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/param.h> 35 #include <sys/queue.h> 36 #endif 37 38 #include "libusb20.h" 39 #include "libusb20_desc.h" 40 #include "libusb20_int.h" 41 42 static const uint32_t libusb20_me_encode_empty[2]; /* dummy */ 43 44 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_DEVICE_DESC); 45 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_ENDPOINT_DESC); 46 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_INTERFACE_DESC); 47 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONFIG_DESC); 48 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONTROL_SETUP); 49 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_ENDPT_COMP_DESC); 50 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_USB_20_DEVCAP_DESC); 51 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_USB_DEVCAP_DESC); 52 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_BOS_DESCRIPTOR); 53 54 /*------------------------------------------------------------------------* 55 * libusb20_parse_config_desc 56 * 57 * Return values: 58 * NULL: Out of memory. 59 * Else: A valid config structure pointer which must be passed to "free()" 60 *------------------------------------------------------------------------*/ 61 struct libusb20_config * 62 libusb20_parse_config_desc(const void *config_desc) 63 { 64 struct libusb20_config *lub_config; 65 struct libusb20_interface *lub_interface; 66 struct libusb20_interface *lub_alt_interface; 67 struct libusb20_interface *last_if; 68 struct libusb20_endpoint *lub_endpoint; 69 struct libusb20_endpoint *last_ep; 70 71 struct libusb20_me_struct pcdesc; 72 const uint8_t *ptr; 73 uint32_t size; 74 uint16_t niface_no_alt; 75 uint16_t niface; 76 uint16_t nendpoint; 77 uint16_t iface_no; 78 79 ptr = config_desc; 80 if (ptr[1] != LIBUSB20_DT_CONFIG) { 81 return (NULL); /* not config descriptor */ 82 } 83 /* 84 * The first "bInterfaceNumber" should never have the value 0xff. 85 * Then it is corrupt. 86 */ 87 niface_no_alt = 0; 88 nendpoint = 0; 89 niface = 0; 90 iface_no = 0xFFFF; 91 ptr = NULL; 92 93 /* get "wTotalLength" and setup "pcdesc" */ 94 pcdesc.ptr = LIBUSB20_ADD_BYTES(config_desc, 0); 95 pcdesc.len = 96 ((const uint8_t *)config_desc)[2] | 97 (((const uint8_t *)config_desc)[3] << 8); 98 pcdesc.type = LIBUSB20_ME_IS_RAW; 99 100 /* descriptor pre-scan */ 101 while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) { 102 if (ptr[1] == LIBUSB20_DT_ENDPOINT) { 103 nendpoint++; 104 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) { 105 niface++; 106 /* check "bInterfaceNumber" */ 107 if (ptr[2] != iface_no) { 108 iface_no = ptr[2]; 109 niface_no_alt++; 110 } 111 } 112 } 113 114 /* sanity checking */ 115 if (niface >= 256) { 116 return (NULL); /* corrupt */ 117 } 118 if (nendpoint >= 256) { 119 return (NULL); /* corrupt */ 120 } 121 size = sizeof(*lub_config) + 122 (niface * sizeof(*lub_interface)) + 123 (nendpoint * sizeof(*lub_endpoint)) + 124 pcdesc.len; 125 126 lub_config = malloc(size); 127 if (lub_config == NULL) { 128 return (NULL); /* out of memory */ 129 } 130 /* make sure memory is initialised */ 131 memset(lub_config, 0, size); 132 133 lub_interface = (void *)(lub_config + 1); 134 lub_alt_interface = (void *)(lub_interface + niface_no_alt); 135 lub_endpoint = (void *)(lub_interface + niface); 136 137 /* 138 * Make a copy of the config descriptor, so that the caller can free 139 * the inital config descriptor pointer! 