/*

 * 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;

}