dlls/jscript/decode.c

   1 /*
   2  * Copyright 2012 Jacek Caban for CodeWeavers
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  17  */
  18
  19 #include "jscript.h"
  20
  21 #include "wine/debug.h"
  22
  23 WINE_DEFAULT_DEBUG_CHANNEL(jscript);
  24
  25 /*
  26  * This file implements algorithm for decoding scripts encoded by
  27  * screnc.exe. The 'secret' algorithm that's well documented here:
  28  * http://www.virtualconspiracy.com/content/articles/breaking-screnc
  29  */
  30
  31 static const unsigned char pick_encoding[64] = {
  32     1,2,0,1,2,0,2,0,0,2,0,2,1,0,2,0,
  33     1,0,2,0,1,1,2,0,0,2,1,0,2,0,0,2,
  34     1,1,0,2,0,2,0,1,0,1,1,2,0,1,0,2,
  35     1,0,2,0,1,1,2,0,0,1,1,2,0,1,0,2};
  36
  37 static const unsigned char dictionary[][3] = {
  38     {0x00,0x00,0x00}, {0x01,0x01,0x01}, {0x02,0x02,0x02}, {0x03,0x03,0x03},
  39     {0x04,0x04,0x04}, {0x05,0x05,0x05}, {0x06,0x06,0x06}, {0x07,0x07,0x07},
  40     {0x08,0x08,0x08}, {0x7b,0x57,0x6e}, {0x0a,0x0a,0x0a}, {0x0b,0x0b,0x0b},
  41     {0x0c,0x0c,0x0c}, {0x0d,0x0d,0x0d}, {0x0e,0x0e,0x0e}, {0x0f,0x0f,0x0f},
  42     {0x10,0x10,0x10}, {0x11,0x11,0x11}, {0x12,0x12,0x12}, {0x13,0x13,0x13},
  43     {0x14,0x14,0x14}, {0x15,0x15,0x15}, {0x16,0x16,0x16}, {0x17,0x17,0x17},
  44     {0x18,0x18,0x18}, {0x19,0x19,0x19}, {0x1a,0x1a,0x1a}, {0x1b,0x1b,0x1b},
  45     {0x1c,0x1c,0x1c}, {0x1d,0x1d,0x1d}, {0x1e,0x1e,0x1e}, {0x1f,0x1f,0x1f},
  46     {0x32,0x2e,0x2d}, {0x30,0x47,0x75}, {0x21,0x7a,0x52}, {0x29,0x56,0x60},
  47     {0x5b,0x42,0x71}, {0x38,0x6a,0x5e}, {0x33,0x2f,0x49}, {0x3d,0x26,0x5c},
  48     {0x58,0x49,0x62}, {0x3a,0x41,0x7d}, {0x35,0x34,0x29}, {0x65,0x32,0x36},
  49     {0x39,0x5b,0x20}, {0x5c,0x76,0x7c}, {0x56,0x72,0x7a}, {0x73,0x43,0x7f},
  50     {0x66,0x38,0x6b}, {0x4e,0x39,0x63}, {0x45,0x70,0x33}, {0x6b,0x45,0x2b},
  51     {0x62,0x68,0x68}, {0x59,0x71,0x51}, {0x78,0x4f,0x66}, {0x5e,0x09,0x76},
  52     {0x7d,0x62,0x31}, {0x4a,0x44,0x64}, {0x6d,0x23,0x54}, {0x71,0x75,0x43},
  53     {0x00,0x00,0x00}, {0x60,0x7e,0x3a}, {0x00,0x00,0x00}, {0x53,0x5e,0x7e},
  54     {0x00,0x00,0x00}, {0x42,0x77,0x45}, {0x27,0x4a,0x2c}, {0x48,0x61,0x2a},
  55     {0x72,0x5d,0x74}, {0x75,0x22,0x27}, {0x31,0x4b,0x37}, {0x37,0x6f,0x44},
  56     {0x4d,0x4e,0x79}, {0x52,0x3b,0x59}, {0x22,0x4c,0x2f}, {0x54,0x50,0x6f},
  57     {0x6a,0x67,0x26}, {0x47,0x2a,0x72}, {0x64,0x7d,0x6a}, {0x2d,0x74,0x39},
  58     {0x20,0x54,0x7b}, {0x7f,0x2b,0x3f}, {0x2e,0x2d,0x38}, {0x4c,0x2c,0x77},
  59     {0x5d,0x30,0x67}, {0x7e,0x6e,0x53}, {0x6c,0x6b,0x47}, {0x6f,0x66,0x34},
  60     {0x79,0x35,0x78}, {0x74,0x25,0x5d}, {0x43,0x21,0x30}, {0x26,0x64,0x23},
  61     {0x76,0x4d,0x5a}, {0x25,0x52,0x5b}, {0x24,0x63,0x6c}, {0x2b,0x3f,0x48},
  62     {0x28,0x7b,0x55}, {0x23,0x78,0x70}, {0x41,0x29,0x69}, {0x34,0x28,0x2e},
  63     {0x09,0x73,0x4c}, {0x2a,0x59,0x21}, {0x44,0x33,0x24}, {0x3f,0x7f,0x4e},
  64     {0x77,0x6d,0x50}, {0x3b,0x55,0x09}, {0x55,0x53,0x56}, {0x69,0x7c,0x73},
  65     {0x61,0x3a,0x35}, {0x63,0x5f,0x61}, {0x50,0x65,0x4b}, {0x67,0x46,0x58},
  66     {0x51,0x58,0x3b}, {0x49,0x31,0x57}, {0x4f,0x69,0x22}, {0x46,0x6c,0x6d},
  67     {0x68,0x5a,0x4d}, {0x7c,0x48,0x25}, {0x36,0x27,0x28}, {0x70,0x5c,0x46},
  68     {0x6e,0x3d,0x4a}, {0x7a,0x24,0x32}, {0x2f,0x79,0x41}, {0x5f,0x37,0x3d},
  69     {0x4b,0x60,0x5f}, {0x5a,0x51,0x4f}, {0x2c,0x20,0x42}, {0x57,0x36,0x65}};
  70
  71 static const int digits[] = {
  72     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  73     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  74     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  75     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  76     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  77     0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
