8144566: Custom HostnameVerifier disables SNI extension
authorxuelei
Fri, 22 Apr 2016 09:27:35 +0000
changeset 37601 6517589dcc94
parent 37600 137d2faf75ac
child 37602 3a9532bbd89e
8144566: Custom HostnameVerifier disables SNI extension Reviewed-by: mullan, wetmore
jdk/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
jdk/test/javax/net/ssl/ServerName/BestEffortOnLazyConnected.java
jdk/test/sun/net/www/protocol/https/HttpsURLConnection/ImpactOnSNI.java
--- a/jdk/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java	Fri Apr 22 17:07:54 2016 +0800
+++ b/jdk/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java	Fri Apr 22 09:27:35 2016 +0000
@@ -209,6 +209,12 @@
     Collection<SNIMatcher>      sniMatchers =
                                     Collections.<SNIMatcher>emptyList();
 
+    // Is the serverNames set to empty with SSLParameters.setServerNames()?
+    private boolean             noSniExtension = false;
+
+    // Is the sniMatchers set to empty with SSLParameters.setSNIMatchers()?
+    private boolean             noSniMatcher = false;
+
     // Configured application protocol values
     String[] applicationProtocols = new String[0];
 
@@ -642,6 +648,11 @@
         }
 
         super.connect(endpoint, timeout);
+
+        if (host == null || host.length() == 0) {
+            useImplicitHost(false);
+        }
+
         doneConnect();
     }
 
@@ -2098,41 +2109,62 @@
         outputRecord.setVersion(protocolVersion);
     }
 
+    //
+    // ONLY used by ClientHandshaker for the server hostname during handshaking
+    //
     synchronized String getHost() {
         // Note that the host may be null or empty for localhost.
         if (host == null || host.length() == 0) {
-            if (!trustNameService) {
-                // If the local name service is not trustworthy, reverse host
-                // name resolution should not be performed for endpoint
-                // identification.  Use the application original specified
-                // hostname or IP address instead.
-                host = getOriginalHostname(getInetAddress());
-            } else {
-                host = getInetAddress().getHostName();
-            }
+            useImplicitHost(true);
         }
 
         return host;
     }
 
     /*
-     * Get the original application specified hostname.
+     * Try to set and use the implicit specified hostname
      */
-    private static String getOriginalHostname(InetAddress inetAddress) {
-        /*
-         * Get the original hostname via jdk.internal.misc.SharedSecrets.
-         */
-        JavaNetInetAddressAccess jna = SharedSecrets.getJavaNetInetAddressAccess();
-        String originalHostname = jna.getOriginalHostName(inetAddress);
+    private synchronized void useImplicitHost(boolean noSniUpdate) {
 
-        /*
-         * If no application specified hostname, use the IP address.
-         */
-        if (originalHostname == null || originalHostname.length() == 0) {
-            originalHostname = inetAddress.getHostAddress();
+        // Note: If the local name service is not trustworthy, reverse
+        // host name resolution should not be performed for endpoint
+        // identification.  Use the application original specified
+        // hostname or IP address instead.
+
+        // Get the original hostname via jdk.internal.misc.SharedSecrets
+        InetAddress inetAddress = getInetAddress();
+        if (inetAddress == null) {      // not connected
+            return;
         }
 
-        return originalHostname;
+        JavaNetInetAddressAccess jna =
+                SharedSecrets.getJavaNetInetAddressAccess();
+        String originalHostname = jna.getOriginalHostName(inetAddress);
+        if ((originalHostname != null) &&
+                (originalHostname.length() != 0)) {
+
+            host = originalHostname;
+            if (!noSniUpdate && serverNames.isEmpty() && !noSniExtension) {
+                serverNames =
+                        Utilities.addToSNIServerNameList(serverNames, host);
+
+                if (!roleIsServer &&
+                        (handshaker != null) && !handshaker.started()) {
+                    handshaker.setSNIServerNames(serverNames);
+                }
+            }
+
+            return;
+        }
+
+        // No explicitly specified hostname, no server name indication.
+        if (!trustNameService) {
+            // The local name service is not trustworthy, use IP address.
+            host = inetAddress.getHostAddress();
+        } else {
+            // Use the underlying reverse host name resolution service.
+            host = getInetAddress().getHostName();
+        }
     }
 
