[apple/libinfo.git] / gen.subproj / ip6opt.c

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.1 1999/12/16 18:32:01 shin Exp $
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <netinet/ip6.h>

#include <string.h>
#include <stdio.h>

static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
static void inet6_insert_padopt(u_char *p, int len);

/*
 * This function returns the number of bytes required to hold an option
 * when it is stored as ancillary data, including the cmsghdr structure
 * at the beginning, and any padding at the end (to make its size a
 * multiple of 8 bytes).  The argument is the size of the structure
 * defining the option, which must include any pad bytes at the
 * beginning (the value y in the alignment term "xn + y"), the type
 * byte, the length byte, and the option data.
 */
int
inet6_option_space(nbytes)
	int nbytes;
{
	nbytes += 2;	/* we need space for nxt-hdr and length fields */
	return(CMSG_SPACE((nbytes + 7) & ~7));
}

/*
 * This function is called once per ancillary data object that will
 * contain either Hop-by-Hop or Destination options.  It returns 0 on
 * success or -1 on an error.
 */
int
inet6_option_init(bp, cmsgp, type)
	void *bp;
	struct cmsghdr **cmsgp;
	int type;
{
	register struct cmsghdr *ch = (struct cmsghdr *)bp;

	/* argument validation */
	if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
		return(-1);
	
	ch->cmsg_level = IPPROTO_IPV6;
	ch->cmsg_type = type;
	ch->cmsg_len = CMSG_LEN(0);

	*cmsgp = ch;
	return(0);
}

/*
 * This function appends a Hop-by-Hop option or a Destination option
 * into an ancillary data object that has been initialized by
 * inet6_option_init().  This function returns 0 if it succeeds or -1 on
 * an error.
 * multx is the value x in the alignment term "xn + y" described
 * earlier.  It must have a value of 1, 2, 4, or 8.
 * plusy is the value y in the alignment term "xn + y" described
 * earlier.  It must have a value between 0 and 7, inclusive.
 */
int
inet6_option_append(cmsg, typep, multx, plusy)
	struct cmsghdr *cmsg;
	const u_int8_t *typep;
	int multx;
	int plusy;
{
	int padlen, optlen, off;
	register u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
	struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);

	/* argument validation */
	if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
		return(-1);
	if (plusy < 0 || plusy > 7)
		return(-1);
	if (typep[0] > 255)
		return(-1);

	/*
	 * If this is the first option, allocate space for the
	 * first 2 bytes(for next header and length fields) of
	 * the option header.
	 */
	if (bp == (u_char *)eh) {
		bp += 2;
		cmsg->cmsg_len += 2;
	}

	/* calculate pad length before the option. */
	off = bp - (u_char *)eh;
	padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
		(off % multx);
	padlen += plusy;
	/* insert padding */
	inet6_insert_padopt(bp, padlen);
	cmsg->cmsg_len += padlen;
	bp += padlen;

	/* copy the option */
	if (typep[0] == IP6OPT_PAD1)
		optlen = 1;
	else
		optlen = typep[1] + 2;
	memcpy(bp, typep, optlen);
	bp += optlen;
	cmsg->cmsg_len += optlen;

	/* calculate pad length after the option and insert the padding */
	off = bp - (u_char *)eh;
	padlen = ((off + 7) & ~7) - off;
	inet6_insert_padopt(bp, padlen);
	bp += padlen;
	cmsg->cmsg_len += padlen;

	/* update the length field of the ip6 option header */
	eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;

	return(0);
}

/*
 * This function appends a Hop-by-Hop option or a Destination option
 * into an ancillary data object that has been initialized by
 * inet6_option_init().  This function returns a pointer to the 8-bit
 * option type field that starts the option on success, or NULL on an
 * error.
 * The difference between this function and inet6_option_append() is
 * that the latter copies the contents of a previously built option into
 * the ancillary data object while the current function returns a
 * pointer to the space in the data object where the option's TLV must
 * then be built by the caller.
 * 
 */
u_int8_t *
inet6_option_alloc(cmsg, datalen, multx, plusy)
	struct cmsghdr *cmsg;
	int datalen;
	int multx;
	int plusy;
{
	int padlen, off;
	register u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
	u_int8_t *retval;
	struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);

	/* argument validation */
	if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
		return(NULL);
	if (plusy < 0 || plusy > 7)
		return(NULL);

	/*
	 * If this is the first option, allocate space for the
	 * first 2 bytes(for next header and length fields) of
	 * the option header.
	 */
	if (bp == (u_char *)eh) {
		bp += 2;
		cmsg->cmsg_len += 2;
	}

