Merge branch '4.4'

Add XmppElementUtil.castOrThrow()

build.gradle

@@ -122,8 +122,8 @@ allprojects {
 		// See also:
 		// - https://issues.apache.org/jira/browse/MNG-6232
 		// - https://issues.igniterealtime.org/browse/SMACK-858
-		jxmppVersion = '1.0.0'
-		miniDnsVersion = '1.0.0'
+		jxmppVersion = '[1.0.0, 1.0.999]'
+		miniDnsVersion = '[1.0.0, 1.0.999]'
 		smackMinAndroidSdk = 19
 		junitVersion = '5.6.2'
 		commonsIoVersion = '2.6'
@@ -288,6 +288,9 @@ tasks.withType(Javadoc) {
 		// fixtures, and we want to have mockito also available in
 		// test, so we use API here.
 		testFixturesApi "org.mockito:mockito-core:3.3.3"
+		
+		// To mock final classes
+		testImplementation 'org.mockito:mockito-inline:3.3.3'
 		testImplementation 'com.jamesmurty.utils:java-xmlbuilder:1.2'
 
 		errorprone 'com.google.errorprone:error_prone_core:2.3.4'
@@ -305,6 +308,13 @@ configure (junit4Projects) {
 	}
 }
 
+// We need to evaluate the child projects first because
+// - javadocAll needs the smack-core child to have already resolved
+//   the jXMPP/MiniDNS dependencies, so that we can the resovled
+//   version to link to those project's javadoc.
+// - We use the child's project description as description for the
+//   Maven POM.
+evaluationDependsOnChildren()
 task javadocAll(type: Javadoc) {
 	source javadocAllProjects.collect {project ->
 		project.sourceSets.main.allJava.findAll {
@@ -319,13 +329,15 @@ task javadocAll(type: Javadoc) {
 	classpath = files(subprojects.collect {project ->
 		project.sourceSets.main.compileClasspath})
 	classpath += files(androidBootClasspath)
+	def staticJxmppVersion = getResolvedVersion('org.jxmpp:jxmpp-core')
+	def staticMiniDnsVersion = getResolvedVersion('org.minidns:minidns-core')
 	options {
 		linkSource = true
 		use = true
 		links = [
 		"https://docs.oracle.com/javase/${javaMajor}/docs/api/",
-		"https://jxmpp.org/releases/$jxmppVersion/javadoc/",
-		"https://minidns.org/releases/$miniDnsVersion/javadoc/",
+		"https://jxmpp.org/releases/${staticJxmppVersion}/javadoc/",
+		"https://minidns.org/releases/${staticMiniDnsVersion}/javadoc/",
 		] as String[]
 		overview = "$projectDir/resources/javadoc-overview.html"
 	}
@@ -408,7 +420,6 @@ description = """\
 Smack ${version}
 ${oneLineDesc}."""
 
-evaluationDependsOnChildren()
 subprojects {
 	apply plugin: 'maven-publish'
 	apply plugin: 'signing'
@@ -678,19 +689,19 @@ task sinttestAll {
 }
 
 def getGitCommit() {
-	def dotGit = new File("$projectDir/.git")
+	def projectDirFile = new File("$projectDir")
+	def dotGit = new File(projectDirFile, ".git")
 	if (!dotGit.isDirectory()) return 'non-git build'
 
-	def projectDir = dotGit.getParentFile()
 	def cmd = 'git describe --always --tags --dirty=+'
-	def proc = cmd.execute(null, projectDir)
+	def proc = cmd.execute(null, projectDirFile)
 	proc.waitForOrKill(10 * 1000)
 
 	def gitCommit = proc.text.trim()
 	assert !gitCommit.isEmpty()
 
     def srCmd = 'git symbolic-ref --short HEAD'
-    def srProc = srCmd.execute(null, projectDir)
+    def srProc = srCmd.execute(null, projectDirFile)
     srProc.waitForOrKill(10 * 1000)
     if (srProc.exitValue() == 0) {
         // Only add the information if the git command was
@@ -740,3 +751,24 @@ def readVersionFile() {
 	}
 	versionFile.text.trim()
 }
+
+def getResolvedVersion(queriedProject = 'smack-core', component) {
+	def configuration = project(queriedProject)
+		.configurations
+		.compileClasspath
+
+	def artifact = configuration
+		.resolvedConfiguration
+		.resolvedArtifacts
+		.findAll {
+			// 'it' is of type ResolvedArtifact, 'id' of
+			// Component*Artifcat*Identifier, and we check the
+			// ComponentIdentifier.
+			it.id.getComponentIdentifier() instanceof org.gradle.api.artifacts.component.ModuleComponentIdentifier
+		}
+	    .find {
+			it.id.getComponentIdentifier().toString().startsWith(component + ':')
+		}
+
+	artifact.getModuleVersion().getId().getVersion()
+}

settings.gradle

@@ -16,6 +16,7 @@ include 'smack-core',
 		'smack-resolver-javax',
 		'smack-sasl-javax',
 		'smack-sasl-provided',
+		'smack-streammanagement',
 		'smack-legacy',
 		'smack-jingle-old',
 		'smack-bosh',
@@ -29,6 +30,7 @@ include 'smack-core',
 		'smack-omemo-signal-integration-test',
 		'smack-repl',
 		'smack-openpgp',
+		'smack-websocket',
 		'smack-xmlparser',
 		'smack-xmlparser-stax',
 		'smack-xmlparser-xpp3'

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

@@ -70,6 +70,7 @@ import org.jivesoftware.smack.filter.StanzaFilter;
 import org.jivesoftware.smack.filter.StanzaIdFilter;
 import org.jivesoftware.smack.internal.SmackTlsContext;
 import org.jivesoftware.smack.iqrequest.IQRequestHandler;
+import org.jivesoftware.smack.packet.AbstractStreamOpen;
 import org.jivesoftware.smack.packet.Bind;
 import org.jivesoftware.smack.packet.ErrorIQ;
 import org.jivesoftware.smack.packet.ExtensionElement;
@@ -522,6 +523,9 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         closingStreamReceived = false;
         streamId = null;
 
+        // The connection should not be connected nor marked as such prior calling connectInternal().
+        assert !connected;
+
         try {
             // Perform the actual connection to the XMPP service
             connectInternal();
@@ -537,8 +541,9 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
             throw e;
         }
 
-        // Make note of the fact that we're now connected.
-        connected = true;
+        // If connectInternal() did not throw, then this connection must now be marked as connected.
+        assert connected;
+
         callConnectionConnectedListener();
 
         return this;
@@ -2224,7 +2229,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
         }
     }
 
-    protected void sendStreamOpen() throws NotConnectedException, InterruptedException {
+    protected final void sendStreamOpen() throws NotConnectedException, InterruptedException {
         // If possible, provide the receiving entity of the stream open tag, i.e. the server, as much information as
         // possible. The 'to' attribute is *always* available. The 'from' attribute if set by the user and no external
         // mechanism is used to determine the local entity (user). And the 'id' attribute is available after the first
@@ -2236,10 +2241,18 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
             from = XmppStringUtils.completeJidFrom(localpart, to);
         }
         String id = getStreamId();
+        String lang = config.getXmlLang();
 
-        StreamOpen streamOpen = new StreamOpen(to, from, id, config.getXmlLang(), StreamOpen.StreamContentNamespace.client);
+        AbstractStreamOpen streamOpen = getStreamOpen(to, from, id, lang);
         sendNonza(streamOpen);
+        updateOutgoingStreamXmlEnvironmentOnStreamOpen(streamOpen);
+    }
 
+    protected AbstractStreamOpen getStreamOpen(CharSequence to, CharSequence from, String id, String lang) {
+        return new StreamOpen(to, from, id, lang);
+    }
+
+    protected void updateOutgoingStreamXmlEnvironmentOnStreamOpen(AbstractStreamOpen streamOpen) {
         XmlEnvironment.Builder xmlEnvironmentBuilder = XmlEnvironment.builder();
         xmlEnvironmentBuilder.with(streamOpen);
         outgoingStreamXmlEnvironment = xmlEnvironmentBuilder.build();

