lib/libusb/libusb20_desc.c

   1 /* $FreeBSD$ */
   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 initial config descriptor pointer!
 139          */
 140         memcpy((void *)(lub_endpoint + nendpoint), config_desc, pcdesc.len);
 141
 142         ptr = (const void *)(lub_endpoint + nendpoint);
 143         pcdesc.ptr = LIBUSB20_ADD_BYTES(ptr, 0);
 144
 145         /* init config structure */
 146
 147         LIBUSB20_INIT(LIBUSB20_CONFIG_DESC, &lub_config->desc);
 148
 149         if (libusb20_me_decode(ptr, ptr[0], &lub_config->desc)) {
 150                 /* ignore */
 151         }
 152         lub_config->num_interface = 0;
 153         lub_config->interface = lub_interface;
 154         lub_config->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]);
 155         lub_config->extra.len = -ptr[0];
 156         lub_config->extra.type = LIBUSB20_ME_IS_RAW;
 157
 158         /* reset states */
 159         niface = 0;
 160         iface_no = 0xFFFF;
 161         ptr = NULL;
 162         lub_interface--;
 163         lub_endpoint--;
 164         last_if = NULL;
 165         last_ep = NULL;
 166
 167         /* descriptor pre-scan */
 168         while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) {
 169                 if (ptr[1] == LIBUSB20_DT_ENDPOINT) {
 170                         if (last_if) {
 171                                 lub_endpoint++;
 172                                 last_ep = lub_endpoint;
 173                                 last_if->num_endpoints++;
 174
 175                                 LIBUSB20_INIT(LIBUSB20_ENDPOINT_DESC, &last_ep->desc);
 176
 177                                 if (libusb20_me_decode(ptr, ptr[0], &last_ep->desc)) {
 178                                         /* ignore */
 179                                 }
 180                                 last_ep->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]);
 181                                 last_ep->extra.len = 0;
 182                                 last_ep->extra.type = LIBUSB20_ME_IS_RAW;
 183                         } else {
 184                                 lub_config->extra.len += ptr[0];
 185                         }
 186
 187                 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) {
 188                         if (ptr[2] != iface_no) {
 189                                 /* new interface */
 190                                 iface_no = ptr[2];
 191                                 lub_interface++;
 192                                 lub_config->num_interface++;
 193                                 last_if = lub_interface;
 194                                 niface++;
 195                         } else {
 196                                 /* one more alternate setting */
 197                                 lub_interface->num_altsetting++;
 198                                 last_if = lub_alt_interface;
 199                                 lub_alt_interface++;
 200                         }
 201
 202                         LIBUSB20_INIT(LIBUSB20_INTERFACE_DESC, &last_if->desc);
 203
 204                         if (libusb20_me_decode(ptr, ptr[0], &last_if->desc)) {
 205                                 /* ignore */
 206                         }
 207                         /*
 208                          * Sometimes USB devices have corrupt interface
 209                          * descriptors and we need to overwrite the provided
 210                          * interface number!
 211                          */
 212                         last_if->desc.bInterfaceNumber = niface - 1;
 213                         last_if->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]);
 214                         last_if->extra.len = 0;
 215                         last_if->extra.type = LIBUSB20_ME_IS_RAW;
 216                         last_if->endpoints = lub_endpoint + 1;
 217                         last_if->altsetting = lub_alt_interface;
 218                         last_if->num_altsetting = 0;
 219                         last_if->num_endpoints = 0;
 220                         last_ep = NULL;
 221                 } else {
 222                         /* unknown descriptor */
 223                         if (last_if) {
 224                                 if (last_ep) {
 225                                         last_ep->extra.len += ptr[0];
 226                                 } else {
 227                                         last_if->extra.len += ptr[0];
 228                                 }
 229                         } else {
 230                                 lub_config->extra.len += ptr[0];
 231                         }
 232                 }
 233         }
 234         return (lub_config);
 235 }
 236
 237 /*------------------------------------------------------------------------*
 238  *      libusb20_desc_foreach
 239  *
 240  * Safe traversal of USB descriptors.
