ref: e9be7c5685e562fbdc286936a4b4876c03e2afa7
dir: /src/libdvdcss.c/
/* libdvdcss.c: DVD reading library.
*
* Authors: Stéphane Borel <stef@via.ecp.fr>
* Sam Hocevar <sam@zoy.org>
* Håkan Hjort <d95hjort@dtek.chalmers.se>
*
* Copyright (C) 1998-2008 VideoLAN
*
* libdvdcss is free software; you can redistribute it and/or modify
* 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.
*
* libdvdcss is distributed in the hope that it will be useful,
* 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.
*
* You should have received a copy of the GNU General Public License along
* with libdvdcss; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* \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:
* \li portability: Currently supported platforms are GNU/Linux, FreeBSD,
* NetBSD, OpenBSD, Haiku, Mac OS X, Solaris, QNX, OS/2, and Windows
* NT 4.0 SP4 (with IE 5.0) or later.
* \li adaptability: Unlike most similar projects, libdvdcss does not require
* 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.
* \li simplicity: A DVD player can be built around the \e libdvdcss API using
* no more than 4 or 5 library calls.
*
* \e libdvdcss is free software, released under the GNU General Public License.
* 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
*
* Some environment variables can be used to change the behavior of
* \e libdvdcss without having to modify the program which uses it. These
* variables are:
*
* \li \b DVDCSS_VERBOSE: Sets the verbosity level.
* - \c 0 outputs no messages at all.
* - \c 1 outputs error messages to stderr.
* - \c 2 outputs error messages and debug messages to stderr.
*
* \li \b DVDCSS_METHOD: Sets the authentication and decryption method
* 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
* crypto attack to guess the title key. In rare cases this may fail
* because there is not enough encrypted data on the disc to perform
* a statistical attack, but on the other hand it is the only way to
* decrypt a DVD stored on a hard disc, or a DVD with the wrong region
* on an RPC2 drive.
*
* \li \b DVDCSS_RAW_DEVICE: Specify the raw device to use. Exact usage will
* 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).
*
* \li \b DVDCSS_CACHE: Specify a directory in which to cache title key
* 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
* 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.
*/
/*
* Preamble
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#ifdef HAVE_PWD_H
# include <pwd.h>
#endif
#include <fcntl.h>
#include <errno.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_LIMITS_H
# include <limits.h>
#endif
#if defined(_WIN32_IE) && _WIN32_IE >= 0x500
# include <shlobj.h>
#endif
#include "dvdcss/dvdcss.h"
#include "common.h"
#include "css.h"
#include "libdvdcss.h"
#include "ioctl.h"
#include "device.h"
#ifdef HAVE_BROKEN_MKDIR
#include <direct.h>
#define mkdir(a, b) _mkdir(a)
#endif
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;
}
}
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;
}
/**
* \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;
const char *psz_cache = getenv( "DVDCSS_CACHE" );
#ifdef DVDCSS_RAW_OPEN
const char *psz_raw_device = getenv( "DVDCSS_RAW_DEVICE" );
#endif
/* Allocate the library structure. */
dvdcss_t dvdcss = malloc( sizeof( *dvdcss ) );
if( dvdcss == NULL )
{
return NULL;
}
/* Initialize structure with default values. */
#ifdef DVDCSS_RAW_OPEN
dvdcss->i_raw_fd = -1;
#endif
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;
}
/* Set CSS key cache directory. */
if( psz_cache == NULL || psz_cache[0] == '\0' )
