Trouble Applying the Fortune Threaded Server

[dhice]

I'm trying to integrate a QTcpServer into my program. My initial attempt was to use the Fortune client to connect to my server, and my server return a simple string. I'm not sure why, but the Fortune client will not connect.

I'm running both my program and the Fortune Client on my computer, using a connection address of Localhost and port 1000.

Here is my code:

Server.h

#ifndef SERVER_H
#define SERVER_H
#include <QTcpServer>
 class Server : public QTcpServer
 {
     Q_OBJECT
 
 public:
     Server(QObject *parent = 0);
 
 protected slots :
     void incomingConnection(int socketDescriptor);
 
 };
 
#endif // SERVER_H

#ifndef SERVER_H
#define SERVER_H
#include <QTcpServer>
 class Server : public QTcpServer
 {
     Q_OBJECT

 public:
     Server(QObject *parent = 0);

 protected slots :
     void incomingConnection(int socketDescriptor);

 };

#endif // SERVER_H

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Server.cpp

#include "Server.h"
#include "ServerThread.h"
#include <QDebug>
 
 
Server::Server(QObject *parent)
     : QTcpServer(parent)
 {
    connect(this, SIGNAL(newConnection()), this, SLOT(incommingConnection(socketDescriptor)));
 }
 
 void Server::incomingConnection(int socketDescriptor)
 {
     qDebug() << "Incomming!";
     QString fortune = "Test";
     ServerThread *thread = new simonServerThread(socketDescriptor, fortune, this);
     connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
     thread->start();
 }

#include "Server.h"
#include "ServerThread.h"
#include <QDebug>


Server::Server(QObject *parent)
     : QTcpServer(parent)
 {
    connect(this, SIGNAL(newConnection()), this, SLOT(incommingConnection(socketDescriptor)));
 }

 void Server::incomingConnection(int socketDescriptor)
 {
     qDebug() << "Incomming!";
     QString fortune = "Test";
     ServerThread *thread = new simonServerThread(socketDescriptor, fortune, this);
     connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
     thread->start();
 }

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ServerThread.h

#ifndef SERVERTHREAD_H
#define SERVERTHREAD_H
 
 #include <QThread>
 #include <QTcpSocket>
 
 class ServerThread : public QThread
 {
     Q_OBJECT
 
 public:
     ServerThread(int socketDescriptor, const QString &fortune, QObject *parent);
 
     void run();
 
 signals:
     void error(QTcpSocket::SocketError socketError);
 
 private:
     int socketDescriptor;
     QString text;
 };
 
 
#endif // SERVERTHREAD_H

#ifndef SERVERTHREAD_H
#define SERVERTHREAD_H

 #include <QThread>
 #include <QTcpSocket>

 class ServerThread : public QThread
 {
     Q_OBJECT

 public:
     ServerThread(int socketDescriptor, const QString &fortune, QObject *parent);

     void run();

 signals:
     void error(QTcpSocket::SocketError socketError);

 private:
     int socketDescriptor;
     QString text;
 };


#endif // SERVERTHREAD_H

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ServerThread.cpp

#include "ServerThread.h"
 
ServerThread::ServerThread(int socketDescriptor, const QString &fortune, QObject *parent)
     : QThread(parent), socketDescriptor(socketDescriptor), text(fortune)
 {
 }
 
 void ServerThread::run()
 {
     QTcpSocket tcpSocket;
     if (!tcpSocket.setSocketDescriptor(socketDescriptor)) {
         emit error(tcpSocket.error());
         return;
     }
 
     QByteArray block;
     QDataStream out(&block, QIODevice::WriteOnly);
     out.setVersion(QDataStream::Qt_4_0);
     out << (quint16)0;
     out << text;
     out.device()->seek(0);
     out << (quint16)(block.size() - sizeof(quint16));
 
     tcpSocket.write(block);
     tcpSocket.disconnectFromHost();
     tcpSocket.waitForDisconnected();
 }

#include "ServerThread.h"

ServerThread::ServerThread(int socketDescriptor, const QString &fortune, QObject *parent)
     : QThread(parent), socketDescriptor(socketDescriptor), text(fortune)
 {
 }

 void ServerThread::run()
 {
     QTcpSocket tcpSocket;
     if (!tcpSocket.setSocketDescriptor(socketDescriptor)) {
         emit error(tcpSocket.error());
         return;
     }

     QByteArray block;
     QDataStream out(&block, QIODevice::WriteOnly);
     out.setVersion(QDataStream::Qt_4_0);
     out << (quint16)0;
     out << text;
     out.device()->seek(0);
     out << (quint16)(block.size() - sizeof(quint16));

     tcpSocket.write(block);
     tcpSocket.disconnectFromHost();
     tcpSocket.waitForDisconnected();
 }

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I'm calling the server using the following:

Server server;
       if (!server.listen(QHostAddress::Any, 1000)) {
            QMessageBox::critical(this, tr("Threaded Fortune Server"),
                               tr("Unable to start the server: %1.")
                               .arg(server.errorString()));
            server.close();
       }

Server server;
       if (!server.listen(QHostAddress::Any, 1000)) {
            QMessageBox::critical(this, tr("Threaded Fortune Server"),
                               tr("Unable to start the server: %1.")
                               .arg(server.errorString()));
            server.close();
       }

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Thanks for trying to help!

