1 |
n-ki |
689 |
/* -*- c-basic-offset: 8 -*- |
2 |
|
|
rdesktop: A Remote Desktop Protocol client. |
3 |
|
|
Protocol services - RDP decompression |
4 |
|
|
Copyright (C) Matthew Chapman 1999-2004 |
5 |
|
|
|
6 |
|
|
This program is free software; you can redistribute it and/or modify |
7 |
|
|
it under the terms of the GNU General Public License as published by |
8 |
|
|
the Free Software Foundation; either version 2 of the License, or |
9 |
|
|
(at your option) any later version. |
10 |
|
|
|
11 |
|
|
This program is distributed in the hope that it will be useful, |
12 |
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 |
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 |
|
|
GNU General Public License for more details. |
15 |
|
|
|
16 |
|
|
You should have received a copy of the GNU General Public License |
17 |
|
|
along with this program; if not, write to the Free Software |
18 |
|
|
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
19 |
|
|
*/ |
20 |
|
|
|
21 |
n-ki |
684 |
#include <stdio.h> |
22 |
|
|
#include <string.h> |
23 |
|
|
|
24 |
|
|
#include "rdesktop.h" |
25 |
|
|
|
26 |
n-ki |
687 |
/* mppc decompression */ |
27 |
n-ki |
684 |
/* http://www.faqs.org/rfcs/rfc2118.html */ |
28 |
|
|
|
29 |
n-ki |
689 |
/* Contacts: */ |
30 |
n-ki |
684 |
|
31 |
n-ki |
689 |
/* hifn contact mentioned in the faq is */ |
32 |
|
|
/* Robert Friend rfriend at hifn dot com */ |
33 |
n-ki |
684 |
|
34 |
n-ki |
689 |
/* if you have questions regarding MPPC */ |
35 |
|
|
/* our contact is */ |
36 |
|
|
/* Guus Dhaeze GDhaeze at hifn dot com */ |
37 |
n-ki |
684 |
|
38 |
n-ki |
689 |
/* Licensing: */ |
39 |
n-ki |
684 |
|
40 |
n-ki |
689 |
/* decompression is alright as long as we */ |
41 |
|
|
/* don't compress data */ |
42 |
|
|
|
43 |
|
|
/* Algorithm: */ |
44 |
|
|
|
45 |
n-ki |
687 |
/* as the rfc states the algorithm seems to */ |
46 |
|
|
/* be LZ77 with a sliding buffer */ |
47 |
|
|
/* that is empty at init. */ |
48 |
n-ki |
684 |
|
49 |
n-ki |
689 |
/* the algorithm is called LZS and is */ |
50 |
|
|
/* patented for another couple of years. */ |
51 |
n-ki |
684 |
|
52 |
n-ki |
689 |
/* more information is available in */ |
53 |
|
|
/* http://www.ietf.org/ietf/IPR/hifn-ipr-draft-friend-tls-lzs-compression.txt */ |
54 |
n-ki |
684 |
|
55 |
n-ki |
689 |
|
56 |
n-ki |
687 |
RDPCOMP g_mppc_dict; |
57 |
|
|
|
58 |
n-ki |
684 |
int |
59 |
|
|
mppc_expand(uint8 * data, uint32 clen, uint8 ctype, uint32 * roff, uint32 * rlen) |
60 |
|
|
{ |
61 |
|
|
int k, walker_len = 0, walker; |
62 |
|
|
int i = 0; |
63 |
|
|
int next_offset, match_off; |
64 |
|
|
int match_len; |
65 |
|
|
int old_offset, match_bits; |
66 |
|
|
|
67 |
n-ki |
687 |
signed char *dict = &(g_mppc_dict.hist); |
68 |
n-ki |
684 |
|
69 |
|
|
if ((ctype & RDP_MPPC_COMPRESSED) == 0) |
70 |
|
|
{ |
71 |
|
|
*roff = 0; |
72 |
|
|
*rlen = clen; |
73 |
|
|
return 0; |
74 |
|
|
} |
75 |
|
|
|
76 |
|
|
if ((ctype & RDP_MPPC_RESET) != 0) |
77 |
|
|
{ |
78 |
n-ki |
687 |
g_mppc_dict.roff = 0; |
79 |
n-ki |
684 |
} |
80 |
|
|
|
81 |
|
|
if ((ctype & RDP_MPPC_FLUSH) != 0) |
82 |
|
|
{ |
83 |
|
|
memset(dict, 0, RDP_MPPC_DICT_SIZE); |
84 |
n-ki |
687 |
g_mppc_dict.roff = 0; |
85 |
n-ki |
684 |
