libdvdcss.c

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    {
        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 );
}