Improve exception message of XmppConnectionStressTest

XEP-0060 prohibits publishing a request that contains an item to a node that
is both 'notification-only' and 'transient' (section 7.1.3.6)

In commit 8ed872ca63 the existing pubsub publication
test was modified (to resolve a different issue) to operate on a node that's both
'notification-only' and 'transient'. This resulted in a test that should return
an error, even though the test implementation didn't expect one.

This commit explicitly verifies that publishing an item to such a node causes
an error to be returned. A new test is added that verifies that publishing an
event notification does succeed.

config/checkstyle.xml

@@ -6,6 +6,11 @@
 	<module name="SuppressionFilter">
 		<property name="file" value="config/suppressions.xml"/>
 	</module>
+	<module name="SuppressWithPlainTextCommentFilter">
+		<property name="offCommentFormat" value="CHECKSTYLE\:OFF\:(\w+)"/>
+		<property name="onCommentFormat" value="CHECKSTYLE\:ON\:(\w+)"/>
+		<property name="checkFormat" value="$1"/>
+	</module>
 	<module name="Header">
 		<property name="headerFile" value="config/${checkstyleLicenseHeader}.txt"/>
 		<property name="ignoreLines" value="3"/>
@@ -61,6 +66,14 @@
 		<property name="format" value="^\s*//[^\s]"/>
 		<property name="message" value="Comment start ('//') followed by non-space character. You would not continue after a punctuation without a space, would you?"/>
 	</module>
+	<!-- Check for synchronized keyword on Manager's static
+	     getInstanceFor() method. Note that if XMPPConnection is every
+	     replaced with something else, then we need to change it here
+	     too. -->
+	<module name="RegexpSingleline">
+		<property name="format" value="^\s*public(?!.*synchronized).*getInstanceFor\(XMPPConnection.*$"/>
+		<property name="message" value="getInstanceFor() should be synchronized"/>
+	</module>
 	<module name="JavadocPackage"/>
 	<module name="TreeWalker">
 		<module name="SuppressionCommentFilter"/>

documentation/extensions/index.md

@@ -103,6 +103,7 @@ Experimental Smack Extensions and currently supported XEPs of smack-experimental
 | [OMEMO Multi End Message and Object Encryption](omemo.md) | [XEP-0384](https://xmpp.org/extensions/xep-0384.html)  | n/a       | Encrypt messages using OMEMO encryption (currently only with smack-omemo-signal -> GPLv3). |
 | [Consistent Color Generation](consistent_colors.md)       | [XEP-0392](https://xmpp.org/extensions/xep-0392.html)  | 0.4.0     | Generate consistent colors for identifiers like usernames to provide a consistent user experience. |
 | [Message Markup](messagemarkup.md)                        | [XEP-0394](https://xmpp.org/extensions/xep-0394.html)  | 0.1.0     | Style message bodies while keeping body and markup information separated. |
+| DNS Queries over XMPP (DoX)                               | [XEP-0418](https://xmpp.org/extensions/xep-0418.html)  | 0.1.0     | Send DNS queries and responses over XMPP. |
 
 Unofficial XMPP Extensions
 --------------------------

documentation/processing.md

@@ -20,7 +20,7 @@ and a stanza listener:
 ```
 // Create a stanza filter to listen for new messages from a particular
 // user. We use an AndFilter to combine two other filters._
-StanzaFilter filter = new AndFilter(StanzaTypeFilter.Message, FromMatchesFilter.create("mary@jivesoftware.com"));
+StanzaFilter filter = new AndFilter(StanzaTypeFilter.MESSAGE, FromMatchesFilter.create("mary@jivesoftware.com"));
 // Assume we've created an XMPPConnection named "connection".
 
 // First, register a stanza collector using the filter we created.

settings.gradle

@@ -12,6 +12,7 @@ include 'smack-core',
 		'smack-debug-slf4j',
 		'smack-resolver-dnsjava',
 		'smack-resolver-minidns',
+		'smack-resolver-minidns-dox',
 		'smack-resolver-javax',
 		'smack-sasl-javax',
 		'smack-sasl-provided',

smack-android/src/main/java/org/jivesoftware/smack/util/stringencoder/android/AndroidBase64Encoder.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,18 +42,17 @@ public final class AndroidBase64Encoder implements org.jivesoftware.smack.util.s
     }
 
     @Override
-    public byte[] decode(byte[] input, int offset, int len) {
-        return Base64.decode(input, offset, len, 0);
+    public String encodeToString(byte[] input) {
+        return Base64.encodeToString(input, BASE64_ENCODER_FLAGS);
     }
 
     @Override
-    public String encodeToString(byte[] input, int offset, int len) {
-        return Base64.encodeToString(input, offset, len, BASE64_ENCODER_FLAGS);
+    public String encodeToStringWithoutPadding(byte[] input) {
+        return Base64.encodeToString(input, BASE64_ENCODER_FLAGS | Base64.NO_PADDING);
     }
 
     @Override
-    public byte[] encode(byte[] input, int offset, int len) {
-        return Base64.encode(input, offset, len, BASE64_ENCODER_FLAGS);
+    public byte[] encode(byte[] input) {
+        return Base64.encode(input, BASE64_ENCODER_FLAGS);
     }
-
 }

smack-core/build.gradle

@@ -20,7 +20,6 @@ dependencies {
 	testCompile "org.powermock:powermock-module-junit4-rule:$powerMockVersion"
 	testCompile "org.powermock:powermock-api-mockito2:$powerMockVersion"
 	testCompile 'com.jamesmurty.utils:java-xmlbuilder:1.2'
-	testCompile 'net.iharder:base64:2.3.8'
 }
 
 class CreateFileTask extends DefaultTask {

smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java

@@ -41,6 +41,7 @@ import java.util.LinkedHashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.CopyOnWriteArraySet;
@@ -343,6 +344,17 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
 
     protected final AsyncButOrdered<StanzaListener> inOrderListeners = new AsyncButOrdered<>();
 
+    /**
+     * An executor which uses {@link #asyncGoLimited(Runnable)} to limit the number of asynchronously processed runnables
+     * per connection.
+     */
+    private final Executor limitedExcutor = new Executor() {
+        @Override
+        public void execute(Runnable runnable) {
+            asyncGoLimited(runnable);
+        }
+    };
+
     /**
      * The used host to establish the connection to
      */
@@ -1336,7 +1348,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
                         executorService = ASYNC_BUT_ORDERED.asExecutorFor(this);
                         break;
                     case async:
-                        executorService = CACHED_EXECUTOR_SERVICE;
+                        executorService = limitedExcutor;
                         break;
                     }
                     final IQRequestHandler finalIqRequestHandler = iqRequestHandler;
@@ -1353,7 +1365,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
                                 return;
                             }
 
-                            assert (response.getType() == IQ.Type.result || response.getType() == IQ.Type.error);
+                            assert response.isResponseIQ();
 
                             response.setTo(iqRequest.getFrom());
                             response.setStanzaId(iqRequest.getStanzaId());
@@ -1379,7 +1391,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         final Collection<StanzaListener> listenersToNotify = new LinkedList<>();
         extractMatchingListeners(packet, asyncRecvListeners, listenersToNotify);
         for (final StanzaListener listener : listenersToNotify) {
-            asyncGo(new Runnable() {
+            asyncGoLimited(new Runnable() {
                 @Override
                 public void run() {
                     try {
@@ -1875,6 +1887,75 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         return getClass().getSimpleName() + '[' + localEndpointString + "] (" + getConnectionCounter() + ')';
     }
 
+    /**
+     * A queue of deferred runnables that where not executed immediately because {@link #currentAsyncRunnables} reached
+     * {@link #maxAsyncRunnables}. Note that we use a {@code LinkedList} in order to avoid space blowups in case the
+     * list ever becomes very big and shrinks again.
+     */
+    private final Queue<Runnable> deferredAsyncRunnables = new LinkedList<>();
+
+    private int deferredAsyncRunnablesCount;
+
+    private int deferredAsyncRunnablesCountPrevious;
+
+    private int maxAsyncRunnables = SmackConfiguration.getDefaultConcurrencyLevelLimit();
+
+    private int currentAsyncRunnables;
+
+    protected void asyncGoLimited(final Runnable runnable) {
+        Runnable wrappedRunnable = new Runnable() {
+            @Override
+            public void run() {
+                runnable.run();
+
+                synchronized (deferredAsyncRunnables) {
+                    Runnable defferredRunnable = deferredAsyncRunnables.poll();
+                    if (defferredRunnable == null) {
+                        currentAsyncRunnables--;
+                    } else {
+                        deferredAsyncRunnablesCount--;
+                        asyncGo(defferredRunnable);
+                    }
+                }
+            }
+        };
+
+        synchronized (deferredAsyncRunnables) {
+            if (currentAsyncRunnables < maxAsyncRunnables) {
+                currentAsyncRunnables++;
+                asyncGo(wrappedRunnable);
+            } else {
+                deferredAsyncRunnablesCount++;
+                deferredAsyncRunnables.add(wrappedRunnable);
+            }
+
+            final int HIGH_WATERMARK = 100;
+            final int INFORM_WATERMARK = 20;
+
+            final int deferredAsyncRunnablesCount = this.deferredAsyncRunnablesCount;
+
+            if (deferredAsyncRunnablesCount >= HIGH_WATERMARK
+                    && deferredAsyncRunnablesCountPrevious < HIGH_WATERMARK) {
+                LOGGER.log(Level.WARNING, "High watermark of " + HIGH_WATERMARK + " simultaneous executing runnables reached");
+            } else if (deferredAsyncRunnablesCount >= INFORM_WATERMARK
+                    && deferredAsyncRunnablesCountPrevious < INFORM_WATERMARK) {
+                LOGGER.log(Level.INFO, INFORM_WATERMARK + " simultaneous executing runnables reached");
+            }
+
+            deferredAsyncRunnablesCountPrevious = deferredAsyncRunnablesCount;
+        }
+    }
+
+    public void setMaxAsyncOperations(int maxAsyncOperations) {
+        if (maxAsyncOperations < 1) {
+            throw new IllegalArgumentException("Max async operations must be greater than 0");
+        }
+
+        synchronized (deferredAsyncRunnables) {
+            maxAsyncRunnables = maxAsyncOperations;
+        }
+    }
+
     protected static void asyncGo(Runnable runnable) {
         CACHED_EXECUTOR_SERVICE.execute(runnable);
     }

smack-core/src/main/java/org/jivesoftware/smack/AsyncButOrdered.java

@@ -55,6 +55,16 @@ public class AsyncButOrdered<K> {
 
     private final Map<K, Boolean> threadActiveMap = new WeakHashMap<>();
 
+    private final Executor executor;
+
+    public AsyncButOrdered() {
+        this(null);
+    }
+
+    public AsyncButOrdered(Executor executor) {
+        this.executor = executor;
+    }
+
     /**
      * Invoke the given {@link Runnable} asynchronous but ordered in respect to the given key.
      *
@@ -86,7 +96,11 @@ public class AsyncButOrdered<K> {
             if (newHandler) {
                 Handler handler = new Handler(keyQueue, key);
                 threadActiveMap.put(key, true);
+                if (executor == null) {
                     AbstractXMPPConnection.asyncGo(handler);
+                } else {
+                    executor.execute(handler);
+                }
             }
         }
 

smack-core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2003-2007 Jive Software, 2017-2018 Florian Schmaus.
+ * Copyright 2003-2007 Jive Software, 2017-2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,9 +49,29 @@ import org.minidns.dnsname.DnsName;
 import org.minidns.util.InetAddressUtil;
 
 /**
- * Configuration to use while establishing the connection to the server.
+ * The connection configuration used for XMPP client-to-server connections. A well configured XMPP service will
+ * typically only require you to provide two parameters: The XMPP address, also known as the JID, of the user and the
+ * password. All other configuration parameters could ideally be determined automatically by Smack. Hence it is often
+ * enough to call {@link Builder#setXmppAddressAndPassword(CharSequence, String)}.
+ * <p>
+ * Technically there are typically at least two parameters required: Some kind of credentials for authentication. And
+ * the XMPP service domain. The credentials often consists of a username and password use for the SASL authentication.
+ * But there are also other authentication mechanisms, like client side certificates, which do not require a particular
+ * username and password.
+ * </p>
+ * <p>
+ * There are some misconceptions about XMPP client-to-server parameters: The first is that the username used for
+ * authentication will be equal to the localpart of the bound XMPP address after authentication. While this is usually
+ * true, it is not required. Technically the username used for authentication and the resulting XMPP address are
+ * completely independent from each other. The second common misconception steers from the terms "XMPP host" and "XMPP
+ * service domain": An XMPP service host is a system which hosts one or multiple XMPP domains. The "XMPP service domain"
+ * will be usually the domainpart of the bound JID. This domain is used to verify the remote endpoint, typically using
+ * TLS. This third misconception is that the XMPP service domain is required to become the domainpart of the bound JID.
+ * Again, while this is very common to be true, it is not strictly required.
+ * </p>
  *
  * @author Gaston Dombiak
+ * @author Florian Schmaus
  */
 public abstract class ConnectionConfiguration {
 
@@ -534,6 +554,39 @@ public abstract class ConnectionConfiguration {
             }
         }
 
+        /**
+         * Convenience method to configure the username, password and XMPP service domain.
+         *
+         * @param jid the XMPP address of the user.
+         * @param password the password of the user.
+         * @return a reference to this builder.
+         * @throws XmppStringprepException in case the XMPP address is not valid.
+         * @see #setXmppAddressAndPassword(EntityBareJid, String)
+         * @since 4.4.0
+         */
+        public B setXmppAddressAndPassword(CharSequence jid, String password) throws XmppStringprepException {
+            return setXmppAddressAndPassword(JidCreate.entityBareFrom(jid), password);
+        }
+
+        /**
+         * Convenience method to configure the username, password and XMPP service domain. The localpart of the provided
+         * JID is used as username and the domanipart is used as XMPP service domain.