     // ONLY used by HttpsClient to setup the URI specified hostname
@@ -2144,6 +2176,10 @@
         this.host = host;
         this.serverNames =
             Utilities.addToSNIServerNameList(this.serverNames, this.host);
+
+        if (!roleIsServer && (handshaker != null) && !handshaker.started()) {
+            handshaker.setSNIServerNames(serverNames);
+        }
     }
 
     /**
@@ -2533,8 +2569,21 @@
         // the super implementation does not handle the following parameters
         params.setEndpointIdentificationAlgorithm(identificationProtocol);
         params.setAlgorithmConstraints(algorithmConstraints);
-        params.setSNIMatchers(sniMatchers);
-        params.setServerNames(serverNames);
+
+        if (sniMatchers.isEmpty() && !noSniMatcher) {
+            // 'null' indicates none has been set
+            params.setSNIMatchers(null);
+        } else {
+            params.setSNIMatchers(sniMatchers);
+        }
+
+        if (serverNames.isEmpty() && !noSniExtension) {
+            // 'null' indicates none has been set
+            params.setServerNames(null);
+        } else {
+            params.setServerNames(serverNames);
+        }
+
         params.setUseCipherSuitesOrder(preferLocalCipherSuites);
         params.setMaximumPacketSize(maximumPacketSize);
         params.setApplicationProtocols(applicationProtocols);
@@ -2568,11 +2617,13 @@
 
         List<SNIServerName> sniNames = params.getServerNames();
         if (sniNames != null) {
+            noSniExtension = sniNames.isEmpty();
             serverNames = sniNames;
         }
 
