Java Host Address Get getHostAddress()

Description

Get the host IP address Use env(IFACE) to select an interface or env(IP) to select a specific address to prefer IPv6 use: java.net.preferIPv6Stack=true

License

Open Source License

Return

return the host IP address or 127.0.0.1 (::1)

Declaration

public static InetAddress getHostAddress()

Method Source Code

//package com.java2s;
/* /*w  w w  .  jav  a  2  s.  c  om*/
 * Copyright (c) 2013 Universit? della Svizzera italiana (USI)
 * 
 * This file is part of URingPaxos.
 *
 * URingPaxos is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * URingPaxos is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with URingPaxos.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;

import java.util.Enumeration;

public class Main {
    /**
     * Get the host IP address
     * 
     * Use env(IFACE) to select an interface or
     * env(IP) to select a specific address
     * 
     * to prefer IPv6 use: java.net.preferIPv6Stack=true
     * 
     * @return return the host IP address or 127.0.0.1 (::1)
     */
    public static InetAddress getHostAddress() {
        boolean ipv6 = false;
        String pv4 = System.getProperty("java.net.preferIPv4Stack");
        String pv6 = System.getProperty("java.net.preferIPv6Stack");
        if (pv4 != null && pv4.equals("false")) {
            ipv6 = true;
        }
        if (pv6 != null && pv6.equals("true")) {
            ipv6 = true;
        }
        try {
            String iface = System.getenv("IFACE");
            String public_ip = System.getenv("IP");
            if (public_ip != null) {
                return InetAddress.getByName(public_ip);
            }
            Enumeration<NetworkInterface> ni = NetworkInterface.getNetworkInterfaces();
            while (ni.hasMoreElements()) {
                NetworkInterface n = ni.nextElement();
                if (iface == null || n.getDisplayName().equals(iface)) {
                    Enumeration<InetAddress> ia = n.getInetAddresses();
                    while (ia.hasMoreElements()) {
                        InetAddress addr = ia.nextElement();
                        if (!(addr.isLinkLocalAddress() || addr.isLoopbackAddress()
                                || addr.toString().contains("192.168.122"))) {
                            if (addr instanceof Inet6Address && ipv6) {
                                return addr;
                            } else if (addr instanceof Inet4Address && !ipv6) {
                                return addr;
                            }
                        }
                    }
                }
            }
            return InetAddress.getLoopbackAddress();
        } catch (SocketException | UnknownHostException e) {
            return InetAddress.getLoopbackAddress();
        }
    }
}