 241  *
 242  * Return values:
 243  * NULL: End of descriptors
 244  * Else: Pointer to next descriptor
 245  *------------------------------------------------------------------------*/
 246 const uint8_t *
 247 libusb20_desc_foreach(const struct libusb20_me_struct *pdesc,
 248     const uint8_t *psubdesc)
 249 {
 250         const uint8_t *start;
 251         const uint8_t *end;
 252         const uint8_t *desc_next;
 253
 254         /* be NULL safe */
 255         if (pdesc == NULL)
 256                 return (NULL);
 257
 258         start = (const uint8_t *)pdesc->ptr;
 259         end = LIBUSB20_ADD_BYTES(start, pdesc->len);
 260
 261         /* get start of next descriptor */
 262         if (psubdesc == NULL)
 263                 psubdesc = start;
 264         else
 265                 psubdesc = psubdesc + psubdesc[0];
 266
 267         /* check that the next USB descriptor is within the range */
 268         if ((psubdesc < start) || (psubdesc >= end))
 269                 return (NULL);          /* out of range, or EOD */
 270
 271         /* check start of the second next USB descriptor, if any */
 272         desc_next = psubdesc + psubdesc[0];
 273         if ((desc_next < start) || (desc_next > end))
 274                 return (NULL);          /* out of range */
 275
 276         /* check minimum descriptor length */
 277         if (psubdesc[0] < 3)
 278                 return (NULL);          /* too short descriptor */
 279
 280         return (psubdesc);              /* return start of next descriptor */
 281 }
 282
 283 /*------------------------------------------------------------------------*
 284  *      libusb20_me_get_1 - safety wrapper to read out one byte
 285  *------------------------------------------------------------------------*/
 286 uint8_t
 287 libusb20_me_get_1(const struct libusb20_me_struct *ie, uint16_t offset)
 288 {
 289         if (offset < ie->len) {
 290                 return (*((uint8_t *)LIBUSB20_ADD_BYTES(ie->ptr, offset)));
 291         }
 292         return (0);
 293 }
 294
 295 /*------------------------------------------------------------------------*
 296  *      libusb20_me_get_2 - safety wrapper to read out one word
 297  *------------------------------------------------------------------------*/
 298 uint16_t
 299 libusb20_me_get_2(const struct libusb20_me_struct *ie, uint16_t offset)
 300 {
 301         return (libusb20_me_get_1(ie, offset) |
 302             (libusb20_me_get_1(ie, offset + 1) << 8));
 303 }
 304
 305 /*------------------------------------------------------------------------*
 306  *      libusb20_me_encode - encode a message structure
 307  *
 308  * Description of parameters:
 309  * "len" - maximum length of output buffer
 310  * "ptr" - pointer to output buffer. If NULL, no data will be written
 311  * "pd" - source structure
 312  *
 313  * Return values:
 314  * 0..65535 - Number of bytes used, limited by the "len" input parameter.
