/* All Seeing Eye UDP packets decoding/encoding algorithm 0.1 by Luigi Auriemma e-mail: aluigi@autistici.org web: aluigi.org Introduction ============ This function is used by the program ASE to encode or decode the UDP packets sent to its servers like tracker.udpsoft.com:27246 or 194.251.249.103:27243. If sometimes you have run a sniffer during the usage of ASE you have surely noticed the UDP packets with strange bytes in them, in fact they are encoded. These packets contain your unique IDs to be included in the friends tracker or to verify your registration code when you start the program. Usually the IDs sent are MotdIdLo, MotdIdHi and UserID available in the registry key of ASE. I don't know if this algorithm is used also for other usages. How to use ========== To decode a packet: ase_udp_decenc(packet, packet_size, 0); To encode a packet: ase_udp_decenc(packet, packet_size, 1); License ======= Copyright 2005,2006 Luigi Auriemma 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 2 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, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA http://www.gnu.org/licenses/gpl.txt */ void ase_udp_decenc(unsigned char *buff, int len, int decenc) { const static unsigned int crc_table[] = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d }; const static unsigned int ase_table[] = { 0x0ff97174, 0x1f9bd468, 0x37849969, 0x4e89ae73, 0x612bf420, 0x67d79c63, 0x6d77656f, 0x745adb64, 0x7bea3365, 0x834ce620, 0x89795069, 0x8f45bf73, 0x96a87220, 0x9ec22f73, 0xa63fab74, 0xac514d6f, 0xb267656c, 0xb8413965, 0xbfe26c6e, 0xc797b620, 0xcc6a2266, 0xcf2ffb72, 0xd1fa4c6f, 0xd5eb436d, 0xd9e9a020, 0xdc48ca54, 0xdcb1b468, 0xdd11b165, 0xdd7cd620, 0xde4c6f41, 0xded49a6c, 0xdf15566c, 0xdf5a892d, 0xdfc13753, 0xe0184665, 0xe0525065, 0xe07cb969, 0xe09e356e, 0xe0d3c867, 0xe116bf20, 0xe1412945, 0xe1606979, 0xe17b3365, 0xe1a59c20, 0xe1d8f428, 0xe20c4b63, 0xe236b429, 0xe253b920, 0xe26e8355, 0xe2aac844, 0xe2c7cd50, 0xe2f6ad20, 0xe3117753, 0xe32e7c6f, 0xe3523366, 0xe37c9c74, 0xe39e1820, 0xe3d5e64c, 0xe3f76254, 0xe4146744, 0xe42cf52e, 0xe44e7120, 0xe46db168, 0xe49a5674, 0xe4c28474, 0xe4df8970, 0xe501053a, 0xe519932f, 0xe5345c2f, 0xe5633c77, 0xe5969477, 0xe5b15d77, 0xe5d09e2e, 0xe5eb6775, 0xe6063064, 0xe627ac70, 0xe64d9f73, 0xe66f1b6f, 0xe6856d66, 0xe69dfb74, 0xe6b8c42e, 0xe6d5c963, 0xe6ec1c6f, 0xe706e56d, 0xe71d3831, 0xe73c7880, 0xe7597d5b, 0xe76fcfdd, 0xe79c74df, 0xe7b502d4, 0xe7d44323, 0xe7ea95a4, 0xe80c1166, 0xe8249f5b, 0xe841a436, 0xe869d252, 0xe88024d4, 0xe898b2c8, 0xe8b140bd, 