+         * <p>
+         * Please note that this does and can not configure the client XMPP address. XMPP services are not required to
+         * assign bound JIDs where the localpart matches the username and the domainpart matches the verified domainpart.
+         * Although most services will follow that pattern.
+         * </p>
+         *
+         * @param jid
+         * @param password
+         * @return a reference to this builder.
+         * @since 4.4.0
+         */
+        public B setXmppAddressAndPassword(EntityBareJid jid, String password) {
+            setUsernameAndPassword(jid.getLocalpart(), password);
+            return setXmppDomain(jid.asDomainBareJid());
+        }
+
         /**
          * Set the XMPP entities username and password.
          * <p>

smack-core/src/main/java/org/jivesoftware/smack/SmackConfiguration.java

@@ -365,4 +365,19 @@ public final class SmackConfiguration {
     public static void setUnknownIqRequestReplyMode(UnknownIqRequestReplyMode unknownIqRequestReplyMode) {
         SmackConfiguration.unknownIqRequestReplyMode = Objects.requireNonNull(unknownIqRequestReplyMode, "Must set mode");
     }
+
+    private static final int defaultConcurrencyLevelLimit;
+
+    static {
+        int availableProcessors = Runtime.getRuntime().availableProcessors();
+        if (availableProcessors < 8) {
+            defaultConcurrencyLevelLimit = 8;
+        } else {
+            defaultConcurrencyLevelLimit = (int) (availableProcessors * 1.1);
+        }
+    }
+
+    public static int getDefaultConcurrencyLevelLimit() {
+        return defaultConcurrencyLevelLimit;
+    }
 }

smack-core/src/main/java/org/jivesoftware/smack/XMPPConnection.java

@@ -70,6 +70,27 @@ import org.jxmpp.jid.EntityFullJid;
  * disconnected and then connected again. Listeners of the XMPPConnection will be retained across
  * connections.
  * </p>
+ * <h2>Incoming Stanza Listeners</h2>
+ * Most callbacks (listeners, handlers, …) than you can add to a connection come in three different variants:
+ * <ul>
+ * <li>standard</li>
+ * <li>async (asynchronous)</li>
+ * <li>sync (synchronous)</li>
+ * </ul>
+ * <p>
+ * Standard callbacks are invoked concurrently, but it is ensured that the same callback is never run concurrently.
+ * The callback's identity is used as key for that. The events delivered to the callback preserve the order of the
+ * causing events of the connection.
+ * </p>
+ * <p>
+ * Asynchronous callbacks are run decoupled from the connections main event loop. Hence a callback triggered by
+ * stanza B may (appear to) invoked before a callback triggered by stanza A, even though stanza A arrived before B.
+ * </p>
+ * <p>
+ * Synchronous callbacks are run synchronous to the main event loop of a connection. Hence they are invoked in the
+ * exact order of how events happen there, most importantly the arrival order of incoming stanzas. You should only
+ * use synchronous callbacks in rare situations.
+ * </p>
  *
  * @author Matt Tucker
  * @author Guenther Niess

smack-core/src/main/java/org/jivesoftware/smack/debugger/ConsoleDebugger.java

@@ -16,12 +16,11 @@
  */
 package org.jivesoftware.smack.debugger;
 
-import java.io.PrintWriter;
-import java.io.StringWriter;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
 import org.jivesoftware.smack.XMPPConnection;
+import org.jivesoftware.smack.util.ExceptionUtil;
 
 /**
  * Very simple debugger that prints to the console (stdout) the sent and received stanzas. Use
@@ -55,12 +54,8 @@ public class ConsoleDebugger extends AbstractDebugger {
 
     @Override
     protected void log(String logMessage, Throwable throwable) {
-        StringWriter sw = new StringWriter();
-        PrintWriter pw = new PrintWriter(sw);
-        // CHECKSTYLE:OFF
-        throwable.printStackTrace(pw);
-        // CHECKSTYLE:ON
-        log(logMessage + sw);
+        String stacktrace = ExceptionUtil.getStackTrace(throwable);
+        log(logMessage + '\n' + stacktrace);
     }
 
     public static final class Factory implements SmackDebuggerFactory {

smack-core/src/main/java/org/jivesoftware/smack/packet/AbstractError.java

@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 
+import org.jivesoftware.smack.util.ExceptionUtil;
 import org.jivesoftware.smack.util.Objects;
 import org.jivesoftware.smack.util.PacketUtil;
 import org.jivesoftware.smack.util.XmlStringBuilder;
@@ -150,6 +151,17 @@ public class AbstractError {
             return getThis();
         }
 
+        public B setDescriptiveEnText(String descriptiveEnText, Exception exception) {
+            StringBuilder sb = new StringBuilder(512);
+            sb.append(descriptiveEnText)
+                .append('\n');
+
+            String stacktrace = ExceptionUtil.getStackTrace(exception);
+            sb.append(stacktrace);
+
+            return setDescriptiveEnText(sb.toString());
+        }
+
         public B setTextNamespace(String textNamespace) {
             this.textNamespace = textNamespace;
             return getThis();

smack-core/src/main/java/org/jivesoftware/smack/packet/IQ.java

@@ -105,6 +105,16 @@ public abstract class IQ extends Stanza {
         }
     }
 
+    /**
+     * Return true if this IQ is a request, i.e. an IQ of type {@link Type#result} or {@link Type#error}.
+     *
+     * @return true if IQ type is 'result' or 'error', false otherwise.
+     * @since 4.4
+     */
+    public boolean isResponseIQ() {
+        return !isRequestIQ();
+    }
+
     public final String getChildElementName() {
         return childElementName;
     }
@@ -287,7 +297,7 @@ public abstract class IQ extends Stanza {
      * @return a new {@link Type#error IQ.Type.error} IQ based on the originating IQ.
      */
     public static ErrorIQ createErrorResponse(final IQ request, final StanzaError.Builder error) {
-        if (!(request.getType() == Type.get || request.getType() == Type.set)) {
+        if (!request.isRequestIQ()) {
             throw new IllegalArgumentException(
                     "IQ must be of type 'set' or 'get'. Original IQ: " + request.toXML());
         }

smack-core/src/main/java/org/jivesoftware/smack/util/ExceptionUtil.java

@@ -0,0 +1,38 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+public class ExceptionUtil {
+
+    public static String getStackTrace(Throwable throwable) {
+        StringWriter stringWriter = new StringWriter();
+        PrintWriter printWriter = new PrintWriter(stringWriter);
+
+        // CHECKSTYLE:OFF
+        throwable.printStackTrace(printWriter);
+        // CHECKSTYLE:ON
+
+        printWriter.flush();
+
+        StringBuffer stringBuffer = stringWriter.getBuffer();
+        return stringBuffer.toString();
+    }
+
+}

smack-core/src/main/java/org/jivesoftware/smack/util/RandomUtil.java

@@ -0,0 +1,50 @@
+/**
+ *
+ * Copyright 2003-2007 Jive Software, 2016-2019 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+import java.security.SecureRandom;
+import java.util.Random;
+
+public class RandomUtil {
+
+    static final ThreadLocal<SecureRandom> SECURE_RANDOM = new ThreadLocal<SecureRandom>() {
+        @Override
+        protected SecureRandom initialValue() {
+            return new SecureRandom();
+        }
+    };
+
+    /**
+     * Pseudo-random number generator object for use with randomString().
+     * The Random class is not considered to be cryptographically secure, so
+     * only use these random Strings for low to medium security applications.
+     */
+    static final ThreadLocal<Random> RANDOM = new ThreadLocal<Random>() {
+        @Override
+        protected Random initialValue() {
+            return new Random();
+        }
+    };
+
+    public static int nextSecureRandomInt(int bound) {
+        return SECURE_RANDOM.get().nextInt(bound);
+    }
+
+    public static int nextSecureRandomInt() {
+        return SECURE_RANDOM.get().nextInt();
+    }
+}

smack-core/src/main/java/org/jivesoftware/smack/util/StringUtils.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2003-2007 Jive Software, 2016-2018 Florian Schmaus.
+ * Copyright 2003-2007 Jive Software, 2016-2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,6 @@
 package org.jivesoftware.smack.util;
 
 import java.io.UnsupportedEncodingException;
-import java.security.SecureRandom;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Random;
@@ -253,18 +252,6 @@ public class StringUtils {
         }
     }
 
-    /**
-     * Pseudo-random number generator object for use with randomString().
-     * The Random class is not considered to be cryptographically secure, so
-     * only use these random Strings for low to medium security applications.
-     */
-    private static final ThreadLocal<Random> randGen = new ThreadLocal<Random>() {
-        @Override
-        protected Random initialValue() {
-            return new Random();
-        }
-    };
-
     /**
      * Array of numbers and letters of mixed case. Numbers appear in the list
      * twice so that there is a more equal chance that a number will be picked.
@@ -288,23 +275,16 @@ public class StringUtils {
      * @return a random String of numbers and letters of the specified length.
      */
     public static String insecureRandomString(int length) {
-        return randomString(length, randGen.get());
+        return randomString(length, RandomUtil.RANDOM.get());
     }
 
-    private static final ThreadLocal<SecureRandom> SECURE_RANDOM = new ThreadLocal<SecureRandom>() {
-        @Override
-        protected SecureRandom initialValue() {
-            return new SecureRandom();
-        }
-    };
-
     public static String randomString(final int length) {
-        return randomString(length, SECURE_RANDOM.get());
+        return randomString(length, RandomUtil.SECURE_RANDOM.get());
     }
 
     public static String randomString(final int length, Random random) {
-        if (length < 1) {
-            return null;
+        if (length == 0) {
+            return "";
         }
 
         byte[] randomBytes = new byte[length];

smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014-2015 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,29 +39,19 @@ public class Base64 {
     }
 
     public static final String encodeToString(byte[] input) {
-        byte[] bytes = encode(input);
-        try {
-            return new String(bytes, StringUtils.USASCII);
-        } catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        return base64encoder.encodeToString(input);
     }
 
     public static final String encodeToString(byte[] input, int offset, int len) {
-        byte[] bytes = encode(input, offset, len);
-        try {
-            return new String(bytes, StringUtils.USASCII);
-        } catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
+        return encodeToString(slice(input, offset, len));
     }
+
+    public static final String encodeToStringWithoutPadding(byte[] input) {
+        return base64encoder.encodeToStringWithoutPadding(input);
     }
 
     public static final byte[] encode(byte[] input) {
-        return encode(input, 0, input.length);
-    }
-
-    public static final byte[] encode(byte[] input, int offset, int len) {
-        return base64encoder.encode(input, offset, len);
+        return base64encoder.encode(input);
     }
 
     public static final String decodeToString(String string) {
@@ -73,34 +63,43 @@ public class Base64 {
         }
     }
 
-    public static final String decodeToString(byte[] input, int offset, int len) {
-        byte[] bytes = decode(input, offset, len);
-        try {
-            return new String(bytes, StringUtils.UTF8);
-        } catch (UnsupportedEncodingException e) {
-            throw new IllegalStateException("UTF-8 not supported", e);
-        }
-    }
-
+    // TODO: We really should not mask the IllegalArgumentException. But some unit test depend on this behavior, like
+    // ibb.packet.DataPacketExtension.shouldReturnNullIfDataIsInvalid().
     public static final byte[] decode(String string) {
+        try {
             return base64encoder.decode(string);
+        } catch (IllegalArgumentException e) {
+            return null;
+        }
     }
 
     public static final byte[] decode(byte[] input) {
-        return base64encoder.decode(input, 0, input.length);
+        String string;
+        try {
+            string = new String(input, StringUtils.USASCII);
+        } catch (UnsupportedEncodingException e) {
+            throw new AssertionError(e);
+        }
+        return decode(string);
     }
 
-    public static final byte[] decode(byte[] input, int offset, int len) {
-        return base64encoder.decode(input, offset, len);
+    private static byte[] slice(byte[] input, int offset, int len) {
+        if (offset == 0 && len == input.length) {
+            return input;
+        }
+
+        byte[] res = new byte[len];
+        System.arraycopy(input, offset, res, 0, len);
+        return res;
     }
 
     public interface Encoder {
         byte[] decode(String string);
 
-        byte[] decode(byte[] input, int offset, int len);
+        String encodeToString(byte[] input);
 
-        String encodeToString(byte[] input, int offset, int len);
+        String encodeToStringWithoutPadding(byte[] input);
 
-        byte[] encode(byte[] input, int offset, int len);
+        byte[] encode(byte[] input);
     }
 }

smack-core/src/test/java/org/jivesoftware/smack/DummyConnection.java

@@ -64,6 +64,11 @@ public class DummyConnection extends AbstractXMPPConnection {
         this(getDummyConfigurationBuilder().build());
     }
 
+    public DummyConnection(CharSequence username, String password, String serviceName) throws XmppStringprepException {
+        this(getDummyConfigurationBuilder().setUsernameAndPassword(username, password).setXmppDomain(
+                                        JidCreate.domainBareFrom(serviceName)).build());
+    }
+
     private EntityFullJid getUserJid() {
         try {
             return JidCreate.entityFullFrom(config.getUsername()

smack-core/src/test/java/org/jivesoftware/smack/test/util/SmackTestSuite.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,14 +16,10 @@
  */
 package org.jivesoftware.smack.test.util;
 
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
+import java.util.Base64;
 
-import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.stringencoder.Base64.Encoder;
 
-import net.iharder.Base64;
-
 /**
  * The SmackTestSuite takes care of initializing Smack for the unit tests. For example the Base64
  * encoder is configured.
@@ -35,53 +31,24 @@ public class SmackTestSuite {
 
             @Override
             public byte[] decode(String string) {
-                try {
-                    return Base64.decode(string);
-                }
-                catch (IllegalArgumentException e) {
-                    // Expected by e.g. the unit test.
-                    // " Base64-encoded string must have at least four characters, but length specified was 1",
-                    // should not cause an exception, but instead null should be returned. Maybe
-                    // this should be changed in a later Smack release, so that the actual exception
-                    // is handled.