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

@@ -364,7 +364,7 @@ public abstract class SmackException extends Exception {
             if (lookupFailures.isEmpty()) {
                 sb.append("No endpoint lookup finished within the timeout");
             } else {
-                sb.append("Not endpoints could be discovered due the following lookup failures: ");
+                sb.append("No endpoints could be discovered due the following lookup failures: ");
                 StringUtils.appendTo(lookupFailures, sb);
             }
 

smack-core/src/main/java/org/jivesoftware/smack/altconnections/HttpLookupMethod.java

@@ -27,6 +27,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.util.ParserUtils;
 import org.jivesoftware.smack.xml.XmlPullParser;
 import org.jivesoftware.smack.xml.XmlPullParserException;
 
@@ -132,6 +133,7 @@ public final class HttpLookupMethod {
      * @throws URISyntaxException exception to indicate that a string could not be parsed as a URI reference
      */
     public static List<URI> parseXrdLinkReferencesFor(XmlPullParser parser, String relation) throws IOException, XmlPullParserException, URISyntaxException {
+        ParserUtils.forwardToStartElement(parser);
         List<URI> uriList = new ArrayList<>();
         int initialDepth = parser.getDepth();
 

smack-core/src/main/java/org/jivesoftware/smack/c2s/ModularXmppClientToServerConnection.java

@@ -61,12 +61,13 @@ import org.jivesoftware.smack.fsm.StateTransitionResult;
 import org.jivesoftware.smack.fsm.StateTransitionResult.AttemptResult;
 import org.jivesoftware.smack.internal.AbstractStats;
 import org.jivesoftware.smack.internal.SmackTlsContext;
+import org.jivesoftware.smack.packet.AbstractStreamClose;
+import org.jivesoftware.smack.packet.AbstractStreamOpen;
 import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.packet.Nonza;
 import org.jivesoftware.smack.packet.Presence;
 import org.jivesoftware.smack.packet.Stanza;
-import org.jivesoftware.smack.packet.StreamClose;
 import org.jivesoftware.smack.packet.StreamError;
 import org.jivesoftware.smack.packet.TopLevelStreamElement;
 import org.jivesoftware.smack.packet.XmlEnvironment;
@@ -81,7 +82,9 @@ import org.jivesoftware.smack.util.Supplier;
 import org.jivesoftware.smack.xml.XmlPullParser;
 import org.jivesoftware.smack.xml.XmlPullParserException;
 
+import org.jxmpp.jid.DomainBareJid;
 import org.jxmpp.jid.parts.Resourcepart;
+import org.jxmpp.util.XmppStringUtils;
 
 public final class ModularXmppClientToServerConnection extends AbstractXMPPConnection {
 
@@ -135,6 +138,11 @@ public final class ModularXmppClientToServerConnection extends AbstractXMPPConne
                 ModularXmppClientToServerConnection.this.notifyConnectionError(e);
             }
 
+            @Override
+            public void setCurrentConnectionExceptionAndNotify(Exception exception) {
+                ModularXmppClientToServerConnection.this.setCurrentConnectionExceptionAndNotify(exception);
+            }
+
             @Override
             public void onStreamOpen(XmlPullParser parser) {
                 ModularXmppClientToServerConnection.this.onStreamOpen(parser);
@@ -176,6 +184,11 @@ public final class ModularXmppClientToServerConnection extends AbstractXMPPConne
                 return inputOutputFilters.listIterator(inputOutputFilters.size());
             }
 
+            @Override
+            public void waitForFeaturesReceived(String waitFor) throws InterruptedException, SmackException, XMPPException {
+                ModularXmppClientToServerConnection.this.waitForFeaturesReceived(waitFor);
+            }
+
             @Override
             public void newStreamOpenWaitForFeaturesSequence(String waitFor) throws InterruptedException,
                             SmackException, XMPPException {
@@ -199,7 +212,7 @@ public final class ModularXmppClientToServerConnection extends AbstractXMPPConne
             }
 
             @Override
-            public void waitForCondition(Supplier<Boolean> condition, String waitFor)
+            public void waitForConditionOrThrowConnectionException(Supplier<Boolean> condition, String waitFor)
                             throws InterruptedException, SmackException, XMPPException {
                 ModularXmppClientToServerConnection.this.waitForConditionOrThrowConnectionException(condition, waitFor);
             }
@@ -217,6 +230,7 @@ public final class ModularXmppClientToServerConnection extends AbstractXMPPConne
             @Override
             public void setTransport(XmppClientToServerTransport xmppTransport) {
                 ModularXmppClientToServerConnection.this.activeTransport = xmppTransport;
+                ModularXmppClientToServerConnection.this.connected = true;
             }
 
         };
@@ -556,13 +570,35 @@ public final class ModularXmppClientToServerConnection extends AbstractXMPPConne
         waitForConditionOrThrowConnectionException(() -> featuresReceived, waitFor);
     }
 
+    @Override
+    protected AbstractStreamOpen getStreamOpen(CharSequence to, CharSequence from, String id, String lang) {
+        StreamOpenAndCloseFactory streamOpenAndCloseFactory = activeTransport.getStreamOpenAndCloseFactory();
+        return streamOpenAndCloseFactory.createStreamOpen(to, from, id, lang);
+    }
+
     protected void newStreamOpenWaitForFeaturesSequence(String waitFor) throws InterruptedException,
                     SmackException, XMPPException {
         prepareToWaitForFeaturesReceived();
-        sendStreamOpen();
+
+        // Create StreamOpen from StreamOpenAndCloseFactory via underlying transport.
+        StreamOpenAndCloseFactory streamOpenAndCloseFactory = activeTransport.getStreamOpenAndCloseFactory();
+        CharSequence from = null;
+        CharSequence localpart = connectionInternal.connection.getConfiguration().getUsername();
+        DomainBareJid xmppServiceDomain = getXMPPServiceDomain();
+        if (localpart != null) {
+            from = XmppStringUtils.completeJidFrom(localpart, xmppServiceDomain);
+        }
+        AbstractStreamOpen streamOpen = streamOpenAndCloseFactory.createStreamOpen(xmppServiceDomain, from, getStreamId(), getConfiguration().getXmlLang());
+        sendStreamOpen(streamOpen);
+
         waitForFeaturesReceived(waitFor);
     }
 
+    private void sendStreamOpen(AbstractStreamOpen streamOpen) throws NotConnectedException, InterruptedException {
+        sendNonza(streamOpen);
+        updateOutgoingStreamXmlEnvironmentOnStreamOpen(streamOpen);
+    }
+
     public static class DisconnectedStateDescriptor extends StateDescriptor {
         protected DisconnectedStateDescriptor() {
             super(DisconnectedState.class, StateDescriptor.Property.finalState);
@@ -904,7 +940,9 @@ public final class ModularXmppClientToServerConnection extends AbstractXMPPConne
         public StateTransitionResult.AttemptResult transitionInto(WalkStateGraphContext walkStateGraphContext) {
             closingStreamReceived = false;
 
-            boolean streamCloseIssued = outgoingElementsQueue.offerAndShutdown(StreamClose.INSTANCE);
+            StreamOpenAndCloseFactory openAndCloseFactory = activeTransport.getStreamOpenAndCloseFactory();
+            AbstractStreamClose closeStreamElement = openAndCloseFactory.createStreamClose();
+            boolean streamCloseIssued = outgoingElementsQueue.offerAndShutdown(closeStreamElement);
 
             if (streamCloseIssued) {
                 activeTransport.notifyAboutNewOutgoingElements();

smack-core/src/main/java/org/jivesoftware/smack/c2s/ModularXmppClientToServerConnectionConfiguration.java

@@ -96,7 +96,7 @@ public final class ModularXmppClientToServerConnectionConfiguration extends Conn
             return new ModularXmppClientToServerConnectionConfiguration(this);
         }
 
-        void addModule(ModularXmppClientToServerConnectionModuleDescriptor connectionModule) {
+        public void addModule(ModularXmppClientToServerConnectionModuleDescriptor connectionModule) {
             Class<? extends ModularXmppClientToServerConnectionModuleDescriptor> moduleDescriptorClass = connectionModule.getClass();
             if (modulesDescriptors.containsKey(moduleDescriptorClass)) {
                 throw new IllegalArgumentException("A connection module for " + moduleDescriptorClass + " is already configured");

smack-core/src/main/java/org/jivesoftware/smack/c2s/StreamOpenAndCloseFactory.java

