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/socket.h>
37
38 #include <netinet/in.h>
39 #include <netinet/ip6.h>
40
41 #include <string.h>
42 #include <stdio.h>
43
44 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
45 static void inet6_insert_padopt(u_char *p, int len);
46
47 #ifndef IPV6_2292HOPOPTS
48 #define IPV6_2292HOPOPTS 22
49 #endif
50 #ifndef IPV6_2292DSTOPTS
51 #define IPV6_2292DSTOPTS 23
52 #endif
53
54 #define is_ipv6_hopopts(x) \
55 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
56 #define is_ipv6_dstopts(x) \
57 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
58
59 /*
60 * This function returns the number of bytes required to hold an option
61 * when it is stored as ancillary data, including the cmsghdr structure
62 * at the beginning, and any padding at the end (to make its size a
63 * multiple of 8 bytes). The argument is the size of the structure
64 * defining the option, which must include any pad bytes at the
65 * beginning (the value y in the alignment term "xn + y"), the type
66 * byte, the length byte, and the option data.
67 */
68 int
inet6_option_space(int nbytes)69 inet6_option_space(int nbytes)
70 {
71 nbytes += 2; /* we need space for nxt-hdr and length fields */
72 return(CMSG_SPACE((nbytes + 7) & ~7));
73 }
74
75 /*
76 * This function is called once per ancillary data object that will
77 * contain either Hop-by-Hop or Destination options. It returns 0 on
78 * success or -1 on an error.
79 */
80 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)81 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
82 {
83 struct cmsghdr *ch = (struct cmsghdr *)bp;
84
85 /* argument validation */
86 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
87 return(-1);
88
89 ch->cmsg_level = IPPROTO_IPV6;
90 ch->cmsg_type = type;
91 ch->cmsg_len = CMSG_LEN(0);
92
93 *cmsgp = ch;
94 return(0);
95 }
96
97 /*
98 * This function appends a Hop-by-Hop option or a Destination option
99 * into an ancillary data object that has been initialized by
100 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
101 * an error.
102 * multx is the value x in the alignment term "xn + y" described
103 * earlier. It must have a value of 1, 2, 4, or 8.
104 * plusy is the value y in the alignment term "xn + y" described
105 * earlier. It must have a value between 0 and 7, inclusive.
106 */
107 int
inet6_option_append(struct cmsghdr * cmsg,const u_int8_t * typep,int multx,int plusy)108 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
109 int plusy)
110 {
111 int padlen, optlen, off;
112 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
113 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
114
115 /* argument validation */
116 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
117 return(-1);
118 if (plusy < 0 || plusy > 7)
119 return(-1);
120
121 /*
122 * If this is the first option, allocate space for the
123 * first 2 bytes(for next header and length fields) of
124 * the option header.
125 */
126 if (bp == (u_char *)eh) {
127 bp += 2;
128 cmsg->cmsg_len += 2;
129 }
130
131 /* calculate pad length before the option. */
132 off = bp - (u_char *)eh;
133 padlen = roundup2(off % multx, multx) - (off % multx);
134 padlen += plusy;
135 padlen %= multx; /* keep the pad as short as possible */
136 /* insert padding */
137 inet6_insert_padopt(bp, padlen);
138 cmsg->cmsg_len += padlen;
139 bp += padlen;
140
141 /* copy the option */
142 if (typep[0] == IP6OPT_PAD1)
143 optlen = 1;
144 else
145 optlen = typep[1] + 2;
146 memcpy(bp, typep, optlen);
147 bp += optlen;
148 cmsg->cmsg_len += optlen;
149
150 /* calculate pad length after the option and insert the padding */
151 off = bp - (u_char *)eh;
152 padlen = ((off + 7) & ~7) - off;
153 inet6_insert_padopt(bp, padlen);
154 bp += padlen;
155 cmsg->cmsg_len += padlen;
156
157 /* update the length field of the ip6 option header */
158 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
159
160 return(0);
161 }
162
163 /*
164 * This function appends a Hop-by-Hop option or a Destination option
165 * into an ancillary data object that has been initialized by
166 * inet6_option_init(). This function returns a pointer to the 8-bit
167 * option type field that starts the option on success, or NULL on an
168 * error.
