dubbo-maven-address-plugin/src/main/java/org/apache/dubbo/DubboLocalIpDetector.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.dubbo;

import java.io.IOException;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.UnknownHostException;
import java.util.Enumeration;
import java.util.Optional;
import java.util.regex.Pattern;

public class DubboLocalIpDetector {
    private static final Pattern IP_PATTERN = Pattern.compile("\\d{1,3}(\\.\\d{1,3}){3,5}$");
    private static final String ANYHOST_VALUE = "0.0.0.0";
    private static final String LOCALHOST_VALUE = "127.0.0.1";

    public static void main(String[] args) {
        System.out.println(getAddress());
    }

    public static String getAddress() {
        return getLocalAddress().getHostAddress();
    }

    private static InetAddress getLocalAddress() {
        InetAddress localAddress = null;
        try {
            localAddress = InetAddress.getLocalHost();
            Optional<InetAddress> addressOp = toValidAddress(localAddress);
            if (addressOp.isPresent()) {
                return addressOp.get();
            }
        } catch (Throwable e) {
            e.printStackTrace();
        }

        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            if (null == interfaces) {
                return localAddress;
            }
            while (interfaces.hasMoreElements()) {
                try {
                    NetworkInterface network = interfaces.nextElement();
                    if (network.isLoopback() || network.isVirtual() || !network.isUp()) {
                        continue;
                    }
                    Enumeration<InetAddress> addresses = network.getInetAddresses();
                    while (addresses.hasMoreElements()) {
                        try {
                            Optional<InetAddress> addressOp = toValidAddress(addresses.nextElement());
                            if (addressOp.isPresent()) {
                                try {
                                    if (addressOp.get().isReachable(100)) {
                                        return addressOp.get();
                                    }
                                } catch (IOException e) {
                                    // ignore
                                }
                            }
                        } catch (Throwable e) {
                            e.printStackTrace();
                        }
                    }
                } catch (Throwable e) {
                    e.printStackTrace();
                }
            }
        } catch (Throwable e) {
            e.printStackTrace();
        }
        return localAddress;
    }

    private static Optional<InetAddress> toValidAddress(InetAddress address) {
        if (address instanceof Inet6Address) {
            Inet6Address v6Address = (Inet6Address) address;
            if (isPreferIPV6Address()) {
                return Optional.ofNullable(normalizeV6Address(v6Address));
            }
        }
        if (isValidV4Address(address)) {
            return Optional.of(address);
        }
        return Optional.empty();
    }

    private static boolean isPreferIPV6Address() {
        boolean preferIpv6 = Boolean.getBoolean("java.net.preferIPv6Addresses");
        if (!preferIpv6) {
            return false;
        }
        return false;
    }

    private static InetAddress normalizeV6Address(Inet6Address address) {
        String addr = address.getHostAddress();
        int i = addr.lastIndexOf('%');
        if (i > 0) {
            try {
                return InetAddress.getByName(addr.substring(0, i) + '%' + address.getScopeId());
            } catch (UnknownHostException e) {
                e.printStackTrace();
            }
        }
        return address;
    }

    private static boolean isValidV4Address(InetAddress address) {
        if (address == null || address.isLoopbackAddress()) {
            return false;
        }
        String name = address.getHostAddress();
        boolean result = (name != null
                && IP_PATTERN.matcher(name).matches()
                && !ANYHOST_VALUE.equals(name)
                && !LOCALHOST_VALUE.equals(name));
        return result;
    }
}