lib/libusb/libusb20_desc.c

   1 /* $FreeBSD$ */
   2 /*-
   3  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   4  *
   5  * Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #ifdef LIBUSB_GLOBAL_INCLUDE_FILE
  30 #include LIBUSB_GLOBAL_INCLUDE_FILE
  31 #else
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <time.h>
  36 #include <sys/queue.h>
  37 #endif
  38
  39 #include "libusb20.h"
  40 #include "libusb20_desc.h"
  41 #include "libusb20_int.h"
  42
  43 static const uint32_t libusb20_me_encode_empty[2];      /* dummy */
  44
  45 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_DEVICE_DESC);
  46 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_ENDPOINT_DESC);
  47 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_INTERFACE_DESC);
  48 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONFIG_DESC);
  49 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_CONTROL_SETUP);
  50 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_ENDPT_COMP_DESC);
  51 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_USB_20_DEVCAP_DESC);
  52 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_SS_USB_DEVCAP_DESC);
  53 LIBUSB20_MAKE_STRUCT_FORMAT(LIBUSB20_BOS_DESCRIPTOR);
  54
  55 /*------------------------------------------------------------------------*
  56  *      libusb20_parse_config_desc
  57  *
  58  * Return values:
  59  * NULL: Out of memory.
  60  * Else: A valid config structure pointer which must be passed to "free()"
  61  *------------------------------------------------------------------------*/
  62 struct libusb20_config *
  63 libusb20_parse_config_desc(const void *config_desc)
  64 {
  65         struct libusb20_config *lub_config;
  66         struct libusb20_interface *lub_interface;
  67         struct libusb20_interface *lub_alt_interface;
  68         struct libusb20_interface *last_if;
  69         struct libusb20_endpoint *lub_endpoint;
  70         struct libusb20_endpoint *last_ep;
  71
  72         struct libusb20_me_struct pcdesc;
  73         const uint8_t *ptr;
  74         uint32_t size;
  75         uint16_t niface_no_alt;
  76         uint16_t niface;
  77         uint16_t nendpoint;
  78         uint16_t iface_no;
  79
  80         ptr = config_desc;
  81         if (ptr[1] != LIBUSB20_DT_CONFIG) {
  82                 return (NULL);          /* not config descriptor */
  83         }
  84         /*
  85          * The first "bInterfaceNumber" should never have the value 0xff.
  86          * Then it is corrupt.
  87          */
  88         niface_no_alt = 0;
  89         nendpoint = 0;
  90         niface = 0;
  91         iface_no = 0xFFFF;
  92         ptr = NULL;
  93
  94         /* get "wTotalLength" and setup "pcdesc" */
  95         pcdesc.ptr = LIBUSB20_ADD_BYTES(config_desc, 0);
  96         pcdesc.len =
  97             ((const uint8_t *)config_desc)[2] |
  98             (((const uint8_t *)config_desc)[3] << 8);
  99         pcdesc.type = LIBUSB20_ME_IS_RAW;
 100
 101         /* descriptor pre-scan */
 102         while ((ptr = libusb20_desc_foreach(&pcdesc, ptr))) {
 103                 if (ptr[1] == LIBUSB20_DT_ENDPOINT) {
 104                         nendpoint++;
 105                 } else if ((ptr[1] == LIBUSB20_DT_INTERFACE) && (ptr[0] >= 4)) {
 106                         niface++;
 107                         /* check "bInterfaceNumber" */
 108                         if (ptr[2] != iface_no) {
 109                                 iface_no = ptr[2];
 110                                 niface_no_alt++;
 111                         }
 112                 }
 113         }
 114
 115         /* sanity checking */
 116         if (niface >= 256) {
 117                 return (NULL);          /* corrupt */
 118         }
 119         if (nendpoint >= 256) {
 120                 return (NULL);          /* corrupt */
 121         }
 122         size = sizeof(*lub_config) +
 123             (niface * sizeof(*lub_interface)) +
 124             (nendpoint * sizeof(*lub_endpoint)) +
 125             pcdesc.len;
 126
 127         lub_config = malloc(size);
 128         if (lub_config == NULL) {
 129                 return (NULL);          /* out of memory */
 130         }
 131         /* make sure memory is initialised */
 132         memset(lub_config, 0, size);
 133
 134         lub_interface = (void *)(lub_config + 1);
 135         lub_alt_interface = (void *)(lub_interface + niface_no_alt);
 136         lub_endpoint = (void *)(lub_interface + niface);
 137
 138         /*
 139          * Make a copy of the config descriptor, so that the caller can free
 140          * the initial config descriptor pointer!
