ref: c8e2bf595185afd6835852e78e2318e9c9cbc049
dir: /src/libdvdcss.c/
/* libdvdcss.c: DVD reading library.
*
* Authors: St�phane Borel <stef@via.ecp.fr>
* Samuel Hocevar <sam@zoy.org>
* H�kan Hjort <d95hjort@dtek.chalmers.se>
*
* Copyright (C) 1998-2002 VideoLAN
* $Id: libdvdcss.c,v 1.19 2002/10/18 18:48:59 sam Exp $
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, 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, BSD/OS, BeOS, Windows 95/98, Windows NT/2000, MacOS X,
* Solaris, HP-UX and OS/2.
* \li adaptability: unlike most similar projects, libdvdcss doesn't 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 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 behaviour 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. On rare cases this may fail
* because there is not enough encrypted data on the disc to perform
* a statistical attack, but in 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.
*
*/
/*
* Preamble
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include "dvdcss/dvdcss.h"
#include "common.h"
#include "css.h"
#include "libdvdcss.h"
#include "ioctl.h"
#include "device.h"
/**
* \brief Symbol for version checks.
*
* The name of this symbol contains the library major number, which makes it
* easy to check which \e libdvdcss development headers are installed on the
* system with tools such as autoconf.
*
* The variable itself contains the exact version number of the library,
* which can be useful for specific feature needs.
*/
char * dvdcss_interface_2 = VERSION;
/**
* \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 and open the requested DVD device or
* directory. \e libdvdcss checks whether ioctls can be performed on the disc,
* and when possible, the disc key is retrieved.
*
* dvdcss_open() returns a handle to be used for all subsequent \e libdvdcss
* calls. If an error occured, NULL is returned.
*/
extern dvdcss_t dvdcss_open ( char *psz_target )
{
int i_ret;
char *psz_method = getenv( "DVDCSS_METHOD" );
char *psz_verbose = getenv( "DVDCSS_VERBOSE" );
#ifndef WIN32
char *psz_raw_device = getenv( "DVDCSS_RAW_DEVICE" );
#endif
dvdcss_t dvdcss;
/*
* Allocate the library structure
*/
dvdcss = malloc( sizeof( struct dvdcss_s ) );
if( dvdcss == NULL )
{
return NULL;
}
/*
* Initialize structure with default values
*/
#ifndef WIN32
dvdcss->i_raw_fd = -1;
#endif
dvdcss->p_titles = NULL;
dvdcss->psz_device = (char *)strdup( psz_target );
dvdcss->psz_error = "no error";
dvdcss->i_method = DVDCSS_METHOD_KEY;
dvdcss->b_debug = 0;
dvdcss->b_errors = 0;
/*
* Find verbosity from DVDCSS_VERBOSE environment variable
*/
if( psz_verbose != NULL )
{
switch( atoi( psz_verbose ) )
{
case 2:
dvdcss->b_debug = 1;
case 1:
dvdcss->b_errors = 1;
case 0:
break;
}
}
/*
* Find method from DVDCSS_METHOD environment variable
*/
if( psz_method != NULL )
{
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
{
_dvdcss_error( dvdcss, "unknown decrypt method, please choose "
"from 'title', 'key' or 'disc'" );
free( dvdcss->psz_device );
free( dvdcss );
return NULL;
}
}
/*
* Open device
*/
i_ret = _dvdcss_open( dvdcss );
if( i_ret < 0 )
{
free( dvdcss->psz_device );
free( dvdcss );
return NULL;
}
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 < 0 )
{
/* Disable the CSS ioctls and hope that it works? */
_dvdcss_debug( dvdcss,
"could not check whether the disc was scrambled" );
dvdcss->b_ioctls = 0;
}
else
{
_dvdcss_debug( dvdcss, i_ret ? "disc is scrambled"
: "disc is unscrambled" );
dvdcss->b_scrambled = i_ret;
}
}
/* 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 )
{
_dvdcss_close( dvdcss );
free( dvdcss->psz_device );
free( dvdcss );
return NULL;
}
}
#ifndef WIN32
if( psz_raw_device != NULL )
{
_dvdcss_raw_open( dvdcss, psz_raw_device );
}
#endif
return dvdcss;
}
/**
* \brief Return a string containing the latest error that occured in the
* given \e libdvdcss instance.
*
* \param dvdcss a \e libdvdcss instance.
* \return a null-terminated string containing the latest error message.
*
* This function returns a constant string containing the latest error that
* occured in \e libdvdcss. It can be used to format error messages at your
* convenience in your application.
*/
extern 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 (ie, 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.
*
* If #DVDCSS_SEEK_KEY is specified, the title key will be always checked,
* even with the "title" method. This is equivalent to using the now
* deprecated dvdcss_title() call. This flag is typically used when seeking
* in a new title.
*/
extern 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.
*
* This function reads \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 in \p p_buffer.
*/
extern 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( ((u8*)p_buffer)[0x14] & 0x30 )
{
_dvdcss_error( dvdcss, "no key but found encrypted block" );
/* Only return the initial range of unscrambled blocks? */
/* or fail completely? return 0; */
break;
}
p_buffer = (void *) ((u8 *)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 );
((u8*)p_buffer)[0x14] &= 0x8f;
p_buffer = (void *) ((u8 *)p_buffer + DVDCSS_BLOCK_SIZE);
}
}
return i_ret;
}
/**
* \brief Read 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.
*
* This function reads \p i_blocks logical blocks from the DVD and writes 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 in the buffers pointed by \p p_iovec.
* Moreover, all iov_len members of the iovec structures should be
* multiples of #DVDCSS_BLOCK_SIZE.
*/
extern int dvdcss_readv ( dvdcss_t dvdcss, void *p_iovec,
int i_blocks,
int i_flags )
{
struct iovec *_p_iovec = (struct 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 );
((u8*)iov_base)[0x14] &= 0x8f;
iov_base = (void *) ((u8*)iov_base + DVDCSS_BLOCK_SIZE);
iov_len -= DVDCSS_BLOCK_SIZE;
}
return i_ret;
}
/**
* \brief Close the DVD and clean up the library.
*
* \param dvdcss a \e libdvdcss instance.
* \return zero in case of success, a negative value otherwise.
*
* This function closes the DVD device and frees all the memory allocated
* by \e libdvdcss. On return, the #dvdcss_t is invalidated and may not be
* used again.
*/
extern 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( dvdcss );
if( i_ret < 0 )
{
return i_ret;
}
free( dvdcss->psz_device );
free( dvdcss );
return 0;
}
/*
* Deprecated. See dvdcss_seek().
*/
#undef dvdcss_title
extern int dvdcss_title ( dvdcss_t dvdcss, int i_block )
{
return _dvdcss_title( dvdcss, i_block );
}