| 1 | /* -*- c-basic-offset: 8 -*-
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| 2 | rdesktop: A Remote Desktop Protocol client.
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| 3 | Protocol services - RDP decompression
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| 4 | Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
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| 5 |
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| 6 | This program is free software: you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation, either version 3 of the License, or
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| 9 | (at your option) any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License
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| 17 | along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 18 | */
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| 19 |
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| 20 | /*
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| 21 | * Oracle GPL Disclaimer: For the avoidance of doubt, except that if any license choice
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| 22 | * other than GPL or LGPL is available it will apply instead, Oracle elects to use only
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| 23 | * the General Public License version 2 (GPLv2) at this time for any software where
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| 24 | * a choice of GPL license versions is made available with the language indicating
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| 25 | * that GPLv2 or any later version may be used, or where a choice of which version
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| 26 | * of the GPL is applied is otherwise unspecified.
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| 27 | */
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| 28 |
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| 29 | #include <stdio.h>
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| 30 | #include <string.h>
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| 31 |
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| 32 | #include "rdesktop.h"
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| 33 |
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| 34 | /* mppc decompression */
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| 35 | /* http://www.faqs.org/rfcs/rfc2118.html */
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| 36 |
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| 37 | /* Contacts: */
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| 38 |
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| 39 | /* hifn contact mentioned in the faq is */
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| 40 | /* Robert Friend rfriend at hifn dot com */
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| 41 |
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| 42 | /* if you have questions regarding MPPC */
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| 43 | /* our contact is */
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| 44 | /* Guus Dhaeze GDhaeze at hifn dot com */
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| 45 |
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| 46 | /* Licensing: */
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| 47 |
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| 48 | /* decompression is alright as long as we */
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| 49 | /* don't compress data */
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| 50 |
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| 51 | /* Algorithm: */
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| 52 |
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| 53 | /* as the rfc states the algorithm seems to */
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| 54 | /* be LZ77 with a sliding buffer */
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| 55 | /* that is empty at init. */
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| 56 |
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| 57 | /* the algorithm is called LZS and is */
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| 58 | /* patented for another couple of years. */
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| 59 |
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| 60 | /* more information is available in */
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| 61 | /* http://www.ietf.org/ietf/IPR/hifn-ipr-draft-friend-tls-lzs-compression.txt */
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| 62 |
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| 63 |
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| 64 | RDPCOMP g_mppc_dict;
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| 65 |
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| 66 | int
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| 67 | mppc_expand(uint8 * data, uint32 clen, uint8 ctype, uint32 * roff, uint32 * rlen)
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| 68 | {
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| 69 | int k, walker_len = 0, walker;
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| 70 | uint32 i = 0;
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| 71 | int next_offset, match_off;
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| 72 | int match_len;
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| 73 | int old_offset, match_bits;
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| 74 | RD_BOOL big = ctype & RDP_MPPC_BIG ? True : False;
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| 75 |
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| 76 | uint8 *dict = g_mppc_dict.hist;
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| 77 |
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| 78 | if ((ctype & RDP_MPPC_COMPRESSED) == 0)
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| 79 | {
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| 80 | *roff = 0;
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| 81 | *rlen = clen;
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| 82 | return 0;
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| 83 | }
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| 84 |
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| 85 | if ((ctype & RDP_MPPC_RESET) != 0)
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| 86 | {
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| 87 | g_mppc_dict.roff = 0;
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| 88 | }
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| 89 |
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| 90 | if ((ctype & RDP_MPPC_FLUSH) != 0)
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| 91 | {
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| 92 | memset(dict, 0, RDP_MPPC_DICT_SIZE);
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| 93 | g_mppc_dict.roff = 0;
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| 94 | }
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| 95 |
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| 96 | *roff = 0;
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| 97 | *rlen = 0;
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| 98 |
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| 99 | walker = g_mppc_dict.roff;
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| 100 |
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| 101 | next_offset = walker;
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| 102 | old_offset = next_offset;
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| 103 | *roff = old_offset;
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| 104 | if (clen == 0)
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| 105 | return 0;
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| 106 | clen += i;
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| 107 |
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| 108 | do
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| 109 | {
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| 110 | if (walker_len == 0)
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| 111 | {
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| 112 | if (i >= clen)
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| 113 | break;
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| 114 | walker = data[i++] << 24;
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| 115 | walker_len = 8;
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| 116 | }
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| 117 | if (walker >= 0)
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| 118 | {
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| 119 | if (walker_len < 8)
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| 120 | {
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| 121 | if (i >= clen)
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| 122 | {
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| 123 | if (walker != 0)
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| 124 | return -1;
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| 125 | break;
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| 126 | }
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| 127 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 128 | walker_len += 8;
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| 129 | }
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| 130 | if (next_offset >= RDP_MPPC_DICT_SIZE)
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| 131 | return -1;
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| 132 | dict[next_offset++] = (((uint32) walker) >> ((uint32) 24));
