1 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */
4 * SPDX-License-Identifier: BSD-3-Clause
6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
37 #include <sys/param.h>
38 #include <sys/socket.h>
40 #include <netinet/in.h>
41 #include <netinet/ip6.h>
46 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
47 static void inet6_insert_padopt(u_char *p, int len);
49 #ifndef IPV6_2292HOPOPTS
50 #define IPV6_2292HOPOPTS 22
52 #ifndef IPV6_2292DSTOPTS
53 #define IPV6_2292DSTOPTS 23
56 #define is_ipv6_hopopts(x) \
57 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
58 #define is_ipv6_dstopts(x) \
59 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
62 * This function returns the number of bytes required to hold an option
63 * when it is stored as ancillary data, including the cmsghdr structure
64 * at the beginning, and any padding at the end (to make its size a
65 * multiple of 8 bytes). The argument is the size of the structure
66 * defining the option, which must include any pad bytes at the
67 * beginning (the value y in the alignment term "xn + y"), the type
68 * byte, the length byte, and the option data.
71 inet6_option_space(int nbytes)
73 nbytes += 2; /* we need space for nxt-hdr and length fields */
74 return(CMSG_SPACE((nbytes + 7) & ~7));
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.
83 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
85 struct cmsghdr *ch = (struct cmsghdr *)bp;
87 /* argument validation */
88 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
91 ch->cmsg_level = IPPROTO_IPV6;
93 ch->cmsg_len = CMSG_LEN(0);
100 * This function appends a Hop-by-Hop option or a Destination option
101 * into an ancillary data object that has been initialized by
102 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
104 * multx is the value x in the alignment term "xn + y" described
105 * earlier. It must have a value of 1, 2, 4, or 8.
106 * plusy is the value y in the alignment term "xn + y" described
107 * earlier. It must have a value between 0 and 7, inclusive.
110 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
113 int padlen, optlen, off;
114 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
115 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
117 /* argument validation */
118 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
120 if (plusy < 0 || plusy > 7)
124 * If this is the first option, allocate space for the
125 * first 2 bytes(for next header and length fields) of
128 if (bp == (u_char *)eh) {
133 /* calculate pad length before the option. */
134 off = bp - (u_char *)eh;
135 padlen = roundup2(off % multx, multx) - (off % multx);
137 padlen %= multx; /* keep the pad as short as possible */
139 inet6_insert_padopt(bp, padlen);
140 cmsg->cmsg_len += padlen;
143 /* copy the option */
144 if (typep[0] == IP6OPT_PAD1)
147 optlen = typep[1] + 2;
148 memcpy(bp, typep, optlen);
150 cmsg->cmsg_len += optlen;
152 /* calculate pad length after the option and insert the padding */
153 off = bp - (u_char *)eh;
154 padlen = ((off + 7) & ~7) - off;
155 inet6_insert_padopt(bp, padlen);
157 cmsg->cmsg_len += padlen;
159 /* update the length field of the ip6 option header */
160 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
166 * This function appends a Hop-by-Hop option or a Destination option
167 * into an ancillary data object that has been initialized by
168 * inet6_option_init(). This function returns a pointer to the 8-bit
169 * option type field that starts the option on success, or NULL on an
171 * The difference between this function and inet6_option_append() is
172 * that the latter copies the contents of a previously built option into
173 * the ancillary data object while the current function returns a
174 * pointer to the space in the data object where the option's TLV must
175 * then be built by the caller.
179 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
182 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
184 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
186 /* argument validation */
187 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
189 if (plusy < 0 || plusy > 7)
193 * If this is the first option, allocate space for the
194 * first 2 bytes(for next header and length fields) of
197 if (bp == (u_char *)eh) {
202 /* calculate pad length before the option. */
203 off = bp - (u_char *)eh;
204 padlen = roundup2(off % multx, multx) - (off % multx);
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(const struct cmsghdr *cmsg, u_int8_t **tptrp)
243 struct ip6_ext *ip6e;
247 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
248 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
249 !is_ipv6_dstopts(cmsg->cmsg_type)))
252 /* message length validation */
253 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
255 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
256 hdrlen = (ip6e->ip6e_len + 1) << 3;
257 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
261 * If the caller does not specify the starting point,
262 * simply return the 1st option.
263 * Otherwise, search the option list for the next option.
265 lim = (u_int8_t *)ip6e + hdrlen;
267 *tptrp = (u_int8_t *)(ip6e + 1);
269 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
272 *tptrp = *tptrp + optlen;
274 if (*tptrp >= lim) { /* there is no option */
279 * Finally, checks if the next option is safely stored in the
282 if (ip6optlen(*tptrp, lim) == 0)
289 * This function is similar to the inet6_option_next() function,
290 * except this function lets the caller specify the option type to be
291 * searched for, instead of always returning the next option in the
292 * ancillary data object.