-                    return null;
-                }
-                catch (IOException e) {
-                    throw new IllegalStateException(e);
-                }
+                return Base64.getDecoder().decode(string);
             }
 
             @Override
-            public byte[] decode(byte[] input, int offset, int len) {
-                try {
-                    return Base64.decode(input, offset, len, 0);
-                }
-                catch (IllegalArgumentException e) {
-                    // Expected by e.g. the unit test.
-                    // " Base64-encoded string must have at least four characters, but length specified was 1",
-                    // should not cause an exception, but instead null should be returned. Maybe
-                    // this should be changed in a later Smack release, so that the actual exception
-                    // is handled.
-                    return null;
-                } catch (IOException e) {
-                    throw new IllegalStateException(e);
-                }
+            public String encodeToString(byte[] input) {
+                return Base64.getEncoder().encodeToString(input);
             }
 
             @Override
-            public String encodeToString(byte[] input, int offset, int len) {
-                return Base64.encodeBytes(input, offset, len);
+            public String encodeToStringWithoutPadding(byte[] input) {
+                return Base64.getEncoder().withoutPadding().encodeToString(input);
             }
 
             @Override
-            public byte[] encode(byte[] input, int offset, int len) {
-                String string = encodeToString(input, offset, len);
-                try {
-                    return string.getBytes(StringUtils.USASCII);
-                } catch (UnsupportedEncodingException e) {
-                    throw new AssertionError(e);
-                }
+            public byte[] encode(byte[] input) {
+                return Base64.getEncoder().encode(input);
             }
+
         });
     }
 }

smack-core/src/test/java/org/jivesoftware/smack/util/MemoryLeakTestUtil.java

@@ -0,0 +1,140 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import java.lang.ref.PhantomReference;
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Function;
+import java.util.logging.Logger;
+
+import org.jivesoftware.smack.DummyConnection;
+import org.jivesoftware.smack.Manager;
+
+import org.jxmpp.stringprep.XmppStringprepException;
+
+/**
+ * Utility class to test for memory leaks caused by Smack.
+ * <p>
+ * Note that this test is based on the assumption that it is possible to trigger a full garbage collection run, which is
+ * not the case. See also this
+ * <a href="https://stackoverflow.com/questions/1481178/how-to-force-garbage-collection-in-java">stackoverflow
+ * question</a>. Hence the {@link #triggerGarbageCollection()} method defined in this class is not portable and depends
+ * on implementation depended Java Virtual Machine behavior.
+ * </p>
+ *
+ * @see <a href="https://issues.igniterealtime.org/browse/SMACK-383">SMACK-383 Jira Issue</a>
+ */
+public class MemoryLeakTestUtil {
+
+    private static final Logger LOGGER = Logger.getLogger(MemoryLeakTestUtil.class.getName());
+
+    public static <M extends Manager> void noResourceLeakTest(Function<DummyConnection, M> managerSupplier)
+            throws XmppStringprepException, IllegalArgumentException, InterruptedException {
+        final int numConnections = 10;
+
+        ReferenceQueue<DummyConnection> connectionsReferenceQueue = new ReferenceQueue<>();
+        ReferenceQueue<Manager> managerReferenceQueue = new ReferenceQueue<>();
+
+        // Those two sets ensure that we hold a strong reference to the created PhantomReferences until the end of the
+        // test.
+        @SuppressWarnings("ModifiedButNotUsed")
+        Set<PhantomReference<DummyConnection>> connectionsPhantomReferences = new HashSet<>();
+        @SuppressWarnings("ModifiedButNotUsed")
+        Set<PhantomReference<Manager>> managersPhantomReferences = new HashSet<>();
+
+        List<DummyConnection> connections = new ArrayList<>(numConnections);
+        for (int i = 0; i < numConnections; i++) {
+            DummyConnection connection = new DummyConnection("foo" + i, "bar", "baz");
+
+            PhantomReference<DummyConnection> connectionPhantomReference = new PhantomReference<>(connection, connectionsReferenceQueue);
+            connectionsPhantomReferences.add(connectionPhantomReference);
+
+            Manager manager = managerSupplier.apply(connection);
+            PhantomReference<Manager> managerPhantomReference = new PhantomReference<Manager>(manager, managerReferenceQueue);
+            managersPhantomReferences.add(managerPhantomReference);
+
+            connections.add(connection);
+        }
+
+        // Clear the only references to the created connections.
+        connections = null;
+
+        triggerGarbageCollection();
+
+        // Now the connections should have been gc'ed, but not managers not yet.
+        assertReferencesQueueSize(connectionsReferenceQueue, numConnections);
+        assertReferencesQueueIsEmpty(managerReferenceQueue);
+
+        // We new create another connection and explicitly a new Manager. This will trigger the cleanup mechanism in the
+        // WeakHashMaps used by the Manager's iNSTANCE field. This should clean up all references to the Managers.
+        DummyConnection connection = new DummyConnection("last", "bar", "baz");
+        @SuppressWarnings("unused")
+        Manager manager = managerSupplier.apply(connection);
+
+        // The previous Managers should now be reclaimable by the garbage collector. First trigger a GC run.
+        triggerGarbageCollection();
+
+        // Now the Managers should have been freed and this means we should see their phantom references in the
+        // reference queue.
+        assertReferencesQueueSize(managerReferenceQueue, numConnections);
+    }
+
+    private static void assertReferencesQueueSize(ReferenceQueue<?> referenceQueue, int expectedSize) throws IllegalArgumentException, InterruptedException {
+        final int timeout = 60000;
+        for (int itemsRemoved = 0; itemsRemoved < expectedSize; ++itemsRemoved) {
+            Reference<?> reference = referenceQueue.remove(timeout);
+            assertNotNull("No reference found after " + timeout + "ms", reference);
+            reference.clear();
+        }
+
+        Reference<?> reference = referenceQueue.poll();
+        assertNull("Reference queue is not empty when it should be", reference);
+    }
+
+    private static void assertReferencesQueueIsEmpty(ReferenceQueue<?> referenceQueue) {
+        Reference<?> reference = referenceQueue.poll();
+        assertNull(reference);
+    }
+
+    private static void triggerGarbageCollection() {
+        Object object = new Object();
+        WeakReference<Object> weakReference = new WeakReference<>(object);
+        object = null;
+
+        int gcCalls = 0;
+        do {
+            if (gcCalls > 1000) {
+                throw new AssertionError("No observed gargabe collection after " + gcCalls + " calls of System.gc()");
+            }
+            System.gc();
+            gcCalls++;
+        } while (weakReference.get() != null);
+
+        // Note that this is no guarantee that a *full* garbage collection run has been made, which is what we actually
+        // need here in order to prevent false negatives.
+        LOGGER.finer("Observed garbage collection after " + gcCalls + " calls of System.gc()");
+    }
+}

smack-core/src/test/java/org/jivesoftware/smack/util/StringUtilsTest.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2003-2007 Jive Software.
+ * Copyright 2003-2007 Jive Software, 2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -88,13 +88,7 @@ public class StringUtilsTest  {
 
     @Test
     public void testRandomString() {
-        // Boundary test
-        String result = StringUtils.randomString(-1);
-        assertNull(result);
-
-        // Zero length string test
-        result = StringUtils.randomString(0);
-        assertNull(result);
+        String result;
 
         // Test various lengths - make sure the same length is returned
         result = StringUtils.randomString(4);
@@ -104,4 +98,17 @@ public class StringUtilsTest  {
         result = StringUtils.randomString(128);
         assertTrue(result.length() == 128);
     }
+
+    @Test(expected = NegativeArraySizeException.class)
+    public void testNegativeArraySizeException() {
+        // Boundary test
+        StringUtils.randomString(-1);
+    }
+
+    @Test
+    public void testZeroLengthRandomString() {
+        // Zero length string test
+        String result = StringUtils.randomString(0);
+        assertEquals("", result);
+    }
 }

smack-experimental/build.gradle

@@ -11,5 +11,5 @@ dependencies {
 	testCompile project(path: ":smack-core", configuration: "archives")
 	testCompile project(path: ":smack-extensions", configuration: "testRuntime")
 
-	compile "org.bouncycastle:bcprov-jdk15on:1.57"
+	compile "org.bouncycastle:bcprov-jdk15on:$bouncyCastleVersion"
 }

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/DnsOverXmppManager.java

@@ -0,0 +1,169 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.dox;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.WeakHashMap;
+import java.util.logging.Logger;
+
+import org.jivesoftware.smack.Manager;
+import org.jivesoftware.smack.SmackException.NoResponseException;
+import org.jivesoftware.smack.SmackException.NotConnectedException;
+import org.jivesoftware.smack.XMPPConnection;
+import org.jivesoftware.smack.XMPPException.XMPPErrorException;
+import org.jivesoftware.smack.iqrequest.AbstractIqRequestHandler;
+import org.jivesoftware.smack.iqrequest.IQRequestHandler.Mode;
+import org.jivesoftware.smack.packet.IQ;
+import org.jivesoftware.smack.packet.StanzaError;
+import org.jivesoftware.smack.packet.StanzaError.Condition;
+import org.jivesoftware.smack.packet.StanzaError.Type;
+import org.jivesoftware.smack.util.RandomUtil;
+import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
+import org.jivesoftware.smackx.dox.element.DnsIq;
+
+import org.jxmpp.jid.Jid;
+import org.minidns.dnsmessage.DnsMessage;
+import org.minidns.dnsmessage.Question;
+
+public final class DnsOverXmppManager extends Manager {
+
+    private static final Logger LOGGER = Logger.getLogger(DnsOverXmppManager.class.getName());
+
+    private static final Map<XMPPConnection, DnsOverXmppManager> INSTANCES = new WeakHashMap<>();
+
+    public static synchronized DnsOverXmppManager getInstanceFor(XMPPConnection connection) {
+        DnsOverXmppManager manager = INSTANCES.get(connection);
+        if (manager == null) {
+            manager = new DnsOverXmppManager(connection);
+            INSTANCES.put(connection, manager);
+        }
+        return manager;
+    }
+
+    private static final String NAMESPACE = DnsIq.NAMESPACE;
+
+    private static DnsOverXmppResolver defaultResolver;
+
+    public void setDefaultDnsOverXmppResolver(DnsOverXmppResolver resolver) {
+        defaultResolver = resolver;
+    }
+
+    private final ServiceDiscoveryManager serviceDiscoveryManager;
+
+    private DnsOverXmppResolver resolver = defaultResolver;
+
+    private boolean enabled;
+
+    private final AbstractIqRequestHandler dnsIqRequestHandler = new AbstractIqRequestHandler(
+            DnsIq.ELEMENT, DnsIq.NAMESPACE, IQ.Type.get, Mode.async) {
+
+        @Override
+        public IQ handleIQRequest(IQ iqRequest) {
+            DnsOverXmppResolver resolver = DnsOverXmppManager.this.resolver;
+            if (resolver == null) {
+                LOGGER.info("Resolver was null while attempting to handle " + iqRequest);
+                return null;
+            }
+
+            DnsIq dnsIqRequest = (DnsIq) iqRequest;
+            DnsMessage query = dnsIqRequest.getDnsMessage();
+
+            DnsMessage response;
+            try {
+                response = resolver.resolve(query);
+            } catch (IOException exception) {
+                StanzaError.Builder errorBuilder = StanzaError.getBuilder()
+                        .setType(Type.CANCEL)
+                        .setCondition(Condition.internal_server_error)
+                        .setDescriptiveEnText("Exception while resolving your DNS query", exception)
+                        ;
+
+                IQ errorResponse = IQ.createErrorResponse(iqRequest, errorBuilder);
+                return errorResponse;
+            }
+
+            if (query.id != response.id) {
+                // The ID may not match because the resolver returned a cached result.
+                response = response.asBuilder().setId(query.id).build();
+            }
+
+            DnsIq dnsIqResult = new DnsIq(response);
+            dnsIqResult.setType(IQ.Type.result);
+            return dnsIqResult;
+        }
+    };
+
+    private DnsOverXmppManager(XMPPConnection connection) {
+        super(connection);
+        this.serviceDiscoveryManager = ServiceDiscoveryManager.getInstanceFor(connection);
+    }
+
+    public synchronized void setDnsOverXmppResolver(DnsOverXmppResolver resolver) {
+        this.resolver = resolver;
+        if (resolver == null) {
+            disable();
+        }
+    }
+
+    public synchronized void enable() {
+        if (enabled) return;
+
+        if (resolver == null) {
+            throw new IllegalStateException("No DnsOverXmppResolver configured");
+        }
+
+        XMPPConnection connection = connection();
+        if (connection == null) return;
+
+        connection.registerIQRequestHandler(dnsIqRequestHandler);
+        serviceDiscoveryManager.addFeature(NAMESPACE);
+    }
+
+    public synchronized void disable() {
+        if (!enabled) return;
+
+        XMPPConnection connection = connection();
+        if (connection == null) return;
+
+        serviceDiscoveryManager.removeFeature(NAMESPACE);
+        connection.unregisterIQRequestHandler(dnsIqRequestHandler);
+    }
+
+    public boolean isSupported(Jid jid)
+            throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        return serviceDiscoveryManager.supportsFeature(jid, NAMESPACE);
+    }
+
+    public DnsMessage query(Jid jid, Question question) throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        DnsMessage queryMessage = DnsMessage.builder()
+                .addQuestion(question)
+                .setId(RandomUtil.nextSecureRandomInt())
+                .setRecursionDesired(true)
+                .build();
+        return query(jid, queryMessage);
+    }
+
+    public DnsMessage query(Jid jid, DnsMessage query)
+            throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        DnsIq queryIq = new DnsIq(query, jid);
+
+        DnsIq responseIq = connection().sendIqRequestAndWaitForResponse(queryIq);
+
+        return responseIq.getDnsMessage();
+    }
+}

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/DnsOverXmppResolver.java

@@ -0,0 +1,27 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.dox;
+
+import java.io.IOException;
+
+import org.minidns.dnsmessage.DnsMessage;
+
+public interface DnsOverXmppResolver {
+
+    DnsMessage resolve(DnsMessage query) throws IOException;
+
+}

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/element/DnsIq.java

@@ -0,0 +1,80 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.dox.element;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+import org.jivesoftware.smack.packet.IQ;
+import org.jivesoftware.smack.util.stringencoder.Base64;
+
+import org.jxmpp.jid.Jid;
+import org.minidns.dnsmessage.DnsMessage;
+
+public class DnsIq extends IQ {
+
+    public static final String ELEMENT = "dns";
+    public static final String NAMESPACE = "urn:xmpp:dox:0";
+
+    private final DnsMessage dnsMessage;
+
+    private String base64DnsMessage;
+
+    public DnsIq(String base64DnsMessage) throws IOException {
+        this(Base64.decode(base64DnsMessage));
+        this.base64DnsMessage = base64DnsMessage;
+    }
+
+    public DnsIq(byte[] dnsMessage) throws IOException {
+        this(new DnsMessage(dnsMessage));
+    }
+
+    public DnsIq(DnsMessage dnsQuery, Jid to) {
+        this(dnsQuery);
+        setTo(to);
+        setType(Type.get);
+    }
+
+    public DnsIq(DnsMessage dnsMessage) {
+        super(ELEMENT, NAMESPACE);
+        this.dnsMessage = dnsMessage;
+    }
+
+    public DnsMessage getDnsMessage() {
+        return dnsMessage;
+    }
+
+    @SuppressWarnings("ByteBufferBackingArray")
+    public String getDnsMessageBase64Encoded() {
+        if (base64DnsMessage == null) {
+            ByteBuffer byteBuffer = dnsMessage.getInByteBuffer();
+            byte[] bytes = byteBuffer.array();
+            base64DnsMessage = Base64.encodeToStringWithoutPadding(bytes);
+        }
+        return base64DnsMessage;
+    }
+
+    @Override
+    protected IQChildElementXmlStringBuilder getIQChildElementBuilder(IQChildElementXmlStringBuilder xml) {
+        xml.rightAngleBracket();
+
+        xml.escape(getDnsMessageBase64Encoded());
+
+        return xml;
+    }
+
+}

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/element/package-info.java

@@ -0,0 +1,21 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * XEP-0418: DNS Queries over XMPP (DoX) XML providers.