169 * The difference between this function and inet6_option_append() is
170 * that the latter copies the contents of a previously built option into
171 * the ancillary data object while the current function returns a
172 * pointer to the space in the data object where the option's TLV must
173 * then be built by the caller.
174 *
175 */
176 u_int8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)177 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
178 {
179 int padlen, off;
180 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
181 u_int8_t *retval;
182 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
183
184 /* argument validation */
185 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
186 return(NULL);
187 if (plusy < 0 || plusy > 7)
188 return(NULL);
189
190 /*
191 * If this is the first option, allocate space for the
192 * first 2 bytes(for next header and length fields) of
193 * the option header.
194 */
195 if (bp == (u_char *)eh) {
196 bp += 2;
197 cmsg->cmsg_len += 2;
198 }
199
200 /* calculate pad length before the option. */
201 off = bp - (u_char *)eh;
202 padlen = roundup2(off % multx, multx) - (off % multx);
203 padlen += plusy;
204 padlen %= multx; /* keep the pad as short as possible */
205 /* insert padding */
206 inet6_insert_padopt(bp, padlen);
207 cmsg->cmsg_len += padlen;
208 bp += padlen;
209
210 /* keep space to store specified length of data */
211 retval = bp;
212 bp += datalen;
213 cmsg->cmsg_len += datalen;
214
215 /* calculate pad length after the option and insert the padding */
216 off = bp - (u_char *)eh;
217 padlen = ((off + 7) & ~7) - off;
218 inet6_insert_padopt(bp, padlen);
219 bp += padlen;
220 cmsg->cmsg_len += padlen;
221
222 /* update the length field of the ip6 option header */
223 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
224
225 return(retval);
226 }
227
228 /*
229 * This function processes the next Hop-by-Hop option or Destination
230 * option in an ancillary data object. If another option remains to be
231 * processed, the return value of the function is 0 and *tptrp points to
232 * the 8-bit option type field (which is followed by the 8-bit option
233 * data length, followed by the option data). If no more options remain
234 * to be processed, the return value is -1 and *tptrp is NULL. If an
235 * error occurs, the return value is -1 and *tptrp is not NULL.
236 * (RFC 2292, 6.3.5)
237 */
238 int
inet6_option_next(const struct cmsghdr * cmsg,u_int8_t ** tptrp)239 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
240 {
241 struct ip6_ext *ip6e;
242 int hdrlen, optlen;
243 u_int8_t *lim;
244
245 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
246 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
247 !is_ipv6_dstopts(cmsg->cmsg_type)))
248 return(-1);
249
250 /* message length validation */
251 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
252 return(-1);
253 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
254 hdrlen = (ip6e->ip6e_len + 1) << 3;
255 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
256 return(-1);
257
258 /*
259 * If the caller does not specify the starting point,
260 * simply return the 1st option.
261 * Otherwise, search the option list for the next option.
262 */
263 lim = (u_int8_t *)ip6e + hdrlen;
264 if (*tptrp == NULL)
265 *tptrp = (u_int8_t *)(ip6e + 1);
266 else {
267 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
268 return(-1);
269
270 *tptrp = *tptrp + optlen;
271 }
272 if (*tptrp >= lim) { /* there is no option */
273 *tptrp = NULL;
274 return(-1);
275 }
276 /*
277 * Finally, checks if the next option is safely stored in the
278 * cmsg data.
279 */
280 if (ip6optlen(*tptrp, lim) == 0)
281 return(-1);
282 else
283 return(0);
284 }
285
286 /*
287 * This function is similar to the inet6_option_next() function,
288 * except this function lets the caller specify the option type to be
289 * searched for, instead of always returning the next option in the
290 * ancillary data object.
291 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
292 * it's a typo. The variable should be type of u_int8_t **.
293 */
294 int
inet6_option_find(const struct cmsghdr * cmsg,u_int8_t ** tptrp,int type)295 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
296 {
297 struct ip6_ext *ip6e;
298 int hdrlen, optlen;
299 u_int8_t *optp, *lim;
300
301 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
302 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
303 !is_ipv6_dstopts(cmsg->cmsg_type)))
304 return(-1);
305
306 /* message length validation */
307 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
308 return(-1);
309 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
310 hdrlen = (ip6e->ip6e_len + 1) << 3;
311 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
312 return(-1);
313
314 /*
315 * If the caller does not specify the starting point,
316 * search from the beginning of the option list.
