/*
 * 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

import jtreg.SkippedException;

import javax.naming.directory.InitialDirContext;

import java.io.IOException;
import java.net.BindException;
import java.net.InetAddress;
import java.net.ServerSocket;

import static java.util.concurrent.TimeUnit.NANOSECONDS;
import static jdk.test.lib.Utils.adjustTimeout;

/*
 * @test
 * @bug 8228580
 * @summary Tests that we get a DNS response when the UDP DNS server returns a
 *          truncated response and the TCP DNS server does not respond at all
 *          after connect.
 * @library ../lib/
 * @library /test/lib
 * @modules java.base/sun.security.util
 * @run main TcpTimeout
 * @run main TcpTimeout -Dcom.sun.jndi.dns.timeout.initial=5000
 */

public class TcpTimeout extends DNSTestBase {
    private TcpDnsServer tcpDnsServer;
    
    /* The acceptable variation in timeout measurement. */
    private static final long TOLERANCE = adjustTimeout(5_000);
    
    public static void main(String[] args) throws Exception {
        new TcpTimeout().run(args);
    }

    @Override
    public void runTest() throws Exception {
        /* Default timeout value is 1 second, as stated in jdk.naming.dns
           module docs. */
        long timeout = 1_000;
        var envTimeout = env().get("com.sun.jndi.dns.timeout.initial");
        if (envTimeout != null)
            timeout = Long.parseLong(String.valueOf(envTimeout));

        setContext(new InitialDirContext(env()));
        
        long startNanos = System.nanoTime();

        /* perform query */
        var attrs = context().getAttributes("host1");

        long elapsed = NANOSECONDS.toMillis(System.nanoTime() - startNanos);
        if (elapsed < timeout || elapsed > timeout + TOLERANCE) {
            throw new RuntimeException("Query took " + elapsed + " ms. "
                + ". Timeout value is " + timeout);
        }

        DNSTestUtils.debug(attrs);

        /* Note that the returned attributes are truncated and the response
        is not valid. */
        var txtAttr = attrs.get("TXT");
        if (txtAttr == null)
            throw new RuntimeException("TXT attribute missing.");
    }

    @Override
    public void initTest(String[] args) {
        /* We need to bind the TCP server on the same port UDP server is
        listening to. This maybe not be possible if the port is in use. Retry
        several times relaying on UDP port randomness. */
        for (int i = 0; i < 5; i++) {
            super.initTest(args);
            var udpServer = (Server) env().get(DNSTestUtils.TEST_DNS_SERVER_THREAD);
            int port = udpServer.getPort();
            try {
                tcpDnsServer = new TcpDnsServer(port);
                break; // success
            } catch (BindException be) {
                DNSTestUtils.debug("Failed to bind server socket on port " + port
                    + ", retry no. " + (i + 1));
            } catch (Exception ex) {
                throw new RuntimeException("Unexpected exception during initTest", ex);
            } finally {
                if (tcpDnsServer == null) { // cleaup behind exceptions
                    super.cleanupTest();
                }
            }
        }

        if (tcpDnsServer == null) {
            throw new SkippedException("Cannot start TCP server after 5 tries, skip test");
        }
    }

    @Override
    public void cleanupTest() {
        super.cleanupTest();
        if (tcpDnsServer != null)
            tcpDnsServer.stopServer();
    }

    /**
     * A TCP server that accepts a connection and does nothing else: causes read
     * timeout on client side.
     */
    private static class TcpDnsServer {
        final ServerSocket serverSocket;
        
        TcpDnsServer(int port) throws IOException {
            serverSocket = new ServerSocket(port, 0, InetAddress.getLoopbackAddress());
            System.out.println("TcpDnsServer: listening on port " + port);
        }

        void stopServer() {
            try {
                if (serverSocket != null)
                    serverSocket.close();
            }
            catch (Exception e) {}
        }
    }
}