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/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);
48 #ifndef IPV6_2292HOPOPTS
49 #define IPV6_2292HOPOPTS 22
51 #ifndef IPV6_2292DSTOPTS
52 #define IPV6_2292DSTOPTS 23
55 #define is_ipv6_hopopts(x) \
56 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
57 #define is_ipv6_dstopts(x) \
58 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
61 * This function returns the number of bytes required to hold an option
62 * when it is stored as ancillary data, including the cmsghdr structure
63 * at the beginning, and any padding at the end (to make its size a
64 * multiple of 8 bytes). The argument is the size of the structure
65 * defining the option, which must include any pad bytes at the
66 * beginning (the value y in the alignment term "xn + y"), the type
67 * byte, the length byte, and the option data.
70 inet6_option_space(int nbytes)
72 nbytes += 2; /* we need space for nxt-hdr and length fields */
73 return(CMSG_SPACE((nbytes + 7) & ~7));
77 * This function is called once per ancillary data object that will
78 * contain either Hop-by-Hop or Destination options. It returns 0 on
79 * success or -1 on an error.
82 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
84 struct cmsghdr *ch = (struct cmsghdr *)bp;
86 /* argument validation */
87 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
90 ch->cmsg_level = IPPROTO_IPV6;
92 ch->cmsg_len = CMSG_LEN(0);
99 * This function appends a Hop-by-Hop option or a Destination option
100 * into an ancillary data object that has been initialized by
101 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
103 * multx is the value x in the alignment term "xn + y" described
104 * earlier. It must have a value of 1, 2, 4, or 8.
105 * plusy is the value y in the alignment term "xn + y" described
106 * earlier. It must have a value between 0 and 7, inclusive.
109 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
112 int padlen, optlen, off;
113 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
114 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
116 /* argument validation */
117 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
119 if (plusy < 0 || plusy > 7)
123 * If this is the first option, allocate space for the
124 * first 2 bytes(for next header and length fields) of
127 if (bp == (u_char *)eh) {
132 /* calculate pad length before the option. */
133 off = bp - (u_char *)eh;
134 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
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 = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
207 padlen %= multx; /* keep the pad as short as possible */
209 inet6_insert_padopt(bp, padlen);
210 cmsg->cmsg_len += padlen;
213 /* keep space to store specified length of data */
216 cmsg->cmsg_len += datalen;
218 /* calculate pad length after the option and insert the padding */
219 off = bp - (u_char *)eh;
220 padlen = ((off + 7) & ~7) - off;
221 inet6_insert_padopt(bp, padlen);
223 cmsg->cmsg_len += padlen;
225 /* update the length field of the ip6 option header */
226 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
232 * This function processes the next Hop-by-Hop option or Destination
233 * option in an ancillary data object. If another option remains to be
234 * processed, the return value of the function is 0 and *tptrp points to
235 * the 8-bit option type field (which is followed by the 8-bit option
236 * data length, followed by the option data). If no more options remain
237 * to be processed, the return value is -1 and *tptrp is NULL. If an
238 * error occurs, the return value is -1 and *tptrp is not NULL.
242 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
244 struct ip6_ext *ip6e;
248 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
249 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
250 !is_ipv6_dstopts(cmsg->cmsg_type)))
253 /* message length validation */
254 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
256 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
257 hdrlen = (ip6e->ip6e_len + 1) << 3;
258 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
262 * If the caller does not specify the starting point,
263 * simply return the 1st option.
264 * Otherwise, search the option list for the next option.
266 lim = (u_int8_t *)ip6e + hdrlen;
268 *tptrp = (u_int8_t *)(ip6e + 1);
270 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
273 *tptrp = *tptrp + optlen;
275 if (*tptrp >= lim) { /* there is no option */
280 * Finally, checks if the next option is safely stored in the
283 if (ip6optlen(*tptrp, lim) == 0)
290 * This function is similar to the inet6_option_next() function,
291 * except this function lets the caller specify the option type to be
292 * searched for, instead of always returning the next option in the
293 * ancillary data object.
294 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
295 * it's a typo. The variable should be type of u_int8_t **.
298 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
300 struct ip6_ext *ip6e;
302 u_int8_t *optp, *lim;
304 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
305 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
306 !is_ipv6_dstopts(cmsg->cmsg_type)))
309 /* message length validation */
310 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
312 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
313 hdrlen = (ip6e->ip6e_len + 1) << 3;
314 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
318 * If the caller does not specify the starting point,
319 * search from the beginning of the option list.
320 * Otherwise, search from *the next option* of the specified point.
