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29 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.1 1999/12/16 18:32:01 shin Exp $
30 * $DragonFly: src/lib/libc/net/ip6opt.c,v 1.4 2005/11/13 02:04:47 swildner Exp $
33 #include <sys/param.h>
34 #include <sys/types.h>
35 #include <sys/socket.h>
37 #include <netinet/in.h>
38 #include <netinet/ip6.h>
43 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
44 static void inet6_insert_padopt(u_char *p, int len);
47 * This function returns the number of bytes required to hold an option
48 * when it is stored as ancillary data, including the cmsghdr structure
49 * at the beginning, and any padding at the end (to make its size a
50 * multiple of 8 bytes). The argument is the size of the structure
51 * defining the option, which must include any pad bytes at the
52 * beginning (the value y in the alignment term "xn + y"), the type
53 * byte, the length byte, and the option data.
56 inet6_option_space(int 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(void *bp, struct cmsghdr **cmsgp, int type)
70 struct cmsghdr *ch = (struct cmsghdr *)bp;
72 /* argument validation */
73 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
76 ch->cmsg_level = IPPROTO_IPV6;
78 ch->cmsg_len = CMSG_LEN(0);
85 * This function appends a Hop-by-Hop option or a Destination option
86 * into an ancillary data object that has been initialized by
87 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
89 * multx is the value x in the alignment term "xn + y" described
90 * earlier. It must have a value of 1, 2, 4, or 8.
91 * plusy is the value y in the alignment term "xn + y" described
92 * earlier. It must have a value between 0 and 7, inclusive.
95 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
98 int padlen, optlen, off;
99 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
100 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
102 /* argument validation */
103 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
105 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)) -
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)) -
195 inet6_insert_padopt(bp, padlen);
196 cmsg->cmsg_len += padlen;
199 /* keep space to store specified length of data */
202 cmsg->cmsg_len += datalen;
204 /* calculate pad length after the option and insert the padding */
205 off = bp - (u_char *)eh;
206 padlen = ((off + 7) & ~7) - off;
207 inet6_insert_padopt(bp, padlen);
209 cmsg->cmsg_len += padlen;
211 /* update the length field of the ip6 option header */
212 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
218 * This function processes the next Hop-by-Hop option or Destination
219 * option in an ancillary data object. If another option remains to be
220 * processed, the return value of the function is 0 and *tptrp points to
221 * the 8-bit option type field (which is followed by the 8-bit option
222 * data length, followed by the option data). If no more options remain
223 * to be processed, the return value is -1 and *tptrp is NULL. If an
224 * error occurs, the return value is -1 and *tptrp is not NULL.
228 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
230 struct ip6_ext *ip6e;
234 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
235 (cmsg->cmsg_type != IPV6_HOPOPTS &&
236 cmsg->cmsg_type != IPV6_DSTOPTS))
239 /* message length validation */
240 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
242 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
243 hdrlen = (ip6e->ip6e_len + 1) << 3;
244 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
248 * If the caller does not specify the starting point,
249 * simply return the 1st option.
250 * Otherwise, search the option list for the next option.
252 lim = (u_int8_t *)ip6e + hdrlen;
254 *tptrp = (u_int8_t *)(ip6e + 1);
256 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
259 *tptrp = *tptrp + optlen;
261 if (*tptrp >= lim) { /* there is no option */
266 * Finally, checks if the next option is safely stored in the
269 if (ip6optlen(*tptrp, lim) == 0)
276 * This function is similar to the inet6_option_next() function,
277 * except this function lets the caller specify the option type to be
278 * searched for, instead of always returning the next option in the
279 * ancillary data object.
280 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
281 * it's a typo. The variable should be type of u_int8_t **.
284 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
286 struct ip6_ext *ip6e;
288 u_int8_t *optp, *lim;
290 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
291 (cmsg->cmsg_type != IPV6_HOPOPTS &&
292 cmsg->cmsg_type != IPV6_DSTOPTS))
295 /* message length validation */
296 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
298 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
299 hdrlen = (ip6e->ip6e_len + 1) << 3;
300 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
304 * If the caller does not specify the starting point,
305 * search from the beginning of the option list.
306 * Otherwise, search from *the next option* of the specified point.
308 lim = (u_int8_t *)ip6e + hdrlen;
310 *tptrp = (u_int8_t *)(ip6e + 1);
312 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
315 *tptrp = *tptrp + optlen;
317 for (optp = *tptrp; optp < lim; optp += optlen) {
322 if ((optlen = ip6optlen(optp, lim)) == 0)
332 * Calculate the length of a given IPv6 option. Also checks
333 * if the option is safely stored in user's buffer according to the
334 * calculated length and the limitation of the buffer.
337 ip6optlen(u_int8_t *opt, u_int8_t *lim)
341 if (*opt == IP6OPT_PAD1)
344 /* is there enough space to store type and len? */
347 optlen = *(opt + 1) + 2;
349 if (opt + optlen <= lim)
356 inet6_insert_padopt(u_char *p, int len)
367 memset(&p[2], 0, len - 2);