NetUtilInitializations Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/NetUtilInitializations.java lines 34–188

final class NetUtilInitializations {
    /**
     * The logger being used by this class
     */
    private static final InternalLogger logger = InternalLoggerFactory.getInstance(NetUtilInitializations.class);

    private NetUtilInitializations() {
    }

    static Inet4Address createLocalhost4() {
        byte[] LOCALHOST4_BYTES = {127, 0, 0, 1};

        Inet4Address localhost4 = null;
        try {
            localhost4 = (Inet4Address) InetAddress.getByAddress("localhost", LOCALHOST4_BYTES);
        } catch (Exception e) {
            // We should not get here as long as the length of the address is correct.
            PlatformDependent.throwException(e);
        }

        return localhost4;
    }

    static Inet6Address createLocalhost6() {
        byte[] LOCALHOST6_BYTES = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};

        Inet6Address localhost6 = null;
        try {
            localhost6 = (Inet6Address) InetAddress.getByAddress("localhost", LOCALHOST6_BYTES);
        } catch (Exception e) {
            // We should not get here as long as the length of the address is correct.
            PlatformDependent.throwException(e);
        }

        return localhost6;
    }

    static Collection<NetworkInterface> networkInterfaces() {
        List<NetworkInterface> networkInterfaces = new ArrayList<NetworkInterface>();
        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            if (interfaces != null) {
                while (interfaces.hasMoreElements()) {
                    networkInterfaces.add(interfaces.nextElement());
                }
            }
        } catch (SocketException e) {
            logger.warn("Failed to retrieve the list of available network interfaces", e);
        } catch (NullPointerException e) {
            if (!PlatformDependent.isAndroid()) {
                throw e;
            }
            // Might happen on earlier version of Android.
            // See https://developer.android.com/reference/java/net/NetworkInterface#getNetworkInterfaces()
        }
        return Collections.unmodifiableList(networkInterfaces);
    }

    static NetworkIfaceAndInetAddress determineLoopback(
            Collection<NetworkInterface> networkInterfaces, Inet4Address localhost4, Inet6Address localhost6) {
        // Retrieve the list of available network interfaces.
        List<NetworkInterface> ifaces = new ArrayList<NetworkInterface>();
        for (NetworkInterface iface: networkInterfaces) {
            // Use the interface with proper INET addresses only.
            if (SocketUtils.addressesFromNetworkInterface(iface).hasMoreElements()) {
                ifaces.add(iface);
            }
        }

        // Find the first loopback interface available from its INET address (127.0.0.1 or ::1)
        // Note that we do not use NetworkInterface.isLoopback() in the first place because it takes long time
        // on a certain environment. (e.g. Windows with -Djava.net.preferIPv4Stack=true)
        NetworkInterface loopbackIface = null;
        InetAddress loopbackAddr = null;
        loop: for (NetworkInterface iface: ifaces) {
            for (Enumeration<InetAddress> i = SocketUtils.addressesFromNetworkInterface(iface); i.hasMoreElements();) {
                InetAddress addr = i.nextElement();
                if (addr.isLoopbackAddress()) {
                    // Found
                    loopbackIface = iface;
                    loopbackAddr = addr;