{
#if defined(_WIN32_IE) && _WIN32_IE >= 0x500
char psz_home[PATH_MAX];
/* Cache our keys in
* C:\Documents and Settings\$USER\Application Data\dvdcss\ */
if (SHGetFolderPathA (NULL, CSIDL_APPDATA | CSIDL_FLAG_CREATE,
NULL, SHGFP_TYPE_CURRENT, psz_home ) == S_OK)
{
snprintf( dvdcss->psz_cachefile, PATH_MAX, "%s\\dvdcss", psz_home );
dvdcss->psz_cachefile[PATH_MAX - 1] = '\0';
psz_cache = dvdcss->psz_cachefile;
}
#else
char *psz_home = NULL;
#ifdef HAVE_PWD_H
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;
}
#endif /* HAVE_PWD_H */
if( psz_home == NULL )
{
psz_home = getenv( "HOME" );
}
/* Cache our keys in ${HOME}/.dvdcss/ */
if( psz_home )
{
int home_pos = 0;
#ifdef __OS2__
if( *psz_home == '/' || *psz_home == '\\')
{
const char *psz_unixroot = getenv("UNIXROOT");
if( psz_unixroot &&
psz_unixroot[0] &&
psz_unixroot[1] == ':' &&
psz_unixroot[2] == '\0')
{
strcpy( dvdcss->psz_cachefile, psz_unixroot );
home_pos = 2;
}
}
#endif /* __OS2__ */
snprintf( dvdcss->psz_cachefile + home_pos, PATH_MAX - home_pos,
"%s/.dvdcss", psz_home );
dvdcss->psz_cachefile[PATH_MAX - 1] = '\0';
psz_cache = dvdcss->psz_cachefile;
}
#endif /* ! defined(_WIN32_IE) && _WIN32_IE >= 0x500 */
}
/* Sanity check psz_cache value. */
if( psz_cache != NULL )
{
if( psz_cache[0] == '\0' || !strcmp( psz_cache, "off" ) )
{
psz_cache = NULL;
}
/* Check that we can add the ID directory and the block filename */
else if( strlen( psz_cache ) + 1 + 32 + 1 + (KEY_SIZE * 2) + 10 + 1
> PATH_MAX )
{
print_error( dvdcss, "cache directory name is too long" );
psz_cache = NULL;
}
}
/* Open device. */
dvdcss_check_device( dvdcss );
i_ret = dvdcss_open_device( dvdcss );
if( i_ret < 0 )
{
goto error;
}
dvdcss->b_scrambled = 1; /* Assume the worst */
dvdcss->b_ioctls = dvdcss_use_ioctls( dvdcss );
if( dvdcss->b_ioctls )
{
i_ret = dvdcss_test( dvdcss );
if( i_ret == -3 )
{
print_debug( dvdcss, "scrambled disc on a region-free RPC-II "
"drive: possible failure, but continuing "
"anyway" );
}
else if( i_ret < 0 )
{
/* Disable the CSS ioctls and hope that it works? */
print_debug( dvdcss,
"could not check whether the disc was scrambled" );
dvdcss->b_ioctls = 0;
}
else
{
print_debug( dvdcss, i_ret ? "disc is scrambled"
: "disc is unscrambled" );
dvdcss->b_scrambled = i_ret;
}
}
memset( dvdcss->css.p_disc_key, 0, KEY_SIZE );
/* If disc is CSS protected and the ioctls work, authenticate the drive */
if( dvdcss->b_scrambled && dvdcss->b_ioctls )
{
i_ret = dvdcss_disckey( dvdcss );
if( i_ret < 0 )
{
print_debug( dvdcss, "could not get disc key" );
}
}
/* If the cache is enabled, write the cache directory tag */
if( psz_cache )
{
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";
char psz_tagfile[PATH_MAX + 1 + 12 + 1];
int i_fd;
i_ret = mkdir( psz_cache, 0755 );
if( i_ret < 0 && errno != EEXIST )
{
print_error( dvdcss, "failed creating cache directory" );
goto nocache;
}
sprintf( psz_tagfile, "%s/CACHEDIR.TAG", psz_cache );
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 );
}
}
/* If the cache is enabled, extract a unique disc ID */
if( psz_cache )
{
uint8_t p_sector[DVDCSS_BLOCK_SIZE];
char psz_key[1 + KEY_SIZE * 2 + 1];
char *psz_title;
uint8_t *psz_serial;
int i;
/* 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 )
{
goto nocache;
}
i_ret = dvdcss->pf_read( dvdcss, p_sector, 1 );
if( i_ret != 1 )
{
goto nocache;
}
if( p_sector[0] == 0x00 && p_sector[1] == 0x00
&& p_sector[2] == 0x01 && p_sector[3] == 0xba )
{
goto nocache;
}
/* 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, 16 );
if( i_ret != 16 )