@@ -0,0 +1,26 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar.
+ *
+ * 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.c2s;
+
+import org.jivesoftware.smack.packet.AbstractStreamClose;
+import org.jivesoftware.smack.packet.AbstractStreamOpen;
+
+public interface StreamOpenAndCloseFactory {
+    AbstractStreamOpen createStreamOpen(CharSequence to, CharSequence from, String id, String lang);
+
+    AbstractStreamClose createStreamClose();
+}

smack-core/src/main/java/org/jivesoftware/smack/c2s/XmppClientToServerTransport.java

@@ -58,6 +58,8 @@ public abstract class XmppClientToServerTransport {
         return getSslSession() != null;
     }
 
+    public abstract StreamOpenAndCloseFactory getStreamOpenAndCloseFactory();
+
     public abstract Stats getStats();
 
     public abstract static class Stats {

smack-core/src/main/java/org/jivesoftware/smack/c2s/internal/ModularXmppClientToServerConnectionInternal.java

@@ -85,6 +85,8 @@ public abstract class ModularXmppClientToServerConnectionInternal {
 
     public abstract void notifyConnectionError(Exception e);
 
+    public abstract void setCurrentConnectionExceptionAndNotify(Exception exception);
+
     public abstract void onStreamOpen(XmlPullParser parser);
 
     public abstract void onStreamClosed();
@@ -99,6 +101,8 @@ public abstract class ModularXmppClientToServerConnectionInternal {
 
     public abstract ListIterator<XmppInputOutputFilter> getXmppInputOutputFilterEndIterator();
 
+    public abstract void waitForFeaturesReceived(String waitFor) throws InterruptedException, SmackException, XMPPException;
+
     public abstract void newStreamOpenWaitForFeaturesSequence(String waitFor) throws InterruptedException,
                     NoResponseException, NotConnectedException, SmackException, XMPPException;
 
@@ -110,11 +114,17 @@ public abstract class ModularXmppClientToServerConnectionInternal {
 
     public abstract void asyncGo(Runnable runnable);
 
-    public abstract void waitForCondition(Supplier<Boolean> condition, String waitFor) throws InterruptedException, SmackException, XMPPException;
+    public abstract void waitForConditionOrThrowConnectionException(Supplier<Boolean> condition, String waitFor) throws InterruptedException, SmackException, XMPPException;
 
     public abstract void notifyWaitingThreads();
 
     public abstract void setCompressionEnabled(boolean compressionEnabled);
 
+    /**
+     * Set the active transport (TCP, BOSH, WebSocket, …) to be used for the XMPP connection. Also marks the connection
+     * as connected.
+     *
+     * @param xmppTransport the active transport.
+     */
     public abstract void setTransport(XmppClientToServerTransport xmppTransport);
 }

smack-core/src/main/java/org/jivesoftware/smack/fsm/StateDescriptor.java

@@ -22,12 +22,16 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection;
 import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
 
 public abstract class StateDescriptor {
 
+    private static final Logger LOGGER = Logger.getLogger(StateDescriptor.class.getName());
+
     public enum Property {
         multiVisitState,
         finalState,
@@ -133,10 +137,35 @@ public abstract class StateDescriptor {
         addAndCheckNonExistent(precedenceOver, subordinate);
     }
 
-    protected void declareInferiortyTo(Class<? extends StateDescriptor> superior) {
+    protected void declarePrecedenceOver(String subordinate) {
+        addAndCheckNonExistent(precedenceOver, subordinate);
+    }
+
+    protected void declareInferiorityTo(Class<? extends StateDescriptor> superior) {
         addAndCheckNonExistent(inferiorTo, superior);
     }
 
+    protected void declareInferiorityTo(String superior) {
+        addAndCheckNonExistent(inferiorTo, superior);
+    }
+
+    private static void addAndCheckNonExistent(Set<Class<? extends StateDescriptor>> set, String clazzName) {
+        Class<?> clazz;
+        try {
+            clazz = Class.forName(clazzName);
+        } catch (ClassNotFoundException e) {
+            // The state descriptor class is not in classpath, which probably means that the smack module is not loaded
+            // into the classpath. Hence we can silently ignore that.
+            LOGGER.log(Level.FINEST, "Ignoring unknown state descriptor '" + clazzName + "'", e);
+            return;
+        }
+        if (!StateDescriptor.class.isAssignableFrom(clazz)) {
+            throw new IllegalArgumentException(clazz + " is no state descriptor class");
+        }
+        Class<? extends StateDescriptor> stateDescriptorClass = clazz.asSubclass(StateDescriptor.class);
+        addAndCheckNonExistent(set, stateDescriptorClass);
+    }
+
     private static <E> void addAndCheckNonExistent(Set<E> set, E e) {
         boolean newElement = set.add(e);
         if (!newElement) {

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

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.packet;
+
+public abstract class AbstractStreamClose implements Nonza {
+}

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

@@ -0,0 +1,89 @@
+/**
+ *
+ * Copyright 2020 Florian Schmaus, Aditya Borikar
+ *
+ * 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.packet;
+
+import org.jivesoftware.smack.XMPPConnection;
+import org.jivesoftware.smack.packet.StreamOpen.StreamContentNamespace;
+import org.jivesoftware.smack.util.StringUtils;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+
+/**
+ * AbstractStreamOpen is actually a {@link TopLevelStreamElement}, however we
+ * implement {@link Nonza} here. This is because, {@link XMPPConnection} doesn't
+ * yet support sending {@link TopLevelStreamElement} directly and the same can only
+ * be achieved through {@link XMPPConnection#sendNonza(Nonza)}.
+ */
+public abstract class AbstractStreamOpen implements Nonza {
+    public static final String CLIENT_NAMESPACE = "jabber:client";
+    public static final String SERVER_NAMESPACE = "jabber:server";
+
+    /**
+     * RFC 6120 § 4.7.5.
+     */
+    public static final String VERSION = "1.0";
+
+    /**
+     * RFC 6120 § 4.7.1.
+     */
+    protected final String from;
+
+    /**
+     * RFC 6120 § 4.7.2.
+     */
+    protected final String to;
+
+    /**
+     * RFC 6120 § 4.7.3.
+     */
+    protected final String id;
+
+    /**
+     * RFC 6120 § 4.7.4.
+     */
+    protected final String lang;
+
+    /**
+     * RFC 6120 § 4.8.2.
+     */
+    protected final String contentNamespace;
+
+    public AbstractStreamOpen(CharSequence to, CharSequence from, String id, String lang) {
+        this(to, from, id, lang, StreamContentNamespace.client);
+    }
+
+    public AbstractStreamOpen(CharSequence to, CharSequence from, String id, String lang, StreamContentNamespace ns) {
+        this.to = StringUtils.maybeToString(to);
+        this.from = StringUtils.maybeToString(from);
+        this.id = id;
+        this.lang = lang;
+        switch (ns) {
+        case client:
+            this.contentNamespace = CLIENT_NAMESPACE;
+            break;
+        case server:
+            this.contentNamespace = SERVER_NAMESPACE;
+            break;
+        default:
+            throw new IllegalStateException();
+        }
+    }
+
+    protected final void addCommonAttributes(XmlStringBuilder xml) {
+        xml.optAttribute("to", to);
+        xml.optAttribute("version", VERSION);
+    }
+}

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

@@ -90,11 +90,12 @@ public interface StanzaView extends XmlLangElement {
     default <E extends ExtensionElement> E getExtension(Class<E> extensionElementClass) {
         QName qname = XmppElementUtil.getQNameFor(extensionElementClass);
         ExtensionElement extensionElement = getExtension(qname);
-        if (!extensionElementClass.isInstance(extensionElement)) {
+
+        if (extensionElement == null) {
             return null;
         }
 
-        return extensionElementClass.cast(extensionElement);
+        return XmppElementUtil.castOrThrow(extensionElement, extensionElementClass);
     }
 