         Collection<SNIMatcher> matchers = params.getSNIMatchers();
         if (matchers != null) {
+            noSniMatcher = matchers.isEmpty();
             sniMatchers = matchers;
         }
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/javax/net/ssl/ServerName/BestEffortOnLazyConnected.java	Fri Apr 22 09:27:35 2016 +0000
@@ -0,0 +1,337 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+//
+// SunJSSE does not support dynamic system properties, no way to re-use
+// system properties in samevm/agentvm mode.
+//
+
+/**
+ * @test
+ * @bug 8144566
+ * @summary Custom HostnameVerifier disables SNI extension
+ * @run main/othervm BestEffortOnLazyConnected
+ */
+
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+import java.util.*;
+import java.net.*;
+import javax.net.ssl.*;
+
+public class BestEffortOnLazyConnected {
+
+    /*
+     * =============================================================
+     * Set the various variables needed for the tests, then
+     * specify what tests to run on each side.
+     */
+
+    /*
+     * Should we run the client or server in a separate thread?
+     * Both sides can throw exceptions, but do you have a preference
+     * as to which side should be the main thread.
+     */
+    private static final boolean separateServerThread = true;
+
+    /*
+     * Where do we find the keystores?
+     */
+    private static final String pathToStores = "../etc";
+    private static final String keyStoreFile = "keystore";
+    private static final String trustStoreFile = "truststore";
+    private static final String passwd = "passphrase";
+
+    /*
+     * Is the server ready to serve?
+     */
+    private static volatile boolean serverReady = false;
+
+    /*
+     * Turn on SSL debugging?
+     */
+    private static final boolean debug = false;
+
+    /*
+     * the fully qualified domain name of localhost
+     */
+    private static String hostname = null;
+
+    /*
+     * If the client or server is doing some kind of object creation
+     * that the other side depends on, and that thread prematurely
+     * exits, you may experience a hang.  The test harness will
+     * terminate all hung threads after its timeout has expired,
+     * currently 3 minutes by default, but you might try to be
+     * smart about it....
+     */
+
+    /*
+     * Define the server side of the test.
+     *
+     * If the server prematurely exits, serverReady will be set to true
+     * to avoid infinite hangs.
+     */
+    private void doServerSide() throws Exception {
+        SSLServerSocketFactory sslssf =
+            (SSLServerSocketFactory) SSLServerSocketFactory.getDefault();
+        try (SSLServerSocket sslServerSocket =
+                (SSLServerSocket) sslssf.createServerSocket(serverPort)) {
+
+            serverPort = sslServerSocket.getLocalPort();
+
+            /*
+             * Signal Client, we're ready for his connect.
+             */
+            serverReady = true;
+
+            try (SSLSocket sslSocket = (SSLSocket)sslServerSocket.accept()) {
+                InputStream sslIS = sslSocket.getInputStream();
+                OutputStream sslOS = sslSocket.getOutputStream();
+
+                sslIS.read();
+                sslOS.write(85);
+                sslOS.flush();
+
+                ExtendedSSLSession session =
+                        (ExtendedSSLSession)sslSocket.getSession();
+                if (session.getRequestedServerNames().isEmpty()) {
+                    throw new Exception("No expected Server Name Indication");
+                }
+            }
+        }
+    }
+
+    /*
+     * Define the client side of the test.
+     *
+     * If the server prematurely exits, serverReady will be set to true
+     * to avoid infinite hangs.
+     */
+    private void doClientSide() throws Exception {
+
+        /*
+         * Wait for server to get started.
+         */
+        while (!serverReady) {
+            Thread.sleep(50);
+        }
+
+        SSLSocketFactory sslsf =
+            (SSLSocketFactory) SSLSocketFactory.getDefault();
+
+        try (SSLSocket sslSocket = (SSLSocket)sslsf.createSocket()) {
+
+            sslSocket.connect(new InetSocketAddress(hostname, serverPort), 0);
+
+            InputStream sslIS = sslSocket.getInputStream();
+            OutputStream sslOS = sslSocket.getOutputStream();
+
+            sslOS.write(280);
+            sslOS.flush();
+            sslIS.read();
+        }
+    }
+
+
+    /*
+     * =============================================================
+     * The remainder is just support stuff
+     */
+
+    // use any free port by default
+    private volatile int serverPort = 0;
+
+    private volatile Exception serverException = null;
+    private volatile Exception clientException = null;
+
+    public static void main(String[] args) throws Exception {
+        String keyFilename =
+            System.getProperty("test.src", ".") + "/" + pathToStores +
+                "/" + keyStoreFile;
+        String trustFilename =
+            System.getProperty("test.src", ".") + "/" + pathToStores +
+                "/" + trustStoreFile;
+
+        System.setProperty("javax.net.ssl.keyStore", keyFilename);
+        System.setProperty("javax.net.ssl.keyStorePassword", passwd);
+        System.setProperty("javax.net.ssl.trustStore", trustFilename);
+        System.setProperty("javax.net.ssl.trustStorePassword", passwd);
+
+        if (debug) {
+            System.setProperty("javax.net.debug", "all");