[wysota]

Did you start the event loop in the main thread?

[dhice]

Yes the GUI event loop has been started.

[wysota]

Try connecting to the server with a telnet client and see if you can connect at all. And also try a higher port - ones between 1 and 1024 are reserved for well-known services and (may) require superuser privileges.

[dhice]

I changed the port number to 5000 with out any luck.

I then attempted telneting using this command

telnet localhost 5000

telnet localhost 5000

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And it couldn't connect. The connection will go through if I omit the port number, so the telnet service is on.

[wysota]

What exactly message did you get when trying to connect to the port using telnet? "Connection refused" or something like "Connection closed by remote host"?

[dhice]

OK, I have the server working correctly now, as I can send/receive data between the server embedded in my program to a small client I created for testing purposes. Now I'm having trouble getting readyRead() to emit on the client side.

I modeled the embedded client code after the small client I made directly.

Here is my updated code.

client.h

#ifndef CLIENT_H
#define CLIENT_H
#include <QtGui/QDialog>
#include <QtNetwork>
#include <QVector>
 
 
class client : public QObject
{
    Q_OBJECT
 
public:
    client();
    ~client();
    QString      hostname;
    QVector<int> sequence;
    int state;
    int ready;
    void requestData();
    QTcpSocket* socket;
    void readData();
 
private:
 
 
private slots:
 
    void readyReadTest();
 
signals:
    void dataComplete();
};
 
#endif // CLIENT_H

#ifndef CLIENT_H
#define CLIENT_H
#include <QtGui/QDialog>
#include <QtNetwork>
#include <QVector>


class client : public QObject
{
    Q_OBJECT

public:
    client();
    ~client();
    QString      hostname;
    QVector<int> sequence;
    int state;
    int ready;
    void requestData();
    QTcpSocket* socket;
    void readData();

private:


private slots:

    void readyReadTest();

signals:
    void dataComplete();
};

#endif // CLIENT_H

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client.cpp

#include "client.h"
#include <QDebug>
 
client::client()
{
    qDebug() << "CLIENT>> \"Client Initialized\"";
    ready = 0;
}
 
client::~client()
{
 
}
 
 
void client::requestData(){
 
    socket = new QTcpSocket(this);
    connect(socket, SIGNAL(readyRead()), this, SLOT(readyReadTest()));
    connect(socket, SIGNAL(readyRead()), this, SLOT(readData()));
    connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
    qDebug() << "CLIENT>> CONNECTING TO  \"" << hostname << ":5000\"";
    QHostAddress address;
    address.setAddress(hostname);
    socket->connectToHost(address, 5000);
    if(socket->isValid()){
        qDebug() << "CLIENT>> CONNECTED TO: \""<<hostname << ":5000\"";
    }
    else{
        qDebug() << "CLIENT>> FAILED TO CONNECTED TO: \""<<hostname << ":5000\"";
    }
}
 
void client::readData(){
    qDebug() << "CLIENT>> ATTEMPTING TO RECEIVE DATA";
    int z = sequence.size();
    sequence.clear();
    QDataStream in(socket);
    in.setVersion(QDataStream::Qt_4_1);
    QString msg;
    in >> msg;
    qDebug() << "CLIENT>> MSG " << msg;
    if(msg == ""){
          qDebug() << "CLIENT>> MSG WAS NOT RECEIVED";
    }
    else{
          qDebug() << "CLIENT>> MSG RECEIVED";
    }
    delete socket;
    emit dataComplete();
}
 
void client::readyReadTest(){
    qDebug() << "CLIENT>> READYREAD WAS EMITTED";
}

#include "client.h"
#include <QDebug>

client::client()
{
    qDebug() << "CLIENT>> \"Client Initialized\"";
    ready = 0;
}

client::~client()
{

}


void client::requestData(){

    socket = new QTcpSocket(this);
    connect(socket, SIGNAL(readyRead()), this, SLOT(readyReadTest()));
    connect(socket, SIGNAL(readyRead()), this, SLOT(readData()));
    connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
    qDebug() << "CLIENT>> CONNECTING TO  \"" << hostname << ":5000\"";
    QHostAddress address;
    address.setAddress(hostname);
    socket->connectToHost(address, 5000);
    if(socket->isValid()){
        qDebug() << "CLIENT>> CONNECTED TO: \""<<hostname << ":5000\"";
    }
    else{
        qDebug() << "CLIENT>> FAILED TO CONNECTED TO: \""<<hostname << ":5000\"";
    }
}