     /**

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

@@ -16,7 +16,7 @@
  */
 package org.jivesoftware.smack.packet;
 
-public final class StreamClose implements Nonza {
+public final class StreamClose extends AbstractStreamClose {
 
     public static final StreamClose INSTANCE = new StreamClose();
 

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

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014-2019 Florian Schmaus
+ * Copyright © 2014-2020 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,49 +17,14 @@
 
 package org.jivesoftware.smack.packet;
 
-import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
 /**
  * The stream open <b>tag</b>.
  */
-public class StreamOpen implements Nonza {
-
+public final class StreamOpen extends AbstractStreamOpen {
     public static final String ELEMENT = "stream:stream";
 
-    public static final String CLIENT_NAMESPACE = "jabber:client";
-    public static final String SERVER_NAMESPACE = "jabber:server";
-
-    /**
-     * RFC 6120 § 4.7.5.
-     */
-    public static final String VERSION = "1.0";
-
-    /**
-     * RFC 6120 § 4.7.1.
-     */
-    private final String from;
-
-    /**
-     * RFC 6120 § 4.7.2.
-     */
-    private final String to;
-
-    /**
-     * RFC 6120 § 4.7.3.
-     */
-    private final String id;
-
-    /**
-     * RFC 6120 § 4.7.4.
-     */
-    private final String lang;
-
-    /**
-     * RFC 6120 § 4.8.2.
-     */
-    private final String contentNamespace;
-
     public StreamOpen(CharSequence to) {
        this(to, null, null, null, StreamContentNamespace.client);
     }
@@ -68,21 +33,12 @@ public class StreamOpen implements Nonza {
         this(to, from, id, "en", StreamContentNamespace.client);
     }
 
+    public StreamOpen(CharSequence to, CharSequence from, String id, String lang) {
+        super(to, from, id, lang);
+    }
+
     public StreamOpen(CharSequence to, CharSequence from, String id, String lang, StreamContentNamespace ns) {
-        this.to = StringUtils.maybeToString(to);
-        this.from = StringUtils.maybeToString(from);
-        this.id = id;
-        this.lang = lang;
-        switch (ns) {
-        case client:
-            this.contentNamespace = CLIENT_NAMESPACE;
-            break;
-        case server:
-            this.contentNamespace = SERVER_NAMESPACE;
-            break;
-        default:
-            throw new IllegalStateException();
-        }
+        super(to, from, id, lang, ns);
     }
 
     @Override

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

@@ -71,7 +71,7 @@ public class XmlEnvironment {
     }
 
     public String getEffectiveNamespaceOrUse(String namespace) {
-        String effectiveNamespace = getEffectiveLanguage();
+        String effectiveNamespace = getEffectiveNamespace();
         if (StringUtils.isNullOrEmpty(effectiveNamespace)) {
             return namespace;
         }
@@ -162,7 +162,7 @@ public class XmlEnvironment {
             return this;
         }
 
-        public Builder with(StreamOpen streamOpen) {
+        public Builder with(AbstractStreamOpen streamOpen) {
             withNamespace(streamOpen.getNamespace());
             withLanguage(streamOpen.getLanguage());
             return this;

smack-core/src/main/java/org/jivesoftware/smack/provider/ProviderManager.java

@@ -243,7 +243,11 @@ public final class ProviderManager {
      */
     public static ExtensionElementProvider<ExtensionElement> getExtensionProvider(String elementName, String namespace) {
         QName key = getQName(elementName, namespace);
-        return extensionProviders.get(key);
+        return getExtensionProvider(key);
+    }
+
+    public static ExtensionElementProvider<ExtensionElement> getExtensionProvider(QName qname) {
+        return extensionProviders.get(qname);
     }
 
     /**

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

@@ -82,14 +82,7 @@ public class PacketParserUtils {
 
     public static XmlPullParser getParserFor(Reader reader) throws XmlPullParserException, IOException {
         XmlPullParser parser = SmackXmlParser.newXmlParser(reader);
-        // Wind the parser forward to the first start tag
-        XmlPullParser.Event event = parser.getEventType();
-        while (event != XmlPullParser.Event.START_ELEMENT) {
-            if (event == XmlPullParser.Event.END_DOCUMENT) {
-                throw new IllegalArgumentException("Document contains no start tag");
-            }
-            event = parser.next();
-        }
+        ParserUtils.forwardToStartElement(parser);
         return parser;
     }
 

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

@@ -63,6 +63,17 @@ public class ParserUtils {
         assert parser.getEventType() == XmlPullParser.Event.END_ELEMENT;
     }
 
+    public static void forwardToStartElement(XmlPullParser parser) throws XmlPullParserException, IOException {
+         // Wind the parser forward to the first start tag
+        XmlPullParser.Event event = parser.getEventType();
+        while (event != XmlPullParser.Event.START_ELEMENT) {
+            if (event == XmlPullParser.Event.END_DOCUMENT) {
+                throw new IllegalArgumentException("Document contains no start tag");
+            }
+            event = parser.next();
+        }
+    }
+
     public static void forwardToEndTagOfDepth(XmlPullParser parser, int depth)
                     throws XmlPullParserException, IOException {
         XmlPullParser.Event event = parser.getEventType();

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

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2014-2019 Florian Schmaus
+ * Copyright 2014-2020 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,6 @@ import java.util.Date;
 import java.util.List;
 
 import org.jivesoftware.smack.packet.Element;
-import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.FullyQualifiedElement;
 import org.jivesoftware.smack.packet.NamedElement;
 import org.jivesoftware.smack.packet.XmlEnvironment;
@@ -43,7 +42,7 @@ public class XmlStringBuilder implements Appendable, CharSequence, Element {
         effectiveXmlEnvironment = null;
     }
 
-    public XmlStringBuilder(ExtensionElement pe) {
+    public XmlStringBuilder(FullyQualifiedElement pe) {
         this(pe, null);
     }
 

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

@@ -23,17 +23,31 @@ import java.util.logging.Logger;
 
 import javax.xml.namespace.QName;
 
+import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.FullyQualifiedElement;
+import org.jivesoftware.smack.packet.StandardExtensionElement;
+import org.jivesoftware.smack.provider.ProviderManager;
+
+import org.jxmpp.util.cache.LruCache;
 
 public class XmppElementUtil {
 
+    private static final LruCache<Class<? extends FullyQualifiedElement>, QName> CLASS_TO_QNAME_CACHE = new LruCache<>(512);
+
     public static final Logger LOGGER = Logger.getLogger(XmppElementUtil.class.getName());
 
     public static QName getQNameFor(Class<? extends FullyQualifiedElement> fullyQualifiedElement) {
+        QName qname = CLASS_TO_QNAME_CACHE.get(fullyQualifiedElement);
+        if (qname != null) {
+            return qname;
+        }
+
         try {
             Object qnameObject = fullyQualifiedElement.getField("QNAME").get(null);
             if (QName.class.isAssignableFrom(qnameObject.getClass())) {
-                return (QName) qnameObject;
+                qname = (QName) qnameObject;
+                CLASS_TO_QNAME_CACHE.put(fullyQualifiedElement, qname);
+                return qname;
             }
             LOGGER.warning("The QNAME field of " + fullyQualifiedElement + " is not of type QNAME.");
         } catch (NoSuchFieldException e) {
@@ -52,24 +66,52 @@ public class XmppElementUtil {
             throw new IllegalArgumentException("The " + fullyQualifiedElement + " has no ELEMENT, NAMESPACE or QNAME member. Consider adding QNAME", e);
         }
 
-        return new QName(namespace, element);
+        qname = new QName(namespace, element);
+        CLASS_TO_QNAME_CACHE.put(fullyQualifiedElement, qname);
+        return qname;
     }
 
-    public static <E extends FullyQualifiedElement, R extends FullyQualifiedElement> List<R> getElementsFrom(
-                    MultiMap<QName, E> elementMap, Class<R> extensionElementClass) {
+    public static <E extends ExtensionElement> List<E> getElementsFrom(
+                    MultiMap<QName, ExtensionElement> elementMap, Class<E> extensionElementClass) {
         QName qname = XmppElementUtil.getQNameFor(extensionElementClass);
 
