lib/libc/net/ip6opt.c

   1 /*
   2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the project nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.1 1999/12/16 18:32:01 shin Exp $
  30  * $DragonFly: src/lib/libc/net/ip6opt.c,v 1.6 2007/05/29 10:58:11 hasso Exp $
  31  */
  32
  33 #include <sys/param.h>
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36
  37 #include <netinet/in.h>
  38 #include <netinet/ip6.h>
  39
  40 #include <string.h>
  41 #include <stdio.h>
  42
  43 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
  44 static void inet6_insert_padopt(u_char *p, int len);
  45
  46 /*
  47  * This function returns the number of bytes required to hold an option
  48  * when it is stored as ancillary data, including the cmsghdr structure
  49  * at the beginning, and any padding at the end (to make its size a
  50  * multiple of 8 bytes).  The argument is the size of the structure
  51  * defining the option, which must include any pad bytes at the
  52  * beginning (the value y in the alignment term "xn + y"), the type
  53  * byte, the length byte, and the option data.
  54  */
  55 int
  56 inet6_option_space(int nbytes)
  57 {
  58         nbytes += 2;    /* we need space for nxt-hdr and length fields */
  59         return(CMSG_SPACE((nbytes + 7) & ~7));
  60 }
  61
  62 /*
  63  * This function is called once per ancillary data object that will
  64  * contain either Hop-by-Hop or Destination options.  It returns 0 on
  65  * success or -1 on an error.
  66  */
  67 int
  68 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
  69 {
  70         struct cmsghdr *ch = (struct cmsghdr *)bp;
  71
  72         /* argument validation */
  73         if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
  74                 return(-1);
  75
  76         ch->cmsg_level = IPPROTO_IPV6;
  77         ch->cmsg_type = type;
  78         ch->cmsg_len = CMSG_LEN(0);
  79
  80         *cmsgp = ch;
  81         return(0);
  82 }
  83
  84 /*
  85  * This function appends a Hop-by-Hop option or a Destination option
  86  * into an ancillary data object that has been initialized by
  87  * inet6_option_init().  This function returns 0 if it succeeds or -1 on
  88  * an error.
  89  * multx is the value x in the alignment term "xn + y" described
  90  * earlier.  It must have a value of 1, 2, 4, or 8.
  91  * plusy is the value y in the alignment term "xn + y" described
  92  * earlier.  It must have a value between 0 and 7, inclusive.
  93  */
  94 int
  95 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
  96                     int plusy)
  97 {
  98         int padlen, optlen, off;
  99         u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
 100         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 101
 102         /* argument validation */
 103         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 104                 return(-1);
 105         if (plusy < 0 || plusy > 7)
 106                 return(-1);
 107
 108         /*
 109          * If this is the first option, allocate space for the
 110          * first 2 bytes(for next header and length fields) of
 111          * the option header.
 112          */
 113         if (bp == (u_char *)eh) {
 114                 bp += 2;
 115                 cmsg->cmsg_len += 2;
 116         }
 117
 118         /* calculate pad length before the option. */
 119         off = bp - (u_char *)eh;
 120         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 121                 (off % multx);
 122         padlen += plusy;
 123         /* insert padding */
 124         inet6_insert_padopt(bp, padlen);
 125         cmsg->cmsg_len += padlen;
 126         bp += padlen;
 127
 128         /* copy the option */
 129         if (typep[0] == IP6OPT_PAD1)
 130                 optlen = 1;
 131         else
 132                 optlen = typep[1] + 2;
 133         memcpy(bp, typep, optlen);
 134         bp += optlen;
 135         cmsg->cmsg_len += optlen;
 136
 137         /* calculate pad length after the option and insert the padding */
 138         off = bp - (u_char *)eh;
 139         padlen = ((off + 7) & ~7) - off;
 140         inet6_insert_padopt(bp, padlen);
 141         bp += padlen;
 142         cmsg->cmsg_len += padlen;
 143
 144         /* update the length field of the ip6 option header */
 145         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 146
 147         return(0);
 148 }
 149
 150 /*
 151  * This function appends a Hop-by-Hop option or a Destination option
 152  * into an ancillary data object that has been initialized by
 153  * inet6_option_init().  This function returns a pointer to the 8-bit
 154  * option type field that starts the option on success, or NULL on an
 155  * error.
