/**
* Creates an unmodifiable local IP address set.
*
* @return an unmodifiable local IP address set.
*/
private static Set<InetAddress> createLocalInetAddresses() {
final Set<InetAddress> result = new HashSet<InetAddress>(11);
try {
final Enumeration<NetworkInterface> enumeration = NetworkInterface.getNetworkInterfaces();
while (enumeration.hasMoreElements()) {
final NetworkInterface networkInterface = enumeration.nextElement();
final Enumeration<InetAddress> inetAddresses = networkInterface.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
result.add(inetAddresses.nextElement());
}
}
} catch (final SocketException ignored) {
ExceptionUtils.ignoreException(ignored, "Couldn't obtain local addresses");
}
return Collections.unmodifiableSet(result);
}
/**
* Creates an array of sockets with TTL and network interface set.
*
* @param mcastTTL multicast TTL.
* @return an array of multicast sockets to broadcast on.
* @throws IOException if I/O error occurred while creating a multicast socket.
* @noinspection SocketOpenedButNotSafelyClosed, ConstantConditions
*/
private static MulticastSocket[] createSockets(final int mcastTTL) throws IOException {
Exception lastException = null; // Records last error in case we could not create any sockets
final List<MulticastSocket> socketList = new ArrayList<MulticastSocket>(11);
final Enumeration<NetworkInterface> enumeration = NetworkInterface.getNetworkInterfaces();
while (enumeration.hasMoreElements()) {
try {
final NetworkInterface netIf = enumeration.nextElement();
final MulticastSocket socket = new MulticastSocket(); // NOPMD
socket.setTimeToLive(mcastTTL);
socket.setNetworkInterface(netIf);
socket.setSendBufferSize(SEND_BUFFER_SIZE);
socketList.add(socket);
} catch (final Exception e) {
lastException = e;
ExceptionUtils.ignoreException(e, "continue to connect to those we can");
}
}
if (socketList.isEmpty()) {
throw new IOException(
"Could not create at least one multicast socket. Last error: " + lastException);
}
return socketList.toArray(new MulticastSocket[socketList.size()]);
}