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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 1.5 2006/07/08 01:04:28 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)
109 * If this is the first option, allocate space for the
110 * first 2 bytes(for next header and length fields) of
113 if (bp == (u_char *)eh) {
118 /* calculate pad length before the option. */
119 off = bp - (u_char *)eh;
120 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
124 inet6_insert_padopt(bp, padlen);
125 cmsg->cmsg_len += padlen;
128 /* copy the option */
129 if (typep[0] == IP6OPT_PAD1)
132 optlen = typep[1] + 2;
133 memcpy(bp, typep, optlen);
135 cmsg->cmsg_len += optlen;
137 /* calculate pad length after the option and insert the padding */
138 off = bp - (u_char *)eh;
139 padlen = ((off + 7) & ~7) - off;
140 inet6_insert_padopt(bp, padlen);
142 cmsg->cmsg_len += padlen;
144 /* update the length field of the ip6 option header */
145 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
151 * This function appends a Hop-by-Hop option or a Destination option
152 * into an ancillary data object that has been initialized by
153 * inet6_option_init(). This function returns a pointer to the 8-bit
154 * option type field that starts the option on success, or NULL on an
156 * The difference between this function and inet6_option_append() is
157 * that the latter copies the contents of a previously built option into
158 * the ancillary data object while the current function returns a
159 * pointer to the space in the data object where the option's TLV must
160 * then be built by the caller.
164 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
167 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
169 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
171 /* argument validation */
172 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
174 if (plusy < 0 || plusy > 7)
178 * If this is the first option, allocate space for the
179 * first 2 bytes(for next header and length fields) of
182 if (bp == (u_char *)eh) {
187 /* calculate pad length before the option. */
188 off = bp - (u_char *)eh;
189 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
193 inet6_insert_padopt(bp, padlen);
194 cmsg->cmsg_len += padlen;
197 /* keep space to store specified length of data */
200 cmsg->cmsg_len += datalen;
202 /* calculate pad length after the option and insert the padding */
203 off = bp - (u_char *)eh;
204 padlen = ((off + 7) & ~7) - off;
205 inet6_insert_padopt(bp, padlen);
207 cmsg->cmsg_len += padlen;
209 /* update the length field of the ip6 option header */
210 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
216 * This function processes the next Hop-by-Hop option or Destination
217 * option in an ancillary data object. If another option remains to be
218 * processed, the return value of the function is 0 and *tptrp points to
219 * the 8-bit option type field (which is followed by the 8-bit option
220 * data length, followed by the option data). If no more options remain
221 * to be processed, the return value is -1 and *tptrp is NULL. If an
222 * error occurs, the return value is -1 and *tptrp is not NULL.
226 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
228 struct ip6_ext *ip6e;
232 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
233 (cmsg->cmsg_type != IPV6_HOPOPTS &&
234 cmsg->cmsg_type != IPV6_DSTOPTS))
237 /* message length validation */
238 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
240 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
241 hdrlen = (ip6e->ip6e_len + 1) << 3;
242 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
246 * If the caller does not specify the starting point,
247 * simply return the 1st option.
248 * Otherwise, search the option list for the next option.
250 lim = (u_int8_t *)ip6e + hdrlen;
252 *tptrp = (u_int8_t *)(ip6e + 1);
254 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
257 *tptrp = *tptrp + optlen;
259 if (*tptrp >= lim) { /* there is no option */
264 * Finally, checks if the next option is safely stored in the
267 if (ip6optlen(*tptrp, lim) == 0)
274 * This function is similar to the inet6_option_next() function,
275 * except this function lets the caller specify the option type to be
276 * searched for, instead of always returning the next option in the
277 * ancillary data object.
278 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
279 * it's a typo. The variable should be type of u_int8_t **.
282 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
284 struct ip6_ext *ip6e;
286 u_int8_t *optp, *lim;
288 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
289 (cmsg->cmsg_type != IPV6_HOPOPTS &&
290 cmsg->cmsg_type != IPV6_DSTOPTS))
293 /* message length validation */
294 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
296 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
297 hdrlen = (ip6e->ip6e_len + 1) << 3;
298 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
302 * If the caller does not specify the starting point,
303 * search from the beginning of the option list.
304 * Otherwise, search from *the next option* of the specified point.
306 lim = (u_int8_t *)ip6e + hdrlen;
308 *tptrp = (u_int8_t *)(ip6e + 1);
310 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
313 *tptrp = *tptrp + optlen;
315 for (optp = *tptrp; optp < lim; optp += optlen) {
320 if ((optlen = ip6optlen(optp, lim)) == 0)
330 * Calculate the length of a given IPv6 option. Also checks
331 * if the option is safely stored in user's buffer according to the
332 * calculated length and the limitation of the buffer.
335 ip6optlen(u_int8_t *opt, u_int8_t *lim)
339 if (*opt == IP6OPT_PAD1)
342 /* is there enough space to store type and len? */
345 optlen = *(opt + 1) + 2;
347 if (opt + optlen <= lim)
354 inet6_insert_padopt(u_char *p, int len)
365 memset(&p[2], 0, len - 2);