void client::readData(){
    qDebug() << "CLIENT>> ATTEMPTING TO RECEIVE DATA";
    int z = sequence.size();
    sequence.clear();
    QDataStream in(socket);
    in.setVersion(QDataStream::Qt_4_1);
    QString msg;
    in >> msg;
    qDebug() << "CLIENT>> MSG " << msg;
    if(msg == ""){
          qDebug() << "CLIENT>> MSG WAS NOT RECEIVED";
    }
    else{
          qDebug() << "CLIENT>> MSG RECEIVED";
    }
    delete socket;
    emit dataComplete();
}

void client::readyReadTest(){
    qDebug() << "CLIENT>> READYREAD WAS EMITTED";
}

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server.h

#ifndef SERVER_H
#define SERVER_H
 
#include <QtNetwork>
 
class server : public QTcpServer{
    Q_OBJECT
    public:
        server(QObject* parent = 0);
        QVector<int> *sequence;
        int checkIn;
        int state;
 
    protected slots:
        void sendMessage();
        void connectCheck();
};
 
#endif // SERVER_H

#ifndef SERVER_H
#define SERVER_H

#include <QtNetwork>

class server : public QTcpServer{
    Q_OBJECT
    public:
        server(QObject* parent = 0);
        QVector<int> *sequence;
        int checkIn;
        int state;

    protected slots:
        void sendMessage();
        void connectCheck();
};

#endif // SERVER_H

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server.cpp

#include "server.h"
#include <QDebug>
 
server::server(QObject* parent) : QTcpServer(parent) {
    qDebug() << "SERVER>> \"Server Intialized\"";
    connect(this, SIGNAL(newConnection()), this, SLOT(sendMessage()));
}
 
void server::sendMessage(){
    qDebug() << "SERVER>> PREPARING TO SEND DATA";
    QString message;
    QTcpSocket* client = this->nextPendingConnection();
    QByteArray block;
    QDataStream outgoingMessage(&block, QIODevice::WriteOnly);
    outgoingMessage.setVersion(QDataStream::Qt_4_1);
    int i = 0;
    qDebug() << "SERVER>> SEQUENCE SIZE " << (*sequence).size();
    for(i; i < (*sequence).size();i++){
        message = QString::number((*sequence)[i]);
        qDebug() << "SERVER>> SENDING\"" << message << "\"";
        outgoingMessage << message;
    }
    client->write(block);
    client->disconnectFromHost();
}

#include "server.h"
#include <QDebug>

server::server(QObject* parent) : QTcpServer(parent) {
    qDebug() << "SERVER>> \"Server Intialized\"";
    connect(this, SIGNAL(newConnection()), this, SLOT(sendMessage()));
}

void server::sendMessage(){
    qDebug() << "SERVER>> PREPARING TO SEND DATA";
    QString message;
    QTcpSocket* client = this->nextPendingConnection();
    QByteArray block;
    QDataStream outgoingMessage(&block, QIODevice::WriteOnly);
    outgoingMessage.setVersion(QDataStream::Qt_4_1);
    int i = 0;
    qDebug() << "SERVER>> SEQUENCE SIZE " << (*sequence).size();
    for(i; i < (*sequence).size();i++){
        message = QString::number((*sequence)[i]);
        qDebug() << "SERVER>> SENDING\"" << message << "\"";
        outgoingMessage << message;
    }
    client->write(block);
    client->disconnectFromHost();
}

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How I'm calling the server/client

if(player == 1){
            qDebug() << "ENGINE>> GENERATING NEXT NUMBER";
            generate_number();
            SERVER->sequence = &sequence_computer;
        }
        else{
            client CLIENT;
            CLIENT.hostname = hostname;
            while(sequence_computer.size() == 0){
                CLIENT.requestData();
                sequence_computer = CLIENT.sequence;
                qDebug() << "ENGINE>> WAITING FOR CLIENT TO RECEIVE SEQUENCE";
                msleep(1000);
            }
        }

if(player == 1){
            qDebug() << "ENGINE>> GENERATING NEXT NUMBER";
            generate_number();
            SERVER->sequence = &sequence_computer;
        }
        else{
            client CLIENT;
            CLIENT.hostname = hostname;
            while(sequence_computer.size() == 0){
                CLIENT.requestData();
                sequence_computer = CLIENT.sequence;
                qDebug() << "ENGINE>> WAITING FOR CLIENT TO RECEIVE SEQUENCE";
                msleep(1000);
            }
        }

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I do have a few unused variables in the header files (debugging and haven't removed them yet)

Thanks for any help to understand why readyRead() isn't firing.

[wysota]

Because there is nothing written to the socket. You are disconnecting the server from the client before the data has a chance to be written. You need to wait for bytesWritten before calling disconnectFromHost.