317 * Otherwise, search from *the next option* of the specified point.
318 */
319 lim = (u_int8_t *)ip6e + hdrlen;
320 if (*tptrp == NULL)
321 *tptrp = (u_int8_t *)(ip6e + 1);
322 else {
323 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
324 return(-1);
325
326 *tptrp = *tptrp + optlen;
327 }
328 for (optp = *tptrp; optp < lim; optp += optlen) {
329 if (*optp == type) {
330 *tptrp = optp;
331 return(0);
332 }
333 if ((optlen = ip6optlen(optp, lim)) == 0)
334 return(-1);
335 }
336
337 /* search failed */
338 *tptrp = NULL;
339 return(-1);
340 }
341
342 /*
343 * Calculate the length of a given IPv6 option. Also checks
344 * if the option is safely stored in user's buffer according to the
345 * calculated length and the limitation of the buffer.
346 */
347 static int
ip6optlen(u_int8_t * opt,u_int8_t * lim)348 ip6optlen(u_int8_t *opt, u_int8_t *lim)
349 {
350 int optlen;
351
352 if (*opt == IP6OPT_PAD1)
353 optlen = 1;
354 else {
355 /* is there enough space to store type and len? */
356 if (opt + 2 > lim)
357 return(0);
358 optlen = *(opt + 1) + 2;
359 }
360 if (opt + optlen <= lim)
361 return(optlen);
362
363 return(0);
364 }
365
366 static void
inet6_insert_padopt(u_char * p,int len)367 inet6_insert_padopt(u_char *p, int len)
368 {
369 switch(len) {
370 case 0:
371 return;
372 case 1:
373 p[0] = IP6OPT_PAD1;
374 return;
375 default:
376 p[0] = IP6OPT_PADN;
377 p[1] = len - 2;
378 memset(&p[2], 0, len - 2);
379 return;
380 }
381 }
382
383 /*
384 * The following functions are defined in RFC3542, which is a successor
385 * of RFC2292.
386 */
387
388 int
inet6_opt_init(void * extbuf,socklen_t extlen)389 inet6_opt_init(void *extbuf, socklen_t extlen)
390 {
391 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
392
393 if (ext) {
394 if (extlen <= 0 || (extlen % 8))
395 return(-1);
396 ext->ip6e_len = (extlen >> 3) - 1;
397 }
398
399 return(2); /* sizeof the next and the length fields */
400 }
401
402 int
inet6_opt_append(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t len,u_int8_t align,void ** databufp)403 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
404 socklen_t len, u_int8_t align, void **databufp)
405 {
406 int currentlen = offset, padlen = 0;
407
408 /*
409 * The option type must have a value from 2 to 255, inclusive.
410 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
411 */
412 if (type < 2)
413 return(-1);
414
415 /*
416 * The option data length must have a value between 0 and 255,
417 * inclusive, and is the length of the option data that follows.
418 */
419 if (len > 255 || len < 0 )
420 return(-1);
421
422 /*
423 * The align parameter must have a value of 1, 2, 4, or 8.
424 * The align value can not exceed the value of len.