+ */
+package org.jivesoftware.smackx.dox.element;

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/package-info.java

@@ -0,0 +1,21 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Smack's API for XEP-0418: DNS Queries over XMPP (Dox).
+ */
+package org.jivesoftware.smackx.dox;

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/provider/DnsIqProvider.java

@@ -0,0 +1,38 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.dox.provider;
+
+import java.io.IOException;
+
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.parsing.SmackParsingException;
+import org.jivesoftware.smack.provider.IQProvider;
+import org.jivesoftware.smackx.dox.element.DnsIq;
+
+import org.xmlpull.v1.XmlPullParser;
+import org.xmlpull.v1.XmlPullParserException;
+
+public class DnsIqProvider extends IQProvider<DnsIq> {
+
+    @Override
+    public DnsIq parse(XmlPullParser parser, int initialDepth, XmlEnvironment xmlEnvironment)
+            throws XmlPullParserException, IOException, SmackParsingException {
+        String base64DnsMessage = parser.nextText();
+        return new DnsIq(base64DnsMessage);
+    }
+
+}

smack-experimental/src/main/java/org/jivesoftware/smackx/dox/provider/package-info.java

@@ -0,0 +1,21 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * XEP-0418: DNS Queries over XMPP (DoX) XML providers.
+ */
+package org.jivesoftware.smackx.dox.provider;

smack-experimental/src/main/java/org/jivesoftware/smackx/hashes/HashManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2017 Paul Schaub
+ * Copyright © 2017 Paul Schaub, 2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,6 @@ import static org.jivesoftware.smackx.hashes.HashManager.ALGORITHM.SHA_512;
 
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import java.security.NoSuchProviderException;
 import java.security.Security;
 import java.util.Arrays;
 import java.util.Collections;
@@ -61,7 +60,6 @@ public final class HashManager extends Manager {
     static {
         Security.addProvider(new BouncyCastleProvider());
     }
-    public static final String PROVIDER = "BC";
 
     public static final String PREFIX_NS_ALGO = "urn:xmpp:hash-function-text-names:";
 
@@ -224,52 +222,52 @@ public final class HashManager extends Manager {
         try {
             switch (algorithm) {
                 case MD5:
-                    md = MessageDigest.getInstance("MD5", PROVIDER);
+                    md = MessageDigest.getInstance("MD5");
                     break;
                 case SHA_1:
-                    md = MessageDigest.getInstance("SHA-1", PROVIDER);
+                    md = MessageDigest.getInstance("SHA-1");
                     break;
                 case SHA_224:
-                    md = MessageDigest.getInstance("SHA-224", PROVIDER);
+                    md = MessageDigest.getInstance("SHA-224");
                     break;
                 case SHA_256:
-                    md = MessageDigest.getInstance("SHA-256", PROVIDER);
+                    md = MessageDigest.getInstance("SHA-256");
                     break;
                 case SHA_384:
-                    md = MessageDigest.getInstance("SHA-384", PROVIDER);
+                    md = MessageDigest.getInstance("SHA-384");
                     break;
                 case SHA_512:
-                    md = MessageDigest.getInstance("SHA-512", PROVIDER);
+                    md = MessageDigest.getInstance("SHA-512");
                     break;
                 case SHA3_224:
-                    md = MessageDigest.getInstance("SHA3-224", PROVIDER);
+                    md = MessageDigest.getInstance("SHA3-224");
                     break;
                 case SHA3_256:
-                    md = MessageDigest.getInstance("SHA3-256", PROVIDER);
+                    md = MessageDigest.getInstance("SHA3-256");
                     break;
                 case SHA3_384:
-                    md = MessageDigest.getInstance("SHA3-384", PROVIDER);
+                    md = MessageDigest.getInstance("SHA3-384");
                     break;
                 case SHA3_512:
-                    md = MessageDigest.getInstance("SHA3-512", PROVIDER);
+                    md = MessageDigest.getInstance("SHA3-512");
                     break;
                 case BLAKE2B160:
-                    md = MessageDigest.getInstance("BLAKE2b-160", PROVIDER);
+                    md = MessageDigest.getInstance("BLAKE2b-160");
                     break;
                 case BLAKE2B256:
-                    md = MessageDigest.getInstance("BLAKE2b-256", PROVIDER);
+                    md = MessageDigest.getInstance("BLAKE2b-256");
                     break;
                 case BLAKE2B384:
-                    md = MessageDigest.getInstance("BLAKE2b-384", PROVIDER);
+                    md = MessageDigest.getInstance("BLAKE2b-384");
                     break;
                 case BLAKE2B512:
-                    md = MessageDigest.getInstance("BLAKE2b-512", PROVIDER);
+                    md = MessageDigest.getInstance("BLAKE2b-512");
                     break;
                 default:
                     throw new AssertionError("Invalid enum value: " + algorithm);
             }
             return md;
-        } catch (NoSuchAlgorithmException | NoSuchProviderException e) {
+        } catch (NoSuchAlgorithmException e) {
             throw new AssertionError(e);
         }
     }

smack-experimental/src/main/java/org/jivesoftware/smackx/jingle_filetransfer/JingleFileTransferManager.java

@@ -32,7 +32,7 @@ public final class JingleFileTransferManager extends Manager {
         super(connection);
     }
 
-    public static JingleFileTransferManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized JingleFileTransferManager getInstanceFor(XMPPConnection connection) {
         JingleFileTransferManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new JingleFileTransferManager(connection);

smack-experimental/src/main/java/org/jivesoftware/smackx/mam/MamManager.java

@@ -178,7 +178,9 @@ public final class MamManager extends Manager {
      * @param connection the XMPP connection to get the archive for.
      * @return the instance of MamManager.
      */
+    // CHECKSTYLE:OFF:RegexpSingleline
     public static MamManager getInstanceFor(XMPPConnection connection) {
+    // CHECKSTYLE:ON:RegexpSingleline
         return getInstanceFor(connection, (Jid) null);
     }
 

smack-experimental/src/main/java/org/jivesoftware/smackx/reference/ReferenceManager.java

@@ -51,7 +51,7 @@ public final class ReferenceManager extends Manager {
      * @param connection xmpp connection
      * @return reference manager instance
      */
-    public static ReferenceManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized ReferenceManager getInstanceFor(XMPPConnection connection) {
         ReferenceManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new ReferenceManager(connection);

smack-experimental/src/main/java/org/jivesoftware/smackx/sid/StableUniqueStanzaIdManager.java

@@ -78,7 +78,7 @@ public final class StableUniqueStanzaIdManager extends Manager {
      * @param connection xmpp-connection
      * @return manager instance for the connection
      */
-    public static StableUniqueStanzaIdManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized StableUniqueStanzaIdManager getInstanceFor(XMPPConnection connection) {
         StableUniqueStanzaIdManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new StableUniqueStanzaIdManager(connection);

smack-experimental/src/main/java/org/jivesoftware/smackx/spoiler/SpoilerManager.java

@@ -61,7 +61,7 @@ public final class SpoilerManager extends Manager {
      * @param connection xmpp connection
      * @return SpoilerManager
      */
-    public static SpoilerManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized SpoilerManager getInstanceFor(XMPPConnection connection) {
         SpoilerManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new SpoilerManager(connection);

smack-experimental/src/main/resources/org.jivesoftware.smack.experimental/experimental.providers

@@ -317,4 +317,11 @@
       <className>org.jivesoftware.smackx.message_markup.provider.MarkupElementProvider</className>
     </extensionProvider>
 
+    <!-- XEP-0418: DNS Queries over XMPP (DoX) -->
+    <iqProvider>
+      <elementName>dns</elementName>
+      <namespace>urn:xmpp:dox:0</namespace>
+      <className>org.jivesoftware.smackx.dox.provider.DnsIqProvider</className>
+    </iqProvider>
+
 </smackProviders>

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/ServiceDiscoveryManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2003-2007 Jive Software, 2018 Florian Schmaus.
+ * Copyright 2003-2007 Jive Software, 2018-2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -227,7 +227,7 @@ public final class ServiceDiscoveryManager extends Manager {
     /**
      * Returns the type of client that will be returned when asked for the client identity in a
      * disco request. The valid types are defined by the category client. Follow this link to learn
-     * the possible types: <a href="http://xmpp.org/registrar/disco-categories.html#client">Jabber::Registrar</a>.
+     * the possible types: <a href="https://xmpp.org/registrar/disco-categories.html">XMPP Registry for Service Discovery Identities</a>
      *
      * @return the type of client that will be returned when asked for the client identity in a
      *          disco request.
@@ -271,8 +271,8 @@ public final class ServiceDiscoveryManager extends Manager {
      */
     public Set<DiscoverInfo.Identity> getIdentities() {
         Set<Identity> res = new HashSet<>(identities);
-        // Add the default identity that must exist
-        res.add(defaultIdentity);
+        // Add the main identity that must exist
+        res.add(identity);
         return Collections.unmodifiableSet(res);
     }
 

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/packet/DiscoverInfo.java

@@ -263,7 +263,7 @@ public class DiscoverInfo extends IQ implements TypedCloneable<DiscoverInfo> {
      * Represents the identity of a given XMPP entity. An entity may have many identities but all
      * the identities SHOULD have the same name.<p>
      *
-     * Refer to <a href="http://www.jabber.org/registrar/disco-categories.html">Jabber::Registrar</a>
+     * Refer to <a href="https://xmpp.org/registrar/disco-categories.html">XMPP Registry for Service Discovery Identities</a>
      * in order to get the official registry of values for the <i>category</i> and <i>type</i>
      * attributes.
      *
@@ -327,7 +327,7 @@ public class DiscoverInfo extends IQ implements TypedCloneable<DiscoverInfo> {
 
         /**
          * Returns the entity's category. To get the official registry of values for the
-         * 'category' attribute refer to <a href="http://www.jabber.org/registrar/disco-categories.html">Jabber::Registrar</a>
+         * 'category' attribute refer to <a href="https://xmpp.org/registrar/disco-categories.html">XMPP Registry for Service Discovery Identities</a>.
          *
          * @return the entity's category.
          */
@@ -346,7 +346,7 @@ public class DiscoverInfo extends IQ implements TypedCloneable<DiscoverInfo> {
 
         /**
          * Returns the entity's type. To get the official registry of values for the
-         * 'type' attribute refer to <a href="http://www.jabber.org/registrar/disco-categories.html">Jabber::Registrar</a>
+         * 'type' attribute refer to <a href="https://xmpp.org/registrar/disco-categories.html">XMPP Registry for Service Discovery Identities</a>.
          *
          * @return the entity's type.
