/*

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 * questions.

 */

/**

 * @test

 * @run testng/othervm -Dsun.net.maxDatagramSockets=32 UdpSocket

 * @summary Basic test for a Socket to a UDP socket

 */

import java.io.IOException;

import java.lang.ref.WeakReference;

import java.net.InetAddress;

import java.net.InetSocketAddress;

import java.net.Socket;

import java.net.SocketAddress;

import java.nio.ByteBuffer;

import java.nio.channels.DatagramChannel;

import java.security.Permission;

import java.util.Arrays;

import java.util.ArrayList;

import java.util.ArrayDeque;

import java.util.Deque;

import org.testng.annotations.Test;

import static org.testng.Assert.*;

@Test

public class UdpSocket {

    /**

     * Test using the Socket API to send/receive datagrams

     */

    public void testSendReceive() throws IOException {

        final String MESSAGE = "hello";

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

            var loopback = InetAddress.getLoopbackAddress();

            dc.bind(new InetSocketAddress(loopback, 0));

            int port = ((InetSocketAddress) dc.getLocalAddress()).getPort();

            try (Socket s = new Socket(loopback, port, false)) {

                // send datagram with socket output stream

                byte[] array1 = MESSAGE.getBytes("UTF-8");

                s.getOutputStream().write(array1);

                // receive the datagram

                var buf = ByteBuffer.allocate(100);

                SocketAddress remote = dc.receive(buf);

                buf.flip();

                assertTrue(buf.remaining() == MESSAGE.length(), "Unexpected size");

                // echo the datagram

                dc.send(buf, remote);

                // receive datagram with the socket input stream

                byte[] array2 = new byte[100];

                int n = s.getInputStream().read(array2);

                assertTrue(n == MESSAGE.length(), "Unexpected size");

            }

        }

    }

    /**

     * Test that the number of UDP sockets is limited when running with a

     * security manager.

     */

    public void testMaxSockets() throws Exception {

        int limit = Integer.getInteger("sun.net.maxDatagramSockets");

        // security manager grants all permissions

        var securityManager = new SecurityManager() {

            @Override public void checkPermission(Permission perm) { }

        };

        System.setSecurityManager(securityManager);

        Deque<Socket> sockets = new ArrayDeque<>();

        try {

            // create the maximum number of sockets

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

                sockets.offer(newUdpSocket());

            }

            // try to create another socket - should fail

            try {

                Socket s = newUdpSocket();

                s.close();

                assertTrue(false);

            } catch (IOException expected) { }

            // close one socket

            sockets.pop().close();

            // try to create another socket - should succeed

            Socket s = newUdpSocket();

            // unreference the socket and wait for it to be closed by the cleaner

            var ref = new WeakReference<>(s);

            s = null;

            while (ref.get() != null) {

                System.gc();

                Thread.sleep(100);

            }

            // try to create another socket - should succeed

            s = newUdpSocket();

            s.close();

        } finally {

            closeAll(sockets);

            System.setSecurityManager(null);

        }

    }

    private Socket newUdpSocket() throws IOException {

        return new Socket(InetAddress.getLoopbackAddress(), 8000, false);

    }

    private void closeAll(Deque<Socket> sockets) throws IOException {

        Socket s;

        while ((s = sockets.poll()) != null) {

            s.close();

        }

    }

}