 156  * The difference between this function and inet6_option_append() is
 157  * that the latter copies the contents of a previously built option into
 158  * the ancillary data object while the current function returns a
 159  * pointer to the space in the data object where the option's TLV must
 160  * then be built by the caller.
 161  *
 162  */
 163 u_int8_t *
 164 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
 165 {
 166         int padlen, off;
 167         u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
 168         u_int8_t *retval;
 169         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 170
 171         /* argument validation */
 172         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 173                 return(NULL);
 174         if (plusy < 0 || plusy > 7)
 175                 return(NULL);
 176
 177         /*
 178          * If this is the first option, allocate space for the
 179          * first 2 bytes(for next header and length fields) of
 180          * the option header.
 181          */
 182         if (bp == (u_char *)eh) {
 183                 bp += 2;
 184                 cmsg->cmsg_len += 2;
 185         }
 186
 187         /* calculate pad length before the option. */
 188         off = bp - (u_char *)eh;
 189         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 190                 (off % multx);
 191         padlen += plusy;
 192         /* insert padding */
 193         inet6_insert_padopt(bp, padlen);
 194         cmsg->cmsg_len += padlen;
 195         bp += padlen;
 196
 197         /* keep space to store specified length of data */
 198         retval = bp;
 199         bp += datalen;
 200         cmsg->cmsg_len += datalen;
 201
 202         /* calculate pad length after the option and insert the padding */
 203         off = bp - (u_char *)eh;
 204         padlen = ((off + 7) & ~7) - off;
 205         inet6_insert_padopt(bp, padlen);
 206         bp += padlen;
 207         cmsg->cmsg_len += padlen;
 208
 209         /* update the length field of the ip6 option header */
 210         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 211
 212         return(retval);
 213 }
 214
 215 /*
 216  * This function processes the next Hop-by-Hop option or Destination
 217  * option in an ancillary data object.  If another option remains to be
 218  * processed, the return value of the function is 0 and *tptrp points to
 219  * the 8-bit option type field (which is followed by the 8-bit option
 220  * data length, followed by the option data).  If no more options remain
 221  * to be processed, the return value is -1 and *tptrp is NULL.  If an
 222  * error occurs, the return value is -1 and *tptrp is not NULL.
 223  * (RFC 2292, 6.3.5)
 224  */
 225 int
 226 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
 227 {
 228         struct ip6_ext *ip6e;
 229         int hdrlen, optlen;
 230         u_int8_t *lim;
 231
 232         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 233             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 234              cmsg->cmsg_type != IPV6_DSTOPTS))
 235                 return(-1);
 236
 237         /* message length validation */
 238         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 239                 return(-1);
 240         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 241         hdrlen = (ip6e->ip6e_len + 1) << 3;
 242         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 243                 return(-1);
 244
 245         /*
 246          * If the caller does not specify the starting point,
 247          * simply return the 1st option.
 248          * Otherwise, search the option list for the next option.
 249          */
 250         lim = (u_int8_t *)ip6e + hdrlen;
 251         if (*tptrp == NULL)
 252                 *tptrp = (u_int8_t *)(ip6e + 1);
 253         else {
 254                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 255                         return(-1);
 256
 257                 *tptrp = *tptrp + optlen;
 258         }
 259         if (*tptrp >= lim) {    /* there is no option */
 260                 *tptrp = NULL;
 261                 return(-1);
 262         }
 263         /*
 264          * Finally, checks if the next option is safely stored in the
 265          * cmsg data.
