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 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.8 2005/07/19 18:13:58 ume Exp $
32 */
33
34 #include <sys/param.h>
35 #include <sys/types.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 /*
48 * This function returns the number of bytes required to hold an option
49 * when it is stored as ancillary data, including the cmsghdr structure
50 * at the beginning, and any padding at the end (to make its size a
51 * multiple of 8 bytes). The argument is the size of the structure
52 * defining the option, which must include any pad bytes at the
53 * beginning (the value y in the alignment term "xn + y"), the type
54 * byte, the length byte, and the option data.
55 */
56 int
inet6_option_space(int nbytes)57 inet6_option_space(int nbytes)
58 {
59 nbytes += 2; /* we need space for nxt-hdr and length fields */
60 return(CMSG_SPACE((nbytes + 7) & ~7));
61 }
62
63 /*
64 * This function is called once per ancillary data object that will
65 * contain either Hop-by-Hop or Destination options. It returns 0 on
66 * success or -1 on an error.
67 */
68 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)69 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
70 {
71 struct cmsghdr *ch = (struct cmsghdr *)bp;
72
73 /* argument validation */
74 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
75 return(-1);
76
77 ch->cmsg_level = IPPROTO_IPV6;
78 ch->cmsg_type = type;
79 ch->cmsg_len = CMSG_LEN(0);
80
81 *cmsgp = ch;
82 return(0);
83 }
84
85 /*
86 * This function appends a Hop-by-Hop option or a Destination option
87 * into an ancillary data object that has been initialized by
88 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
89 * an error.
90 * multx is the value x in the alignment term "xn + y" described
91 * earlier. It must have a value of 1, 2, 4, or 8.
92 * plusy is the value y in the alignment term "xn + y" described
93 * earlier. It must have a value between 0 and 7, inclusive.
94 */
95 int
inet6_option_append(struct cmsghdr * cmsg,const u_int8_t * typep,int multx,int plusy)96 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
97 int plusy)
98 {
99 int padlen, optlen, off;
100 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
101 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
102
103 /* argument validation */
104 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
105 return(-1);
106 if (plusy < 0 || plusy > 7)
107 return(-1);
108
109 /*
110 * If this is the first option, allocate space for the
111 * first 2 bytes(for next header and length fields) of
112 * the option header.
113 */
114 if (bp == (u_char *)eh) {
115 bp += 2;
116 cmsg->cmsg_len += 2;
117 }
118
119 /* calculate pad length before the option. */
120 off = bp - (u_char *)eh;
121 padlen = roundup2(off % multx, multx) - (off % multx);
122 padlen += plusy;
123 padlen %= multx; /* keep the pad as short as possible */
124 /* insert padding */
125 inet6_insert_padopt(bp, padlen);
126 cmsg->cmsg_len += padlen;
127 bp += padlen;
128
129 /* copy the option */
130 if (typep[0] == IP6OPT_PAD1)
131 optlen = 1;
132 else
133 optlen = typep[1] + 2;
134 memcpy(bp, typep, optlen);
135 bp += optlen;
136 cmsg->cmsg_len += optlen;
137
138 /* calculate pad length after the option and insert the padding */
139 off = bp - (u_char *)eh;
140 padlen = ((off + 7) & ~7) - off;
141 inet6_insert_padopt(bp, padlen);
142 bp += padlen;
143 cmsg->cmsg_len += padlen;
144
145 /* update the length field of the ip6 option header */
146 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
147
148 return(0);
149 }
150
151 /*
152 * This function appends a Hop-by-Hop option or a Destination option
153 * into an ancillary data object that has been initialized by
154 * inet6_option_init(). This function returns a pointer to the 8-bit
155 * option type field that starts the option on success, or NULL on an
156 * error.
157 * The difference between this function and inet6_option_append() is
158 * that the latter copies the contents of a previously built option into
159 * the ancillary data object while the current function returns a
160 * pointer to the space in the data object where the option's TLV must
161 * then be built by the caller.
