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1 /*

3 */

4 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */

6 /*

9 *

10 * Redistribution and use in source and binary forms, with or without

11 * modification, are permitted provided that the following conditions

12 * are met:

13 * 1. Redistributions of source code must retain the above copyright

14 * notice, this list of conditions and the following disclaimer.

15 * 2. Redistributions in binary form must reproduce the above copyright

16 * notice, this list of conditions and the following disclaimer in the

17 * documentation and/or other materials provided with the distribution.

18 * 3. Neither the name of the project nor the names of its contributors

19 * may be used to endorse or promote products derived from this software

20 * without specific prior written permission.

21 *

22 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND

23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

25 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE

26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

32 * SUCH DAMAGE.

33 *

34 * $FreeBSD: src/lib/libc/net/ip6opt.c,v 1.8.10.2.2.1 2010/06/14 02:09:06 kensmith Exp $

35 */

37 #include "libinfo_common.h"

39 /*

40 * These routines support RFC 3542

41 * __APPLE_USE_RFC_3542 selects the appropriate API in <netinet6/in6.h>

42 */

43 #define __APPLE_USE_RFC_3542

45 #include <sys/cdefs.h>

47 #include <sys/param.h>

48 #include <sys/types.h>

49 #include <sys/socket.h>

51 #include <netinet/in.h>

52 #include <netinet/ip6.h>

54 #include <string.h>

55 #include <stdio.h>

 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);

 static void inet6_insert_padopt(u_char *p, int len);

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 LIBINFO_EXPORT

70 int

71 inet6_option_space(int nbytes)

72 {

73 nbytes += 2; /* we need space for nxt-hdr and length fields */

         return(CMSG_SPACE((nbytes + 7) & ~7));

75 }

77 /*

78 * This function is called once per ancillary data object that will

79 * contain either Hop-by-Hop or Destination options. It returns 0 on

80 * success or -1 on an error.

81 */

82 LIBINFO_EXPORT

83 int

 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)

85 {

         struct cmsghdr *ch = (struct cmsghdr *)bp;

88 /* argument validation */

         if (type != IPV6_HOPOPTS && type != IPV6_DSTOPTS)

90 return(-1);

92 ch->cmsg_level = IPPROTO_IPV6;

93 ch->cmsg_type = type;

         ch->cmsg_len = CMSG_LEN(0);

96 *cmsgp = ch;

97 return(0);

98 }

100 /*

101 * This function appends a Hop-by-Hop option or a Destination option

102 * into an ancillary data object that has been initialized by

103 * inet6_option_init(). This function returns 0 if it succeeds or -1 on

104 * an error.

105 * multx is the value x in the alignment term "xn + y" described

106 * earlier. It must have a value of 1, 2, 4, or 8.

107 * plusy is the value y in the alignment term "xn + y" described

108 * earlier. It must have a value between 0 and 7, inclusive.

109 */

110 LIBINFO_EXPORT

111 int

 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,

113 int plusy)

114 {

115 int padlen, optlen, off;

         u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;

         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);

118

119 /* argument validation */

         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)

121 return(-1);

         if (plusy < 0 || plusy > 7)

123 return(-1);

124

125 /*

126 * If this is the first option, allocate space for the

127 * first 2 bytes(for next header and length fields) of

128 * the option header.

129 */

         if (bp == (u_char *)eh) {

131 bp += 2;

132 cmsg->cmsg_len += 2;

133 }

134

135 /* calculate pad length before the option. */

136 off = bp - (u_char *)eh;

         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -

138 (off % multx);

139 padlen += plusy;

140 padlen %= multx; /* keep the pad as short as possible */

141 /* insert padding */

142 inet6_insert_padopt(bp, padlen);

143 cmsg->cmsg_len += padlen;

144 bp += padlen;

145

146 /* copy the option */

         if (typep[0] == IP6OPT_PAD1)

148 optlen = 1;

149 else

                 optlen = typep[1] + 2;

         memcpy(bp, typep, optlen);

152 bp += optlen;

153 cmsg->cmsg_len += optlen;

154

155 /* calculate pad length after the option and insert the padding */

156 off = bp - (u_char *)eh;

         padlen = ((off + 7) & ~7) - off;

158 inet6_insert_padopt(bp, padlen);

159 bp += padlen;

160 cmsg->cmsg_len += padlen;

161

162 /* update the length field of the ip6 option header */

         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;

164

165 return(0);

166 }

167

168 /*

169 * This function appends a Hop-by-Hop option or a Destination option

170 * into an ancillary data object that has been initialized by

171 * inet6_option_init(). This function returns a pointer to the 8-bit

172 * option type field that starts the option on success, or NULL on an

173 * error.