 141          */
 142         memcpy((void *)(lub_endpoint + nendpoint), config_desc, pcdesc.len);
 143
 144         ptr = (const void *)(lub_endpoint + nendpoint);
 145         pcdesc.ptr = LIBUSB20_ADD_BYTES(ptr, 0);
 146
 147         /* init config structure */
 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                                                 (void) libusb20_me_encode(buf,
 521                                                     0xFFFF - 3, ps->ptr);
 522                                         } else {
 523                                                 bcopy(src_ptr, buf, src_len);
 524                                         }
 525                                         buf += src_len;
 526                                 }
 527                                 pd_offset += sizeof(struct libusb20_me_struct);
 528                         }
 529                         break;
 530
 531                 default:
 532                         goto done;
 533                 }
 534         }
 535 done:
 536         return (len_old - len);
 537 }
 538
 539 /*------------------------------------------------------------------------*
 540  *      libusb20_me_decode - decode a message into a decoded structure
 541  *
 542  * Description of parameters:
 543  * "ptr" - message pointer
 544  * "len" - message length
 545  * "pd" - pointer to decoded structure
 546  *
 547  * Returns:
 548  * "0..65535" - number of bytes decoded, limited by "len"
 549  *------------------------------------------------------------------------*/
 550 uint16_t
 551 libusb20_me_decode(const void *ptr, uint16_t len, void *pd)
 552 {
 553         const uint8_t *pf;              /* pointer to format data */
 554         const uint8_t *buf;             /* pointer to input buffer */
 555
 556         uint32_t pd_offset;             /* decoded structure offset */
 557         uint16_t len_old;               /* old length */
 558         uint16_t pd_count;              /* decoded element count */
 559         uint8_t me;                     /* message element */
 560
 561         /* initialise */
 562
 563         len_old = len;
 564         buf = ptr;
 565         pd_offset = sizeof(void *);
 566         pf = (*((struct libusb20_me_format **)pd))->format;
 567
 568         /* scan */
 569
 570         while (1) {
 571
 572                 /* get information element */
 573
 574                 me = (pf[0]) & LIBUSB20_ME_MASK;
 575                 pd_count = pf[1] | (pf[2] << 8);
 576                 pf += 3;
 577
 578                 /* decode the message element by type */
 579
 580                 switch (me) {
 581                 case LIBUSB20_ME_INT8:
 582                         while (pd_count--) {
 583                                 uint8_t temp;
 584
 585                                 if (len < 1) {
 586                                         len = 0;
 587                                         temp = 0;
 588                                 } else {
 589                                         len -= 1;
 590                                         temp = buf[0];
 591                                         buf++;
 592                                 }
 593                                 *((uint8_t *)LIBUSB20_ADD_BYTES(pd,
 594                                     pd_offset)) = temp;
 595                                 pd_offset += 1;
 596                         }
 597                         break;
 598
 599                 case LIBUSB20_ME_INT16:
 600                         pd_offset = -((-pd_offset) & ~1);       /* align */
 601                         while (pd_count--) {
 602                                 uint16_t temp;
 603
 604                                 if (len < 2) {
 605                                         len = 0;
 606                                         temp = 0;
 607                                 } else {
 608                                         len -= 2;
 609                                         temp = buf[1] << 8;
 610                                         temp |= buf[0];
 611                                         buf += 2;
 612                                 }
 613                                 *((uint16_t *)LIBUSB20_ADD_BYTES(pd,
 614                                     pd_offset)) = temp;
 615                                 pd_offset += 2;
 616                         }
 617                         break;
 618
 619                 case LIBUSB20_ME_INT32:
 620                         pd_offset = -((-pd_offset) & ~3);       /* align */
 621                         while (pd_count--) {
 622                                 uint32_t temp;
 623
 624                                 if (len < 4) {
 625                                         len = 0;
 626                                         temp = 0;
 627                                 } else {
 628                                         len -= 4;
 629                                         temp = buf[3] << 24;
 630                                         temp |= buf[2] << 16;
 631                                         temp |= buf[1] << 8;
 632                                         temp |= buf[0];
 633                                         buf += 4;
 634                                 }
 635
 636                                 *((uint32_t *)LIBUSB20_ADD_BYTES(pd,
 637                                     pd_offset)) = temp;
 638                                 pd_offset += 4;
 639                         }
 640                         break;
 641
 642                 case LIBUSB20_ME_INT64:
 643                         pd_offset = -((-pd_offset) & ~7);       /* align */
 644                         while (pd_count--) {
 645                                 uint64_t temp;
 646
 647                                 if (len < 8) {
 648                                         len = 0;
 649                                         temp = 0;
 650                                 } else {
 651                                         len -= 8;
 652                                         temp = ((uint64_t)buf[7]) << 56;
 653                                         temp |= ((uint64_t)buf[6]) << 48;
 654                                         temp |= ((uint64_t)buf[5]) << 40;
 655                                         temp |= ((uint64_t)buf[4]) << 32;
 656                                         temp |= buf[3] << 24;
 657                                         temp |= buf[2] << 16;
 658                                         temp |= buf[1] << 8;
 659                                         temp |= buf[0];
 660                                         buf += 8;
 661                                 }
 662
 663                                 *((uint64_t *)LIBUSB20_ADD_BYTES(pd,
 664                                     pd_offset)) = temp;
 665                                 pd_offset += 8;
 666                         }
