1 /* $NetBSD: ip6opt.c,v 1.15 2014/02/07 02:36:06 christos 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 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: ip6opt.c,v 1.15 2014/02/07 02:36:06 christos Exp $");
35 #endif /* LIBC_SCCS and not lint */
36
37 #include "namespace.h"
38 #include <sys/param.h>
39 #include <sys/types.h>
40 #include <sys/socket.h>
41
42 #include <netinet/in.h>
43 #include <netinet/ip6.h>
44
45 #include <assert.h>
46 #include <stddef.h>
47 #include <string.h>
48 #include <stdio.h>
49
50 #ifdef __weak_alias
51 __weak_alias(inet6_option_alloc,_inet6_option_alloc)
52 __weak_alias(inet6_option_append,_inet6_option_append)
53 __weak_alias(inet6_option_find,_inet6_option_find)
54 __weak_alias(inet6_option_init,_inet6_option_init)
55 __weak_alias(inet6_option_next,_inet6_option_next)
56 __weak_alias(inet6_option_space,_inet6_option_space)
57 __weak_alias(inet6_opt_init, _inet6_opt_init)
58 __weak_alias(inet6_opt_append, _inet6_opt_append)
59 __weak_alias(inet6_opt_finish, _inet6_opt_finish)
60 __weak_alias(inet6_opt_set_val, _inet6_opt_set_val)
61 __weak_alias(inet6_opt_next, _inet6_opt_next)
62 __weak_alias(inet6_opt_find, _inet6_opt_find)
63 __weak_alias(inet6_opt_get_val, _inet6_opt_get_val)
64 #endif
65
66 static int ip6optlen(uint8_t *opt, uint8_t *lim);
67 static void inet6_insert_padopt(uint8_t *p, size_t len);
68
69 /*
70 * This function returns the number of bytes required to hold an option
71 * when it is stored as ancillary data, including the cmsghdr structure
72 * at the beginning, and any padding at the end (to make its size a
73 * multiple of 8 bytes). The argument is the size of the structure
74 * defining the option, which must include any pad bytes at the
75 * beginning (the value y in the alignment term "xn + y"), the type
76 * byte, the length byte, and the option data.
77 */
78 int
inet6_option_space(int nbytes)79 inet6_option_space(int nbytes)
80 {
81 size_t sp;
82 nbytes += 2; /* we need space for nxt-hdr and length fields */
83 sp = CMSG_SPACE((nbytes + 7) & ~7);
84 _DIAGASSERT(__type_fit(int, sp));
85 return (int)sp;
86 }
87
88 /*
89 * This function is called once per ancillary data object that will
90 * contain either Hop-by-Hop or Destination options. It returns 0 on
91 * success or -1 on an error.
92 */
93 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)94 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
95 {
96 register struct cmsghdr *ch;
97
98 _DIAGASSERT(bp != NULL);
99 _DIAGASSERT(cmsgp != NULL);
100
101 ch = (struct cmsghdr *)bp;
102
103 /* argument validation */
104 if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)
105 return(-1);
106
107 ch->cmsg_level = IPPROTO_IPV6;
108 ch->cmsg_type = type;
109 ch->cmsg_len = CMSG_LEN(0);
110
111 *cmsgp = ch;
112 return(0);
113 }
114
115 /*
116 * This function appends a Hop-by-Hop option or a Destination option
117 * into an ancillary data object that has been initialized by
118 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
119 * an error.
120 * multx is the value x in the alignment term "xn + y" described
121 * earlier. It must have a value of 1, 2, 4, or 8.
122 * plusy is the value y in the alignment term "xn + y" described
123 * earlier. It must have a value between 0 and 7, inclusive.
124 */
125 int
inet6_option_append(struct cmsghdr * cmsg,const uint8_t * typep,int multx,int plusy)126 inet6_option_append(struct cmsghdr *cmsg, const uint8_t *typep, int multx,
127 int plusy)
128 {
129 size_t padlen, optlen, off;
130 register uint8_t *bp;
131 struct ip6_ext *eh;
132
133 _DIAGASSERT(cmsg != NULL);
134 _DIAGASSERT(typep != NULL);
135
136 bp = (uint8_t *)(void *)cmsg + cmsg->cmsg_len;
137 eh = (struct ip6_ext *)(void *)CMSG_DATA(cmsg);
138
139 /* argument validation */
140 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
141 return(-1);
142 if (plusy < 0 || plusy > 7)
143 return(-1);
144
145 /*
146 * If this is the first option, allocate space for the
147 * first 2 bytes(for next header and length fields) of
148 * the option header.