0xe8dbaa4c, 0xe8f43841, 0xe90a8ac2, 0xe920dd44, 0xe9449479, 0xe95ae6fa, 0xe977ebd6, 0xe9972c24, 0xe9ad7ea6, 0xe9c8480e, 0xe9e54ce9, 0xe9fb9f6a, 0xea142d5f, 0xea2cbb54, 0xea4784bc, 0xea5dd73d, 0xea7429be, 0xea936a0d, 0xeaa9bc8f, 0xeac24a83, 0xead89d05, 0xeaeeef86, 0xeb054207, 0xeb1b9489, 0xeb31e70a, 0xeb559e3f, 0xeb6bf0c1, 0xeb824342, 0xeb9895c3, 0xebb59a9f, 0xebcbed20, 0xebe23fa1, 0xec05f6d7, 0xec1e84cb, 0xec34d74d, 0xec4b29ce, 0xec63b7c3, 0xec7a0a44, 0xec905cc5, 0xeca6af47, 0xecbd01c8, 0xecd3544a, 0xece9a6cb, 0xecfff94c, 0xed164bce, 0xed3350a9, 0xed49a32a, 0xed62311f, 0xed7883a0, 0xed8ed622, 0xeda528a3, 0xedbb7b24, 0xedd1cda6, 0xede82027, 0xedfe72a8, 0xee14c52a, 0xee2b17ab, 0xee416a2c, 0xee57bcae, 0xee6e0f2f, 0xee8461b0, 0xee9ab432, 0xeeb106b3, 0xeec75934, 0xeeddabb6, 0xeef3fe37, 0xef0a50b9, 0xef20a33a, 0xef36f5bb, 0xef4d483d, 0xef639abe, 0xef79ed3f, 0xef903fc1, 0xefa69242, 0xefbce4c3, 0xefd33745, 0xefe989c6, 0xefffdc47, 0xf0162ec9, 0xf02c814a, 0xf042d3cb, 0xf059264d, 0xf06f78ce, 0xf08806c3, 0xf09e5944, 0xf0b4abc5, 0xf0cafe47, 0xf0e150c8, 0xf0f7a34a, 0xf10df5cb, 0xf124484c, 0xf13a9ace, 0xf150ed4f, 0xf1673fd0, 0xf17d9252, 0xf1985bba, 0xf1aeae3b, 0xf1c500bc, 0xf1db533e, 0xf1f1a5bf, 0xf207f840, 0xf21e4ac2, 0xf2349d43, 0xf24aefc4, 0xf2614246, 0xf27794c7, 0xf28de748, 0xf2a439ca, 0xf2ba8c4b, 0xf2d0decc, 0xf2e7314e, 0xf2fd83cf, 0xf313d650, 0xf32a28d2, 0xf3407b53, 0xf3590948, 0xf371973d, 0xf387e9be, 0xf39e3c3f, 0xf3b48ec1, 0xf3cd1cb5, 0xf3e36f37, 0xf3f9c1b8, 0xf4101439, 0xf42666bb, 0xf43cb93c, 0xf4530bbd, 0xf4695e3f, 0xf47fb0c0, 0xf4960341, 0xf4ac55c3, 0xf4c2a844, 0xf4d8fac5, 0xf4ef4d47, 0xf5059fc8, 0xf51bf249, 0xf53244cb, 0xf548974c, 0xf55ee9ce, 0xf5753c4f, 0xf58b8ed0, 0xf5a1e152, 0xf5b833d3, 0xf5ce8654, 0xf5e4d8d6, 0xf5fb2b57, 0xf6117dd8, 0xf627d05a, 0xf63e22db, 0xf654755c, 0xf66ac7de, 0xf6811a5f, 0xf6976ce0, 0xf6adbf62, 0xf6c411e3, 0xf6da6464, 0xffffffff }; unsigned int crc = 0, tmp, add, *pl; int i; unsigned char *p; if(!decenc) { /* DECODE */ tmp = crc = *(unsigned int *)(buff + 4); add = (crc >> 28) + 1; len >>= 2; pl = (unsigned int *)buff; for(i = 0; i < len; i++, pl++) { *pl -= ase_table[tmp & 0xff] + crc; tmp += add; } *(unsigned int *)(buff + 4) = 0; } else { /* ENCODE */ *(unsigned int *)(buff + 4) = 0; p = buff; for(i = 0; i < len; i++, p++) { crc = crc_table[(*p ^ crc) & 0xff] ^ (crc >> 8); } tmp = crc; add = (crc >> 28) + 1; len >>= 2; pl = (unsigned int *)buff; for(i = 0; i < len; i++, pl++) { *pl += ase_table[tmp & 0xff] + crc; tmp += add; } *(unsigned int *)(buff + 4) = crc; } }