	/* calculate pad length before the option. */
	off = bp - (u_char *)eh;
	padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
		(off % multx);
	padlen += plusy;
	/* insert padding */
	inet6_insert_padopt(bp, padlen);
	cmsg->cmsg_len += padlen;
	bp += padlen;

	/* keep space to store specified length of data */
	retval = bp;
	bp += datalen;
	cmsg->cmsg_len += datalen;

	/* calculate pad length after the option and insert the padding */
	off = bp - (u_char *)eh;
	padlen = ((off + 7) & ~7) - off;
	inet6_insert_padopt(bp, padlen);
	bp += padlen;
	cmsg->cmsg_len += padlen;

	/* update the length field of the ip6 option header */
	eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;

	return(retval);
}

/*
 * This function processes the next Hop-by-Hop option or Destination
 * option in an ancillary data object.  If another option remains to be
 * processed, the return value of the function is 0 and *tptrp points to
 * the 8-bit option type field (which is followed by the 8-bit option
 * data length, followed by the option data).  If no more options remain
 * to be processed, the return value is -1 and *tptrp is NULL.  If an
 * error occurs, the return value is -1 and *tptrp is not NULL.
 * (RFC 2292, 6.3.5)
 */
int
inet6_option_next(cmsg, tptrp)
	const struct cmsghdr *cmsg;
	u_int8_t **tptrp;
{
	struct ip6_ext *ip6e;
	int hdrlen, optlen;
	u_int8_t *lim;

	if (cmsg->cmsg_level != IPPROTO_IPV6 ||
	    (cmsg->cmsg_type != IPV6_HOPOPTS &&
	     cmsg->cmsg_type != IPV6_DSTOPTS))
		return(-1);

	/* message length validation */
	if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
		return(-1);
	ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
	hdrlen = (ip6e->ip6e_len + 1) << 3;
	if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
		return(-1);

	/*
	 * If the caller does not specify the starting point,
	 * simply return the 1st option.
	 * Otherwise, search the option list for the next option.
	 */
	lim = (u_int8_t *)ip6e + hdrlen;
	if (*tptrp == NULL)
		*tptrp = (u_int8_t *)(ip6e + 1);
	else {
		if ((optlen = ip6optlen(*tptrp, lim)) == 0)
			return(-1);

		*tptrp = *tptrp + optlen;
	}
	if (*tptrp >= lim) {	/* there is no option */
		*tptrp = NULL;
		return(-1);
	}
	/*
	 * Finally, checks if the next option is safely stored in the
	 * cmsg data.
	 */
	if (ip6optlen(*tptrp, lim) == 0)
		return(-1);
	else
		return(0);
}

/*
 * This function is similar to the inet6_option_next() function,
 * except this function lets the caller specify the option type to be
 * searched for, instead of always returning the next option in the
 * ancillary data object.
 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
 *       it's a typo. The variable should be type of u_int8_t **.
 */
int
inet6_option_find(cmsg, tptrp, type)
	const struct cmsghdr *cmsg;
	u_int8_t **tptrp;
	int type;
{
	struct ip6_ext *ip6e;
	int hdrlen, optlen;
	u_int8_t *optp, *lim;

	if (cmsg->cmsg_level != IPPROTO_IPV6 ||
	    (cmsg->cmsg_type != IPV6_HOPOPTS &&
	     cmsg->cmsg_type != IPV6_DSTOPTS))
		return(-1);

	/* message length validation */
	if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
		return(-1);
	ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
	hdrlen = (ip6e->ip6e_len + 1) << 3;
	if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
		return(-1);	

	/*
	 * If the caller does not specify the starting point,
	 * search from the beginning of the option list.
	 * Otherwise, search from *the next option* of the specified point.
	 */
	lim = (u_int8_t *)ip6e + hdrlen;
	if (*tptrp == NULL)
		*tptrp = (u_int8_t *)(ip6e + 1);
	else {
		if ((optlen = ip6optlen(*tptrp, lim)) == 0)
			return(-1);

		*tptrp = *tptrp + optlen;
	}
	for (optp = *tptrp; optp < lim; optp += optlen) {
		if (*optp == type) {
			*tptrp = optp;
			return(0);
		}
		if ((optlen = ip6optlen(optp, lim)) == 0)
			return(-1);
	}

