FTPClient using QTcpSocket and signals and slots



  • Hi everybody, I'm writing a FTP client application. This is the logic of the first project, where I stuck:

    1. The network communication is based on QTcpSocket - I made one class responsible for making a command-transmision socket. In the class socketconnection was one public function named test() responsible starting the communication. In this function was also a signal_and_slot_connection: connect(socket, SIGNAL(connected()), this, SLOT(connected())); Then the class socketconnection had a private function connected() that made the whole communication. I send from there every FTP command, etc... So i was able to send messages to the ftp server and getting answers and it works fine, this way I recieved a directory listing from the server (command LIST) - for this I must made a data-transfer socket. I works.

    And here comes the problem, because I'm clicking on one button in my application ("Connect"), the necessary connecting information was in some line edits but that works fine. The problem is, that now i need to transfer files. I got two buttons in the mainwindow. ("Download" and "Store") and I have no ide how get from this buttons acces to the command-transfer socket.

    I decided to change my project and make it better (logically)
    Changes i wanna make:
    -After clicking Connect-button (from mainwindow) the connection should be made (via command-transmision socket)
    -Next a method responsible for the directory listing should be defined (she must have access to the command-transmision socket) i this step i data-transmision socket should be also created for the directory listing.
    -After clicking the "Download" or "STORE" button the file transfer is starting. (Like the directory listing i think)

    Where is the problem? I Can't make the right communication between the ui components and the socketconnection class. I have no idea how get access to the UI:MainWindow *ui object and use it as a SIGNAL object.

    THANKS A LOT for every help from you guys.
    P.S. Sorry for my bad english :(


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Without seeing your code, it's pretty much crystal ball debugging. Can you share it ?

    Out of curiosity, are you tied to QTcpSocket ?



  • Hi, thank you for the reply:) Infortunately I can use only QTcpSocket for this project :/ It's the requirement to pass the course ony my studies.

    Here come's my source code and a screenshot from the project so you can see what files I have.
    !http://przeklej.org/file/vlK2gP/snapshot1.png(QTCreator-snapshot)!

    MAINWINDOW.h:
    @#ifndef MAINWINDOW_H
    #define MAINWINDOW_H

    #include <QMainWindow>
    #include <exitdialog.h>
    #include <QString>
    #include <QDirModel>

    namespace Ui {
    class MainWindow;
    }

    class MainWindow : public QMainWindow
    {
    Q_OBJECT

    public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void Refresh();
    QString url, login, password, port;
    private slots:
    void on_actionZako_cz_triggered();

    void on_actionKonfiguruj_triggered();
    
    void on_pushButton_clicked();
    
    void on_pushButton_3_clicked();
    
    void on_pushButton_2_clicked();
    
    void on_pushButton_5_clicked();
    

    private:
    QDirModel dirModel;
    Ui::MainWindow *ui;
    void addRoot(QString name, QString size, QString type);
    };

    #endif // MAINWINDOW_H
    @



  • MAINWINDOW.cpp
    @#include "mainwindow.h"
    #include "ui_mainwindow.h"
    #include "exitdialog.h"
    #include "konfigurujdialog.h"
    #include "socketconnection.h"
    #include <QMessageBox>
    #include <stdio.h>
    #include <QRegExp>

    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {
    ui->setupUi(this);
    Refresh();
    }