-        List<E> extensionElements = elementMap.getAll(qname);
+        List<ExtensionElement> extensionElements = elementMap.getAll(qname);
 
         if (extensionElements.isEmpty()) {
             return Collections.emptyList();
         }
 
-        List<R> res = new ArrayList<>(extensionElements.size());
-        for (E extensionElement : extensionElements) {
-            R e = extensionElementClass.cast(extensionElement);
+        List<E> res = new ArrayList<>(extensionElements.size());
+        for (ExtensionElement extensionElement : extensionElements) {
+            E e = castOrThrow(extensionElement, extensionElementClass);
             res.add(e);
         }
         return res;
     }
+
+    public static <E extends ExtensionElement> E castOrThrow(ExtensionElement extensionElement, Class<E> extensionElementClass) {
+        if (!extensionElementClass.isInstance(extensionElement)) {
+            final QName qname = getQNameFor(extensionElementClass);
+
+            final String detailMessage;
+            if (extensionElement instanceof StandardExtensionElement) {
+                detailMessage = "because there is no according extension element provider registered with ProviderManager for "
+                                + qname
+                                + ". WARNING: This indicates a serious problem with your Smack setup, probably causing Smack not being able to properly initialize itself.";
+            } else {
+                Object provider = ProviderManager.getExtensionProvider(qname);
+                detailMessage = "because there is an inconsistency with the provider registered with ProviderManager: the active provider for "
+                                + qname + " '" + provider.getClass()
+                                + "' does not return instances of type " + extensionElementClass
+                                + ", but instead returns instances of type " + extensionElement.getClass() + ".";
+            }
+
+            String message = "Extension element is not of expected class '" + extensionElementClass.getName() + "', "
+                            + detailMessage;
+            throw new IllegalStateException(message);
+        }
+
+        return extensionElementClass.cast(extensionElement);
+    }
+
 }

smack-core/src/main/java/org/jivesoftware/smack/util/rce/RemoteConnectionEndpointLookupFailure.java

@@ -18,6 +18,7 @@ package org.jivesoftware.smack.util.rce;
 
 import org.jivesoftware.smack.util.ToStringUtil;
 
+import org.jxmpp.jid.DomainBareJid;
 import org.minidns.dnsname.DnsName;
 
 public abstract class RemoteConnectionEndpointLookupFailure {
@@ -67,4 +68,17 @@ public abstract class RemoteConnectionEndpointLookupFailure {
             return dnsName;
         }
     }
+
+    public static class HttpLookupFailure extends RemoteConnectionEndpointLookupFailure {
+        private final DomainBareJid host;
+
+        public HttpLookupFailure(DomainBareJid host, Exception exception) {
+            super("Http lookup exception for " + host, exception);
+            this.host = host;
+        }
+
+        public DomainBareJid getHost() {
+            return host;
+        }
+    }
 }

smack-core/src/main/resources/org.jivesoftware.smack/smack-config.xml

@@ -20,6 +20,7 @@
         <className>org.jivesoftware.smack.android.AndroidSmackInitializer</className>
         <className>org.jivesoftware.smack.java7.Java7SmackInitializer</className>
         <className>org.jivesoftware.smack.im.SmackImInitializer</className>
+        <className>org.jivesoftware.smack.websocket.WebsocketInitializer</className>
         <className>org.jivesoftware.smackx.omemo.OmemoInitializer</className>
         <className>org.jivesoftware.smackx.ox.util.OpenPgpInitializer</className>
     </optionalStartupClasses>

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

@@ -18,9 +18,11 @@ package org.jivesoftware.smackx.mam.element;
 
 import java.util.List;
 
+import javax.xml.namespace.QName;
+
 import org.jivesoftware.smack.packet.Element;
 import org.jivesoftware.smack.packet.ExtensionElement;
-import org.jivesoftware.smack.packet.Message;
+import org.jivesoftware.smack.packet.MessageView;
 import org.jivesoftware.smack.util.StringUtils;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 
@@ -54,6 +56,11 @@ public class MamElements {
          */
         public static final String ELEMENT = "result";
 
+        /**
+         * The qualified name of the MAM result extension element.
+         */
+        public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
         /**
          * id of the result.
          */
@@ -139,8 +146,8 @@ public class MamElements {
             return xml;
         }
 
-        public static MamResultExtension from(Message message) {
-            return (MamResultExtension) message.getExtensionElement(ELEMENT, NAMESPACE);
+        public static MamResultExtension from(MessageView message) {
+            return message.getExtension(MamResultExtension.class);
         }
 
     }

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

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017-2019 Florian Schmaus
+ * Copyright 2017-2020 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -151,7 +151,7 @@ public class JingleReason implements FullyQualifiedElement {
 
         @Override
         public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
-            XmlStringBuilder xml = new XmlStringBuilder(this);
+            XmlStringBuilder xml = new XmlStringBuilder(this, enclosingNamespace);
             xml.rightAngleBracket();
 
             xml.openElement(reason.asString);

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

@@ -44,6 +44,7 @@ import org.jivesoftware.smack.tcp.XMPPTCPConnection;
 import org.jivesoftware.smack.tcp.XMPPTCPConnectionConfiguration;
 import org.jivesoftware.smack.util.MultiMap;
 import org.jivesoftware.smack.util.StringUtils;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModuleDescriptor;
 
 import org.jivesoftware.smackx.admin.ServiceAdministrationManager;
 import org.jivesoftware.smackx.iqregister.AccountManager;
@@ -86,6 +87,15 @@ public class XmppConnectionManager {
                             .applyExtraConfguration(cb -> cb.removeModule(CompressionModuleDescriptor.class))
                             .build()
             );
+            addConnectionDescriptor(
+                    XmppConnectionDescriptor.buildWith(ModularXmppClientToServerConnection.class, ModularXmppClientToServerConnectionConfiguration.class, ModularXmppClientToServerConnectionConfiguration.Builder.class)
+                    .withNickname("modular-websocket")
+                    .applyExtraConfguration(cb -> {
+                        cb.removeAllModules();
+                        cb.addModule(XmppWebsocketTransportModuleDescriptor.class);
+                    })
+                    .build()
+            );
         } catch (NoSuchMethodException | SecurityException e) {
             throw new AssertionError(e);
         }

smack-java8-full/build.gradle

@@ -12,6 +12,7 @@ dependencies {
 	api project(':smack-openpgp')
 	api project(':smack-resolver-minidns')
 	api project(':smack-resolver-minidns-dox')
+	api project(':smack-websocket')
 	api project(':smack-tcp')
 
 	testImplementation 'com.google.guava:guava:28.2-jre'

smack-java8-full/src/test/resources/state-graph.dot

@@ -1,6 +1,6 @@
 digraph {
   "Disconnected" -> "LookupRemoteConnectionEndpoints";
-  "LookupRemoteConnectionEndpoints" -> "EstablishingTcpConnection";
+  "LookupRemoteConnectionEndpoints" -> "EstablishingTcpConnection" [xlabel="1"];
   "EstablishingTcpConnection" -> "EstablishTls (RFC 6120 § 5)" [xlabel="1"];
   "EstablishTls (RFC 6120 § 5)" -> "ConnectedButUnauthenticated";
   "ConnectedButUnauthenticated" -> "Bind2 (XEP-0386)" [xlabel="1"];
@@ -32,5 +32,7 @@ digraph {
   "ConnectedButUnauthenticated" -> "InstantShutdown" [xlabel="5"];
 "ConnectedButUnauthenticated" [ style=filled ]
   "EstablishingTcpConnection" -> "ConnectedButUnauthenticated" [xlabel="2"];
+  "LookupRemoteConnectionEndpoints" -> "EstablishingWebsocketConnection" [xlabel="2"];
+  "EstablishingWebsocketConnection" -> "ConnectedButUnauthenticated";
 "Disconnected" [ style=filled ]
 }