} |
86 |
|
|
|
87 |
|
|
*roff = 0; |
88 |
|
|
*rlen = 0; |
89 |
|
|
|
90 |
n-ki |
687 |
walker = g_mppc_dict.roff; |
91 |
n-ki |
684 |
|
92 |
|
|
next_offset = walker; |
93 |
|
|
old_offset = next_offset; |
94 |
|
|
*roff = old_offset; |
95 |
|
|
if (clen == 0) |
96 |
|
|
return 0; |
97 |
|
|
clen += i; |
98 |
|
|
|
99 |
|
|
do |
100 |
|
|
{ |
101 |
|
|
if (walker_len == 0) |
102 |
|
|
{ |
103 |
|
|
if (i >= clen) |
104 |
|
|
break; |
105 |
|
|
walker = data[i++] << 24; |
106 |
|
|
walker_len = 8; |
107 |
|
|
} |
108 |
|
|
if (walker >= 0) |
109 |
|
|
{ |
110 |
|
|
if (walker_len < 8) |
111 |
|
|
{ |
112 |
|
|
if (i >= clen) |
113 |
|
|
{ |
114 |
|
|
if (walker != 0) |
115 |
|
|
return -1; |
116 |
|
|
break; |
117 |
|
|
} |
118 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
119 |
|
|
walker_len += 8; |
120 |
|
|
} |
121 |
|
|
if (next_offset >= RDP_MPPC_DICT_SIZE) |
122 |
|
|
return -1; |
123 |
|
|
dict[next_offset++] = (((uint32) walker) >> ((uint32) 24)); |
124 |
|
|
walker <<= 8; |
125 |
|
|
walker_len -= 8; |
126 |
|
|
continue; |
127 |
|
|
} |
128 |
|
|
walker <<= 1; |
129 |
|
|
/* fetch next 8-bits */ |
130 |
|
|
if (--walker_len == 0) |
131 |
|
|
{ |
132 |
|
|
if (i >= clen) |
133 |
|
|
return -1; |
134 |
|
|
walker = data[i++] << 24; |
135 |
|
|
walker_len = 8; |
136 |
|
|
} |
137 |
|
|
/* literal decoding */ |
138 |
|
|
if (walker >= 0) |
139 |
|
|
{ |
140 |
|
|
if (walker_len < 8) |
141 |
|
|
{ |
142 |
|
|
if (i >= clen) |
143 |
|
|
return -1; |
144 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
145 |
|
|
walker_len += 8; |
146 |
|
|
} |
147 |
|
|
if (next_offset >= RDP_MPPC_DICT_SIZE) |
148 |
|
|
return -1; |
149 |
|
|
dict[next_offset++] = (uint8) (walker >> 24 | 0x80); |
150 |
|
|
walker <<= 8; |
151 |
|
|
walker_len -= 8; |
152 |
|
|
continue; |
153 |
|
|
} |
154 |
|
|
|
155 |
|
|
/* decode offset */ |
156 |
|
|
/* length pair */ |
157 |
|
|
walker <<= 1; |
158 |
|
|
if (--walker_len < 2) |
159 |
|
|
{ |
160 |
|
|
if (i >= clen) |
161 |
|
|
return -1; |
162 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
163 |
|
|
walker_len += 8; |
164 |
|
|
} |
165 |
|
|
/* offset decoding where offset len is: |
166 |
|
|
-63: 1111 followed by the lower 6 bits of the value |
167 |
|
|
64-319: 1110 followed by the lower 8 bits of the value ( value - 64 ) |
168 |
|
|
320-8191: 110 followed by the lower 13 bits of the value ( value - 320 ) |
169 |
|
|
*/ |
170 |
|
|
switch (((uint32) walker) >> ((uint32) 30)) |
171 |
|
|
{ |
172 |
|
|
case 3: /* - 63 */ |
173 |
|
|
if (walker_len < 8) |
174 |
|
|
{ |
175 |
|
|
if (i >= clen) |
176 |
|
|
return -1; |
177 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
178 |
|
|
walker_len += 8; |
179 |
|
|
} |
180 |
|
|
walker <<= 2; |
181 |
|
|
match_off = ((uint32) walker) >> ((uint32) 26); |
182 |
|
|
walker <<= 6; |
183 |
|
|
walker_len -= 8; |
184 |
|
|
break; |
185 |
|
|
|
186 |
|
|
case 2: /* 64 - 319 */ |
187 |
|
|
for (; walker_len < 10; walker_len += 8) |
188 |
|
|
{ |
189 |
|
|
if (i >= clen) |
190 |
|
|
return -1; |
191 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
192 |
|
|
} |
193 |
|
|
|
194 |
|
|
walker <<= 2; |
195 |
|
|
match_off = (((uint32) walker) >> ((uint32) 24)) + 64; |