    MainWindow::~MainWindow()
    {
    delete ui;
    }

    void MainWindow::on_actionZako_cz_triggered()
    {
    ExitDialog *exit = new ExitDialog();
    exit->setModal(true);
    exit->exec();
    }

    void MainWindow::on_actionKonfiguruj_triggered()
    {
    KonfigurujDialog *konfig = new KonfigurujDialog();
    konfig->setModal(true);
    konfig->exec();
    }

    void MainWindow::on_pushButton_clicked() //connect button
    {
    ui->textBrowser->clear();
    ui->treeWidget_2->clear();
    url = ui->urlValue->text();
    login = ui->loginValue->text();
    password = ui->passwordValue->text();
    port = ui->portValue->text();

    socketconnection *s = new socketconnection(url, login, password, port);
    QString komunikat, komunikat2;
    QString* listaFolderow;
    QString* sciezkaFolderow;
    komunikat = s->test();                 
    listaFolderow = &(s->directoryList);   // downloading the content from the public variable that's carreing the dirlisting
    sciezkaFolderow = &(s->currentPath);   // downloading the content from the public variable that's carreing the currentpath on the ftp server
    ui->textBrowser->insertPlainText(komunikat);
    
    
    QRegExp regex1("\n");
    QRegExp regex2("[ ]+|\n");
                                
    std::string DirPath = sciezkaFolderow->toStdString();
    *sciezkaFolderow = "";
    for(int i = 0; i < DirPath.length(); i++)
    {
        int j = i+1;
        if(DirPath[i] == '\"')
        {
            while(DirPath[j] != '\"')
            {
                *sciezkaFolderow += DirPath[j];
                j++;
            }
            break;
        }
    }
    qDebug() << *sciezkaFolderow;
    
    ui->lineEdit_6->setText(*sciezkaFolderow);
    
    QStringList listing;                    //  lista zawierająca całe wiersze listingu plików
    listing = listaFolderow->split(regex1);
    
    std::string part;
    std::string partI, partII;
    QStringList QpartI;
    
    int i = 0, globalCounter = 0;
    foreach (QString var, listing)
        globalCounter++;
    QString czyFolder[globalCounter], Rozmiar[globalCounter], Nazwa[globalCounter];
    
    foreach (QString var, listing)
    {
       part = var.toStdString();
       int licznik = 0;
       for(int j = 0; j < part.length(); j++)
       {
           if(licznik < 55)
               partI += part[j];
           else
           {
               if(licznik == part.length()-1)
                   break;
               partII += part[j];
           }
           licznik++;
       }
    
       QpartI << QString::fromStdString(partI).split(regex2);
       Nazwa[i] = QString::fromStdString(partII);
       partI = "";
       partII = "";
       i++;
    }
    QpartI.removeAll("");
    i = 0;
    int j = 0;
    foreach(QString var, QpartI)
    {
        i++;
        if(i == 1)
        {
            if(var.left(1) == "d")
                czyFolder[j] = "Directory";
            else
                czyFolder[j] = "File";
        }
        if(i == 5)
            Rozmiar[j] = var;
    
        if(i == 8)
        {
            i = 0;
            j++;
        }
    }
    for(i = 0; i < globalCounter; i++)
    {
        addRoot(Nazwa[i], Rozmiar[i], czyFolder[i]);
    }
    

    }

    void MainWindow::addRoot(QString name, QString size, QString type)
    {
    QTreeWidgetItem pWidgetItem = new QTreeWidgetItem(ui->treeWidget_2);
    pWidgetItem->setText(0, name);
    pWidgetItem->setText(1, size);
    pWidgetItem->setText(2, type);
    ui->treeWidget_2->addTopLevelItem(pWidgetItem);
    }
    void MainWindow::Refresh()
    {
    dirModel.setParent(this);
    dirModel.setReadOnly(false);
    QDirModel
    model = &dirModel;
    ui->treeView->setModel(model);

    model->setSorting(QDir::DirsFirst | QDir::IgnoreCase | QDir::Name);
    
    QModelIndex index = model->index("/");
    ui->treeView->expand(index);
    ui->treeView->scrollTo(index);
    ui->treeView->setCurrentIndex(index);
    ui->treeView->resizeColumnToContents(0);
    
    // geting the filepath
    
    QFileInfo informacja;
    index = ui->treeView->currentIndex();
    informacja = model->fileInfo(index);
    ui->lineEdit->setText(informacja.filePath());
    

