1 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */
2
3 /*
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: stable/9/lib/libc/net/ip6opt.c 242544 2012-11-04 01:21:49Z eadler $");
34
35 #include <sys/param.h>
36 #include <sys/types.h>
37 #include <sys/socket.h>
38
39 #include <netinet/in.h>
40 #include <netinet/ip6.h>
41
42 #include <string.h>
43 #include <stdio.h>
44
45 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
46 static void inet6_insert_padopt(u_char *p, int len);
47
48 /*
49 * This function returns the number of bytes required to hold an option
50 * when it is stored as ancillary data, including the cmsghdr structure
51 * at the beginning, and any padding at the end (to make its size a
52 * multiple of 8 bytes). The argument is the size of the structure
53 * defining the option, which must include any pad bytes at the
54 * beginning (the value y in the alignment term "xn + y"), the type
55 * byte, the length byte, and the option data.
56 */
57 int
inet6_option_space(int nbytes)58 inet6_option_space(int nbytes)
59 {
60 nbytes += 2; /* we need space for nxt-hdr and length fields */
61 return(CMSG_SPACE((nbytes + 7) & ~7));
62 }
63
64 /*
65 * This function is called once per ancillary data object that will
66 * contain either Hop-by-Hop or Destination options. It returns 0 on
67 * success or -1 on an error.
68 */
69 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)70 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
71 {
72 struct cmsghdr *ch = (struct cmsghdr *)bp;
73
74 /* argument validation */
75 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
76 return(-1);
77
78 ch->cmsg_level = IPPROTO_IPV6;
79 ch->cmsg_type = type;
80 ch->cmsg_len = CMSG_LEN(0);
81
82 *cmsgp = ch;
83 return(0);
84 }
85
86 /*
87 * This function appends a Hop-by-Hop option or a Destination option
88 * into an ancillary data object that has been initialized by
89 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
90 * an error.
91 * multx is the value x in the alignment term "xn + y" described
92 * earlier. It must have a value of 1, 2, 4, or 8.
93 * plusy is the value y in the alignment term "xn + y" described
94 * earlier. It must have a value between 0 and 7, inclusive.
95 */
96 int
inet6_option_append(struct cmsghdr * cmsg,const u_int8_t * typep,int multx,int plusy)97 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
98 int plusy)
99 {
100 int padlen, optlen, off;
101 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
102 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
103
104 /* argument validation */
105 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
106 return(-1);
107 if (plusy < 0 || plusy > 7)
108 return(-1);
109
110 /*
111 * If this is the first option, allocate space for the
112 * first 2 bytes(for next header and length fields) of
113 * the option header.
114 */
115 if (bp == (u_char *)eh) {
116 bp += 2;
117 cmsg->cmsg_len += 2;
118 }
119
120 /* calculate pad length before the option. */
121 off = bp - (u_char *)eh;
122 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
123 (off % multx);
124 padlen += plusy;
125 padlen %= multx; /* keep the pad as short as possible */
126 /* insert padding */
127 inet6_insert_padopt(bp, padlen);
128 cmsg->cmsg_len += padlen;
129 bp += padlen;
130
131 /* copy the option */
132 if (typep[0] == IP6OPT_PAD1)
133 optlen = 1;
134 else
135 optlen = typep[1] + 2;
136 memcpy(bp, typep, optlen);
137 bp += optlen;
138 cmsg->cmsg_len += optlen;
139
140 /* calculate pad length after the option and insert the padding */
141 off = bp - (u_char *)eh;
142 padlen = ((off + 7) & ~7) - off;
143 inet6_insert_padopt(bp, padlen);
144 bp += padlen;
145 cmsg->cmsg_len += padlen;
146
147 /* update the length field of the ip6 option header */
148 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
149
150 return(0);
151 }
152
153 /*
154 * This function appends a Hop-by-Hop option or a Destination option
155 * into an ancillary data object that has been initialized by
156 * inet6_option_init(). This function returns a pointer to the 8-bit
157 * option type field that starts the option on success, or NULL on an
158 * error.
159 * The difference between this function and inet6_option_append() is
160 * that the latter copies the contents of a previously built option into
161 * the ancillary data object while the current function returns a
162 * pointer to the space in the data object where the option's TLV must
163 * then be built by the caller.