196 |
|
|
walker <<= 8; |
197 |
|
|
walker_len -= 10; |
198 |
|
|
break; |
199 |
|
|
|
200 |
|
|
default: /* 320 - 8191 */ |
201 |
|
|
for (; walker_len < 14; walker_len += 8) |
202 |
|
|
{ |
203 |
|
|
if (i >= clen) |
204 |
|
|
return -1; |
205 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
206 |
|
|
} |
207 |
|
|
|
208 |
|
|
match_off = (walker >> 18) + 320; |
209 |
|
|
walker <<= 14; |
210 |
|
|
walker_len -= 14; |
211 |
|
|
break; |
212 |
|
|
} |
213 |
|
|
if (walker_len == 0) |
214 |
|
|
{ |
215 |
|
|
if (i >= clen) |
216 |
|
|
return -1; |
217 |
|
|
walker = data[i++] << 24; |
218 |
|
|
walker_len = 8; |
219 |
|
|
} |
220 |
|
|
|
221 |
|
|
/* decode length of match */ |
222 |
|
|
match_len = 0; |
223 |
|
|
if (walker >= 0) |
224 |
|
|
{ /* special case - length of 3 is in bit 0 */ |
225 |
|
|
match_len = 3; |
226 |
|
|
walker <<= 1; |
227 |
|
|
walker_len--; |
228 |
|
|
} |
229 |
|
|
else |
230 |
|
|
{ |
231 |
|
|
/* this is how it works len of: |
232 |
|
|
4-7: 10 followed by 2 bits of the value |
233 |
|
|
8-15: 110 followed by 3 bits of the value |
234 |
|
|
16-31: 1110 followed by 4 bits of the value |
235 |
|
|
32-63: .... and so forth |
236 |
|
|
64-127: |
237 |
|
|
128-255: |
238 |
|
|
256-511: |
239 |
|
|
512-1023: |
240 |
|
|
1024-2047: |
241 |
|
|
2048-4095: |
242 |
|
|
4096-8191: |
243 |
|
|
|
244 |
|
|
i.e. 4097 is encoded as: 111111111110 000000000001 |
245 |
|
|
meaning 4096 + 1... |
246 |
|
|
*/ |
247 |
|
|
match_bits = 11; /* 11 bits of value at most */ |
248 |
|
|
do |
249 |
|
|
{ |
250 |
|
|
walker <<= 1; |
251 |
|
|
if (--walker_len == 0) |
252 |
|
|
{ |
253 |
|
|
if (i >= clen) |
254 |
|
|
return -1; |
255 |
|
|
walker = data[i++] << 24; |
256 |
|
|
walker_len = 8; |
257 |
|
|
} |
258 |
|
|
if (walker >= 0) |
259 |
|
|
break; |
260 |
|
|
if (--match_bits == 0) |
261 |
|
|
{ |
262 |
|
|
return -1; |
263 |
|
|
} |
264 |
|
|
} |
265 |
|
|
while (1); |
266 |
|
|
match_len = 13 - match_bits; |
267 |
|
|
walker <<= 1; |
268 |
|
|
if (--walker_len < match_len) |
269 |
|
|
{ |
270 |
|
|
for (; walker_len < match_len; walker_len += 8) |
271 |
|
|
{ |
272 |
|
|
if (i >= clen) |
273 |
|
|
{ |
274 |
|
|
return -1; |
275 |
|
|
} |
276 |
|
|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
277 |
|
|
} |
278 |
|
|
} |
279 |
|
|
|
280 |
|
|
match_bits = match_len; |
281 |
|
|
match_len = |
282 |
|
|
walker >> 32 - match_bits & ~(-1 << match_bits) | 1 << match_bits; |
283 |
|
|
walker <<= match_bits; |
284 |
|
|
walker_len -= match_bits; |
285 |
|
|
} |
286 |
|
|
if (next_offset + match_len >= RDP_MPPC_DICT_SIZE) |
287 |
|
|
{ |
288 |
|
|
return -1; |
289 |
|
|
} |
290 |
|
|
/* memory areas can overlap - meaning we can't use memXXX functions */ |
291 |
|
|
k = next_offset - match_off & (RDP_MPPC_DICT_SIZE - 1); |
292 |
|
|
do |
293 |
|
|
{ |
294 |
|
|
dict[next_offset++] = dict[k++]; |
295 |
|
|
} |
296 |
|
|
while (--match_len != 0); |
297 |
|
|
} |
298 |
|
|
while (1); |
299 |
|
|
|
300 |
|
|
/* store history offset */ |
301 |
n-ki |
687 |
g_mppc_dict.roff = next_offset; |
302 |
n-ki |
684 |
|
303 |
|
|
*roff = old_offset; |
304 |
|
|
*rlen = next_offset - old_offset; |
305 |
|
|
|
306 |
|
|
return 0; |
307 |
|
|
} |