{
goto nocache;
}
i_ret = dvdcss->pf_read( dvdcss, p_sector, 1 );
if( i_ret != 1 )
{
goto nocache;
}
/* Get the disc title */
psz_title = (char *)p_sector + 40;
psz_title[32] = '\0';
for( i = 0 ; i < 32 ; 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 + 813;
psz_serial[16] = '\0';
/* Check that all characters are digits, otherwise convert. */
for( i = 0 ; i < 16 ; i++ )
{
if( psz_serial[i] < '0' || psz_serial[i] > '9' )
{
char psz_tmp[16 + 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, 16 );
break;
}
}
/* Get disk key, since some discs have the same title, manufacturing
* date and serial number, but different keys. */
if( dvdcss->b_scrambled )
{
for( i = 0; i < KEY_SIZE; i++ )
{
sprintf( &psz_key[i * 2], "%.2x", dvdcss->css.p_disc_key[i] );
}
psz_key[KEY_SIZE * 2] = '\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",
psz_cache, psz_title, psz_serial, psz_key );
i_ret = mkdir( dvdcss->psz_cachefile, 0755 );
if( i_ret < 0 && errno != EEXIST )
{
print_error( dvdcss, "failed creating cache subdirectory" );
dvdcss->psz_cachefile[0] = '\0';
goto nocache;
}
i += sprintf( dvdcss->psz_cachefile + i, "/");
/* Pointer to the filename we will use. */
dvdcss->psz_block = dvdcss->psz_cachefile + i;
print_debug( dvdcss, "using CSS key cache dir: %s",
dvdcss->psz_cachefile );
}
nocache:
#ifdef DVDCSS_RAW_OPEN
if( psz_raw_device != NULL )
{
dvdcss_raw_open( dvdcss, psz_raw_device );
}
#endif /* DVDCSS_RAW_OPEN */
/* Seek to the beginning, just for safety. */
dvdcss->pf_seek( dvdcss, 0 );
return dvdcss;
error:
free( dvdcss->psz_device );
free( dvdcss );
return NULL;
}
/**
* \brief Return a string containing the last error that occurred in the
* given \e libdvdcss instance.
*
* \param dvdcss a \e libdvdcss instance
* \return a NULL-terminated string containing the last error message.
*
* Return a string with the last error message produced by \e libdvdcss.
* Useful to conveniently format error messages in external applications.
*/
LIBDVDCSS_EXPORT char * dvdcss_error ( dvdcss_t dvdcss )
{
return dvdcss->psz_error;
}
/**
* \brief Seek in the disc and change the current key if requested.
*
* \param dvdcss a \e libdvdcss instance
* \param i_blocks an absolute block offset to seek to
* \param i_flags #DVDCSS_NOFLAGS, optionally ORed with one of #DVDCSS_SEEK_KEY
* or #DVDCSS_SEEK_MPEG
* \return the new position in blocks or a negative value in case an error
* 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
* reasonable to do so (i.e., if the dvdcss method is not "title"), the current
* title key will be checked and a new one will be calculated if necessary.
* This flag is typically used when reading data from a .VOB file.
*
* If #DVDCSS_SEEK_KEY is specified, the title key will always be checked,
* even with the "title" method. This flag is typically used when seeking
* in a new title.
*/
LIBDVDCSS_EXPORT int dvdcss_seek ( dvdcss_t dvdcss, int i_blocks, int i_flags )
{
/* title cracking method is too slow to be used at each seek */
if( ( ( i_flags & DVDCSS_SEEK_MPEG )
&& ( dvdcss->i_method != DVDCSS_METHOD_TITLE ) )
|| ( i_flags & DVDCSS_SEEK_KEY ) )
{
/* check the title key */
if( dvdcss_title( dvdcss, i_blocks ) )
{
return -1;
}
}
return dvdcss->pf_seek( dvdcss, i_blocks );
}
/**
* \brief Read from the disc and decrypt data if requested.
*
* \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
* error happened.
*
* Read \p i_blocks logical blocks from the DVD.
*
* 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
* discs or unscrambled sectors and can be safely used on those.
