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 * Copyright (c) 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.

 *

 * 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.

 *

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 */

/* @test

 * @bug 8234805

 * @summary Test that DatagramChannel.receive returns the expected sender address

 * @run main ManySenders

 * @run main/othervm -Djava.net.preferIPv4Stack=true ManySenders

 */

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.net.NetworkInterface;

import java.net.SocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.DatagramChannel;

import java.util.List;

import java.util.stream.Collectors;

import java.util.stream.Stream;

public class ManySenders {

    public static void main(String[] args) throws Exception {

        // use addresses on interfaces that have the loopback and local host

        InetAddress lh = InetAddress.getLocalHost();

        InetAddress lb = InetAddress.getLoopbackAddress();

        List<InetAddress> addresses = Stream.concat(

                NetworkInterface.getByInetAddress(lh).inetAddresses(),

                NetworkInterface.getByInetAddress(lb).inetAddresses())

                .filter(ia -> !ia.isAnyLocalAddress())

                .distinct()

                .collect(Collectors.toList());

        // bind DatagramChannel to wildcard address so it can receive from any address

        try (DatagramChannel reader = DatagramChannel.open()) {

            reader.bind(new InetSocketAddress(0));

            for (InetAddress address : addresses) {

                System.out.format("%n-- %s --%n", address.getHostAddress());

                // send 3 datagrams from the given address to the reader

                test(3, address, reader);

            }

        }

    }

    static void test(int count, InetAddress address, DatagramChannel reader) throws Exception {

        int remotePort = reader.socket().getLocalPort();

        InetSocketAddress remote = new InetSocketAddress(address, remotePort);

        try (DatagramChannel sender = DatagramChannel.open()) {

            sender.bind(new InetSocketAddress(address, 0));

            SocketAddress local = sender.getLocalAddress();

            byte[] bytes = serialize(local);

            SocketAddress previousSource = null;

            for (int i = 0; i < count; i++) {

                System.out.format("send %s -> %s%n", local, remote);

                sender.send(ByteBuffer.wrap(bytes), remote);

                ByteBuffer bb = ByteBuffer.allocate(1000);

                SocketAddress source = reader.receive(bb);

                System.out.format("received datagram from %s%n", source);

                // check source address and payload

                SocketAddress payload = deserialize(bb.array());

                if (!source.equals(local))

                    throw new RuntimeException("source=" + source + ", expected=" + local);

                if (!payload.equals(local))

                    throw new RuntimeException("payload=" + payload + ", expected=" + local);

                // check that cached source was used

                if (previousSource == null) {

                    previousSource = source;

                } else if (source != previousSource) {

                    throw new RuntimeException("Cached SocketAddress not returned");

                }

            }

        }

    }

    private static byte[] serialize(SocketAddress address) throws Exception {

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        ObjectOutputStream oos = new ObjectOutputStream(baos);

        oos.writeObject(address);

        oos.close();

        return baos.toByteArray();

    }

    private static SocketAddress deserialize(byte[] bytes) throws Exception {

        ByteArrayInputStream bais = new ByteArrayInputStream(bytes);

        ObjectInputStream ois = new ObjectInputStream(bais);

        return (SocketAddress) ois.readObject();

    }

}