QUdpSocket client-server remote host not connectable

Question

I've seen few threads about my question, but, still I can't seem to solve the problem, and the replies are not sufficient. So here is the task: I have 2 PCs. One must transmit 100 udp packets, with a simple test data, and the other machine must read the datagrams. My code is as follows:

The server:

m_socket.udp = new QUdpSocket(this);

if (m_socket.udp->bind(QHostAddress("192.168.32.154"), 1234)) {
    m_socket.udp->connectToHost(QHostAddress("192.168.32.154"), 1234);
    m_socket.udp->waitForConnected();
}
connect(m_socket.udp, SIGNAL(connected()),
        this, SLOT(handleConnection()));
connect(m_socket.udp, SIGNAL(readyRead()),
        this, SLOT(readyReadUdp()));

So... first - the binding to IP of machine 1 fails. I must not specify it's IP.

The client is simple:

p_socket = new QUdpSocket(this);
p_socket->connectToHost(QHostAddress("192.168.32.94"), 1234);
connect(p_socket, SIGNAL(connected()), this, SLOT(writeDgram()));
....
void writeDgram() {
    p_socket->write(QByteArray("test"));
}

So client code, as viewed in wireshark, comes to my server machine. But my server Qt code fails me. Any help here?

Could you please be more specific? What do you see in wireshark? what do you mean by "first - the binding to IP of machine 1 fails" ? — Prabhu, Oct 24 '16 at 13:30
I am binding to remote host, ex: 192.168.32.150 with port 1234, that would be machine 1, and from 192.168.32.150 I am sending 100 datagrams to the machine that is waiting. A simple example that connects 2 UDP sockets would be great. But the example must be between 2 computers. — Ilian Zapryanov, Oct 24 '16 at 13:39
Is it that complicated to exchange few datagrams between 2 machines? No answers yet? — Ilian Zapryanov, Oct 25 '16 at 07:02
So how come that machine 1 is constantly sending UDP and wireshark catches them from machine 2, but my binding never emits the readyRead datagrams? — Ilian Zapryanov, Oct 25 '16 at 10:01

score 1 · Accepted Answer · answered Oct 28 '16 at 10:22

1

Yet, no one proposed that I can be firewalled. That was the problem. Removing the firewall solved this.

answered Oct 28 '16 at 10:22

Ilian Zapryanov

1,132
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score 0 · Answer 2 · answered Oct 24 '16 at 14:04

I've setup another udp socket to handle incoming connections that way:

    void Server::handleConnection()
{
    std::cout << "Connected to host" << std::endl;
    m_inaddr = new QUdpSocket(this);
    connect(m_inaddr, SIGNAL(readyRead()),
            this, SLOT(readyReadUdp()));

    QHostAddress addr = m_socket.udp->peerAddress();
    quint16 port = m_socket.udp->peerPort();

    bool conn = m_inaddr->bind(45678);

    if (conn) {
        m_inaddr->connectToHost(addr, port);
        std::cout << "Bound to: " << addr.toString().toStdString()
                  << " port:"
                  << port << std::endl;
    }

}

But it seems it's not working the proper way. When I am connected, I can read the peer host and port, but the auxilary socket, for inaddress must be bound to what? I am getting confused with the UDP. [EDIT] Just to add that I never break in the readyReadUdp() slot, I`ve put a breakpoint there. The reader is standart one, but the slot is never called. So I guess there is nothing ready to read.

QUdpSocket client-server remote host not connectable

2 Answers2