Send AND receive a broadcast message

sk2212

Hello,

following code does not work:

udpSocketSend = new QUdpSocket(this);
udpSocketSend->connectToHost(QHostAddress("192.168.3.255"), 8090);
QHostAddress *host = new QHostAddress("192.168.3.2");
udpSocketGet = new QUdpSocket(this);
udpSocketGet->bind(*host, udpSocketSend->localPort());
connect(udpSocketGet, SIGNAL(readyRead()), this, SLOT(readPendingDatagrams()));
connect(startButton, SIGNAL(clicked()), this, SLOT(startBroadcasting()));
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
connect(timer, SIGNAL(timeout()), this, SLOT(broadcastDatagram()));

void Sender::readPendingDatagrams()
{
    while (udpSocketGet->hasPendingDatagrams()) {
        QByteArray datagram;
        datagram.resize(udpSocketGet->pendingDatagramSize());
        udpSocketGet->readDatagram(datagram.data(), datagram.size());
        statusLabel->setText(tr("Received datagram: \"%1\"")
                             .arg(datagram.data()));
    }
}


void Sender::broadcastDatagram()
{
    statusLabel->setText(tr("Now broadcasting datagram %1").arg(messageNo));
    QByteArray datagram = "<deviceInformationRequest/>";
    udpSocketSend->write(datagram.data(), datagram.size());
    ++messageNo;
}

In Wireshark log I can see that the write with datagram '<deviceInformationRequest/>' is performed successfully. Furthermore the devices in the network which process the datagram were responding correctly with a special response message.

The problem is now that it seems that 'readPendingDatagrams()' is never fired. Therefore I am not able to parse request message.

What is the problem? This is an extended example from given QT "Sender" Broadcast example http://doc.qt.io/qt-5/qtnetwork-broadcastsender-example.html