libdvdcss.c 23.9 KB
Newer Older
1
/* libdvdcss.c: DVD reading library.
Sam Hocevar's avatar
 
Sam Hocevar committed
2
 *
3
 * Authors: Stéphane Borel <stef@via.ecp.fr>
4
 *          Sam Hocevar <sam@zoy.org>
5
 *          Håkan Hjort <d95hjort@dtek.chalmers.se>
Sam Hocevar's avatar
 
Sam Hocevar committed
6
 *
7
 * Copyright (C) 1998-2008 VideoLAN
8
 *
9
 * libdvdcss is free software; you can redistribute it and/or modify
Sam Hocevar's avatar
 
Sam Hocevar committed
10 11 12
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
13
 *
14
 * libdvdcss is distributed in the hope that it will be useful,
Sam Hocevar's avatar
 
Sam Hocevar committed
15 16 17 18
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
Diego Biurrun's avatar
Diego Biurrun committed
19
 * You should have received a copy of the GNU General Public License along
20
 * with libdvdcss; if not, write to the Free Software Foundation, Inc.,
Diego Biurrun's avatar
Diego Biurrun committed
21
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 23
 */

24
/**
25 26 27 28 29 30 31
 * \mainpage libdvdcss developer documentation
 *
 * \section intro Introduction
 *
 * \e libdvdcss is a simple library designed for accessing DVDs like a block
 * device without having to bother about the decryption. The important features
 * are:
32
 * \li portability: Currently supported platforms are GNU/Linux, FreeBSD,
33
 *     NetBSD, OpenBSD, Haiku, Mac OS X, Solaris, QNX, OS/2, and Windows
34
 *     NT 4.0 SP4 (with IE 5.0) or later.
35
 * \li adaptability: Unlike most similar projects, libdvdcss does not require
36 37
 *     the region of your drive to be set and will try its best to read from
 *     the disc even in the case of a region mismatch.
38
 * \li simplicity: A DVD player can be built around the \e libdvdcss API using
39 40
 *     no more than 4 or 5 library calls.
 *
41
 * \e libdvdcss is free software, released under the GNU General Public License.
42 43 44 45 46 47 48 49 50 51
 * This ensures that \e libdvdcss remains free and used only with free
 * software.
 *
 * \section api The libdvdcss API
 *
 * The complete \e libdvdcss programming interface is documented in the
 * dvdcss.h file.
 *
 * \section env Environment variables
 *
52
 * Some environment variables can be used to change the behavior of
53 54 55
 * \e libdvdcss without having to modify the program which uses it. These
 * variables are:
 *
56
 * \li \b DVDCSS_VERBOSE: Sets the verbosity level.
57 58 59 60
 *     - \c 0 outputs no messages at all.
 *     - \c 1 outputs error messages to stderr.
 *     - \c 2 outputs error messages and debug messages to stderr.
 *
61
 * \li \b DVDCSS_METHOD: Sets the authentication and decryption method
62 63 64 65 66 67 68 69 70 71 72
 *     that \e libdvdcss will use to read scrambled discs. Can be one
 *     of \c title, \c key or \c disc.
 *     - \c key is the default method. \e libdvdcss will use a set of
 *       calculated player keys to try and get the disc key. This can fail
 *       if the drive does not recognize any of the player keys.
 *     - \c disc is a fallback method when \c key has failed. Instead of
 *       using player keys, \e libdvdcss will crack the disc key using
 *       a brute force algorithm. This process is CPU intensive and requires
 *       64 MB of memory to store temporary data.
 *     - \c title is the fallback when all other methods have failed. It does
 *       not rely on a key exchange with the DVD drive, but rather uses a
73
 *       crypto attack to guess the title key. In rare cases this may fail
74
 *       because there is not enough encrypted data on the disc to perform
75
 *       a statistical attack, but on the other hand it is the only way to
76 77 78
 *       decrypt a DVD stored on a hard disc, or a DVD with the wrong region
 *       on an RPC2 drive.
 *
79
 * \li \b DVDCSS_RAW_DEVICE: Specify the raw device to use. Exact usage will
80 81 82 83
 *     depend on your operating system, the Linux utility to set up raw devices
 *     is \c raw(8) for instance. Please note that on most operating systems,
 *     using a raw device requires highly aligned buffers: Linux requires a
 *     2048 bytes alignment (which is the size of a DVD sector).
84
 *
85
 * \li \b DVDCSS_CACHE: Specify a directory in which to cache title key
86 87 88
 *     values. This will speed up descrambling of DVDs which are in the
 *     cache. The DVDCSS_CACHE directory is created if it does not exist,
 *     and a subdirectory is created named after the DVD's title or
89 90 91 92
 *     manufacturing date. If DVDCSS_CACHE is not set or is empty, \e libdvdcss
 *     will use the default value which is "${HOME}/.dvdcss/" under Unix and
 *     "C:\Documents and Settings\$USER\Application Data\dvdcss\" under Win32.
 *     The special value "off" disables caching.
93
 */
Sam Hocevar's avatar
 
