1 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */
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31 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.8 2005/07/19 18:13:58 ume Exp $
34 #include <sys/param.h>
35 #include <sys/types.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);
48 * This function returns the number of bytes required to hold an option
49 * when it is stored as ancillary data, including the cmsghdr structure
50 * at the beginning, and any padding at the end (to make its size a
51 * multiple of 8 bytes). The argument is the size of the structure
52 * defining the option, which must include any pad bytes at the
53 * beginning (the value y in the alignment term "xn + y"), the type
54 * byte, the length byte, and the option data.
57 inet6_option_space(int nbytes)
59 nbytes += 2; /* we need space for nxt-hdr and length fields */
60 return(CMSG_SPACE((nbytes + 7) & ~7));
64 * This function is called once per ancillary data object that will
65 * contain either Hop-by-Hop or Destination options. It returns 0 on
66 * success or -1 on an error.
69 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
71 struct cmsghdr *ch = (struct cmsghdr *)bp;
73 /* argument validation */
74 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
77 ch->cmsg_level = IPPROTO_IPV6;
79 ch->cmsg_len = CMSG_LEN(0);
86 * This function appends a Hop-by-Hop option or a Destination option
87 * into an ancillary data object that has been initialized by
88 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
90 * multx is the value x in the alignment term "xn + y" described
91 * earlier. It must have a value of 1, 2, 4, or 8.
92 * plusy is the value y in the alignment term "xn + y" described
93 * earlier. It must have a value between 0 and 7, inclusive.
96 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
99 int padlen, optlen, off;
100 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
101 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
103 /* argument validation */
104 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
106 if (plusy < 0 || plusy > 7)
110 * If this is the first option, allocate space for the
111 * first 2 bytes(for next header and length fields) of
114 if (bp == (u_char *)eh) {
119 /* calculate pad length before the option. */
120 off = bp - (u_char *)eh;
121 padlen = roundup2(off % multx, multx) - (off % multx);
123 padlen %= multx; /* keep the pad as short as possible */
125 inet6_insert_padopt(bp, padlen);
126 cmsg->cmsg_len += padlen;
129 /* copy the option */
130 if (typep[0] == IP6OPT_PAD1)
133 optlen = typep[1] + 2;
134 memcpy(bp, typep, optlen);
136 cmsg->cmsg_len += optlen;
138 /* calculate pad length after the option and insert the padding */
139 off = bp - (u_char *)eh;
140 padlen = ((off + 7) & ~7) - off;
141 inet6_insert_padopt(bp, padlen);
143 cmsg->cmsg_len += padlen;
145 /* update the length field of the ip6 option header */
146 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
152 * This function appends a Hop-by-Hop option or a Destination option
153 * into an ancillary data object that has been initialized by
154 * inet6_option_init(). This function returns a pointer to the 8-bit
155 * option type field that starts the option on success, or NULL on an
157 * The difference between this function and inet6_option_append() is
158 * that the latter copies the contents of a previously built option into
159 * the ancillary data object while the current function returns a
160 * pointer to the space in the data object where the option's TLV must
161 * then be built by the caller.
165 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
168 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
170 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
172 /* argument validation */
173 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
175 if (plusy < 0 || plusy > 7)
179 * If this is the first option, allocate space for the
180 * first 2 bytes(for next header and length fields) of
183 if (bp == (u_char *)eh) {
188 /* calculate pad length before the option. */
189 off = bp - (u_char *)eh;
190 padlen = roundup2(off % multx, multx) - (off % multx);
192 padlen %= multx; /* keep the pad as short as possible */
194 inet6_insert_padopt(bp, padlen);
195 cmsg->cmsg_len += padlen;
198 /* keep space to store specified length of data */
201 cmsg->cmsg_len += datalen;
203 /* calculate pad length after the option and insert the padding */
204 off = bp - (u_char *)eh;
205 padlen = ((off + 7) & ~7) - off;
206 inet6_insert_padopt(bp, padlen);
208 cmsg->cmsg_len += padlen;
210 /* update the length field of the ip6 option header */
211 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
217 * This function processes the next Hop-by-Hop option or Destination
218 * option in an ancillary data object. If another option remains to be
219 * processed, the return value of the function is 0 and *tptrp points to
220 * the 8-bit option type field (which is followed by the 8-bit option
221 * data length, followed by the option data). If no more options remain
222 * to be processed, the return value is -1 and *tptrp is NULL. If an
223 * error occurs, the return value is -1 and *tptrp is not NULL.
227 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
229 struct ip6_ext *ip6e;
233 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
234 (cmsg->cmsg_type != IPV6_HOPOPTS &&
235 cmsg->cmsg_type != IPV6_DSTOPTS))
238 /* message length validation */
239 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
241 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
242 hdrlen = (ip6e->ip6e_len + 1) << 3;
243 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
247 * If the caller does not specify the starting point,
248 * simply return the 1st option.
249 * Otherwise, search the option list for the next option.
251 lim = (u_int8_t *)ip6e + hdrlen;
253 *tptrp = (u_int8_t *)(ip6e + 1);
255 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
258 *tptrp = *tptrp + optlen;
260 if (*tptrp >= lim) { /* there is no option */
265 * Finally, checks if the next option is safely stored in the
268 if (ip6optlen(*tptrp, lim) == 0)
275 * This function is similar to the inet6_option_next() function,
276 * except this function lets the caller specify the option type to be
277 * searched for, instead of always returning the next option in the
278 * ancillary data object.
