1 /* $FreeBSD: head/lib/libusb/libusb20_desc.c 248236 2013-03-13 12:23:14Z hselasky $ */ 2 /*- 3 * Copyright (c) 2008 Hans Petter Selasky. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #ifdef LIBUSB_GLOBAL_INCLUDE_FILE 28 #include LIBUSB_GLOBAL_INCLUDE_FILE 29 #else 30 #include <stdio.h> 31 #include <stdlib.h> 32 #include <string.h> 33 #include <time.h> 34 #include <sys/queue.h> 35 #endif 36 37 #include "libusb20.h" 38 #include "libusb20_desc.h" 39 #include "libusb20_int.h" 40 41 static const uint32_t libusb20_me_encode_empty[2]; /* dummy */ 42 43 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_DEVICE_DESC); 44 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_ENDPOINT_DESC); 45 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_INTERFACE_DESC); 46 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONFIG_DESC); 47 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONTROL_SETUP); 48 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_ENDPT_COMP_DESC); 49 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_USB_20_DEVCAP_DESC); 50 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_USB_DEVCAP_DESC); 51 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_BOS_DESCRIPTOR); 52 53 /*------------------------------------------------------------------------* 54 * libusb20_parse_config_desc 55 * 56 * Return values: 57 * NULL: Out of memory. 58 * Else: A valid config structure pointer which must be passed to "free()" 59 *------------------------------------------------------------------------*/ 60 struct libusb20_config * 61 libusb20_parse_config_desc(const void *config_desc) 62 { 63 struct libusb20_config *lub_config; 64 struct libusb20_interface *lub_interface; 65 struct libusb20_interface *lub_alt_interface; 66 struct libusb20_interface *last_if; 67 struct libusb20_endpoint *lub_endpoint; 68 struct libusb20_endpoint *last_ep; 69 70 struct libusb20_me_struct pcdesc; 71 const uint8_t *ptr; 72 uint32_t size; 73 uint16_t niface_no_alt; 74 uint16_t niface; 75 uint16_t nendpoint; 76 uint16_t iface_no; 77 78 ptr = config_desc; 79 if (ptr[1] != LIBUSB20_DT_CONFIG) { 80 return (NULL); /* not config descriptor */ 81 } 82 /* 83 * The first "bInterfaceNumber" should never have the value 0xff. 84 * Then it is corrupt. 85 */ 86 niface_no_alt = 0; 87 nendpoint = 0; 88 niface = 0; 89 iface_no = 0xFFFF; 90 ptr = NULL; 91 92 /* get "wTotalLength" and setup "pcdesc" */ 93 pcdesc.ptr = LIBUSB20_ADD_BYTES(config_desc, 0); 94 pcdesc.len = 95 ((const uint8_t *)config_desc)[2] | 96 (((const uint8_t *)config_desc)[3] << 8); 97 pcdesc.type = LIBUSB20_ME_IS_RAW; 98 99 /* descriptor pre-scan */ 100 while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) { 101 if (ptr[1] == LIBUSB20_DT_ENDPOINT) { 102 nendpoint++; 103 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) { 104 niface++; 105 /* check "bInterfaceNumber" */ 106 if (ptr[2] != iface_no) { 107 iface_no = ptr[2]; 108 niface_no_alt++; 109 } 110 } 111 } 112 113 /* sanity checking */ 114 if (niface >= 256) { 115 return (NULL); /* corrupt */ 116 } 117 if (nendpoint >= 256) { 118 return (NULL); /* corrupt */ 119 } 120 size = sizeof(*lub_config) + 121 (niface * sizeof(*lub_interface)) + 122 (nendpoint * sizeof(*lub_endpoint)) + 123 pcdesc.len; 124 125 lub_config = malloc(size); 126 if (lub_config == NULL) { 127 return (NULL); /* out of memory */ 128 } 129 /* make sure memory is initialised */ 130 memset(lub_config, 0, size); 131 132 lub_interface = (void *)(lub_config + 1); 133 lub_alt_interface = (void *)(lub_interface + niface_no_alt); 134 lub_endpoint = (void *)(lub_interface + niface); 135 136 /* 137 * Make a copy of the config descriptor, so that the caller can free 138 * the inital config descriptor pointer! 139 */ 140 ptr = (void *)(lub_endpoint + nendpoint); 141 memcpy(LIBUSB20_ADD_BYTES(ptr, 0), config_desc, pcdesc.len); 142 pcdesc.ptr = LIBUSB20_ADD_BYTES(ptr, 0); 143 config_desc = LIBUSB20_ADD_BYTES(ptr, 0); 144 145 /* init config structure */ 146 147 ptr = config_desc; 148 149 LIBUSB20_INIT(LIBUSB20_CONFIG_DESC, &lub_config->desc); 150 151 if (libusb20_me_decode(ptr, ptr[0], &lub_config->desc)) { 152 /* ignore */ 153 } 154 lub_config->num_interface = 0; 155 lub_config->interface = lub_interface; 156 lub_config->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); 157 lub_config->extra.len = -ptr[0]; 158 lub_config->extra.type = LIBUSB20_ME_IS_RAW; 159 160 /* reset states */ 161 niface = 0; 162 iface_no = 0xFFFF; 163 ptr = NULL; 164 lub_interface--; 165 lub_endpoint--; 166 last_if = NULL; 167 last_ep = NULL; 168 169 /* descriptor pre-scan */ 170 while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) { 171 if (ptr[1] == LIBUSB20_DT_ENDPOINT) { 172 if (last_if) { 173 lub_endpoint++; 174 last_ep = lub_endpoint; 175 last_if->num_endpoints++; 176 177 LIBUSB20_INIT(LIBUSB20_ENDPOINT_DESC, &last_ep->desc); 178 179 if (libusb20_me_decode(ptr, ptr[0], &last_ep->desc)) { 180 /* ignore */ 181 } 182 last_ep->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); 183 last_ep->extra.len = 0; 184 last_ep->extra.type = LIBUSB20_ME_IS_RAW; 185 } else { 186 lub_config->extra.len += ptr[0]; 187 } 188 189 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) { 190 if (ptr[2] != iface_no) { 191 /* new interface */ 192 iface_no = ptr[2]; 193 lub_interface++; 194 lub_config->num_interface++; 195 last_if = lub_interface; 196 niface++; 197 } else { 198 /* one more alternate setting */ 199 lub_interface->num_altsetting++; 200 last_if = lub_alt_interface; 201 lub_alt_interface++; 202 } 203 204 LIBUSB20_INIT(LIBUSB20_INTERFACE_DESC, &last_if->desc); 205 206 if (libusb20_me_decode(ptr, ptr[0], &last_if->desc)) { 207 /* ignore */ 208 } 209 /* 210 * Sometimes USB devices have corrupt interface 211 * descriptors and we need to overwrite the provided 212 * interface number! 213 */ 214 last_if->desc.bInterfaceNumber = niface - 1; 215 last_if->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); 216 last_if->extra.len = 0; 217 last_if->extra.type = LIBUSB20_ME_IS_RAW; 218 last_if->endpoints = lub_endpoint + 1; 219 last_if->altsetting = lub_alt_interface; 220 last_if->num_altsetting = 0; 221 last_if->num_endpoints = 0; 222 last_ep = NULL; 223 } else { 224 /* unknown descriptor */ 225 if (last_if) { 226 if (last_ep) { 227 last_ep->extra.len += ptr[0]; 228 } else { 229 last_if->extra.len += ptr[0]; 230 } 231 } else { 232 lub_config->extra.len += ptr[0]; 233 } 234 } 235 } 236 return (lub_config); 237 } 238 239 /*------------------------------------------------------------------------* 240 * libusb20_desc_foreach 241 * 242 * Safe traversal of USB descriptors. 