1 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
36 #include <sys/types.h>
37 #include <sys/socket.h>
39 #include <netinet/in.h>
40 #include <netinet/ip6.h>
45 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
46 static void inet6_insert_padopt(u_char *p, int len);
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.
58 inet6_option_space(nbytes)
61 nbytes += 2; /* we need space for nxt-hdr and length fields */
62 return(CMSG_SPACE((nbytes + 7) & ~7));
66 * This function is called once per ancillary data object that will
67 * contain either Hop-by-Hop or Destination options. It returns 0 on
68 * success or -1 on an error.
71 inet6_option_init(bp, cmsgp, type)
73 struct cmsghdr **cmsgp;
76 struct cmsghdr *ch = (struct cmsghdr *)bp;
78 /* argument validation */
79 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
82 ch->cmsg_level = IPPROTO_IPV6;
84 ch->cmsg_len = CMSG_LEN(0);
91 * This function appends a Hop-by-Hop option or a Destination option
92 * into an ancillary data object that has been initialized by
93 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
95 * multx is the value x in the alignment term "xn + y" described
96 * earlier. It must have a value of 1, 2, 4, or 8.
97 * plusy is the value y in the alignment term "xn + y" described
98 * earlier. It must have a value between 0 and 7, inclusive.
101 inet6_option_append(cmsg, typep, multx, plusy)
102 struct cmsghdr *cmsg;
103 const u_int8_t *typep;
107 int padlen, optlen, off;
108 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
109 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
111 /* argument validation */
112 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
114 if (plusy < 0 || plusy > 7)
118 * If this is the first option, allocate space for the
119 * first 2 bytes(for next header and length fields) of
122 if (bp == (u_char *)eh) {
127 /* calculate pad length before the option. */
128 off = bp - (u_char *)eh;
129 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
132 padlen %= multx; /* keep the pad as short as possible */
134 inet6_insert_padopt(bp, padlen);
135 cmsg->cmsg_len += padlen;
138 /* copy the option */
139 if (typep[0] == IP6OPT_PAD1)
142 optlen = typep[1] + 2;
143 memcpy(bp, typep, optlen);
145 cmsg->cmsg_len += optlen;
147 /* calculate pad length after the option and insert the padding */
148 off = bp - (u_char *)eh;
149 padlen = ((off + 7) & ~7) - off;
150 inet6_insert_padopt(bp, padlen);
152 cmsg->cmsg_len += padlen;
154 /* update the length field of the ip6 option header */
155 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
161 * This function appends a Hop-by-Hop option or a Destination option
162 * into an ancillary data object that has been initialized by
163 * inet6_option_init(). This function returns a pointer to the 8-bit
164 * option type field that starts the option on success, or NULL on an
166 * The difference between this function and inet6_option_append() is
167 * that the latter copies the contents of a previously built option into
168 * the ancillary data object while the current function returns a
169 * pointer to the space in the data object where the option's TLV must
170 * then be built by the caller.
174 inet6_option_alloc(cmsg, datalen, multx, plusy)
175 struct cmsghdr *cmsg;
181 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
183 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
185 /* argument validation */
186 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
188 if (plusy < 0 || plusy > 7)
192 * If this is the first option, allocate space for the
193 * first 2 bytes(for next header and length fields) of
196 if (bp == (u_char *)eh) {
201 /* calculate pad length before the option. */
202 off = bp - (u_char *)eh;
203 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
206 padlen %= multx; /* keep the pad as short as possible */
208 inet6_insert_padopt(bp, padlen);
209 cmsg->cmsg_len += padlen;
212 /* keep space to store specified length of data */
215 cmsg->cmsg_len += datalen;
217 /* calculate pad length after the option and insert the padding */
218 off = bp - (u_char *)eh;
219 padlen = ((off + 7) & ~7) - off;
220 inet6_insert_padopt(bp, padlen);
222 cmsg->cmsg_len += padlen;
224 /* update the length field of the ip6 option header */
225 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
231 * This function processes the next Hop-by-Hop option or Destination
232 * option in an ancillary data object. If another option remains to be
233 * processed, the return value of the function is 0 and *tptrp points to
234 * the 8-bit option type field (which is followed by the 8-bit option
235 * data length, followed by the option data). If no more options remain
236 * to be processed, the return value is -1 and *tptrp is NULL. If an
237 * error occurs, the return value is -1 and *tptrp is not NULL.
241 inet6_option_next(cmsg, tptrp)
242 const struct cmsghdr *cmsg;
245 struct ip6_ext *ip6e;
249 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
250 (cmsg->cmsg_type != IPV6_HOPOPTS &&
251 cmsg->cmsg_type != IPV6_DSTOPTS))
254 /* message length validation */
255 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
257 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
258 hdrlen = (ip6e->ip6e_len + 1) << 3;
259 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
263 * If the caller does not specify the starting point,
264 * simply return the 1st option.
265 * Otherwise, search the option list for the next option.
267 lim = (u_int8_t *)ip6e + hdrlen;
269 *tptrp = (u_int8_t *)(ip6e + 1);
271 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
274 *tptrp = *tptrp + optlen;
276 if (*tptrp >= lim) { /* there is no option */
281 * Finally, checks if the next option is safely stored in the
284 if (ip6optlen(*tptrp, lim) == 0)
291 * This function is similar to the inet6_option_next() function,
292 * except this function lets the caller specify the option type to be
293 * searched for, instead of always returning the next option in the
294 * ancillary data object.
