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

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 2

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 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()