp = IP6OPT_PAD1;
 442                         optp++;
 443                 } else if (padlen > 0) {
 444                         /* insert a PadN option for alignment */
 445                         *optp++ = IP6OPT_PADN;
 446                         *optp++ = padlen - 2;
 447                         memset(optp, 0, padlen - 2);
 448                         optp += (padlen - 2);
 449                 }
 450
 451                 *optp++ = type;
 452                 *optp++ = len;
 453
 454                 *databufp = optp;
 455         }
 456
 457         return(currentlen);
 458 }
 459
 460 int
 461 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
 462 {
 463         int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;;
 464
 465         if (extbuf) {
 466                 u_int8_t *padp;
 467                 int padlen = updatelen - offset;
 468
 469                 if (updatelen > extlen)
 470                         return(-1);
 471
 472                 padp = (u_int8_t *)extbuf + offset;
 473                 if (padlen == 1)
 474                         *padp = IP6OPT_PAD1;
 475                 else if (padlen > 0) {
 476                         *padp++ = IP6OPT_PADN;
 477                         *padp++ = (padlen - 2);
 478                         memset(padp, 0, padlen - 2);
 479                 }
 480         }
 481
 482         return(updatelen);
 483 }
 484
 485 int
 486 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
 487 {
 488
 489         memcpy((u_int8_t *)databuf + offset, val, vallen);
 490         return(offset + vallen);
 491 }
 492
 493 int
 494 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
 495                socklen_t *lenp, void **databufp)
 496 {
 497         u_int8_t *optp, *lim;
 498         int optlen;
 499
 500         /* Validate extlen. XXX: is the variable really necessary?? */
 501         if (extlen == 0 || (extlen % 8))
 502                 return(-1);
 503         lim = (u_int8_t *)extbuf + extlen;
 504
 505         /*
 506          * If this is the first time this function called for this options
 507          * header, simply return the 1st option.
 508          * Otherwise, search the option list for the next option.
 509          */
 510         if (offset == 0)
 511                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
 512         else
 513                 optp = (u_int8_t *)extbuf + offset;
 514
 515         /* Find the next option skipping any padding options. */
 516         while (optp < lim) {
 517                 switch (*optp) {
 518                 case IP6OPT_PAD1:
 519                         optp++;
 520                         break;
 521                 case IP6OPT_PADN:
 522                         if ((optlen = ip6optlen(optp, lim)) == 0)
 523                                 goto optend;
 524                         optp += optlen;
 525                         break;
 526                 default:        /* found */
 527                         if ((optlen = ip6optlen(optp, lim)) == 0)
 528                                 goto optend;
 529                         *typep = *optp;
 530                         *lenp = optlen - 2;
 531                         *databufp = optp + 2;
 532                         return(optp + optlen - (u_int8_t *)extbuf);
 533                 }
 534         }
 535
 536   optend:
 537         *databufp = NULL; /* for safety */
 538         return(-1);
 539 }
 540
 541 int
 542 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
 543                socklen_t *lenp, void **databufp)
 544 {
 545         u_int8_t *optp, *lim;
 546         int optlen;
 547
 548         /* Validate extlen. XXX: is the variable really necessary?? */
 549         if (extlen == 0 || (extlen % 8))
 550                 return(-1);
 551         lim = (u_int8_t *)extbuf + extlen;
 552
 553         /*
 554          * If this is the first time this function called for this options
 555          * header, simply return the 1st option.
 556          * Otherwise, search the option list for the next option.
 557          */
 558         if (offset == 0)
 559                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
 560         else
 561                 optp = (u_int8_t *)extbuf + offset;
 562
 563         /* Find the specified option */
 564         while (optp < lim) {
 565                 if ((optlen = ip6optlen(optp, lim)) == 0)
 566                         goto optend;
 567
 568                 if (*optp == type) { /* found */
 569                         *lenp = optlen - 2;
 570                         *databufp = optp + 2;
 571                         return(optp + optlen - (u_int8_t *)extbuf);
 572                 }
 573
 574                 optp += optlen;
 575         }
 576
 577   optend:
 578         *databufp = NULL; /* for safety */
 579         return(-1);
 580 }
 581
 582 int
 583 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
 584 {
 585
 586         /* we can't assume alignment here */
 587         memcpy(val, (u_int8_t *)databuf + offset, vallen);
 588
 589         return(offset + vallen);
 590 }