Sam Hocevar committed
94

95
/*
Sam Hocevar's avatar
 
Sam Hocevar committed
96
 * Preamble
97
 */
Sam Hocevar's avatar
 
Sam Hocevar committed
98 99
#include "config.h"

Diego Biurrun's avatar
Diego Biurrun committed
100
#include <limits.h>
Sam Hocevar's avatar
 
Sam Hocevar committed
101 102 103 104 105
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
106 107 108
#ifdef HAVE_SYS_PARAM_H
#   include <sys/param.h>
#endif
109 110 111
#ifdef HAVE_PWD_H
#   include <pwd.h>
#endif
Sam Hocevar's avatar
 
Sam Hocevar committed
112
#include <fcntl.h>
113
#include <errno.h>
Sam Hocevar's avatar
 
Sam Hocevar committed
114 115 116 117 118

#ifdef HAVE_UNISTD_H
#   include <unistd.h>
#endif

119 120 121 122
#if defined(_WIN32_IE) && _WIN32_IE >= 0x500
#   include <shlobj.h>
#endif

Sam Hocevar's avatar
 
Sam Hocevar committed
123
#include "dvdcss/dvdcss.h"
Sam Hocevar's avatar
 
Sam Hocevar committed
124 125 126 127 128

#include "common.h"
#include "css.h"
#include "libdvdcss.h"
#include "ioctl.h"
129
#include "device.h"
Sam Hocevar's avatar
 
Sam Hocevar committed
130

131
#ifdef HAVE_BROKEN_MKDIR
132
#include <direct.h>
133 134 135
#define mkdir(a, b) _mkdir(a)
#endif

136
#define CACHE_TAG_NAME "CACHEDIR.TAG"
137

138
#define STRING_KEY_SIZE (DVD_KEY_SIZE * 2)
139 140 141 142 143 144 145
#define INTERESTING_SECTOR 16
#define DISC_TITLE_OFFSET  40
#define DISC_TITLE_LENGTH  32
#define MANUFACTURING_DATE_OFFSET 813
#define MANUFACTURING_DATE_LENGTH  16


146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163
static void set_verbosity( dvdcss_t dvdcss )
{
    const char *psz_verbose = getenv( "DVDCSS_VERBOSE" );

    dvdcss->b_debug  = 0;
    dvdcss->b_errors = 0;

    if( psz_verbose != NULL )
    {
        int i = atoi( psz_verbose );

        if( i >= 2 )
            dvdcss->b_debug  = 1;
        if( i >= 1 )
            dvdcss->b_errors = 1;
    }
}

164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191
static int set_access_method( dvdcss_t dvdcss )
{
    const char *psz_method = getenv( "DVDCSS_METHOD" );

    if( !psz_method )
        return 0;

    if( !strncmp( psz_method, "key", 4 ) )
    {
        dvdcss->i_method = DVDCSS_METHOD_KEY;
    }
    else if( !strncmp( psz_method, "disc", 5 ) )
    {
        dvdcss->i_method = DVDCSS_METHOD_DISC;
    }
    else if( !strncmp( psz_method, "title", 5 ) )
    {
        dvdcss->i_method = DVDCSS_METHOD_TITLE;
    }
    else
    {
        print_error( dvdcss, "unknown decrypt method, please choose "
                     "from 'title', 'key' or 'disc'" );
        return -1;
    }
    return 0;
}

192
static int set_cache_directory( dvdcss_t dvdcss )
Sam Hocevar's avatar
 
Sam Hocevar committed
193
{
194
    char *psz_cache = getenv( "DVDCSS_CACHE" );
Sam Hocevar's avatar
 
Sam Hocevar committed
195

196 197
    if( psz_cache && !strcmp( psz_cache, "off" ) )
    {
198
        return -1;
199 200
    }

