gen.subproj/ip6opt.c

   1 /*
   2  * Copyright (c) 2018 Apple Inc. All rights reserved.
   3  */
   4 /*      $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $    */
   5
   6 /*
   7  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   8  * All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the project nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.8.10.2.2.1 2010/06/14 02:09:06 kensmith Exp $
  35  */
  36
  37 #include "libinfo_common.h"
  38
  39 /*
  40  * These routines support RFC 3542
  41  * __APPLE_USE_RFC_3542 selects the appropriate API in <netinet6/in6.h>
  42  */
  43 #define __APPLE_USE_RFC_3542
  44
  45 #include <sys/cdefs.h>
  46
  47 #include <sys/param.h>
  48 #include <sys/types.h>
  49 #include <sys/socket.h>
  50
  51 #include <netinet/in.h>
  52 #include <netinet/ip6.h>
  53
  54 #include <string.h>
  55 #include <stdio.h>
  56
  57 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
  58 static void inet6_insert_padopt(u_char *p, int len);
  59
  60 /*
  61  * This function returns the number of bytes required to hold an option
  62  * when it is stored as ancillary data, including the cmsghdr structure
  63  * at the beginning, and any padding at the end (to make its size a
  64  * multiple of 8 bytes).  The argument is the size of the structure
  65  * defining the option, which must include any pad bytes at the
  66  * beginning (the value y in the alignment term "xn + y"), the type
  67  * byte, the length byte, and the option data.
  68  */
  69 LIBINFO_EXPORT
  70 int
  71 inet6_option_space(int nbytes)
  72 {
  73         nbytes += 2;    /* we need space for nxt-hdr and length fields */
  74         return(CMSG_SPACE((nbytes + 7) & ~7));
  75 }
  76
  77 /*
  78  * This function is called once per ancillary data object that will
  79  * contain either Hop-by-Hop or Destination options.  It returns 0 on
  80  * success or -1 on an error.
  81  */
  82 LIBINFO_EXPORT
  83 int
  84 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
  85 {
  86         struct cmsghdr *ch = (struct cmsghdr *)bp;
  87
  88         /* argument validation */
  89         if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
  90                 return(-1);
  91
  92         ch->cmsg_level = IPPROTO_IPV6;
  93         ch->cmsg_type = type;
  94         ch->cmsg_len = CMSG_LEN(0);
  95
  96         *cmsgp = ch;
  97         return(0);
  98 }
  99
 100 /*
 101  * This function appends a Hop-by-Hop option or a Destination option
 102  * into an ancillary data object that has been initialized by
 103  * inet6_option_init().  This function returns 0 if it succeeds or -1 on
 104  * an error.
 105  * multx is the value x in the alignment term "xn + y" described
 106  * earlier.  It must have a value of 1, 2, 4, or 8.
 107  * plusy is the value y in the alignment term "xn + y" described
 108  * earlier.  It must have a value between 0 and 7, inclusive.
 109  */
 110 LIBINFO_EXPORT
 111 int
 112 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
 113     int plusy)
 114 {
 115         int padlen, optlen, off;
 116         u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
 117         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 118
 119         /* argument validation */
 120         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 121                 return(-1);
 122         if (plusy < 0 || plusy > 7)
 123                 return(-1);
 124
 125         /*
 126          * If this is the first option, allocate space for the
 127          * first 2 bytes(for next header and length fields) of
 128          * the option header.
 129          */
 130         if (bp == (u_char *)eh) {
 131                 bp += 2;
 132                 cmsg->cmsg_len += 2;
 133         }
 134
 135         /* calculate pad length before the option. */
 136         off = bp - (u_char *)eh;
 137         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 138                 (off % multx);
 139         padlen += plusy;
 140         padlen %= multx;        /* keep the pad as short as possible */
 141         /* insert padding */
 142         inet6_insert_padopt(bp, padlen);
 143         cmsg->cmsg_len += padlen;
 144         bp += padlen;
 145
 146         /* copy the option */
 147         if (typep[0] == IP6OPT_PAD1)
 148                 optlen = 1;
 149         else
 150                 optlen = typep[1] + 2;
 151         memcpy(bp, typep, optlen);
 152         bp += optlen;
 153         cmsg->cmsg_len += optlen;
 154
 155         /* calculate pad length after the option and insert the padding */
 156         off = bp - (u_char *)eh;
 157         padlen = ((off + 7) & ~7) - off;
 158         inet6_insert_padopt(bp, padlen);
 159         bp += padlen;
 160         cmsg->cmsg_len += padlen;
 161
 162         /* update the length field of the ip6 option header */
 163         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 164
 165         return(0);
 166 }
 167
 168 /*
 169  * This function appends a Hop-by-Hop option or a Destination option
 170  * into an ancillary data object that has been initialized by
 171  * inet6_option_init().  This function returns a pointer to the 8-bit
 172  * option type field that starts the option on success, or NULL on an
 173  * error.