          */

smack-extensions/src/main/java/org/jivesoftware/smackx/geoloc/GeoLocationManager.java

@@ -124,7 +124,7 @@ public final class GeoLocationManager extends Manager {
 
     private LeafNode getNode()
             throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException, NotALeafNodeException {
-        return PubSubManager.getInstance(connection()).getOrCreateLeafNode(GeoLocation.NAMESPACE);
+        return PubSubManager.getInstanceFor(connection()).getOrCreateLeafNode(GeoLocation.NAMESPACE);
     }
 
 }

smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/JingleTransportMethodManager.java

@@ -48,7 +48,7 @@ public final class JingleTransportMethodManager extends Manager {
         super(connection);
     }
 
-    public static JingleTransportMethodManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized JingleTransportMethodManager getInstanceFor(XMPPConnection connection) {
         JingleTransportMethodManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new JingleTransportMethodManager(connection);

smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/transports/jingle_ibb/JingleIBBTransportManager.java

@@ -38,7 +38,7 @@ public final class JingleIBBTransportManager extends JingleTransportManager<Jing
         JingleContentProviderManager.addJingleContentTransportProvider(getNamespace(), new JingleIBBTransportProvider());
     }
 
-    public static JingleIBBTransportManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized JingleIBBTransportManager getInstanceFor(XMPPConnection connection) {
         JingleIBBTransportManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new JingleIBBTransportManager(connection);

smack-extensions/src/main/java/org/jivesoftware/smackx/jingle/transports/jingle_s5b/JingleS5BTransportManager.java

@@ -63,7 +63,7 @@ public final class JingleS5BTransportManager extends JingleTransportManager<Jing
         JingleContentProviderManager.addJingleContentTransportProvider(getNamespace(), new JingleS5BTransportProvider());
     }
 
-    public static JingleS5BTransportManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized JingleS5BTransportManager getInstanceFor(XMPPConnection connection) {
         JingleS5BTransportManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new JingleS5BTransportManager(connection);

smack-extensions/src/main/java/org/jivesoftware/smackx/mood/MoodManager.java

@@ -102,7 +102,7 @@ public final class MoodManager extends Manager {
         });
     }
 
-    public static MoodManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized MoodManager getInstanceFor(XMPPConnection connection) {
         MoodManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new MoodManager(connection);
@@ -147,7 +147,7 @@ public final class MoodManager extends Manager {
             throws SmackException.NotLoggedInException, InterruptedException, PubSubException.NotALeafNodeException,
             XMPPException.XMPPErrorException, SmackException.NotConnectedException, SmackException.NoResponseException {
         if (pubSubManager == null) {
-            pubSubManager = PubSubManager.getInstance(getAuthenticatedConnectionOrThrow(), connection().getUser().asBareJid());
+            pubSubManager = PubSubManager.getInstanceFor(getAuthenticatedConnectionOrThrow(), connection().getUser().asBareJid());
         }
 
         LeafNode node = pubSubManager.getOrCreateLeafNode(MOOD_NODE);

smack-extensions/src/main/java/org/jivesoftware/smackx/muc/MultiUserChatManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014-2018 Florian Schmaus
+ * Copyright © 2014-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -59,6 +59,7 @@ import org.jivesoftware.smackx.muc.packet.MUCUser;
 
 import org.jxmpp.jid.DomainBareJid;
 import org.jxmpp.jid.EntityBareJid;
+import org.jxmpp.jid.EntityFullJid;
 import org.jxmpp.jid.EntityJid;
 import org.jxmpp.jid.Jid;
 import org.jxmpp.jid.parts.Resourcepart;
@@ -304,7 +305,7 @@ public final class MultiUserChatManager extends Manager {
      * @throws NotConnectedException
      * @throws InterruptedException
      */
-    public List<EntityBareJid> getJoinedRooms(EntityJid user) throws NoResponseException, XMPPErrorException,
+    public List<EntityBareJid> getJoinedRooms(EntityFullJid user) throws NoResponseException, XMPPErrorException,
                     NotConnectedException, InterruptedException {
         // Send the disco packet to the user
         DiscoverItems result = serviceDiscoveryManager.discoverItems(user, DISCO_NODE);

smack-extensions/src/main/java/org/jivesoftware/smackx/pep/PepManager.java

@@ -120,7 +120,7 @@ public final class PepManager extends Manager {
         // TODO Add filter to check if from supports PubSub as per xep163 2 2.4
         connection.addSyncStanzaListener(packetListener, FROM_BARE_JID_WITH_EVENT_EXTENSION_FILTER);
 
-        pepPubSubManager = PubSubManager.getInstance(connection, null);
+        pepPubSubManager = PubSubManager.getInstanceFor(connection, null);
     }
 
     public PubSubManager getPepPubSubManager() {

smack-extensions/src/main/java/org/jivesoftware/smackx/pubsub/PubSubManager.java

@@ -88,7 +88,9 @@ public final class PubSubManager extends Manager {
      * @param connection
      * @return the default PubSub manager.
      */
-    public static PubSubManager getInstance(XMPPConnection connection) {
+    // CHECKSTYLE:OFF:RegexpSingleline
+    public static PubSubManager getInstanceFor(XMPPConnection connection) {
+    // CHECKSTYLE:ON:RegexpSingleline
         DomainBareJid pubSubService = null;
         if (connection.isAuthenticated()) {
             try {
@@ -110,7 +112,7 @@ public final class PubSubManager extends Manager {
                 throw new RuntimeException(e);
             }
         }
-        return getInstance(connection, pubSubService);
+        return getInstanceFor(connection, pubSubService);
     }
 
     /**
@@ -121,7 +123,9 @@ public final class PubSubManager extends Manager {
      * @param pubSubService the PubSub service, may be <code>null</code>.
      * @return a PubSub manager for the connection and service.
      */
-    public static PubSubManager getInstance(XMPPConnection connection, BareJid pubSubService) {
+    // CHECKSTYLE:OFF:RegexpSingleline
+    public static PubSubManager getInstanceFor(XMPPConnection connection, BareJid pubSubService) {
+    // CHECKSTYLE:ON:RegexpSingleline
         if (pubSubService != null && connection.isAuthenticated() && connection.getUser().asBareJid().equals(pubSubService)) {
             // PEP service.
             pubSubService = null;
@@ -147,6 +151,28 @@ public final class PubSubManager extends Manager {
         return pubSubManager;
     }
 
+    /**
+     * Deprecated.
+     *
+     * @deprecated use {@link #getInstanceFor(XMPPConnection)} instead.
+     */
+    @Deprecated
+    // TODO: Remove in Smack 4.5.
+    public static PubSubManager getInstance(XMPPConnection connection) {
+        return getInstanceFor(connection);
+    }
+
+    /**
+     * Deprecated.
+     *
+     * @deprecated use {@link #getInstanceFor(XMPPConnection, BareJid)} instead.
+     */
+    @Deprecated
+    // TODO: Remove in Smack 4.5.
+    public static PubSubManager getInstance(XMPPConnection connection, BareJid pubSubService) {
+        return getInstanceFor(connection, pubSubService);
+    }
+
     /**
      * Create a pubsub manager associated to the specified connection where
      * the pubsub requests require a specific to address for packets.

smack-extensions/src/test/java/org/jivesoftware/smackx/muc/MucMemoryLeakTest.java

@@ -0,0 +1,32 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.muc;
+
+import org.jivesoftware.smack.test.util.SmackTestSuite;
+import org.jivesoftware.smack.util.MemoryLeakTestUtil;
+
+import org.junit.Test;
+import org.jxmpp.stringprep.XmppStringprepException;
+
+public class MucMemoryLeakTest extends SmackTestSuite {
+
+    @Test
+    public void mucMemoryLeakTest() throws XmppStringprepException, IllegalArgumentException, InterruptedException {
+        MemoryLeakTestUtil.noResourceLeakTest((c) -> MultiUserChatManager.getInstanceFor(c));
+    }
+
+}

smack-im/src/main/java/org/jivesoftware/smack/roster/Roster.java

@@ -560,7 +560,8 @@ public final class Roster extends Manager {
     }
 
     /**
-     * Add a roster loaded listener.
+     * Add a roster loaded listener. Roster loaded listeners are invoked once the {@link Roster}
+     * was successfully loaded.
      *
      * @param rosterLoadedListener the listener to add.
      * @return true if the listener was not already added.
@@ -587,6 +588,20 @@ public final class Roster extends Manager {
         }
     }
 
+    /**
+     * Add a {@link PresenceEventListener}. Such a listener will be fired whenever certain
+     * presence events happen.<p>
+     * Among those events are:
+     * <ul>
+     * <li> 'available' presence received
+     * <li> 'unavailable' presence received
+     * <li> 'error' presence received
+     * <li> 'subscribed' presence received
+     * <li> 'unsubscribed' presence received
+     * </ul>
+     * @param presenceEventListener listener to add.
+     * @return true if the listener was not already added.
+     */
     public boolean addPresenceEventListener(PresenceEventListener presenceEventListener) {
         return presenceEventListeners.add(presenceEventListener);
     }
@@ -1516,7 +1531,29 @@ public final class Roster extends Manager {
             final Presence presence = (Presence) packet;
             final Jid from = presence.getFrom();
 
-            final BareJid key = from != null ? from.asBareJid() : null;
+            final BareJid key;
+            if (from != null) {
+                key = from.asBareJid();
+            } else {
+                XMPPConnection connection = connection();
+                if (connection == null) {
+                    LOGGER.finest("Connection was null while trying to handle exotic presence stanza: " + presence);
+                    return;
+                }
+                // Assume the presence come "from the users account on the server" since no from was set (RFC 6120 §
+                // 8.1.2.1 4.). Note that getUser() may return null, but should never return null in this case as where
+                // connected.
+                EntityFullJid myJid = connection.getUser();
+                if (myJid == null) {
+                    LOGGER.info(
+                            "Connection had no local address in Roster's presence listener."
+                            + " Possibly we received a presence without from before being authenticated."
+                            + " Presence: " + presence);
+                    return;
+                }
+                LOGGER.info("Exotic presence stanza without from received: " + presence);
+                key = myJid.asBareJid();
+            }
 
             asyncButOrdered.performAsyncButOrdered(key, new Runnable() {
                 @Override

smack-integration-test/src/main/java/org/igniterealtime/smack/XmppConnectionStressTest.java

@@ -151,19 +151,38 @@ public class XmppConnectionStressTest {
 
                     // Sanity check: All markers before must be true, all markers including the messageNumber marker must be false.
                     for (int i = 0; i < fromMarkers.length; i++) {
-                        if ((i < messageNumber && !fromMarkers[i])
-                                || (i >= messageNumber && fromMarkers[i])) {
-                            // TODO: Better exception.
-                            Exception exception = new Exception("out of order");
+                        final String inOrderViolation;
+                        if (i < messageNumber && !fromMarkers[i]) {
+                            // A previous message was missing.
+                            inOrderViolation = "not yet message #";
+                        } else if (i >= messageNumber && fromMarkers[i]) {
+                            // We already received a new message.
+                            // TODO: Can it ever happen that this is taken? Wouldn't we prior run into the "a previous
+                            // message is missing" case?
+                            inOrderViolation = "we already received a later (or the same) message #";
+                        } else {
+                            continue;
+                        }
+
+
+                        StringBuilder exceptionMessage = new StringBuilder();
+                        exceptionMessage.append("We received message #").append(messageNumber).append(" but ");
+                        exceptionMessage.append(inOrderViolation);
+                        exceptionMessage.append(i);
+                        exceptionMessage.append("\nMessage with id ").append(stanza.getStanzaId())
+                            .append(" from ").append(from)
+                            .append(" to ").append(stanza.getTo());
+
+                        Exception exception = new Exception(exceptionMessage.toString());
                         receiveExceptions.put(connection, exception);
                         // TODO: Current Smack design does not guarantee that the listener won't be invoked again.
                         // This is because the decission to invoke a sync listeners is done at a different place
                         // then invoking the listener.
                         connection.removeSyncStanzaListener(this);
                         receivedSemaphore.release();
+                        // TODO: Do not return here?
                         return;
                     }
-                    }
 
                     fromMarkers[messageNumber] = true;
 

smack-integration-test/src/main/java/org/igniterealtime/smack/inttest/XmppConnectionManager.java

@@ -240,6 +240,10 @@ public class XmppConnectionManager<DC extends AbstractXMPPConnection> {
         }
 
         connections.clear();
+
+        if (accountRegistrationConnection != null) {
+            accountRegistrationConnection.disconnect();
+        }
     }
 
 

smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoManagerSetupHelper.java

@@ -125,7 +125,7 @@ public class OmemoManagerSetupHelper {
     }
 
     public static void cleanUpPubSub(OmemoManager omemoManager) {
-        PubSubManager pm = PubSubManager.getInstance(omemoManager.getConnection(),omemoManager.getOwnJid());
+        PubSubManager pm = PubSubManager.getInstanceFor(omemoManager.getConnection(),omemoManager.getOwnJid());
         try {
             omemoManager.requestDeviceListUpdateFor(omemoManager.getOwnJid());
         } catch (SmackException.NotConnectedException | InterruptedException | SmackException.NoResponseException | PubSubException.NotALeafNodeException | XMPPException.XMPPErrorException e) {

smack-integration-test/src/main/java/org/jivesoftware/smackx/pubsub/PubSubIntegrationTest.java

@@ -17,12 +17,16 @@
 package org.jivesoftware.smackx.pubsub;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.util.List;
 
 import org.jivesoftware.smack.SmackException.NoResponseException;
 import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.XMPPException.XMPPErrorException;
+import org.jivesoftware.smack.packet.StanzaError;
 
 import org.igniterealtime.smack.inttest.AbstractSmackIntegrationTest;
 import org.igniterealtime.smack.inttest.SmackIntegrationTest;
@@ -42,33 +46,70 @@ public class PubSubIntegrationTest extends AbstractSmackIntegrationTest {
         if (pubSubService == null) {
             throw new TestNotPossibleException("No PubSub service found");
         }
-        pubSubManagerOne = PubSubManager.getInstance(conOne, pubSubService);
+        pubSubManagerOne = PubSubManager.getInstanceFor(conOne, pubSubService);
         if (!pubSubManagerOne.canCreateNodesAndPublishItems()) {
             throw new TestNotPossibleException("PubSub service does not allow node creation");
         }
     }
 
+    /**
+     * Asserts that an event notification (publication without item) can be published to
+     * a node that is both 'notification-only' as well as 'transient'.
+     */
     @SmackIntegrationTest
-    public void simplePubSubNodeTest() throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
-        final String nodename = "sinttest-simple-nodename-" + testRunId;
-        final String itemId = "sintest-simple-itemid-" + testRunId;
+    public void transientNotificationOnlyNodeWithoutItemTest() throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        final String nodename = "sinttest-transient-notificationonly-withoutitem-nodename-" + testRunId;
         ConfigureForm defaultConfiguration = pubSubManagerOne.getDefaultConfiguration();
         ConfigureForm config = new ConfigureForm(defaultConfiguration.createAnswerForm());
-        // Configure the node as "Notification-Only Node", which in turn means that
-        // items do not need payload, to prevent payload-required error responses when
-        // publishing the item.
