QTcpServer, listen, is the bind internal?

[SPlatten]

I have two applications one is using QTcpServer, call it App A and other is a client and uses QTcpSocket, call it App B.

A listens to Any IP on port 8123. There is a signal called newConnection which I connect to a slot:

void clsSocketServer::sayHello() {
    clsSocketClient* pClient = new clsSocketClient(nextPendingConnection());

    if ( pClient == nullptr ) {
        return;
    }
    QByteArray arybytMsg;
    QDataStream dsOut(&arybytMsg, QIODevice::WriteOnly);
    dsOut.setVersion(clsJSON::mscintQtVersion);
    QJsonObject objMsg;
    objMsg.insert(clsJSON::mscszModule, clsMainWnd::mscstrTitle);
    dsOut << QJsonDocument(objMsg).toJson(QJsonDocument::Compact);
    connect(pClient, &QAbstractSocket::disconnected
           ,pClient, &QObject::deleteLater);
    pClient->sendJSON(objMsg);
}

Application B looks for a local IP address and connects to it on the same port:

void clsModHelper::onConnectToXMLMPAM() {
    if ( isOpen() == true ) {
    //Already connected do nothing!
        return;
    }
    //Get the I/P address
    QList<QHostAddress> lstAddresses = QNetworkInterface::allAddresses();
    QString strIP;
    for( int i=0; i<lstAddresses.size(); i++ ) {
        if ( lstAddresses[i] != QHostAddress::LocalHost
          && lstAddresses[i].toIPv4Address() ) {
            strIP = lstAddresses[i].toString();
            break;
        }
    }
    if ( strIP.isEmpty() == true ) {
        strIP = QHostAddress(QHostAddress::LocalHost).toString();
    }
    //Connect to the Application
    qdbg() << "Connecting to: " << strIP << ":" << muint16XMLMPAMport;
    connectToHost(strIP, muint16XMLMPAMport);
}

When a connection from B to A is established the signal 'connected' is emitted and I can see a message is logged by the slot in application B 'onConnected':

void clsModFileIO::onConnected() {
    qdbg() << "onConnected";
}

I'm confused as application A shows no sign of the new connection, but if I terminate application A, application B gets the 'disconnected' signal, I can see that because the slot in application B:

void clsModFileIO::onDisconnected() {
    //Close the exiting connection
    close();
    //Re-open the connection
    connectToXMLMPAM();
}

I would have expected to see in Application A that the slot that is connected to the 'newConnection' signal gets called, but it does not. I'm confused about what is going on and how I can progress this?

Application A signal connections:

connect(this, &QTcpServer::newConnection, this, &clsSocketServer::sayHello);

Application B signal connections:

    QObject::connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit
                    ,this, &clsModHelper::onExitModule);
    QObject::connect(this, SIGNAL(connected()), this, SLOT(onConnected()));
    QObject::connect(this, SIGNAL(connected()), this, SLOT(onSendModuleStartupMsg()));
    QObject::connect(this, SIGNAL(connected()), this, SLOT(onStartHeartbeat()));
    QObject::connect(this, SIGNAL(disconnected()), this, SLOT(onDisconnected()));
    QObject::connect(this, &QAbstractSocket::errorOccurred, this, &clsModHelper::onErrorOccurred);
    QObject::connect(this, &QIODevice::readyRead, this, &clsModHelper::onDataIn);
    QObject::connect(this, SIGNAL(bytesWritten(qint64)), this, SLOT(onBytesWritten(qint64)));        
    QObject::connect(this, &clsModHelper::terminateModule, this, &clsModHelper::onExitModule);

Application A , log:

D00000000000000000001:XMLMPAM is listening on: 192.168.1.158:8123
D00000000000000000002:L00000141Fsimon.js[void clsScriptHelper::log]:
D00000000000000000003:************** setup ****************
D00000000000000000004:L00000116Fsimon.js[void clsScriptHelper::log]:
D00000000000000000005:************** connect ****************
D00000000000000000006:L00000062Fsimon.js[void clsScriptHelper::log]:
D00000000000000000007:L00000047Fsimon.js[QProcess *clsScriptHelper::pLaunch]:
D00000000000000000008:Checking for PID for: /Users/simonplatten/XMLMPAM/config/modules/mdFileIO
D00000000000000000009:Process: /Users/simonplatten/XMLMPAM/config/modules/mdFileIO started, PID: 80462
D00000000000000000010:L00000100Fsimon.js[void clsScriptHelper::log]:
D00000000000000000011:************** setupFIO ****************

