1 /*
   2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 import jtreg.SkippedException;
  25 
  26 import javax.naming.directory.InitialDirContext;
  27 
  28 import java.io.IOException;
  29 import java.net.BindException;
  30 import java.net.InetAddress;
  31 import java.net.ServerSocket;
  32 
  33 /*
  34  * @test
  35  * @bug 8228580
  36  * @summary Tests that we get a DNS response when the UDP DNS server returns a
  37  *          truncated response and the TCP DNS server does not respond at all
  38  *          after connect.
  39  * @library ../lib/
  40  * @library /test/lib
  41  * @modules java.base/sun.security.util
  42  * @run main TcpTimeout
  43  */
  44 
  45 public class TcpTimeout extends DNSTestBase {
  46     private TcpDnsServer tcpDnsServer;
  47 
  48     public static void main(String[] args) throws Exception {
  49         new TcpTimeout().run(args);
  50     }
  51 
  52     @Override
  53     public void runTest() throws Exception {
  54         /* Using the default context because we rely on the default DNS client
  55         timeout setting, com.sun.jndi.dns.timeout.initial (which is currently 1000) */
  56         setContext(new InitialDirContext(env()));
  57 
  58         /* perform query */
  59         var attrs = context().getAttributes("host1");
  60         DNSTestUtils.debug(attrs);
  61         
  62         /* Note that the returned attributes are truncated and the response
  63         is not valid. */
  64         var txtAttr = attrs.get("TXT");
  65         if (txtAttr == null)
  66             throw new RuntimeException("TXT attribute missing.");
  67     }
  68 
  69     @Override
  70     public void initTest(String[] args) {
  71         /* We need to bind the TCP server on the same port the UDP server is
  72         listening to. This may not be possible if that port is in use. Retry
  73         MAX_RETRIES times relying on UDP port randomness. */
  74         final int MAX_RETRIES = 5;
  75         for (int i = 0; i < MAX_RETRIES; i++) {
  76             super.initTest(args);
  77             var udpServer = (Server) env().get(DNSTestUtils.TEST_DNS_SERVER_THREAD);
  78             int port = udpServer.getPort();
  79             try {
  80                 tcpDnsServer = new TcpDnsServer(port);
  81                 break; // success
  82             } catch (BindException be) {
  83                 DNSTestUtils.debug("Failed to bind server socket on port " + port
  84                     + ", retry no. " + (i + 1) + ", " + be.getMessage());
  85             } catch (Exception ex) {
  86                 throw new RuntimeException("Unexpected exception during initTest", ex);
  87             } finally {
  88                 if (tcpDnsServer == null) { // cleanup behind exceptions
  89                     super.cleanupTest();
  90                 }
  91             }
  92         }
  93 
  94         if (tcpDnsServer == null) {
  95             throw new SkippedException("Cannot start TCP server after "
  96                                                + MAX_RETRIES
  97                                                + " tries, skip the test");
  98         }
  99     }
 100 
 101     @Override
 102     public void cleanupTest() {
 103         super.cleanupTest();
 104         if (tcpDnsServer != null)
 105             tcpDnsServer.stopServer();
 106     }
 107 
 108     /**
 109      * A TCP server that accepts a connection and does nothing else: causes read
 110      * timeout on client side.
 111      */
 112     private static class TcpDnsServer {
 113         final ServerSocket serverSocket;
 114         
 115         TcpDnsServer(int port) throws IOException {
 116             serverSocket = new ServerSocket(port, 0, InetAddress.getLoopbackAddress());
 117             System.out.println("TcpDnsServer: listening on port " + port);
 118         }
 119 
 120         void stopServer() {
 121             try {
 122                 if (serverSocket != null)
 123                     serverSocket.close();
 124             }
 125             catch (Exception e) {}
 126         }
 127     }
 128 }