+        // Configure the node as "Notification-Only Node".
         config.setDeliverPayloads(false);
-        // Set persistent_items to 'false' (was previously 'true') as workaround for ejabberd issue #2799
-        // (https://github.com/processone/ejabberd/issues/2799).
+        // Configure the node as "transient" (set persistent_items to 'false')
+        config.setPersistentItems(false);
+        Node node = pubSubManagerOne.createNode(nodename, config);
+        try {
+            LeafNode leafNode = (LeafNode) node;
+            leafNode.publish();
+            List<Item> items = leafNode.getItems();
+            assertTrue(items.isEmpty());
+        }
+        finally {
+            pubSubManagerOne.deleteNode(nodename);
+        }
+    }
+
+    /**
+     * Asserts that an error is returned when a publish request to a node that is both
+     * 'notification-only' as well as 'transient' contains an item element.
+     *
+     * <p>From XEP-0060 § 7.1.3.6:</p>
+     * <blockquote>
+     * If the event type is notification + transient and the publisher provides an item,
+     * the service MUST bounce the publication request with a &lt;bad-request/&gt; error
+     * and a pubsub-specific error condition of &lt;item-forbidden/&gt;.
+     * </blockquote>
+     *
+     * @see <a href="https://xmpp.org/extensions/xep-0060.html#publisher-publish-error-badrequest">
+     *     7.1.3.6 Request Does Not Match Configuration</a>
+     */
+    @SmackIntegrationTest
+    public void transientNotificationOnlyNodeWithItemTest() throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        final String nodename = "sinttest-transient-notificationonly-withitem-nodename-" + testRunId;
+        final String itemId = "sinttest-transient-notificationonly-withitem-itemid-" + testRunId;
+        ConfigureForm defaultConfiguration = pubSubManagerOne.getDefaultConfiguration();
+        ConfigureForm config = new ConfigureForm(defaultConfiguration.createAnswerForm());
+        // Configure the node as "Notification-Only Node".
+        config.setDeliverPayloads(false);
+        // Configure the node as "transient" (set persistent_items to 'false')
         config.setPersistentItems(false);
         Node node = pubSubManagerOne.createNode(nodename, config);
         try {
             LeafNode leafNode = (LeafNode) node;
             leafNode.publish(new Item(itemId));
-            List<Item> items = leafNode.getItems();
-            assertEquals(1, items.size());
-            Item item = items.get(0);
-            assertEquals(itemId, item.getId());
+            fail("An exception should have been thrown.");
+        }
+        catch (XMPPErrorException e) {
+            assertEquals(StanzaError.Type.MODIFY, e.getStanzaError().getType());
+            assertNotNull(e.getStanzaError().getExtension("item-forbidden", "http://jabber.org/protocol/pubsub#errors"));
         }
         finally {
             pubSubManagerOne.deleteNode(nodename);

smack-java7/src/main/java/org/jivesoftware/smack/util/stringencoder/java7/Java7Base64Encoder.java

@@ -16,9 +16,7 @@
  */
 package org.jivesoftware.smack.util.stringencoder.java7;
 
-import java.io.UnsupportedEncodingException;
-
-import org.jivesoftware.smack.util.StringUtils;
+import java.util.Base64;
 
 /**
  * A Base 64 encoding implementation.
@@ -28,10 +26,15 @@ public final class Java7Base64Encoder implements org.jivesoftware.smack.util.str
 
     private static final Java7Base64Encoder instance = new Java7Base64Encoder();
 
-    private static final int BASE64_ENCODER_FLAGS =  Base64.DONT_BREAK_LINES;
+    private final Base64.Encoder encoder;
+    private final Base64.Encoder encoderWithoutPadding;
+
+    private final Base64.Decoder decoder;
 
     private Java7Base64Encoder() {
-        // Use getInstance()
+        encoder = Base64.getEncoder();
+        encoderWithoutPadding = encoder.withoutPadding();
+        decoder = Base64.getDecoder();
     }
 
     public static Java7Base64Encoder getInstance() {
@@ -40,27 +43,21 @@ public final class Java7Base64Encoder implements org.jivesoftware.smack.util.str
 
     @Override
     public byte[] decode(String string) {
-        return Base64.decode(string);
+        return decoder.decode(string);
     }
 
     @Override
-    public byte[] decode(byte[] input, int offset, int len) {
-        return Base64.decode(input, offset, len, 0);
+    public String encodeToString(byte[] input) {
+        return encoder.encodeToString(input);
     }
 
     @Override
-    public String encodeToString(byte[] input, int offset, int len) {
-        return Base64.encodeBytes(input, offset, len, BASE64_ENCODER_FLAGS);
+    public String encodeToStringWithoutPadding(byte[] input) {
+        return encoderWithoutPadding.encodeToString(input);
     }
 
     @Override
-    public byte[] encode(byte[] input, int offset, int len) {
-        String string = encodeToString(input, offset, len);
-        try {
-            return string.getBytes(StringUtils.USASCII);
-        } catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
+    public byte[] encode(byte[] input) {
+        return encoder.encode(input);
     }
 }
-
-}

smack-java7/src/main/java/org/jivesoftware/smack/util/stringencoder/java7/Java7Base64UrlSafeEncoder.java

@@ -17,6 +17,7 @@
 package org.jivesoftware.smack.util.stringencoder.java7;
 
 import java.io.UnsupportedEncodingException;
+import java.util.Base64;
 
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.stringencoder.StringEncoder;
@@ -37,10 +38,12 @@ public final class Java7Base64UrlSafeEncoder implements StringEncoder<String> {
 
     private static final Java7Base64UrlSafeEncoder instance = new Java7Base64UrlSafeEncoder();
 
-    private static final int BASE64_ENCODER_FLAGS =  Base64.URL_SAFE | Base64.DONT_BREAK_LINES;
+    private final Base64.Encoder encoder;
+    private final Base64.Decoder decoder;
 
     private Java7Base64UrlSafeEncoder() {
-        // Use getInstance()
+        encoder = Base64.getUrlEncoder();
+        decoder = Base64.getUrlDecoder();
     }
 
     public static Java7Base64UrlSafeEncoder getInstance() {
@@ -56,13 +59,14 @@ public final class Java7Base64UrlSafeEncoder implements StringEncoder<String> {
         catch (UnsupportedEncodingException e) {
             throw new AssertionError(e);
         }
-        return Base64.encodeBytes(bytes, BASE64_ENCODER_FLAGS);
+        return encoder.encodeToString(bytes);
     }
 
     @Override
     public String decode(String s) {
+        byte[] bytes = decoder.decode(s);
         try {
-            return new String(Base64.decode(s, BASE64_ENCODER_FLAGS), StringUtils.UTF8);
+            return new String(bytes, StringUtils.UTF8);
         }
         catch (UnsupportedEncodingException e) {
             throw new AssertionError(e);

smack-jingle-old/src/main/java/org/jivesoftware/smackx/jingleold/JingleSession.java

@@ -620,7 +620,7 @@ public final class JingleSession extends JingleNegotiator implements MediaReceiv
      *            A XMPP connection
      * @return a Jingle session
      */
-    public static JingleSession getInstanceFor(XMPPConnection con) {
+    public static synchronized JingleSession getInstanceFor(XMPPConnection con) {
         if (con == null) {
             throw new IllegalArgumentException("XMPPConnection cannot be null");
         }

smack-omemo/build.gradle

@@ -3,7 +3,7 @@ dependencies {
 	compile project(":smack-extensions")
 	compile project(":smack-experimental")
 
-	compile "org.bouncycastle:bcprov-jdk15on:1.60"
+	compile "org.bouncycastle:bcprov-jdk15on:$bouncyCastleVersion"
 
 	testCompile project(path: ":smack-core", configuration: "testRuntime")
 }

smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoService.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Paul Schaub
+ * Copyright 2017 Paul Schaub, 2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,7 +23,6 @@ import java.io.UnsupportedEncodingException;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
-import java.security.NoSuchProviderException;
 import java.security.Security;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -308,7 +307,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
         try {
             builder = new OmemoMessageBuilder<>(userDevice, gullibleTrustCallback, getOmemoRatchet(manager),
                     messageKey, iv, null);
-        } catch (InvalidKeyException | InvalidAlgorithmParameterException | NoSuchPaddingException | BadPaddingException | UnsupportedEncodingException | NoSuchProviderException | IllegalBlockSizeException e) {
+        } catch (InvalidKeyException | InvalidAlgorithmParameterException | NoSuchPaddingException | BadPaddingException | UnsupportedEncodingException | IllegalBlockSizeException e) {
             throw new CryptoFailedException(e);
         }
 
@@ -370,7 +369,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
         try {
             builder = new OmemoMessageBuilder<>(
                     userDevice, manager.getTrustCallback(), getOmemoRatchet(managerGuard.get()), messageKey, iv, message);
-        } catch (UnsupportedEncodingException | BadPaddingException | IllegalBlockSizeException | NoSuchProviderException |
+        } catch (UnsupportedEncodingException | BadPaddingException | IllegalBlockSizeException |
                 NoSuchPaddingException | InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException e) {
             throw new CryptoFailedException(e);
         }
@@ -557,7 +556,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
             XMPPException.XMPPErrorException, PubSubException.NotALeafNodeException,
             PubSubException.NotAPubSubNodeException {
 
-        PubSubManager pm = PubSubManager.getInstance(connection, contactsDevice.getJid());
+        PubSubManager pm = PubSubManager.getInstanceFor(connection, contactsDevice.getJid());
         LeafNode node = pm.getLeafNode(contactsDevice.getBundleNodeName());
 
         if (node == null) {
@@ -585,7 +584,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
     static void publishBundle(XMPPConnection connection, OmemoDevice userDevice, OmemoBundleElement bundle)
             throws XMPPException.XMPPErrorException, SmackException.NotConnectedException, InterruptedException,
             SmackException.NoResponseException {
-        PubSubManager pm = PubSubManager.getInstance(connection, connection.getUser().asBareJid());
+        PubSubManager pm = PubSubManager.getInstanceFor(connection, connection.getUser().asBareJid());
         pm.tryToPublishAndPossibleAutoCreate(userDevice.getBundleNodeName(), new PayloadItem<>(bundle));
     }
 
@@ -607,7 +606,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
             SmackException.NotConnectedException, XMPPException.XMPPErrorException,
             PubSubException.NotAPubSubNodeException {
 
-        PubSubManager pm = PubSubManager.getInstance(connection, contact);
+        PubSubManager pm = PubSubManager.getInstanceFor(connection, contact);
         String nodeName = OmemoConstants.PEP_NODE_DEVICE_LIST;
         LeafNode node = pm.getLeafNode(nodeName);
 
@@ -637,7 +636,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
             throws InterruptedException, XMPPException.XMPPErrorException, SmackException.NotConnectedException,
             SmackException.NoResponseException {
 
-        PubSubManager.getInstance(connection, connection.getUser().asBareJid())
+        PubSubManager.getInstanceFor(connection, connection.getUser().asBareJid())
                 .tryToPublishAndPossibleAutoCreate(OmemoConstants.PEP_NODE_DEVICE_LIST, new PayloadItem<>(deviceList));
     }
 
@@ -786,33 +785,6 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
         processBundle(omemoManager, randomPreKeyBundle, contactsDevice);
     }
 
-    /**
-     * Build OMEMO sessions with all devices of the contact, we haven't had sessions with before.
-     * This method returns a set of OmemoDevices. This set contains all devices, with which we either had sessions
-     * before, plus those devices with which we just built sessions.
-     *
-     * @param connection authenticated XMPP connection.
-     * @param userDevice our OmemoDevice
-     * @param contact the BareJid of the contact with whom we want to build sessions with.
-     * @return set of devices with a session.
-     * @throws SmackException.NotConnectedException
-     * @throws InterruptedException
-     * @throws SmackException.NoResponseException
-     */
-    private Set<OmemoDevice> buildMissingSessionsWithContact(XMPPConnection connection,
-                                                             OmemoDevice userDevice,
-                                                             BareJid contact)
-            throws SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException {
-
-        OmemoCachedDeviceList contactsDeviceIds = getOmemoStoreBackend().loadCachedDeviceList(userDevice, contact);
-        Set<OmemoDevice> contactsDevices = new HashSet<>();
-        for (int deviceId : contactsDeviceIds.getActiveDevices()) {
-            contactsDevices.add(new OmemoDevice(contact, deviceId));
-        }
-
-        return buildMissingSessionsWithDevices(connection, userDevice, contactsDevices);
-    }
-
     /**
      * Build sessions with all devices from the set, we don't have a session with yet.
      * Return the set of all devices we have a session with afterwards.
@@ -854,34 +826,6 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
         return devicesWithSession;
     }
 
-    /**
-     * Build OMEMO sessions with all devices of the contacts, we haven't had sessions with before.
-     * This method returns a set of OmemoDevices. This set contains all devices, with which we either had sessions
-     * before, plus those devices with which we just built sessions.
-     *
-     * @param connection authenticated XMPP connection.
-     * @param userDevice our OmemoDevice
-     * @param contacts set of BareJids of contacts, we want to build sessions with.
-     * @return set of devices, we have sessions with.
-     * @throws SmackException.NotConnectedException
-     * @throws InterruptedException
-     * @throws SmackException.NoResponseException
-     */
-    private Set<OmemoDevice> buildMissingSessionsWithContacts(XMPPConnection connection,
-                                                              OmemoDevice userDevice,
-                                                              Set<BareJid> contacts)
-            throws SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException {
-
-        Set<OmemoDevice> devicesWithSessions = new HashSet<>();
-
-        for (BareJid contact : contacts) {
-            Set<OmemoDevice> devices = buildMissingSessionsWithContact(connection, userDevice, contact);
-            devicesWithSessions.addAll(devices);
-        }
-
-        return devicesWithSessions;
-    }
-
     /**
      * Return a set of all devices from the provided set, which trust level is undecided.