	/* search failed */
	*tptrp = NULL;
	return(-1);
}

/*
 * Calculate the length of a given IPv6 option. Also checks
 * if the option is safely stored in user's buffer according to the
 * calculated length and the limitation of the buffer.
 */
static int
ip6optlen(opt, lim)
	u_int8_t *opt, *lim;
{
	int optlen;

	if (*opt == IP6OPT_PAD1)
		optlen = 1;
	else {
		/* is there enough space to store type and len? */
		if (opt + 2 > lim)
			return(0);
		optlen = *(opt + 1) + 2;
	}
	if (opt + optlen <= lim)
		return(optlen);

	return(0);
}

static void
inet6_insert_padopt(u_char *p, int len)
{
	switch(len) {
	 case 0:
		 return;
	 case 1:
		 p[0] = IP6OPT_PAD1;
		 return;
	 default:
		 p[0] = IP6OPT_PADN;
		 p[1] = len - 2; 
		 memset(&p[2], 0, len - 2);
		 return;
	}
}
Commit	Line	Data
3b7c7bd7 A	1	/*
	2	* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. Neither the name of the project nor the names of its contributors
	14	* may be used to endorse or promote products derived from this software
	15	* without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	20	* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	21	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	22	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	23	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	24	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	25	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	26	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	27	* SUCH DAMAGE.
	28	*
	29	* $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.1 1999/12/16 18:32:01 shin Exp $
	30	*/
	31
	32	#include <sys/param.h>
	33	#include <sys/types.h>
	34	#include <sys/socket.h>
	35
	36	#include <netinet/in.h>
	37	#include <netinet/ip6.h>
	38
	39	#include <string.h>
	40	#include <stdio.h>
	41
	42	static int ip6optlen(u_int8_t opt, u_int8_t lim);
	43	static void inet6_insert_padopt(u_char *p, int len);
	44
	45	/*
	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.
	53	*/
	54	int
	55	inet6_option_space(nbytes)
	56	int nbytes;
	57	{
	58	nbytes += 2; /* we need space for nxt-hdr and length fields */
	59	return(CMSG_SPACE((nbytes + 7) & ~7));
	60	}
	61
	62	/*
	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.
66	*/
67	int
68	inet6_option_init(bp, cmsgp, type)
69	void *bp;
70	struct cmsghdr **cmsgp;
71	int type;
72	{
73	register struct cmsghdr ch = (struct cmsghdr )bp;
74
75	/* argument validation */
76	if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
77	return(-1);
78
79	ch->cmsg_level = IPPROTO_IPV6;
80	ch->cmsg_type = type;
81	ch->cmsg_len = CMSG_LEN(0);
82
83	*cmsgp = ch;
84	return(0);
85	}
86
87	/*
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
91	* an error.
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.
96	*/
97	int
98	inet6_option_append(cmsg, typep, multx, plusy)
99	struct cmsghdr *cmsg;
100	const u_int8_t *typep;
101	int multx;
102	int plusy;
103	{
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);
107
108	/* argument validation */
109	if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
110	return(-1);
111	if (plusy < 0 \|\| plusy > 7)
112	return(-1);
113	if (typep[0] > 255)
114	return(-1);
115
116	/*
117	* If this is the first option, allocate space for the
118	* first 2 bytes(for next header and length fields) of
119	* the option header.
120	*/
121	if (bp == (u_char *)eh) {
122	bp += 2;
123	cmsg->cmsg_len += 2;
124	}
125
126	/* calculate pad length before the option. */
127	off = bp - (u_char *)eh;
128	padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
129	(off % multx);
130	padlen += plusy;
131	/* insert padding */
132	inet6_insert_padopt(bp, padlen);
133	cmsg->cmsg_len += padlen;
134	bp += padlen;
135
136	/* copy the option */
137	if (typep[0] == IP6OPT_PAD1)
138	optlen = 1;
139	else
140	optlen = typep[1] + 2;
141	memcpy(bp, typep, optlen);
142	bp += optlen;
143	cmsg->cmsg_len += optlen;
144
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);
149	bp += padlen;
150	cmsg->cmsg_len += padlen;
151
152	/* update the length field of the ip6 option header */
153	eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
154
155	return(0);
156	}
157
158	/*
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
163	* error.
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.
169	*
170	*/
171	u_int8_t *
172	inet6_option_alloc(cmsg, datalen, multx, plusy)
173	struct cmsghdr *cmsg;
174	int datalen;
175	int multx;
176	int plusy;