+        }
+
+        try {
+            hostname = InetAddress.getLocalHost().getCanonicalHostName();
+        } catch (UnknownHostException uhe) {
+            System.out.println(
+                "Ignore the test as the local hostname cannot be determined");
+
+            return;
+        }
+
+        System.out.println(
+                "The fully qualified domain name of the local host is " +
+                hostname);
+        // Ignore the test if the hostname does not sound like a domain name.
+        if ((hostname == null) || hostname.isEmpty() ||
+                hostname.startsWith("localhost") ||
+                Character.isDigit(hostname.charAt(hostname.length() - 1))) {
+
+            System.out.println("Ignore the test as the local hostname " +
+                    "cannot be determined as fully qualified domain name");
+
+            return;
+        }
+
+        /*
+         * Start the tests.
+         */
+        new BestEffortOnLazyConnected();
+    }
+
+    private Thread clientThread = null;
+    private Thread serverThread = null;
+
+    /*
+     * Primary constructor, used to drive remainder of the test.
+     *
+     * Fork off the other side, then do your work.
+     */
+    BestEffortOnLazyConnected() throws Exception {
+        try {
+            if (separateServerThread) {
+                startServer(true);
+                startClient(false);
+            } else {
+                startClient(true);
+                startServer(false);
+            }
+        } catch (Exception e) {
+            // swallow for now.  Show later
+        }
+
+        /*
+         * Wait for other side to close down.
+         */
+        if (separateServerThread) {
+            serverThread.join();
+        } else {
+            clientThread.join();
+        }
+
+        /*
+         * When we get here, the test is pretty much over.
+         * Which side threw the error?
+         */
+        Exception local;
+        Exception remote;
+        String whichRemote;
+
+        if (separateServerThread) {
+            remote = serverException;
+            local = clientException;
+            whichRemote = "server";
+        } else {
+            remote = clientException;
+            local = serverException;
+            whichRemote = "client";
+        }
+
+        /*
+         * If both failed, return the curthread's exception, but also
+         * print the remote side Exception
+         */
+        if ((local != null) && (remote != null)) {
+            System.out.println(whichRemote + " also threw:");
+            remote.printStackTrace();
+            System.out.println();
+            throw local;
+        }
+
+        if (remote != null) {
+            throw remote;
+        }
+
+        if (local != null) {
+            throw local;
+        }
+    }
+
+    private void startServer(boolean newThread) throws Exception {
+        if (newThread) {
+            serverThread = new Thread() {
+                public void run() {
+                    try {
+                        doServerSide();
+                    } catch (Exception e) {
+                        /*
+                         * Our server thread just died.
+                         *
+                         * Release the client, if not active already...
+                         */
+                        System.err.println("Server died...");
+                        serverReady = true;
+                        serverException = e;
+                    }
+                }
+            };
+            serverThread.start();
+        } else {
+            try {
+                doServerSide();
+            } catch (Exception e) {
+                serverException = e;
+            } finally {
+                serverReady = true;
+            }
+        }
+    }
+
+    private void startClient(boolean newThread) throws Exception {
+        if (newThread) {
+            clientThread = new Thread() {
+                public void run() {
+                    try {
+                        doClientSide();
+                    } catch (Exception e) {
+                        /*
+                         * Our client thread just died.
+                         */
+                        System.err.println("Client died...");
+                        clientException = e;
+                    }
+                }
+            };
+            clientThread.start();
+        } else {
+            try {
+                doClientSide();
+            } catch (Exception e) {
+                clientException = e;
+            }
+        }
+    }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/sun/net/www/protocol/https/HttpsURLConnection/ImpactOnSNI.java	Fri Apr 22 09:27:35 2016 +0000
@@ -0,0 +1,390 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+//
+// SunJSSE does not support dynamic system properties, no way to re-use
+// system properties in samevm/agentvm mode.
+//
+
+/*
+ * @test
+ * @bug 8144566
+ * @summary Custom HostnameVerifier disables SNI extension
+ * @run main/othervm ImpactOnSNI
+ */
+
+import java.io.*;
+import java.net.*;
+import javax.net.ssl.*;
+
+public class ImpactOnSNI {
+
+    /*
+     * =============================================================
+     * Set the various variables needed for the tests, then
+     * specify what tests to run on each side.
+     */
+
+    /*
+     * Should we run the client or server in a separate thread?