293 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
294 * it's a typo. The variable should be type of u_int8_t **.
297 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
299 struct ip6_ext *ip6e;
301 u_int8_t *optp, *lim;
303 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
304 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
305 !is_ipv6_dstopts(cmsg->cmsg_type)))
308 /* message length validation */
309 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
311 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
312 hdrlen = (ip6e->ip6e_len + 1) << 3;
313 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
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.
321 lim = (u_int8_t *)ip6e + hdrlen;
323 *tptrp = (u_int8_t *)(ip6e + 1);
325 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
328 *tptrp = *tptrp + optlen;
330 for (optp = *tptrp; optp < lim; optp += optlen) {
335 if ((optlen = ip6optlen(optp, lim)) == 0)
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.
350 ip6optlen(u_int8_t *opt, u_int8_t *lim)
354 if (*opt == IP6OPT_PAD1)
357 /* is there enough space to store type and len? */
360 optlen = *(opt + 1) + 2;
362 if (opt + optlen <= lim)
369 inet6_insert_padopt(u_char *p, int len)
380 memset(&p[2], 0, len - 2);
386 * The following functions are defined in RFC3542, which is a successor
391 inet6_opt_init(void *extbuf, socklen_t extlen)
393 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
396 if (extlen <= 0 || (extlen % 8))
398 ext->ip6e_len = (extlen >> 3) - 1;
401 return(2); /* sizeof the next and the length fields */
405 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
406 socklen_t len, u_int8_t align, void **databufp)
408 int currentlen = offset, padlen = 0;
411 * The option type must have a value from 2 to 255, inclusive.
412 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
418 * The option data length must have a value between 0 and 255,
419 * inclusive, and is the length of the option data that follows.
421 if (len > 255 || len < 0 )
425 * The align parameter must have a value of 1, 2, 4, or 8.
426 * The align value can not exceed the value of len.
428 if (align != 1 && align != 2 && align != 4 && align != 8)
433 /* Calculate the padding length. */
434 currentlen += 2 + len; /* 2 means "type + len" */
435 if (currentlen % align)
436 padlen = align - (currentlen % align);
438 /* The option must fit in the extension header buffer. */
439 currentlen += padlen;
440 if (extlen && /* XXX: right? */
445 u_int8_t *optp = (u_int8_t *)extbuf + offset;
448 /* insert a Pad1 option */
452 else if (padlen > 0) {
453 /* insert a PadN option for alignment */
454 *optp++ = IP6OPT_PADN;
455 *optp++ = padlen - 2;
456 memset(optp, 0, padlen - 2);
457 optp += (padlen - 2);
470 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
472 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
476 int padlen = updatelen - offset;
478 if (updatelen > extlen)
481 padp = (u_int8_t *)extbuf + offset;
484 else if (padlen > 0) {
485 *padp++ = IP6OPT_PADN;
486 *padp++ = (padlen - 2);
487 memset(padp, 0, padlen - 2);
495 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
498 memcpy((u_int8_t *)databuf + offset, val, vallen);
499 return(offset + vallen);
503 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
504 socklen_t *lenp, void **databufp)
506 u_int8_t *optp, *lim;
509 /* Validate extlen. XXX: is the variable really necessary?? */
510 if (extlen == 0 || (extlen % 8))
512 lim = (u_int8_t *)extbuf + extlen;
515 * If this is the first time this function called for this options
516 * header, simply return the 1st option.
517 * Otherwise, search the option list for the next option.
520 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
523 optp = (u_int8_t *)extbuf + offset;
525 /* Find the next option skipping any padding options. */
532 if ((optlen = ip6optlen(optp, lim)) == 0)
537 if ((optlen = ip6optlen(optp, lim)) == 0)
541 *databufp = optp + 2;
542 return(optp + optlen - (u_int8_t *)extbuf);
547 *databufp = NULL; /* for safety */
552 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
553 socklen_t *lenp, void **databufp)
555 u_int8_t *optp, *lim;
558 /* Validate extlen. XXX: is the variable really necessary?? */
559 if (extlen == 0 || (extlen % 8))
561 lim = (u_int8_t *)extbuf + extlen;
564 * If this is the first time this function called for this options
565 * header, simply return the 1st option.
566 * Otherwise, search the option list for the next option.
569 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
572 optp = (u_int8_t *)extbuf + offset;
574 /* Find the specified option */
576 if ((optlen = ip6optlen(optp, lim)) == 0)
579 if (*optp == type) { /* found */
581 *databufp = optp + 2;
582 return(optp + optlen - (u_int8_t *)extbuf);
589 *databufp = NULL; /* for safety */
594 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
597 /* we can't assume alignment here */
598 memcpy(val, (u_int8_t *)databuf + offset, vallen);
600 return(offset + vallen);