Connection to server fails in qt - c++

Question

I created a small server/client application, and for testing I put the server/client function into a separate application.
The main client functions are
Client::Client(QString purpose) : networkSession(0)
{
Client::purpose = purpose;
tcpSocket = new QTcpSocket;
Client::blockSize = 0;
connect(tcpSocket, SIGNAL(readyRead()), this, SLOT(readData()));
connect(tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
this, SLOT(displayError(QAbstractSocket::SocketError)));
QNetworkConfigurationManager manager;
if (manager.capabilities() & QNetworkConfigurationManager::NetworkSessionRequired)
{
// Get saved network configuration
QSettings settings(QSettings::UserScope, QLatin1String("QtProject"));
settings.beginGroup(QLatin1String("QtNetwork"));
const QString id = settings.value(QLatin1String("DefaultNetworkConfiguration")).toString();
settings.endGroup();
// If the saved network configuration is not currently discovered use the system default
QNetworkConfiguration config = manager.configurationFromIdentifier(id);
if ((config.state() & QNetworkConfiguration::Discovered) !=
QNetworkConfiguration::Discovered) {
config = manager.defaultConfiguration();
}
networkSession = new QNetworkSession(config, this);
connect(networkSession, SIGNAL(opened()), this, SLOT(sessionOpened()));
}
qDebug() << "Client set up, waiting";
}
void Client::connectToServer(QString ipAddr, quint32 port)
{
qDebug() << "Connecting to Host on port " << port << ' ' << (quint16)port;
tcpSocket->connectToHost(ipAddr, port);
emit this->connectionResult((tcpSocket->state() == QAbstractSocket::UnconnectedState)?false:true);
if (tcpSocket->waitForConnected(1000))
qDebug("Connected!");
qDebug() << "Am I connected" << tcpSocket->state();
std::cout << "Am I not connected" << tcpSocket->state();
}
and the server-functions:
Server::Server(QString ipAddr, quint32 port, QString purpose)
: tcpServer(0), networkSession(0)
{
Server::clientConnection = NULL;
Server::purpose = purpose;
Server::port = port;
QNetworkConfigurationManager manager;
if (manager.capabilities() & QNetworkConfigurationManager::NetworkSessionRequired) {
// Get saved network configuration
QSettings settings(QSettings::UserScope, QLatin1String("QtProject"));
settings.beginGroup(QLatin1String("QtNetwork"));
const QString id = settings.value(QLatin1String("DefaultNetworkConfiguration")).toString();
settings.endGroup();
// If the saved network configuration is not currently discovered use the system default
QNetworkConfiguration config = manager.configurationFromIdentifier(id);
if ((config.state() & QNetworkConfiguration::Discovered) !=
QNetworkConfiguration::Discovered) {
config = manager.defaultConfiguration();
}
networkSession = new QNetworkSession(config, this);
connect(networkSession, SIGNAL(opened()), this, SLOT(sessionOpened()));
//statusLabel->setText(tr("Opening network session."));
networkSession->open();
} else {
sessionOpened();
}
//connect(tcpServer, SIGNAL(newConnection()), this, SLOT(sendFortune()));
connect(tcpServer, SIGNAL(newConnection()), this, SLOT(openNewConnection()));
//connect(tcpServer, &QTcpServer::newConnection, this, &Server::openNewConnection);
}
void Server::sessionOpened()
{
// Save the used configuration
if (networkSession) {
QNetworkConfiguration config = networkSession->configuration();
QString id;
if (config.type() == QNetworkConfiguration::UserChoice)
id = networkSession->sessionProperty(QLatin1String("UserChoiceConfiguration")).toString();
else
id = config.identifier();
QSettings settings(QSettings::UserScope, QLatin1String("QtProject"));
settings.beginGroup(QLatin1String("QtNetwork"));
