1 /** $MirOS: src/lib/libc/net/ip6opt.c,v 1.3 2005/07/09 13:23:32 tg Exp $ */
2 /* $OpenBSD: ip6opt.c,v 1.2 2005/03/25 13:24:12 otto Exp $ */
3
4 /*
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the project nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <sys/param.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
inet6_option_space(int nbytes)55 inet6_option_space(int nbytes)
56 {
57 nbytes += 2; /* we need space for nxt-hdr and length fields */
58 return(CMSG_SPACE((nbytes + 7) & ~7));
59 }
60
61 /*
62 * This function is called once per ancillary data object that will
63 * contain either Hop-by-Hop or Destination options. It returns 0 on
64 * success or -1 on an error.
65 */
66 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)67 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
68 {
69 struct cmsghdr *ch = (struct cmsghdr *)bp;
70
71 /* argument validation */
72 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
73 return(-1);
74
75 ch->cmsg_level = IPPROTO_IPV6;
76 ch->cmsg_type = type;
77 ch->cmsg_len = CMSG_LEN(0);
78
79 *cmsgp = ch;
80 return(0);
81 }
82
83 /*
84 * This function appends a Hop-by-Hop option or a Destination option
85 * into an ancillary data object that has been initialized by
86 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
87 * an error.
88 * multx is the value x in the alignment term "xn + y" described
89 * earlier. It must have a value of 1, 2, 4, or 8.
90 * plusy is the value y in the alignment term "xn + y" described
91 * earlier. It must have a value between 0 and 7, inclusive.
92 */
93 int
inet6_option_append(struct cmsghdr * cmsg,const u_int8_t * typep,int multx,int plusy)94 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
95 int plusy)
96 {
97 int padlen, optlen, off;
98 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
99 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
100
101 /* argument validation */
102 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
103 return(-1);
104 if (plusy < 0 || plusy > 7)
105 return(-1);
106 #if 0
107 if (typep[0] > 255)
108 return(-1);
109 #endif
110
111 /*
112 * If this is the first option, allocate space for the
113 * first 2 bytes(for next header and length fields) of
114 * the option header.
115 */
116 if (bp == (u_char *)eh) {
117 bp += 2;
118 cmsg->cmsg_len += 2;
119 }
120
121 /* calculate pad length before the option. */
122 off = bp - (u_char *)eh;
123 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
124 (off % multx);
125 padlen += plusy;
126 padlen %= multx; /* keep the pad as short as possible */
127 /* insert padding */
128 inet6_insert_padopt(bp, padlen);
129 cmsg->cmsg_len += padlen;
130 bp += padlen;
131
132 /* copy the option */
133 if (typep[0] == IP6OPT_PAD1)
134 optlen = 1;
135 else
136 optlen = typep[1] + 2;
137 memcpy(bp, typep, optlen);
138 bp += optlen;
139 cmsg->cmsg_len += optlen;
140
141 /* calculate pad length after the option and insert the padding */
142 off = bp - (u_char *)eh;
143 padlen = ((off + 7) & ~7) - off;
144 inet6_insert_padopt(bp, padlen);
145 bp += padlen;
146 cmsg->cmsg_len += padlen;
147
148 /* update the length field of the ip6 option header */
149 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
150
151 return(0);
152 }
153
154 /*
155 * This function appends a Hop-by-Hop option or a Destination option
156 * into an ancillary data object that has been initialized by
157 * inet6_option_init(). This function returns a pointer to the 8-bit
158 * option type field that starts the option on success, or NULL on an
159 * error.
160 * The difference between this function and inet6_option_append() is
161 * that the latter copies the contents of a previously built option into
162 * the ancillary data object while the current function returns a
163 * pointer to the space in the data object where the option's TLV must
164 * then be built by the caller.
165 *
166 */
167 u_int8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)168 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
169 {
170 int padlen, off;
171 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
172 u_int8_t *retval;
173 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
174
175 /* argument validation */
176 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
177 return(NULL);
178 if (plusy < 0 || plusy > 7)
179 return(NULL);
180
181 /*
182 * If this is the first option, allocate space for the
183 * first 2 bytes(for next header and length fields) of
184 * the option header.
185 */
186 if (bp == (u_char *)eh) {
187 bp += 2;
188 cmsg->cmsg_len += 2;
189 }
190
191 /* calculate pad length before the option. */
192 off = bp - (u_char *)eh;
193 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
194 (off % multx);
195 padlen += plusy;
196 padlen %= multx; /* keep the pad as short as possible */
197 /* insert padding */
198 inet6_insert_padopt(bp, padlen);
199 cmsg->cmsg_len += padlen;
200 bp += padlen;
201
202 /* keep space to store specified length of data */
203 retval = bp;
204 bp += datalen;
205 cmsg->cmsg_len += datalen;
206
207 /* calculate pad length after the option and insert the padding */
208 off = bp - (u_char *)eh;
209 padlen = ((off + 7) & ~7) - off;
210 inet6_insert_padopt(bp, padlen);
211 bp += padlen;
212 cmsg->cmsg_len += padlen;
213
214 /* update the length field of the ip6 option header */
215 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
216
217 return(retval);
218 }
219
220 /*
221 * This function processes the next Hop-by-Hop option or Destination
222 * option in an ancillary data object. If another option remains to be
223 * processed, the return value of the function is 0 and *tptrp points to
224 * the 8-bit option type field (which is followed by the 8-bit option
225 * data length, followed by the option data). If no more options remain
226 * to be processed, the return value is -1 and *tptrp is NULL. If an
227 * error occurs, the return value is -1 and *tptrp is not NULL.