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| 133 | walker <<= 8;
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| 134 | walker_len -= 8;
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| 135 | continue;
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| 136 | }
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| 137 | walker <<= 1;
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| 138 | /* fetch next 8-bits */
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| 139 | if (--walker_len == 0)
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| 140 | {
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| 141 | if (i >= clen)
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| 142 | return -1;
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| 143 | walker = data[i++] << 24;
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| 144 | walker_len = 8;
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| 145 | }
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| 146 | /* literal decoding */
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| 147 | if (walker >= 0)
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| 148 | {
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| 149 | if (walker_len < 8)
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| 150 | {
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| 151 | if (i >= clen)
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| 152 | return -1;
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| 153 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 154 | walker_len += 8;
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| 155 | }
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| 156 | if (next_offset >= RDP_MPPC_DICT_SIZE)
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| 157 | return -1;
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| 158 | dict[next_offset++] = (uint8) (walker >> 24 | 0x80);
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| 159 | walker <<= 8;
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| 160 | walker_len -= 8;
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| 161 | continue;
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| 162 | }
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| 163 |
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| 164 | /* decode offset */
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| 165 | /* length pair */
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| 166 | walker <<= 1;
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| 167 | if (--walker_len < (big ? 3 : 2))
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| 168 | {
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| 169 | if (i >= clen)
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| 170 | return -1;
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| 171 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 172 | walker_len += 8;
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| 173 | }
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| 174 |
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| 175 | if (big)
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| 176 | {
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| 177 | /* offset decoding where offset len is:
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| 178 | -63: 11111 followed by the lower 6 bits of the value
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| 179 | 64-319: 11110 followed by the lower 8 bits of the value ( value - 64 )
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| 180 | 320-2367: 1110 followed by lower 11 bits of the value ( value - 320 )
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| 181 | 2368-65535: 110 followed by lower 16 bits of the value ( value - 2368 )
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| 182 | */
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| 183 | switch (((uint32) walker) >> ((uint32) 29))
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| 184 | {
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| 185 | case 7: /* - 63 */
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| 186 | for (; walker_len < 9; walker_len += 8)
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| 187 | {
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| 188 | if (i >= clen)
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| 189 | return -1;
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| 190 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 191 | }
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| 192 | walker <<= 3;
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| 193 | match_off = ((uint32) walker) >> ((uint32) 26);
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| 194 | walker <<= 6;
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| 195 | walker_len -= 9;
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| 196 | break;
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| 197 |
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| 198 | case 6: /* 64 - 319 */
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| 199 | for (; walker_len < 11; walker_len += 8)
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| 200 | {
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| 201 | if (i >= clen)
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| 202 | return -1;
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| 203 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 204 | }
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| 205 |
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| 206 | walker <<= 3;
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| 207 | match_off = (((uint32) walker) >> ((uint32) 24)) + 64;
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| 208 | walker <<= 8;
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| 209 | walker_len -= 11;
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| 210 | break;
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| 211 |
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| 212 | case 5:
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| 213 | case 4: /* 320 - 2367 */
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| 214 | for (; walker_len < 13; walker_len += 8)
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| 215 | {
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| 216 | if (i >= clen)
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| 217 | return -1;
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| 218 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 219 | }
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| 220 |
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| 221 | walker <<= 2;
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| 222 | match_off = (((uint32) walker) >> ((uint32) 21)) + 320;
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| 223 | walker <<= 11;
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| 224 | walker_len -= 13;
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| 225 | break;
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| 226 |
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| 227 | default: /* 2368 - 65535 */
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| 228 | for (; walker_len < 17; walker_len += 8)
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| 229 | {
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| 230 | if (i >= clen)
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| 231 | return -1;
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| 232 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 233 | }
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| 234 |
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| 235 | walker <<= 1;
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| 236 | match_off = (((uint32) walker) >> ((uint32) 16)) + 2368;
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| 237 | walker <<= 16;
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| 238 | walker_len -= 17;
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| 239 | break;
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| 240 | }
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| 241 | }
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| 242 | else
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| 243 | {
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| 244 | /* offset decoding where offset len is:
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| 245 | -63: 1111 followed by the lower 6 bits of the value
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| 246 | 64-319: 1110 followed by the lower 8 bits of the value ( value - 64 )
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| 247 | 320-8191: 110 followed by the lower 13 bits of the value ( value - 320 )
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| 248 | */
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| 249 | switch (((uint32) walker) >> ((uint32) 30))
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| 250 | {
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| 251 | case 3: /* - 63 */
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| 252 | if (walker_len < 8)
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| 253 | {
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| 254 | if (i >= clen)
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| 255 | return -1;
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| 256 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 257 | walker_len += 8;
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| 258 | }
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| 259 | walker <<= 2;