149 */
150 if (bp == (uint8_t *)(void *)eh) {
151 bp += 2;
152 cmsg->cmsg_len += 2;
153 }
154
155 /* calculate pad length before the option. */
156 off = bp - (uint8_t *)(void *)eh;
157 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
158 (off % multx);
159 padlen += plusy;
160 padlen %= multx; /* keep the pad as short as possible */
161 /* insert padding */
162 inet6_insert_padopt(bp, padlen);
163 _DIAGASSERT(__type_fit(socklen_t, padlen + cmsg->cmsg_len));
164 cmsg->cmsg_len += (socklen_t)padlen;
165 bp += padlen;
166
167 /* copy the option */
168 if (typep[0] == IP6OPT_PAD1)
169 optlen = 1;
170 else
171 optlen = typep[1] + 2;
172 memcpy(bp, typep, (size_t)optlen);
173 bp += optlen;
174 _DIAGASSERT(__type_fit(socklen_t, optlen + cmsg->cmsg_len));
175 cmsg->cmsg_len += (socklen_t)optlen;
176
177 /* calculate pad length after the option and insert the padding */
178 off = bp - (uint8_t *)(void *)eh;
179 padlen = ((off + 7) & ~7) - off;
180 inet6_insert_padopt(bp, padlen);
181 bp += padlen;
182 _DIAGASSERT(__type_fit(socklen_t, padlen + cmsg->cmsg_len));
183 cmsg->cmsg_len += (socklen_t)padlen;
184
185 /* update the length field of the ip6 option header */
186 off = bp - (uint8_t *)(void *)eh;
187 _DIAGASSERT(__type_fit(uint8_t, (off >> 3) - 1));
188 eh->ip6e_len = (uint8_t)((off >> 3) - 1);
189
190 return(0);
191 }
192
193 /*
194 * This function appends a Hop-by-Hop option or a Destination option
195 * into an ancillary data object that has been initialized by
196 * inet6_option_init(). This function returns a pointer to the 8-bit
197 * option type field that starts the option on success, or NULL on an
198 * error.
199 * The difference between this function and inet6_option_append() is
200 * that the latter copies the contents of a previously built option into
201 * the ancillary data object while the current function returns a
202 * pointer to the space in the data object where the option's TLV must
203 * then be built by the caller.
204 *
205 */
206 uint8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)207 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
208 {
209 size_t padlen, off;
210 register uint8_t *bp;
211 uint8_t *retval;
212 struct ip6_ext *eh;
213
214 _DIAGASSERT(cmsg != NULL);
215
216 bp = (uint8_t *)(void *)cmsg + cmsg->cmsg_len;
217 eh = (struct ip6_ext *)(void *)CMSG_DATA(cmsg);
218
219 /* argument validation */
220 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
221 return(NULL);
222 if (plusy < 0 || plusy > 7)
223 return(NULL);
224
225 /*
226 * If this is the first option, allocate space for the
227 * first 2 bytes(for next header and length fields) of
228 * the option header.
229 */
230 if (bp == (uint8_t *)(void *)eh) {
231 bp += 2;
232 cmsg->cmsg_len += 2;
233 }
234
235 /* calculate pad length before the option. */
236 off = bp - (uint8_t *)(void *)eh;
237 padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -
238 (off % multx);
239 padlen += plusy;
240 padlen %= multx; /* keep the pad as short as possible */
241 /* insert padding */
242 inet6_insert_padopt(bp, padlen);
243 cmsg->cmsg_len += (socklen_t)padlen;
244 bp += padlen;
245
246 /* keep space to store specified length of data */
247 retval = bp;
248 bp += datalen;
249 cmsg->cmsg_len += datalen;
250
251 /* calculate pad length after the option and insert the padding */
252 off = bp - (uint8_t *)(void *)eh;
253 padlen = ((off + 7) & ~7) - off;
254 inet6_insert_padopt(bp, padlen);
255 bp += padlen;
256 _DIAGASSERT(__type_fit(socklen_t, padlen + cmsg->cmsg_len));
257 cmsg->cmsg_len += (socklen_t)padlen;
258
259 /* update the length field of the ip6 option header */
260 off = bp - (uint8_t *)(void *)eh;
261 _DIAGASSERT(__type_fit(uint8_t, (off >> 3) - 1));
262 eh->ip6e_len = (uint8_t)((off >> 3) - 1);
263
264 return(retval);
265 }
266
267 /*
268 * This function processes the next Hop-by-Hop option or Destination
269 * option in an ancillary data object. If another option remains to be
270 * processed, the return value of the function is 0 and *tptrp points to
271 * the 8-bit option type field (which is followed by the 8-bit option
272 * data length, followed by the option data). If no more options remain
273 * to be processed, the return value is -1 and *tptrp is NULL. If an
274 * error occurs, the return value is -1 and *tptrp is not NULL.