174 * The difference between this function and inet6_option_append() is

175 * that the latter copies the contents of a previously built option into

176 * the ancillary data object while the current function returns a

177 * pointer to the space in the data object where the option's TLV must

178 * then be built by the caller.

179 *

180 */

181 LIBINFO_EXPORT

182 u_int8_t *

 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)

184 {

185 int padlen, off;

         u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;

187 u_int8_t *retval;

         struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);

189

190 /* argument validation */

         if (multx != 1 && multx != 2 && multx != 4 && multx != 8)

192 return(NULL);

         if (plusy < 0 || plusy > 7)

194 return(NULL);

195

196 /*

197 * If this is the first option, allocate space for the

198 * first 2 bytes(for next header and length fields) of

199 * the option header.

200 */

         if (bp == (u_char *)eh) {

202 bp += 2;

203 cmsg->cmsg_len += 2;

204 }

205

206 /* calculate pad length before the option. */

207 off = bp - (u_char *)eh;

         padlen = (((off % multx) + (multx - 1)) & ~(multx - 1)) -

209 (off % multx);

210 padlen += plusy;

211 padlen %= multx; /* keep the pad as short as possible */

212 /* insert padding */

213 inet6_insert_padopt(bp, padlen);

214 cmsg->cmsg_len += padlen;

215 bp += padlen;

216

217 /* keep space to store specified length of data */

218 retval = bp;

219 bp += datalen;

220 cmsg->cmsg_len += datalen;

221

222 /* calculate pad length after the option and insert the padding */

223 off = bp - (u_char *)eh;

         padlen = ((off + 7) & ~7) - off;

225 inet6_insert_padopt(bp, padlen);

226 bp += padlen;

227 cmsg->cmsg_len += padlen;

228

229 /* update the length field of the ip6 option header */

         eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;

231

232 return(retval);

233 }

234

235 /*

236 * This function processes the next Hop-by-Hop option or Destination

237 * option in an ancillary data object. If another option remains to be

238 * processed, the return value of the function is 0 and *tptrp points to

239 * the 8-bit option type field (which is followed by the 8-bit option

240 * data length, followed by the option data). If no more options remain

241 * to be processed, the return value is -1 and *tptrp is NULL. If an

242 * error occurs, the return value is -1 and *tptrp is not NULL.

243 * (RFC 2292, 6.3.5)

244 */

245 LIBINFO_EXPORT

246 int

 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)

248 {

249 struct ip6_ext *ip6e;

250 int hdrlen, optlen;

251 u_int8_t *lim;

252

         if (cmsg->cmsg_level != IPPROTO_IPV6 ||

254 (cmsg->cmsg_type != IPV6_HOPOPTS &&

255 cmsg->cmsg_type != IPV6_DSTOPTS))

256 return(-1);

257

258 /* message length validation */

         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))

260 return(-1);

         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);

         hdrlen = (ip6e->ip6e_len + 1) << 3;

         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))

264 return(-1);

265

266 /*

267 * If the caller does not specify the starting point,

268 * simply return the 1st option.

269 * Otherwise, search the option list for the next option.

270 */

271 lim = (u_int8_t *)ip6e + hdrlen;

272 if (*tptrp == NULL)

                 *tptrp = (u_int8_t *)(ip6e + 1);

274 else {

                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)

276 return(-1);

277

278 *tptrp = *tptrp + optlen;

279 }

         if (*tptrp >= lim) {    /* there is no option */

281 *tptrp = NULL;

282 return(-1);

283 }

284 /*

285 * Finally, checks if the next option is safely stored in the

286 * cmsg data.

287 */

         if (ip6optlen(*tptrp, lim) == 0)

289 return(-1);

290 else

291 return(0);

292 }

293

294 /*

295 * This function is similar to the inet6_option_next() function,

296 * except this function lets the caller specify the option type to be

297 * searched for, instead of always returning the next option in the

298 * ancillary data object.