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

@@ -0,0 +1,53 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * This file is part of smack-repl.
+ *
+ * smack-repl is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
+ */
+package org.igniterealtime.smack.smackrepl;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+import org.jivesoftware.smack.SmackException;
+import org.jivesoftware.smack.XMPPException;
+
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionConfiguration;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModuleDescriptor;
+
+public class WebsocketConnection {
+
+    public static void main(String[] args) throws SmackException, IOException, XMPPException, InterruptedException, URISyntaxException {
+        ModularXmppClientToServerConnectionConfiguration.Builder builder = ModularXmppClientToServerConnectionConfiguration.builder();
+        builder.removeAllModules();
+        builder.setXmppAddressAndPassword(args[0], args[1]);
+
+        // Set a fallback uri into websocket transport descriptor and add this descriptor into connection builder.
+        XmppWebsocketTransportModuleDescriptor.Builder websocketBuilder = XmppWebsocketTransportModuleDescriptor.getBuilder(builder);
+        websocketBuilder.explicitlySetWebsocketEndpointAndDiscovery(new URI(args[2]), false);
+        builder.addModule(websocketBuilder.build());
+
+        ModularXmppClientToServerConnectionConfiguration config = builder.build();
+        ModularXmppClientToServerConnection connection = new ModularXmppClientToServerConnection(config);
+
+        connection.connect();
+        connection.login();
+        connection.disconnect();
+    }
+}

smack-streammanagement/build.gradle

@@ -0,0 +1,8 @@
+description = """\
+Smack support for XMPP Stream Management (XEP-0198)."""
+
+dependencies {
+	api project(':smack-core')
+
+	testFixturesApi(testFixtures(project(":smack-core")))
+}

smack-streammanagement/src/main/java/org/jivesoftware/smack/sm/StreamManagementModule.java

@@ -91,7 +91,7 @@ public class StreamManagementModule extends ModularXmppClientToServerConnectionM
             addPredeccessor(AuthenticatedButUnboundStateDescriptor.class);
             addSuccessor(AuthenticatedAndResourceBoundStateDescriptor.class);
             declarePrecedenceOver(ResourceBindingStateDescriptor.class);
-            declareInferiortyTo(CompressionStateDescriptor.class);
+            declareInferiorityTo(CompressionStateDescriptor.class);
         }
 
         @Override

smack-tcp/build.gradle

@@ -3,6 +3,7 @@ Smack for standard XMPP connections over TCP."""
 
 dependencies {
 	compile project(':smack-core')
+	api project(':smack-streammanagement')
 
 	testFixturesApi(testFixtures(project(":smack-core")))
 }

smack-tcp/src/main/java/org/jivesoftware/smack/sm/predicates/tcp/OnceForThisStanza.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2014 Florian Schmaus
+ * Copyright © 2014-2020 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.jivesoftware.smack.sm.predicates;
+package org.jivesoftware.smack.sm.predicates.tcp;
 
 import org.jivesoftware.smack.filter.StanzaFilter;
 import org.jivesoftware.smack.packet.Stanza;

smack-tcp/src/main/java/org/jivesoftware/smack/sm/predicates/tcp/package-info.java

@@ -0,0 +1,21 @@
+/**
+ *
+ * Copyright 2020 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.
+ */
+
+/**
+ * XMPPTCPConnection Stream Managment Predicates.
+ */
+package org.jivesoftware.smack.sm.predicates.tcp;

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

@@ -538,15 +538,24 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
         }
 
         // 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/authenticated/usingTLS to false since we like to behave like we are still
         // connected (e.g. sendStanza should not throw a NotConnectedException).
-        if (isSmResumptionPossible() && instant) {
-            disconnectedButResumeable = true;
+        if (instant) {
+            disconnectedButResumeable = isSmResumptionPossible();
+            if (!disconnectedButResumeable) {
+                // Reset the stream management session id to null, since the stream is no longer resumable. Note that we
+                // keep the unacknowledgedStanzas queue, because we want to resend them when we are reconnected.
+                smSessionId = null;
+            }
         } else {
             disconnectedButResumeable = false;
-            // Reset the stream management session id to null, since if the stream is cleanly closed, i.e. sending a closing
-            // stream tag, there is no longer a stream to resume.
-            smSessionId = null;
+
+            // Drop the stream management state if this is not an instant shutdown. We send
+            // a </stream> close tag and now the stream management state is no longer valid.
+            // This also prevents that we will potentially (re-)send any unavailable presence we
+            // may have send, because it got put into the unacknowledged queue and was not acknowledged before the
+            // connection terminated.
+            dropSmState();
             // Note that we deliberately do not reset authenticatedConnectionInitiallyEstablishedTimestamp here, so that the
             // information is available in the connectionClosedOnError() listeners.
         }
@@ -836,6 +845,8 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
         // there is an error establishing the connection
         connectUsingConfiguration();
 
+        connected = true;
+
         // We connected successfully to the servers TCP port
         initConnection();
 

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

@@ -58,6 +58,7 @@ import org.jivesoftware.smack.XmppInputOutputFilter;
 import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection.ConnectedButUnauthenticatedStateDescriptor;
 import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection.LookupRemoteConnectionEndpointsStateDescriptor;
 import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionModule;
+import org.jivesoftware.smack.c2s.StreamOpenAndCloseFactory;
 import org.jivesoftware.smack.c2s.XmppClientToServerTransport;
 import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
 import org.jivesoftware.smack.c2s.internal.WalkStateGraphContext;
@@ -68,6 +69,7 @@ import org.jivesoftware.smack.fsm.StateTransitionResult;
 import org.jivesoftware.smack.internal.SmackTlsContext;
 import org.jivesoftware.smack.packet.Stanza;
 import org.jivesoftware.smack.packet.StartTls;
+import org.jivesoftware.smack.packet.StreamClose;
 import org.jivesoftware.smack.packet.StreamOpen;
 import org.jivesoftware.smack.packet.TlsFailure;
 import org.jivesoftware.smack.packet.TlsProceed;
@@ -580,6 +582,22 @@ public class XmppTcpTransportModule extends ModularXmppClientToServerConnectionM
             super(connectionInternal);
         }
 
+        @Override
+        public StreamOpenAndCloseFactory getStreamOpenAndCloseFactory() {
+            return new StreamOpenAndCloseFactory() {
+                @Override
+                public StreamOpen createStreamOpen(CharSequence to, CharSequence from, String id, String lang) {
+                    String xmlLang = connectionInternal.connection.getConfiguration().getXmlLang();
+                    StreamOpen streamOpen = new StreamOpen(to, from, id, xmlLang, StreamOpen.StreamContentNamespace.client);
+                    return streamOpen;
+                }
+                @Override
+                public StreamClose createStreamClose() {
+                    return StreamClose.INSTANCE;
+                }
+            };
+        }
+
         @Override
         protected void resetDiscoveredConnectionEndpoints() {
             discoveredTcpEndpoints = null;
@@ -1165,7 +1183,7 @@ public class XmppTcpTransportModule extends ModularXmppClientToServerConnectionM
         }
 
         private void waitForHandshakeFinished() throws InterruptedException, CertificateException, SSLException, SmackException, XMPPException {
-            connectionInternal.waitForCondition(() -> isHandshakeFinished(), "TLS handshake to finish");
+            connectionInternal.waitForConditionOrThrowConnectionException(() -> isHandshakeFinished(), "TLS handshake to finish");
 
             if (handshakeStatus == TlsHandshakeStatus.failed) {
                 throw handshakeException;

smack-websocket/build.gradle

@@ -0,0 +1,10 @@
+description = """\
+Smack for standard XMPP connections over Websockets."""
+
+dependencies {
+	compile project(':smack-core')
+
+	testFixturesApi(testFixtures(project(":smack-core")))
+
+	implementation("com.squareup.okhttp3:okhttp:4.6.0")
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/WebsocketConnectionAttemptState.java

