Monitoring internet connection status - qt

Question

How can I monitor internet connection status in qt? What I mean is that I'd like to be able to change icon to active/inactive depend on internet connection being present or not.

Answer 1

If you are using QML, there is NetworkInfo QML element from Qt Mobility package. Also, that contains an example, how to check is WLAN connection present.

Answer 2

I use this code to check the internet status.
bool ConnectivityManager::isOnline()
{
bool retVal = false;
QNetworkAccessManager nam;
QNetworkRequest req(QUrl("http://www.google.com"));
QNetworkReply* reply = nam.get(req);
QEventLoop loop;
QTimer timeoutTimer;
connect(&timeoutTimer, SIGNAL(timeout()), &loop, SLOT(quit()));
connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
timeoutTimer.setSingleShot(true);
timeoutTimer.start(3000);
loop.exec();
if (reply->bytesAvailable())
{
retVal = true;
}
return retVal;
}

Answer 3

I've had an issue using a solution similar to the Winston Rodrigues one and Flatpak. This solution was working on almost all computers I have tested but one. Internet connection was not detected for unclear reason (no error was raised). So, here is the solution that works for me in all situations, so far:
bool InternetIsOn()
{
QUrl host("1.1.1.1"); // put here URL (or IP) of your own website if you have one
qDebug() << tr("Checking internet connection: connecting to %1 ...").arg(host.toString());
QTcpSocket* sock = new QTcpSocket(this);
connect(sock, &QTcpSocket::errorOccurred, this, [](QAbstractSocket::SocketError error) {
qDebug() << "This error occured during Internet checking:" << error;
});
sock->connectToHost(host.toString(), 80);
bool connected = sock->waitForConnected(3'000);//ms
if (!connected)
{
sock->abort();
qDebug() << tr("%1 is not reachable. Not connected to the Internet").arg(host.toString());
return false;
}
sock->close();
qDebug() << tr("Connected to the Internet");
return true;
}