QByteArray handShake(QString secWebSocketKey)
{
    Q_ASSERT(!secWebSocketKey.isEmpty());
    secWebSocketKey += "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
    QString s=  QCryptographicHash::hash(secWebSocketKey.toAscii(),
                                         QCryptographicHash::Sha1).toBase64();
    QString respone = QString("HTTP/1.1 101 Switching Protocols\r\n"
                              "Upgrade: websocket\r\n"
                              "Connection: Upgrade\r\n"
                              "Access-Control-Allow-Credentials:true\r\n"
                              "Access-Control-Allow-Headers:content-type\r\n"
                              "Sec-WebSocket-Accept: %1\r\n"
                              "\r\n").arg(s);
    return respone.toAscii();
}

void unmask (int pos, int len, unsigned char *buf)
{
    int i = pos;                //The position of payload data
    int n = pos - 4;            //The position of masking-key
    for (; i<len; i++,n++)
    {
        if (n == pos) n = pos - 4;  //back to the first masking-key
        buf[i] ^= buf[n];       //unmask: payload data XOR masking-key
    }
}

QByteArray parserData(QByteArray input)
{
    unsigned char *buf=(unsigned char *)input.data();
    QByteArray out;
    int len = input.length();
    if (buf[0] == 0x88)
    {
        qDebug()<<"Received a Close frame";
        out = "close";
        return out;
    }
    buf[1] &= 0x7F;
    int payloadBegin = 0;

if (buf[1] < 126)
    {
        payloadBegin = 6;
    }
    else if (buf[1] == 126)
    {
        payloadBegin = 8; //6+2
    }
    else if (buf[1] == 127)
    {
        payloadBegin = 14;//6+8
    }
    unmask(payloadBegin, len, buf);
  
    out = QByteArray::fromRawData((const char *)(input.data()+payloadBegin), input.size()-payloadBegin);
    return out;
}

void writeData(QTcpSocket *socket, const QByteArray &data)
{
    QByteArray head(2, 0);
    if (data.length()<=125)
    {
        quint8 len = data.length();
        head[1] = len;
    }
    else if (data.length()<=0xffff)
    {
        head[1] = 126;

quint16 len = data.length();
        head.resize(4);
        for (int i=3; i>1; i--)
        {
            head[i] = (byte)(len & 0xff);
            len = len >> 8;
        }
    }
    else{
        head[1] = 127;
        quint64 len = data.length();
        head.resize(10);
        for (int i=9; i>1; i--)
        {
            head[i] = (byte)(len & 0xff);
            len = len >> 8;
        }
    }
    socket->write(head);
    socket->write(data);
    socket->flush();
}