@@ -0,0 +1,101 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.EstablishingWebsocketConnectionState;
+import org.jivesoftware.smack.websocket.implementations.AbstractWebsocket;
+import org.jivesoftware.smack.websocket.implementations.WebsocketImplProvider;
+import org.jivesoftware.smack.websocket.implementations.okhttp.OkHttpWebsocket;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpoint;
+
+public final class WebsocketConnectionAttemptState {
+    private final ModularXmppClientToServerConnectionInternal connectionInternal;
+    private final XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints discoveredEndpoints;
+
+    private WebsocketRemoteConnectionEndpoint connectedEndpoint;
+
+    WebsocketConnectionAttemptState(ModularXmppClientToServerConnectionInternal connectionInternal,
+                    XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints discoveredWebsocketEndpoints,
+                    EstablishingWebsocketConnectionState establishingWebsocketConnectionState) {
+        assert discoveredWebsocketEndpoints != null;
+        this.connectionInternal = connectionInternal;
+        this.discoveredEndpoints = discoveredWebsocketEndpoints;
+    }
+
+    /**
+     * Establish  a websocket connection with one of the discoveredRemoteConnectionEndpoints.<br>
+     *
+     * @return {@link AbstractWebsocket} with which connection is establised
+     * @throws InterruptedException if the calling thread was interrupted
+     * @throws WebsocketException if encounters a websocket exception
+     */
+    AbstractWebsocket establishWebsocketConnection() throws InterruptedException, WebsocketException {
+        List<WebsocketRemoteConnectionEndpoint> endpoints = discoveredEndpoints.result.discoveredRemoteConnectionEndpoints;
+
+        if (endpoints.isEmpty()) {
+            throw new WebsocketException(new Throwable("No Endpoints discovered to establish connection"));
+        }
+
+        List<Throwable> connectionFailureList = new ArrayList<>();
+        AbstractWebsocket websocket;
+
+        try {
+            // Obtain desired websocket implementation by using WebsocketImplProvider
+            websocket = WebsocketImplProvider.getWebsocketImpl(OkHttpWebsocket.class, connectionInternal, discoveredEndpoints);
+        } catch (NoSuchMethodException | SecurityException | InstantiationException |
+                IllegalAccessException | IllegalArgumentException | InvocationTargetException exception) {
+            throw new WebsocketException(exception);
+        }
+
+        // Keep iterating over available endpoints until a connection is establised or all endpoints are tried to create a connection with.
+        for (WebsocketRemoteConnectionEndpoint endpoint : endpoints) {
+            try {
+                websocket.connect(endpoint);
+                connectedEndpoint = endpoint;
+                break;
+            } catch (Throwable t) {
+                connectionFailureList.add(t);
+
+                // If the number of entries in connectionFailureList is equal to the number of endpoints,
+                // it means that all endpoints have been tried and have been unsuccessful.
+                if (connectionFailureList.size() == endpoints.size()) {
+                    WebsocketException websocketException = new WebsocketException(connectionFailureList);
+                    throw new WebsocketException(websocketException);
+                }
+            }
+        }
+
+        assert connectedEndpoint != null;
+
+        // Return connected websocket when no failure occurs.
+        return websocket;
+    }
+
+    /**
+     * Returns the connected websocket endpoint.
+     *
+     * @return connected websocket endpoint
+     */
+    public WebsocketRemoteConnectionEndpoint getConnectedEndpoint() {
+        return connectedEndpoint;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/WebsocketException.java

@@ -0,0 +1,38 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import java.util.Collections;
+import java.util.List;
+
+public final class WebsocketException extends Exception {
+    private static final long serialVersionUID = 1L;
+
+    private final List<Throwable> throwableList;
+
+    public WebsocketException(List<Throwable> throwableList) {
+        this.throwableList = throwableList;
+    }
+
+    public WebsocketException(Throwable throwable) {
+        this.throwableList = Collections.singletonList(throwable);
+    }
+
+    public List<Throwable> getThrowableList() {
+        return throwableList;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/WebsocketInitializer.java

@@ -0,0 +1,28 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import org.jivesoftware.smack.SmackConfiguration;
+import org.jivesoftware.smack.initializer.UrlInitializer;
+
+public final class WebsocketInitializer extends UrlInitializer {
+
+    static {
+        SmackConfiguration.addModule(XmppWebsocketTransportModuleDescriptor.class);
+    }
+
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/XmppWebsocketTransportModule.java

