/** * Initializes and binds a socket that on a random port number. The method would try to bind on a * random port and retry 5 times until a free port is found. * * @return the socket that we have initialized on a randomport number. */ private DatagramSocket initRandomPortSocket() { DatagramSocket resultSocket = null; String bindRetriesStr = NetaddrActivator.getConfigurationService().getString(BIND_RETRIES_PROPERTY_NAME); int bindRetries = 5; if (bindRetriesStr != null) { try { bindRetries = Integer.parseInt(bindRetriesStr); } catch (NumberFormatException ex) { logger.error( bindRetriesStr + " does not appear to be an integer. " + "Defaulting port bind retries to " + bindRetries, ex); } } int currentlyTriedPort = NetworkUtils.getRandomPortNumber(); // we'll first try to bind to a random port. if this fails we'll try // again (bindRetries times in all) until we find a free local port. for (int i = 0; i < bindRetries; i++) { try { resultSocket = new DatagramSocket(currentlyTriedPort); // we succeeded - break so that we don't try to bind again break; } catch (SocketException exc) { if (exc.getMessage().indexOf("Address already in use") == -1) { logger.fatal( "An exception occurred while trying to create" + "a local host discovery socket.", exc); resultSocket = null; return null; } // port seems to be taken. try another one. logger.debug("Port " + currentlyTriedPort + " seems in use."); currentlyTriedPort = NetworkUtils.getRandomPortNumber(); logger.debug("Retrying bind on port " + currentlyTriedPort); } } return resultSocket; }