Qt 6.4.2 and FTP Upload - Windows 11

[Juan de Dironne]

I am new to this Forum. I hope my question is well worded and in the right place.

I use this code to test ftp upload with "QNetworkAccessManager" functions.

main.cpp

#include <QApplication>
#include <QtWidgets>
#include "MyMainWindow.h"


int main (int nbArg, char* listArg[])
{
  QApplication myApp(nbArg,listArg);

  MyMainWindow myWindow;
  myWindow.show();

  myApp.exec();
}

MyMainWindow.h

#ifndef MYMAINWINDOW_H
#define MYMAINWINDOW_H

#include<QtWidgets>
#include<QUrl>
#include<QFile>
#include<QtNetwork/QNetworkAccessManager>
#include<QtNetwork/QNetworkReply>

class MyMainWindow : public QMainWindow
{
  Q_OBJECT

  public:
  MyMainWindow();

  public slots:
  void upload();
  void transfertFinished(QNetworkReply*);
  void displayError(QNetworkReply::NetworkError);

  private:
  QAction *m_actionUpload;
  QAction *m_actionQuit;

  private:
  QNetworkAccessManager *m_accesManager;
  QFile *m_fileTransfert;
  QNetworkReply *m_responseTransfert;
};

#endif // MYMAINWINDOW_H

MyMainWindow.cpp

#include "MyMainWindow.h"

MyMainWindow::MyMainWindow()
{
  m_accesManager = new QNetworkAccessManager(this);

  // Define Actions
  m_actionUpload  = new QAction("Upload",this);
  m_actionQuit    = new QAction("Quit",this);

  // Define Menu
  QMenu *fileMenu = menuBar()->addMenu("File");
  fileMenu->addAction(m_actionUpload);
  fileMenu->addAction(m_actionQuit);

  // Create Slot for Menu
  connect(m_actionUpload,SIGNAL(triggered()),this,SLOT(upload()));
  connect(m_actionQuit,SIGNAL(triggered()),qApp,SLOT(quit()));
}


void MyMainWindow::upload()
{
  // Initialization
  QString localFileName   = "local_file.txt";
  QString distantFileName = "distant_file.txt";
  QUrl myUrl;
  QByteArray fileContent;

  // FTP Parameters
  myUrl.setScheme("ftp");
  myUrl.setHost("myServer.fr");
  myUrl.setPort(21);
  myUrl.setUserName("myLogin");
  myUrl.setPassword("myPassword");
  myUrl.setPath(distantFileName);


  // File Object
  m_fileTransfert = new QFile(localFileName,this);

  // If File Exist
  if(m_fileTransfert->exists())
  {
    // Create Request "Object" (from "object" URL)
    QNetworkRequest myRequest(myUrl);

    // Open Local File
    m_fileTransfert->open(QIODevice::ReadOnly);
    fileContent = m_fileTransfert->readAll();

    // Send the File via the Request object
    m_responseTransfert = m_accesManager->put(myRequest,fileContent);
  }
  else qDebug() << "File No Exist";
}

When I test for the first time, I have this error "qt.tlsbackend.ossl: Failed to load libssl/libcrypto"

So I use "Qt Maintenance Tool" to install "OpenSSL 1.1.1q Toolkit".
I then copy the installed "libcrypto-1_1-x64.dll" and "libssl-1_1-x64.dll" files into my executable folder.
And testing the script again no more errors.
But so far no file deposited on my server.

And adding error handling with the code below

 // Send the File via the Request object
 m_responseTransfert = m_accesManager->put(myRequest,fileContent);

 // Slots
 connect(m_responseTransfert,SIGNAL(errorOccurred(QNetworkReply::NetworkError)),this,SLOT(displayError(QNetworkReply::NetworkError)));

and

void MyMainWindow::displayError(QNetworkReply::NetworkError errorFonc)
{
  qDebug() << "Error : " << errorFonc;
  qDebug() << m_responseTransfert->errorString();
}

I obtain this error message
Error : QNetworkReply::ProtocolUnknownError
"Protocol "ftp" is unknown"

What is wrong or missing in this code to get this error....?
And as specified in the title I am under Windows 11 (this information is important in my opinion)
And I am using "MSVC2019_64bit" compiler

[mrjj]

Hi
I have a feeling maybe its not included or something like that. code looks good.

What do you get if you do
qDebug() << m_accesManager->supportedSchemes();

[Cobra91151]

@Juan-de-Dironne

Hello!

It seems Qt 6 does not have FTP support in Qt Network because they moved it to some plugin. More details you can get here: https://www.qt.io/blog/qt-network-in-qt-6
Also, I recommend you to check out this Qt SCXML FTP Client Example: https://doc-snapshots.qt.io/qt6-dev/qtscxml-ftpclient-example.html using Qt 6. It could be useful for you.

[Juan de Dironne]

@mrjj Thank you for taking the time to look and respond to me. I tried your code to see what schemes were supported and... FTP is not include :(
So I must use QT 5 to do FTP...?

[Juan de Dironne]

@Cobra91151 I had seen this code before but I found this code complex.
So I searched for a code that seemed simpler to me and I came across this solution using "QNetworkAccessManager".
But it seems it doesn't work as you say with QT 6 :(

[Bonnie]

According to this post https://forum.qt.io/topic/136161/qt6-qnetworkrequest-and-ftp, they planned to move ftp support to plugin in Qt6 but never really done that because "little-to-no demand" and using libcurl is an alternative solution.

[Jonas Kvinge]

So I use "Qt Maintenance Tool" to install "OpenSSL 1.1.1q Toolkit".
I then copy the installed "libcrypto-1_1-x64.dll" and "libssl-1_1-x64.dll" files into my executable folder.

You need one of the TLS backends too, either qschannelbackend.dll or qopensslbackend.dll copied over to a directory called "tls". You only need libcrypto and libssl if you use the openssl backend instead of the schannel.

[Juan de Dironne]

@Jonas-Kvinge The problem was indeed not related to OpenSSL but to the version of QT.
With QT 5.15.2, the code allows to send the file to the Server.
With QT 6.4.2, the code returns an error "Protocol FTP is unknow".

But in which case I have to copy the TLS backends...? And the TLS directory you're talking about, where should it be...?

[sidthatsme]

@Juan-de-Dironne I had similar problems with FTP.
Qt 5 and FTP worked fine
With QT 6, I had to use ScXML to get my app to access FTP site.
It is possible but a lot of work is needed to get scxml to to access the FTP site of choosing