settings.setValue(QLatin1String("DefaultNetworkConfiguration"), id);
settings.endGroup();
}
tcpServer = new QTcpServer(this);
if (!tcpServer->listen(QHostAddress::Any, Server::port)) {
return;
}
qDebug() << "Server listening on: " << tcpServer->serverPort();
//! [0]
QString ipAddress;
QList<QHostAddress> ipAddressesList = QNetworkInterface::allAddresses();
// use the first non-localhost IPv4 address
for (int i = 0; i < ipAddressesList.size(); ++i) {
if (ipAddressesList.at(i) != QHostAddress::LocalHost &&
ipAddressesList.at(i).toIPv4Address()) {
ipAddress = ipAddressesList.at(i).toString();
break;
}
}
// if we did not find one, use IPv4 localhost
if (ipAddress.isEmpty())
ipAddress = QHostAddress(QHostAddress::LocalHost).toString();
//! [1]
}
void Server::openNewConnection(void)
{
qDebug() << "New conn incoming!";
Server::clientConnection = tcpServer->nextPendingConnection();
QVariant ipAddr_QVar(clientConnection->peerAddress().toString());
qDebug() << "Got new connection!";
emit gotNewConnection(ipAddr_QVar);
}
The main problem here is that even if I get a "Connected" from
if (tcpSocket->waitForConnected(1000))
qDebug("Connected!");
qDebug() << "Am I connected" << tcpSocket->state();
in the client function, but the server function openNewConnection() never gets called. Why? How can I find the bug?
If a minimal working example is necessary, I can provide the whole code, but here I just wanted to provide the most important functions.
Edit:
client.h:
#ifndef CLIENT_H
#define CLIENT_H
//#include <QDialog>
#include <iostream>
#include <QTcpSocket>
class QComboBox;
class QDialogButtonBox;
class QLabel;
class QLineEdit;
class QPushButton;
class QTcpSocket;
class QNetworkSession;
class Client : public QObject
{
Q_OBJECT
private:
QTcpSocket *tcpSocket;
QString currentFortune;
quint16 blockSize;
QPair<QString, QPair<QString, QVariant> > data;
QNetworkSession *networkSession;
QString purpose;
signals:
void gotData(QPair<QString, QPair<QString, QVariant> >);
void noConnection(void);
void connectionResult(bool);
void isDisconnect(bool);
public slots:
void displayError(QAbstractSocket::SocketError socketError);
void sessionOpened();
void getInfo();
void readData();
void connectToServer(QString ipAddr, quint32 port);
void disconnectFromServer();
private:
public:
Client(QString purpose);
};
#endif // CLIENT_H
server.h:
#ifndef SERVER_H
#define SERVER_H
#include <QTcpServer>
#include <iostream>
//#include <QtTest/QTest>
#include <QSignalSpy>
#include <QTcpSocket>
#include <QDebug>
//#include <QMessageBox>
#include <QNetworkInterface>
#include <typeinfo>
#include <QStringList>
//#include <QSignalSpy>
QT_BEGIN_NAMESPACE
class QTcpServer;
class QNetworkSession;
QT_END_NAMESPACE
class Server : public QObject
{
Q_OBJECT
public slots:
void sessionOpened();
void sendFortune(void);
void sendData(QPair<QString, QPair<QString, QVariant> > data);
void sendFile(QVariant fileName);
void disconnectServer(void);
void openNewConnection(void);
signals:
void gotNewConnection(QVariant);
private:
QString purpose;
QTcpServer *tcpServer;
QString ipAddr;
quint32 port;
QTcpSocket *clientConnection;
quint32 BlockSize;
bool firstTime;
QSignalSpy * m_pSignalSpy;
QStringList fortunes;
QNetworkSession *networkSession;
//QNetworkConfiguration config;
public:
Server(QString ipAddr, quint32 port, QString purpose = "");
};
#endif // SERVER_H

Answer 1

The problem lies with your QNetworkSession, you have declared it in scope. Meaning once you leave that function the QNetworkSession gets destroyed. A destroyed object cannot emit a signal. Maybe make it a member variable or construct it in your header.