      * A device is also considered undecided, if its fingerprint cannot be loaded.
@@ -914,37 +858,6 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
         return undecidedDevices;
     }
 
-    /**
-     * Return a set of all devices from the provided set, which are untrusted.
-     * A device is also considered untrusted, if its fingerprint cannot be loaded.
-     *
-     * @param userDevice our own OmemoDevice
-     * @param trustCallback OmemoTrustCallback to query trust decisions from
-     * @param devices set of OmemoDevices
-     * @return set of OmemoDevices from devices, which contains all devices which are untrusted
-     */
-    private Set<OmemoDevice> getUntrustedDeviced(OmemoDevice userDevice, OmemoTrustCallback trustCallback, Set<OmemoDevice> devices) {
-        Set<OmemoDevice> untrustedDevices = new HashSet<>();
-
-        for (OmemoDevice device : devices) {
-
-            OmemoFingerprint fingerprint;
-            try {
-                fingerprint = getOmemoStoreBackend().getFingerprint(userDevice, device);
-            } catch (CorruptedOmemoKeyException | NoIdentityKeyException e) {
-                // TODO: Best solution?
-                untrustedDevices.add(device);
-                continue;
-            }
-
-            if (trustCallback.getTrust(device, fingerprint) == TrustState.untrusted) {
-                untrustedDevices.add(device);
-            }
-        }
-
-        return untrustedDevices;
-    }
-
     /**
      * Return true, if the OmemoManager of userDevice has a session with the contactsDevice.
      *

smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/CipherAndAuthTag.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Paul Schaub
+ * Copyright 2017 Paul Schaub, 2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,11 +18,9 @@ package org.jivesoftware.smackx.omemo.internal;
 
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.CIPHERMODE;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYTYPE;
-import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.PROVIDER;
 
 import java.security.InvalidAlgorithmParameterException;
 import java.security.NoSuchAlgorithmException;
-import java.security.NoSuchProviderException;
 import javax.crypto.Cipher;
 import javax.crypto.NoSuchPaddingException;
 import javax.crypto.spec.IvParameterSpec;
@@ -50,13 +48,13 @@ public class CipherAndAuthTag {
 
         Cipher cipher;
         try {
-            cipher = Cipher.getInstance(CIPHERMODE, PROVIDER);
+            cipher = Cipher.getInstance(CIPHERMODE);
             SecretKeySpec keySpec = new SecretKeySpec(key, KEYTYPE);
             IvParameterSpec ivSpec = new IvParameterSpec(iv);
             cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
         } catch (NoSuchAlgorithmException | java.security.InvalidKeyException |
                 InvalidAlgorithmParameterException |
-                NoSuchPaddingException | NoSuchProviderException e) {
+                NoSuchPaddingException e) {
             throw new CryptoFailedException(e);
         }
 

smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/util/OmemoConstants.java

@@ -58,6 +58,5 @@ public final class OmemoConstants {
         public static final String KEYTYPE = "AES";
         public static final int KEYLENGTH = 128;
         public static final String CIPHERMODE = "AES/GCM/NoPadding";
-        public static final String PROVIDER = "BC";
     }
 }

smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/util/OmemoMessageBuilder.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Paul Schaub
+ * Copyright 2017 Paul Schaub, 2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,6 @@ package org.jivesoftware.smackx.omemo.util;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.CIPHERMODE;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYLENGTH;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYTYPE;
-import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.PROVIDER;
 
 import java.io.UnsupportedEncodingException;
 import java.security.InvalidAlgorithmParameterException;
@@ -96,7 +95,6 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @throws NoSuchAlgorithmException
      * @throws IllegalBlockSizeException
      * @throws UnsupportedEncodingException
-     * @throws NoSuchProviderException
      * @throws InvalidAlgorithmParameterException
      */
     public OmemoMessageBuilder(OmemoDevice userDevice,
@@ -107,7 +105,7 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
                                String message)
             throws NoSuchPaddingException, BadPaddingException, InvalidKeyException, NoSuchAlgorithmException,
             IllegalBlockSizeException,
-            UnsupportedEncodingException, NoSuchProviderException, InvalidAlgorithmParameterException {
+            UnsupportedEncodingException, InvalidAlgorithmParameterException {
         this.userDevice = userDevice;
         this.trustCallback = callback;
         this.ratchet = ratchet;
@@ -130,7 +128,6 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @throws NoSuchAlgorithmException
      * @throws IllegalBlockSizeException
      * @throws UnsupportedEncodingException
-     * @throws NoSuchProviderException
      * @throws InvalidAlgorithmParameterException
      */
     public OmemoMessageBuilder(OmemoDevice userDevice,
@@ -138,7 +135,7 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
                                OmemoRatchet<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Sess, T_Addr, T_ECPub, T_Bundle, T_Ciph> ratchet,
                                String message)
             throws NoSuchPaddingException, BadPaddingException, InvalidKeyException, NoSuchAlgorithmException, IllegalBlockSizeException,
-            UnsupportedEncodingException, NoSuchProviderException, InvalidAlgorithmParameterException {
+            UnsupportedEncodingException, InvalidAlgorithmParameterException {
         this(userDevice, callback, ratchet, generateKey(KEYTYPE, KEYLENGTH), generateIv(), message);
     }
 
@@ -150,7 +147,6 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      *
      * @param message plaintext message
      * @throws NoSuchPaddingException
-     * @throws NoSuchAlgorithmException
      * @throws NoSuchProviderException
      * @throws InvalidAlgorithmParameterException
      * @throws InvalidKeyException
@@ -158,7 +154,7 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @throws BadPaddingException
      * @throws IllegalBlockSizeException
      */
-    private void setMessage(String message) throws NoSuchPaddingException, NoSuchAlgorithmException, NoSuchProviderException, InvalidAlgorithmParameterException, InvalidKeyException, UnsupportedEncodingException, BadPaddingException, IllegalBlockSizeException {
+    private void setMessage(String message) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, UnsupportedEncodingException, BadPaddingException, IllegalBlockSizeException {
         if (message == null) {
             return;
         }
@@ -166,7 +162,7 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
         // Encrypt message body
         SecretKey secretKey = new SecretKeySpec(messageKey, KEYTYPE);
         IvParameterSpec ivSpec = new IvParameterSpec(initializationVector);
-        Cipher cipher = Cipher.getInstance(CIPHERMODE, PROVIDER);
+        Cipher cipher = Cipher.getInstance(CIPHERMODE);
         cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivSpec);
 
         byte[] body;

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/OpenPgpManager.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Florian Schmaus, 2018 Paul Schaub.
+ * Copyright 2017-2019 Florian Schmaus, 2018 Paul Schaub.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -189,7 +189,7 @@ public final class OpenPgpManager extends Manager {
      * @param connection xmpp connection.
      * @return instance of the manager.
      */
-    public static OpenPgpManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized OpenPgpManager getInstanceFor(XMPPConnection connection) {
         OpenPgpManager manager = INSTANCES.get(connection);
         if (manager == null) {
             manager = new OpenPgpManager(connection);

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/CryptElement.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Florian Schmaus, 2018 Paul Schaub.
+ * Copyright 2017-2019 Florian Schmaus, 2018 Paul Schaub.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,11 +32,11 @@ public class CryptElement extends EncryptedOpenPgpContentElement {
 
     public static final String ELEMENT = "crypt";
 
-    public CryptElement(Set<Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
+    public CryptElement(Set<? extends Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
         super(to, rpad, timestamp, payload);
     }
 
-    public CryptElement(Set<Jid> to, List<ExtensionElement> payload) {
+    public CryptElement(Set<? extends Jid> to, List<ExtensionElement> payload) {
         super(to, payload);
     }
 

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/EncryptedOpenPgpContentElement.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Florian Schmaus, 2018 Paul Schaub.
+ * Copyright 2017-2019 Florian Schmaus, 2018 Paul Schaub.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,13 +16,13 @@
  */
 package org.jivesoftware.smackx.ox.element;
 
-import java.security.SecureRandom;
 import java.util.Date;
 import java.util.List;
 import java.util.Set;
 
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.util.Objects;
+import org.jivesoftware.smack.util.RandomUtil;
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
@@ -38,14 +38,14 @@ public abstract class EncryptedOpenPgpContentElement extends OpenPgpContentEleme
 
     private final String rpad;
 
-    protected EncryptedOpenPgpContentElement(Set<Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
+    protected EncryptedOpenPgpContentElement(Set<? extends Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
         super(Objects.requireNonNullNorEmpty(
                 to, "Encrypted OpenPGP content elements must have at least one 'to' attribute."),
                 timestamp, payload);
         this.rpad = Objects.requireNonNull(rpad);
     }
 
-    protected EncryptedOpenPgpContentElement(Set<Jid> to, List<ExtensionElement> payload) {
+    protected EncryptedOpenPgpContentElement(Set<? extends Jid> to, List<ExtensionElement> payload) {
         super(Objects.requireNonNullNorEmpty(
                 to, "Encrypted OpenPGP content elements must have at least one 'to' attribute."),
                 new Date(), payload);
@@ -53,8 +53,7 @@ public abstract class EncryptedOpenPgpContentElement extends OpenPgpContentEleme
     }
 
     private static String createRandomPadding() {
-        SecureRandom secRan = new SecureRandom();
-        int len = secRan.nextInt(256);
+        int len = RandomUtil.nextSecureRandomInt(256);
         return StringUtils.randomString(len);
     }
 

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/OpenPgpContentElement.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Florian Schmaus, 2018 Paul Schaub.
+ * Copyright 2017-2019 Florian Schmaus, 2018 Paul Schaub.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -48,13 +48,13 @@ public abstract class OpenPgpContentElement implements ExtensionElement {
     public static final String ATTR_STAMP = "stamp";
     public static final String ELEM_PAYLOAD = "payload";
 
-    private final Set<Jid> to;
+    private final Set<? extends Jid> to;
     private final Date timestamp;
     private final MultiMap<String, ExtensionElement> payload;
 
     private String timestampString;
 
-    protected OpenPgpContentElement(Set<Jid> to, Date timestamp, List<ExtensionElement> payload) {
+    protected OpenPgpContentElement(Set<? extends Jid> to, Date timestamp, List<ExtensionElement> payload) {
         this.to = to;
         this.timestamp = Objects.requireNonNull(timestamp);
         this.payload = new MultiMap<>();
@@ -68,7 +68,7 @@ public abstract class OpenPgpContentElement implements ExtensionElement {
      *
      * @return recipients.
      */
-    public final Set<Jid> getTo() {
+    public final Set<? extends Jid> getTo() {
         return to;
     }
 

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/SigncryptElement.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Florian Schmaus, 2018 Paul Schaub.
+ * Copyright 2017-2019 Florian Schmaus, 2018 Paul Schaub.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,11 +35,11 @@ public class SigncryptElement extends EncryptedOpenPgpContentElement {
 
     public static final String ELEMENT = "signcrypt";
 
-    public SigncryptElement(Set<Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
+    public SigncryptElement(Set<? extends Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
         super(to, rpad, timestamp, payload);
     }
 
-    public SigncryptElement(Set<Jid> to, List<ExtensionElement> payload) {
+    public SigncryptElement(Set<? extends Jid> to, List<ExtensionElement> payload) {
         super(to, payload);
     }
 

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/util/OpenPgpPubSubUtil.java

@@ -204,7 +204,7 @@ public class OpenPgpPubSubUtil {
     public static PublicKeysListElement fetchPubkeysList(XMPPConnection connection, BareJid contact)
             throws InterruptedException, XMPPException.XMPPErrorException, SmackException.NoResponseException,
             PubSubException.NotALeafNodeException, SmackException.NotConnectedException, PubSubException.NotAPubSubNodeException {
-        PubSubManager pm = PubSubManager.getInstance(connection, contact);
+        PubSubManager pm = PubSubManager.getInstanceFor(connection, contact);
 
         LeafNode node = getLeafNode(pm, PEP_NODE_PUBLIC_KEYS);
         List<PayloadItem<PublicKeysListElement>> list = node.getItems(1);
@@ -274,7 +274,7 @@ public class OpenPgpPubSubUtil {
     public static PubkeyElement fetchPubkey(XMPPConnection connection, BareJid contact, OpenPgpV4Fingerprint v4_fingerprint)
             throws InterruptedException, XMPPException.XMPPErrorException, PubSubException.NotAPubSubNodeException,
             PubSubException.NotALeafNodeException, SmackException.NotConnectedException, SmackException.NoResponseException {
-        PubSubManager pm = PubSubManager.getInstance(connection, contact);
+        PubSubManager pm = PubSubManager.getInstanceFor(connection, contact);
         String nodeName = PEP_NODE_PUBLIC_KEY(v4_fingerprint);
 
         LeafNode node = getLeafNode(pm, nodeName);

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox_im/OXInstantMessagingManager.java

@@ -135,7 +135,7 @@ public final class OXInstantMessagingManager extends Manager {
      * @param connection XMPP connection
      * @return manager instance
      */
-    public static OXInstantMessagingManager getInstanceFor(XMPPConnection connection) {
+    public static synchronized OXInstantMessagingManager getInstanceFor(XMPPConnection connection) {
         OXInstantMessagingManager manager = INSTANCES.get(connection);
 
         if (manager == null) {

smack-repl/build.gradle

@@ -14,6 +14,7 @@ dependencies {
 	compile project(':smack-bosh')
 	compile project(':smack-java7')
 	compile project(':smack-resolver-minidns')
+	compile project(':smack-resolver-minidns-dox')
     compile project(':smack-extensions')
 	compile project(':smack-experimental')
 	compile project(':smack-legacy')

smack-repl/src/main/java/org/igniterealtime/smack/smackrepl/DoX.java

@@ -0,0 +1,78 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.igniterealtime.smack.smackrepl;
+
+import java.io.IOException;
+
+import org.jivesoftware.smack.SmackConfiguration;
+import org.jivesoftware.smack.SmackException;
+import org.jivesoftware.smack.XMPPException;
+import org.jivesoftware.smack.debugger.ConsoleDebugger;
+import org.jivesoftware.smack.tcp.XMPPTCPConnection;
+import org.jivesoftware.smack.tcp.XMPPTCPConnectionConfiguration;
+import org.jivesoftware.smackx.dox.DnsOverXmppManager;
+import org.jivesoftware.smackx.dox.resolver.minidns.DnsOverXmppMiniDnsResolver;
+
+import org.jxmpp.jid.Jid;
+import org.jxmpp.jid.impl.JidCreate;
+import org.minidns.dnsmessage.DnsMessage;
+import org.minidns.dnsmessage.Question;
+import org.minidns.record.Record;
+
+public class DoX {
+
+    public static void main(String[] args) throws XMPPException, SmackException, IOException, InterruptedException {
+        SmackConfiguration.DEBUG = true;
+
+        XMPPTCPConnection connection = new XMPPTCPConnection(args[0], args[1]);
+        connection.setReplyTimeout(60000);
+
+        connection.connect().login();
+
+        DnsOverXmppManager dox = DnsOverXmppManager.getInstanceFor(connection);
+
+        Jid target = JidCreate.from("dns@moparisthebest.com/listener");
+        Question question = new Question("geekplace.eu", Record.TYPE.A);
+
+        DnsMessage response = dox.query(target, question);
+
+        // CHECKSTYLE:OFF
+        System.out.println(response);
+        // CHECKSTYLE:ON
+
+        connection.disconnect();
+    }
+
+    public static XMPPTCPConnection runDoxResolver(String jid, String password)
+            throws XMPPException, SmackException, IOException, InterruptedException {
+        XMPPTCPConnectionConfiguration config = XMPPTCPConnectionConfiguration.builder()
+                .setXmppAddressAndPassword(jid, password)
+                .setResource("dns")
+                .setDebuggerFactory(ConsoleDebugger.Factory.INSTANCE)
+                .build();
+        XMPPTCPConnection connection = new XMPPTCPConnection(config);
+
+        connection.connect().login();
+
+        DnsOverXmppManager dox = DnsOverXmppManager.getInstanceFor(connection);
+        dox.setDnsOverXmppResolver(DnsOverXmppMiniDnsResolver.INSTANCE);
+
+        dox.enable();
+
+        return connection;
+    }
+}

smack-resolver-minidns-dox/build.gradle

@@ -0,0 +1,8 @@
+description = """\
+DNS over XMPP (DoX) support using MiniDNS."""
