gen.subproj/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  */
  31
  32 #include <sys/param.h>
  33 #include <sys/types.h>
  34 #include <sys/socket.h>
  35
  36 #include <netinet/in.h>
  37 #include <netinet/ip6.h>
  38
  39 #include <string.h>
  40 #include <stdio.h>
  41
  42 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
  43 static void inet6_insert_padopt(u_char *p, int len);
  44
  45 /*
  46  * This function returns the number of bytes required to hold an option
  47  * when it is stored as ancillary data, including the cmsghdr structure
  48  * at the beginning, and any padding at the end (to make its size a
  49  * multiple of 8 bytes).  The argument is the size of the structure
  50  * defining the option, which must include any pad bytes at the
  51  * beginning (the value y in the alignment term "xn + y"), the type
  52  * byte, the length byte, and the option data.
  53  */
  54 int
  55 inet6_option_space(nbytes)
  56         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(bp, cmsgp, type)
  69         void *bp;
  70         struct cmsghdr **cmsgp;
  71         int type;
  72 {
  73         register struct cmsghdr *ch = (struct cmsghdr *)bp;
  74
  75         /* argument validation */
  76         if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
  77                 return(-1);
  78
  79         ch->cmsg_level = IPPROTO_IPV6;
  80         ch->cmsg_type = type;
  81         ch->cmsg_len = CMSG_LEN(0);
  82
  83         *cmsgp = ch;
  84         return(0);
  85 }
  86
  87 /*
  88  * This function appends a Hop-by-Hop option or a Destination option
  89  * into an ancillary data object that has been initialized by
  90  * inet6_option_init().  This function returns 0 if it succeeds or -1 on
  91  * an error.
  92  * multx is the value x in the alignment term "xn + y" described
  93  * earlier.  It must have a value of 1, 2, 4, or 8.
  94  * plusy is the value y in the alignment term "xn + y" described
  95  * earlier.  It must have a value between 0 and 7, inclusive.
  96  */
  97 int
  98 inet6_option_append(cmsg, typep, multx, plusy)
  99         struct cmsghdr *cmsg;
 100         const u_int8_t *typep;
 101         int multx;
 102         int plusy;
 103 {
 104         int padlen, optlen, off;
 105         register u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
 106         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 107
 108         /* argument validation */
 109         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 110                 return(-1);
 111         if (plusy < 0 || plusy > 7)
 112                 return(-1);
 113         if (typep[0] > 255)
 114                 return(-1);
 115
 116         /*
 117          * If this is the first option, allocate space for the
 118          * first 2 bytes(for next header and length fields) of
 119          * the option header.
 120          */
 121         if (bp == (u_char *)eh) {
 122                 bp += 2;
 123                 cmsg->cmsg_len += 2;
 124         }
 125
 126         /* calculate pad length before the option. */
 127         off = bp - (u_char *)eh;
 128         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 129                 (off % multx);
 130         padlen += plusy;
 131         /* insert padding */
 132         inet6_insert_padopt(bp, padlen);
 133         cmsg->cmsg_len += padlen;
 134         bp += padlen;
 135
 136         /* copy the option */
 137         if (typep[0] == IP6OPT_PAD1)
 138                 optlen = 1;
 139         else
 140                 optlen = typep[1] + 2;
 141         memcpy(bp, typep, optlen);
 142         bp += optlen;
 143         cmsg->cmsg_len += optlen;
 144
 145         /* calculate pad length after the option and insert the padding */
 146         off = bp - (u_char *)eh;
 147         padlen = ((off + 7) & ~7) - off;
 148         inet6_insert_padopt(bp, padlen);
 149         bp += padlen;
 150         cmsg->cmsg_len += padlen;
 151
 152         /* update the length field of the ip6 option header */
 153         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 154
 155         return(0);
 156 }
 157
 158 /*
 159  * This function appends a Hop-by-Hop option or a Destination option
 160  * into an ancillary data object that has been initialized by
 161  * inet6_option_init().  This function returns a pointer to the 8-bit
 162  * option type field that starts the option on success, or NULL on an
 163  * error.
 164  * The difference between this function and inet6_option_append() is
 165  * that the latter copies the contents of a previously built option into
 166  * the ancillary data object while the current function returns a
 167  * pointer to the space in the data object where the option's TLV must
 168  * then be built by the caller.
 169  *
 170  */
 171 u_int8_t *
 172 inet6_option_alloc(cmsg, datalen, multx, plusy)
 173         struct cmsghdr *cmsg;
 174         int datalen;
 175         int multx;
 176         int plusy;
 177 {
 178         int padlen, off;
 179         register u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
 180         u_int8_t *retval;
 181         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
 182
 183         /* argument validation */
 184         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
 185                 return(NULL);
 186         if (plusy < 0 || plusy > 7)
 187                 return(NULL);
 188
 189         /*
 190          * If this is the first option, allocate space for the
 191          * first 2 bytes(for next header and length fields) of
 192          * the option header.