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| 260 | match_off = ((uint32) walker) >> ((uint32) 26);
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| 261 | walker <<= 6;
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| 262 | walker_len -= 8;
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| 263 | break;
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| 264 |
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| 265 | case 2: /* 64 - 319 */
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| 266 | for (; walker_len < 10; walker_len += 8)
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| 267 | {
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| 268 | if (i >= clen)
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| 269 | return -1;
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| 270 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 271 | }
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| 272 |
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| 273 | walker <<= 2;
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| 274 | match_off = (((uint32) walker) >> ((uint32) 24)) + 64;
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| 275 | walker <<= 8;
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| 276 | walker_len -= 10;
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| 277 | break;
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| 278 |
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| 279 | default: /* 320 - 8191 */
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| 280 | for (; walker_len < 14; walker_len += 8)
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| 281 | {
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| 282 | if (i >= clen)
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| 283 | return -1;
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| 284 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 285 | }
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| 286 |
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| 287 | match_off = (walker >> 18) + 320;
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| 288 | walker <<= 14;
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| 289 | walker_len -= 14;
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| 290 | break;
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| 291 | }
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| 292 | }
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| 293 | if (walker_len == 0)
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| 294 | {
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| 295 | if (i >= clen)
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| 296 | return -1;
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| 297 | walker = data[i++] << 24;
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| 298 | walker_len = 8;
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| 299 | }
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| 300 |
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| 301 | /* decode length of match */
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| 302 | match_len = 0;
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| 303 | if (walker >= 0)
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| 304 | { /* special case - length of 3 is in bit 0 */
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| 305 | match_len = 3;
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| 306 | walker <<= 1;
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| 307 | walker_len--;
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| 308 | }
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| 309 | else
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| 310 | {
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| 311 | /* this is how it works len of:
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| 312 | 4-7: 10 followed by 2 bits of the value
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| 313 | 8-15: 110 followed by 3 bits of the value
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| 314 | 16-31: 1110 followed by 4 bits of the value
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| 315 | 32-63: .... and so forth
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| 316 | 64-127:
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| 317 | 128-255:
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| 318 | 256-511:
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| 319 | 512-1023:
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| 320 | 1024-2047:
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| 321 | 2048-4095:
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| 322 | 4096-8191:
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| 323 |
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| 324 | i.e. 4097 is encoded as: 111111111110 000000000001
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| 325 | meaning 4096 + 1...
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| 326 | */
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| 327 | match_bits = big ? 14 : 11; /* 11 or 14 bits of value at most */
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| 328 | do
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| 329 | {
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| 330 | walker <<= 1;
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| 331 | if (--walker_len == 0)
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| 332 | {
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| 333 | if (i >= clen)
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| 334 | return -1;
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| 335 | walker = data[i++] << 24;
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| 336 | walker_len = 8;
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| 337 | }
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| 338 | if (walker >= 0)
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| 339 | break;
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| 340 | if (--match_bits == 0)
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| 341 | {
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| 342 | return -1;
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| 343 | }
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| 344 | }
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| 345 | while (1);
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| 346 | match_len = (big ? 16 : 13) - match_bits;
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| 347 | walker <<= 1;
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| 348 | if (--walker_len < match_len)
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| 349 | {
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| 350 | for (; walker_len < match_len; walker_len += 8)
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| 351 | {
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| 352 | if (i >= clen)
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| 353 | {
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| 354 | return -1;
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| 355 | }
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| 356 | walker |= (data[i++] & 0xff) << (24 - walker_len);
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| 357 | }
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| 358 | }
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| 359 |
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| 360 | match_bits = match_len;
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| 361 | match_len =
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| 362 | ((walker >> (32 - match_bits)) & (~(-1 << match_bits))) | (1 <<
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| 363 | match_bits);
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| 364 | walker <<= match_bits;
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| 365 | walker_len -= match_bits;
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| 366 | }
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| 367 | if (next_offset + match_len >= RDP_MPPC_DICT_SIZE)
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| 368 | {
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| 369 | return -1;
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| 370 | }
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| 371 | /* memory areas can overlap - meaning we can't use memXXX functions */
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| 372 | k = (next_offset - match_off) & (big ? 65535 : 8191);
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| 373 | do
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| 374 | {
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| 375 | dict[next_offset++] = dict[k++];
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| 376 | }
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| 377 | while (--match_len != 0);
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| 378 | }
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| 379 | while (1);
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| 380 |
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| 381 | /* store history offset */
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| 382 | g_mppc_dict.roff = next_offset;
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| 383 |
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| 384 | *roff = old_offset;
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| 385 | *rlen = next_offset - old_offset;
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| 386 |
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| 387 | return 0;
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| 388 | }
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