164 *
165 */
166 u_int8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)167 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
168 {
169 int padlen, off;
170 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
171 u_int8_t *retval;
172 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
173
174 /* argument validation */
175 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
176 return(NULL);
177 if (plusy < 0 || plusy > 7)
178 return(NULL);
179
180 /*
181 * If this is the first option, allocate space for the
182 * first 2 bytes(for next header and length fields) of
183 * the option header.
184 */
185 if (bp == (u_char *)eh) {
186 bp += 2;
187 cmsg->cmsg_len += 2;
188 }
189
190 /* calculate pad length before the option. */
191 off = bp - (u_char *)eh;
192 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
193 (off % multx);
194 padlen += plusy;
195 padlen %= multx; /* keep the pad as short as possible */
196 /* insert padding */
197 inet6_insert_padopt(bp, padlen);
198 cmsg->cmsg_len += padlen;
199 bp += padlen;
200
201 /* keep space to store specified length of data */
202 retval = bp;
203 bp += datalen;
204 cmsg->cmsg_len += datalen;
205
206 /* calculate pad length after the option and insert the padding */
207 off = bp - (u_char *)eh;
208 padlen = ((off + 7) & ~7) - off;
209 inet6_insert_padopt(bp, padlen);
210 bp += padlen;
211 cmsg->cmsg_len += padlen;
212
213 /* update the length field of the ip6 option header */
214 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
215
216 return(retval);
217 }
218
219 /*
220 * This function processes the next Hop-by-Hop option or Destination
221 * option in an ancillary data object. If another option remains to be
222 * processed, the return value of the function is 0 and *tptrp points to
223 * the 8-bit option type field (which is followed by the 8-bit option
224 * data length, followed by the option data). If no more options remain
225 * to be processed, the return value is -1 and *tptrp is NULL. If an
226 * error occurs, the return value is -1 and *tptrp is not NULL.
227 * (RFC 2292, 6.3.5)
228 */
229 int
inet6_option_next(const struct cmsghdr * cmsg,u_int8_t ** tptrp)230 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
231 {
232 struct ip6_ext *ip6e;
233 int hdrlen, optlen;
234 u_int8_t *lim;
235
236 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
237 (cmsg->cmsg_type != IPV6_HOPOPTS &&
238 cmsg->cmsg_type != IPV6_DSTOPTS))
239 return(-1);
240
241 /* message length validation */
242 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
243 return(-1);
244 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
245 hdrlen = (ip6e->ip6e_len + 1) << 3;
246 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
247 return(-1);
248
249 /*
250 * If the caller does not specify the starting point,
251 * simply return the 1st option.
252 * Otherwise, search the option list for the next option.
253 */
254 lim = (u_int8_t *)ip6e + hdrlen;
255 if (*tptrp == NULL)
256 *tptrp = (u_int8_t *)(ip6e + 1);
257 else {
258 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
259 return(-1);
260
261 *tptrp = *tptrp + optlen;
262 }
263 if (*tptrp >= lim) { /* there is no option */
264 *tptrp = NULL;
265 return(-1);
266 }
267 /*
268 * Finally, checks if the next option is safely stored in the
269 * cmsg data.
270 */
271 if (ip6optlen(*tptrp, lim) == 0)
272 return(-1);
273 else
274 return(0);
275 }
276
277 /*
278 * This function is similar to the inet6_option_next() function,
279 * except this function lets the caller specify the option type to be
280 * searched for, instead of always returning the next option in the
281 * ancillary data object.
282 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
283 * it's a typo. The variable should be type of u_int8_t **.
284 */
285 int
inet6_option_find(const struct cmsghdr * cmsg,u_int8_t ** tptrp,int type)286 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
287 {
288 struct ip6_ext *ip6e;
289 int hdrlen, optlen;
290 u_int8_t *optp, *lim;
291
292 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
293 (cmsg->cmsg_type != IPV6_HOPOPTS &&
294 cmsg->cmsg_type != IPV6_DSTOPTS))
295 return(-1);
296
297 /* message length validation */
298 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
299 return(-1);
300 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
301 hdrlen = (ip6e->ip6e_len + 1) << 3;
302 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
303 return(-1);
304
305 /*
306 * If the caller does not specify the starting point,
307 * search from the beginning of the option list.