 315  *------------------------------------------------------------------------*/
 316 uint16_t
 317 libusb20_me_encode(void *ptr, uint16_t len, const void *pd)
 318 {
 319         const uint8_t *pf;              /* pointer to format data */
 320         uint8_t *buf;                   /* pointer to output buffer */
 321
 322         uint32_t pd_offset;             /* decoded structure offset */
 323         uint16_t len_old;               /* old length */
 324         uint16_t pd_count;              /* decoded element count */
 325         uint8_t me;                     /* message element */
 326
 327         /* initialise */
 328
 329         len_old = len;
 330         buf = ptr;
 331         pd_offset = sizeof(void *);
 332         pf = (*((struct libusb20_me_format *const *)pd))->format;
 333
 334         /* scan */
 335
 336         while (1) {
 337
 338                 /* get information element */
 339
 340                 me = (pf[0]) & LIBUSB20_ME_MASK;
 341                 pd_count = pf[1] | (pf[2] << 8);
 342                 pf += 3;
 343
 344                 /* encode the message element */
 345
 346                 switch (me) {
 347                 case LIBUSB20_ME_INT8:
 348                         while (pd_count--) {
 349                                 uint8_t temp;
 350
 351                                 if (len < 1)    /* overflow */
 352                                         goto done;
 353                                 if (buf) {
 354                                         temp = *((const uint8_t *)
 355                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 356                                         buf[0] = temp;
 357                                         buf += 1;
 358                                 }
 359                                 pd_offset += 1;
 360                                 len -= 1;
 361                         }
 362                         break;
 363
 364                 case LIBUSB20_ME_INT16:
 365                         pd_offset = -((-pd_offset) & ~1);       /* align */
 366                         while (pd_count--) {
 367                                 uint16_t temp;
 368
 369                                 if (len < 2)    /* overflow */
 370                                         goto done;
 371
 372                                 if (buf) {
 373                                         temp = *((const uint16_t *)
 374                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 375                                         buf[1] = (temp >> 8) & 0xFF;
 376                                         buf[0] = temp & 0xFF;
 377                                         buf += 2;
 378                                 }
 379                                 pd_offset += 2;
 380                                 len -= 2;
 381                         }
 382                         break;
 383
 384                 case LIBUSB20_ME_INT32:
 385                         pd_offset = -((-pd_offset) & ~3);       /* align */
 386                         while (pd_count--) {
 387                                 uint32_t temp;
 388
 389                                 if (len < 4)    /* overflow */
 390                                         goto done;
 391                                 if (buf) {
 392                                         temp = *((const uint32_t *)
 393                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 394                                         buf[3] = (temp >> 24) & 0xFF;
 395                                         buf[2] = (temp >> 16) & 0xFF;
 396                                         buf[1] = (temp >> 8) & 0xFF;
 397                                         buf[0] = temp & 0xFF;
 398                                         buf += 4;
 399                                 }
 400                                 pd_offset += 4;
 401                                 len -= 4;
 402                         }
 403                         break;
 404
 405                 case LIBUSB20_ME_INT64:
 406                         pd_offset = -((-pd_offset) & ~7);       /* align */
 407                         while (pd_count--) {
 408                                 uint64_t temp;
 409
 410                                 if (len < 8)    /* overflow */
 411                                         goto done;
 412                                 if (buf) {
 413
 414                                         temp = *((const uint64_t *)
 415                                             LIBUSB20_ADD_BYTES(pd, pd_offset));
 416                                         buf[7] = (temp >> 56) & 0xFF;
 417                                         buf[6] = (temp >> 48) & 0xFF;
 418                                         buf[5] = (temp >> 40) & 0xFF;
 419                                         buf[4] = (temp >> 32) & 0xFF;
 420                                         buf[3] = (temp >> 24) & 0xFF;
 421                                         buf[2] = (temp >> 16) & 0xFF;
 422                                         buf[1] = (temp >> 8) & 0xFF;
 423                                         buf[0] = temp & 0xFF;
 424                                         buf += 8;
 425                                 }
 426                                 pd_offset += 8;
 427                                 len -= 8;
 428                         }
 429                         break;
 430
 431                 case LIBUSB20_ME_STRUCT:
 432                         pd_offset = -((-pd_offset) &
 433                             ~(LIBUSB20_ME_STRUCT_ALIGN - 1));   /* align */
 434                         while (pd_count--) {
 435                                 void *src_ptr;
 436                                 uint16_t src_len;
 437                                 struct libusb20_me_struct *ps;
 438
 439                                 ps = LIBUSB20_ADD_BYTES(pd, pd_offset);
 440
 441                                 switch (ps->type) {
