QUdpSocket disconnects after data writing

ClingerWinger

Hello everyone! I'm trying to write a client for server (which is not mine) using QUdpSocket. But I have some problems. The main one is that socket goes to unconnected state whenever after any data was written to it.

Init socket example:

mUdpSocket = new QUdpSocket(this)

connect(mUdpSocket, &QUdpSocket::readyRead, this, &SessionManager::onSocketReadyRead);
connect(mUdpSocket, &QUdpSocket::bytesWritten, [](quint64 b) { qDebug() << "____ UDP BYTES WRITTEN:" << b; });
connect(mUdpSocket, &QUdpSocket::stateChanged, [this](QAbstractSocket::SocketState socketState) {  qDebug() << "____ UDP SOCKET STATE CHANGED:" << socketState; });

qDebug() << "____ BIND" << mUdpSocket->bind(QHostAddress::Any);

Write example:

void SessionManager::sendMessage(const QByteArray& message)
{
    if (!message.isEmpty())
    {
        mUdpSocket->writeDatagram(message, QHostAddress(mHost), G_SESSION_PORT);
        // TODO: check written != -1
    }
}

Problem occurs after calling writeDatagram. I can see that 76 bytes was written succesfully and was sent to server: signal bytesWritten reports the same amount of bytes written as in sendMessage method. I also can see with Wireshark that package was sent successfully to the server. After that socket goes to unconnected state with no error (QAbstractSocket::UnknownSocketError). At that moment I can see that server tries to send me several packages, but no readyRead signal was emmited from socket. Can someone help me? I dont know what is going wrong.

aha_1980

@ClingerWinger the most likely problem is, that your QUdpSocket is destroyed - directly or indirectly - after writeDatagram().

Its impossible to guess more from your current code, so if my answer doesnt help you you should upload the complete example so others can try it.

Regardsü

ClingerWinger

Just realised that I forgot what happened at my main.cpp. Object SessionManager was created at lambda, and destroyed there immediately. Sorry for you bother.

aha_1980

@ClingerWinger Glad you figured it out and thanks for the feedback :)