#include <time.h>
#ifdef WIN32
    #include <winsock.h>
    #define VENTRILO_RAND   clock()
#else
    #include <netinet/in.h>
    #include <sys/times.h>
    #define VENTRILO_RAND   times(0)
#endif



typedef struct {
    unsigned short pckkey;  // key for decoding this header
    unsigned short zero;    // ever 0
    unsigned short cmd;     // command number: 1 generic info, 2 for details
    unsigned short id;      // packet ID used for tracking the replies
    unsigned short totlen;  // total data size (for data splitted in packets)
    unsigned short len;     // size of the data in this packet (max 492)
    unsigned short totpck;  // total amount of packets (max 32)
    unsigned short pck;     // current packet number
    unsigned short datakey; // key for decoding the data
    unsigned short crc;     // checksum of the total plain-text data
} ventrilo_udp_head;



const static unsigned char  ventrilo_udp_encdata_head[] =
    "\x80\xe5\x0e\x38\xba\x63\x4c\x99\x88\x63\x4c\xd6\x54\xb8\x65\x7e"
    "\xbf\x8a\xf0\x17\x8a\xaa\x4d\x0f\xb7\x23\x27\xf6\xeb\x12\xf8\xea"
    "\x17\xb7\xcf\x52\x57\xcb\x51\xcf\x1b\x14\xfd\x6f\x84\x38\xb5\x24"
    "\x11\xcf\x7a\x75\x7a\xbb\x78\x74\xdc\xbc\x42\xf0\x17\x3f\x5e\xeb"
    "\x74\x77\x04\x4e\x8c\xaf\x23\xdc\x65\xdf\xa5\x65\xdd\x7d\xf4\x3c"
    "\x4c\x95\xbd\xeb\x65\x1c\xf4\x24\x5d\x82\x18\xfb\x50\x86\xb8\x53"
    "\xe0\x4e\x36\x96\x1f\xb7\xcb\xaa\xaf\xea\xcb\x20\x27\x30\x2a\xae"
    "\xb9\x07\x40\xdf\x12\x75\xc9\x09\x82\x9c\x30\x80\x5d\x8f\x0d\x09"
    "\xa1\x64\xec\x91\xd8\x8a\x50\x1f\x40\x5d\xf7\x08\x2a\xf8\x60\x62"
    "\xa0\x4a\x8b\xba\x4a\x6d\x00\x0a\x93\x32\x12\xe5\x07\x01\x65\xf5"
    "\xff\xe0\xae\xa7\x81\xd1\xba\x25\x62\x61\xb2\x85\xad\x7e\x9d\x3f"
    "\x49\x89\x26\xe5\xd5\xac\x9f\x0e\xd7\x6e\x47\x94\x16\x84\xc8\xff"
    "\x44\xea\x04\x40\xe0\x33\x11\xa3\x5b\x1e\x82\xff\x7a\x69\xe9\x2f"
    "\xfb\xea\x9a\xc6\x7b\xdb\xb1\xff\x97\x76\x56\xf3\x52\xc2\x3f\x0f"
    "\xb6\xac\x77\xc4\xbf\x59\x5e\x80\x74\xbb\xf2\xde\x57\x62\x4c\x1a"
    "\xff\x95\x6d\xc7\x04\xa2\x3b\xc4\x1b\x72\xc7\x6c\x82\x60\xd1\x0d";

