ref: 200baa1b6bf8e808f88532c48bb875d61b2621dc
parent: e128db913818655fb274750b597bb8ac7dd668c6
author: Sam Hocevar <sam@videolan.org>
date: Wed Jul 16 17:40:01 EDT 2003
* src/css.c:
+ Workaround in CrackTitleKey for strange discs that report read errors
seemingly at random. Testcase was on Linux 2.4.20, with a region 2 RPC2
drive, and the region 1 copy of "Chasing Amy".
+ Used macros instead of numerals where appropriate.
+ Fixed spelling here and there.
--- a/src/css.c
+++ b/src/css.c
@@ -2,7 +2,7 @@
* css.c: Functions for DVD authentication and descrambling
*****************************************************************************
* Copyright (C) 1999-2001 VideoLAN
- * $Id: css.c,v 1.25 2003/05/16 22:12:48 sam Exp $
+ * $Id: css.c,v 1.26 2003/07/16 21:40:01 sam Exp $
*
* Author: St�phane Borel <stef@via.ecp.fr>
* H�kan Hjort <d95hjort@dtek.chalmers.se>
@@ -413,7 +413,7 @@
*****************************************************************************/
int _dvdcss_disckey( dvdcss_t dvdcss )
{- unsigned char p_buffer[2048];
+ unsigned char p_buffer[ DVD_DISCKEY_SIZE ];
dvd_key_t p_disc_key;
int i;
@@ -440,7 +440,7 @@
}
/* Decrypt disc key using bus key */
- for( i = 0 ; i < 2048 ; i++ )
+ for( i = 0 ; i < DVD_DISCKEY_SIZE ; i++ )
{p_buffer[ i ] ^= dvdcss->css.p_bus_key[ 4 - (i % KEY_SIZE) ];
}
@@ -498,7 +498,7 @@
*****************************************************************************/
int _dvdcss_titlekey( dvdcss_t dvdcss, int i_pos, dvd_key_t p_title_key )
{- static uint8_t p_garbage[ 2048 ]; /* static because we never read it */
+ static uint8_t p_garbage[ DVDCSS_BLOCK_SIZE ]; /* we never read it back */
uint8_t p_key[ KEY_SIZE ];
int i, i_ret = 0;
@@ -531,7 +531,7 @@
{case -1:
/* An error getting the ASF status, something must be wrong. */
- _dvdcss_debug( dvdcss, "lost ASF reqesting title key" );
+ _dvdcss_debug( dvdcss, "lost ASF requesting title key" );
ioctl_InvalidateAgid( dvdcss->i_fd, &dvdcss->css.i_agid );
i_ret = -1;
break;
@@ -539,7 +539,7 @@
case 0:
/* This might either be a title that has no key,
* or we encountered a region error. */
- _dvdcss_debug( dvdcss, "lost ASF reqesting title key" );
+ _dvdcss_debug( dvdcss, "lost ASF requesting title key" );
break;
case 1:
@@ -562,7 +562,7 @@
p_key[ i ] ^= dvdcss->css.p_bus_key[ 4 - (i % KEY_SIZE) ];
}
- /* If p_key is all zero then there realy wasn't any key pressent
+ /* If p_key is all zero then there really wasn't any key present
* even though we got to read it without an error. */
if( !( p_key[0] | p_key[1] | p_key[2] | p_key[3] | p_key[4] ) )
{@@ -614,7 +614,7 @@
int _dvdcss_unscramble( dvd_key_t p_key, uint8_t *p_sec )
{unsigned int i_t1, i_t2, i_t3, i_t4, i_t5, i_t6;
- uint8_t *p_end = p_sec + 0x800;
+ uint8_t *p_end = p_sec + DVDCSS_BLOCK_SIZE;
/* PES_scrambling_control */
if( p_sec[0x14] & 0x30)
@@ -1405,11 +1405,12 @@
static int CrackTitleKey( dvdcss_t dvdcss, int i_pos, int i_len,
dvd_key_t p_titlekey )
{- uint8_t p_buf[0x800];
+ uint8_t p_buf[ DVDCSS_BLOCK_SIZE ];
const uint8_t p_packstart[4] = { 0x00, 0x00, 0x01, 0xba };int i_reads = 0;
int i_encrypted = 0;
int b_stop_scanning = 0;
+ int b_read_error = 0;
int i_ret;
_dvdcss_debug( dvdcss, "cracking title key" );
@@ -1436,6 +1437,18 @@
{_dvdcss_debug( dvdcss, "read returned 0 (end of device?)" );
}
+ else if( !b_read_error )
+ {+ _dvdcss_debug( dvdcss, "read error, resorting to secret "
+ "arcanes to recover" );
+
+ /* Reset the drive before trying to continue */
+ _dvdcss_close( dvdcss );
+ _dvdcss_open( dvdcss );
+
+ b_read_error = 1;
+ continue;
+ }
break;
}
@@ -1486,8 +1499,10 @@
} while( !b_stop_scanning && i_len > 0);
- if( i_len <= 0 )
+ if( !b_stop_scanning )
+ {_dvdcss_debug( dvdcss, "end of title reached" );
+ }
{ /* Print some statistics. */char psz_info[128];
@@ -1522,7 +1537,7 @@
* Then it guesses that the plain text for first encrypted bytes are
* a contiuation of that pattern.