299 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think

300 * it's a typo. The variable should be type of u_int8_t **.

301 */

302 LIBINFO_EXPORT

303 int

 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)

305 {

306 struct ip6_ext *ip6e;

307 int hdrlen, optlen;

308 u_int8_t *optp, *lim;

309

         if (cmsg->cmsg_level != IPPROTO_IPV6 ||

311 (cmsg->cmsg_type != IPV6_HOPOPTS &&

312 cmsg->cmsg_type != IPV6_DSTOPTS))

313 return(-1);

314

315 /* message length validation */

         if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))

317 return(-1);

         ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);

         hdrlen = (ip6e->ip6e_len + 1) << 3;

         if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))

321 return(-1);

322

323 /*

324 * If the caller does not specify the starting point,

325 * search from the beginning of the option list.

326 * Otherwise, search from *the next option* of the specified point.

327 */

328 lim = (u_int8_t *)ip6e + hdrlen;

329 if (*tptrp == NULL)

                 *tptrp = (u_int8_t *)(ip6e + 1);

331 else {

                 if ((optlen = ip6optlen(*tptrp, lim)) == 0)

333 return(-1);

334

335 *tptrp = *tptrp + optlen;

336 }

         for (optp = *tptrp; optp < lim; optp += optlen) {

338 if (*optp == type) {

339 *tptrp = optp;

340 return(0);

341 }

                 if ((optlen = ip6optlen(optp, lim)) == 0)

343 return(-1);

344 }

345

346 /* search failed */

347 *tptrp = NULL;

348 return(-1);

349 }

350

351 /*

352 * Calculate the length of a given IPv6 option. Also checks

353 * if the option is safely stored in user's buffer according to the

354 * calculated length and the limitation of the buffer.

355 */

356 static int

 ip6optlen(u_int8_t *opt, u_int8_t *lim)

358 {

359 int optlen;

360

361 if (*opt == IP6OPT_PAD1)

362 optlen = 1;

363 else {

364 /* is there enough space to store type and len? */

                 if (opt + 2 > lim)

366 return(0);

                 optlen = *(opt + 1) + 2;

368 }

         if (opt + optlen <= lim)

370 return(optlen);

371

372 return(0);

373 }

374

375 static void

 inet6_insert_padopt(u_char *p, int len)

377 {

378 switch(len) {

379 case 0:

380 return;

381 case 1:

382 p[0] = IP6OPT_PAD1;

383 return;

384 default:

385 p[0] = IP6OPT_PADN;

                  p[1] = len - 2; 

                  memset(&p[2], 0, len - 2);

388 return;

389 }

390 }

391

392 /*

393 * The following functions are defined in RFC3542, which is a successor

394 * of RFC2292.

395 */

396

397 LIBINFO_EXPORT

398 int

 inet6_opt_init(void *extbuf, socklen_t extlen)

400 {

         struct ip6_ext *ext = (struct ip6_ext *)extbuf;

402

         if (extlen == 0 || (extlen % 8)) {

404 return(-1);

405 }

406

407 if (ext) {

                 ext->ip6e_len = (extlen >> 3) - 1;

409 }

410

         return(2);              /* sizeof the next and the length fields */

412 }

413

414 LIBINFO_EXPORT

415 int

 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type, socklen_t len, u_int8_t align, void **databufp)

417 {

         int currentlen = offset, padlen = 0;

419

420 /*

421 * The option type must have a value from 2 to 255, inclusive.

422 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)

423 */

         if (type < 2)

425 return(-1);

426

427 /*

428 * The option data length must have a value between 0 and 255,

429 * inclusive, and is the length of the option data that follows.

430 */

         if (len > 255) {

432 return(-1);

433 }

434

435 /*

436 * The align parameter must have a value of 1, 2, 4, or 8.

437 * The align value can not exceed the value of len.