 266          */
 267         if (ip6optlen(*tptrp, lim) == 0)
 268                 return(-1);
 269         else
 270                 return(0);
 271 }
 272
 273 /*
 274  * This function is similar to the inet6_option_next() function,
 275  * except this function lets the caller specify the option type to be
 276  * searched for, instead of always returning the next option in the
 277  * ancillary data object.
 278  * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
 279  *       it's a typo. The variable should be type of u_int8_t **.
 280  */
 281 int
 282 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
 283 {
 284         struct ip6_ext *ip6e;
 285         int hdrlen, optlen;
 286         u_int8_t *optp, *lim;
 287
 288         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 289             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 290              cmsg->cmsg_type != IPV6_DSTOPTS))
 291                 return(-1);
 292
 293         /* message length validation */
 294         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 295                 return(-1);
 296         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 297         hdrlen = (ip6e->ip6e_len + 1) << 3;
 298         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 299                 return(-1);
 300
 301         /*
 302          * If the caller does not specify the starting point,
 303          * search from the beginning of the option list.
 304          * Otherwise, search from *the next option* of the specified point.
 305          */
 306         lim = (u_int8_t *)ip6e + hdrlen;
 307         if (*tptrp == NULL)
 308                 *tptrp = (u_int8_t *)(ip6e + 1);
 309         else {
 310                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 311                         return(-1);
 312
 313                 *tptrp = *tptrp + optlen;
 314         }
 315         for (optp = *tptrp; optp < lim; optp += optlen) {
 316                 if (*optp == type) {
 317                         *tptrp = optp;
 318                         return(0);
 319                 }
 320                 if ((optlen = ip6optlen(optp, lim)) == 0)
 321                         return(-1);
 322         }
 323
 324         /* search failed */
 325         *tptrp = NULL;
 326         return(-1);
 327 }
 328
 329 /*
 330  * Calculate the length of a given IPv6 option. Also checks
 331  * if the option is safely stored in user's buffer according to the
 332  * calculated length and the limitation of the buffer.
 333  */
 334 static int
 335 ip6optlen(u_int8_t *opt, u_int8_t *lim)
 336 {
 337         int optlen;
 338
 339         if (*opt == IP6OPT_PAD1)
 340                 optlen = 1;
 341         else {
 342                 /* is there enough space to store type and len? */
 343                 if (opt + 2 > lim)
 344                         return(0);
 345                 optlen = *(opt + 1) + 2;
 346         }
 347         if (opt + optlen <= lim)
 348                 return(optlen);
 349
 350         return(0);
 351 }
 352
 353 static void
 354 inet6_insert_padopt(u_char *p, int len)
 355 {
 356         switch(len) {
 357          case 0:
 358                  return;
 359          case 1:
 360                  p[0] = IP6OPT_PAD1;
 361                  return;
 362          default:
 363                  p[0] = IP6OPT_PADN;
 364                  p[1] = len - 2;
 365                  memset(&p[2], 0, len - 2);
 366                  return;
 367         }
 368 }
 369
 370 /*
 371  * The following functions are defined in RFC3542, which is a successor
 372  * of RFC2292.
 373  */
 374
 375 int
 376 inet6_opt_init(void *extbuf, socklen_t extlen)
 377 {
 378         struct ip6_ext *ext = (struct ip6_ext *)extbuf;
 379
 380         if (extlen < 0 || (extlen % 8))
 381                 return (-1);
 382
 383         if (ext) {
 384                 if (extlen == 0)
 385                         return (-1);
 386                 ext->ip6e_len = (extlen >> 3) - 1;
 387         }
 388
 389         return (2);             /* sizeof the next and the length fields */
 390 }
 391
 392 int
 393 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
 394                  socklen_t len, u_int8_t align, void **databufp)
 395 {
 396         int currentlen = offset, padlen = 0;
 397
 398         /*
 399          * The option type must have a value from 2 to 255, inclusive.
 400          * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
 401          */
 402 #if 0 /* always false */
 403         if (type < 2 || type > 255)
 404 #else
 405         if (type < 2)
 406 #endif
 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 }