Java example source code file (SelectWhenRefused.java)

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Java - Java tags/keywords

bytebuffer, datagramchannel, greetings, inetsocketaddress, ioexception, net, network, nio, portunreachableexception, runtimeexception, selector, selectwhenrefused, unexpected

The SelectWhenRefused.java Java example source code

/*
 * Copyright (c) 2010, 2011, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/* @test
 * @bug 6935563 7044870
 * @summary Test that Selector does not select an unconnected DatagramChannel when
 *    ICMP port unreachable received
 */

import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.net.*;
import java.io.IOException;

public class SelectWhenRefused {

    public static void main(String[] args) throws IOException {
        DatagramChannel dc1 = DatagramChannel.open().bind(new InetSocketAddress(0));
        int port = dc1.socket().getLocalPort();

        // datagram sent to this address should be refused
        SocketAddress refuser = new InetSocketAddress(InetAddress.getLocalHost(), port);

        DatagramChannel dc = DatagramChannel.open().bind(new InetSocketAddress(0));
        dc1.close();

        Selector sel = Selector.open();
        try {
            dc.configureBlocking(false);
            dc.register(sel, SelectionKey.OP_READ);

            /* Test 1: not connected so ICMP port unreachable should not be received */
            sendDatagram(dc, refuser);
            int n = sel.select(2000);
            if (n > 0) {
                sel.selectedKeys().clear();
                // BindException will be thrown if another service is using
                // our expected refuser port, cannot run just exit.
                DatagramChannel.open().bind(refuser).close();
                throw new RuntimeException("Unexpected wakeup");
            }

            /* Test 2: connected so ICMP port unreachable may be received */
            dc.connect(refuser);
            try {
                sendDatagram(dc, refuser);
                n = sel.select(2000);
                if (n > 0) {
                    sel.selectedKeys().clear();
                    try {
                        n = dc.read(ByteBuffer.allocate(100));
                        throw new RuntimeException("Unexpected datagram received");
                    } catch (PortUnreachableException pue) {
                        // expected
                    }
                }
            } finally {
                dc.disconnect();
            }

            /* Test 3: not connected so ICMP port unreachable should not be received */
            sendDatagram(dc, refuser);
            n = sel.select(2000);
            if (n > 0) {
                throw new RuntimeException("Unexpected wakeup after disconnect");
            }

        } catch(BindException e) {
            // Do nothing, some other test has used this port
        } finally {
            sel.close();
            dc.close();
        }
    }

    static void sendDatagram(DatagramChannel dc, SocketAddress remote)
        throws IOException
    {
        ByteBuffer bb = ByteBuffer.wrap("Greetings!".getBytes());
        dc.send(bb, remote);
    }
}