*****************************************************************************/
-static int AttackPattern( uint8_t const p_sec[0x800],
+static int AttackPattern( uint8_t const p_sec[ DVDCSS_BLOCK_SIZE ],
int i_pos, uint8_t *p_key )
{unsigned int i_best_plen = 0;
@@ -1582,13 +1597,13 @@
* DVD specifies that there must only be one type of data in every sector.
* Every sector is one pack and so must obviously be 2048 bytes long.
* For the last pice of video data before a VOBU boundary there might not
- * be exactly the right amount of data to fill a sector. They one has to
- * pad the pack to 2048 bytes. For just a few bytes this is doen in the
+ * be exactly the right amount of data to fill a sector. Then one has to
+ * pad the pack to 2048 bytes. For just a few bytes this is done in the
* header but for any large amount you insert a PES packet from the
* Padding stream. This looks like 0x00 00 01 be xx xx ff ff ...
* where xx xx is the length of the padding stream.
*****************************************************************************/
-static int AttackPadding( uint8_t const p_sec[0x800],
+static int AttackPadding( uint8_t const p_sec[ DVDCSS_BLOCK_SIZE ],
int i_pos, uint8_t *p_key )
{unsigned int i_pes_length;
@@ -1597,18 +1612,18 @@
i_pes_length = (p_sec[0x12]<<8) | p_sec[0x13];
/* Coverd by the test below but usfull for debuging. */
- if( i_pes_length == 0x800 - 0x14 ) return 0;
+ if( i_pes_length == DVDCSS_BLOCK_SIZE - 0x14 ) return 0;
/* There must be room for at least 4? bytes of padding stream,
* and it must be encrypted.
* sector size - pack/pes header - padding startcode - padding length */
- if( ( 0x800 - 0x14 - 4 - 2 - i_pes_length < 4 ) ||
+ if( ( DVDCSS_BLOCK_SIZE - 0x14 - 4 - 2 - i_pes_length < 4 ) ||
( p_sec[0x14 + i_pes_length + 0] == 0x00 &&
p_sec[0x14 + i_pes_length + 1] == 0x00 &&
p_sec[0x14 + i_pes_length + 2] == 0x01 ) )
{fprintf( stderr, "plain %d %02x:%02x:%02x:%02x (type %02x sub %02x)\n",
- 0x800 - 0x14 - 4 - 2 - i_pes_length,
+ DVDCSS_BLOCK_SIZE - 0x14 - 4 - 2 - i_pes_length,
p_sec[0x14 + i_pes_length + 0],
p_sec[0x14 + i_pes_length + 1],
p_sec[0x14 + i_pes_length + 2],
@@ -1618,7 +1633,7 @@
}
/* If we are here we know that there is a where in the pack a
- encrypted PES header is (startcode + lenght). It's never more
+ encrypted PES header is (startcode + length). It's never more
than two packets in the pack, so we 'know' the length. The
plaintext at offset (0x14 + i_pes_length) will then be
00 00 01 e0/bd/be xx xx, in the case of be the following bytes