 174  * The difference between this function and inet6_option_append() is
 175  * that the latter copies the contents of a previously built option into
 176  * the ancillary data object while the current function returns a
 177  * pointer to the space in the data object where the option's TLV must
 178  * then be built by the caller.
 179  *
 180  */
 181 LIBINFO_EXPORT
 182 u_int8_t *
 183 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
 184 {
 185         int padlen, off;
 186         u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
 187         u_int8_t *retval;
 188         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 189
 190         /* argument validation */
 191         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 192                 return(NULL);
 193         if (plusy < 0 || plusy > 7)
 194                 return(NULL);
 195
 196         /*
 197          * If this is the first option, allocate space for the
 198          * first 2 bytes(for next header and length fields) of
 199          * the option header.
 200          */
 201         if (bp == (u_char *)eh) {
 202                 bp += 2;
 203                 cmsg->cmsg_len += 2;
 204         }
 205
 206         /* calculate pad length before the option. */
 207         off = bp - (u_char *)eh;
 208         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 209                 (off % multx);
 210         padlen += plusy;
 211         padlen %= multx;        /* keep the pad as short as possible */
 212         /* insert padding */
 213         inet6_insert_padopt(bp, padlen);
 214         cmsg->cmsg_len += padlen;
 215         bp += padlen;
 216
 217         /* keep space to store specified length of data */
 218         retval = bp;
 219         bp += datalen;
 220         cmsg->cmsg_len += datalen;
 221
 222         /* calculate pad length after the option and insert the padding */
 223         off = bp - (u_char *)eh;
 224         padlen = ((off + 7) & ~7) - off;
 225         inet6_insert_padopt(bp, padlen);
 226         bp += padlen;
 227         cmsg->cmsg_len += padlen;
 228
 229         /* update the length field of the ip6 option header */
 230         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 231
 232         return(retval);
 233 }
 234
 235 /*
 236  * This function processes the next Hop-by-Hop option or Destination
 237  * option in an ancillary data object.  If another option remains to be
 238  * processed, the return value of the function is 0 and *tptrp points to
 239  * the 8-bit option type field (which is followed by the 8-bit option
 240  * data length, followed by the option data).  If no more options remain
 241  * to be processed, the return value is -1 and *tptrp is NULL.  If an
 242  * error occurs, the return value is -1 and *tptrp is not NULL.
 243  * (RFC 2292, 6.3.5)
 244  */
 245 LIBINFO_EXPORT
 246 int
 247 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
 248 {
 249         struct ip6_ext *ip6e;
 250         int hdrlen, optlen;
 251         u_int8_t *lim;
 252
 253         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 254             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 255              cmsg->cmsg_type != IPV6_DSTOPTS))
 256                 return(-1);
 257
 258         /* message length validation */
 259         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 260                 return(-1);
 261         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 262         hdrlen = (ip6e->ip6e_len + 1) << 3;
 263         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 264                 return(-1);
 265
 266         /*
 267          * If the caller does not specify the starting point,
 268          * simply return the 1st option.
 269          * Otherwise, search the option list for the next option.
 270          */
 271         lim = (u_int8_t *)ip6e + hdrlen;
 272         if (*tptrp == NULL)
 273                 *tptrp = (u_int8_t *)(ip6e + 1);
 274         else {
 275                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 276                         return(-1);
 277
 278                 *tptrp = *tptrp + optlen;
 279         }
 280         if (*tptrp >= lim) {    /* there is no option */
 281                 *tptrp = NULL;
 282                 return(-1);
 283         }
 284         /*
 285          * Finally, checks if the next option is safely stored in the
 286          * cmsg data.
 287          */
 288         if (ip6optlen(*tptrp, lim) == 0)
 289                 return(-1);
 290         else
 291                 return(0);
 292 }
 293
 294 /*
 295  * This function is similar to the inet6_option_next() function,
 296  * except this function lets the caller specify the option type to be
 297  * searched for, instead of always returning the next option in the
 298  * ancillary data object.
 299  * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
 300  *       it's a typo. The variable should be type of u_int8_t **.