243 * 244 * Return values: 245 * NULL: End of descriptors 246 * Else: Pointer to next descriptor 247 *------------------------------------------------------------------------*/ 248 const uint8_t * 249 libusb20_desc_foreach(const struct libusb20_me_struct *pdesc, 250 const uint8_t *psubdesc) 251 { 252 const uint8_t *start; 253 const uint8_t *end; 254 const uint8_t *desc_next; 255 256 /* be NULL safe */ 257 if (pdesc == NULL) 258 return (NULL); 259 260 start = (const uint8_t *)pdesc->ptr; 261 end = LIBUSB20_ADD_BYTES(start, pdesc->len); 262 263 /* get start of next descriptor */ 264 if (psubdesc == NULL) 265 psubdesc = start; 266 else 267 psubdesc = psubdesc + psubdesc[0]; 268 269 /* check that the next USB descriptor is within the range */ 270 if ((psubdesc < start) || (psubdesc >= end)) 271 return (NULL); /* out of range, or EOD */ 272 273 /* check start of the second next USB descriptor, if any */ 274 desc_next = psubdesc + psubdesc[0]; 275 if ((desc_next < start) || (desc_next > end)) 276 return (NULL); /* out of range */ 277 278 /* check minimum descriptor length */ 279 if (psubdesc[0] < 3) 280 return (NULL); /* too short descriptor */ 281 282 return (psubdesc); /* return start of next descriptor */ 283 } 284 285 /*------------------------------------------------------------------------* 286 * libusb20_me_get_1 - safety wrapper to read out one byte 287 *------------------------------------------------------------------------*/ 288 uint8_t 289 libusb20_me_get_1(const struct libusb20_me_struct *ie, uint16_t offset) 290 { 291 if (offset < ie->len) { 292 return (*((uint8_t *)LIBUSB20_ADD_BYTES(ie->ptr, offset))); 293 } 294 return (0); 295 } 296 297 /*------------------------------------------------------------------------* 298 * libusb20_me_get_2 - safety wrapper to read out one word 299 *------------------------------------------------------------------------*/ 300 uint16_t 301 libusb20_me_get_2(const struct libusb20_me_struct *ie, uint16_t offset) 302 { 303 return (libusb20_me_get_1(ie, offset) | 304 (libusb20_me_get_1(ie, offset + 1) << 8)); 305 } 306 307 /*------------------------------------------------------------------------* 308 * libusb20_me_encode - encode a message structure 309 * 310 * Description of parameters: 311 * "len" - maximum length of output buffer 312 * "ptr" - pointer to output buffer. If NULL, no data will be written 313 * "pd" - source structure 314 * 315 * Return values: 316 * 0..65535 - Number of bytes used, limited by the "len" input parameter. 