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 = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
124 padlen %= multx; /* keep the pad as short as possible */
126 inet6_insert_padopt(bp, padlen);
127 cmsg->cmsg_len += padlen;
130 /* copy the option */
131 if (typep[0] == IP6OPT_PAD1)
134 optlen = typep[1] + 2;
135 memcpy(bp, typep, optlen);
137 cmsg->cmsg_len += optlen;
139 /* calculate pad length after the option and insert the padding */
140 off = bp - (u_char *)eh;
141 padlen = ((off + 7) & ~7) - off;
142 inet6_insert_padopt(bp, padlen);
144 cmsg->cmsg_len += padlen;
146 /* update the length field of the ip6 option header */
147 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
153 * This function appends a Hop-by-Hop option or a Destination option
154 * into an ancillary data object that has been initialized by
155 * inet6_option_init(). This function returns a pointer to the 8-bit
156 * option type field that starts the option on success, or NULL on an
158 * The difference between this function and inet6_option_append() is
159 * that the latter copies the contents of a previously built option into
160 * the ancillary data object while the current function returns a
161 * pointer to the space in the data object where the option's TLV must
162 * then be built by the caller.
166 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
169 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
171 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
173 /* argument validation */
174 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
176 if (plusy < 0 || plusy > 7)
180 * If this is the first option, allocate space for the
181 * first 2 bytes(for next header and length fields) of
184 if (bp == (u_char *)eh) {
189 /* calculate pad length before the option. */
190 off = bp - (u_char *)eh;
191 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
194 padlen %= multx; /* keep the pad as short as possible */
196 inet6_insert_padopt(bp, padlen);
197 cmsg->cmsg_len += padlen;
200 /* keep space to store specified length of data */
203 cmsg->cmsg_len += datalen;
205 /* calculate pad length after the option and insert the padding */
206 off = bp - (u_char *)eh;
207 padlen = ((off + 7) & ~7) - off;
208 inet6_insert_padopt(bp, padlen);
210 cmsg->cmsg_len += padlen;
212 /* update the length field of the ip6 option header */
213 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
219 * This function processes the next Hop-by-Hop option or Destination
220 * option in an ancillary data object. If another option remains to be
221 * processed, the return value of the function is 0 and *tptrp points to
222 * the 8-bit option type field (which is followed by the 8-bit option
223 * data length, followed by the option data). If no more options remain
224 * to be processed, the return value is -1 and *tptrp is NULL. If an
225 * error occurs, the return value is -1 and *tptrp is not NULL.
229 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
231 struct ip6_ext *ip6e;
235 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
236 (cmsg->cmsg_type != IPV6_HOPOPTS &&
237 cmsg->cmsg_type != IPV6_DSTOPTS))
240 /* message length validation */
241 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
243 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
244 hdrlen = (ip6e->ip6e_len + 1) << 3;
245 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
249 * If the caller does not specify the starting point,
250 * simply return the 1st option.
251 * Otherwise, search the option list for the next option.
253 lim = (u_int8_t *)ip6e + hdrlen;
255 *tptrp = (u_int8_t *)(ip6e + 1);
257 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
260 *tptrp = *tptrp + optlen;
262 if (*tptrp >= lim) { /* there is no option */
267 * Finally, checks if the next option is safely stored in the
270 if (ip6optlen(*tptrp, lim) == 0)
277 * This function is similar to the inet6_option_next() function,
278 * except this function lets the caller specify the option type to be
279 * searched for, instead of always returning the next option in the
280 * ancillary data object.
281 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
282 * it's a typo. The variable should be type of u_int8_t **.
285 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
287 struct ip6_ext *ip6e;
289 u_int8_t *optp, *lim;
291 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
292 (cmsg->cmsg_type != IPV6_HOPOPTS &&
293 cmsg->cmsg_type != IPV6_DSTOPTS))
296 /* message length validation */
297 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
299 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
300 hdrlen = (ip6e->ip6e_len + 1) << 3;
301 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
305 * If the caller does not specify the starting point,
306 * search from the beginning of the option list.
307 * Otherwise, search from *the next option* of the specified point.