162 *
163 */
164 u_int8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)165 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
166 {
167 int padlen, off;
168 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
169 u_int8_t *retval;
170 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
171
172 /* argument validation */
173 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
174 return(NULL);
175 if (plusy < 0 || plusy > 7)
176 return(NULL);
177
178 /*
179 * If this is the first option, allocate space for the
180 * first 2 bytes(for next header and length fields) of
181 * the option header.
182 */
183 if (bp == (u_char *)eh) {
184 bp += 2;
185 cmsg->cmsg_len += 2;
186 }
187
188 /* calculate pad length before the option. */
189 off = bp - (u_char *)eh;
190 padlen = roundup2(off % multx, multx) - (off % multx);
191 padlen += plusy;
192 padlen %= multx; /* keep the pad as short as possible */
193 /* insert padding */
194 inet6_insert_padopt(bp, padlen);
195 cmsg->cmsg_len += padlen;
196 bp += padlen;
197
198 /* keep space to store specified length of data */
199 retval = bp;
200 bp += datalen;
201 cmsg->cmsg_len += datalen;
202
203 /* calculate pad length after the option and insert the padding */
204 off = bp - (u_char *)eh;
205 padlen = ((off + 7) & ~7) - off;
206 inet6_insert_padopt(bp, padlen);
207 bp += padlen;
208 cmsg->cmsg_len += padlen;
209
210 /* update the length field of the ip6 option header */
211 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
212
213 return(retval);
214 }
215
216 /*
217 * This function processes the next Hop-by-Hop option or Destination
218 * option in an ancillary data object. If another option remains to be
219 * processed, the return value of the function is 0 and *tptrp points to
220 * the 8-bit option type field (which is followed by the 8-bit option
221 * data length, followed by the option data). If no more options remain
222 * to be processed, the return value is -1 and *tptrp is NULL. If an
223 * error occurs, the return value is -1 and *tptrp is not NULL.
224 * (RFC 2292, 6.3.5)
225 */
226 int
inet6_option_next(const struct cmsghdr * cmsg,u_int8_t ** tptrp)227 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
228 {
229 struct ip6_ext *ip6e;
230 int hdrlen, optlen;
231 u_int8_t *lim;
232
233 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
234 (cmsg->cmsg_type != IPV6_HOPOPTS &&
235 cmsg->cmsg_type != IPV6_DSTOPTS))
236 return(-1);
237
238 /* message length validation */
239 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
240 return(-1);
241 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
242 hdrlen = (ip6e->ip6e_len + 1) << 3;
243 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
244 return(-1);
245
246 /*
247 * If the caller does not specify the starting point,
248 * simply return the 1st option.
249 * Otherwise, search the option list for the next option.
250 */
251 lim = (u_int8_t *)ip6e + hdrlen;
252 if (*tptrp == NULL)
253 *tptrp = (u_int8_t *)(ip6e + 1);
254 else {
255 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
256 return(-1);
257
258 *tptrp = *tptrp + optlen;
259 }
260 if (*tptrp >= lim) { /* there is no option */
261 *tptrp = NULL;
262 return(-1);
263 }
264 /*
265 * Finally, checks if the next option is safely stored in the
266 * cmsg data.
267 */
268 if (ip6optlen(*tptrp, lim) == 0)
269 return(-1);
270 else
271 return(0);
272 }
273
274 /*
275 * This function is similar to the inet6_option_next() function,
276 * except this function lets the caller specify the option type to be
277 * searched for, instead of always returning the next option in the
278 * ancillary data object.
279 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
280 * it's a typo. The variable should be type of u_int8_t **.
281 */
282 int
inet6_option_find(const struct cmsghdr * cmsg,u_int8_t ** tptrp,int type)283 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
284 {
285 struct ip6_ext *ip6e;
286 int hdrlen, optlen;
287 u_int8_t *optp, *lim;
288
289 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
290 (cmsg->cmsg_type != IPV6_HOPOPTS &&
291 cmsg->cmsg_type != IPV6_DSTOPTS))
292 return(-1);
293
294 /* message length validation */
295 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
296 return(-1);
297 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
298 hdrlen = (ip6e->ip6e_len + 1) << 3;
299 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
300 return(-1);
301
302 /*
303 * If the caller does not specify the starting point,
304 * search from the beginning of the option list.