Application B, log:

D00000000000000000001:mdFileIO Version: 1.00
D00000000000000000002:Connecting to: 192.168.1.158:8123
D00000000000000000003:onConnected
D00000000000000000004:sendJSON: 54
D00000000000000000005:clsModHelper::onBytesWritten:54
D00000000000000000006:sendJSON: 54
D00000000000000000007:clsModHelper::onBytesWritten:54
D00000000000000000008:sendJSON: 54
D00000000000000000009:clsModHelper::onBytesWritten:54
D00000000000000000010:sendJSON: 54
D00000000000000000011:clsModHelper::onBytesWritten:54
D00000000000000000012:sendJSON: 54
D00000000000000000013:clsModHelper::onBytesWritten:54
D00000000000000000014:sendJSON: 54
D00000000000000000015:clsModHelper::onBytesWritten:54

[JonB]

@SPlatten

void clsSocketServer::sayHello() {
    clsSocketClient* pClient = new clsSocketClient(nextPendingConnection());

    if ( pClient == nullptr ) {
        return;
    }

Can you please put in a qDebug() as the very first line of this slot. I don't know how the rest of your code behaves, you imply here it might fail....

[ollarch]

This post is deleted!

[JonB]

@SPlatten said in QTcpServer, listen, is the bind internal?:

There is a signal called newConnection which I connect to a slot

I'm confused as application A shows no sign of the new connection,

I would have expected to see in Application A that the slot that is connected to the 'newConnection' signal gets called, but it does not.

Among all the connects you show, I see nothing about newConnection, nor sayHello().

Sigh. Did you edit it or did I just miss it?!

connect(this, &QTcpServer::newConnection, this, &clsSocketServer::sayHello);

Are you saying the slot does not get called?

[SPlatten]

Sorry, the newConnection signal connection is in the constructor:

clsSocketServer::clsSocketServer(QObject* pParent) : QTcpServer(pParent) {
    QString strListenFailure = QString("Cannot listen to port: ") + QString::number(clsSocketServer::mscuint16port);
    listen(QHostAddress::Any, clsSocketServer::mscuint16port);
    QList<QHostAddress> lstAddresses = QNetworkInterface::allAddresses();
    QString strIP;
    for( int i=0; i<lstAddresses.size(); i++ ) {
        if ( lstAddresses[i] != QHostAddress::LocalHost
          && lstAddresses[i].toIPv4Address() ) {
            strIP = lstAddresses[i].toString();
            break;
        }
    }
    if ( strIP.isEmpty() == true ) {
        strIP = QHostAddress(QHostAddress::LocalHost).toString();
    }
    qdbg() << tr("XMLMPAM is listening on: %1:%2\n")
                .arg(strIP).arg(clsSocketServer::mscuint16port);
    QObject::connect(this, &QTcpServer::newConnection, this, &clsSocketServer::sayHello);
    Q_ASSERT_X(isListening(), "clsSocketServer::clsSocketServer", strListenFailure.toLatin1().data());
}

No it doesn't look like it is being called, however its clear that a connection is made because when I terminate Application A, application B gets disconnect signals.

[JonB]

@SPlatten

void clsSocketServer::sayHello() {
    clsSocketClient* pClient = new clsSocketClient(nextPendingConnection());

    if ( pClient == nullptr ) {
        return;
    }

Can you please put in a qDebug() as the very first line of this slot. I don't know how the rest of your code behaves, you imply here it might fail....

[SPlatten]

@JonB , Sorry, the 'newConnection' signal is being raised and the slot 'sayHello' does get called, I've just tested it again....I am not receiving the data that application B says it has transmitted and the 'bytesWritten' signal backs this up.

[JonB]

@SPlatten
That's a totally different question!

You would want to supply a completely different set of code to address this.

[SPlatten]

@JonB , will do.