438 */

         if (align != 1 && align != 2 && align != 4 && align != 8)

440 return(-1);

441 if (align > len)

442 return(-1);

443

444 /* Calculate the padding length. */

         currentlen += 2 + len;  /* 2 means "type + len" */

446 if (currentlen % align)

447 padlen = align - (currentlen % align);

448

449 /* The option must fit in the extension header buffer. */

450 currentlen += padlen;

451 if (extlen && /* XXX: right? */

452 currentlen > extlen)

453 return(-1);

454

455 if (extbuf) {

                 u_int8_t *optp = (u_int8_t *)extbuf + offset;

457

                 if (padlen == 1) {

459 /* insert a Pad1 option */

460 *optp = IP6OPT_PAD1;

461 optp++;

462 }

                 else if (padlen > 0) {

464 /* insert a PadN option for alignment */

465 *optp++ = IP6OPT_PADN;

                         *optp++ = padlen - 2;

                         memset(optp, 0, padlen - 2);

468 optp += (padlen - 2);

469 }

470

471 *optp++ = type;

472 *optp++ = len;

473

474 *databufp = optp;

475 }

476

477 return(currentlen);

478 }

479

480 LIBINFO_EXPORT

481 int

 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)

483 {

         int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;;

485

486 if (extbuf) {

487 u_int8_t *padp;

488 int padlen = updatelen - offset;

489

490 if (updatelen > extlen)

491 return(-1);

492

493 padp = (u_int8_t *)extbuf + offset;

                 if (padlen == 1)

495 *padp = IP6OPT_PAD1;

                 else if (padlen > 0) {

497 *padp++ = IP6OPT_PADN;

                         *padp++ = (padlen - 2);

                         memset(padp, 0, padlen - 2);

500 }

501 }

502

503 return(updatelen);

504 }

505

506 LIBINFO_EXPORT

507 int

 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)

509 {

         memcpy((u_int8_t *)databuf + offset, val, vallen);

511 return(offset + vallen);

512 }

513

514 LIBINFO_EXPORT

515 int

 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep, socklen_t *lenp, void **databufp)

517 {

518 u_int8_t *optp, *lim;

519 int optlen;

520

521 /* Validate extlen. XXX: is the variable really necessary?? */

         if (extlen == 0 || (extlen % 8))

523 return(-1);

524 lim = (u_int8_t *)extbuf + extlen;

525

526 /*

527 * If this is the first time this function called for this options

528 * header, simply return the 1st option.

529 * Otherwise, search the option list for the next option.

530 */

         if (offset == 0) {

                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);

533 }

534 else

535 optp = (u_int8_t *)extbuf + offset;

536

537 /* Find the next option skipping any padding options. */

538 while(optp < lim) {

539 switch(*optp) {

540 case IP6OPT_PAD1:

541 optp++;

542 break;

543 case IP6OPT_PADN:

                         if ((optlen = ip6optlen(optp, lim)) == 0)

545 goto optend;

546 optp += optlen;

547 break;

548 default: /* found */

                         if ((optlen = ip6optlen(optp, lim)) == 0)

550 goto optend;

551 *typep = *optp;

                         *lenp = optlen - 2;

                         *databufp = optp + 2;

                         return(optp + optlen - (u_int8_t *)extbuf);

555 }

556 }

557

558 optend:

559 *databufp = NULL; /* for safety */

560 return(-1);

561 }

562

563 LIBINFO_EXPORT

564 int

 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type, socklen_t *lenp, void **databufp)

566 {

567 u_int8_t *optp, *lim;

568 int optlen;

569

570 /* Validate extlen. XXX: is the variable really necessary?? */

         if (extlen == 0 || (extlen % 8))

572 return(-1);

573 lim = (u_int8_t *)extbuf + extlen;

574

575 /*

576 * If this is the first time this function called for this options

577 * header, simply return the 1st option.

578 * Otherwise, search the option list for the next option.

579 */

         if (offset == 0) {

                 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);

582 }

583 else

584 optp = (u_int8_t *)extbuf + offset;

585

586 /* Find the specified option */

587 while(optp < lim) {

                 if ((optlen = ip6optlen(optp, lim)) == 0)

589 goto optend;

590

                 if (*optp == type) { /* found */

                         *lenp = optlen - 2;

                         *databufp = optp + 2;

                         return(optp + optlen - (u_int8_t *)extbuf);

595 }

596

597 optp += optlen;

598 }

599

600 optend:

601 *databufp = NULL; /* for safety */

602 return(-1);

603 }

604

605 LIBINFO_EXPORT

606 int

 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)

608 {

609 /* we can't assume alignment here */

         memcpy(val, (u_int8_t *)databuf + offset, vallen);

611

612 return(offset + vallen);

613 }