201 202
    if( psz_cache == NULL || psz_cache[0] == '\0' )
    {
203
#if defined(_WIN32_IE) && _WIN32_IE >= 0x500
204
        char psz_home[PATH_MAX];
205 206 207

        /* Cache our keys in
         * C:\Documents and Settings\$USER\Application Data\dvdcss\ */
208 209
        if (SHGetFolderPathA (NULL, CSIDL_APPDATA | CSIDL_FLAG_CREATE,
                              NULL, SHGFP_TYPE_CURRENT, psz_home ) == S_OK)
210
        {
211 212 213
            snprintf( dvdcss->psz_cachefile, PATH_MAX, "%s\\dvdcss", psz_home );
            dvdcss->psz_cachefile[PATH_MAX - 1] = '\0';
            psz_cache = dvdcss->psz_cachefile;
214 215 216
        }
#else
        char *psz_home = NULL;
217
#ifdef HAVE_PWD_H
218 219 220 221 222 223 224 225
        struct passwd *p_pwd;

        /* Try looking in password file for home dir. */
        p_pwd = getpwuid(getuid());
        if( p_pwd )
        {
            psz_home = p_pwd->pw_dir;
        }
226
#endif /* HAVE_PWD_H */
227 228 229 230 231 232 233 234 235

        if( psz_home == NULL )
        {
            psz_home = getenv( "HOME" );
        }

        /* Cache our keys in ${HOME}/.dvdcss/ */
        if( psz_home )
        {
komh's avatar
komh committed
236 237
            int home_pos = 0;

238
#ifdef __OS2__
komh's avatar
komh committed
239 240
            if( *psz_home == '/' || *psz_home == '\\')
            {
241
                const char *psz_unixroot = getenv("UNIXROOT");
komh's avatar
komh committed
242 243 244 245 246 247

                if( psz_unixroot &&
                    psz_unixroot[0] &&
                    psz_unixroot[1] == ':'  &&
                    psz_unixroot[2] == '\0')
                {
248
                    strcpy( dvdcss->psz_cachefile, psz_unixroot );
komh's avatar
komh committed
249 250 251
                    home_pos = 2;
                }
            }
252
#endif /* __OS2__ */
253
            snprintf( dvdcss->psz_cachefile + home_pos, PATH_MAX - home_pos,
komh's avatar
komh committed
254
                      "%s/.dvdcss", psz_home );
255 256
            dvdcss->psz_cachefile[PATH_MAX - 1] = '\0';
            psz_cache = dvdcss->psz_cachefile;
257
        }
258
#endif /* ! defined(_WIN32_IE) && _WIN32_IE >= 0x500 */
259 260
    }

261
    /* Check that there is enough space for the cache directory path and the
262
     * block filename. The +1s are path separators. */
263
    if( psz_cache && strlen( psz_cache ) + 1 + DISC_TITLE_LENGTH + 1 +
264
        MANUFACTURING_DATE_LENGTH + 1 + STRING_KEY_SIZE + 1 +
265
        sizeof(CACHE_TAG_NAME) > PATH_MAX )
266
    {
267
        print_error( dvdcss, "cache directory name is too long" );
268
        return -1;
269
    }
270
    return 0;
271 272
}

273
static int init_cache_dir( dvdcss_t dvdcss )
274 275 276 277 278 279
{
    static const char psz_tag[] =
        "Signature: 8a477f597d28d172789f06886806bc55\r\n"
        "# This file is a cache directory tag created by libdvdcss.\r\n"
        "# For information about cache directory tags, see:\r\n"
        "#   http://www.brynosaurus.com/cachedir/\r\n";
280
    char psz_tagfile[PATH_MAX];
281 282
    int i_fd, i_ret;

283
    i_ret = mkdir( dvdcss->psz_cachefile, 0755 );
284 285 286
    if( i_ret < 0 && errno != EEXIST )
    {
        print_error( dvdcss, "failed creating cache directory" );
287 288
        dvdcss->psz_cachefile[0] = '\0';
        return -1;
289 290
    }

291
    sprintf( psz_tagfile, "%s/" CACHE_TAG_NAME, dvdcss->psz_cachefile );
292 293 294 295 296 297 298 299 300 301 302
    i_fd = open( psz_tagfile, O_RDWR|O_CREAT, 0644 );
    if( i_fd >= 0 )
    {
        ssize_t len = strlen(psz_tag);
        if( write( i_fd, psz_tag, len ) < len )
        {
            print_error( dvdcss,
                         "Error writing cache directory tag, continuing..\n" );
        }
        close( i_fd );
    }
303
    return 0;
304 305
}

