ref: 3979509d01dfc9f969dee80cdb9d9d962b3cbc32
dir: /src/libdvdcss.c/
/* libdvdcss.c: DVD reading library. * * Authors: St�phane Borel <[email protected]> * Samuel Hocevar <[email protected]> * H�kan Hjort <[email protected]> * * Copyright (C) 1998-2002 VideoLAN * $Id: libdvdcss.c,v 1.33 2003/06/18 17:23:55 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. 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 store 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 #ifdef HAVE_DIRECT_H # include <direct.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 ) { char psz_buffer[PATH_MAX]; int i_ret; char *psz_method = getenv( "DVDCSS_METHOD" ); char *psz_verbose = getenv( "DVDCSS_VERBOSE" ); char *psz_cache = getenv( "DVDCSS_CACHE" ); #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->psz_cachefile[0] = '\0'; dvdcss->b_debug = 0; dvdcss->b_errors = 0; /* * Find verbosity from DVDCSS_VERBOSE environment variable */ if( psz_verbose != NULL ) { int i = atoi( psz_verbose ); if( i >= 2 ) dvdcss->b_debug = 1; if( i >= 1 ) dvdcss->b_errors = 1; } /* * 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; } } /* * If DVDCSS_CACHE was not set, try to guess a default value */ if( psz_cache == NULL || psz_cache[0] == '\0' ) { #ifdef HAVE_DIRECT_H typedef HRESULT( WINAPI *SHGETFOLDERPATH ) ( HWND, int, HANDLE, DWORD, LPTSTR ); # define CSIDL_FLAG_CREATE 0x8000 # define CSIDL_APPDATA 0x1A # define SHGFP_TYPE_CURRENT 0 char psz_home[MAX_PATH]; HINSTANCE p_dll; SHGETFOLDERPATH p_getpath; *psz_home = '\0'; /* Load the shfolder dll to retrieve SHGetFolderPath */ p_dll = LoadLibrary( "shfolder.dll" ); if( p_dll ) { p_getpath = (void*)GetProcAddress( p_dll, "SHGetFolderPathA" ); if( p_getpath ) { /* Get the "Application Data" folder for the current user */ if( p_getpath( NULL, CSIDL_APPDATA | CSIDL_FLAG_CREATE, NULL, SHGFP_TYPE_CURRENT, psz_home ) == S_OK ) { FreeLibrary( p_dll ); } else { *psz_home = '\0'; } } FreeLibrary( p_dll ); } /* Cache our keys in * C:\Documents and Settings\$USER\Application Data\dvdcss\ */ if( *psz_home ) { snprintf( psz_buffer, PATH_MAX, "%s/dvdcss", psz_home ); psz_buffer[PATH_MAX-1] = '\0'; psz_cache = psz_buffer; } #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 if( psz_home == NULL ) { psz_home = getenv( "HOME" ); } /* Cache our keys in ${HOME}/.dvdcss/ */ if( psz_home ) { snprintf( psz_buffer, PATH_MAX, "%s/.dvdcss", psz_home ); psz_buffer[PATH_MAX-1] = '\0'; psz_cache = psz_buffer; } #endif } /* * Find cache dir from the DVDCSS_CACHE environment variable */ 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 + 10 + 1 > PATH_MAX ) { _dvdcss_error( dvdcss, "cache directory name is too long" ); psz_cache = 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; } } /* If the cache is enabled, extract a unique disc ID */ if( psz_cache ) { uint8_t p_sector[DVDCSS_BLOCK_SIZE]; unsigned char psz_debug[PATH_MAX+30]; unsigned char * psz_title, * 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 = 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' ) { sprintf( psz_serial, "%.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] ); break; } } /* We have a disc name or ID, we can create the cache dir */ i = sprintf( dvdcss->psz_cachefile, "%s", psz_cache ); #if !defined( WIN32 ) || defined( SYS_CYGWIN ) i_ret = mkdir( dvdcss->psz_cachefile, 0755 ); #else i_ret = mkdir( dvdcss->psz_cachefile ); #endif if( i_ret < 0 && errno != EEXIST ) { _dvdcss_error( dvdcss, "failed creating cache directory" ); dvdcss->psz_cachefile[0] = '\0'; goto nocache; } i += sprintf( dvdcss->psz_cachefile + i, "/%s#%s", psz_title, psz_serial ); #if !defined( WIN32 ) || defined( SYS_CYGWIN ) i_ret = mkdir( dvdcss->psz_cachefile, 0755 ); #else i_ret = mkdir( dvdcss->psz_cachefile ); #endif if( i_ret < 0 && errno != EEXIST ) { _dvdcss_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; sprintf( psz_debug, "using CSS key cache dir: %s", dvdcss->psz_cachefile ); _dvdcss_debug( dvdcss, psz_debug ); } nocache: #ifndef WIN32 if( psz_raw_device != NULL ) { _dvdcss_raw_open( dvdcss, psz_raw_device ); } #endif /* Seek at the beginning, just for safety. */ dvdcss->pf_seek( dvdcss, 0 ); 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( ((uint8_t*)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 *) ((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 = (void *) ((uint8_t *)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 ); ((uint8_t*)iov_base)[0x14] &= 0x8f; iov_base = (void *) ((uint8_t*)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 ); }