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29 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.1 1999/12/16 18:32:01 shin Exp $
32 #include <sys/param.h>
33 #include <sys/types.h>
34 #include <sys/socket.h>
36 #include <netinet/in.h>
37 #include <netinet/ip6.h>
42 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
43 static void inet6_insert_padopt(u_char *p, int len);
46 * This function returns the number of bytes required to hold an option
47 * when it is stored as ancillary data, including the cmsghdr structure
48 * at the beginning, and any padding at the end (to make its size a
49 * multiple of 8 bytes). The argument is the size of the structure
50 * defining the option, which must include any pad bytes at the
51 * beginning (the value y in the alignment term "xn + y"), the type
52 * byte, the length byte, and the option data.
55 inet6_option_space(nbytes)
58 nbytes += 2; /* we need space for nxt-hdr and length fields */
59 return(CMSG_SPACE((nbytes + 7) & ~7));
63 * This function is called once per ancillary data object that will
64 * contain either Hop-by-Hop or Destination options. It returns 0 on
65 * success or -1 on an error.
68 inet6_option_init(bp, cmsgp, type)
70 struct cmsghdr **cmsgp;
73 register struct cmsghdr *ch = (struct cmsghdr *)bp;
75 /* argument validation */
76 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
79 ch->cmsg_level = IPPROTO_IPV6;
81 ch->cmsg_len = CMSG_LEN(0);
88 * This function appends a Hop-by-Hop option or a Destination option
89 * into an ancillary data object that has been initialized by
90 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
92 * multx is the value x in the alignment term "xn + y" described
93 * earlier. It must have a value of 1, 2, 4, or 8.
94 * plusy is the value y in the alignment term "xn + y" described
95 * earlier. It must have a value between 0 and 7, inclusive.
98 inet6_option_append(cmsg, typep, multx, plusy)
100 const u_int8_t *typep;
104 int padlen, optlen, off;
105 register u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
106 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
108 /* argument validation */
109 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
111 if (plusy < 0 || plusy > 7)
117 * If this is the first option, allocate space for the
118 * first 2 bytes(for next header and length fields) of
121 if (bp == (u_char *)eh) {
126 /* calculate pad length before the option. */
127 off = bp - (u_char *)eh;
128 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
132 inet6_insert_padopt(bp, padlen);
133 cmsg->cmsg_len += padlen;
136 /* copy the option */
137 if (typep[0] == IP6OPT_PAD1)
140 optlen = typep[1] + 2;
141 memcpy(bp, typep, optlen);
143 cmsg->cmsg_len += optlen;
145 /* calculate pad length after the option and insert the padding */
146 off = bp - (u_char *)eh;
147 padlen = ((off + 7) & ~7) - off;
148 inet6_insert_padopt(bp, padlen);
150 cmsg->cmsg_len += padlen;
152 /* update the length field of the ip6 option header */
153 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
159 * This function appends a Hop-by-Hop option or a Destination option
160 * into an ancillary data object that has been initialized by
161 * inet6_option_init(). This function returns a pointer to the 8-bit
162 * option type field that starts the option on success, or NULL on an
164 * The difference between this function and inet6_option_append() is
165 * that the latter copies the contents of a previously built option into
166 * the ancillary data object while the current function returns a
167 * pointer to the space in the data object where the option's TLV must
168 * then be built by the caller.
172 inet6_option_alloc(cmsg, datalen, multx, plusy)
173 struct cmsghdr *cmsg;
179 register u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
181 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
183 /* argument validation */
184 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
186 if (plusy < 0 || plusy > 7)
190 * If this is the first option, allocate space for the
191 * first 2 bytes(for next header and length fields) of
194 if (bp == (u_char *)eh) {
199 /* calculate pad length before the option. */
200 off = bp - (u_char *)eh;
201 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
205 inet6_insert_padopt(bp, padlen);
206 cmsg->cmsg_len += padlen;
209 /* keep space to store specified length of data */
212 cmsg->cmsg_len += datalen;
214 /* calculate pad length after the option and insert the padding */
215 off = bp - (u_char *)eh;
216 padlen = ((off + 7) & ~7) - off;
217 inet6_insert_padopt(bp, padlen);
219 cmsg->cmsg_len += padlen;
221 /* update the length field of the ip6 option header */
222 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
228 * This function processes the next Hop-by-Hop option or Destination
229 * option in an ancillary data object. If another option remains to be
230 * processed, the return value of the function is 0 and *tptrp points to
231 * the 8-bit option type field (which is followed by the 8-bit option
232 * data length, followed by the option data). If no more options remain
233 * to be processed, the return value is -1 and *tptrp is NULL. If an
234 * error occurs, the return value is -1 and *tptrp is not NULL.
238 inet6_option_next(cmsg, tptrp)
239 const struct cmsghdr *cmsg;
242 struct ip6_ext *ip6e;
246 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
247 (cmsg->cmsg_type != IPV6_HOPOPTS &&
248 cmsg->cmsg_type != IPV6_DSTOPTS))
251 /* message length validation */
252 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
254 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
255 hdrlen = (ip6e->ip6e_len + 1) << 3;
256 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
260 * If the caller does not specify the starting point,
261 * simply return the 1st option.
262 * Otherwise, search the option list for the next option.
264 lim = (u_int8_t *)ip6e + hdrlen;
266 *tptrp = (u_int8_t *)(ip6e + 1);
268 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
271 *tptrp = *tptrp + optlen;
273 if (*tptrp >= lim) { /* there is no option */
278 * Finally, checks if the next option is safely stored in the
281 if (ip6optlen(*tptrp, lim) == 0)
288 * This function is similar to the inet6_option_next() function,
289 * except this function lets the caller specify the option type to be
290 * searched for, instead of always returning the next option in the
291 * ancillary data object.
292 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
293 * it's a typo. The variable should be type of u_int8_t **.
296 inet6_option_find(cmsg, tptrp, type)
297 const struct cmsghdr *cmsg;
301 struct ip6_ext *ip6e;
303 u_int8_t *optp, *lim;
305 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
306 (cmsg->cmsg_type != IPV6_HOPOPTS &&
307 cmsg->cmsg_type != IPV6_DSTOPTS))
310 /* message length validation */
311 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
313 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
314 hdrlen = (ip6e->ip6e_len + 1) << 3;
315 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
319 * If the caller does not specify the starting point,
320 * search from the beginning of the option list.
321 * Otherwise, search from *the next option* of the specified point.
323 lim = (u_int8_t *)ip6e + hdrlen;
325 *tptrp = (u_int8_t *)(ip6e + 1);
327 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
330 *tptrp = *tptrp + optlen;
332 for (optp = *tptrp; optp < lim; optp += optlen) {
337 if ((optlen = ip6optlen(optp, lim)) == 0)
347 * Calculate the length of a given IPv6 option. Also checks
348 * if the option is safely stored in user's buffer according to the
349 * calculated length and the limitation of the buffer.
357 if (*opt == IP6OPT_PAD1)
360 /* is there enough space to store type and len? */
363 optlen = *(opt + 1) + 2;
365 if (opt + optlen <= lim)
372 inet6_insert_padopt(u_char *p, int len)
383 memset(&p[2], 0, len - 2);