    }

    void MainWindow::on_pushButton_3_clicked() //button do przodu sekcji KOMPUTER LOKALNY
    {
    QDirModel* model = &dirModel;
    QModelIndex index = ui->treeView->currentIndex();
    ui->treeView->expand(index);
    QFileInfo informacja = model->fileInfo(index);
    ui->lineEdit->setText(informacja.filePath());
    index = ui->treeView->indexBelow(ui->treeView->currentIndex());

    ui->treeView->setCurrentIndex(index);
    

    }

    void MainWindow::on_pushButton_2_clicked() //button cofnij sekcji KOMPUTER LOKALNY
    {
    QDirModel* model = &dirModel;
    ui->treeView->collapse(ui->treeView->currentIndex());
    QModelIndex index = ui->treeView->indexAbove(ui->treeView->currentIndex());
    // QModelIndex index = ui->treeView->indexAbove(ui->treeView->currentIndex());

    ui->treeView->setCurrentIndex(index);
    QFileInfo informacja = model->fileInfo(index);
    ui->lineEdit->setText(informacja.filePath());
    

    }

    void MainWindow::on_pushButton_5_clicked() //butto do przodu sekcji SERWER
    {

    }
    @



  • SOCKETCONNECTION.h
    @#ifndef SOCKETCONNECTION_H
    #define SOCKETCONNECTION_H

    #include <QMainWindow>
    #include <QObject>
    #include <iostream>
    #include <QTcpSocket>
    #include <QAbstractSocket>
    #include <QString>

    class socketconnection : public QObject
    {
    Q_OBJECT
    public:
    explicit socketconnection(QString url, QString login, QString password, QString port, QObject *parent = 0);
    QString test();
    QString komunikat, message, command;
    QString url, login, password, port;
    QString directoryList; //pointer to the downloaded directory listing
    QString currentPath;
    signals:

    public slots:
    void connected();
    private:
    QTcpSocket *socket;
    QTcpSocket socketTransmit;
    };