228 * (RFC 2292, 6.3.5)
229 */
230 int
inet6_option_next(const struct cmsghdr * cmsg,u_int8_t ** tptrp)231 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
232 {
233 struct ip6_ext *ip6e;
234 int hdrlen, optlen;
235 u_int8_t *lim;
236
237 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
238 (cmsg->cmsg_type != IPV6_HOPOPTS &&
239 cmsg->cmsg_type != IPV6_DSTOPTS))
240 return(-1);
241
242 /* message length validation */
243 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
244 return(-1);
245 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
246 hdrlen = (ip6e->ip6e_len + 1) << 3;
247 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
248 return(-1);
249
250 /*
251 * If the caller does not specify the starting point,
252 * simply return the 1st option.
253 * Otherwise, search the option list for the next option.
254 */
255 lim = (u_int8_t *)ip6e + hdrlen;
256 if (*tptrp == NULL)
257 *tptrp = (u_int8_t *)(ip6e + 1);
258 else {
259 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
260 return(-1);
261
262 *tptrp = *tptrp + optlen;
263 }
264 if (*tptrp >= lim) { /* there is no option */
265 *tptrp = NULL;
266 return(-1);
267 }
268 /*
269 * Finally, checks if the next option is safely stored in the
270 * cmsg data.
271 */
272 if (ip6optlen(*tptrp, lim) == 0)
273 return(-1);
274 else
275 return(0);
276 }
277
278 /*
279 * This function is similar to the inet6_option_next() function,
280 * except this function lets the caller specify the option type to be
281 * searched for, instead of always returning the next option in the
282 * ancillary data object.
283 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
284 * it's a typo. The variable should be type of u_int8_t **.
285 */
286 int
inet6_option_find(const struct cmsghdr * cmsg,u_int8_t ** tptrp,int type)287 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
288 {
289 struct ip6_ext *ip6e;
290 int hdrlen, optlen;
291 u_int8_t *optp, *lim;
292
293 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
294 (cmsg->cmsg_type != IPV6_HOPOPTS &&
295 cmsg->cmsg_type != IPV6_DSTOPTS))
296 return(-1);
297
298 /* message length validation */
299 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
300 return(-1);
301 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
302 hdrlen = (ip6e->ip6e_len + 1) << 3;
303 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
304 return(-1);
305
306 /*
307 * If the caller does not specify the starting point,
308 * search from the beginning of the option list.
309 * Otherwise, search from *the next option* of the specified point.
310 */
311 lim = (u_int8_t *)ip6e + hdrlen;
312 if (*tptrp == NULL)
313 *tptrp = (u_int8_t *)(ip6e + 1);
314 else {
315 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
316 return(-1);
317
318 *tptrp = *tptrp + optlen;
319 }
320 for (optp = *tptrp; optp < lim; optp += optlen) {
321 if (*optp == type) {
322 *tptrp = optp;
323 return(0);
324 }
325 if ((optlen = ip6optlen(optp, lim)) == 0)
326 return(-1);
327 }
328
329 /* search failed */
330 *tptrp = NULL;
331 return(-1);
332 }
333
334 /*
335 * Calculate the length of a given IPv6 option. Also checks
336 * if the option is safely stored in user's buffer according to the
337 * calculated length and the limitation of the buffer.
338 */
339 static int
ip6optlen(u_int8_t * opt,u_int8_t * lim)340 ip6optlen(u_int8_t *opt, u_int8_t *lim)
341 {
342 int optlen;
343
344 if (*opt == IP6OPT_PAD1)
345 optlen = 1;
346 else {
347 /* is there enough space to store type and len? */
348 if (opt + 2 > lim)
349 return(0);
350 optlen = *(opt + 1) + 2;
351 }
352 if (opt + optlen <= lim)
353 return(optlen);
354
355 return(0);
356 }
357
358 static void
inet6_insert_padopt(u_char * p,int len)359 inet6_insert_padopt(u_char *p, int len)
360 {
361 switch(len) {
362 case 0:
363 return;
364 case 1:
365 p[0] = IP6OPT_PAD1;
366 return;
367 default:
368 p[0] = IP6OPT_PADN;
369 p[1] = len - 2;
370 memset(&p[2], 0, len - 2);
371 return;
372 }
373 }
374