308 * Otherwise, search from *the next option* of the specified point.
309 */
310 lim = (u_int8_t *)ip6e + hdrlen;
311 if (*tptrp == NULL)
312 *tptrp = (u_int8_t *)(ip6e + 1);
313 else {
314 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
315 return(-1);
316
317 *tptrp = *tptrp + optlen;
318 }
319 for (optp = *tptrp; optp < lim; optp += optlen) {
320 if (*optp == type) {
321 *tptrp = optp;
322 return(0);
323 }
324 if ((optlen = ip6optlen(optp, lim)) == 0)
325 return(-1);
326 }
327
328 /* search failed */
329 *tptrp = NULL;
330 return(-1);
331 }
332
333 /*
334 * Calculate the length of a given IPv6 option. Also checks
335 * if the option is safely stored in user's buffer according to the
336 * calculated length and the limitation of the buffer.
337 */
338 static int
ip6optlen(u_int8_t * opt,u_int8_t * lim)339 ip6optlen(u_int8_t *opt, u_int8_t *lim)
340 {
341 int optlen;
342
343 if (*opt == IP6OPT_PAD1)
344 optlen = 1;
345 else {
346 /* is there enough space to store type and len? */
347 if (opt + 2 > lim)
348 return(0);
349 optlen = *(opt + 1) + 2;
350 }
351 if (opt + optlen <= lim)
352 return(optlen);
353
354 return(0);
355 }
356
357 static void
inet6_insert_padopt(u_char * p,int len)358 inet6_insert_padopt(u_char *p, int len)
359 {
360 switch(len) {
361 case 0:
362 return;
363 case 1:
364 p[0] = IP6OPT_PAD1;
365 return;
366 default:
367 p[0] = IP6OPT_PADN;
368 p[1] = len - 2;
369 memset(&p[2], 0, len - 2);
370 return;
371 }
372 }
373
374 /*
375 * The following functions are defined in RFC3542, which is a successor
376 * of RFC2292.
377 */
378
379 int
inet6_opt_init(void * extbuf,socklen_t extlen)380 inet6_opt_init(void *extbuf, socklen_t extlen)
381 {
382 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
383
384 if (extlen < 0 || (extlen % 8))
385 return(-1);
386
387 if (ext) {
388 if (extlen == 0)
389 return(-1);
390 ext->ip6e_len = (extlen >> 3) - 1;
391 }
392
393 return(2); /* sizeof the next and the length fields */
394 }
395
396 int
inet6_opt_append(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t len,u_int8_t align,void ** databufp)397 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
398 socklen_t len, u_int8_t align, void **databufp)
399 {
400 int currentlen = offset, padlen = 0;
401
402 /*
403 * The option type must have a value from 2 to 255, inclusive.
404 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
405 */
406 if (type < 2)
407 return(-1);
408
409 /*
410 * The option data length must have a value between 0 and 255,
411 * inclusive, and is the length of the option data that follows.
412 */
413 if (len < 0 || len > 255)
414 return(-1);
415
416 /*
417 * The align parameter must have a value of 1, 2, 4, or 8.
418 * The align value can not exceed the value of len.