 442                                 case LIBUSB20_ME_IS_RAW:
 443                                         src_len = ps->len;
 444                                         src_ptr = ps->ptr;
 445                                         break;
 446
 447                                 case LIBUSB20_ME_IS_ENCODED:
 448                                         if (ps->len == 0) {
 449                                                 /*
 450                                                  * Length is encoded
 451                                                  * in the data itself
 452                                                  * and should be
 453                                                  * correct:
 454                                                  */
 455                                                 ps->len = 0xFFFF;
 456                                         }
 457                                         src_len = libusb20_me_get_1(pd, 0);
 458                                         src_ptr = LIBUSB20_ADD_BYTES(ps->ptr, 1);
 459                                         if (src_len == 0xFF) {
 460                                                 /* length is escaped */
 461                                                 src_len = libusb20_me_get_2(pd, 1);
 462                                                 src_ptr =
 463                                                     LIBUSB20_ADD_BYTES(ps->ptr, 3);
 464                                         }
 465                                         break;
 466
 467                                 case LIBUSB20_ME_IS_DECODED:
 468                                         /* reserve 3 length bytes */
 469                                         src_len = libusb20_me_encode(NULL,
 470                                             0xFFFF - 3, ps->ptr);
 471                                         src_ptr = NULL;
 472                                         break;
 473
 474                                 default:        /* empty structure */
 475                                         src_len = 0;
 476                                         src_ptr = NULL;
 477                                         break;
 478                                 }
 479
 480                                 if (src_len > 0xFE) {
 481                                         if (src_len > (0xFFFF - 3))
 482                                                 /* overflow */
 483                                                 goto done;
 484
 485                                         if (len < (src_len + 3))
 486                                                 /* overflow */
 487                                                 goto done;
 488
 489                                         if (buf) {
 490                                                 buf[0] = 0xFF;
 491                                                 buf[1] = (src_len & 0xFF);
 492                                                 buf[2] = (src_len >> 8) & 0xFF;
 493                                                 buf += 3;
 494                                         }
 495                                         len -= (src_len + 3);
 496                                 } else {
 497                                         if (len < (src_len + 1))
 498                                                 /* overflow */
 499                                                 goto done;
 500
 501                                         if (buf) {
 502                                                 buf[0] = (src_len & 0xFF);
 503                                                 buf += 1;
 504                                         }
 505                                         len -= (src_len + 1);
 506                                 }
 507
 508                                 /* check for buffer and non-zero length */
 509
 510                                 if (buf && src_len) {
 511                                         if (ps->type == LIBUSB20_ME_IS_DECODED) {
 512                                                 /*
 513                                                  * Repeat encode
 514                                                  * procedure - we have
 515                                                  * room for the
 516                                                  * complete structure:
 517                                                  */
 518                                                 (void) libusb20_me_encode(buf,
 519                                                     0xFFFF - 3, ps->ptr);
 520                                         } else {
 521                                                 bcopy(src_ptr, buf, src_len);
 522                                         }
 523                                         buf += src_len;
 524                                 }
 525                                 pd_offset += sizeof(struct libusb20_me_struct);
 526                         }
 527                         break;
 528
 529                 default:
 530                         goto done;
 531                 }
 532         }
 533 done:
 534         return (len_old - len);
 535 }
 536
 537 /*------------------------------------------------------------------------*
 538  *      libusb20_me_decode - decode a message into a decoded structure
 539  *
 540  * Description of parameters:
 541  * "ptr" - message pointer
 542  * "len" - message length
 543  * "pd" - pointer to decoded structure
 544  *
 545  * Returns:
 546  * "0..65535" - number of bytes decoded, limited by "len"
 547  *------------------------------------------------------------------------*/
 548 uint16_t
 549 libusb20_me_decode(const void *ptr, uint16_t len, void *pd)
 550 {
 551         const uint8_t *pf;              /* pointer to format data */
 552         const uint8_t *buf;             /* pointer to input buffer */
 553
 554         uint32_t pd_offset;             /* decoded structure offset */