317 *------------------------------------------------------------------------*/ 318 uint16_t 319 libusb20_me_encode(void *ptr, uint16_t len, const void *pd) 320 { 321 const uint8_t *pf; /* pointer to format data */ 322 uint8_t *buf; /* pointer to output buffer */ 323 324 uint32_t pd_offset; /* decoded structure offset */ 325 uint16_t len_old; /* old length */ 326 uint16_t pd_count; /* decoded element count */ 327 uint8_t me; /* message element */ 328 329 /* initialise */ 330 331 len_old = len; 332 buf = ptr; 333 pd_offset = sizeof(void *); 334 pf = (*((struct libusb20_me_format *const *)pd))->format; 335 336 /* scan */ 337 338 while (1) { 339 340 /* get information element */ 341 342 me = (pf[0]) & LIBUSB20_ME_MASK; 343 pd_count = pf[1] | (pf[2] << 8); 344 pf += 3; 345 346 /* encode the message element */ 347 348 switch (me) { 349 case LIBUSB20_ME_INT8: 350 while (pd_count--) { 351 uint8_t temp; 352 353 if (len < 1) /* overflow */ 354 goto done; 355 if (buf) { 356 temp = *((const uint8_t *) 357 LIBUSB20_ADD_BYTES(pd, pd_offset)); 358 buf[0] = temp; 359 buf += 1; 360 } 361 pd_offset += 1; 362 len -= 1; 363 } 364 break; 365 366 case LIBUSB20_ME_INT16: 367 pd_offset = -((-pd_offset) & ~1); /* align */ 368 while (pd_count--) { 369 uint16_t temp; 370 371 if (len < 2) /* overflow */ 372 goto done; 373 374 if (buf) { 375 temp = *((const uint16_t *) 376 LIBUSB20_ADD_BYTES(pd, pd_offset)); 377 buf[1] = (temp >> 8) & 0xFF; 378 buf[0] = temp & 0xFF; 379 buf += 2; 380 } 381 pd_offset += 2; 382 len -= 2; 383 } 384 break; 385 386 case LIBUSB20_ME_INT32: 387 pd_offset = -((-pd_offset) & ~3); /* align */ 388 while (pd_count--) { 389 uint32_t temp; 390 391 if (len < 4) /* overflow */ 392 goto done; 393 if (buf) { 394 temp = *((const uint32_t *) 395 LIBUSB20_ADD_BYTES(pd, pd_offset)); 396 buf[3] = (temp >> 24) & 0xFF; 397 buf[2] = (temp >> 16) & 0xFF; 398 buf[1] = (temp >> 8) & 0xFF; 399 buf[0] = temp & 0xFF; 400 buf += 4; 401 } 402 pd_offset += 4; 403 len -= 4; 404 } 405 break; 406 407 case LIBUSB20_ME_INT64: 408 pd_offset = -((-pd_offset) & ~7); /* align */ 409 while (pd_count--) { 410 uint64_t temp; 411 412 if (len < 8) /* overflow */ 413 goto done; 414 if (buf) { 415 416 temp = *((const uint64_t *) 417 LIBUSB20_ADD_BYTES(pd, pd_offset)); 418 buf[7] = (temp >> 56) & 0xFF; 419 buf[6] = (temp >> 48) & 0xFF; 420 buf[5] = (temp >> 40) & 0xFF; 421 buf[4] = (temp >> 32) & 0xFF; 422 buf[3] = (temp >> 24) & 0xFF; 423 buf[2] = (temp >> 16) & 0xFF; 424 buf[1] = (temp >> 8) & 0xFF; 425 buf[0] = temp & 0xFF; 426 buf += 8; 427 } 428 pd_offset += 8; 429 len -= 8; 430 } 431 break; 432 433 case LIBUSB20_ME_STRUCT: 434 pd_offset = -((-pd_offset) & 435 ~(LIBUSB20_ME_STRUCT_ALIGN - 1)); /* align */ 436 while (pd_count--) { 437 void *src_ptr; 438 uint16_t src_len; 439 struct libusb20_me_struct *ps; 440 441 ps = LIBUSB20_ADD_BYTES(pd, pd_offset); 442 443 switch (ps->type) { 444 case LIBUSB20_ME_IS_RAW: 445 src_len = ps->len; 446 src_ptr = ps->ptr; 447 break; 448 449 case LIBUSB20_ME_IS_ENCODED: 450 if (ps->len == 0) { 451 /* 452 * Length is encoded 453 * in the data itself 454 * and should be 455 * correct: 456 */ 457 ps->len = 0xFFFF; 458 } 459 src_len = libusb20_me_get_1(pd, 0); 460 src_ptr = LIBUSB20_ADD_BYTES(ps->ptr, 1); 461 if (src_len == 0xFF) { 462 /* length is escaped */ 463 src_len = libusb20_me_get_2(pd, 1); 464 src_ptr = 465 LIBUSB20_ADD_BYTES(ps->ptr, 3); 466 } 467 break; 468 469 case LIBUSB20_ME_IS_DECODED: 470 /* reserve 3 length bytes */ 471 src_len = libusb20_me_encode(NULL, 472 0xFFFF - 3, ps->ptr); 473 src_ptr = NULL; 474 break; 475 476 default: /* empty structure */ 477 src_len = 0; 478 src_ptr = NULL; 479 break; 480 } 481 482 if (src_len > 0xFE) { 483 if (src_len > (0xFFFF - 3)) 484 /* overflow */ 485 goto done; 486 487 if (len < (src_len + 3)) 488 /* overflow */ 489 goto done; 490 491 if (buf) { 492 buf[0] = 0xFF; 493 buf[1] = (src_len & 0xFF); 494 buf[2] = (src_len >> 8) & 0xFF; 495 buf += 3; 496 } 497 len -= (src_len + 3); 498 } else { 499 if (len < (src_len + 1)) 500 /* overflow */ 501 goto done; 502 503 if (buf) { 504 buf[0] = (src_len & 0xFF); 505 buf += 1; 506 } 507 len -= (src_len + 1); 508 } 509 510 /* check for buffer and non-zero length */ 511 512 if (buf && src_len) { 513 if (ps->type == LIBUSB20_ME_IS_DECODED) { 514 /* 515 * Repeat encode 516 * procedure - we have 517 * room for the 518 * complete structure: 519 */ 520 uint16_t dummy; 521 522 dummy = libusb20_me_encode(buf, 523 0xFFFF - 3, ps->ptr); 524 } else { 525 bcopy(src_ptr, buf, src_len); 526 } 527 buf += src_len; 528 } 529 pd_offset += sizeof(struct libusb20_me_struct); 530 } 531 break; 532 533 default: 534 goto done; 535 } 536 } 537 done: 538 return (len_old - len); 539 } 540 541 /*------------------------------------------------------------------------* 542 * libusb20_me_decode - decode a message into a decoded structure 543 * 544 * Description of parameters: 545 * "ptr" - message pointer 546 * "len" - message length 547 * "pd" - pointer to decoded structure 548 * 549 * Returns: 550 * "0..65535" - number of bytes decoded, limited by "len" 551 *------------------------------------------------------------------------*/ 552 uint16_t 553 libusb20_me_decode(const void *ptr, uint16_t len, void *pd) 554 { 555 const uint8_t *pf; /* pointer to format data */ 556 const uint8_t *buf; /* pointer to input buffer */ 557 558 uint32_t pd_offset; /* decoded structure offset */ 559 uint16_t len_old; /* old length */ 560 uint16_t pd_count; /* decoded element count */ 561 uint8_t me; /* message element */ 562 563 /* initialise */ 564 565 len_old = len; 566 buf = ptr; 567 pd_offset = sizeof(void *); 568 pf = (*((struct libusb20_me_format **)pd))->format; 569 570 /* scan */ 571 572 while (1) { 573 574 /* get information element */ 575 576 me = (pf[0]) & LIBUSB20_ME_MASK; 577 pd_count = pf[1] | (pf[2] << 8); 578 pf += 3; 579 580 /* decode the message element by type */ 581 582 switch (me) { 583 case LIBUSB20_ME_INT8: 584 while (pd_count--) { 585 uint8_t temp; 586 587 if (len < 1) { 588 len = 0; 589 temp = 0; 590 } else { 591 len -= 1; 592 temp = buf[0]; 593 buf++; 594 } 595 *((uint8_t *)LIBUSB20_ADD_BYTES(pd, 596 pd_offset)) = temp; 597 pd_offset += 1; 598 } 599 break; 600 601 case LIBUSB20_ME_INT16: 602 pd_offset = -((-pd_offset) & ~1); /* align */ 603 while (pd_count--) { 604 uint16_t temp; 605 606 if (len < 2) { 607 len = 0; 608 temp = 0; 609 } else { 610 len -= 2; 611 temp = buf[1] << 8; 612 temp |= buf[0]; 613 buf += 2; 614 } 615 *((uint16_t *)LIBUSB20_ADD_BYTES(pd, 616 pd_offset)) = temp; 617 pd_offset += 2; 618 } 619 break; 620 621 case LIBUSB20_ME_INT32: 622 pd_offset = -((-pd_offset) & ~3); /* align */ 623 while (pd_count--) { 624 uint32_t temp; 625 626 if (len < 4) { 627 len = 0; 628 temp = 0; 629 } else { 630 len -= 4; 631 temp = buf[3] << 24; 632 temp |= buf[2] << 16; 633 temp |= buf[1] << 8; 634 temp |= buf[0]; 635 buf += 4; 636 } 637 638 *((uint32_t *)LIBUSB20_ADD_BYTES(pd, 639 pd_offset)) = temp; 640 pd_offset += 4; 641 } 642 break; 643 644 case LIBUSB20_ME_INT64: 645 pd_offset = -((-pd_offset) & ~7); /* align */ 646 while (pd_count--) { 647 uint64_t temp; 648 649 if (len < 8) { 650 len = 0; 651 temp = 0; 652 } else { 653 len -= 8; 654 temp = ((uint64_t)buf[7]) << 56; 655 temp |= ((uint64_t)buf[6]) << 48; 656 temp |= ((uint64_t)buf[5]) << 40; 657 temp |= ((uint64_t)buf[4]) << 32; 658 temp |= buf[3] << 24; 659 temp |= buf[2] << 16; 660 temp |= buf[1] << 8; 661 temp |= buf[0]; 662 buf += 8; 663 } 664 665 *((uint64_t *)LIBUSB20_ADD_BYTES(pd, 666 pd_offset)) = temp; 667 pd_offset += 8; 668 } 669 break; 670 671 case LIBUSB20_ME_STRUCT: 672 pd_offset = -((-pd_offset) & 673 ~(LIBUSB20_ME_STRUCT_ALIGN - 1)); /* align */ 674 while (pd_count--) { 675 uint16_t temp; 676 uint16_t dummy; 677 struct libusb20_me_struct *ps; 678 679 ps = LIBUSB20_ADD_BYTES(pd, pd_offset); 680 681 if (ps->type == LIBUSB20_ME_IS_ENCODED) { 682 /* 683 * Pre-store a de-constified 684 * pointer to the raw 685 * structure: 686 */ 687 ps->ptr = LIBUSB20_ADD_BYTES(buf, 0); 688 689 /* 690 * Get the correct number of 691 * length bytes: 692 */ 693 if (len != 0) { 694 if (buf[0] == 0xFF) { 695 ps->len = 3; 696 } else { 697 ps->len = 1; 698 } 699 } else { 700 ps->len = 0; 701 } 702 } 703 /* get the structure length */ 704 705 if (len != 0) { 706 if (buf[0] == 0xFF) { 707 if (len < 3) { 708 len = 0; 709 temp = 0; 710 } else { 711 len -= 3; 712 temp = buf[1] | 713 (buf[2] << 8); 714 buf += 3; 715 } 716 } else { 717 len -= 1; 718 temp = buf[0]; 719 buf += 1; 720 } 721 } else { 722 len = 0; 723 temp = 0; 724 } 725 /* check for invalid length */ 726 727 if (temp > len) { 728 len = 0; 729 temp = 0; 730 } 731 /* check wanted structure type */ 732 733 switch (ps->type) { 734 case LIBUSB20_ME_IS_ENCODED: 735 /* check for zero length */ 736 if (temp == 0) { 737 /* 738 * The pointer must 739 * be valid: 740 */ 741 ps->ptr = LIBUSB20_ADD_BYTES( 742 libusb20_me_encode_empty, 0); 743 ps->len = 1; 744 } else { 745 ps->len += temp; 746 } 747 break; 748 749 case LIBUSB20_ME_IS_RAW: 750 /* update length and pointer */ 751 ps->len = temp; 752 ps->ptr = LIBUSB20_ADD_BYTES(buf, 0); 753 break; 754 755 case LIBUSB20_ME_IS_EMPTY: 756 case LIBUSB20_ME_IS_DECODED: 757 /* check for non-zero length */ 758 if (temp != 0) { 759 /* update type */ 760 ps->type = LIBUSB20_ME_IS_DECODED; 761 ps->len = 0; 762 /* 763 * Recursivly decode 764 * the next structure 765 */ 766 dummy = libusb20_me_decode(buf, 767 temp, ps->ptr); 768 } else { 769 /* update type */ 770 ps->type = LIBUSB20_ME_IS_EMPTY; 771 ps->len = 0; 772 } 773 break; 774 775 default: 776 /* 777 * nothing to do - should 778 * not happen 779 */ 780 ps->ptr = NULL; 781 ps->len = 0; 782 break; 783 } 784 buf += temp; 785 len -= temp; 786 pd_offset += sizeof(struct libusb20_me_struct); 787 } 788 break; 789 790 default: 791 goto done; 792 } 793 } 794 done: 795 return (len_old - len); 796 } 797