419 */
420 if (align != 1 && align != 2 && align != 4 && align != 8)
421 return(-1);
422 if (align > len)
423 return(-1);
424
425 /* Calculate the padding length. */
426 currentlen += 2 + len; /* 2 means "type + len" */
427 if (currentlen % align)
428 padlen = align - (currentlen % align);
429
430 /* The option must fit in the extension header buffer. */
431 currentlen += padlen;
432 if (extlen && /* XXX: right? */
433 currentlen > extlen)
434 return(-1);
435
436 if (extbuf) {
437 u_int8_t *optp = (u_int8_t *)extbuf + offset;
438
439 if (padlen == 1) {
440 /* insert a Pad1 option */
441 *optp = IP6OPT_PAD1;
442 optp++;
443 }
444 else if (padlen > 0) {
445 /* insert a PadN option for alignment */
446 *optp++ = IP6OPT_PADN;
447 *optp++ = padlen - 2;
448 memset(optp, 0, padlen - 2);
449 optp += (padlen - 2);
450 }
451
452 *optp++ = type;
453 *optp++ = len;
454
455 *databufp = optp;
456 }
457
458 return(currentlen);
459 }
460
461 int
inet6_opt_finish(void * extbuf,socklen_t extlen,int offset)462 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
463 {
464 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
465
466 if (extbuf) {
467 u_int8_t *padp;
468 int padlen = updatelen - offset;
469
470 if (updatelen > extlen)
471 return(-1);
472
473 padp = (u_int8_t *)extbuf + offset;
474 if (padlen == 1)
475 *padp = IP6OPT_PAD1;
476 else if (padlen > 0) {
477 *padp++ = IP6OPT_PADN;
478 *padp++ = (padlen - 2);
479 memset(padp, 0, padlen - 2);
480 }
481 }
482
483 return(updatelen);
484 }
485
486 int
inet6_opt_set_val(void * databuf,int offset,void * val,socklen_t vallen)487 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
488 {
489
490 memcpy((u_int8_t *)databuf + offset, val, vallen);
491 return(offset + vallen);
492 }
493
494 int
inet6_opt_next(void * extbuf,socklen_t extlen,int offset,u_int8_t * typep,socklen_t * lenp,void ** databufp)495 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
496 socklen_t *lenp, void **databufp)
497 {
498 u_int8_t *optp, *lim;
499 int optlen;
500
501 /* Validate extlen. XXX: is the variable really necessary?? */
502 if (extlen == 0 || (extlen % 8))
503 return(-1);
504 lim = (u_int8_t *)extbuf + extlen;
505
506 /*
507 * If this is the first time this function called for this options
508 * header, simply return the 1st option.
509 * Otherwise, search the option list for the next option.
510 */
511 if (offset == 0) {
512 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
513 }
514 else
515 optp = (u_int8_t *)extbuf + offset;
516
517 /* Find the next option skipping any padding options. */
518 while(optp < lim) {
519 switch(*optp) {
520 case IP6OPT_PAD1:
521 optp++;
522 break;
523 case IP6OPT_PADN:
524 if ((optlen = ip6optlen(optp, lim)) == 0)
525 goto optend;
526 optp += optlen;
527 break;
528 default: /* found */
529 if ((optlen = ip6optlen(optp, lim)) == 0)
530 goto optend;
531 *typep = *optp;
532 *lenp = optlen - 2;
533 *databufp = optp + 2;
534 return(optp + optlen - (u_int8_t *)extbuf);
535 }
536 }
537
538 optend:
539 *databufp = NULL; /* for safety */
540 return(-1);
541 }
542
543 int
inet6_opt_find(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t * lenp,void ** databufp)544 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
545 socklen_t *lenp, void **databufp)
546 {
547 u_int8_t *optp, *lim;
548 int optlen;
549
550 /* Validate extlen. XXX: is the variable really necessary?? */
551 if (extlen == 0 || (extlen % 8))
552 return(-1);
553 lim = (u_int8_t *)extbuf + extlen;
554
555 /*
556 * If this is the first time this function called for this options
557 * header, simply return the 1st option.
558 * Otherwise, search the option list for the next option.
559 */
560 if (offset == 0) {
561 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
562 }
563 else
564 optp = (u_int8_t *)extbuf + offset;
565
566 /* Find the specified option */
567 while(optp < lim) {
568 if ((optlen = ip6optlen(optp, lim)) == 0)
569 goto optend;
570
571 if (*optp == type) { /* found */
572 *lenp = optlen - 2;
573 *databufp = optp + 2;
574 return(optp + optlen - (u_int8_t *)extbuf);
575 }
576
577 optp += optlen;
578 }
579
580 optend:
581 *databufp = NULL; /* for safety */
582 return(-1);
583 }
584
585 int
inet6_opt_get_val(void * databuf,int offset,void * val,socklen_t vallen)586 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
587 {
588
589 /* we can't assume alignment here */
590 memcpy(val, (u_int8_t *)databuf + offset, vallen);
591
592 return(offset + vallen);
593 }
594