140 */ 141 ptr = (void *)(lub_endpoint + nendpoint); 142 memcpy(LIBUSB20_ADD_BYTES(ptr, 0), config_desc, pcdesc.len); 143 pcdesc.ptr = LIBUSB20_ADD_BYTES(ptr, 0); 144 config_desc = LIBUSB20_ADD_BYTES(ptr, 0); 145 146 /* init config structure */ 147 148 ptr = config_desc; 149 150 LIBUSB20_INIT(LIBUSB20_CONFIG_DESC, &lub_config->desc); 151 152 if (libusb20_me_decode(ptr, ptr[0], &lub_config->desc)) { 153 /* ignore */ 154 } 155 lub_config->num_interface = 0; 156 lub_config->interface = lub_interface; 157 lub_config->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); 158 lub_config->extra.len = -ptr[0]; 159 lub_config->extra.type = LIBUSB20_ME_IS_RAW; 160 161 /* reset states */ 162 niface = 0; 163 iface_no = 0xFFFF; 164 ptr = NULL; 165 lub_interface--; 166 lub_endpoint--; 167 last_if = NULL; 168 last_ep = NULL; 169 170 /* descriptor pre-scan */ 171 while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) { 172 if (ptr[1] == LIBUSB20_DT_ENDPOINT) { 173 if (last_if) { 174 lub_endpoint++; 175 last_ep = lub_endpoint; 176 last_if->num_endpoints++; 177 178 LIBUSB20_INIT(LIBUSB20_ENDPOINT_DESC, &last_ep->desc); 179 180 if (libusb20_me_decode(ptr, ptr[0], &last_ep->desc)) { 181 /* ignore */ 182 } 183 last_ep->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); 184 last_ep->extra.len = 0; 185 last_ep->extra.type = LIBUSB20_ME_IS_RAW; 186 } else { 187 lub_config->extra.len += ptr[0]; 188 } 189 190 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) { 191 if (ptr[2] != iface_no) { 192 /* new interface */ 193 iface_no = ptr[2]; 194 lub_interface++; 195 lub_config->num_interface++; 196 last_if = lub_interface; 197 niface++; 198 } else { 199 /* one more alternate setting */ 200 lub_interface->num_altsetting++; 201 last_if = lub_alt_interface; 202 lub_alt_interface++; 203 } 204 205 LIBUSB20_INIT(LIBUSB20_INTERFACE_DESC, &last_if->desc); 206 207 if (libusb20_me_decode(ptr, ptr[0], &last_if->desc)) { 208 /* ignore */ 209 } 210 /* 211 * Sometimes USB devices have corrupt interface 212 * descriptors and we need to overwrite the provided 213 * interface number! 214 */ 215 last_if->desc.bInterfaceNumber = niface - 1; 216 last_if->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); 217 last_if->extra.len = 0; 218 last_if->extra.type = LIBUSB20_ME_IS_RAW; 219 last_if->endpoints = lub_endpoint + 1; 220 last_if->altsetting = lub_alt_interface; 221 last_if->num_altsetting = 0; 222 last_if->num_endpoints = 0; 223 last_ep = NULL; 224 } else { 225 /* unknown descriptor */ 226 if (last_if) { 227 if (last_ep) { 228 last_ep->extra.len += ptr[0]; 229 } else { 230 last_if->extra.len += ptr[0]; 231 } 232 } else { 233 lub_config->extra.len += ptr[0]; 234 } 235 } 236 } 237 return (lub_config); 238 } 239 240 /*------------------------------------------------------------------------* 241 * libusb20_desc_foreach 242 * 243 * Safe traversal of USB descriptors. 244 * 245 * Return values: 246 * NULL: End of descriptors 247 * Else: Pointer to next descriptor 248 *------------------------------------------------------------------------*/ 249 const uint8_t * 250 libusb20_desc_foreach(const struct libusb20_me_struct *pdesc, 251 const uint8_t *psubdesc) 252 { 253 const uint8_t *start; 254 const uint8_t *end; 255 const uint8_t *desc_next; 256 257 /* be NULL safe */ 258 if (pdesc == NULL) 259 return (NULL); 260 261 start = (const uint8_t *)pdesc->ptr; 262 end = LIBUSB20_ADD_BYTES(start, pdesc->len); 263 264 /* get start of next descriptor */ 265 if (psubdesc == NULL) 266 psubdesc = start; 267 else 268 psubdesc = psubdesc + psubdesc[0]; 269 270 /* check that the next USB descriptor is within the range */ 271 if ((psubdesc < start) || (psubdesc >= end)) 272 return (NULL); /* out of range, or EOD */ 273 274 /* check start of the second next USB descriptor, if any */ 275 desc_next = psubdesc + psubdesc[0]; 276 if ((desc_next < start) || (desc_next > end)) 277 return (NULL); /* out of range */ 278 279 /* check minimum descriptor length */ 280 if (psubdesc[0] < 3) 281 return (NULL); /* too short descriptor */ 282 283 return (psubdesc); /* return start of next descriptor */ 284 } 285 286 /*------------------------------------------------------------------------* 287 * libusb20_me_get_1 - safety wrapper to read out one byte 288 *------------------------------------------------------------------------*/ 289 uint8_t 290 libusb20_me_get_1(const struct libusb20_me_struct *ie, uint16_t offset) 291 { 292 if (offset < ie->len) { 293 return (*((uint8_t *)LIBUSB20_ADD_BYTES(ie->ptr, offset))); 294 } 295 return (0); 296 } 297 298 /*------------------------------------------------------------------------* 299 * libusb20_me_get_2 - safety wrapper to read out one word 300 *------------------------------------------------------------------------*/ 301 uint16_t 302 libusb20_me_get_2(const struct libusb20_me_struct *ie, uint16_t offset) 303 { 304 return (libusb20_me_get_1(ie, offset) | 305 (libusb20_me_get_1(ie, offset + 1) << 8)); 306 } 307 308 /*------------------------------------------------------------------------* 309 * libusb20_me_encode - encode a message structure 310 * 311 * Description of parameters: 312 * "len" - maximum length of output buffer 313 * "ptr" - pointer to output buffer. If NULL, no data will be written 314 * "pd" - source structure 315 * 316 * Return values: 317 * 0..65535 - Number of bytes used, limited by the "len" input parameter. 318 *------------------------------------------------------------------------*/ 319 uint16_t 320 libusb20_me_encode(void *ptr, uint16_t len, const void *pd) 321 { 322 const uint8_t *pf; /* pointer to format data */ 323 uint8_t *buf; /* pointer to output buffer */ 324 325 uint32_t pd_offset; /* decoded structure offset */ 326 uint16_t len_old; /* old length */ 327 uint16_t pd_count; /* decoded element count */ 328 uint8_t me; /* message element */ 329 330 /* initialise */ 331 332 len_old = len; 333 buf = ptr; 334 pd_offset = sizeof(void *); 335 pf = (*((struct libusb20_me_format *const *)pd))->format; 336 337 /* scan */ 338 339 while (1) { 340 341 /* get information element */ 342 343 me = (pf[0]) & LIBUSB20_ME_MASK; 344 pd_count = pf[1] | (pf[2] << 8); 345 pf += 3; 346 347 /* encode the message element */ 348 349 switch (me) { 350 case LIBUSB20_ME_INT8: 351 while (pd_count--) { 352 uint8_t temp; 353 354 if (len < 1) /* overflow */ 355 goto done; 356 if (buf) { 357 temp = *((const uint8_t *) 358 LIBUSB20_ADD_BYTES(pd, pd_offset)); 359 buf[0] = temp; 360 buf += 1; 361 } 362 pd_offset += 1; 363 len -= 1; 364 } 365 break; 366 367 case LIBUSB20_ME_INT16: 368 pd_offset = -((-pd_offset) & ~1); /* align */ 369 while (pd_count--) { 370 uint16_t temp; 371 372 if (len < 2) /* overflow */ 373 goto done; 374 375 if (buf) { 376 temp = *((const uint16_t *) 377 LIBUSB20_ADD_BYTES(pd, pd_offset)); 378 buf[1] = (temp >> 8) & 0xFF; 379 buf[0] = temp & 0xFF; 380 buf += 2; 381 } 382 pd_offset += 2; 383 len -= 2; 384 } 385 break; 386 387 case