306
static void create_cache_subdir( dvdcss_t dvdcss )
307 308 309 310 311 312 313 314 315 316 317 318 319
{
    uint8_t p_sector[DVDCSS_BLOCK_SIZE];
    char psz_key[STRING_KEY_SIZE + 1];
    char *psz_title;
    uint8_t *psz_serial;
    int i, i_ret;

    /* We read sector 0. If it starts with 0x000001ba (BE), we are
     * reading a VOB file, and we should not cache anything. */

    i_ret = dvdcss->pf_seek( dvdcss, 0 );
    if( i_ret != 0 )
    {
320
        goto error;
321 322 323 324 325
    }

    i_ret = dvdcss->pf_read( dvdcss, p_sector, 1 );
    if( i_ret != 1 )
    {
326
        goto error;
327 328 329 330 331
    }

    if( p_sector[0] == 0x00 && p_sector[1] == 0x00
        && p_sector[2] == 0x01 && p_sector[3] == 0xba )
    {
332
        goto error;
333 334 335 336 337 338 339 340 341
    }

    /* The data we are looking for is at sector 16 (32768 bytes):
     *  - offset 40: disc title (32 uppercase chars)
     *  - offset 813: manufacturing date + serial no (16 digits) */

    i_ret = dvdcss->pf_seek( dvdcss, INTERESTING_SECTOR );
    if( i_ret != INTERESTING_SECTOR )
    {
342
        goto error;
343 344 345 346 347
    }

    i_ret = dvdcss->pf_read( dvdcss, p_sector, 1 );
    if( i_ret != 1 )
    {
348
        goto error;
349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391
    }

    /* Get the disc title */
    psz_title = (char *)p_sector + DISC_TITLE_OFFSET;
    psz_title[DISC_TITLE_LENGTH] = '\0';

    for( i = 0; i < DISC_TITLE_LENGTH; i++ )
    {
        if( psz_title[i] <= ' ' )
        {
            psz_title[i] = '\0';
            break;
        }
        else if( psz_title[i] == '/' || psz_title[i] == '\\' )
        {
            psz_title[i] = '-';
        }
    }

    /* Get the date + serial */
    psz_serial = p_sector + MANUFACTURING_DATE_OFFSET;
    psz_serial[MANUFACTURING_DATE_LENGTH] = '\0';

    /* Check that all characters are digits, otherwise convert. */
    for( i = 0 ; i < MANUFACTURING_DATE_LENGTH ; i++ )
    {
        if( psz_serial[i] < '0' || psz_serial[i] > '9' )
        {
            char psz_tmp[MANUFACTURING_DATE_LENGTH + 1];
            sprintf( psz_tmp,
                     "%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x",
                     psz_serial[0], psz_serial[1], psz_serial[2],
                     psz_serial[3], psz_serial[4], psz_serial[5],
                     psz_serial[6], psz_serial[7] );
            memcpy( psz_serial, psz_tmp, MANUFACTURING_DATE_LENGTH );
            break;
        }
    }

    /* Get disk key, since some discs have the same title, manufacturing
     * date and serial number, but different keys. */
    if( dvdcss->b_scrambled )
    {
392
        for( i = 0; i < DVD_KEY_SIZE; i++ )
393 394 395 396 397 398 399 400 401 402 403 404
        {
            sprintf( &psz_key[i * 2], "%.2x", dvdcss->css.p_disc_key[i] );
        }
        psz_key[STRING_KEY_SIZE] = '\0';
    }
    else
    {
        psz_key[0] = 0;
    }

    /* We have a disc name or ID, we can create the cache subdirectory. */
    i = sprintf( dvdcss->psz_cachefile, "%s/%s-%s-%s",
405
                 dvdcss->psz_cachefile, psz_title, psz_serial, psz_key );
406 407 408 409
    i_ret = mkdir( dvdcss->psz_cachefile, 0755 );
    if( i_ret < 0 && errno != EEXIST )
    {
        print_error( dvdcss, "failed creating cache subdirectory" );
410
        goto error;
411 412 413 414 415 416
    }
    i += sprintf( dvdcss->psz_cachefile + i, "/");

    /* Pointer to the filename we will use. */
    dvdcss->psz_block = dvdcss->psz_cachefile + i;

