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