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	/*
	* Copyright (c) 2002, 2019, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package java.net;

	import java.io.IOException;

	import static java.net.InetAddress.IPv6;
	import static java.net.InetAddress.PREFER_IPV6_VALUE;
	import static java.net.InetAddress.PREFER_SYSTEM_VALUE;

	/*
	* Package private implementation of InetAddressImpl for dual
	* IPv4/IPv6 stack.
	* <p>
	* If InetAddress.preferIPv6Address is true then anyLocalAddress()
	* and localHost() will return IPv6 addresses, otherwise IPv4 addresses.
	*
	* loopbackAddress() will return the first valid loopback address in
	* [IPv6 loopback, IPv4 loopback] if InetAddress.preferIPv6Address is true,
	* else [IPv4 loopback, IPv6 loopback].
	* If neither are valid it will fallback to the first address tried.
	*
	* @since 1.4
	*/
	class Inet6AddressImpl implements InetAddressImpl {

	public native String getLocalHostName() throws UnknownHostException;

	public native InetAddress[] lookupAllHostAddr(String hostname)
	throws UnknownHostException;

	public native String getHostByAddr(byte[] addr) throws UnknownHostException;

	private native boolean isReachable0(byte[] addr, int scope, int timeout,
	byte[] inf, int ttl, int if_scope)
	throws IOException;

	public boolean isReachable(InetAddress addr, int timeout,
	NetworkInterface netif, int ttl)
	throws IOException
	{
	byte[] ifaddr = null;
	int scope = -1;
	int netif_scope = -1;
	if (netif != null) {
	/*
	* Let's make sure we bind to an address of the proper family.
	* Which means same family as addr because at this point it could
	* be either an IPv6 address or an IPv4 address (case of a dual
	* stack system).
	*/
	java.util.Enumeration<InetAddress> it = netif.getInetAddresses();
	InetAddress inetaddr;
	while (it.hasMoreElements()) {
	inetaddr = it.nextElement();
	if (inetaddr.getClass().isInstance(addr)) {
	ifaddr = inetaddr.getAddress();
	if (inetaddr instanceof Inet6Address) {
	netif_scope = ((Inet6Address) inetaddr).getScopeId();
	}
	break;
	}
	}
	if (ifaddr == null) {
	// Interface doesn't support the address family of
	// the destination
	return false;
	}
	}
	if (addr instanceof Inet6Address)
	scope = ((Inet6Address) addr).getScopeId();
	return isReachable0(addr.getAddress(), scope, timeout, ifaddr, ttl, netif_scope);
	}

	public synchronized InetAddress anyLocalAddress() {
	if (anyLocalAddress == null) {
	if (InetAddress.preferIPv6Address == PREFER_IPV6_VALUE \|\|
	InetAddress.preferIPv6Address == PREFER_SYSTEM_VALUE) {
	anyLocalAddress = new Inet6Address();
	anyLocalAddress.holder().hostName = "::";
	} else {
	anyLocalAddress = (new Inet4AddressImpl()).anyLocalAddress();
	}
	}
	return anyLocalAddress;
	}

	public synchronized InetAddress loopbackAddress() {
	if (loopbackAddress == null) {
	boolean preferIPv6Address =
	InetAddress.preferIPv6Address == PREFER_IPV6_VALUE \|\|
	InetAddress.preferIPv6Address == PREFER_SYSTEM_VALUE;

	for (int i = 0; i < 2; i++) {
	InetAddress address;
	// Order the candidate addresses by preference.
	if (i == (preferIPv6Address ? 0 : 1)) {
	address = new Inet6Address("localhost",
	new byte[]{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01});
	} else {
	address = new Inet4Address("localhost", new byte[]{ 0x7f,0x00,0x00,0x01 });
	}
	if (i == 0) {
	// In case of failure, default to the preferred address.
	loopbackAddress = address;
	}
	try {
	if (!NetworkInterface.isBoundInetAddress(address)) {
	continue;
	}
	} catch (SocketException e) {
	continue;
	}
	loopbackAddress = address;
	break;
	}
	}
	return loopbackAddress;
	}

	private InetAddress anyLocalAddress;
	private InetAddress loopbackAddress;
	}

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