295 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
296 * it's a typo. The variable should be type of u_int8_t **.
299 inet6_option_find(cmsg, tptrp, type)
300 const struct cmsghdr *cmsg;
304 struct ip6_ext *ip6e;
306 u_int8_t *optp, *lim;
308 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
309 (cmsg->cmsg_type != IPV6_HOPOPTS &&
310 cmsg->cmsg_type != IPV6_DSTOPTS))
313 /* message length validation */
314 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
316 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
317 hdrlen = (ip6e->ip6e_len + 1) << 3;
318 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
322 * If the caller does not specify the starting point,
323 * search from the beginning of the option list.
324 * Otherwise, search from *the next option* of the specified point.
326 lim = (u_int8_t *)ip6e + hdrlen;
328 *tptrp = (u_int8_t *)(ip6e + 1);
330 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
333 *tptrp = *tptrp + optlen;
335 for (optp = *tptrp; optp < lim; optp += optlen) {
340 if ((optlen = ip6optlen(optp, lim)) == 0)
350 * Calculate the length of a given IPv6 option. Also checks
351 * if the option is safely stored in user's buffer according to the
352 * calculated length and the limitation of the buffer.
360 if (*opt == IP6OPT_PAD1)
363 /* is there enough space to store type and len? */
366 optlen = *(opt + 1) + 2;
368 if (opt + optlen <= lim)
375 inet6_insert_padopt(u_char *p, int len)
386 memset(&p[2], 0, len - 2);
392 * The following functions are defined in RFC3542, which is a successor
397 inet6_opt_init(void *extbuf, socklen_t extlen)
399 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
401 if (extlen < 0 || (extlen % 8))
407 ext->ip6e_len = (extlen >> 3) - 1;
410 return(2); /* sizeof the next and the length fields */
414 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
415 socklen_t len, u_int8_t align, void **databufp)
417 int currentlen = offset, padlen = 0;
420 * The option type must have a value from 2 to 255, inclusive.
421 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
427 * The option data length must have a value between 0 and 255,
428 * inclusive, and is the length of the option data that follows.
430 if (len < 0 || len > 255)
434 * The align parameter must have a value of 1, 2, 4, or 8.
435 * The align value can not exceed the value of len.
437 if (align != 1 && align != 2 && align != 4 && align != 8)
442 /* Calculate the padding length. */
443 currentlen += 2 + len; /* 2 means "type + len" */
444 if (currentlen % align)
445 padlen = align - (currentlen % align);
447 /* The option must fit in the extension header buffer. */
448 currentlen += padlen;
449 if (extlen && /* XXX: right? */
454 u_int8_t *optp = (u_int8_t *)extbuf + offset;
457 /* insert a Pad1 option */
461 else if (padlen > 0) {
462 /* insert a PadN option for alignment */
463 *optp++ = IP6OPT_PADN;
464 *optp++ = padlen - 2;
465 memset(optp, 0, padlen - 2);
466 optp += (padlen - 2);
479 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
481 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;;
485 int padlen = updatelen - offset;
487 if (updatelen > extlen)
490 padp = (u_int8_t *)extbuf + offset;
493 else if (padlen > 0) {
494 *padp++ = IP6OPT_PADN;
495 *padp++ = (padlen - 2);
496 memset(padp, 0, padlen - 2);
504 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
507 memcpy((u_int8_t *)databuf + offset, val, vallen);
508 return(offset + vallen);
512 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
513 socklen_t *lenp, void **databufp)
515 u_int8_t *optp, *lim;
518 /* Validate extlen. XXX: is the variable really necessary?? */
519 if (extlen == 0 || (extlen % 8))
521 lim = (u_int8_t *)extbuf + extlen;
524 * If this is the first time this function called for this options
525 * header, simply return the 1st option.
526 * Otherwise, search the option list for the next option.
529 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
532 optp = (u_int8_t *)extbuf + offset;
534 /* Find the next option skipping any padding options. */
541 if ((optlen = ip6optlen(optp, lim)) == 0)
546 if ((optlen = ip6optlen(optp, lim)) == 0)
550 *databufp = optp + 2;
551 return(optp + optlen - (u_int8_t *)extbuf);
556 *databufp = NULL; /* for safety */
561 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
562 socklen_t *lenp, void **databufp)
564 u_int8_t *optp, *lim;
567 /* Validate extlen. XXX: is the variable really necessary?? */
568 if (extlen == 0 || (extlen % 8))
570 lim = (u_int8_t *)extbuf + extlen;
573 * If this is the first time this function called for this options
574 * header, simply return the 1st option.
575 * Otherwise, search the option list for the next option.
578 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
581 optp = (u_int8_t *)extbuf + offset;
583 /* Find the specified option */
585 if ((optlen = ip6optlen(optp, lim)) == 0)
588 if (*optp == type) { /* found */
590 *databufp = optp + 2;
591 return(optp + optlen - (u_int8_t *)extbuf);
598 *databufp = NULL; /* for safety */
603 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
606 /* we can't assume alignment here */
607 memcpy(val, (u_int8_t *)databuf + offset, vallen);
609 return(offset + vallen);