417
    print_debug( dvdcss, "Content Scrambling System (CSS) key cache dir: %s",
418
                 dvdcss->psz_cachefile );
419 420 421 422
    return;

error:
    dvdcss->psz_cachefile[0] = '\0';
423 424
}

425 426 427
static void init_cache( dvdcss_t dvdcss )
{
    /* Set CSS key cache directory. */
428 429 430 431 432
    int i_ret = set_cache_directory( dvdcss );
    if ( i_ret < 0 )
    {
        return;
    }
433 434

    /* If the cache is enabled, initialize the cache directory. */
435 436
    i_ret = init_cache_dir( dvdcss );
    if ( i_ret < 0 )
437
    {
438
        return;
439 440 441
    }

    /* If the cache is enabled, create a DVD-specific subdirectory. */
442
    create_cache_subdir( dvdcss );
443 444
}

445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468
/**
 * \brief Open a DVD device or directory and return a dvdcss instance.
 *
 * \param psz_target a string containing the target name, for instance
 *        "/dev/hdc" or "E:"
 * \return a handle to a dvdcss instance or NULL on error.
 *
 * Initialize the \e libdvdcss library, open the requested DVD device or
 * directory, and return a handle to be used for all subsequent \e libdvdcss
 * calls. \e libdvdcss checks whether ioctls can be performed on the disc,
 * and when possible, the disc key is retrieved.
 */
LIBDVDCSS_EXPORT dvdcss_t dvdcss_open ( const char *psz_target )
{
    int i_ret;

    /* Allocate the library structure. */
    dvdcss_t dvdcss = malloc( sizeof( *dvdcss ) );
    if( dvdcss == NULL )
    {
        return NULL;
    }

    /* Initialize structure with default values. */
469
    dvdcss->i_pos = 0;
470 471 472 473 474 475 476 477 478 479 480 481 482 483 484
    dvdcss->p_titles = NULL;
    dvdcss->psz_device = strdup( psz_target );
    dvdcss->psz_error = "no error";
    dvdcss->i_method = DVDCSS_METHOD_KEY;
    dvdcss->psz_cachefile[0] = '\0';

    /* Set library verbosity from DVDCSS_VERBOSE environment variable. */
    set_verbosity( dvdcss );

    /* Set DVD access method from DVDCSS_METHOD environment variable. */
    if( set_access_method( dvdcss ) < 0 )
    {
        goto error;
    }

485
    /* Open device. */
486 487
    dvdcss_check_device( dvdcss );
    i_ret = dvdcss_open_device( dvdcss );
Sam Hocevar's avatar
 
Sam Hocevar committed
488 489
    if( i_ret < 0 )
    {
490
        goto error;
Sam Hocevar's avatar
 
Sam Hocevar committed
491
    }
492

493
    dvdcss->b_scrambled = 1; /* Assume the worst */
494
    dvdcss->b_ioctls = dvdcss_use_ioctls( dvdcss );
Sam Hocevar's avatar
 
Sam Hocevar committed
495

496
    if( dvdcss->b_ioctls )
Sam Hocevar's avatar
 
Sam Hocevar committed
497
    {
498
        i_ret = dvdcss_test( dvdcss );
499

500
        if( i_ret == -3 )
501
        {
502 503 504
            print_debug( dvdcss, "scrambled disc on a region-free RPC-II "
                                 "drive: possible failure, but continuing "
                                 "anyway" );
505 506
        }
        else if( i_ret < 0 )
Sam Hocevar's avatar
Sam Hocevar committed
507 508
        {
            /* Disable the CSS ioctls and hope that it works? */
509 510
            print_debug( dvdcss,
                         "could not check whether the disc was scrambled" );
Sam Hocevar's avatar
Sam Hocevar committed
511 512 513 514
            dvdcss->b_ioctls = 0;
        }
        else
        {
515 516
            print_debug( dvdcss, i_ret ? "disc is scrambled"
                                       : "disc is unscrambled" );
Sam Hocevar's avatar
Sam Hocevar committed
517 518
            dvdcss->b_scrambled = i_ret;
        }
Sam Hocevar's avatar
 
Sam Hocevar committed
519 520
    }

521
    memset( dvdcss->css.p_disc_key, 0, DVD_KEY_SIZE );
Sam Hocevar's avatar
 
Sam Hocevar committed
522
    /* If disc is CSS protected and the ioctls work, authenticate the drive */
523
    if( dvdcss->b_scrambled && dvdcss->b_ioctls )
Sam Hocevar's avatar
 