*
* \warning dvdcss_read() expects to be able to write \p i_blocks *
* #DVDCSS_BLOCK_SIZE bytes into \p p_buffer.
*/
LIBDVDCSS_EXPORT int dvdcss_read ( dvdcss_t dvdcss, void *p_buffer,
int i_blocks,
int i_flags )
{
int i_ret, i_index;
i_ret = dvdcss->pf_read( dvdcss, p_buffer, i_blocks );
if( i_ret <= 0
|| !dvdcss->b_scrambled
|| !(i_flags & DVDCSS_READ_DECRYPT) )
{
return i_ret;
}
if( ! memcmp( dvdcss->css.p_title_key, "\0\0\0\0\0", 5 ) )
{
/* For what we believe is an unencrypted title,
* check that there are no encrypted blocks */
for( i_index = i_ret; i_index; i_index-- )
{
if( ((uint8_t*)p_buffer)[0x14] & 0x30 )
{
print_error( dvdcss, "no key but found encrypted block" );
/* Only return the initial range of unscrambled blocks? */
/* or fail completely? return 0; */
break;
}
p_buffer = (uint8_t *)p_buffer + DVDCSS_BLOCK_SIZE;
}
}
else
{
/* Decrypt the blocks we managed to read */
for( i_index = i_ret; i_index; i_index-- )
{
dvdcss_unscramble( dvdcss->css.p_title_key, p_buffer );
((uint8_t*)p_buffer)[0x14] &= 0x8f;
p_buffer = (uint8_t *)p_buffer + DVDCSS_BLOCK_SIZE;
}
}
return i_ret;
}
/**
* \brief Read data from the disc into multiple buffers and decrypt data if
* requested.
*
* \param dvdcss a \e libdvdcss instance
* \param p_iovec a pointer to an array of iovec structures 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
* error happened.
*
* Read \p i_blocks logical blocks from the DVD and write them
* 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
* discs or unscrambled sectors and can be safely used on those.
*
* \warning dvdcss_readv() expects to be able to write \p i_blocks *
* #DVDCSS_BLOCK_SIZE bytes into the buffers pointed by \p p_iovec.
* Moreover, all iov_len members of the iovec structures should be
* multiples of #DVDCSS_BLOCK_SIZE.
*/
LIBDVDCSS_EXPORT int dvdcss_readv ( dvdcss_t dvdcss, void *p_iovec,
int i_blocks,
int i_flags )
{
struct iovec *_p_iovec = p_iovec;
int i_ret, i_index;
void *iov_base;
size_t iov_len;
i_ret = dvdcss->pf_readv( dvdcss, _p_iovec, i_blocks );
if( i_ret <= 0
|| !dvdcss->b_scrambled
|| !(i_flags & DVDCSS_READ_DECRYPT) )
{
return i_ret;
}
/* Initialize loop for decryption */
iov_base = _p_iovec->iov_base;
iov_len = _p_iovec->iov_len;
/* 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 )
{
_p_iovec++;
iov_base = _p_iovec->iov_base;
iov_len = _p_iovec->iov_len;
}
dvdcss_unscramble( dvdcss->css.p_title_key, iov_base );
((uint8_t*)iov_base)[0x14] &= 0x8f;
iov_base = (uint8_t*)iov_base + DVDCSS_BLOCK_SIZE;
iov_len -= DVDCSS_BLOCK_SIZE;
}
return i_ret;
}
/**
* \brief Clean up library state and structures.
*
* \param dvdcss a \e libdvdcss instance
* \return zero in case of success, a negative value otherwise.
*
* 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.
*/
LIBDVDCSS_EXPORT int dvdcss_close ( dvdcss_t dvdcss )
{
dvd_title_t *p_title;
int i_ret;
/* Free our list of keys */
p_title = dvdcss->p_titles;
while( p_title )
{
dvd_title_t *p_tmptitle = p_title->p_next;
free( p_title );
p_title = p_tmptitle;
}
i_ret = dvdcss_close_device( dvdcss );
if( i_ret < 0 )
{
return i_ret;
}
free( dvdcss->psz_device );
free( dvdcss );
return 0;
}
/**
* \brief Detect whether or not a DVD is scrambled
*
* \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;
}