275 * (RFC 2292, 6.3.5)
276 */
277 int
inet6_option_next(const struct cmsghdr * cmsg,uint8_t ** tptrp)278 inet6_option_next(const struct cmsghdr *cmsg, uint8_t **tptrp)
279 {
280 struct ip6_ext *ip6e;
281 int hdrlen, optlen;
282 uint8_t *lim;
283
284 _DIAGASSERT(cmsg != NULL);
285 _DIAGASSERT(tptrp != NULL);
286
287 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
288 (cmsg->cmsg_type != IPV6_HOPOPTS &&
289 cmsg->cmsg_type != IPV6_DSTOPTS))
290 return(-1);
291
292 /* message length validation */
293 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
294 return(-1);
295 ip6e = __UNCONST(CCMSG_DATA(cmsg));
296 hdrlen = (ip6e->ip6e_len + 1) << 3;
297 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
298 return(-1);
299
300 /*
301 * If the caller does not specify the starting point,
302 * simply return the 1st option.
303 * Otherwise, search the option list for the next option.
304 */
305 lim = (uint8_t *)(void *)ip6e + hdrlen;
306 if (*tptrp == NULL)
307 *tptrp = (uint8_t *)(void *)(ip6e + 1);
308 else {
309 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
310 return(-1);
311
312 *tptrp = *tptrp + optlen;
313 }
314 if (*tptrp >= lim) { /* there is no option */
315 *tptrp = NULL;
316 return(-1);
317 }
318 /*
319 * Finally, checks if the next option is safely stored in the
320 * cmsg data.
321 */
322 if (ip6optlen(*tptrp, lim) == 0)
323 return(-1);
324 else
325 return(0);
326 }
327
328 /*
329 * This function is similar to the inet6_option_next() function,
330 * except this function lets the caller specify the option type to be
331 * searched for, instead of always returning the next option in the
332 * ancillary data object.
333 * Note: RFC 2292 says the type of tptrp is uint8_t *, but we think
334 * it's a typo. The variable should be type of uint8_t **.
335 */
336 int
inet6_option_find(const struct cmsghdr * cmsg,uint8_t ** tptrp,int type)337 inet6_option_find(const struct cmsghdr *cmsg, uint8_t **tptrp, int type)
338 {
339 struct ip6_ext *ip6e;
340 int hdrlen, optlen;
341 uint8_t *optp, *lim;
342
343 _DIAGASSERT(cmsg != NULL);
344 _DIAGASSERT(tptrp != NULL);
345
346 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
347 (cmsg->cmsg_type != IPV6_HOPOPTS &&
348 cmsg->cmsg_type != IPV6_DSTOPTS))
349 return(-1);
350
351 /* message length validation */
352 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
353 return(-1);
354 ip6e = __UNCONST(CCMSG_DATA(cmsg));
355 hdrlen = (ip6e->ip6e_len + 1) << 3;
356 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
357 return(-1);
358
359 /*
360 * If the caller does not specify the starting point,
361 * search from the beginning of the option list.
362 * Otherwise, search from *the next option* of the specified point.
363 */
364 lim = (uint8_t *)(void *)ip6e + hdrlen;
365 if (*tptrp == NULL)
366 *tptrp = (uint8_t *)(void *)(ip6e + 1);
367 else {
368 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
369 return(-1);
370
371 *tptrp = *tptrp + optlen;
372 }
373 for (optp = *tptrp; optp < lim; optp += optlen) {
374 if (*optp == type) {
375 *tptrp = optp;
376 return(0);
377 }
378 if ((optlen = ip6optlen(optp, lim)) == 0)
379 return(-1);
380 }
381
382 /* search failed */
383 *tptrp = NULL;
384 return(-1);
385 }
386
387 /*
388 * Calculate the length of a given IPv6 option. Also checks
389 * if the option is safely stored in user's buffer according to the
390 * calculated length and the limitation of the buffer.
