how to check computer's state using Qt?

Question

i'm trying to get computer's state in my LAN... thought about using QTcpSocket but it's not realy effective since port also should be inserted as:

socket->connectToHost("hostName", portNumber);
if (socket->waitForConnected(1000))
     qDebug("Connected!");

can anyone demonstare me a better way to check if computer is responding ?

Answer 1

One good way is just to verify that they can resolve domain names using QHostInfo. If they can then they likely have internet access:

QHostInfo::lookupHost("www.kde.org", this, SLOT(lookedUp(QHostInfo)));

Of course, you could just try to connect to the host as well, which is even better proof that everything is working correctly. I would do it asynchronously rather than synchronously, but it's truly the best test.

Answer 2

ping

int exitCode = QProcess::execute("ping", QStringList() << "-c1" << "hostname");
if (0 == exitCode) {
    // it's alive
} else {
    // it's dead
}

Arguments may vary. For example, I believe it would be ping -n 1 "hostname" on Windows. The example should work on most non-Windows versions.

Answer 3

Are you trying to check if your local machine is on the network or if a target machine is ?

There isn't a good cross platform way of doing this. The nearest on qt is QNetworkInterface, and check attribute "ISup" - it's not perfect, it may be active if you have a network cable connected but just to a router, and inactive if you have a 3G modem but aren't on a call.

On Windows check InternetGetConnectedState()