Issue with FTP using QNetworkAccessManager

[CLBSII]

Hi evereyone,

I want to use QNetworkAccessManager in order to download a file from a FTP server. Basicly, I use the following code according to the documentation:

myNetworkManager = new QNetworkAccessManager(this);
QUrl url("ftp://FTP_server:1234@192.168.1.62:2121/file_1.png");
myNetworkRequest.setUrl(url);
myNetworkReply = myNetworkManager->get(myNetworkRequest);

It gives me this error:

qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No functional TLS backend was found
qt.network.ssl: No TLS backend is available

After some research, it appears the openSSL library is not include in QT. I found a bunch of tutorial explaining how to install it, but it not seems so easy.

So is this the only solution, or do I do something wrong using QNetworkAccessManager for my FTP request ?

Thanks all.

[SGaist]

Yes, it's one way to implement it.

[raven-worx]

@CLBSII
what type of FTP server is this?
normally FTP is unencrypted. But FTP over SSL first connects via FTP and then switches to a secure encrypted port.

Installation of OpenSSL libs is actually pretty easy.
Simply copy the 2 OpenSSL libs either next to your executable or ensure that they are in the PATH env variable (assuming you are on Windows)
https://wiki.openssl.org/index.php/Binaries
or install it via the Qt MaintenanceTool

What Qt version btw?

[CLBSII]

@raven-worx
To be honest, my FTP server is running on a distant computer using this Python Library, so I'm not sure for the type.

Well it seems you was right, I successfully installed the OpenSSL lib following your link and the error disappeared. Thanks for helping (and yes I'm on Windows).

However, my code doesn't seems to work. I mean, there are no errors, bu the file is not downloaded and the FTP server doesn't receive any notifications.

I spent my all day searching for a good example, but all I could get was this code. I also know I need to do something like this after:

    m_file.setFileName("file_1.png");
    m_file.open(QIODevice::WriteOnly | QIODevice::Append);
    m_file.write(myNetworkReply->readAll());

But it doesn't change anything. No files created. Seems like the myNetworkReply var is empty.

[raven-worx]

@CLBSII
when exactly do you execute this code?

[CLBSII]

@raven-worx
During the initialization of my application. I call function that doing all those things:

void MyApp::DownloadFtp()
{
   myNetworkManager = new QNetworkAccessManager(this);
   QUrl url("ftp://Vprint_FTP:1234@192.168.1.62:2121/file_1.png");
   qDebug()<<url;
   myNetworkRequest.setUrl(url);
   myNetworkReply = myNetworkManager->get(myNetworkRequest);

   m_file.setFileName("file_1.png");
   m_file.open(QIODevice::WriteOnly | QIODevice::Append);
   m_file.write(myNetworkReply->readAll());
}

I don't know if it answer to your question ?
One thing that bother me is that the qDebug line returns me :

QUrl("sftp://Vprint_FTP@192.168.1.62:2121/1.png")

It is the same line that I set, without the password. Is it normal ?

[raven-worx]

@CLBSII
this way the request probably wasnt event sent yet.
you must connect to the finished signal of the reply and then read the data (and error checking of course)

[CLBSII]

@raven-worx
I'm not sure to understand. Do you mean I have to add some temporisation at some point ?

[SGaist]

Hi and welcome to devnet,

No, QNAM is an asynchronous class, you need to use signal and slots to implement your data processing once the answer fully arrived.

[CLBSII]

Thanks for your time.

I found this example. Is it relevant with what you explained to me ?

[SGaist]

Yes, it's one way to implement it.