+     * Both sides can throw exceptions, but do you have a preference
+     * as to which side should be the main thread.
+     */
+    private static final boolean separateServerThread = true;
+
+    /*
+     * Where do we find the keystores?
+     */
+    private static final String pathToStores =
+                                        "../../../../../../javax/net/ssl/etc";
+    private static final String keyStoreFile = "keystore";
+    private static final String trustStoreFile = "truststore";
+    private static final String passwd = "passphrase";
+
+    /*
+     * Is the server ready to serve?
+     */
+    private static volatile boolean serverReady = false;
+
+    /*
+     * Is the connection ready to close?
+     */
+    private static volatile boolean closeReady = false;
+
+    /*
+     * Turn on SSL debugging?
+     */
+    private static final boolean debug = false;
+
+    /*
+     * Message posted
+     */
+    private static final String postMsg = "HTTP post on a https server";
+
+    /*
+     * the fully qualified domain name of localhost
+     */
+    private static String hostname = null;
+
+    /*
+     * If the client or server is doing some kind of object creation
+     * that the other side depends on, and that thread prematurely
+     * exits, you may experience a hang.  The test harness will
+     * terminate all hung threads after its timeout has expired,
+     * currently 3 minutes by default, but you might try to be
+     * smart about it....
+     */
+
+    /*
+     * Define the server side of the test.
+     *
+     * If the server prematurely exits, serverReady will be set to true
+     * to avoid infinite hangs.
+     */
+    private void doServerSide() throws Exception {
+        SSLServerSocketFactory sslssf =
+            (SSLServerSocketFactory)SSLServerSocketFactory.getDefault();
+        try (SSLServerSocket sslServerSocket =
+                (SSLServerSocket)sslssf.createServerSocket(serverPort)) {
+
+            serverPort = sslServerSocket.getLocalPort();
+
+            /*
+             * Signal Client, we're ready for his connect.
+             */
+            serverReady = true;
+
+            /*
+             * Accept connections
+             */
+            try (SSLSocket sslSocket = (SSLSocket)sslServerSocket.accept()) {
+                InputStream sslIS = sslSocket.getInputStream();
+                OutputStream sslOS = sslSocket.getOutputStream();
+                BufferedReader br =
+                        new BufferedReader(new InputStreamReader(sslIS));
+                PrintStream ps = new PrintStream(sslOS);
+
+                // process HTTP POST request from client
+                System.out.println("status line: " + br.readLine());
+                String msg = null;
+                while ((msg = br.readLine()) != null && msg.length() > 0);
+
+                msg = br.readLine();
+                if (msg.equals(postMsg)) {
+                    ps.println("HTTP/1.1 200 OK\n\n");
+                } else {
+                    ps.println("HTTP/1.1 500 Not OK\n\n");
+                }
+                ps.flush();
+
+                ExtendedSSLSession session =
+                        (ExtendedSSLSession)sslSocket.getSession();
+                if (session.getRequestedServerNames().isEmpty()) {
+                    throw new Exception("No expected Server Name Indication");
+                }
+
+                // close the socket
+                while (!closeReady) {
+                    Thread.sleep(50);
+                }
+            }
+        }
+    }
+
+    /*
+     * Define the client side of the test.
+     *
+     * If the server prematurely exits, serverReady will be set to true
+     * to avoid infinite hangs.
+     */
+    private void doClientSide() throws Exception {
+        /*
+         * Wait for server to get started.
+         */
+        while (!serverReady) {
+            Thread.sleep(50);
+        }
+
+        // Send HTTP POST request to server
+        URL url = new URL("https://" + hostname + ":" + serverPort);
+
+        HttpsURLConnection.setDefaultHostnameVerifier(new NameVerifier());
+        HttpsURLConnection http = (HttpsURLConnection)url.openConnection();
+        http.setDoOutput(true);
+
+        http.setRequestMethod("POST");
+        PrintStream ps = new PrintStream(http.getOutputStream());
+        try {
+            ps.println(postMsg);
+            ps.flush();
+            if (http.getResponseCode() != 200) {
+                throw new RuntimeException("test Failed");
+            }
+        } finally {
+            ps.close();
+            http.disconnect();
+            closeReady = true;
+        }
+    }
+
+    private static class NameVerifier implements HostnameVerifier {
+        public boolean verify(String hostname, SSLSession session) {
+            return true;
+        }
+    }
+
+    /*
+     * =============================================================
+     * The remainder is just support stuff
+     */
+
+    // use any free port by default
+    private volatile int serverPort = 0;
+
+    private volatile Exception serverException = null;
+    private volatile Exception clientException = null;
+
+    public static void main(String[] args) throws Exception {
+        String keyFilename =
+            System.getProperty("test.src", "./") + "/" + pathToStores +
+                "/" + keyStoreFile;
+        String trustFilename =
+            System.getProperty("test.src", "./") + "/" + pathToStores +