177	{
178	int padlen, off;
179	register u_int8_t bp = (u_char )cmsg + cmsg->cmsg_len;
180	u_int8_t *retval;
181	struct ip6_ext eh = (struct ip6_ext )CMSG_DATA(cmsg);
182
183	/* argument validation */
184	if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
185	return(NULL);
186	if (plusy < 0 \|\| plusy > 7)
187	return(NULL);
188
189	/*
190	* If this is the first option, allocate space for the
191	* first 2 bytes(for next header and length fields) of
192	* the option header.
193	*/
194	if (bp == (u_char *)eh) {
195	bp += 2;
196	cmsg->cmsg_len += 2;
197	}
198
199	/* calculate pad length before the option. */
200	off = bp - (u_char *)eh;
201	padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
202	(off % multx);
203	padlen += plusy;
204	/* insert padding */
205	inet6_insert_padopt(bp, padlen);
206	cmsg->cmsg_len += padlen;
207	bp += padlen;
208
209	/* keep space to store specified length of data */
210	retval = bp;
211	bp += datalen;
212	cmsg->cmsg_len += datalen;
213
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);
218	bp += padlen;
219	cmsg->cmsg_len += padlen;
220
221	/* update the length field of the ip6 option header */
222	eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
223
224	return(retval);
225	}
226
227	/*
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.
235	* (RFC 2292, 6.3.5)
236	*/
237	int
238	inet6_option_next(cmsg, tptrp)
239	const struct cmsghdr *cmsg;
240	u_int8_t **tptrp;
241	{
242	struct ip6_ext *ip6e;
243	int hdrlen, optlen;
244	u_int8_t *lim;
245
246	if (cmsg->cmsg_level != IPPROTO_IPV6 \|\|
247	(cmsg->cmsg_type != IPV6_HOPOPTS &&
248	cmsg->cmsg_type != IPV6_DSTOPTS))
249	return(-1);
250
251	/* message length validation */
252	if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
253	return(-1);
254	ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
255	hdrlen = (ip6e->ip6e_len + 1) << 3;
256	if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
257	return(-1);
258
259	/*
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.
263	*/
264	lim = (u_int8_t *)ip6e + hdrlen;
265	if (*tptrp == NULL)
266	tptrp = (u_int8_t )(ip6e + 1);
267	else {
268	if ((optlen = ip6optlen(*tptrp, lim)) == 0)
269	return(-1);
270
271	tptrp = tptrp + optlen;
272	}
273	if (tptrp >= lim) { / there is no option */
274	*tptrp = NULL;
275	return(-1);
276	}
277	/*
278	* Finally, checks if the next option is safely stored in the
279	* cmsg data.
280	*/
281	if (ip6optlen(*tptrp, lim) == 0)
282	return(-1);
283	else
284	return(0);
285	}
286
287	/*
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 **.
294	*/
295	int
296	inet6_option_find(cmsg, tptrp, type)
297	const struct cmsghdr *cmsg;
298	u_int8_t **tptrp;
299	int type;
300	{
301	struct ip6_ext *ip6e;
302	int hdrlen, optlen;
303	u_int8_t optp, lim;
304
305	if (cmsg->cmsg_level != IPPROTO_IPV6 \|\|
306	(cmsg->cmsg_type != IPV6_HOPOPTS &&
307	cmsg->cmsg_type != IPV6_DSTOPTS))
308	return(-1);
309
310	/* message length validation */
311	if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
312	return(-1);
313	ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
314	hdrlen = (ip6e->ip6e_len + 1) << 3;
315	if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
316	return(-1);
317
318	/*
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.
322	*/
323	lim = (u_int8_t *)ip6e + hdrlen;
324	if (*tptrp == NULL)
325	tptrp = (u_int8_t )(ip6e + 1);
326	else {
327	if ((optlen = ip6optlen(*tptrp, lim)) == 0)
328	return(-1);
329
330	tptrp = tptrp + optlen;
331	}
332	for (optp = *tptrp; optp < lim; optp += optlen) {
333	if (*optp == type) {
334	*tptrp = optp;
335	return(0);
336	}
337	if ((optlen = ip6optlen(optp, lim)) == 0)
338	return(-1);
339	}
340
341	/* search failed */
342	*tptrp = NULL;
343	return(-1);
344	}
345
346	/*
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.
350	*/
351	static int
352	ip6optlen(opt, lim)
353	u_int8_t opt, lim;
354	{
355	int optlen;
356
357	if (*opt == IP6OPT_PAD1)
358	optlen = 1;
359	else {
360	/* is there enough space to store type and len? */
361	if (opt + 2 > lim)
362	return(0);
363	optlen = *(opt + 1) + 2;
364	}
365	if (opt + optlen <= lim)
366	return(optlen);
367
368	return(0);
369	}
370
371	static void
372	inet6_insert_padopt(u_char *p, int len)
373	{
374	switch(len) {
375	case 0:
376	return;
377	case 1:
378	p[0] = IP6OPT_PAD1;
379	return;
380	default:
381	p[0] = IP6OPT_PADN;
382	p[1] = len - 2;
383	memset(&p[2], 0, len - 2);
384	return;
385	}
386	}