ReadyRead() signal in QUdpSocket isn't being triggered.

matthazley

Guys - first time coding for networking stuff so there is possibility I'm doing something silly.

I am trying to write a small UDP server application.

I have a non-Qt client transmitting to this applications socket and I have verified this is sending ok using a small UDP echo program (which echoes the data received on a port to the screen) and also, I can see the packets received in wireshark.

I am using QUdpSocket and it would appear that this Binds ok on setup - but the readyRead() signal doesn't ever seem to get triggered.

I have included some of my code below - at the minute I am simply trying to emulate the little echo program.

Just to give some context to the below code - a button press on the UI calls 'setupNewSocket' on a port that is typed in on UI.

@
#include "sockethandler.h"

SocketHandler::SocketHandler(QObject *parent) :
QObject(parent)
{
udpSocket = new QUdpSocket(this);

connect( &w, SIGNAL(openNewUDPSocket(quint16)), this, SLOT(setupNewSocket(quint16)) );
connect( this, SIGNAL(printOnUI(QString,QString,QString)), &w, SLOT(updateUI(QString,QString,QString)) );

w.show();

}

void SocketHandler::readPendingDatagrams()
{
while (udpSocket->hasPendingDatagrams())
{
QByteArray datagram;
datagram.resize(udpSocket->pendingDatagramSize());
QHostAddress sender;
quint16 senderPort;

     udpSocket->readDatagram(datagram.data(), datagram.size(), &sender, &senderPort);

     QString data = QString( datagram.data() );
     QString sender_address = sender.toString();
     QString sender_port = QString("%1").arg(senderPort);

     emit printOnUI(data, sender_address, sender_port);

}

}
void SocketHandler::setupNewSocket(quint16 port)
{
if( udpSocket->bind(QHostAddress::LocalHost, port) )
{
connect(udpSocket, SIGNAL(readyRead()), this, SLOT(readPendingDatagrams()));
}
else
{
// bind has failed
}

}
@

tomma

You bind that socket to localhost: "if( udpSocket->bind(QHostAddress::LocalHost, port) )".
So your client should be sending data to localhost too.
You should set it to QHostAddress::Any or networkinterface address to receive from network.

matthazley

Thanks - that was a silly mistake.