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("$FreeBSD$");
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 #ifndef IPV6_2292HOPOPTS
49 #define IPV6_2292HOPOPTS 22
50 #endif
51 #ifndef IPV6_2292DSTOPTS
52 #define IPV6_2292DSTOPTS 23
53 #endif
54
55 #define is_ipv6_hopopts(x) \
56 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
57 #define is_ipv6_dstopts(x) \
58 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
59
60 /*
61 * This function returns the number of bytes required to hold an option
62 * when it is stored as ancillary data, including the cmsghdr structure
63 * at the beginning, and any padding at the end (to make its size a
64 * multiple of 8 bytes). The argument is the size of the structure
65 * defining the option, which must include any pad bytes at the
66 * beginning (the value y in the alignment term "xn + y"), the type
67 * byte, the length byte, and the option data.
68 */
69 int
inet6_option_space(int nbytes)70 inet6_option_space(int nbytes)
71 {
72 nbytes += 2; /* we need space for nxt-hdr and length fields */
73 return(CMSG_SPACE((nbytes + 7) & ~7));
74 }
75
76 /*
77 * This function is called once per ancillary data object that will
78 * contain either Hop-by-Hop or Destination options. It returns 0 on
79 * success or -1 on an error.
80 */
81 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)82 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
83 {
84 struct cmsghdr *ch = (struct cmsghdr *)bp;
85
86 /* argument validation */
87 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
88 return(-1);
89
90 ch->cmsg_level = IPPROTO_IPV6;
91 ch->cmsg_type = type;
92 ch->cmsg_len = CMSG_LEN(0);
93
94 *cmsgp = ch;
95 return(0);
96 }
97
98 /*
99 * This function appends a Hop-by-Hop option or a Destination option
100 * into an ancillary data object that has been initialized by
101 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
102 * an error.
103 * multx is the value x in the alignment term "xn + y" described
104 * earlier. It must have a value of 1, 2, 4, or 8.
105 * plusy is the value y in the alignment term "xn + y" described
106 * earlier. It must have a value between 0 and 7, inclusive.
107 */
108 int
inet6_option_append(struct cmsghdr * cmsg,const u_int8_t * typep,int multx,int plusy)109 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
110 int plusy)
111 {
112 int padlen, optlen, off;
113 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
114 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
115
116 /* argument validation */
117 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
118 return(-1);
119 if (plusy < 0 || plusy > 7)
120 return(-1);
121
122 /*
123 * If this is the first option, allocate space for the
124 * first 2 bytes(for next header and length fields) of
125 * the option header.
126 */
127 if (bp == (u_char *)eh) {
128 bp += 2;
129 cmsg->cmsg_len += 2;
130 }
131
132 /* calculate pad length before the option. */
133 off = bp - (u_char *)eh;
134 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
135 (off % multx);
136 padlen += plusy;
137 padlen %= multx; /* keep the pad as short as possible */
138 /* insert padding */
139 inet6_insert_padopt(bp, padlen);
140 cmsg->cmsg_len += padlen;
141 bp += padlen;
142
143 /* copy the option */
144 if (typep[0] == IP6OPT_PAD1)
145 optlen = 1;
146 else
147 optlen = typep[1] + 2;
148 memcpy(bp, typep, optlen);
149 bp += optlen;
150 cmsg->cmsg_len += optlen;
151
152 /* calculate pad length after the option and insert the padding */
153 off = bp - (u_char *)eh;
154 padlen = ((off + 7) & ~7) - off;
155 inet6_insert_padopt(bp, padlen);
156 bp += padlen;
157 cmsg->cmsg_len += padlen;
158
159 /* update the length field of the ip6 option header */
160 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
161
162 return(0);
163 }
164
165 /*
166 * This function appends a Hop-by-Hop option or a Destination option
167 * into an ancillary data object that has been initialized by
168 * inet6_option_init(). This function returns a pointer to the 8-bit
169 * option type field that starts the option on success, or NULL on an
170 * error.
171 * The difference between this function and inet6_option_append() is
172 * that the latter copies the contents of a previously built option into
173 * the ancillary data object while the current function returns a
174 * pointer to the space in the data object where the option's TLV must
175 * then be built by the caller.