 301  */
 302 LIBINFO_EXPORT
 303 int
 304 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
 305 {
 306         struct ip6_ext *ip6e;
 307         int hdrlen, optlen;
 308         u_int8_t *optp, *lim;
 309
 310         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 311             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 312              cmsg->cmsg_type != IPV6_DSTOPTS))
 313                 return(-1);
 314
 315         /* message length validation */
 316         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 317                 return(-1);
 318         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 319         hdrlen = (ip6e->ip6e_len + 1) << 3;
 320         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 321                 return(-1);
 322
 323         /*
 324          * If the caller does not specify the starting point,
 325          * search from the beginning of the option list.
 326          * Otherwise, search from *the next option* of the specified point.
 327          */
 328         lim = (u_int8_t *)ip6e + hdrlen;
 329         if (*tptrp == NULL)
 330                 *tptrp = (u_int8_t *)(ip6e + 1);
 331         else {
 332                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 333                         return(-1);
 334
 335                 *tptrp = *tptrp + optlen;
 336         }
 337         for (optp = *tptrp; optp < lim; optp += optlen) {
 338                 if (*optp == type) {
 339                         *tptrp = optp;
 340                         return(0);
 341                 }
 342                 if ((optlen = ip6optlen(optp, lim)) == 0)
 343                         return(-1);
 344         }
 345
 346         /* search failed */
 347         *tptrp = NULL;
 348         return(-1);
 349 }
 350
 351 /*
 352  * Calculate the length of a given IPv6 option. Also checks
 353  * if the option is safely stored in user's buffer according to the
 354  * calculated length and the limitation of the buffer.
 355  */
 356 static int
 357 ip6optlen(u_int8_t *opt, u_int8_t *lim)
 358 {
 359         int optlen;
 360
 361         if (*opt == IP6OPT_PAD1)
 362                 optlen = 1;
 363         else {
 364                 /* is there enough space to store type and len? */
 365                 if (opt + 2 > lim)
 366                         return(0);
 367                 optlen = *(opt + 1) + 2;
 368         }
 369         if (opt + optlen <= lim)
 370                 return(optlen);
 371
 372         return(0);
 373 }
 374
 375 static void
 376 inet6_insert_padopt(u_char *p, int len)
 377 {
 378         switch(len) {
 379          case 0:
 380                  return;
 381          case 1:
 382                  p[0] = IP6OPT_PAD1;
 383                  return;
 384          default:
 385                  p[0] = IP6OPT_PADN;
 386                  p[1] = len - 2;
 387                  memset(&p[2], 0, len - 2);
 388                  return;
 389         }
 390 }
 391
 392 /*
 393  * The following functions are defined in RFC3542, which is a successor
 394  * of RFC2292.
 395  */
 396
 397 LIBINFO_EXPORT
 398 int
 399 inet6_opt_init(void *extbuf, socklen_t extlen)
 400 {
 401         struct ip6_ext *ext = (struct ip6_ext *)extbuf;
 402
 403         if (extlen == 0 || (extlen % 8)) {
 404                 return(-1);
 405         }
 406
 407         if (ext) {
 408                 ext->ip6e_len = (extlen >> 3) - 1;
 409         }
 410
 411         return(2);              /* sizeof the next and the length fields */
 412 }
 413
 414 LIBINFO_EXPORT
 415 int
 416 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type, socklen_t len, u_int8_t align, void **databufp)
 417 {
 418         int currentlen = offset, padlen = 0;
 419
 420         /*
 421          * The option type must have a value from 2 to 255, inclusive.
 422          * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
 423          */
 424         if (type < 2)
 425                 return(-1);
 426
 427         /*
 428          * The option data length must have a value between 0 and 255,
 429          * inclusive, and is the length of the option data that follows.
 430          */
 431         if (len > 255) {
 432                 return(-1);
 433         }
 434
 435         /*
 436          * The align parameter must have a value of 1, 2, 4, or 8.
 437          * The align value can not exceed the value of len.