305 * Otherwise, search from *the next option* of the specified point.
306 */
307 lim = (u_int8_t *)ip6e + hdrlen;
308 if (*tptrp == NULL)
309 *tptrp = (u_int8_t *)(ip6e + 1);
310 else {
311 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
312 return(-1);
313
314 *tptrp = *tptrp + optlen;
315 }
316 for (optp = *tptrp; optp < lim; optp += optlen) {
317 if (*optp == type) {
318 *tptrp = optp;
319 return(0);
320 }
321 if ((optlen = ip6optlen(optp, lim)) == 0)
322 return(-1);
323 }
324
325 /* search failed */
326 *tptrp = NULL;
327 return(-1);
328 }
329
330 /*
331 * Calculate the length of a given IPv6 option. Also checks
332 * if the option is safely stored in user's buffer according to the
333 * calculated length and the limitation of the buffer.
334 */
335 static int
ip6optlen(u_int8_t * opt,u_int8_t * lim)336 ip6optlen(u_int8_t *opt, u_int8_t *lim)
337 {
338 int optlen;
339
340 if (*opt == IP6OPT_PAD1)
341 optlen = 1;
342 else {
343 /* is there enough space to store type and len? */
344 if (opt + 2 > lim)
345 return(0);
346 optlen = *(opt + 1) + 2;
347 }
348 if (opt + optlen <= lim)
349 return(optlen);
350
351 return(0);
352 }
353
354 static void
inet6_insert_padopt(u_char * p,int len)355 inet6_insert_padopt(u_char *p, int len)
356 {
357 switch(len) {
358 case 0:
359 return;
360 case 1:
361 p[0] = IP6OPT_PAD1;
362 return;
363 default:
364 p[0] = IP6OPT_PADN;
365 p[1] = len - 2;
366 memset(&p[2], 0, len - 2);
367 return;
368 }
369 }
370
371 /*
372 * The following functions are defined in RFC3542, which is a successor
373 * of RFC2292.
374 */
375
376 int
inet6_opt_init(void * extbuf,socklen_t extlen)377 inet6_opt_init(void *extbuf, socklen_t extlen)
378 {
379 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
380
381 if (ext) {
382 if (extlen <= 0 || (extlen % 8))
383 return(-1);
384 ext->ip6e_len = (extlen >> 3) - 1;
385 }
386
387 return(2); /* sizeof the next and the length fields */
388 }
389
390 int
inet6_opt_append(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t len,u_int8_t align,void ** databufp)391 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
392 socklen_t len, u_int8_t align, void **databufp)
393 {
394 int currentlen = offset, padlen = 0;
395
396 /*
397 * The option type must have a value from 2 to 255, inclusive.
398 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
399 */
400 if (type < 2)
401 return(-1);
402
403 /*
404 * The option data length must have a value between 0 and 255,
405 * inclusive, and is the length of the option data that follows.
406 */
407 if (len > 255)
408 return(-1);
409
410 /*
411 * The align parameter must have a value of 1, 2, 4, or 8.
412 * The align value can not exceed the value of len.