 555         uint16_t len_old;               /* old length */
 556         uint16_t pd_count;              /* decoded element count */
 557         uint8_t me;                     /* message element */
 558
 559         /* initialise */
 560
 561         len_old = len;
 562         buf = ptr;
 563         pd_offset = sizeof(void *);
 564         pf = (*((struct libusb20_me_format **)pd))->format;
 565
 566         /* scan */
 567
 568         while (1) {
 569
 570                 /* get information element */
 571
 572                 me = (pf[0]) & LIBUSB20_ME_MASK;
 573                 pd_count = pf[1] | (pf[2] << 8);
 574                 pf += 3;
 575
 576                 /* decode the message element by type */
 577
 578                 switch (me) {
 579                 case LIBUSB20_ME_INT8:
 580                         while (pd_count--) {
 581                                 uint8_t temp;
 582
 583                                 if (len < 1) {
 584                                         len = 0;
 585                                         temp = 0;
 586                                 } else {
 587                                         len -= 1;
 588                                         temp = buf[0];
 589                                         buf++;
 590                                 }
 591                                 *((uint8_t *)LIBUSB20_ADD_BYTES(pd,
 592                                     pd_offset)) = temp;
 593                                 pd_offset += 1;
 594                         }
 595                         break;
 596
 597                 case LIBUSB20_ME_INT16:
 598                         pd_offset = -((-pd_offset) & ~1);       /* align */
 599                         while (pd_count--) {
 600                                 uint16_t temp;
 601
 602                                 if (len < 2) {
 603                                         len = 0;
 604                                         temp = 0;
 605                                 } else {
 606                                         len -= 2;
 607                                         temp = buf[1] << 8;
 608                                         temp |= buf[0];
 609                                         buf += 2;
 610                                 }
 611                                 *((uint16_t *)LIBUSB20_ADD_BYTES(pd,
 612                                     pd_offset)) = temp;
 613                                 pd_offset += 2;
 614                         }
 615                         break;
 616
 617                 case LIBUSB20_ME_INT32:
 618                         pd_offset = -((-pd_offset) & ~3);       /* align */
 619                         while (pd_count--) {
 620                                 uint32_t temp;
 621
 622                                 if (len < 4) {
 623                                         len = 0;
 624                                         temp = 0;
 625                                 } else {
 626                                         len -= 4;
 627                                         temp = buf[3] << 24;
 628                                         temp |= buf[2] << 16;
 629                                         temp |= buf[1] << 8;
 630                                         temp |= buf[0];
 631                                         buf += 4;
 632                                 }
 633
 634                                 *((uint32_t *)LIBUSB20_ADD_BYTES(pd,
 635                                     pd_offset)) = temp;
 636                                 pd_offset += 4;
 637                         }
 638                         break;
 639
 640                 case LIBUSB20_ME_INT64:
 641                         pd_offset = -((-pd_offset) & ~7);       /* align */
 642                         while (pd_count--) {
 643                                 uint64_t temp;
 644
 645                                 if (len < 8) {
 646                                         len = 0;
 647                                         temp = 0;
 648                                 } else {
 649                                         len -= 8;
 650                                         temp = ((uint64_t)buf[7]) << 56;
 651                                         temp |= ((uint64_t)buf[6]) << 48;
 652                                         temp |= ((uint64_t)buf[5]) << 40;
 653                                         temp |= ((uint64_t)buf[4]) << 32;
 654                                         temp |= buf[3] << 24;
 655                                         temp |= buf[2] << 16;
 656                                         temp |= buf[1] << 8;
 657                                         temp |= buf[0];
 658                                         buf += 8;
 659                                 }
 660
 661                                 *((uint64_t *)LIBUSB20_ADD_BYTES(pd,
 662                                     pd_offset)) = temp;
 663                                 pd_offset += 8;
 664                         }
 665                         break;
 666
 667                 case LIBUSB20_ME_STRUCT:
 668                         pd_offset = -((-pd_offset) &
 669                             ~(LIBUSB20_ME_STRUCT_ALIGN - 1));   /* align */
 670                         while (pd_count--) {
 671                                 uint16_t temp;
 672                                 struct libusb20_me_struct *ps;
 673
 674                                 ps = LIBUSB20_ADD_BYTES(pd, pd_offset);
 675
 676                                 if (ps->type == LIBUSB20_ME_IS_ENCODED) {
 677                                         /*
 678                                          * Pre-store a de-constified
 679                                          * pointer to the raw
 680                                          * structure:
 681                                          */
 682                                         ps->ptr = LIBUSB20_ADD_BYTES(buf, 0);
 683
