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 $
32 * $DragonFly: src/lib/libc/net/ip6opt.c,v 1.6 2007/05/29 10:58:11 hasso Exp $
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(int nbytes)
60 nbytes += 2; /* we need space for nxt-hdr and length fields */
61 return(CMSG_SPACE((nbytes + 7) & ~7));
65 * This function is called once per ancillary data object that will
66 * contain either Hop-by-Hop or Destination options. It returns 0 on
67 * success or -1 on an error.
70 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
72 struct cmsghdr *ch = (struct cmsghdr *)bp;
74 /* argument validation */
75 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
78 ch->cmsg_level = IPPROTO_IPV6;
80 ch->cmsg_len = CMSG_LEN(0);
87 * This function appends a Hop-by-Hop option or a Destination option
88 * into an ancillary data object that has been initialized by
89 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
91 * multx is the value x in the alignment term "xn + y" described
92 * earlier. It must have a value of 1, 2, 4, or 8.
93 * plusy is the value y in the alignment term "xn + y" described
94 * earlier. It must have a value between 0 and 7, inclusive.
97 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
100 int padlen, optlen, off;
101 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
102 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
104 /* argument validation */
105 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
107 if (plusy < 0 || plusy > 7)
111 * If this is the first option, allocate space for the
112 * first 2 bytes(for next header and length fields) of
115 if (bp == (u_char *)eh) {
120 /* calculate pad length before the option. */
121 off = bp - (u_char *)eh;
122 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
125 padlen %= multx; /* keep the pad as short as possible */
127 inet6_insert_padopt(bp, padlen);
128 cmsg->cmsg_len += padlen;
131 /* copy the option */
132 if (typep[0] == IP6OPT_PAD1)
135 optlen = typep[1] + 2;
136 memcpy(bp, typep, optlen);
138 cmsg->cmsg_len += optlen;
140 /* calculate pad length after the option and insert the padding */
141 off = bp - (u_char *)eh;
142 padlen = ((off + 7) & ~7) - off;
143 inet6_insert_padopt(bp, padlen);
145 cmsg->cmsg_len += padlen;
147 /* update the length field of the ip6 option header */
148 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
154 * This function appends a Hop-by-Hop option or a Destination option
155 * into an ancillary data object that has been initialized by
156 * inet6_option_init(). This function returns a pointer to the 8-bit
157 * option type field that starts the option on success, or NULL on an
159 * The difference between this function and inet6_option_append() is
160 * that the latter copies the contents of a previously built option into
161 * the ancillary data object while the current function returns a
162 * pointer to the space in the data object where the option's TLV must
163 * then be built by the caller.
167 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
170 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
172 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
174 /* argument validation */
175 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
177 if (plusy < 0 || plusy > 7)
181 * If this is the first option, allocate space for the
182 * first 2 bytes(for next header and length fields) of
185 if (bp == (u_char *)eh) {
190 /* calculate pad length before the option. */
191 off = bp - (u_char *)eh;
192 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
195 padlen %= multx; /* keep the pad as short as possible */
197 inet6_insert_padopt(bp, padlen);
198 cmsg->cmsg_len += padlen;
201 /* keep space to store specified length of data */
204 cmsg->cmsg_len += datalen;
206 /* calculate pad length after the option and insert the padding */
207 off = bp - (u_char *)eh;
208 padlen = ((off + 7) & ~7) - off;
209 inet6_insert_padopt(bp, padlen);
211 cmsg->cmsg_len += padlen;
213 /* update the length field of the ip6 option header */
214 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
220 * This function processes the next Hop-by-Hop option or Destination
221 * option in an ancillary data object. If another option remains to be
222 * processed, the return value of the function is 0 and *tptrp points to
223 * the 8-bit option type field (which is followed by the 8-bit option
224 * data length, followed by the option data). If no more options remain
225 * to be processed, the return value is -1 and *tptrp is NULL. If an
226 * error occurs, the return value is -1 and *tptrp is not NULL.
230 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
232 struct ip6_ext *ip6e;
236 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
237 (cmsg->cmsg_type != IPV6_HOPOPTS &&
238 cmsg->cmsg_type != IPV6_DSTOPTS))
241 /* message length validation */
242 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
244 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
245 hdrlen = (ip6e->ip6e_len + 1) << 3;
246 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
250 * If the caller does not specify the starting point,
251 * simply return the 1st option.
252 * Otherwise, search the option list for the next option.
254 lim = (u_int8_t *)ip6e + hdrlen;
256 *tptrp = (u_int8_t *)(ip6e + 1);
258 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
261 *tptrp = *tptrp + optlen;
263 if (*tptrp >= lim) { /* there is no option */
268 * Finally, checks if the next option is safely stored in the
271 if (ip6optlen(*tptrp, lim) == 0)
278 * This function is similar to the inet6_option_next() function,
279 * except this function lets the caller specify the option type to be
280 * searched for, instead of always returning the next option in the
281 * ancillary data object.
282 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
283 * it's a typo. The variable should be type of u_int8_t **.
