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