    #endif // SOCKETCONNECTION_H
    @



  • SOCKETCONNECTION.cpp
    @#include "socketconnection.h"
    #include "mainwindow.h"
    #include <stdio.h>
    socketconnection::socketconnection(QString url, QString login, QString password, QString port, QObject *parent) :
    QObject(parent)
    {
    this->url = url;
    this->login = login;
    this->password = password;
    this->port = port;
    }
    QString socketconnection::test(){
    komunikat = "Status: ";
    socket = new QTcpSocket(this);
    connect(socket, SIGNAL(connected()), this, SLOT(connected()));
    komunikat += "Łączenie do serwera FTP...\n";
    socket->connectToHost((url.toUtf8().constData()), port.toShort());
    if(!socket->waitForConnected(3000)){
    komunikat += "Message: ";
    komunikat += "Przekroczony limit czasu...\n";
    }
    return komunikat;
    }
    void socketconnection::connected()
    {
    QString adresIP, transfer_port;
    std::string passive_connection = "";
    std::string oktet[6];
    int licznik = 0, portA, portB, portC;
    komunikat += "Message: ";
    while(message.length() == 0) message = socket->readLine();
    komunikat += message;
    komunikat += "Polecenie: ";
    message = "";
    command = "USER " + login + "\r\n";
    komunikat += "Polecenie: ";
    komunikat += command;
    socket->write(command.toUtf8().constData());
    socket->waitForBytesWritten(5000);
    while(message.length() == 0) message = socket->readLine();
    komunikat += "Message: ";
    komunikat += message;
    message = "";
    command = "PASS " + password + "\r\n";
    komunikat += "Polecenie: PASS <nie pokażę Ci hasła>\n";
    socket->write(command.toUtf8().constData());
    socket->waitForBytesWritten(5000);
    while(message.length() == 0) message = socket->readLine();
    komunikat += "Message: ";
    komunikat += message;
    message = "";
    command = "OPTS UTF8 ON\r\n";
    komunikat += "Polecenie: ";
    komunikat += command;
    socket->write(command.toUtf8().constData());
    socket->waitForBytesWritten(5000);
    while(message.length() == 0) message = socket->readLine();
    komunikat += "Message: ";
    komunikat += message;
    message = "";
    komunikat += "Status: Connected succesfully. Now I'm checking the directory list...\n";
    command = "TYPE I\r\n";
    komunikat += "Polecenie: ";
    komunikat += command;
    socket->write(command.toUtf8().constData());
    socket->waitForBytesWritten(5000);
    while(message.length() == 0) message = socket->readLine();
    komunikat += "Message: ";
    komunikat += message;
    message = "";
    command = "PWD \r\n";
    komunikat += "Polecenie: ";
    komunikat += command;
    socket->write(command.toUtf8().constData());
    socket->waitForBytesWritten(5000);
    int i = 0;
    while(message.length() == 0){
    message = socket->readLine();
    }
    currentPath = message;
    komunikat += "Message: ";
    komunikat += message;
    message = "";
    command = "PASV \r\n";
    komunikat += "Polecenie: ";
    komunikat += command;
    socket->write(command.toUtf8().constData());
    socket->waitForBytesWritten(5000);
    while(message.length() == 0) message = socket->readLine();
    komunikat += "Message: ";
    komunikat += message;
    passive_connection = message.toUtf8().constData();
    message = "";
    for(int i = 3; i < passive_connection.length()-2; i++){
    if(passive_connection[i] >= '0' && passive_connection[i] <= '9'){
    oktet[licznik] += passive_connection[i];
    if(passive_connection[i+1] == ',')
    {
    licznik++;
    continue;
    }
    }
    }
    adresIP = QString::fromStdString(oktet[0]) + "." + QString::fromStdString(oktet[1]) + "." + QString::fromStdString(oktet[2])
    + "." + QString::fromStdString(oktet[3]);
    portA = QString::fromStdString(oktet[4]).toInt();
    portB = QString::fromStdString(oktet[5]).toInt();
    portC = (portA * 256 + portB);
    transfer_port.setNum(portC);
    komunikat += "Tworzę połączenie na następujący adres i port: \n";
    komunikat += "Adres: " + adresIP + "\n";
    komunikat += "Port: " + transfer_port + "\n";

        socketTransmit.connectToHost(adresIP, portC);
        socketTransmit.waitForConnected(2000);
        komunikat += "Polecenie: ";
        command = "LIST \r\n";
        komunikat += command;
        socket->write(command.toUtf8().constData());
        socket->waitForBytesWritten(5000);              
        socketTransmit.waitForBytesWritten(5000);
        socketTransmit.waitForReadyRead(5000);
        socket->waitForBytesWritten(5000);
    
        socket->waitForBytesWritten(5000);
        message = socket->readLine();  //czekamy na odpowiedź kolejną z socketu poleceń
        komunikat += "Message: ";
        komunikat += message;
        message = "";
    
        message = socketTransmit.readAll();
        directoryList = message;    //  pobieramy do zmiennej directoryList listing plików i folderów
        if (directoryList != ""){
            komunikat += "Listing plików i folderów przesłąny z powodzeniem!!!:\n";
        }
        else
            komunikat += "Błąd! Nie udało mi się pobrać listy plików i folderów!!!\n";
        //komunikat += message;
        message = "";
        i = 0;
        while(message.length() == 0){
            i++;
            message = socket->readLine();
            if(i == 32768)
            {
                message = "Błąd podczas transmisji polecenia";
                break;
            }
        }
        komunikat += "Message: ";
        komunikat += message;
        message = "";
    }
    

    @



  • I know my code isn't nice but I've just started my QT experience, so I hope that you'll understand and can help me. Thanks a lot :)


  • Lifetime Qt Champion

    There are indeed several things that I don't follow:

    • Why are you mixing std::string and QString ? Currently it just complicates your code without any benefits
    • Why are you using pointers to QString ?

