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.
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32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include <sys/param.h>
36 #include <sys/socket.h>
38 #include <netinet/in.h>
39 #include <netinet/ip6.h>
44 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
45 static void inet6_insert_padopt(u_char *p, int len);
47 #ifndef IPV6_2292HOPOPTS
48 #define IPV6_2292HOPOPTS 22
50 #ifndef IPV6_2292DSTOPTS
51 #define IPV6_2292DSTOPTS 23
54 #define is_ipv6_hopopts(x) \
55 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
56 #define is_ipv6_dstopts(x) \
57 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
60 * This function returns the number of bytes required to hold an option
61 * when it is stored as ancillary data, including the cmsghdr structure
62 * at the beginning, and any padding at the end (to make its size a
63 * multiple of 8 bytes). The argument is the size of the structure
64 * defining the option, which must include any pad bytes at the
65 * beginning (the value y in the alignment term "xn + y"), the type
66 * byte, the length byte, and the option data.
69 inet6_option_space(int nbytes)
71 nbytes += 2; /* we need space for nxt-hdr and length fields */
72 return(CMSG_SPACE((nbytes + 7) & ~7));
76 * This function is called once per ancillary data object that will
77 * contain either Hop-by-Hop or Destination options. It returns 0 on
78 * success or -1 on an error.
81 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
83 struct cmsghdr *ch = (struct cmsghdr *)bp;
85 /* argument validation */
86 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
89 ch->cmsg_level = IPPROTO_IPV6;
91 ch->cmsg_len = CMSG_LEN(0);
98 * This function appends a Hop-by-Hop option or a Destination option
99 * into an ancillary data object that has been initialized by
100 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
102 * multx is the value x in the alignment term "xn + y" described
103 * earlier. It must have a value of 1, 2, 4, or 8.
104 * plusy is the value y in the alignment term "xn + y" described
105 * earlier. It must have a value between 0 and 7, inclusive.
108 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
111 int padlen, optlen, off;
112 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
113 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
115 /* argument validation */
116 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
118 if (plusy < 0 || plusy > 7)
122 * If this is the first option, allocate space for the
123 * first 2 bytes(for next header and length fields) of
126 if (bp == (u_char *)eh) {
131 /* calculate pad length before the option. */
132 off = bp - (u_char *)eh;
133 padlen = roundup2(off % multx, multx) - (off % multx);
135 padlen %= multx; /* keep the pad as short as possible */
137 inet6_insert_padopt(bp, padlen);
138 cmsg->cmsg_len += padlen;
141 /* copy the option */
142 if (typep[0] == IP6OPT_PAD1)
145 optlen = typep[1] + 2;
146 memcpy(bp, typep, optlen);
148 cmsg->cmsg_len += optlen;
150 /* calculate pad length after the option and insert the padding */
151 off = bp - (u_char *)eh;
152 padlen = ((off + 7) & ~7) - off;
153 inet6_insert_padopt(bp, padlen);
155 cmsg->cmsg_len += padlen;
157 /* update the length field of the ip6 option header */
158 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
164 * This function appends a Hop-by-Hop option or a Destination option
165 * into an ancillary data object that has been initialized by
166 * inet6_option_init(). This function returns a pointer to the 8-bit
167 * option type field that starts the option on success, or NULL on an
169 * The difference between this function and inet6_option_append() is
170 * that the latter copies the contents of a previously built option into
171 * the ancillary data object while the current function returns a
172 * pointer to the space in the data object where the option's TLV must
173 * then be built by the caller.
177 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
180 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
182 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
184 /* argument validation */
185 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
187 if (plusy < 0 || plusy > 7)
191 * If this is the first option, allocate space for the
192 * first 2 bytes(for next header and length fields) of
195 if (bp == (u_char *)eh) {
200 /* calculate pad length before the option. */
201 off = bp - (u_char *)eh;
202 padlen = roundup2(off % multx, multx) - (off % multx);
204 padlen %= multx; /* keep the pad as short as possible */
206 inet6_insert_padopt(bp, padlen);
207 cmsg->cmsg_len += padlen;
210 /* keep space to store specified length of data */
213 cmsg->cmsg_len += datalen;
215 /* calculate pad length after the option and insert the padding */
216 off = bp - (u_char *)eh;
217 padlen = ((off + 7) & ~7) - off;
218 inet6_insert_padopt(bp, padlen);
220 cmsg->cmsg_len += padlen;
222 /* update the length field of the ip6 option header */
223 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
229 * This function processes the next Hop-by-Hop option or Destination
230 * option in an ancillary data object. If another option remains to be
231 * processed, the return value of the function is 0 and *tptrp points to
232 * the 8-bit option type field (which is followed by the 8-bit option
233 * data length, followed by the option data). If no more options remain
234 * to be processed, the return value is -1 and *tptrp is NULL. If an
235 * error occurs, the return value is -1 and *tptrp is not NULL.
239 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
241 struct ip6_ext *ip6e;
245 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
246 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
247 !is_ipv6_dstopts(cmsg->cmsg_type)))
250 /* message length validation */
251 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
253 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
254 hdrlen = (ip6e->ip6e_len + 1) << 3;
255 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
259 * If the caller does not specify the starting point,
260 * simply return the 1st option.
261 * Otherwise, search the option list for the next option.