176 *
177 */
178 u_int8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)179 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
180 {
181 int padlen, off;
182 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
183 u_int8_t *retval;
184 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
185
186 /* argument validation */
187 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
188 return(NULL);
189 if (plusy < 0 || plusy > 7)
190 return(NULL);
191
192 /*
193 * If this is the first option, allocate space for the
194 * first 2 bytes(for next header and length fields) of
195 * the option header.
196 */
197 if (bp == (u_char *)eh) {
198 bp += 2;
199 cmsg->cmsg_len += 2;
200 }
201
202 /* calculate pad length before the option. */
203 off = bp - (u_char *)eh;
204 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
205 (off % multx);
206 padlen += plusy;
207 padlen %= multx; /* keep the pad as short as possible */
208 /* insert padding */
209 inet6_insert_padopt(bp, padlen);
210 cmsg->cmsg_len += padlen;
211 bp += padlen;
212
213 /* keep space to store specified length of data */
214 retval = bp;
215 bp += datalen;
216 cmsg->cmsg_len += datalen;
217
218 /* calculate pad length after the option and insert the padding */
219 off = bp - (u_char *)eh;
220 padlen = ((off + 7) & ~7) - off;
221 inet6_insert_padopt(bp, padlen);
222 bp += padlen;
223 cmsg->cmsg_len += padlen;
224
225 /* update the length field of the ip6 option header */
226 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
227
228 return(retval);
229 }
230
231 /*
232 * This function processes the next Hop-by-Hop option or Destination
233 * option in an ancillary data object. If another option remains to be
234 * processed, the return value of the function is 0 and *tptrp points to
235 * the 8-bit option type field (which is followed by the 8-bit option
236 * data length, followed by the option data). If no more options remain
237 * to be processed, the return value is -1 and *tptrp is NULL. If an
238 * error occurs, the return value is -1 and *tptrp is not NULL.
239 * (RFC 2292, 6.3.5)
240 */
241 int
inet6_option_next(const struct cmsghdr * cmsg,u_int8_t ** tptrp)242 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
243 {
244 struct ip6_ext *ip6e;
245 int hdrlen, optlen;
246 u_int8_t *lim;
247
248 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
249 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
250 !is_ipv6_dstopts(cmsg->cmsg_type)))
251 return(-1);
252
253 /* message length validation */
254 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
255 return(-1);
256 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
257 hdrlen = (ip6e->ip6e_len + 1) << 3;
258 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
259 return(-1);
260
261 /*
262 * If the caller does not specify the starting point,
263 * simply return the 1st option.
264 * Otherwise, search the option list for the next option.
265 */
266 lim = (u_int8_t *)ip6e + hdrlen;
267 if (*tptrp == NULL)
268 *tptrp = (u_int8_t *)(ip6e + 1);
269 else {
270 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
271 return(-1);
272
273 *tptrp = *tptrp + optlen;
274 }
275 if (*tptrp >= lim) { /* there is no option */
276 *tptrp = NULL;
277 return(-1);
278 }
279 /*
280 * Finally, checks if the next option is safely stored in the
281 * cmsg data.
282 */
283 if (ip6optlen(*tptrp, lim) == 0)
284 return(-1);
285 else
286 return(0);
287 }
288
289 /*
290 * This function is similar to the inet6_option_next() function,
291 * except this function lets the caller specify the option type to be
292 * searched for, instead of always returning the next option in the
293 * ancillary data object.
294 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
295 * it's a typo. The variable should be type of u_int8_t **.
296 */
297 int
inet6_option_find(const struct cmsghdr * cmsg,u_int8_t ** tptrp,int type)298 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
299 {
300 struct ip6_ext *ip6e;
301 int hdrlen, optlen;
302 u_int8_t *optp, *lim;
303
304 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
305 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
306 !is_ipv6_dstopts(cmsg->cmsg_type)))
307 return(-1);
308
309 /* message length validation */
310 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
311 return(-1);
312 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
313 hdrlen = (ip6e->ip6e_len + 1) << 3;
314 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
315 return(-1);
316
317 /*
318 * If the caller does not specify the starting point,
319 * search from the beginning of the option list.