425 */
426 if (align != 1 && align != 2 && align != 4 && align != 8)
427 return(-1);
428 if (align > len)
429 return(-1);
430
431 /* Calculate the padding length. */
432 currentlen += 2 + len; /* 2 means "type + len" */
433 if (currentlen % align)
434 padlen = align - (currentlen % align);
435
436 /* The option must fit in the extension header buffer. */
437 currentlen += padlen;
438 if (extlen && /* XXX: right? */
439 currentlen > extlen)
440 return(-1);
441
442 if (extbuf) {
443 u_int8_t *optp = (u_int8_t *)extbuf + offset;
444
445 if (padlen == 1) {
446 /* insert a Pad1 option */
447 *optp = IP6OPT_PAD1;
448 optp++;
449 }
450 else if (padlen > 0) {
451 /* insert a PadN option for alignment */
452 *optp++ = IP6OPT_PADN;
453 *optp++ = padlen - 2;
454 memset(optp, 0, padlen - 2);
455 optp += (padlen - 2);
456 }
457
458 *optp++ = type;
459 *optp++ = len;
460
461 *databufp = optp;
462 }
463
464 return(currentlen);
465 }
466
467 int
inet6_opt_finish(void * extbuf,socklen_t extlen,int offset)468 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
469 {
470 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
471
472 if (extbuf) {
473 u_int8_t *padp;
474 int padlen = updatelen - offset;
475
476 if (updatelen > extlen)
477 return(-1);
478
479 padp = (u_int8_t *)extbuf + offset;
480 if (padlen == 1)
481 *padp = IP6OPT_PAD1;
482 else if (padlen > 0) {
483 *padp++ = IP6OPT_PADN;
484 *padp++ = (padlen - 2);
485 memset(padp, 0, padlen - 2);
486 }
487 }
488
489 return(updatelen);
490 }
491
492 int
inet6_opt_set_val(void * databuf,int offset,void * val,socklen_t vallen)493 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
494 {
495
496 memcpy((u_int8_t *)databuf + offset, val, vallen);
497 return(offset + vallen);
498 }
499
500 int
inet6_opt_next(void * extbuf,socklen_t extlen,int offset,u_int8_t * typep,socklen_t * lenp,void ** databufp)501 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
502 socklen_t *lenp, void **databufp)
503 {
504 u_int8_t *optp, *lim;
505 int optlen;
506
507 /* Validate extlen. XXX: is the variable really necessary?? */
508 if (extlen == 0 || (extlen % 8))
509 return(-1);
510 lim = (u_int8_t *)extbuf + extlen;
511
512 /*
513 * If this is the first time this function called for this options
514 * header, simply return the 1st option.
515 * Otherwise, search the option list for the next option.
516 */
517 if (offset == 0) {
518 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
519 }
520 else
521 optp = (u_int8_t *)extbuf + offset;
522
523 /* Find the next option skipping any padding options. */
524 while(optp < lim) {
525 switch(*optp) {
526 case IP6OPT_PAD1:
527 optp++;
528 break;
529 case IP6OPT_PADN:
530 if ((optlen = ip6optlen(optp, lim)) == 0)
531 goto optend;
532 optp += optlen;
533 break;
534 default: /* found */
535 if ((optlen = ip6optlen(optp, lim)) == 0)
536 goto optend;
537 *typep = *optp;
538 *lenp = optlen - 2;
539 *databufp = optp + 2;
540 return(optp + optlen - (u_int8_t *)extbuf);
541 }
542 }
543
544 optend:
545 *databufp = NULL; /* for safety */
546 return(-1);
547 }
548
549 int
inet6_opt_find(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t * lenp,void ** databufp)550 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
551 socklen_t *lenp, void **databufp)
552 {
553 u_int8_t *optp, *lim;
554 int optlen;
555
556 /* Validate extlen. XXX: is the variable really necessary?? */
557 if (extlen == 0 || (extlen % 8))
558 return(-1);
559 lim = (u_int8_t *)extbuf + extlen;
560
561 /*
562 * If this is the first time this function called for this options
563 * header, simply return the 1st option.
564 * Otherwise, search the option list for the next option.
565 */
566 if (offset == 0) {
567 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
568 }
569 else
570 optp = (u_int8_t *)extbuf + offset;
571
572 /* Find the specified option */
573 while(optp < lim) {
574 if ((optlen = ip6optlen(optp, lim)) == 0)
575 goto optend;
576
577 if (*optp == type) { /* found */
578 *lenp = optlen - 2;
579 *databufp = optp + 2;
580 return(optp + optlen - (u_int8_t *)extbuf);
581 }
582
583 optp += optlen;
584 }
585
586 optend:
587 *databufp = NULL; /* for safety */
588 return(-1);
589 }
590
591 int
inet6_opt_get_val(void * databuf,int offset,void * val,socklen_t vallen)592 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
593 {
594
595 /* we can't assume alignment here */
596 memcpy(val, (u_int8_t *)databuf + offset, vallen);
597
598 return(offset + vallen);
599 }
600