 667                         break;
 668
 669                 case LIBUSB20_ME_STRUCT:
 670                         pd_offset = -((-pd_offset) &
 671                             ~(LIBUSB20_ME_STRUCT_ALIGN - 1));   /* align */
 672                         while (pd_count--) {
 673                                 uint16_t temp;
 674                                 struct libusb20_me_struct *ps;
 675
 676                                 ps = LIBUSB20_ADD_BYTES(pd, pd_offset);
 677
 678                                 if (ps->type == LIBUSB20_ME_IS_ENCODED) {
 679                                         /*
 680                                          * Pre-store a de-constified
 681                                          * pointer to the raw
 682                                          * structure:
 683                                          */
 684                                         ps->ptr = LIBUSB20_ADD_BYTES(buf, 0);
 685
 686                                         /*
 687                                          * Get the correct number of
 688                                          * length bytes:
 689                                          */
 690                                         if (len != 0) {
 691                                                 if (buf[0] == 0xFF) {
 692                                                         ps->len = 3;
 693                                                 } else {
 694                                                         ps->len = 1;
 695                                                 }
 696                                         } else {
 697                                                 ps->len = 0;
 698                                         }
 699                                 }
 700                                 /* get the structure length */
 701
 702                                 if (len != 0) {
 703                                         if (buf[0] == 0xFF) {
 704                                                 if (len < 3) {
 705                                                         len = 0;
 706                                                         temp = 0;
 707                                                 } else {
 708                                                         len -= 3;
 709                                                         temp = buf[1] |
 710                                                             (buf[2] << 8);
 711                                                         buf += 3;
 712                                                 }
 713                                         } else {
 714                                                 len -= 1;
 715                                                 temp = buf[0];
 716                                                 buf += 1;
 717                                         }
 718                                 } else {
 719                                         len = 0;
 720                                         temp = 0;
 721                                 }
 722                                 /* check for invalid length */
 723
 724                                 if (temp > len) {
 725                                         len = 0;
 726                                         temp = 0;
 727                                 }
 728                                 /* check wanted structure type */
 729
 730                                 switch (ps->type) {
 731                                 case LIBUSB20_ME_IS_ENCODED:
 732                                         /* check for zero length */
 733                                         if (temp == 0) {
 734                                                 /*
 735                                                  * The pointer must
 736                                                  * be valid:
 737                                                  */
 738                                                 ps->ptr = LIBUSB20_ADD_BYTES(
 739                                                     libusb20_me_encode_empty, 0);
 740                                                 ps->len = 1;
 741                                         } else {
 742                                                 ps->len += temp;
 743                                         }
 744                                         break;
 745
 746                                 case LIBUSB20_ME_IS_RAW:
 747                                         /* update length and pointer */
 748                                         ps->len = temp;
 749                                         ps->ptr = LIBUSB20_ADD_BYTES(buf, 0);
 750                                         break;
 751
 752                                 case LIBUSB20_ME_IS_EMPTY:
 753                                 case LIBUSB20_ME_IS_DECODED:
 754                                         /* check for non-zero length */
 755                                         if (temp != 0) {
 756                                                 /* update type */
 757                                                 ps->type = LIBUSB20_ME_IS_DECODED;
 758                                                 ps->len = 0;
 759                                                 /*
 760                                                  * Recursivly decode
 761                                                  * the next structure
 762                                                  */
 763                                                 (void) libusb20_me_decode(buf,
 764                                                     temp, ps->ptr);
 765                                         } else {
 766                                                 /* update type */
 767                                                 ps->type = LIBUSB20_ME_IS_EMPTY;
 768                                                 ps->len = 0;
 769                                         }
 770                                         break;
 771
 772                                 default:
 773                                         /*
 774                                          * nothing to do - should
 775                                          * not happen
 776                                          */
 777                                         ps->ptr = NULL;
 778                                         ps->len = 0;
 779                                         break;
 780                                 }
 781                                 buf += temp;
 782                                 len -= temp;
 783                                 pd_offset += sizeof(struct libusb20_me_struct);
 784                         }
 785                         break;
 786
 787                 default:
 788                         goto done;
 789                 }
 790         }
 791 done:
 792         return (len_old - len);
 793 }