263 lim = (u_int8_t *)ip6e + hdrlen;
265 *tptrp = (u_int8_t *)(ip6e + 1);
267 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
270 *tptrp = *tptrp + optlen;
272 if (*tptrp >= lim) { /* there is no option */
277 * Finally, checks if the next option is safely stored in the
280 if (ip6optlen(*tptrp, lim) == 0)
287 * This function is similar to the inet6_option_next() function,
288 * except this function lets the caller specify the option type to be
289 * searched for, instead of always returning the next option in the
290 * ancillary data object.
291 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
292 * it's a typo. The variable should be type of u_int8_t **.
295 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
297 struct ip6_ext *ip6e;
299 u_int8_t *optp, *lim;
301 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
302 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
303 !is_ipv6_dstopts(cmsg->cmsg_type)))
306 /* message length validation */
307 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
309 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
310 hdrlen = (ip6e->ip6e_len + 1) << 3;
311 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
315 * If the caller does not specify the starting point,
316 * search from the beginning of the option list.
317 * Otherwise, search from *the next option* of the specified point.
319 lim = (u_int8_t *)ip6e + hdrlen;
321 *tptrp = (u_int8_t *)(ip6e + 1);
323 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
326 *tptrp = *tptrp + optlen;
328 for (optp = *tptrp; optp < lim; optp += optlen) {
333 if ((optlen = ip6optlen(optp, lim)) == 0)
343 * Calculate the length of a given IPv6 option. Also checks
344 * if the option is safely stored in user's buffer according to the
345 * calculated length and the limitation of the buffer.
348 ip6optlen(u_int8_t *opt, u_int8_t *lim)
352 if (*opt == IP6OPT_PAD1)
355 /* is there enough space to store type and len? */
358 optlen = *(opt + 1) + 2;
360 if (opt + optlen <= lim)
367 inet6_insert_padopt(u_char *p, int len)
378 memset(&p[2], 0, len - 2);
384 * The following functions are defined in RFC3542, which is a successor
389 inet6_opt_init(void *extbuf, socklen_t extlen)
391 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
394 if (extlen <= 0 || (extlen % 8))
396 ext->ip6e_len = (extlen >> 3) - 1;
399 return(2); /* sizeof the next and the length fields */
403 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
404 socklen_t len, u_int8_t align, void **databufp)
406 int currentlen = offset, padlen = 0;
409 * The option type must have a value from 2 to 255, inclusive.
410 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
416 * The option data length must have a value between 0 and 255,
417 * inclusive, and is the length of the option data that follows.
419 if (len > 255 || len < 0 )
423 * The align parameter must have a value of 1, 2, 4, or 8.
424 * The align value can not exceed the value of len.
426 if (align != 1 && align != 2 && align != 4 && align != 8)
431 /* Calculate the padding length. */
432 currentlen += 2 + len; /* 2 means "type + len" */
433 if (currentlen % align)
434 padlen = align - (currentlen % align);
436 /* The option must fit in the extension header buffer. */
437 currentlen += padlen;
438 if (extlen && /* XXX: right? */
443 u_int8_t *optp = (u_int8_t *)extbuf + offset;
446 /* insert a Pad1 option */
450 else if (padlen > 0) {
451 /* insert a PadN option for alignment */
452 *optp++ = IP6OPT_PADN;
453 *optp++ = padlen - 2;
454 memset(optp, 0, padlen - 2);
455 optp += (padlen - 2);
468 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
470 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
474 int padlen = updatelen - offset;
476 if (updatelen > extlen)
479 padp = (u_int8_t *)extbuf + offset;
482 else if (padlen > 0) {
483 *padp++ = IP6OPT_PADN;
484 *padp++ = (padlen - 2);
485 memset(padp, 0, padlen - 2);
493 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
496 memcpy((u_int8_t *)databuf + offset, val, vallen);
497 return(offset + vallen);
501 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
502 socklen_t *lenp, void **databufp)
504 u_int8_t *optp, *lim;
507 /* Validate extlen. XXX: is the variable really necessary?? */
508 if (extlen == 0 || (extlen % 8))
510 lim = (u_int8_t *)extbuf + extlen;
513 * If this is the first time this function called for this options
514 * header, simply return the 1st option.
515 * Otherwise, search the option list for the next option.
518 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
521 optp = (u_int8_t *)extbuf + offset;
523 /* Find the next option skipping any padding options. */
530 if ((optlen = ip6optlen(optp, lim)) == 0)
535 if ((optlen = ip6optlen(optp, lim)) == 0)
539 *databufp = optp + 2;
540 return(optp + optlen - (u_int8_t *)extbuf);
545 *databufp = NULL; /* for safety */
550 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
551 socklen_t *lenp, void **databufp)
553 u_int8_t *optp, *lim;
556 /* Validate extlen. XXX: is the variable really necessary?? */
557 if (extlen == 0 || (extlen % 8))
559 lim = (u_int8_t *)extbuf + extlen;
562 * If this is the first time this function called for this options
563 * header, simply return the 1st option.
564 * Otherwise, search the option list for the next option.
567 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
570 optp = (u_int8_t *)extbuf + offset;
572 /* Find the specified option */
574 if ((optlen = ip6optlen(optp, lim)) == 0)
577 if (*optp == type) { /* found */
579 *databufp = optp + 2;
580 return(optp + optlen - (u_int8_t *)extbuf);
587 *databufp = NULL; /* for safety */
592 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
595 /* we can't assume alignment here */
596 memcpy(val, (u_int8_t *)databuf + offset, vallen);
598 return(offset + vallen);