322 lim = (u_int8_t *)ip6e + hdrlen;
324 *tptrp = (u_int8_t *)(ip6e + 1);
326 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
329 *tptrp = *tptrp + optlen;
331 for (optp = *tptrp; optp < lim; optp += optlen) {
336 if ((optlen = ip6optlen(optp, lim)) == 0)
346 * Calculate the length of a given IPv6 option. Also checks
347 * if the option is safely stored in user's buffer according to the
348 * calculated length and the limitation of the buffer.
351 ip6optlen(u_int8_t *opt, u_int8_t *lim)
355 if (*opt == IP6OPT_PAD1)
358 /* is there enough space to store type and len? */
361 optlen = *(opt + 1) + 2;
363 if (opt + optlen <= lim)
370 inet6_insert_padopt(u_char *p, int len)
381 memset(&p[2], 0, len - 2);
387 * The following functions are defined in RFC3542, which is a successor
392 inet6_opt_init(void *extbuf, socklen_t extlen)
394 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
397 if (extlen <= 0 || (extlen % 8))
399 ext->ip6e_len = (extlen >> 3) - 1;
402 return(2); /* sizeof the next and the length fields */
406 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
407 socklen_t len, u_int8_t align, void **databufp)
409 int currentlen = offset, padlen = 0;
412 * The option type must have a value from 2 to 255, inclusive.
413 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
419 * The option data length must have a value between 0 and 255,
420 * inclusive, and is the length of the option data that follows.
422 if (len > 255 || len < 0 )
426 * The align parameter must have a value of 1, 2, 4, or 8.
427 * The align value can not exceed the value of len.
429 if (align != 1 && align != 2 && align != 4 && align != 8)
434 /* Calculate the padding length. */
435 currentlen += 2 + len; /* 2 means "type + len" */
436 if (currentlen % align)
437 padlen = align - (currentlen % align);
439 /* The option must fit in the extension header buffer. */
440 currentlen += padlen;
441 if (extlen && /* XXX: right? */
446 u_int8_t *optp = (u_int8_t *)extbuf + offset;
449 /* insert a Pad1 option */
453 else if (padlen > 0) {
454 /* insert a PadN option for alignment */
455 *optp++ = IP6OPT_PADN;
456 *optp++ = padlen - 2;
457 memset(optp, 0, padlen - 2);
458 optp += (padlen - 2);
471 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
473 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
477 int padlen = updatelen - offset;
479 if (updatelen > extlen)
482 padp = (u_int8_t *)extbuf + offset;
485 else if (padlen > 0) {
486 *padp++ = IP6OPT_PADN;
487 *padp++ = (padlen - 2);
488 memset(padp, 0, padlen - 2);
496 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
499 memcpy((u_int8_t *)databuf + offset, val, vallen);
500 return(offset + vallen);
504 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
505 socklen_t *lenp, void **databufp)
507 u_int8_t *optp, *lim;
510 /* Validate extlen. XXX: is the variable really necessary?? */
511 if (extlen == 0 || (extlen % 8))
513 lim = (u_int8_t *)extbuf + extlen;
516 * If this is the first time this function called for this options
517 * header, simply return the 1st option.
518 * Otherwise, search the option list for the next option.
521 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
524 optp = (u_int8_t *)extbuf + offset;
526 /* Find the next option skipping any padding options. */
533 if ((optlen = ip6optlen(optp, lim)) == 0)
538 if ((optlen = ip6optlen(optp, lim)) == 0)
542 *databufp = optp + 2;
543 return(optp + optlen - (u_int8_t *)extbuf);
548 *databufp = NULL; /* for safety */
553 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
554 socklen_t *lenp, void **databufp)
556 u_int8_t *optp, *lim;
559 /* Validate extlen. XXX: is the variable really necessary?? */
560 if (extlen == 0 || (extlen % 8))
562 lim = (u_int8_t *)extbuf + extlen;
565 * If this is the first time this function called for this options
566 * header, simply return the 1st option.
567 * Otherwise, search the option list for the next option.
570 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
573 optp = (u_int8_t *)extbuf + offset;
575 /* Find the specified option */
577 if ((optlen = ip6optlen(optp, lim)) == 0)
580 if (*optp == type) { /* found */
582 *databufp = optp + 2;
583 return(optp + optlen - (u_int8_t *)extbuf);
590 *databufp = NULL; /* for safety */
595 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
598 /* we can't assume alignment here */
599 memcpy(val, (u_int8_t *)databuf + offset, vallen);
601 return(offset + vallen);