391 */
392 static int
ip6optlen(uint8_t * opt,uint8_t * lim)393 ip6optlen(uint8_t *opt, uint8_t *lim)
394 {
395 int optlen;
396
397 _DIAGASSERT(opt != NULL);
398 _DIAGASSERT(lim != NULL);
399
400 if (*opt == IP6OPT_PAD1)
401 optlen = 1;
402 else {
403 /* is there enough space to store type and len? */
404 if (opt + 2 > lim)
405 return(0);
406 optlen = *(opt + 1) + 2;
407 }
408 if (opt + optlen <= lim)
409 return(optlen);
410
411 return(0);
412 }
413
414 static void
inet6_insert_padopt(uint8_t * p,size_t len)415 inet6_insert_padopt(uint8_t *p, size_t len)
416 {
417
418 _DIAGASSERT(p != NULL);
419
420 switch(len) {
421 case 0:
422 return;
423 case 1:
424 p[0] = IP6OPT_PAD1;
425 return;
426 default:
427 p[0] = IP6OPT_PADN;
428 _DIAGASSERT(__type_fit(uint8_t, len - 2));
429 p[1] = (uint8_t)(len - 2);
430 memset(&p[2], 0, len - 2);
431 return;
432 }
433 }
434
435 /*
436 * The following functions are defined in RFC3542, which is a successor
437 * of RFC2292.
438 */
439
440 int
inet6_opt_init(void * extbuf,socklen_t extlen)441 inet6_opt_init(void *extbuf, socklen_t extlen)
442 {
443 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
444
445 if (ext) {
446 if (extlen == 0 || (extlen % 8))
447 return (-1);
448 ext->ip6e_len = (extlen >> 3) - 1;
449 }
450
451 return (2); /* sizeof the next and the length fields */
452 }
453
454 int
inet6_opt_append(void * extbuf,socklen_t extlen,int offset,uint8_t type,socklen_t len,uint8_t align,void ** databufp)455 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, uint8_t type,
456 socklen_t len, uint8_t align, void **databufp)
457 {
458 int currentlen = offset;
459 size_t padlen = 0;
460
461 /*
462 * The option type must have a value from 2 to 255, inclusive.
463 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
464 */
465 if (type < 2)
466 return (-1);
467
468 /*
469 * The option data length must have a value between 0 and 255,
470 * inclusive, and is the length of the option data that follows.
471 */
472 if (len > 255)
473 return (-1);
474
475 /*
476 * The align parameter must have a value of 1, 2, 4, or 8.
477 * The align value can not exceed the value of len.
478 */
479 if (align != 1 && align != 2 && align != 4 && align != 8)
480 return (-1);
481 if (align > len)
482 return (-1);
483
484 /* Calculate the padding length. */
485 currentlen += 2 + len; /* 2 means "type + len" */
486 if (currentlen % align)
487 padlen = align - (currentlen % align);
488
489 /* The option must fit in the extension header buffer. */
490 _DIAGASSERT(__type_fit(int, currentlen + padlen));
491 currentlen += (int)padlen;
492 if (extlen && /* XXX: right? */
493 (socklen_t)currentlen > extlen)
494 return (-1);
495
496 if (extbuf) {
497 uint8_t *optp = (uint8_t *)extbuf + offset;
498
499 if (padlen == 1) {
500 /* insert a Pad1 option */
501 *optp = IP6OPT_PAD1;
502 optp++;
503 } else if (padlen > 0) {
504 /* insert a PadN option for alignment */
505 *optp++ = IP6OPT_PADN;
506 _DIAGASSERT(__type_fit(uint8_t, padlen - 2));
507 *optp++ = (uint8_t)(padlen - 2);
508 memset(optp, 0, padlen - 2);
509 optp += (padlen - 2);
510 }
511
512 *optp++ = type;
513 *optp++ = len;
514
515 *databufp = optp;
516 }
517
518 return (currentlen);
519 }
520
521 int
inet6_opt_finish(void * extbuf,socklen_t extlen,int offset)522 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
523 {
524 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
525
526 if (extbuf) {
527 uint8_t *padp;
528 size_t padlen = updatelen - offset;
529