    You are also creating memory leaks with your custom dialogs.

    Anyway, for your original problem. You are doing everything in the connected slot, which is a bad idea. You need to refactor that and split the logic for the various commands you want to send in their own functions



  • I'm mixing QString with std::string because I couldn't filter the QString like a simple array, so I decided to go on the easiest way and parse it to std::string.

    I need pointers to QString because I have no idea how get access to one variable from one class in another class. I think pointers are a good method to get the content from variables....

    Which custom dialogs do you mean? I thinked about your advice to split to signal and slot system but I have trouble with it..... now i have something like that:
    @#include "mainwindow.h"
    #include "ui_mainwindow.h"

    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {
    ui->setupUi(this);
    }

    MainWindow::~MainWindow()
    {
    delete ui;
    }

    void MainWindow::on_pushButton_clicked() // connect Button
    {
    commandSocket = new QTcpSocket(this);

    login = ui->loginValue->text();
    url = ui->urlValue->text();
    password = ui->passwordValue->text();
    port = ui->portValue->text();
    qint64 timeout = 4000;
    
    connect(commandSocket, SIGNAL(connected()), this, SLOT(connected()));
    connect(commandSocket, SIGNAL(bytesWritten(timeout)), this, SLOT(getMessage()));
    qDebug() << "Connecting...";
    
    commandSocket->connectToHost(url, port.toShort());
    if(!commandSocket->waitForConnected(3000)){
        qDebug() << "Przekroczony limit czasu...\n";
    }
    

    }

    void MainWindow::connected()
    {
    qDebug() << "In connected()...";
    sendMessage("USER ", login);

    }
    void MainWindow::sendMessage(QString message, QString argument)
    {
    qDebug() << "in sendMessage...";
    QString displayedArgument, command;
    if(message == "PASS ")
    displayedArgument = "SECRET_PASSWORD...";
    else
    displayedArgument = argument;
    command = message + argument + "\r\n";
    commandSocket->write(command.toUtf8().constData());
    commandSocket->waitForBytesWritten(10000);

    ui->textBrowser->setOverwriteMode(false);
    ui->textBrowser->setText("Polecenie: " + message + displayedArgument + "\n");
    qDebug() << "send message done...";
    

    }
    void MainWindow::getMessage()
    {
    qDebug() << "In getMessage()...";
    QString message = "";
    //while(message == "")
    message = commandSocket->readLine();

    qDebug() << message;
    ui->textBrowser->setOverwriteMode(false);
    ui->textBrowser->setText(message);
    

    }@
    and unfortunately it's not working:/
    PS. I decidet to put everything in the mainwindow.cpp.


  • Lifetime Qt Champion

    What do you mean by "can't filter like a simple array" ?

    You should have a look at the fortune client/server example for inspiration



  • I mean something like that:
    @
    QString someQString = "I like Qt!", outputQString = "";
    for(int i = 0; i < someQString.length(); i++)
    {
    if(someQString[i] != " ")
    outputString += someQString[i];
    }
    @


  • Lifetime Qt Champion

    You want to remove all white spaces in the string ?
    From the top of my head:
    @
    someQString.replace(QRegular[removed]"\s"), "");
    @

    Replace QRegularExpression by QRegExp if you are on Qt 4



  • Thanks:) I moved forward with my project and now i need help with downloading files. The problem is that, when I download a file (first .txt) the data go on the socket but not everything. When i download a small file it works fine, but when I download a bigger file it looses data. :/ Do you have a advice form me?

    P.S. I start the download from the transfer socket, when on the commandLineSocket is the command RETR succesfully transmited.


  • Lifetime Qt Champion

    Look at readyRead and the asynchronousness handling of IO devices


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