320 * Otherwise, search from *the next option* of the specified point.
321 */
322 lim = (u_int8_t *)ip6e + hdrlen;
323 if (*tptrp == NULL)
324 *tptrp = (u_int8_t *)(ip6e + 1);
325 else {
326 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
327 return(-1);
328
329 *tptrp = *tptrp + optlen;
330 }
331 for (optp = *tptrp; optp < lim; optp += optlen) {
332 if (*optp == type) {
333 *tptrp = optp;
334 return(0);
335 }
336 if ((optlen = ip6optlen(optp, lim)) == 0)
337 return(-1);
338 }
339
340 /* search failed */
341 *tptrp = NULL;
342 return(-1);
343 }
344
345 /*
346 * Calculate the length of a given IPv6 option. Also checks
347 * if the option is safely stored in user's buffer according to the
348 * calculated length and the limitation of the buffer.
349 */
350 static int
ip6optlen(u_int8_t * opt,u_int8_t * lim)351 ip6optlen(u_int8_t *opt, u_int8_t *lim)
352 {
353 int optlen;
354
355 if (*opt == IP6OPT_PAD1)
356 optlen = 1;
357 else {
358 /* is there enough space to store type and len? */
359 if (opt + 2 > lim)
360 return(0);
361 optlen = *(opt + 1) + 2;
362 }
363 if (opt + optlen <= lim)
364 return(optlen);
365
366 return(0);
367 }
368
369 static void
inet6_insert_padopt(u_char * p,int len)370 inet6_insert_padopt(u_char *p, int len)
371 {
372 switch(len) {
373 case 0:
374 return;
375 case 1:
376 p[0] = IP6OPT_PAD1;
377 return;
378 default:
379 p[0] = IP6OPT_PADN;
380 p[1] = len - 2;
381 memset(&p[2], 0, len - 2);
382 return;
383 }
384 }
385
386 /*
387 * The following functions are defined in RFC3542, which is a successor
388 * of RFC2292.
389 */
390
391 int
inet6_opt_init(void * extbuf,socklen_t extlen)392 inet6_opt_init(void *extbuf, socklen_t extlen)
393 {
394 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
395
396 if (ext) {
397 if (extlen <= 0 || (extlen % 8))
398 return(-1);
399 ext->ip6e_len = (extlen >> 3) - 1;
400 }
401
402 return(2); /* sizeof the next and the length fields */
403 }
404
405 int
inet6_opt_append(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t len,u_int8_t align,void ** databufp)406 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
407 socklen_t len, u_int8_t align, void **databufp)
408 {
409 int currentlen = offset, padlen = 0;
410
411 /*
412 * The option type must have a value from 2 to 255, inclusive.
413 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
414 */
415 if (type < 2)
416 return(-1);
417
418 /*
419 * The option data length must have a value between 0 and 255,
420 * inclusive, and is the length of the option data that follows.
421 */
422 if (len > 255 || len < 0 )
423 return(-1);
424
425 /*
426 * The align parameter must have a value of 1, 2, 4, or 8.
427 * The align value can not exceed the value of len.
