public PingResult ping(ScanningSubject subject, int count) throws IOException {
PingResult result = new PingResult(subject.getAddress());
DatagramSocket socket = sockets.bind(new DatagramSocket());
socket.setSoTimeout(timeout);
socket.connect(subject.getAddress(), PROBE_UDP_PORT);
for (int i = 0; i < count && !Thread.currentThread().isInterrupted(); i++) {
long startTime = System.currentTimeMillis();
byte[] payload = new byte[8];
ByteBuffer.wrap(payload).putLong(startTime);
DatagramPacket packet = new DatagramPacket(payload, payload.length);
try {
socket.send(packet);
socket.receive(packet);
} catch (PortUnreachableException e) {
result.addReply(System.currentTimeMillis() - startTime);
} catch (SocketTimeoutException ignore) {
} catch (NoRouteToHostException e) {
// this means that the host is down
break;
} catch (SocketException e) {
if (e.getMessage().contains(/*No*/ "route to host")) {
// sometimes 'No route to host' also gets here...
break;
}
} catch (IOException e) {
LOG.log(FINER, subject.toString(), e);
}
}
return result;
}
public void close() {
sockets.close();
}