How to download files from SourceForge using Qt

Question

I'm writing a C++ application using Qt framework that needs to download a file from SourceForge.

I have to download this file https://sourceforge.net/projects/meshlab/files/updates/1.3.3/updates.xml

I wrote the following code using Qt and the QHttp class:

QFile tmpfile;
int hostreqid;
int checkreqid;
...
...
tmpfile.setFileName("updates.xml");
hostreqid = http.setHost("sourceforge.net",QHttp::ConnectionModeHttp);
checkreqid = http.get(QString(QUrl::toPercentEncoding("/projects/meshlab/files/updates/1.3.3/updates.xml")),&tmpfile);
...
...
void parseAnswer( int id,bool error )
{
    if (!error && (id == checkreqid))
    {
            ...
        tmpfile.close();
    }
    if (error)
    {
        QHttp::Error err = http.error();
        QString errstrg = http.errorString();
    }
}

Both QHttp::setHost and QHttp::get are not blocking functions returning immediately an int id. When the http file transfer completed the parseAnswer function is automatically called. The problem is that inside the updates.xml file I got, instead the data I was expecting I received an html file from SouceForge reporting an "Invalid Project" error.

I noticed that when I access the https://sourceforge.net/projects/meshlab/files/updates/1.3.3/updates.xml from browser I have been redirected to https://sourceforge.net/projects/meshlab/files/updates/1.3.3/updates.xml/download page. I tried also this other address but nothing changed.

Please, notice that I'm using Http protocol (QHttp::ConnectionModeHttp) instead of the https. If I could I would wish to avoid to use the https. Can be the source of the problem?

Thanks a lot!

Answer 1

I got the answer in another forum (thanks to AcerExtensa...I don't know his real name). Looks like the problem was that I missed to handle the sourceforge redirection. I posted here his reply:

#ifndef SFORGE_H
#define SFORGE_H

#include <QNetworkAccessManager>
#include <QNetworkReply>

class SForge : public QNetworkAccessManager
{
    Q_OBJECT
public:
    explicit SForge(QObject *parent = 0);


private slots:
    void fin(QNetworkReply *);

};

#endif // SFORGE_H
code:
#include "sforge.h"
#include <QDateTime>
#include <QUrl>
#include <QNetworkRequest>
#include <QDebug>

SForge::SForge(QObject *parent):QNetworkAccessManager(parent)
{
    QUrl url("http://downloads.sourceforge.net/project/meshlab/updates/1.3.3/updates.xml?r=&ts="+QString::number(QDateTime::currentDateTime().toTime_t())+"&use_mirror=heanet");

    connect(this, SIGNAL(finished(QNetworkReply*)), this, SLOT(fin(QNetworkReply*)));

    QNetworkRequest req(url);
    this->get(req);
}

void SForge::fin(QNetworkReply * reply)
{
    if(reply->error() != QNetworkReply::NoError)
        qDebug() << reply->errorString();

    if(reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt() == 307 || reply->rawHeaderList().contains("Location"))
    {
        QNetworkRequest req(reply->header(QNetworkRequest::LocationHeader).toString());
        this->get(req);
        return;
    }

    qDebug() << __LINE__ << reply->bytesAvailable() << reply->readAll();
}

Thanks a lot to the ones who tried to help me!