  78     0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
  79     0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  80     0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
  81     0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
  82     0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
  83     0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
  84     0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
  85     0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
  86     0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
  87     0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff};
  88
  89 static BOOL decode_dword(const WCHAR *p, DWORD *ret)
  90 {
  91     DWORD i;
  92
  93     for(i=0; i<6; i++) {
  94         if(p[i] >= ARRAY_SIZE(digits) || digits[p[i]] == 0xff)
  95             return FALSE;
  96     }
  97     if(p[6] != '=' || p[7] != '=')
  98         return FALSE;
  99
 100     *ret = (digits[p[0]] << 2)
 101         + (digits[p[1]] >> 4)
 102         + ((digits[p[1]] & 0xf) << 12)
 103         + ((digits[p[2]] >> 2) << 8)
 104         + ((digits[p[2]] & 0x3) << 22)
 105         + (digits[p[3]] << 16)
 106         + ((digits[p[4]] << 2) << 24)
 107         + ((digits[p[5]] >> 4) << 24);
 108     return TRUE;
 109 }
 110
 111 HRESULT decode_source(WCHAR *code)
 112 {
 113     const WCHAR *src = code;
 114     WCHAR *dst = code;
 115
 116     static const WCHAR decode_beginW[] = L"#@~^";
 117     static const WCHAR decode_endW[] = L"^#~@";
 118
 119     while(*src) {
 120         if(!wcsncmp(src, decode_beginW, ARRAY_SIZE(decode_beginW)-1)) {
 121             DWORD len, i, j=0, csum, s=0;
 122
 123             src += ARRAY_SIZE(decode_beginW) - 1;
 124
 125             if(!decode_dword(src, &len))
 126                 return JS_E_INVALID_CHAR;
 127
 128             src += 8;
 129
 130             for(i=0; i<len; i++) {
 131                 if (src[i] == '@') {
 132                     switch(src[++i]) {
 133                     case '#':
 134                         s += dst[j++] = '\r';
 135                         break;
 136                     case '&':
 137                         s += dst[j++] = '\n';
 138                         break;
 139                     case '!':
 140                         s += dst[j++] = '<';
 141                         break;
 142                     case '*':
 143                         s += dst[j++] = '>';
 144                         break;
 145                     case '$':
 146                         s += dst[j++] = '@';
 147                         break;
 148                     default:
 149                         FIXME("unescape %c\n", src[i]);
 150                         return E_FAIL;
 151                     }
 152                 }else if (src[i] < 128) {
 153                     s += dst[j] = dictionary[src[i]][pick_encoding[j%64]];
 154                     j++;
 155                 }else {
 156                     FIXME("Unsupported char %c\n", src[i]);
 157                     return E_FAIL;
 158                 }
 159             }
 160
 161             src += len;
 162             dst += j;
 163
 164             if(!decode_dword(src, &csum) || s != csum)
 165                 return JS_E_INVALID_CHAR;
 166             src += 8;
 167
 168             if(wcsncmp(src, decode_endW, ARRAY_SIZE(decode_endW)-1))
 169                 return JS_E_INVALID_CHAR;
 170             src += ARRAY_SIZE(decode_endW) - 1;
 171         }else {
 172             *dst++ = *src++;
 173         }
 174     }
 175
 176     *dst = 0;
 177
 178     TRACE("decoded %s\n", debugstr_w(code));
 179     return S_OK;
 180 }