279 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
280 * it's a typo. The variable should be type of u_int8_t **.
283 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
285 struct ip6_ext *ip6e;
287 u_int8_t *optp, *lim;
289 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
290 (cmsg->cmsg_type != IPV6_HOPOPTS &&
291 cmsg->cmsg_type != IPV6_DSTOPTS))
294 /* message length validation */
295 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
297 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
298 hdrlen = (ip6e->ip6e_len + 1) << 3;
299 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
303 * If the caller does not specify the starting point,
304 * search from the beginning of the option list.
305 * Otherwise, search from *the next option* of the specified point.
307 lim = (u_int8_t *)ip6e + hdrlen;
309 *tptrp = (u_int8_t *)(ip6e + 1);
311 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
314 *tptrp = *tptrp + optlen;
316 for (optp = *tptrp; optp < lim; optp += optlen) {
321 if ((optlen = ip6optlen(optp, lim)) == 0)
331 * Calculate the length of a given IPv6 option. Also checks
332 * if the option is safely stored in user's buffer according to the
333 * calculated length and the limitation of the buffer.
336 ip6optlen(u_int8_t *opt, u_int8_t *lim)
340 if (*opt == IP6OPT_PAD1)
343 /* is there enough space to store type and len? */
346 optlen = *(opt + 1) + 2;
348 if (opt + optlen <= lim)
355 inet6_insert_padopt(u_char *p, int len)
366 memset(&p[2], 0, len - 2);
372 * The following functions are defined in RFC3542, which is a successor
377 inet6_opt_init(void *extbuf, socklen_t extlen)
379 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
382 if (extlen <= 0 || (extlen % 8))
384 ext->ip6e_len = (extlen >> 3) - 1;
387 return(2); /* sizeof the next and the length fields */
391 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
392 socklen_t len, u_int8_t align, void **databufp)
394 int currentlen = offset, padlen = 0;
397 * The option type must have a value from 2 to 255, inclusive.
398 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
404 * The option data length must have a value between 0 and 255,
405 * inclusive, and is the length of the option data that follows.
411 * The align parameter must have a value of 1, 2, 4, or 8.
412 * The align value can not exceed the value of len.
414 if (align != 1 && align != 2 && align != 4 && align != 8)
419 /* Calculate the padding length. */
420 currentlen += 2 + len; /* 2 means "type + len" */
421 if (currentlen % align)
422 padlen = align - (currentlen % align);
424 /* The option must fit in the extension header buffer. */
425 currentlen += padlen;
426 if (extlen && /* XXX: right? */
431 u_int8_t *optp = (u_int8_t *)extbuf + offset;
434 /* insert a Pad1 option */
437 } else if (padlen > 0) {
438 /* insert a PadN option for alignment */
439 *optp++ = IP6OPT_PADN;
440 *optp++ = padlen - 2;
441 memset(optp, 0, padlen - 2);
442 optp += (padlen - 2);
455 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
457 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
461 int padlen = updatelen - offset;
463 if (updatelen > extlen)
466 padp = (u_int8_t *)extbuf + offset;
469 else if (padlen > 0) {
470 *padp++ = IP6OPT_PADN;
471 *padp++ = (padlen - 2);
472 memset(padp, 0, padlen - 2);
480 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
483 memcpy((u_int8_t *)databuf + offset, val, vallen);
484 return(offset + vallen);
488 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
489 socklen_t *lenp, void **databufp)
491 u_int8_t *optp, *lim;
494 /* Validate extlen. XXX: is the variable really necessary?? */
495 if (extlen == 0 || (extlen % 8))
497 lim = (u_int8_t *)extbuf + extlen;
500 * If this is the first time this function called for this options
501 * header, simply return the 1st option.
502 * Otherwise, search the option list for the next option.
505 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
507 optp = (u_int8_t *)extbuf + offset;
509 /* Find the next option skipping any padding options. */
516 if ((optlen = ip6optlen(optp, lim)) == 0)
521 if ((optlen = ip6optlen(optp, lim)) == 0)
525 *databufp = optp + 2;
526 return(optp + optlen - (u_int8_t *)extbuf);
531 *databufp = NULL; /* for safety */
536 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
537 socklen_t *lenp, void **databufp)
539 u_int8_t *optp, *lim;
542 /* Validate extlen. XXX: is the variable really necessary?? */
543 if (extlen == 0 || (extlen % 8))
545 lim = (u_int8_t *)extbuf + extlen;
548 * If this is the first time this function called for this options
549 * header, simply return the 1st option.
550 * Otherwise, search the option list for the next option.
553 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
555 optp = (u_int8_t *)extbuf + offset;
557 /* Find the specified option */
559 if ((optlen = ip6optlen(optp, lim)) == 0)
562 if (*optp == type) { /* found */
564 *databufp = optp + 2;
565 return(optp + optlen - (u_int8_t *)extbuf);
572 *databufp = NULL; /* for safety */
577 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
580 /* we can't assume alignment here */
581 memcpy(val, (u_int8_t *)databuf + offset, vallen);
583 return(offset + vallen);