mirror of
https://github.com/reactos/reactos.git
synced 2024-11-29 06:23:41 +08:00
380 lines
8.5 KiB
C
380 lines
8.5 KiB
C
/* -*- c-basic-offset: 8 -*-
|
|
rdesktop: A Remote Desktop Protocol client.
|
|
Protocol services - RDP decompression
|
|
Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
|
|
|
|
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 3 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, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
|
|
#include "precomp.h"
|
|
|
|
/* mppc decompression */
|
|
/* http://www.faqs.org/rfcs/rfc2118.html */
|
|
|
|
/* Contacts: */
|
|
|
|
/* hifn contact mentioned in the faq is */
|
|
/* Robert Friend rfriend at hifn dot com */
|
|
|
|
/* if you have questions regarding MPPC */
|
|
/* our contact is */
|
|
/* Guus Dhaeze GDhaeze at hifn dot com */
|
|
|
|
/* Licensing: */
|
|
|
|
/* decompression is alright as long as we */
|
|
/* don't compress data */
|
|
|
|
/* Algorithm: */
|
|
|
|
/* as the rfc states the algorithm seems to */
|
|
/* be LZ77 with a sliding buffer */
|
|
/* that is empty at init. */
|
|
|
|
/* the algorithm is called LZS and is */
|
|
/* patented for another couple of years. */
|
|
|
|
/* more information is available in */
|
|
/* http://www.ietf.org/ietf/IPR/hifn-ipr-draft-friend-tls-lzs-compression.txt */
|
|
|
|
|
|
RDPCOMP g_mppc_dict;
|
|
|
|
int
|
|
mppc_expand(uint8 * data, uint32 clen, uint8 ctype, uint32 * roff, uint32 * rlen)
|
|
{
|
|
int k, walker_len = 0, walker;
|
|
uint32 i = 0;
|
|
int next_offset, match_off;
|
|
int match_len;
|
|
int old_offset, match_bits;
|
|
RD_BOOL big = ctype & RDP_MPPC_BIG ? True : False;
|
|
|
|
uint8 *dict = g_mppc_dict.hist;
|
|
|
|
if ((ctype & RDP_MPPC_COMPRESSED) == 0)
|
|
{
|
|
*roff = 0;
|
|
*rlen = clen;
|
|
return 0;
|
|
}
|
|
|
|
if ((ctype & RDP_MPPC_RESET) != 0)
|
|
{
|
|
g_mppc_dict.roff = 0;
|
|
}
|
|
|
|
if ((ctype & RDP_MPPC_FLUSH) != 0)
|
|
{
|
|
memset(dict, 0, RDP_MPPC_DICT_SIZE);
|
|
g_mppc_dict.roff = 0;
|
|
}
|
|
|
|
*roff = 0;
|
|
*rlen = 0;
|
|
|
|
walker = g_mppc_dict.roff;
|
|
|
|
next_offset = walker;
|
|
old_offset = next_offset;
|
|
*roff = old_offset;
|
|
if (clen == 0)
|
|
return 0;
|
|
clen += i;
|
|
|
|
do
|
|
{
|
|
if (walker_len == 0)
|
|
{
|
|
if (i >= clen)
|
|
break;
|
|
walker = data[i++] << 24;
|
|
walker_len = 8;
|
|
}
|
|
if (walker >= 0)
|
|
{
|
|
if (walker_len < 8)
|
|
{
|
|
if (i >= clen)
|
|
{
|
|
if (walker != 0)
|
|
return -1;
|
|
break;
|
|
}
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
walker_len += 8;
|
|
}
|
|
if (next_offset >= RDP_MPPC_DICT_SIZE)
|
|
return -1;
|
|
dict[next_offset++] = (((uint32) walker) >> ((uint32) 24));
|
|
walker <<= 8;
|
|
walker_len -= 8;
|
|
continue;
|
|
}
|
|
walker <<= 1;
|
|
/* fetch next 8-bits */
|
|
if (--walker_len == 0)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker = data[i++] << 24;
|
|
walker_len = 8;
|
|
}
|
|
/* literal decoding */
|
|
if (walker >= 0)
|
|
{
|
|
if (walker_len < 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
walker_len += 8;
|
|
}
|
|
if (next_offset >= RDP_MPPC_DICT_SIZE)
|
|
return -1;
|
|
dict[next_offset++] = (uint8) (walker >> 24 | 0x80);
|
|
walker <<= 8;
|
|
walker_len -= 8;
|
|
continue;
|
|
}
|
|
|
|
/* decode offset */
|
|
/* length pair */
|
|
walker <<= 1;
|
|
if (--walker_len < (big ? 3 : 2))
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
walker_len += 8;
|
|
}
|
|
|
|
if (big)
|
|
{
|
|
/* offset decoding where offset len is:
|
|
-63: 11111 followed by the lower 6 bits of the value
|
|
64-319: 11110 followed by the lower 8 bits of the value ( value - 64 )
|
|
320-2367: 1110 followed by lower 11 bits of the value ( value - 320 )
|
|
2368-65535: 110 followed by lower 16 bits of the value ( value - 2368 )
|
|
*/
|
|
switch (((uint32) walker) >> ((uint32) 29))
|
|
{
|
|
case 7: /* - 63 */
|
|
for (; walker_len < 9; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