413 */
414 if (align != 1 && align != 2 && align != 4 && align != 8)
415 return(-1);
416 if (align > len)
417 return(-1);
418
419 /* Calculate the padding length. */
420 currentlen += 2 + len; /* 2 means "type + len" */
421 if (currentlen % align)
422 padlen = align - (currentlen % align);
423
424 /* The option must fit in the extension header buffer. */
425 currentlen += padlen;
426 if (extlen && /* XXX: right? */
427 currentlen > extlen)
428 return(-1);
429
430 if (extbuf) {
431 u_int8_t *optp = (u_int8_t *)extbuf + offset;
432
433 if (padlen == 1) {
434 /* insert a Pad1 option */
435 *optp = IP6OPT_PAD1;
436 optp++;
437 } else if (padlen > 0) {
438 /* insert a PadN option for alignment */
439 *optp++ = IP6OPT_PADN;
440 *optp++ = padlen - 2;
441 memset(optp, 0, padlen - 2);
442 optp += (padlen - 2);
443 }
444
445 *optp++ = type;
446 *optp++ = len;
447
448 *databufp = optp;
449 }
450
451 return(currentlen);
452 }
453
454 int
inet6_opt_finish(void * extbuf,socklen_t extlen,int offset)455 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
456 {
457 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
458
459 if (extbuf) {
460 u_int8_t *padp;
461 int padlen = updatelen - offset;
462
463 if (updatelen > extlen)
464 return(-1);
465
466 padp = (u_int8_t *)extbuf + offset;
467 if (padlen == 1)
468 *padp = IP6OPT_PAD1;
469 else if (padlen > 0) {
470 *padp++ = IP6OPT_PADN;
471 *padp++ = (padlen - 2);
472 memset(padp, 0, padlen - 2);
473 }
474 }
475
476 return(updatelen);
477 }
478
479 int
inet6_opt_set_val(void * databuf,int offset,void * val,socklen_t vallen)480 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
481 {
482
483 memcpy((u_int8_t *)databuf + offset, val, vallen);
484 return(offset + vallen);
485 }
486
487 int
inet6_opt_next(void * extbuf,socklen_t extlen,int offset,u_int8_t * typep,socklen_t * lenp,void ** databufp)488 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
489 socklen_t *lenp, void **databufp)
490 {
491 u_int8_t *optp, *lim;
492 int optlen;
493
494 /* Validate extlen. XXX: is the variable really necessary?? */
495 if (extlen == 0 || (extlen % 8))
496 return(-1);
497 lim = (u_int8_t *)extbuf + extlen;
498
499 /*
500 * If this is the first time this function called for this options
501 * header, simply return the 1st option.
502 * Otherwise, search the option list for the next option.
503 */
504 if (offset == 0)
505 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
506 else
507 optp = (u_int8_t *)extbuf + offset;
508
509 /* Find the next option skipping any padding options. */
510 while (optp < lim) {
511 switch (*optp) {
512 case IP6OPT_PAD1:
513 optp++;
514 break;
515 case IP6OPT_PADN:
516 if ((optlen = ip6optlen(optp, lim)) == 0)
517 goto optend;
518 optp += optlen;
519 break;
520 default: /* found */
521 if ((optlen = ip6optlen(optp, lim)) == 0)
522 goto optend;
523 *typep = *optp;
524 *lenp = optlen - 2;
525 *databufp = optp + 2;
526 return(optp + optlen - (u_int8_t *)extbuf);
527 }
528 }
529
530 optend:
531 *databufp = NULL; /* for safety */
532 return(-1);
533 }
534
535 int
inet6_opt_find(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t * lenp,void ** databufp)536 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
537 socklen_t *lenp, void **databufp)
538 {
539 u_int8_t *optp, *lim;
540 int optlen;
541
542 /* Validate extlen. XXX: is the variable really necessary?? */
543 if (extlen == 0 || (extlen % 8))
544 return(-1);
545 lim = (u_int8_t *)extbuf + extlen;
546
547 /*
548 * If this is the first time this function called for this options
549 * header, simply return the 1st option.
550 * Otherwise, search the option list for the next option.
551 */
552 if (offset == 0)
553 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
554 else
555 optp = (u_int8_t *)extbuf + offset;
556
557 /* Find the specified option */
558 while (optp < lim) {
559 if ((optlen = ip6optlen(optp, lim)) == 0)
560 goto optend;
561
562 if (*optp == type) { /* found */
563 *lenp = optlen - 2;
564 *databufp = optp + 2;
565 return(optp + optlen - (u_int8_t *)extbuf);
566 }
567
568 optp += optlen;
569 }
570
571 optend:
572 *databufp = NULL; /* for safety */
573 return(-1);
574 }
575
576 int
inet6_opt_get_val(void * databuf,int offset,void * val,socklen_t vallen)577 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
578 {
579
580 /* we can't assume alignment here */
581 memcpy(val, (u_int8_t *)databuf + offset, vallen);
582
583 return(offset + vallen);
584 }
585