+                "/" + trustStoreFile;
+
+        System.setProperty("javax.net.ssl.keyStore", keyFilename);
+        System.setProperty("javax.net.ssl.keyStorePassword", passwd);
+        System.setProperty("javax.net.ssl.trustStore", trustFilename);
+        System.setProperty("javax.net.ssl.trustStorePassword", passwd);
+
+        if (debug) {
+            System.setProperty("javax.net.debug", "all");
+        }
+
+        try {
+            hostname = InetAddress.getLocalHost().getCanonicalHostName();
+        } catch (UnknownHostException uhe) {
+            System.out.println(
+                "Ignore the test as the local hostname cannot be determined");
+
+            return;
+        }
+
+        System.out.println(
+                "The fully qualified domain name of the local host is " +
+                hostname);
+        // Ignore the test if the hostname does not sound like a domain name.
+        if ((hostname == null) || hostname.isEmpty() ||
+                hostname.startsWith("localhost") ||
+                Character.isDigit(hostname.charAt(hostname.length() - 1))) {
+
+            System.out.println("Ignore the test as the local hostname " +
+                    "cannot be determined as fully qualified domain name");
+
+            return;
+        }
+
+        /*
+         * Start the tests.
+         */
+        new ImpactOnSNI();
+    }
+
+    private Thread clientThread = null;
+    private Thread serverThread = null;
+
+    /*
+     * Primary constructor, used to drive remainder of the test.
+     *
+     * Fork off the other side, then do your work.
+     */
+    ImpactOnSNI() throws Exception {
+        Exception startException = null;
+        try {
+            if (separateServerThread) {
+                startServer(true);
+                startClient(false);
+            } else {
+                startClient(true);
+                startServer(false);
+            }
+        } catch (Exception e) {
+            startException = e;
+        }
+
+        /*
+         * Wait for other side to close down.
+         */
+        if (separateServerThread) {
+            if (serverThread != null) {
+                serverThread.join();
+            }
+        } else {
+            if (clientThread != null) {
+                clientThread.join();
+            }
+        }
+
+        /*
+         * When we get here, the test is pretty much over.
+         * Which side threw the error?
+         */
+        Exception local;
+        Exception remote;
+
+        if (separateServerThread) {
+            remote = serverException;
+            local = clientException;
+        } else {
+            remote = clientException;
+            local = serverException;
+        }
+
+        Exception exception = null;
+
+        /*
+         * Check various exception conditions.
+         */
+        if ((local != null) && (remote != null)) {
+            // If both failed, return the curthread's exception.
+            local.initCause(remote);
+            exception = local;
+        } else if (local != null) {
+            exception = local;
+        } else if (remote != null) {
+            exception = remote;
+        } else if (startException != null) {
+            exception = startException;
+        }
+
+        /*
+         * If there was an exception *AND* a startException,
+         * output it.
+         */
+        if (exception != null) {
+            if (exception != startException && startException != null) {
+                exception.addSuppressed(startException);
+            }
+            throw exception;
+        }
+
+        // Fall-through: no exception to throw!
+    }
+
+    private void startServer(boolean newThread) throws Exception {
+        if (newThread) {
+            serverThread = new Thread() {
+                @Override
+                public void run() {
+                    try {
+                        doServerSide();
+                    } catch (Exception e) {
+                        /*
+                         * Our server thread just died.
+                         *
+                         * Release the client, if not active already...
+                         */
+                        System.err.println("Server died...");
+                        serverReady = true;
+                        serverException = e;
+                    }
+                }
+            };
+            serverThread.start();
+        } else {
+            try {
+                doServerSide();
+            } catch (Exception e) {
+                serverException = e;
+            } finally {
+                serverReady = true;
+            }
+        }
+    }
+
+    private void startClient(boolean newThread) throws Exception {
+        if (newThread) {
+            clientThread = new Thread() {
+                @Override
+                public void run() {
+                    try {
+                        doClientSide();
+                    } catch (Exception e) {
+                        /*
+                         * Our client thread just died.
+                         */
+                        System.err.println("Client died...");
+                        clientException = e;
+                    }
+                }
+            };
+            clientThread.start();
+        } else {
+            try {
+                doClientSide();
+            } catch (Exception e) {
+                clientException = e;
+            }
+        }
+    }
+}