Sam Hocevar committed
524
    {
525
        i_ret = dvdcss_disckey( dvdcss );
Sam Hocevar's avatar
 
Sam Hocevar committed
526 527 528

        if( i_ret < 0 )
        {
529
            print_debug( dvdcss, "could not get disc key" );
Sam Hocevar's avatar
 
Sam Hocevar committed
530 531 532
        }
    }

533
    init_cache( dvdcss );
534

535
    /* Seek to the beginning, just for safety. */
536 537
    dvdcss->pf_seek( dvdcss, 0 );

Sam Hocevar's avatar
 
Sam Hocevar committed
538
    return dvdcss;
539 540 541 542 543

error:
    free( dvdcss->psz_device );
    free( dvdcss );
    return NULL;
Sam Hocevar's avatar
 
Sam Hocevar committed
544 545
}

546
/**
547
 * \brief Return a string containing the last error that occurred in the
548 549
 *        given \e libdvdcss instance.
 *
550 551
 * \param dvdcss a \e libdvdcss instance
 * \return a NULL-terminated string containing the last error message.
552
 *
553 554
 * Return a string with the last error message produced by \e libdvdcss.
 * Useful to conveniently format error messages in external applications.
555
 */
Diego Biurrun's avatar
Diego Biurrun committed
556
LIBDVDCSS_EXPORT const char * dvdcss_error ( const dvdcss_t dvdcss )
Sam Hocevar's avatar
 
Sam Hocevar committed
557 558 559 560
{
    return dvdcss->psz_error;
}

561 562 563
/**
 * \brief Seek in the disc and change the current key if requested.
 *
564 565
 * \param dvdcss a \e libdvdcss instance
 * \param i_blocks an absolute block offset to seek to
566
 * \param i_flags #DVDCSS_NOFLAGS, optionally ORed with one of #DVDCSS_SEEK_KEY
567 568
 *        or #DVDCSS_SEEK_MPEG
 * \return the new position in blocks or a negative value in case an error
569 570 571 572 573 574 575
 *         happened.
 *
 * This function seeks to the requested position, in logical blocks.
 *
 * You typically set \p i_flags to #DVDCSS_NOFLAGS when seeking in a .IFO.
 *
 * If #DVDCSS_SEEK_MPEG is specified in \p i_flags and if \e libdvdcss finds it
576
 * reasonable to do so (i.e., if the dvdcss method is not "title"), the current
577
 * title key will be checked and a new one will be calculated if necessary.
578
 * This flag is typically used when reading data from a .VOB file.
579
 *
580
 * If #DVDCSS_SEEK_KEY is specified, the title key will always be checked,
581
 * even with the "title" method. This flag is typically used when seeking
582 583
 * in a new title.
 */
584
LIBDVDCSS_EXPORT int dvdcss_seek ( dvdcss_t dvdcss, int i_blocks, int i_flags )
Sam Hocevar's avatar
 
Sam Hocevar committed
585 586 587
{
    /* title cracking method is too slow to be used at each seek */
    if( ( ( i_flags & DVDCSS_SEEK_MPEG )
588
             && ( dvdcss->i_method != DVDCSS_METHOD_TITLE ) )
Sam Hocevar's avatar
 
Sam Hocevar committed
589 590 591
       || ( i_flags & DVDCSS_SEEK_KEY ) )
    {
        /* check the title key */
592
        if( dvdcss_title( dvdcss, i_blocks ) )
Sam Hocevar's avatar
 
Sam Hocevar committed
593 594 595 596 597
        {
            return -1;
        }
    }

598
    return dvdcss->pf_seek( dvdcss, i_blocks );
Sam Hocevar's avatar
 
Sam Hocevar committed
599 600
}

601 602 603
/**
 * \brief Read from the disc and decrypt data if requested.
 *
604 605 606 607 608
 * \param dvdcss a \e libdvdcss instance
 * \param p_buffer a buffer that will contain the data read from the disc
 * \param i_blocks the amount of blocks to read
 * \param i_flags #DVDCSS_NOFLAGS, optionally ORed with #DVDCSS_READ_DECRYPT
 * \return the amount of blocks read or a negative value in case an
609 610
 *         error happened.
 *
611
 * Read \p i_blocks logical blocks from the DVD.
612 613 614 615 616 617 618
 *
 * You typically set \p i_flags to #DVDCSS_NOFLAGS when reading data from a
 * .IFO file on the DVD.
 *
 * If #DVDCSS_READ_DECRYPT is specified in \p i_flags, dvdcss_read() will
 * automatically decrypt scrambled sectors. This flag is typically used when
 * reading data from a .VOB file on the DVD. It has no effect on unscrambled
619
 * discs or unscrambled sectors and can be safely used on those.
620 621
 *
 * \warning dvdcss_read() expects to be able to write \p i_blocks *
622
 *          #DVDCSS_BLOCK_SIZE bytes into \p p_buffer.
623
 */
624
LIBDVDCSS_EXPORT int dvdcss_read ( dvdcss_t dvdcss, void *p_buffer,
625 626
                                          int i_blocks,
                                          int i_flags )
Sam Hocevar's avatar
 