286 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
288 struct ip6_ext *ip6e;
290 u_int8_t *optp, *lim;
292 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
293 (cmsg->cmsg_type != IPV6_HOPOPTS &&
294 cmsg->cmsg_type != IPV6_DSTOPTS))
297 /* message length validation */
298 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
300 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
301 hdrlen = (ip6e->ip6e_len + 1) << 3;
302 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
306 * If the caller does not specify the starting point,
307 * search from the beginning of the option list.
308 * Otherwise, search from *the next option* of the specified point.
310 lim = (u_int8_t *)ip6e + hdrlen;
312 *tptrp = (u_int8_t *)(ip6e + 1);
314 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
317 *tptrp = *tptrp + optlen;
319 for (optp = *tptrp; optp < lim; optp += optlen) {
324 if ((optlen = ip6optlen(optp, lim)) == 0)
334 * Calculate the length of a given IPv6 option. Also checks
335 * if the option is safely stored in user's buffer according to the
336 * calculated length and the limitation of the buffer.
339 ip6optlen(u_int8_t *opt, u_int8_t *lim)
343 if (*opt == IP6OPT_PAD1)
346 /* is there enough space to store type and len? */
349 optlen = *(opt + 1) + 2;
351 if (opt + optlen <= lim)
358 inet6_insert_padopt(u_char *p, int len)
369 memset(&p[2], 0, len - 2);
375 * The following functions are defined in RFC3542, which is a successor
380 inet6_opt_init(void *extbuf, socklen_t extlen)
382 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
384 if (extlen < 0 || (extlen % 8))
390 ext->ip6e_len = (extlen >> 3) - 1;
393 return(2); /* sizeof the next and the length fields */
397 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
398 socklen_t len, u_int8_t align, void **databufp)
400 int currentlen = offset, padlen = 0;
403 * The option type must have a value from 2 to 255, inclusive.
404 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
410 * The option data length must have a value between 0 and 255,
411 * inclusive, and is the length of the option data that follows.
413 if (len < 0 || len > 255)
417 * The align parameter must have a value of 1, 2, 4, or 8.
418 * The align value can not exceed the value of len.
420 if (align != 1 && align != 2 && align != 4 && align != 8)
425 /* Calculate the padding length. */
426 currentlen += 2 + len; /* 2 means "type + len" */
427 if (currentlen % align)
428 padlen = align - (currentlen % align);
430 /* The option must fit in the extension header buffer. */
431 currentlen += padlen;
432 if (extlen && /* XXX: right? */
437 u_int8_t *optp = (u_int8_t *)extbuf + offset;
440 /* insert a Pad1 option */
443 } else if (padlen > 0) {
444 /* insert a PadN option for alignment */
445 *optp++ = IP6OPT_PADN;
446 *optp++ = padlen - 2;
447 memset(optp, 0, padlen - 2);
448 optp += (padlen - 2);
461 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
463 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;;
467 int padlen = updatelen - offset;
469 if (updatelen > extlen)
472 padp = (u_int8_t *)extbuf + offset;
475 else if (padlen > 0) {
476 *padp++ = IP6OPT_PADN;
477 *padp++ = (padlen - 2);
478 memset(padp, 0, padlen - 2);
486 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
489 memcpy((u_int8_t *)databuf + offset, val, vallen);
490 return(offset + vallen);
494 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
495 socklen_t *lenp, void **databufp)
497 u_int8_t *optp, *lim;
500 /* Validate extlen. XXX: is the variable really necessary?? */
501 if (extlen == 0 || (extlen % 8))
503 lim = (u_int8_t *)extbuf + extlen;
506 * If this is the first time this function called for this options
507 * header, simply return the 1st option.
508 * Otherwise, search the option list for the next option.
511 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
513 optp = (u_int8_t *)extbuf + offset;
515 /* Find the next option skipping any padding options. */
522 if ((optlen = ip6optlen(optp, lim)) == 0)
527 if ((optlen = ip6optlen(optp, lim)) == 0)
531 *databufp = optp + 2;
532 return(optp + optlen - (u_int8_t *)extbuf);
537 *databufp = NULL; /* for safety */
542 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
543 socklen_t *lenp, void **databufp)
545 u_int8_t *optp, *lim;
548 /* Validate extlen. XXX: is the variable really necessary?? */
549 if (extlen == 0 || (extlen % 8))
551 lim = (u_int8_t *)extbuf + extlen;
554 * If this is the first time this function called for this options
555 * header, simply return the 1st option.
556 * Otherwise, search the option list for the next option.
559 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
561 optp = (u_int8_t *)extbuf + offset;
563 /* Find the specified option */
565 if ((optlen = ip6optlen(optp, lim)) == 0)
568 if (*optp == type) { /* found */
570 *databufp = optp + 2;
571 return(optp + optlen - (u_int8_t *)extbuf);
578 *databufp = NULL; /* for safety */
583 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
586 /* we can't assume alignment here */
587 memcpy(val, (u_int8_t *)databuf + offset, vallen);
589 return(offset + vallen);