530 if ((socklen_t)updatelen > extlen || padlen >= 256 + 2)
531 return (-1);
532
533 padp = (uint8_t *)extbuf + offset;
534 if (padlen == 1)
535 *padp = IP6OPT_PAD1;
536 else if (padlen > 0) {
537 *padp++ = IP6OPT_PADN;
538 *padp++ = (uint8_t)(padlen - 2);
539 memset(padp, 0, padlen - 2);
540 }
541 }
542
543 return (updatelen);
544 }
545
546 int
inet6_opt_set_val(void * databuf,int offset,void * val,socklen_t vallen)547 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
548 {
549
550 memcpy((uint8_t *)databuf + offset, val, vallen);
551 return (offset + vallen);
552 }
553
554 int
inet6_opt_next(void * extbuf,socklen_t extlen,int offset,uint8_t * typep,socklen_t * lenp,void ** databufp)555 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, uint8_t *typep,
556 socklen_t *lenp, void **databufp)
557 {
558 uint8_t *optp, *lim;
559 int optlen;
560
561 /* Validate extlen. XXX: is the variable really necessary?? */
562 if (extlen == 0 || (extlen % 8))
563 return (-1);
564 lim = (uint8_t *)extbuf + extlen;
565
566 /*
567 * If this is the first time this function called for this options
568 * header, simply return the 1st option.
569 * Otherwise, search the option list for the next option.
570 */
571 if (offset == 0)
572 optp = (uint8_t *)(void *)((struct ip6_hbh *)extbuf + 1);
573 else
574 optp = (uint8_t *)extbuf + offset;
575
576 /* Find the next option skipping any padding options. */
577 while (optp < lim) {
578 ptrdiff_t rv;
579 switch(*optp) {
580 case IP6OPT_PAD1:
581 optp++;
582 break;
583 case IP6OPT_PADN:
584 if ((optlen = ip6optlen(optp, lim)) == 0)
585 goto optend;
586 optp += optlen;
587 break;
588 default: /* found */
589 if ((optlen = ip6optlen(optp, lim)) == 0)
590 goto optend;
591 *typep = *optp;
592 *lenp = optlen - 2;
593 *databufp = optp + 2;
594 rv = optp + optlen - (uint8_t *)extbuf;
595 _DIAGASSERT(__type_fit(int, rv));
596 return (int)rv;
597 }
598 }
599
600 optend:
601 *databufp = NULL; /* for safety */
602 return (-1);
603 }
604
605 int
inet6_opt_find(void * extbuf,socklen_t extlen,int offset,uint8_t type,socklen_t * lenp,void ** databufp)606 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, uint8_t type,
607 socklen_t *lenp, void **databufp)
608 {
609 uint8_t *optp, *lim;
610 int optlen;
611
612 /* Validate extlen. XXX: is the variable really necessary?? */
613 if (extlen == 0 || (extlen % 8))
614 return (-1);
615 lim = (uint8_t *)extbuf + extlen;
616
617 /*
618 * If this is the first time this function called for this options
619 * header, simply return the 1st option.
620 * Otherwise, search the option list for the next option.
621 */
622 if (offset == 0)
623 optp = (uint8_t *)(void *)((struct ip6_hbh *)extbuf + 1);
624 else
625 optp = (uint8_t *)extbuf + offset;
626
627 /* Find the specified option */
628 while (optp < lim) {
629 if ((optlen = ip6optlen(optp, lim)) == 0)
630 goto optend;
631
632 if (*optp == type) { /* found */
633 ptrdiff_t td;
634 *lenp = optlen - 2;
635 *databufp = optp + 2;
636 td = optp + optlen - (uint8_t *)extbuf;
637 _DIAGASSERT(__type_fit(int, td));
638 return (int)td;
639 }
640
641 optp += optlen;
642 }
643
644 optend:
645 *databufp = NULL; /* for safety */
646 return (-1);
647 }
648
649 int
inet6_opt_get_val(void * databuf,int offset,void * val,socklen_t vallen)650 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
651 {
652
653 /* we can't assume alignment here */
654 memcpy(val, (uint8_t *)databuf + offset, vallen);
655
656 return (offset + vallen);
657 }
658