 684                                         /*
 685                                          * Get the correct number of
 686                                          * length bytes:
 687                                          */
 688                                         if (len != 0) {
 689                                                 if (buf[0] == 0xFF) {
 690                                                         ps->len = 3;
 691                                                 } else {
 692                                                         ps->len = 1;
 693                                                 }
 694                                         } else {
 695                                                 ps->len = 0;
 696                                         }
 697                                 }
 698                                 /* get the structure length */
 699
 700                                 if (len != 0) {
 701                                         if (buf[0] == 0xFF) {
 702                                                 if (len < 3) {
 703                                                         len = 0;
 704                                                         temp = 0;
 705                                                 } else {
 706                                                         len -= 3;
 707                                                         temp = buf[1] |
 708                                                             (buf[2] << 8);
 709                                                         buf += 3;
 710                                                 }
 711                                         } else {
 712                                                 len -= 1;
 713                                                 temp = buf[0];
 714                                                 buf += 1;
 715                                         }
 716                                 } else {
 717                                         len = 0;
 718                                         temp = 0;
 719                                 }
 720                                 /* check for invalid length */
 721
 722                                 if (temp > len) {
 723                                         len = 0;
 724                                         temp = 0;
 725                                 }
 726                                 /* check wanted structure type */
 727
 728                                 switch (ps->type) {
 729                                 case LIBUSB20_ME_IS_ENCODED:
 730                                         /* check for zero length */
 731                                         if (temp == 0) {
 732                                                 /*
 733                                                  * The pointer must
 734                                                  * be valid:
 735                                                  */
 736                                                 ps->ptr = LIBUSB20_ADD_BYTES(
 737                                                     libusb20_me_encode_empty, 0);
 738                                                 ps->len = 1;
 739                                         } else {
 740                                                 ps->len += temp;
 741                                         }
 742                                         break;
 743
 744                                 case LIBUSB20_ME_IS_RAW:
 745                                         /* update length and pointer */
 746                                         ps->len = temp;
 747                                         ps->ptr = LIBUSB20_ADD_BYTES(buf, 0);
 748                                         break;
 749
 750                                 case LIBUSB20_ME_IS_EMPTY:
 751                                 case LIBUSB20_ME_IS_DECODED:
 752                                         /* check for non-zero length */
 753                                         if (temp != 0) {
 754                                                 /* update type */
 755                                                 ps->type = LIBUSB20_ME_IS_DECODED;
 756                                                 ps->len = 0;
 757                                                 /*
 758                                                  * Recursivly decode
 759                                                  * the next structure
 760                                                  */
 761                                                 (void) libusb20_me_decode(buf,
 762                                                     temp, ps->ptr);
 763                                         } else {
 764                                                 /* update type */
 765                                                 ps->type = LIBUSB20_ME_IS_EMPTY;
 766                                                 ps->len = 0;
 767                                         }
 768                                         break;
 769
 770                                 default:
 771                                         /*
 772                                          * nothing to do - should
 773                                          * not happen
 774                                          */
 775                                         ps->ptr = NULL;
 776                                         ps->len = 0;
 777                                         break;
 778                                 }
 779                                 buf += temp;
 780                                 len -= temp;
 781                                 pd_offset += sizeof(struct libusb20_me_struct);
 782                         }
 783                         break;
 784
 785                 default:
 786                         goto done;
 787                 }
 788         }
 789 done:
 790         return (len_old - len);
 791 }