309 lim = (u_int8_t *)ip6e + hdrlen;
311 *tptrp = (u_int8_t *)(ip6e + 1);
313 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
316 *tptrp = *tptrp + optlen;
318 for (optp = *tptrp; optp < lim; optp += optlen) {
323 if ((optlen = ip6optlen(optp, lim)) == 0)
333 * Calculate the length of a given IPv6 option. Also checks
334 * if the option is safely stored in user's buffer according to the
335 * calculated length and the limitation of the buffer.
338 ip6optlen(u_int8_t *opt, u_int8_t *lim)
342 if (*opt == IP6OPT_PAD1)
345 /* is there enough space to store type and len? */
348 optlen = *(opt + 1) + 2;
350 if (opt + optlen <= lim)
357 inet6_insert_padopt(u_char *p, int len)
368 memset(&p[2], 0, len - 2);
374 * The following functions are defined in RFC3542, which is a successor
379 inet6_opt_init(void *extbuf, socklen_t extlen)
381 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
384 if (extlen <= 0 || (extlen % 8))
386 ext->ip6e_len = (extlen >> 3) - 1;
389 return(2); /* sizeof the next and the length fields */
393 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
394 socklen_t len, u_int8_t align, void **databufp)
396 int currentlen = offset, padlen = 0;
399 * The option type must have a value from 2 to 255, inclusive.
400 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
406 * The option data length must have a value between 0 and 255,
407 * inclusive, and is the length of the option data that follows.
413 * The align parameter must have a value of 1, 2, 4, or 8.
414 * The align value can not exceed the value of len.
416 if (align != 1 && align != 2 && align != 4 && align != 8)
421 /* Calculate the padding length. */
422 currentlen += 2 + len; /* 2 means "type + len" */
423 if (currentlen % align)
424 padlen = align - (currentlen % align);
426 /* The option must fit in the extension header buffer. */
427 currentlen += padlen;
428 if (extlen && /* XXX: right? */
433 u_int8_t *optp = (u_int8_t *)extbuf + offset;
436 /* insert a Pad1 option */
439 } else if (padlen > 0) {
440 /* insert a PadN option for alignment */
441 *optp++ = IP6OPT_PADN;
442 *optp++ = padlen - 2;
443 memset(optp, 0, padlen - 2);
444 optp += (padlen - 2);
457 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
459 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
463 int padlen = updatelen - offset;
465 if (updatelen > extlen)
468 padp = (u_int8_t *)extbuf + offset;
471 else if (padlen > 0) {
472 *padp++ = IP6OPT_PADN;
473 *padp++ = (padlen - 2);
474 memset(padp, 0, padlen - 2);
482 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
485 memcpy((u_int8_t *)databuf + offset, val, vallen);
486 return(offset + vallen);
490 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
491 socklen_t *lenp, void **databufp)
493 u_int8_t *optp, *lim;
496 /* Validate extlen. XXX: is the variable really necessary?? */
497 if (extlen == 0 || (extlen % 8))
499 lim = (u_int8_t *)extbuf + extlen;
502 * If this is the first time this function called for this options
503 * header, simply return the 1st option.
504 * Otherwise, search the option list for the next option.
507 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
509 optp = (u_int8_t *)extbuf + offset;
511 /* Find the next option skipping any padding options. */
518 if ((optlen = ip6optlen(optp, lim)) == 0)
523 if ((optlen = ip6optlen(optp, lim)) == 0)
527 *databufp = optp + 2;
528 return(optp + optlen - (u_int8_t *)extbuf);
533 *databufp = NULL; /* for safety */
538 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
539 socklen_t *lenp, void **databufp)
541 u_int8_t *optp, *lim;
544 /* Validate extlen. XXX: is the variable really necessary?? */
545 if (extlen == 0 || (extlen % 8))
547 lim = (u_int8_t *)extbuf + extlen;
550 * If this is the first time this function called for this options
551 * header, simply return the 1st option.
552 * Otherwise, search the option list for the next option.
555 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
557 optp = (u_int8_t *)extbuf + offset;
559 /* Find the specified option */
561 if ((optlen = ip6optlen(optp, lim)) == 0)
564 if (*optp == type) { /* found */
566 *databufp = optp + 2;
567 return(optp + optlen - (u_int8_t *)extbuf);
574 *databufp = NULL; /* for safety */
579 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
582 /* we can't assume alignment here */
583 memcpy(val, (u_int8_t *)databuf + offset, vallen);
585 return(offset + vallen);