LIBUSB20_ME_INT32: 388 pd_offset = -((-pd_offset) & ~3); /* align */ 389 while (pd_count--) { 390 uint32_t temp; 391 392 if (len < 4) /* overflow */ 393 goto done; 394 if (buf) { 395 temp = *((const uint32_t *) 396 LIBUSB20_ADD_BYTES(pd, pd_offset)); 397 buf[3] = (temp >> 24) & 0xFF; 398 buf[2] = (temp >> 16) & 0xFF; 399 buf[1] = (temp >> 8) & 0xFF; 400 buf[0] = temp & 0xFF; 401 buf += 4; 402 } 403 pd_offset += 4; 404 len -= 4; 405 } 406 break; 407 408 case LIBUSB20_ME_INT64: 409 pd_offset = -((-pd_offset) & ~7); /* align */ 410 while (pd_count--) { 411 uint64_t temp; 412 413 if (len < 8) /* overflow */ 414 goto done; 415 if (buf) { 416 417 temp = *((const uint64_t *) 418 LIBUSB20_ADD_BYTES(pd, pd_offset)); 419 buf[7] = (temp >> 56) & 0xFF; 420 buf[6] = (temp >> 48) & 0xFF; 421 buf[5] = (temp >> 40) & 0xFF; 422 buf[4] = (temp >> 32) & 0xFF; 423 buf[3] = (temp >> 24) & 0xFF; 424 buf[2] = (temp >> 16) & 0xFF; 425 buf[1] = (temp >> 8) & 0xFF; 426 buf[0] = temp & 0xFF; 427 buf += 8; 428 } 429 pd_offset += 8; 430 len -= 8; 431 } 432 break; 433 434 case LIBUSB20_ME_STRUCT: 435 pd_offset = -rounddown2(-pd_offset, LIBUSB20_ME_STRUCT_ALIGN); /* 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 = -rounddown2(-pd_offset, LIBUSB20_ME_STRUCT_ALIGN); /* align */ 673 while (pd_count--) { 674 uint16_t temp; 675 uint16_t dummy; 676 struct libusb20_me_struct *ps; 677 678 ps = LIBUSB20_ADD_BYTES(pd, pd_offset); 679 680 if (ps->type == LIBUSB20_ME_IS_ENCODED) { 681 /* 682 * Pre-store a de-constified 683 * pointer to the raw 684 * structure: 685 */ 686 ps->ptr = LIBUSB20_ADD_BYTES(buf, 0); 687 688 /* 689 * Get the correct number of 690 * length bytes: 691 */ 692 if (len != 0) { 693 if (buf[0] == 0xFF) { 694 ps->len = 3; 695 } else { 696 ps->len = 1; 697 } 698 } else { 699 ps->len = 0; 700 } 701 } 702 /* get the structure length */ 703 704 if (len != 0) { 705 if (buf[0] == 0xFF) { 706 if (len < 3) { 707 len = 0; 708 temp = 0; 709 } else { 710 len -= 3; 711 temp = buf[1] | 712 (buf[2] << 8); 713 buf += 3; 714 } 715 } else { 716 len -= 1; 717 temp = buf[0]; 718 buf += 1; 719 } 720 } else { 721 len = 0; 722 temp = 0; 723 } 724 /* check for invalid length */ 725 726 if (temp > len) { 727 len = 0; 728 temp = 0; 729 } 730 /* check wanted structure type */ 731 732 switch (ps->type) { 733 case LIBUSB20_ME_IS_ENCODED: 734 /* check for zero length */ 735 if (temp == 0) { 736 /* 737 * The pointer must 738 * be valid: 739 */ 740 ps->ptr = LIBUSB20_ADD_BYTES( 741 libusb20_me_encode_empty, 0); 742 ps->len = 1; 743 } else { 744 ps->len += temp; 745 } 746 break; 747 748 case LIBUSB20_ME_IS_RAW: 749 /* update length and pointer */ 750 ps->len = temp; 751 ps->ptr = LIBUSB20_ADD_BYTES(buf, 0); 752 break; 753 754 case LIBUSB20_ME_IS_EMPTY: 755 case LIBUSB20_ME_IS_DECODED: 756 /* check for non-zero length */ 757 if (temp != 0) { 758 /* update type */ 759 ps->type = LIBUSB20_ME_IS_DECODED; 760 ps->len = 0; 761 /* 762 * Recursivly decode 763 * the next structure 764 */ 765 dummy = libusb20_me_decode(buf, 766 temp, ps->ptr); 767 } else { 768 /* update type */ 769 ps->type = LIBUSB20_ME_IS_EMPTY; 770 ps->len = 0; 771 } 772 break; 773 774 default: 775 /* 776 * nothing to do - should 777 * not happen 778 */ 779 ps->ptr = NULL; 780 ps->len = 0; 781 break; 782 } 783 buf += temp; 784 len -= temp; 785 pd_offset += sizeof(struct libusb20_me_struct); 786 } 787 break; 788 789 default: 790 goto done; 791 } 792 } 793 done: 794 return (len_old - len); 795 } 796