 438          */
 439         if (align != 1 && align != 2 && align != 4 && align != 8)
 440                 return(-1);
 441         if (align > len)
 442                 return(-1);
 443
 444         /* Calculate the padding length. */
 445         currentlen += 2 + len;  /* 2 means "type + len" */
 446         if (currentlen % align)
 447                 padlen = align - (currentlen % align);
 448
 449         /* The option must fit in the extension header buffer. */
 450         currentlen += padlen;
 451         if (extlen &&           /* XXX: right? */
 452             currentlen > extlen)
 453                 return(-1);
 454
 455         if (extbuf) {
 456                 u_int8_t *optp = (u_int8_t *)extbuf + offset;
 457
 458                 if (padlen == 1) {
 459                         /* insert a Pad1 option */
 460                         *optp = IP6OPT_PAD1;
 461                         optp++;
 462                 }
 463                 else if (padlen > 0) {
 464                         /* insert a PadN option for alignment */
 465                         *optp++ = IP6OPT_PADN;
 466                         *optp++ = padlen - 2;
 467                         memset(optp, 0, padlen - 2);
 468                         optp += (padlen - 2);
 469                 }
 470
 471                 *optp++ = type;
 472                 *optp++ = len;
 473
 474                 *databufp = optp;
 475         }
 476
 477         return(currentlen);
 478 }
 479
 480 LIBINFO_EXPORT
 481 int
 482 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
 483 {
 484         int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;;
 485
 486         if (extbuf) {
 487                 u_int8_t *padp;
 488                 int padlen = updatelen - offset;
 489
 490                 if (updatelen > extlen)
 491                         return(-1);
 492
 493                 padp = (u_int8_t *)extbuf + offset;
 494                 if (padlen == 1)
 495                         *padp = IP6OPT_PAD1;
 496                 else if (padlen > 0) {
 497                         *padp++ = IP6OPT_PADN;
 498                         *padp++ = (padlen - 2);
 499                         memset(padp, 0, padlen - 2);
 500                 }
 501         }
 502
 503         return(updatelen);
 504 }
 505
 506 LIBINFO_EXPORT
 507 int
 508 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
 509 {
 510         memcpy((u_int8_t *)databuf + offset, val, vallen);
 511         return(offset + vallen);
 512 }
 513
 514 LIBINFO_EXPORT
 515 int
 516 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep, socklen_t *lenp, void **databufp)
 517 {
 518         u_int8_t *optp, *lim;
 519         int optlen;
 520
 521         /* Validate extlen. XXX: is the variable really necessary?? */
 522         if (extlen == 0 || (extlen % 8))
 523                 return(-1);
 524         lim = (u_int8_t *)extbuf + extlen;
 525
 526         /*
 527          * If this is the first time this function called for this options
 528          * header, simply return the 1st option.
 529          * Otherwise, search the option list for the next option.
 530          */
 531         if (offset == 0) {
 532                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
 533         }
 534         else
 535                 optp = (u_int8_t *)extbuf + offset;
 536
 537         /* Find the next option skipping any padding options. */
 538         while(optp < lim) {
 539                 switch(*optp) {
 540                 case IP6OPT_PAD1:
 541                         optp++;
 542                         break;
 543                 case IP6OPT_PADN:
 544                         if ((optlen = ip6optlen(optp, lim)) == 0)
 545                                 goto optend;
 546                         optp += optlen;
 547                         break;
 548                 default:        /* found */
 549                         if ((optlen = ip6optlen(optp, lim)) == 0)
 550                                 goto optend;
 551                         *typep = *optp;
 552                         *lenp = optlen - 2;
 553                         *databufp = optp + 2;
 554                         return(optp + optlen - (u_int8_t *)extbuf);
 555                 }
 556         }
 557
 558   optend:
 559         *databufp = NULL; /* for safety */
 560         return(-1);
 561 }
 562
 563 LIBINFO_EXPORT
 564 int
 565 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type, socklen_t *lenp, void **databufp)
 566 {
 567         u_int8_t *optp, *lim;
 568         int optlen;
 569
 570         /* Validate extlen. XXX: is the variable really necessary?? */
 571         if (extlen == 0 || (extlen % 8))
 572                 return(-1);
 573         lim = (u_int8_t *)extbuf + extlen;
 574
 575         /*
 576          * If this is the first time this function called for this options
 577          * header, simply return the 1st option.
 578          * Otherwise, search the option list for the next option.
 579          */
 580         if (offset == 0) {
 581                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
 582         }
 583         else
 584                 optp = (u_int8_t *)extbuf + offset;
 585
 586         /* Find the specified option */
 587         while(optp < lim) {
 588                 if ((optlen = ip6optlen(optp, lim)) == 0)
 589                         goto optend;
 590
 591                 if (*optp == type) { /* found */
 592                         *lenp = optlen - 2;
 593                         *databufp = optp + 2;
 594                         return(optp + optlen - (u_int8_t *)extbuf);
 595                 }
 596
 597                 optp += optlen;
 598         }
 599
 600   optend:
 601         *databufp = NULL; /* for safety */
 602         return(-1);
 603 }
 604
 605 LIBINFO_EXPORT
 606 int
 607 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
 608 {
 609         /* we can't assume alignment here */
 610         memcpy(val, (u_int8_t *)databuf + offset, vallen);
 611
 612         return(offset + vallen);
 613 }