Sam Hocevar committed
627
{
628
    uint8_t *_p_buffer = p_buffer;
Sam Hocevar's avatar
 
Sam Hocevar committed
629 630
    int i_ret, i_index;

631
    i_ret = dvdcss->pf_read( dvdcss, _p_buffer, i_blocks );
Sam Hocevar's avatar
 
Sam Hocevar committed
632 633

    if( i_ret <= 0
634
         || !dvdcss->b_scrambled
Sam Hocevar's avatar
 
Sam Hocevar committed
635 636 637 638 639
         || !(i_flags & DVDCSS_READ_DECRYPT) )
    {
        return i_ret;
    }

640
    if( ! memcmp( dvdcss->css.p_title_key, "\0\0\0\0\0", 5 ) )
Sam Hocevar's avatar
 
Sam Hocevar committed
641
    {
642
        /* For what we believe is an unencrypted title,
Sam Hocevar's avatar
Sam Hocevar committed
643
         * check that there are no encrypted blocks */
Sam Hocevar's avatar
 
Sam Hocevar committed
644 645
        for( i_index = i_ret; i_index; i_index-- )
        {
646
            if( _p_buffer[0x14] & 0x30 )
Sam Hocevar's avatar
 
Sam Hocevar committed
647
            {
648
                print_error( dvdcss, "no key but found encrypted block" );
Sam Hocevar's avatar
 
Sam Hocevar committed
649 650
                /* Only return the initial range of unscrambled blocks? */
                /* or fail completely? return 0; */
Sam Hocevar's avatar
Sam Hocevar committed
651
                break;
Sam Hocevar's avatar
 
Sam Hocevar committed
652
            }
653
            _p_buffer = _p_buffer + DVDCSS_BLOCK_SIZE;
Sam Hocevar's avatar
 
Sam Hocevar committed
654 655
        }
    }
656
    else
Sam Hocevar's avatar
 
Sam Hocevar committed
657
    {
658 659
        /* Decrypt the blocks we managed to read */
        for( i_index = i_ret; i_index; i_index-- )
Sam Hocevar's avatar
Sam Hocevar committed
660
        {
661 662 663
            dvdcss_unscramble( dvdcss->css.p_title_key, _p_buffer );
            _p_buffer[0x14] &= 0x8f;
            _p_buffer = _p_buffer + DVDCSS_BLOCK_SIZE;
Sam Hocevar's avatar
Sam Hocevar committed
664
        }
Sam Hocevar's avatar
 
Sam Hocevar committed
665
    }
666

Sam Hocevar's avatar
 
Sam Hocevar committed
667 668 669
    return i_ret;
}

670
/**
671
 * \brief Read data from the disc into multiple buffers and decrypt data if
672 673
 *        requested.
 *
674
 * \param dvdcss a \e libdvdcss instance
675
 * \param p_iovec a pointer to an array of iovec structures that will contain
676 677 678 679
 *        the data read from the disc
 * \param i_blocks the amount of blocks to read
 * \param i_flags #DVDCSS_NOFLAGS, optionally ORed with #DVDCSS_READ_DECRYPT
 * \return the amount of blocks read or a negative value in case an
680 681
 *         error happened.
 *
682
 * Read \p i_blocks logical blocks from the DVD and write them
683 684 685 686 687 688 689 690
 * to an array of iovec structures.
 *
 * You typically set \p i_flags to #DVDCSS_NOFLAGS when reading data from a
 * .IFO file on the DVD.
 *
 * If #DVDCSS_READ_DECRYPT is specified in \p i_flags, dvdcss_readv() will
 * automatically decrypt scrambled sectors. This flag is typically used when
 * reading data from a .VOB file on the DVD. It has no effect on unscrambled
691
 * discs or unscrambled sectors and can be safely used on those.
692 693
 *
 * \warning dvdcss_readv() expects to be able to write \p i_blocks *
694
 *          #DVDCSS_BLOCK_SIZE bytes into the buffers pointed by \p p_iovec.
695 696 697
 *          Moreover, all iov_len members of the iovec structures should be
 *          multiples of #DVDCSS_BLOCK_SIZE.
 */
698
LIBDVDCSS_EXPORT int dvdcss_readv ( dvdcss_t dvdcss, void *p_iovec,
699 700
                                           int i_blocks,
                                           int i_flags )
Sam Hocevar's avatar
 