walker <<= 3;
|
|
match_off = ((uint32) walker) >> ((uint32) 26);
|
|
walker <<= 6;
|
|
walker_len -= 9;
|
|
break;
|
|
|
|
case 6: /* 64 - 319 */
|
|
for (; walker_len < 11; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
|
|
walker <<= 3;
|
|
match_off = (((uint32) walker) >> ((uint32) 24)) + 64;
|
|
walker <<= 8;
|
|
walker_len -= 11;
|
|
break;
|
|
|
|
case 5:
|
|
case 4: /* 320 - 2367 */
|
|
for (; walker_len < 13; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
|
|
walker <<= 2;
|
|
match_off = (((uint32) walker) >> ((uint32) 21)) + 320;
|
|
walker <<= 11;
|
|
walker_len -= 13;
|
|
break;
|
|
|
|
default: /* 2368 - 65535 */
|
|
for (; walker_len < 17; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
|
|
walker <<= 1;
|
|
match_off = (((uint32) walker) >> ((uint32) 16)) + 2368;
|
|
walker <<= 16;
|
|
walker_len -= 17;
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* offset decoding where offset len is:
|
|
-63: 1111 followed by the lower 6 bits of the value
|
|
64-319: 1110 followed by the lower 8 bits of the value ( value - 64 )
|
|
320-8191: 110 followed by the lower 13 bits of the value ( value - 320 )
|
|
*/
|
|
switch (((uint32) walker) >> ((uint32) 30))
|
|
{
|
|
case 3: /* - 63 */
|
|
if (walker_len < 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
walker_len += 8;
|
|
}
|
|
walker <<= 2;
|
|
match_off = ((uint32) walker) >> ((uint32) 26);
|
|
walker <<= 6;
|
|
walker_len -= 8;
|
|
break;
|
|
|
|
case 2: /* 64 - 319 */
|
|
for (; walker_len < 10; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
|
|
walker <<= 2;
|
|
match_off = (((uint32) walker) >> ((uint32) 24)) + 64;
|
|
walker <<= 8;
|
|
walker_len -= 10;
|
|
break;
|
|
|
|
default: /* 320 - 8191 */
|
|
for (; walker_len < 14; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
|
|
match_off = (walker >> 18) + 320;
|
|
walker <<= 14;
|
|
walker_len -= 14;
|
|
break;
|
|
}
|
|
}
|
|
if (walker_len == 0)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker = data[i++] << 24;
|
|
walker_len = 8;
|
|
}
|
|
|
|
/* decode length of match */
|
|
match_len = 0;
|
|
if (walker >= 0)
|
|
{ /* special case - length of 3 is in bit 0 */
|
|
match_len = 3;
|
|
walker <<= 1;
|
|
walker_len--;
|
|
}
|
|
else
|
|
{
|
|
/* this is how it works len of:
|
|
4-7: 10 followed by 2 bits of the value
|
|
8-15: 110 followed by 3 bits of the value
|
|
16-31: 1110 followed by 4 bits of the value
|
|
32-63: .... and so forth
|
|
64-127:
|
|
128-255:
|
|
256-511:
|
|
512-1023:
|
|
1024-2047:
|
|
2048-4095:
|
|
4096-8191:
|
|
|
|
i.e. 4097 is encoded as: 111111111110 000000000001
|
|
meaning 4096 + 1...
|
|
*/
|
|
match_bits = big ? 14 : 11; /* 11 or 14 bits of value at most */
|
|
do
|
|
{
|
|
walker <<= 1;
|
|
if (--walker_len == 0)
|
|
{
|
|
if (i >= clen)
|
|
return -1;
|
|
walker = data[i++] << 24;
|
|
walker_len = 8;
|
|
}
|
|
if (walker >= 0)
|
|
break;
|
|
if (--match_bits == 0)
|
|
{
|
|
return -1;
|
|
}
|
|
}
|
|
while (1);
|
|
match_len = (big ? 16 : 13) - match_bits;
|
|
walker <<= 1;
|
|
if (--walker_len < match_len)
|
|
{
|
|
for (; walker_len < match_len; walker_len += 8)
|
|
{
|
|
if (i >= clen)
|
|
{
|
|
return -1;
|
|
}
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len);
|
|
}
|
|
}
|
|
|
|
match_bits = match_len;
|
|
match_len =
|
|
((walker >> (32 - match_bits)) & (~(-1 << match_bits))) | (1 <<
|
|
match_bits);
|
|
walker <<= match_bits;
|
|
walker_len -= match_bits;
|
|
}
|
|
if (next_offset + match_len >= RDP_MPPC_DICT_SIZE)
|
|
{
|
|
return -1;
|
|
}
|
|
/* memory areas can overlap - meaning we can't use memXXX functions */
|
|
k = (next_offset - match_off) & (big ? 65535 : 8191);
|
|
do
|
|
{
|
|
dict[next_offset++] = dict[k++];
|
|
}
|
|
while (--match_len != 0);
|
|
}
|
|
while (1);
|
|
|
|
/* store history offset */
|
|
g_mppc_dict.roff = next_offset;
|
|
|
|
*roff = old_offset;
|
|
*rlen = next_offset - old_offset;
|
|
|
|
return 0;
|
|
}
|