428 */
429 if (align != 1 && align != 2 && align != 4 && align != 8)
430 return(-1);
431 if (align > len)
432 return(-1);
433
434 /* Calculate the padding length. */
435 currentlen += 2 + len; /* 2 means "type + len" */
436 if (currentlen % align)
437 padlen = align - (currentlen % align);
438
439 /* The option must fit in the extension header buffer. */
440 currentlen += padlen;
441 if (extlen && /* XXX: right? */
442 currentlen > extlen)
443 return(-1);
444
445 if (extbuf) {
446 u_int8_t *optp = (u_int8_t *)extbuf + offset;
447
448 if (padlen == 1) {
449 /* insert a Pad1 option */
450 *optp = IP6OPT_PAD1;
451 optp++;
452 }
453 else if (padlen > 0) {
454 /* insert a PadN option for alignment */
455 *optp++ = IP6OPT_PADN;
456 *optp++ = padlen - 2;
457 memset(optp, 0, padlen - 2);
458 optp += (padlen - 2);
459 }
460
461 *optp++ = type;
462 *optp++ = len;
463
464 *databufp = optp;
465 }
466
467 return(currentlen);
468 }
469
470 int
inet6_opt_finish(void * extbuf,socklen_t extlen,int offset)471 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
472 {
473 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
474
475 if (extbuf) {
476 u_int8_t *padp;
477 int padlen = updatelen - offset;
478
479 if (updatelen > extlen)
480 return(-1);
481
482 padp = (u_int8_t *)extbuf + offset;
483 if (padlen == 1)
484 *padp = IP6OPT_PAD1;
485 else if (padlen > 0) {
486 *padp++ = IP6OPT_PADN;
487 *padp++ = (padlen - 2);
488 memset(padp, 0, padlen - 2);
489 }
490 }
491
492 return(updatelen);
493 }
494
495 int
inet6_opt_set_val(void * databuf,int offset,void * val,socklen_t vallen)496 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
497 {
498
499 memcpy((u_int8_t *)databuf + offset, val, vallen);
500 return(offset + vallen);
501 }
502
503 int
inet6_opt_next(void * extbuf,socklen_t extlen,int offset,u_int8_t * typep,socklen_t * lenp,void ** databufp)504 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
505 socklen_t *lenp, void **databufp)
506 {
507 u_int8_t *optp, *lim;
508 int optlen;
509
510 /* Validate extlen. XXX: is the variable really necessary?? */
511 if (extlen == 0 || (extlen % 8))
512 return(-1);
513 lim = (u_int8_t *)extbuf + extlen;
514
515 /*
516 * If this is the first time this function called for this options
517 * header, simply return the 1st option.
518 * Otherwise, search the option list for the next option.
519 */
520 if (offset == 0) {
521 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
522 }
523 else
524 optp = (u_int8_t *)extbuf + offset;
525
526 /* Find the next option skipping any padding options. */
527 while(optp < lim) {
528 switch(*optp) {
529 case IP6OPT_PAD1:
530 optp++;
531 break;
532 case IP6OPT_PADN:
533 if ((optlen = ip6optlen(optp, lim)) == 0)
534 goto optend;
535 optp += optlen;
536 break;
537 default: /* found */
538 if ((optlen = ip6optlen(optp, lim)) == 0)
539 goto optend;
540 *typep = *optp;
541 *lenp = optlen - 2;
542 *databufp = optp + 2;
543 return(optp + optlen - (u_int8_t *)extbuf);
544 }
545 }
546
547 optend:
548 *databufp = NULL; /* for safety */
549 return(-1);
550 }
551
552 int
inet6_opt_find(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t * lenp,void ** databufp)553 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
554 socklen_t *lenp, void **databufp)
555 {
556 u_int8_t *optp, *lim;
557 int optlen;
558
559 /* Validate extlen. XXX: is the variable really necessary?? */
560 if (extlen == 0 || (extlen % 8))
561 return(-1);
562 lim = (u_int8_t *)extbuf + extlen;
563
564 /*
565 * If this is the first time this function called for this options
566 * header, simply return the 1st option.
567 * Otherwise, search the option list for the next option.
568 */
569 if (offset == 0) {
570 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
571 }
572 else
573 optp = (u_int8_t *)extbuf + offset;
574
575 /* Find the specified option */
576 while(optp < lim) {
577 if ((optlen = ip6optlen(optp, lim)) == 0)
578 goto optend;
579
580 if (*optp == type) { /* found */
581 *lenp = optlen - 2;
582 *databufp = optp + 2;
583 return(optp + optlen - (u_int8_t *)extbuf);
584 }
585
586 optp += optlen;
587 }
588
589 optend:
590 *databufp = NULL; /* for safety */
591 return(-1);
592 }
593
594 int
inet6_opt_get_val(void * databuf,int offset,void * val,socklen_t vallen)595 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
596 {
597
598 /* we can't assume alignment here */
599 memcpy(val, (u_int8_t *)databuf + offset, vallen);
600
601 return(offset + vallen);
602 }
603