Sam Hocevar committed
701
{
702
    struct iovec *_p_iovec = p_iovec;
Sam Hocevar's avatar
 
Sam Hocevar committed
703 704 705 706
    int i_ret, i_index;
    void *iov_base;
    size_t iov_len;

707
    i_ret = dvdcss->pf_readv( dvdcss, _p_iovec, i_blocks );
Sam Hocevar's avatar
 
Sam Hocevar committed
708 709

    if( i_ret <= 0
710
         || !dvdcss->b_scrambled
Sam Hocevar's avatar
 
Sam Hocevar committed
711 712 713 714 715 716
         || !(i_flags & DVDCSS_READ_DECRYPT) )
    {
        return i_ret;
    }

    /* Initialize loop for decryption */
717 718
    iov_base = _p_iovec->iov_base;
    iov_len = _p_iovec->iov_len;
Sam Hocevar's avatar
 
Sam Hocevar committed
719 720 721 722 723 724 725 726 727 728 729 730

    /* Decrypt the blocks we managed to read */
    for( i_index = i_ret; i_index; i_index-- )
    {
        /* Check that iov_len is a multiple of 2048 */
        if( iov_len & 0x7ff )
        {
            return -1;
        }

        while( iov_len == 0 )
        {
731 732 733
            _p_iovec++;
            iov_base = _p_iovec->iov_base;
            iov_len = _p_iovec->iov_len;
Sam Hocevar's avatar
 
Sam Hocevar committed
734 735
        }

736
        dvdcss_unscramble( dvdcss->css.p_title_key, iov_base );
737
        ((uint8_t*)iov_base)[0x14] &= 0x8f;
Sam Hocevar's avatar
 
Sam Hocevar committed
738

739
        iov_base = (uint8_t*)iov_base + DVDCSS_BLOCK_SIZE;
740
        iov_len -= DVDCSS_BLOCK_SIZE;
Sam Hocevar's avatar
 
Sam Hocevar committed
741 742 743 744 745
    }

    return i_ret;
}

746
/**
747
 * \brief Clean up library state and structures.
748
 *
749
 * \param dvdcss a \e libdvdcss instance
750 751
 * \return zero in case of success, a negative value otherwise.
 *
752 753
 * Close the DVD device and free all the memory allocated by \e libdvdcss.
 * On return, the #dvdcss_t is invalidated and may not be used again.
754
 */
755
LIBDVDCSS_EXPORT int dvdcss_close ( dvdcss_t dvdcss )
Sam Hocevar's avatar
 
Sam Hocevar committed
756
{
757
    struct dvd_title *p_title;
Sam Hocevar's avatar
 
Sam Hocevar committed
758 759 760 761 762 763
    int i_ret;

    /* Free our list of keys */
    p_title = dvdcss->p_titles;
    while( p_title )
    {
764
        struct dvd_title *p_tmptitle = p_title->p_next;
Sam Hocevar's avatar
 
Sam Hocevar committed
765 766 767 768
        free( p_title );
        p_title = p_tmptitle;
    }

769
    i_ret = dvdcss_close_device( dvdcss );
Sam Hocevar's avatar
 
Sam Hocevar committed
770

771
    free( dvdcss->psz_device );
Sam Hocevar's avatar
 
Sam Hocevar committed
772 773
    free( dvdcss );

774
    return i_ret;
Sam Hocevar's avatar
 
Sam Hocevar committed
775 776
}

777
/**
778
 * \brief Detect whether or not a DVD is scrambled
779 780 781 782 783 784 785 786
 *
 * \param dvdcss a \e libdvdcss instance.
 * \return 1 if the DVD is scrambled, 0 otherwise.
 */
LIBDVDCSS_EXPORT int dvdcss_is_scrambled ( dvdcss_t dvdcss )
{
    return dvdcss->b_scrambled;
}