+
+dependencies {
+	compile project(path: ':smack-resolver-minidns')
+	compile project(path: ':smack-experimental')
+	testCompile project(path: ":smack-core", configuration: "testRuntime")
+}

smack-resolver-minidns-dox/src/main/java/org/jivesoftware/smackx/dox/resolver/minidns/DnsOverXmppMiniDnsResolver.java

@@ -0,0 +1,57 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.dox.resolver.minidns;
+
+import java.io.IOException;
+
+import org.jivesoftware.smackx.dox.DnsOverXmppResolver;
+
+import org.minidns.DnsClient;
+import org.minidns.dnsmessage.DnsMessage;
+import org.minidns.dnsmessage.Question;
+import org.minidns.dnsqueryresult.DnsQueryResult;
+import org.minidns.dnssec.DnssecClient;
+import org.minidns.dnssec.DnssecQueryResult;
+
+public final class DnsOverXmppMiniDnsResolver implements DnsOverXmppResolver {
+
+    public static final DnsOverXmppMiniDnsResolver INSTANCE = new DnsOverXmppMiniDnsResolver(new DnsClient(), new DnssecClient());
+
+    private final DnsClient dnsClient;
+    private final DnssecClient dnssecClient;
+
+    DnsOverXmppMiniDnsResolver(DnsClient dnsClient, DnssecClient dnssecClient) {
+        this.dnsClient = dnsClient;
+        this.dnssecClient = dnssecClient;
+    }
+
+    @Override
+    public DnsMessage resolve(DnsMessage query) throws IOException {
+        Question question = query.getQuestion();
+
+        final DnsQueryResult dnsQueryResult;
+        if (query.isDnssecOk()) {
+            DnssecQueryResult dnssecQueryResult = dnssecClient.queryDnssec(question);
+            dnsQueryResult = dnssecQueryResult.dnsQueryResult;
+        } else {
+            dnsQueryResult = dnsClient.query(question);
+        }
+
+        return dnsQueryResult.response;
+    }
+
+}

smack-resolver-minidns-dox/src/main/java/org/jivesoftware/smackx/dox/resolver/minidns/package-info.java

@@ -0,0 +1,21 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * XEP-0418: DNS Queries over XMPP (Dox) using MiniDNS.
+ */
+package org.jivesoftware.smackx.dox.resolver.minidns;

smack-resolver-minidns-dox/src/test/java/org/jivesoftware/smackx/dox/resolver/minidns/DnsOverXmppMiniDnsResolverTest.java

@@ -0,0 +1,167 @@
+/**
+ *
+ * Copyright 2019 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.dox.resolver.minidns;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.junit.Test;
+import org.minidns.DnsCache;
+import org.minidns.DnsClient;
+import org.minidns.MiniDnsFuture;
+import org.minidns.dnsmessage.DnsMessage;
+import org.minidns.dnsmessage.DnsMessage.RESPONSE_CODE;
+import org.minidns.dnsmessage.Question;
+import org.minidns.dnsname.DnsName;
+import org.minidns.dnsqueryresult.CachedDnsQueryResult;
+import org.minidns.dnsqueryresult.DnsQueryResult;
+import org.minidns.dnssec.DnssecClient;
+import org.minidns.dnssec.DnssecValidationFailedException;
+import org.minidns.record.Record.TYPE;
+import org.minidns.source.DnsDataSource;
+
+public final class DnsOverXmppMiniDnsResolverTest {
+
+    @Test
+    public void dnsOverXmppMiniDnsResolverTest() throws IOException {
+        TestDnsDataSource dnsSource = new TestDnsDataSource();
+        TestDnsDataSource dnssecSource = new TestDnsDataSource();
+
+        DnsClient dnsClient = new DnsClient(NoopDnsCache.INSTANCE);
+        dnsClient.setDataSource(dnsSource);
+
+        DnssecClient dnssecClient = new DnssecClient(NoopDnsCache.INSTANCE);
+        dnssecClient.setDataSource(dnssecSource);
+
+        DnsOverXmppMiniDnsResolver doxResolver = new DnsOverXmppMiniDnsResolver(dnsClient, dnssecClient);
+
+        Question question = new Question("example.org", TYPE.A);
+
+        {
+            DnsMessage nondnssecQuery = question.asQueryMessage();
+
+            doxResolver.resolve(nondnssecQuery);
+
+            assertTrue(dnsSource.getAndResetWasQueried());
+            assertFalse(dnssecSource.getAndResetWasQueried());
+        }
+
+        {
+            DnsMessage.Builder dnssecQueryBuilder = question.asMessageBuilder();
+            dnssecQueryBuilder.getEdnsBuilder().setDnssecOk();
+            DnsMessage dnssecQuery = dnssecQueryBuilder.build();
+
+            DnssecValidationFailedException dnssecValidationFailedException = null;
+            try {
+                doxResolver.resolve(dnssecQuery);
+            } catch (DnssecValidationFailedException e) {
+                dnssecValidationFailedException = e;
+            }
+            // This exception is expected since we don't have a realy DNS source.
+            assertNotNull(dnssecValidationFailedException);
+
+            assertFalse(dnsSource.getAndResetWasQueried());
+            assertTrue(dnssecSource.getAndResetWasQueried());
+        }
+    }
+
+    public static class TestDnsDataSource implements DnsDataSource {
+
+        private final AtomicBoolean wasQueried = new AtomicBoolean();
+
+        public boolean getAndResetWasQueried() {
+            return wasQueried.getAndSet(false);
+        }
+
+        private void setWasQueried() {
+            wasQueried.set(true);
+        }
+
+        @Override
+        public DnsQueryResult query(DnsMessage query, InetAddress address, int port) throws IOException {
+            setWasQueried();
+            return new TestDnsQueryResult(query);
+        }
+
+        @Override
+        public MiniDnsFuture<DnsQueryResult, IOException> queryAsync(DnsMessage query, InetAddress address, int port,
+                OnResponseCallback onResponseCallback) {
+            setWasQueried();
+            DnsQueryResult result = new TestDnsQueryResult(query);
+            return MiniDnsFuture.from(result);
+        }
+
+        @Override
+        public int getUdpPayloadSize() {
+            return 0;
+        }
+
+        @Override
+        public int getTimeout() {
+            return 0;
+        }
+
+        @Override
+        public void setTimeout(int timeout) {
+        }
+
+        private static class TestDnsQueryResult extends DnsQueryResult {
+
+            protected TestDnsQueryResult(DnsMessage query) {
+                super(QueryMethod.testWorld, query, createNxDomainAnswerFor(query));
+            }
+
+            private static DnsMessage createNxDomainAnswerFor(DnsMessage query) {
+                Question question = query.getQuestion();
+
+                DnsMessage response = DnsMessage.builder()
+                    .setQuestion(question)
+                    .setRecursionAvailable(true)
+                    .setResponseCode(RESPONSE_CODE.NX_DOMAIN)
+                    .build();
+
+                return response;
+            }
+        }
+    }
+
+    // TODO: Workaround for NPE-if-no-cache-set bug in MiniDNS. Remove we use a MiniDNS version where this is fixed,
+    // i.e. one that has 864fbb5 ("Fix NPE in AbstractDnsClient if cache is 'null'")
+    private static class NoopDnsCache extends DnsCache {
+
+        private static final NoopDnsCache INSTANCE = new NoopDnsCache();
+
+        @Override
+        protected void putNormalized(DnsMessage normalizedQuery, DnsQueryResult result) {
+        }
+
+        @Override
+        public void offer(DnsMessage query, DnsQueryResult result, DnsName authoritativeZone) {
+        }
+
+        @Override
+        protected CachedDnsQueryResult getNormalized(DnsMessage normalizedQuery) {
+            return null;
+        }
+
+    }
+}

smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XMPPTCPConnection.java

@@ -121,7 +121,6 @@ import org.jivesoftware.smack.util.dns.HostAddress;
 import org.jxmpp.jid.impl.JidCreate;
 import org.jxmpp.jid.parts.Resourcepart;
 import org.jxmpp.stringprep.XmppStringprepException;
-import org.jxmpp.util.XmppStringUtils;
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
 
@@ -319,7 +318,7 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
      * @throws XmppStringprepException
      */
     public XMPPTCPConnection(CharSequence jid, String password) throws XmppStringprepException {
-        this(XmppStringUtils.parseLocalpart(jid.toString()), password, XmppStringUtils.parseDomain(jid.toString()));
+        this(XMPPTCPConnectionConfiguration.builder().setXmppAddressAndPassword(jid, password).build());
     }
 
     /**
@@ -482,10 +481,6 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
     }
 
     private void shutdown(boolean instant) {
-        if (disconnectedButResumeable) {
-            return;
-        }
-
         // First shutdown the writer, this will result in a closing stream element getting send to
         // the server
         LOGGER.finer("PacketWriter shutdown()");
@@ -503,6 +498,15 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
         CloseableUtil.maybeClose(socket, LOGGER);
 
         setWasAuthenticated();
+
+        // Wait for reader and writer threads to be terminated.
+        readerWriterSemaphore.acquireUninterruptibly(2);
+        readerWriterSemaphore.release(2);
+
+        if (disconnectedButResumeable) {
+            return;
+        }
+
         // If we are able to resume the stream, then don't set
         // connected/authenticated/usingTLS to false since we like behave like we are still
         // connected (e.g. sendStanza should not throw a NotConnectedException).
@@ -523,10 +527,6 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
         writer = null;
 
         initState();
-
-        // Wait for reader and writer threads to be terminated.
-        readerWriterSemaphore.acquireUninterruptibly(2);
-        readerWriterSemaphore.release(2);
     }
 
     @Override
@@ -860,6 +860,8 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
 
     protected class PacketReader {
 
+        private final String threadName = "Smack Reader (" + getConnectionCounter() + ')';
+
         XmlPullParser parser;
 
         private volatile boolean done;
@@ -874,13 +876,15 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
             Async.go(new Runnable() {
                 @Override
                 public void run() {
+                    LOGGER.finer(threadName + " start");
                     try {
                         parsePackets();
                     } finally {
+                        LOGGER.finer(threadName + " exit");
                         XMPPTCPConnection.this.readerWriterSemaphore.release();
                     }
                 }
-            }, "Smack Reader (" + getConnectionCounter() + ")");
+            }, threadName);
          }
 
         /**
@@ -1128,6 +1132,8 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
     protected class PacketWriter {
         public static final int QUEUE_SIZE = XMPPTCPConnection.QUEUE_SIZE;
 
+        private final String threadName = "Smack Writer (" + getConnectionCounter() + ')';
+
         private final ArrayBlockingQueueWithShutdown<Element> queue = new ArrayBlockingQueueWithShutdown<>(
                         QUEUE_SIZE, true);
 
@@ -1173,13 +1179,15 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
             Async.go(new Runnable() {
                 @Override
                 public void run() {
+                    LOGGER.finer(threadName + " start");
                     try {
                         writePackets();
                     } finally {
+                        LOGGER.finer(threadName + " exit");
                         XMPPTCPConnection.this.readerWriterSemaphore.release();
                     }
                 }
-            }, "Smack Writer (" + getConnectionCounter() + ")");
+            }, threadName);
         }
 
         private boolean done() {

version.gradle

@@ -10,6 +10,7 @@ allprojects {
 		// - https://issues.igniterealtime.org/browse/SMACK-858
 		jxmppVersion = '0.7.0-alpha5'
 		miniDnsVersion = '0.4.0-alpha3'
+		bouncyCastleVersion = '1.61'
 		smackMinAndroidSdk = 19
 	}
 }