Qt websocket协议的实现

 

handshake(握手)

client请求：
     GET /chat HTTP/1.1
        Host: server.example.com
        Upgrade: websocket
        Connection: Upgrade
        Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
        Sec-WebSocket-Version: 13
server回复：
     HTTP/1.1 101 Switching Protocols
        Upgrade: websocket
        Connection: Upgrade
        Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=

"dGhlIHNhbXBsZSBub25jZQ=="(Sec-WebSocket-Key)+"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"(因定GUID)
先SHA-1哈希，再用base64编码，得到"s3pPLMBiTxaQ9kYGzzhZRbK+xOo="

Framing Protocol(数据帧协议)
      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-------+-+-------------+-------------------------------+
     |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
     |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
     |N|V|V|V|       |S|             |   (if payload len==126/127)   |
     | |1|2|3|       |K|             |                               |
     +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
     |     Extended payload length continued, if payload len == 127  |
     + - - - - - - - - - - - - - - - +-------------------------------+
     |                               |Masking-key, if MASK set to 1  |
     +-------------------------------+-------------------------------+
     | Masking-key (continued)       |          Payload Data         |
     +-------------------------------- - - - - - - - - - - - - - - - +
     :                     Payload Data continued ...                :
     + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
     |                     Payload Data continued ...                |
     +---------------------------------------------------------------+
opcode:
     0x1 text frame
     0x2 binary frame
     0x8 connection close
Mask:是否有掩码(client to server必须, server to client可选)
Payload length:负载长度
     <=125 直接7位表示长度
     126，表示长充大于125并小于0xFFFF,长度放在2Byte
     127，长度放在后8Byte
Masking-key:如果有Mask,4Byte
Payload Data:如果有Mask,需要和Making-key做异或来还原数据

 

附WebSocket Protocol

http://datatracker.ietf.org/doc/rfc6455/?include_text=1

 

代码

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();
}