const static unsigned char  ventrilo_udp_encdata_data[] =
    "\x82\x8b\x7f\x68\x90\xe0\x44\x09\x19\x3b\x8e\x5f\xc2\x82\x38\x23"
    "\x6d\xdb\x62\x49\x52\x6e\x21\xdf\x51\x6c\x76\x37\x86\x50\x7d\x48"
    "\x1f\x65\xe7\x52\x6a\x88\xaa\xc1\x32\x2f\xf7\x54\x4c\xaa\x6d\x7e"
    "\x6d\xa9\x8c\x0d\x3f\xff\x6c\x09\xb3\xa5\xaf\xdf\x98\x02\xb4\xbe"
    "\x6d\x69\x0d\x42\x73\xe4\x34\x50\x07\x30\x79\x41\x2f\x08\x3f\x42"
    "\x73\xa7\x68\xfa\xee\x88\x0e\x6e\xa4\x70\x74\x22\x16\xae\x3c\x81"
    "\x14\xa1\xda\x7f\xd3\x7c\x48\x7d\x3f\x46\xfb\x6d\x92\x25\x17\x36"
    "\x26\xdb\xdf\x5a\x87\x91\x6f\xd6\xcd\xd4\xad\x4a\x29\xdd\x7d\x59"
    "\xbd\x15\x34\x53\xb1\xd8\x50\x11\x83\x79\x66\x21\x9e\x87\x5b\x24"
    "\x2f\x4f\xd7\x73\x34\xa2\xf7\x09\xd5\xd9\x42\x9d\xf8\x15\xdf\x0e"
    "\x10\xcc\x05\x04\x35\x81\xb2\xd5\x7a\xd2\xa0\xa5\x7b\xb8\x75\xd2"
    "\x35\x0b\x39\x8f\x1b\x44\x0e\xce\x66\x87\x1b\x64\xac\xe1\xca\x67"
    "\xb4\xce\x33\xdb\x89\xfe\xd8\x8e\xcd\x58\x92\x41\x50\x40\xcb\x08"
    "\xe1\x15\xee\xf4\x64\xfe\x1c\xee\x25\xe7\x21\xe6\x6c\xc6\xa6\x2e"
    "\x52\x23\xa7\x20\xd2\xd7\x28\x07\x23\x14\x24\x3d\x45\xa5\xc7\x90"
    "\xdb\x77\xdd\xea\x38\x59\x89\x32\xbc\x00\x3a\x6d\x61\x4e\xdb\x29";



void ventrilo_udp_head_dec(unsigned char *data) {
    int             i;
    unsigned short  *p;
    unsigned char   a1,
                    a2;

    p = (unsigned short *)data;
    data += 2;

    *p = ntohs(*p);
    a1 = *p;
    if(!a1) return;
    a2 = *p >> 8;

    for(i = 0; i < 18; i++) {
        data[i] -= ventrilo_udp_encdata_head[a2] + (i % 5);
        a2 += a1;
    }

    for(i = 0; i < 9; i++) {
        p++;
        *p = ntohs(*p);
    }
}



void ventrilo_udp_head_enc(unsigned char *data) {
    int             i;
    unsigned short  *p;
    unsigned char   a1,
                    a2;

    p = (unsigned short *)data;
    data += 2;

    *p = (((VENTRILO_RAND * 0x343fd) + 0x269ec3) >> 16) & 0x7fff;
    a1 = *p;
    a2 = *p >> 8;
    if(!a2) {
        a2 = 69;
        *p |= (a2 << 8);
    }

    for(i = 0; i < 10; i++) {
        *p = htons(*p);
        p++;
    }

    for(i = 0; i < 18; i++) {
        data[i] += ventrilo_udp_encdata_head[a2] + (i % 5);
        a2 += a1;
    }
}



void ventrilo_udp_data_dec(unsigned char *data, int len, unsigned short key) {
    int             i;
    unsigned char   a1,
                    a2;

    a1 = key;
    if(!a1) return;
    a2 = key >> 8;

    for(i = 0; i < len; i++) {
        data[i] -= ventrilo_udp_encdata_data[a2] + (i % 72);
        a2 += a1;
    }
}



unsigned short ventrilo_udp_data_enc(unsigned char *data, int len) {
    int             i;
    unsigned short  key;
    unsigned char   a1,
                    a2;

    key = (((VENTRILO_RAND * 0x343fd) + 0x269ec3) >> 16) & 0x7fff;
    a1 = key;
    a2 = key >> 8;
    if(!a2) {
        a2 = 1;
        key |= (a2 << 8);
    }

    for(i = 0; i < len; i++) {
        data[i] += ventrilo_udp_encdata_data[a2] + (i % 72);
        a2 += a1;
    }

    return(key);
}



unsigned short ventrilo_udp_crc(unsigned char *data, int len) {
    unsigned short  crc = 0;
    const static unsigned short table[] = {
        0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
        0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
        0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
        0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
        0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
        0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
        0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
        0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
        0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
        0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
        0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
        0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
        0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
        0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
        0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
        0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
        0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
        0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
        0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
        0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
        0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
        0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
        0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
        0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
        0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
        0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
        0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
        0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
        0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
        0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
        0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
        0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
    };

    while(len--) {
        crc = table[crc >> 8] ^ *data ^ (crc << 8);
        data++;
    }

    return(crc);
}


#undef VENTRILO_RAND