 193          */
 194         if (bp == (u_char *)eh) {
 195                 bp += 2;
 196                 cmsg->cmsg_len += 2;
 197         }
 198
 199         /* calculate pad length before the option. */
 200         off = bp - (u_char *)eh;
 201         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
 202                 (off % multx);
 203         padlen += plusy;
 204         /* insert padding */
 205         inet6_insert_padopt(bp, padlen);
 206         cmsg->cmsg_len += padlen;
 207         bp += padlen;
 208
 209         /* keep space to store specified length of data */
 210         retval = bp;
 211         bp += datalen;
 212         cmsg->cmsg_len += datalen;
 213
 214         /* calculate pad length after the option and insert the padding */
 215         off = bp - (u_char *)eh;
 216         padlen = ((off + 7) & ~7) - off;
 217         inet6_insert_padopt(bp, padlen);
 218         bp += padlen;
 219         cmsg->cmsg_len += padlen;
 220
 221         /* update the length field of the ip6 option header */
 222         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
 223
 224         return(retval);
 225 }
 226
 227 /*
 228  * This function processes the next Hop-by-Hop option or Destination
 229  * option in an ancillary data object.  If another option remains to be
 230  * processed, the return value of the function is 0 and *tptrp points to
 231  * the 8-bit option type field (which is followed by the 8-bit option
 232  * data length, followed by the option data).  If no more options remain
 233  * to be processed, the return value is -1 and *tptrp is NULL.  If an
 234  * error occurs, the return value is -1 and *tptrp is not NULL.
 235  * (RFC 2292, 6.3.5)
 236  */
 237 int
 238 inet6_option_next(cmsg, tptrp)
 239         const struct cmsghdr *cmsg;
 240         u_int8_t **tptrp;
 241 {
 242         struct ip6_ext *ip6e;
 243         int hdrlen, optlen;
 244         u_int8_t *lim;
 245
 246         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 247             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 248              cmsg->cmsg_type != IPV6_DSTOPTS))
 249                 return(-1);
 250
 251         /* message length validation */
 252         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 253                 return(-1);
 254         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 255         hdrlen = (ip6e->ip6e_len + 1) << 3;
 256         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 257                 return(-1);
 258
 259         /*
 260          * If the caller does not specify the starting point,
 261          * simply return the 1st option.
 262          * Otherwise, search the option list for the next option.
 263          */
 264         lim = (u_int8_t *)ip6e + hdrlen;
 265         if (*tptrp == NULL)
 266                 *tptrp = (u_int8_t *)(ip6e + 1);
 267         else {
 268                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 269                         return(-1);
 270
 271                 *tptrp = *tptrp + optlen;
 272         }
 273         if (*tptrp >= lim) {    /* there is no option */
 274                 *tptrp = NULL;
 275                 return(-1);
 276         }
 277         /*
 278          * Finally, checks if the next option is safely stored in the
 279          * cmsg data.
 280          */
 281         if (ip6optlen(*tptrp, lim) == 0)
 282                 return(-1);
 283         else
 284                 return(0);
 285 }
 286
 287 /*
 288  * This function is similar to the inet6_option_next() function,
 289  * except this function lets the caller specify the option type to be
 290  * searched for, instead of always returning the next option in the
 291  * ancillary data object.
 292  * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
 293  *       it's a typo. The variable should be type of u_int8_t **.
 294  */
 295 int
 296 inet6_option_find(cmsg, tptrp, type)
 297         const struct cmsghdr *cmsg;
 298         u_int8_t **tptrp;
 299         int type;
 300 {
 301         struct ip6_ext *ip6e;
 302         int hdrlen, optlen;
 303         u_int8_t *optp, *lim;
 304
 305         if (cmsg->cmsg_level != IPPROTO_IPV6 ||
 306             (cmsg->cmsg_type != IPV6_HOPOPTS &&
 307              cmsg->cmsg_type != IPV6_DSTOPTS))
 308                 return(-1);
 309
 310         /* message length validation */
 311         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
 312                 return(-1);
 313         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
 314         hdrlen = (ip6e->ip6e_len + 1) << 3;
 315         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
 316                 return(-1);
 317
 318         /*
 319          * If the caller does not specify the starting point,
 320          * search from the beginning of the option list.
 321          * Otherwise, search from *the next option* of the specified point.
 322          */
 323         lim = (u_int8_t *)ip6e + hdrlen;
 324         if (*tptrp == NULL)
 325                 *tptrp = (u_int8_t *)(ip6e + 1);
 326         else {
 327                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
 328                         return(-1);
 329
 330                 *tptrp = *tptrp + optlen;
 331         }
 332         for (optp = *tptrp; optp < lim; optp += optlen) {
 333                 if (*optp == type) {
 334                         *tptrp = optp;
 335                         return(0);
 336                 }
 337                 if ((optlen = ip6optlen(optp, lim)) == 0)
 338                         return(-1);
 339         }
 340
 341         /* search failed */
 342         *tptrp = NULL;
 343         return(-1);
 344 }
 345
 346 /*
 347  * Calculate the length of a given IPv6 option. Also checks
 348  * if the option is safely stored in user's buffer according to the
 349  * calculated length and the limitation of the buffer.
 350  */
 351 static int
 352 ip6optlen(opt, lim)
 353         u_int8_t *opt, *lim;
 354 {
 355         int optlen;
 356
 357         if (*opt == IP6OPT_PAD1)
 358                 optlen = 1;
 359         else {
 360                 /* is there enough space to store type and len? */
 361                 if (opt + 2 > lim)
 362                         return(0);
 363                 optlen = *(opt + 1) + 2;
 364         }
 365         if (opt + optlen <= lim)
 366                 return(optlen);
 367
 368         return(0);
 369 }
 370
 371 static void
 372 inet6_insert_padopt(u_char *p, int len)
 373 {
 374         switch(len) {
 375          case 0:
 376                  return;
 377          case 1:
 378                  p[0] = IP6OPT_PAD1;
 379                  return;
 380          default:
 381                  p[0] = IP6OPT_PADN;
 382                  p[1] = len - 2;
 383                  memset(&p[2], 0, len - 2);
 384                  return;
 385         }
 386 }