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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 * 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 8765432
 * @summary Tests async close while receiving packets with zero bytes
 * @run testng/othervm AsyncCloseReceiveEmpty
 */

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.security.Permission;
import org.testng.annotations.Test;
import static java.lang.String.format;
import static java.lang.System.out;
import static org.testng.Assert.*;

@Test
public class AsyncCloseReceiveEmpty {

    /** Tests asynchronous close when a packet with zero bytes has been received. */
    public void testUnconnectedReceive() throws Exception {
        out.println("\n\n--- testUnconnectedReceive ---");
        var dc1 = DatagramChannel.open().bind(null);
        var dc2 = DatagramChannel.open();

        var address = new InetSocketAddress("localhost", dc1.socket().getLocalPort());
        out.println(format("Sending empty packet to %s", address));
        dc2.send(ByteBuffer.wrap(new byte[0]), address);

        // SM being used here since it provides a convenient means of injecting
        // close where we want it
        SecurityManager sm = new SecurityManager() {
            @Override
            public void checkAccept(String host, int port) {
                out.println(format("Allowing packet from %s:%d. Closing channel", host, port));
                try { dc1.close(); out.println("closed"); }
                catch (IOException e) { fail("UNEXPECTED", e); }
            }
            @Override
            public void checkPermission(Permission perm) { }
        };

        System.setSecurityManager(sm);
        try {
            ByteBuffer bb = ByteBuffer.allocate(10);
            SocketAddress sa = dc1.receive(bb);
            out.println(format("received from: [%s], data: [%s]", sa, bb));
            bb.flip();
            assertEquals(bb.remaining(), 0);
        } finally {
            System.setSecurityManager(null);
        }
    }

    /** Sanity to ensure packets with zero bytes can be sent and received. */
    public void sanity() throws Exception {
        out.println("\n\n--- sanity ---");
        var dc1 = DatagramChannel.open().bind(null);
        var dc2 = DatagramChannel.open();

        var address = new InetSocketAddress("localhost", dc1.socket().getLocalPort());
        out.println(format("Sending empty packet to %s", address));
        for (int i=0; i<10; i++)
            dc2.send(ByteBuffer.wrap(new byte[0]), address);

        ByteBuffer bb = ByteBuffer.allocate(10);
        for (int i=0; i<10; i++) {
            bb.clear();
            SocketAddress sa = dc1.receive(bb);
            out.println(format("received from: [%s], data: [%s]", sa, bb));
            bb.flip();
            assertEquals(bb.remaining(), 0);
        }
    }
}