ref: aababbe6e30298c460a5837831c0e81ffbd3c2f7
dir: /src/libdvdcss.c/
/* libdvdcss.c: DVD reading library. * * Authors: Stéphane Borel <[email protected]> * Sam Hocevar <[email protected]> * Håkan Hjort <[email protected]> * * 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 <limits.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 #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 #define CACHE_TAG_NAME "CACHEDIR.TAG" #define STRING_KEY_SIZE (DVD_KEY_SIZE * 2) #define INTERESTING_SECTOR 16 #define DISC_TITLE_OFFSET 40 #define DISC_TITLE_LENGTH 32 #define MANUFACTURING_DATE_OFFSET 813 #define MANUFACTURING_DATE_LENGTH 16 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; } static int set_cache_directory( dvdcss_t dvdcss ) { char *psz_cache = getenv( "DVDCSS_CACHE" ); if( psz_cache && !strcmp( psz_cache, "off" ) ) { return -1; } 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 */ } /* Check that there is enough space for the cache directory path and the * block filename. The +1s are path separators. */ if( psz_cache && strlen( psz_cache ) + 1 + DISC_TITLE_LENGTH + 1 + MANUFACTURING_DATE_LENGTH + 1 + STRING_KEY_SIZE + 1 + sizeof(CACHE_TAG_NAME) > PATH_MAX ) { print_error( dvdcss, "cache directory name is too long" ); return -1; } return 0; } static int init_cache_dir( dvdcss_t dvdcss ) { 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]; int i_fd, i_ret; i_ret = mkdir( dvdcss->psz_cachefile, 0755 ); if( i_ret < 0 && errno != EEXIST ) { print_error( dvdcss, "failed creating cache directory" ); dvdcss->psz_cachefile[0] = '\0'; return -1; } sprintf( psz_tagfile, "%s/" CACHE_TAG_NAME, dvdcss->psz_cachefile ); 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 ); } return 0; } static void create_cache_subdir( dvdcss_t dvdcss ) { 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 ) { goto error; } i_ret = dvdcss->pf_read( dvdcss, p_sector, 1 ); if( i_ret != 1 ) { goto error; } if( p_sector[0] == 0x00 && p_sector[1] == 0x00 && p_sector[2] == 0x01 && p_sector[3] == 0xba ) { goto error; } /* 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 ) { goto error; } i_ret = dvdcss->pf_read( dvdcss, p_sector, 1 ); if( i_ret != 1 ) { goto error; } /* 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 ) { for( i = 0; i < DVD_KEY_SIZE; i++ ) { 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", dvdcss->psz_cachefile, 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" ); goto error; } i += sprintf( dvdcss->psz_cachefile + i, "/"); /* Pointer to the filename we will use. */ dvdcss->psz_block = dvdcss->psz_cachefile + i; print_debug( dvdcss, "Content Scrambling System (CSS) key cache dir: %s", dvdcss->psz_cachefile ); return; error: dvdcss->psz_cachefile[0] = '\0'; } static void init_cache( dvdcss_t dvdcss ) { /* Set CSS key cache directory. */ int i_ret = set_cache_directory( dvdcss ); if ( i_ret < 0 ) { return; } /* If the cache is enabled, initialize the cache directory. */ i_ret = init_cache_dir( dvdcss ); if ( i_ret < 0 ) { return; } /* If the cache is enabled, create a DVD-specific subdirectory. */ create_cache_subdir( dvdcss ); } /** * \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; #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. */ dvdcss->i_pos = 0; 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; } /* 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, DVD_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" ); } } init_cache( dvdcss ); #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 const char * dvdcss_error ( const 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 ) { uint8_t *_p_buffer = p_buffer; 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( _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 = _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 ); _p_buffer[0x14] &= 0x8f; _p_buffer = _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 ) { struct dvd_title *p_title; int i_ret; /* Free our list of keys */ p_title = dvdcss->p_titles; while( p_title ) { struct dvd_title *p_tmptitle = p_title->p_next; free( p_title ); p_title = p_tmptitle; } i_ret = dvdcss_close_device( dvdcss ); free( dvdcss->psz_device ); free( dvdcss ); return i_ret; } /** * \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; }