@@ -0,0 +1,325 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import java.io.IOException;
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Queue;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import javax.net.ssl.SSLSession;
+
+import org.jivesoftware.smack.AsyncButOrdered;
+import org.jivesoftware.smack.ConnectionConfiguration.SecurityMode;
+import org.jivesoftware.smack.SmackException;
+import org.jivesoftware.smack.SmackFuture;
+import org.jivesoftware.smack.SmackFuture.InternalSmackFuture;
+import org.jivesoftware.smack.XMPPException;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection.ConnectedButUnauthenticatedStateDescriptor;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection.LookupRemoteConnectionEndpointsStateDescriptor;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionConfiguration;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionModule;
+import org.jivesoftware.smack.c2s.StreamOpenAndCloseFactory;
+import org.jivesoftware.smack.c2s.XmppClientToServerTransport;
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.c2s.internal.WalkStateGraphContext;
+import org.jivesoftware.smack.fsm.State;
+import org.jivesoftware.smack.fsm.StateDescriptor;
+import org.jivesoftware.smack.fsm.StateTransitionResult;
+import org.jivesoftware.smack.fsm.StateTransitionResult.AttemptResult;
+import org.jivesoftware.smack.packet.AbstractStreamClose;
+import org.jivesoftware.smack.packet.AbstractStreamOpen;
+import org.jivesoftware.smack.packet.TopLevelStreamElement;
+import org.jivesoftware.smack.util.StringUtils;
+import org.jivesoftware.smack.util.rce.RemoteConnectionEndpointLookupFailure;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints;
+import org.jivesoftware.smack.websocket.elements.WebsocketCloseElement;
+import org.jivesoftware.smack.websocket.elements.WebsocketOpenElement;
+import org.jivesoftware.smack.websocket.implementations.AbstractWebsocket;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpoint;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpointLookup;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpointLookup.Result;
+
+import org.jxmpp.jid.DomainBareJid;
+import org.jxmpp.jid.impl.JidCreate;
+import org.jxmpp.stringprep.XmppStringprepException;
+
+/**
+ * The websocket transport module that goes with Smack's modular architecture.
+ */
+public final class XmppWebsocketTransportModule
+                extends ModularXmppClientToServerConnectionModule<XmppWebsocketTransportModuleDescriptor> {
+    private final XmppWebsocketTransport websocketTransport;
+
+    private AbstractWebsocket websocket;
+
+    protected XmppWebsocketTransportModule(XmppWebsocketTransportModuleDescriptor moduleDescriptor,
+                    ModularXmppClientToServerConnectionInternal connectionInternal) {
+        super(moduleDescriptor, connectionInternal);
+
+        websocketTransport = new XmppWebsocketTransport(connectionInternal);
+    }
+
+    @Override
+    protected XmppWebsocketTransport getTransport() {
+        return websocketTransport;
+    }
+
+    static final class EstablishingWebsocketConnectionStateDescriptor extends StateDescriptor {
+        private EstablishingWebsocketConnectionStateDescriptor() {
+            super(XmppWebsocketTransportModule.EstablishingWebsocketConnectionState.class);
+            addPredeccessor(LookupRemoteConnectionEndpointsStateDescriptor.class);
+            addSuccessor(ConnectedButUnauthenticatedStateDescriptor.class);
+
+            // This states preference to TCP transports over this Websocket transport implementation.
+            declareInferiorityTo("org.jivesoftware.smack.tcp.XmppTcpTransportModule$EstablishingTcpConnectionStateDescriptor");
+        }
+
+        @Override
+        protected State constructState(ModularXmppClientToServerConnectionInternal connectionInternal) {
+            XmppWebsocketTransportModule websocketTransportModule = connectionInternal.connection.getConnectionModuleFor(
+                            XmppWebsocketTransportModuleDescriptor.class);
+            return websocketTransportModule.constructEstablishingWebsocketConnectionState(this, connectionInternal);
+        }
+    }
+
+    final class EstablishingWebsocketConnectionState extends State {
+        protected EstablishingWebsocketConnectionState(StateDescriptor stateDescriptor,
+                        ModularXmppClientToServerConnectionInternal connectionInternal) {
+            super(stateDescriptor, connectionInternal);
+        }
+
+        @Override
+        public AttemptResult transitionInto(WalkStateGraphContext walkStateGraphContext)
+                        throws IOException, SmackException, InterruptedException, XMPPException {
+            WebsocketConnectionAttemptState connectionAttemptState = new WebsocketConnectionAttemptState(
+                            connectionInternal, discoveredWebsocketEndpoints, this);
+
+            try {
+                websocket = connectionAttemptState.establishWebsocketConnection();
+            } catch (InterruptedException | WebsocketException e) {
+                StateTransitionResult.Failure failure = new StateTransitionResult.FailureCausedByException<Exception>(e);
+                return failure;
+            }
+
+            connectionInternal.setTransport(websocketTransport);
+
+            WebsocketRemoteConnectionEndpoint connectedEndpoint = connectionAttemptState.getConnectedEndpoint();
+
+            // Construct a WebsocketConnectedResult using the connected endpoint.
+            return new WebsocketConnectedResult(connectedEndpoint);
+        }
+    }
+
+    public EstablishingWebsocketConnectionState constructEstablishingWebsocketConnectionState(
+                    EstablishingWebsocketConnectionStateDescriptor establishingWebsocketConnectionStateDescriptor,
+                    ModularXmppClientToServerConnectionInternal connectionInternal) {
+        return new EstablishingWebsocketConnectionState(establishingWebsocketConnectionStateDescriptor,
+                        connectionInternal);
+    }
+
+    public static final class WebsocketConnectedResult extends StateTransitionResult.Success {
+        final WebsocketRemoteConnectionEndpoint connectedEndpoint;
+
+        public WebsocketConnectedResult(WebsocketRemoteConnectionEndpoint connectedEndpoint) {
+            super("Websocket connection establised with endpoint: " + connectedEndpoint.getWebsocketEndpoint());
+            this.connectedEndpoint = connectedEndpoint;
+        }
+    }
+
+    private DiscoveredWebsocketEndpoints discoveredWebsocketEndpoints;
+
+    /**
+     * Transport class for {@link ModularXmppClientToServerConnectionModule}'s websocket implementation.
+     */
+    public final class XmppWebsocketTransport extends XmppClientToServerTransport {
+
+        AsyncButOrdered<Queue<TopLevelStreamElement>> asyncButOrderedOutgoingElementsQueue;
+
+        protected XmppWebsocketTransport(ModularXmppClientToServerConnectionInternal connectionInternal) {
+            super(connectionInternal);
+            asyncButOrderedOutgoingElementsQueue = new AsyncButOrdered<Queue<TopLevelStreamElement>>();
+        }
+
+        @Override
+        protected void resetDiscoveredConnectionEndpoints() {
+            discoveredWebsocketEndpoints = null;
+        }
+
+        @Override
+        protected List<SmackFuture<LookupConnectionEndpointsResult, Exception>> lookupConnectionEndpoints() {
+            // Assert that there are no stale discovered endpoints prior performing the lookup.
+            assert discoveredWebsocketEndpoints == null;
+
+            InternalSmackFuture<LookupConnectionEndpointsResult, Exception> websocketEndpointsLookupFuture = new InternalSmackFuture<>();
+
+            connectionInternal.asyncGo(() -> {
+
+                WebsocketRemoteConnectionEndpoint providedEndpoint = null;
+
+                // Check if there is a websocket endpoint already configured.
+                URI uri = moduleDescriptor.getExplicitlyProvidedUri();
+                if (uri != null) {
+                    providedEndpoint = new WebsocketRemoteConnectionEndpoint(uri);
+                }
+
+                if (!moduleDescriptor.isWebsocketEndpointDiscoveryEnabled()) {
+                    // If discovery is disabled, assert that the provided endpoint isn't null.
+                    assert providedEndpoint != null;
+
+                    SecurityMode mode = connectionInternal.connection.getConfiguration().getSecurityMode();
+                    if ((providedEndpoint.isSecureEndpoint() &&
+                            mode.equals(SecurityMode.disabled))
+                            || (!providedEndpoint.isSecureEndpoint() &&
+                                    mode.equals(SecurityMode.required))) {
+                        throw new IllegalStateException("Explicitly configured uri: " + providedEndpoint.getWebsocketEndpoint().toString()
+                                + " does not comply with the configured security mode: " + mode);
+                    }
+
+                    // Generate Result for explicitly configured endpoint.
+                    Result manualResult = new Result(Arrays.asList(providedEndpoint), null);
+
+                    LookupConnectionEndpointsResult endpointsResult = new DiscoveredWebsocketEndpoints(manualResult);
+
+                    websocketEndpointsLookupFuture.setResult(endpointsResult);
+                } else {
+                    DomainBareJid host = connectionInternal.connection.getXMPPServiceDomain();
+                    ModularXmppClientToServerConnectionConfiguration configuration = connectionInternal.connection.getConfiguration();
+                    SecurityMode mode = configuration.getSecurityMode();
+
+                    // Fetch remote endpoints.
+                    Result xep0156result = WebsocketRemoteConnectionEndpointLookup.lookup(host, mode);
+
+                    List<WebsocketRemoteConnectionEndpoint> discoveredEndpoints = xep0156result.discoveredRemoteConnectionEndpoints;
+
+                    // Generate result considering both manual and fetched endpoints.
+                    Result finalResult = new Result(discoveredEndpoints, xep0156result.getLookupFailures());
+
+                    LookupConnectionEndpointsResult endpointsResult = new DiscoveredWebsocketEndpoints(finalResult);
+
+                    websocketEndpointsLookupFuture.setResult(endpointsResult);
+                }
+            });
+
+            return Collections.singletonList(websocketEndpointsLookupFuture);
+        }
+
+        @Override
+        protected void loadConnectionEndpoints(LookupConnectionEndpointsSuccess lookupConnectionEndpointsSuccess) {
+            discoveredWebsocketEndpoints = (DiscoveredWebsocketEndpoints) lookupConnectionEndpointsSuccess;
+        }
+
+        @Override
+        protected void afterFiltersClosed() {
+        }
+
+        @Override
+        protected void disconnect() {
+            websocket.disconnect(1000, "Websocket closed normally");
+        }
+
+        @Override
+        protected void notifyAboutNewOutgoingElements() {
+            Queue<TopLevelStreamElement> outgoingElementsQueue = connectionInternal.outgoingElementsQueue;
+            asyncButOrderedOutgoingElementsQueue.performAsyncButOrdered(outgoingElementsQueue, () -> {
+                // Once new outgoingElement is notified, send the top level stream element obtained by polling.
+                TopLevelStreamElement topLevelStreamElement = outgoingElementsQueue.poll();
+                websocket.send(topLevelStreamElement);
+            });
+        }
+
+        @Override
+        public SSLSession getSslSession() {
+           return websocket.getSSLSession();
+        }
+
+        @Override
+        public boolean isTransportSecured() {
+            return websocket.isConnectionSecure();
+        }
+
+        @Override
+        public boolean isConnected() {
+            return websocket.isConnected();
+        }
+
+        @Override
+        public Stats getStats() {
+            return null;
+        }
+
+        @Override
+        public StreamOpenAndCloseFactory getStreamOpenAndCloseFactory() {
+            return new StreamOpenAndCloseFactory() {
+                @Override
+                public AbstractStreamOpen createStreamOpen(CharSequence to, CharSequence from, String id, String lang) {
+                    try {
+                        return new WebsocketOpenElement(JidCreate.domainBareFrom(to));
+                    } catch (XmppStringprepException e) {
+                        Logger.getAnonymousLogger().log(Level.WARNING, "Couldn't create OpenElement", e);
+                        return null;
+                    }
+                }
+                @Override
+                public AbstractStreamClose createStreamClose() {
+                    return new WebsocketCloseElement();
+                }
+            };
+        }
+
+        /**
+         * Contains {@link Result} for successfully discovered endpoints.
+         */
+        public final class DiscoveredWebsocketEndpoints implements LookupConnectionEndpointsSuccess {
+            final WebsocketRemoteConnectionEndpointLookup.Result result;
+
+            DiscoveredWebsocketEndpoints(Result result) {
+                assert result != null;
+                this.result = result;
+            }
+
+            public WebsocketRemoteConnectionEndpointLookup.Result getResult() {
+                return result;
+            }
+        }
+
+        /**
+         * Contains list of {@link RemoteConnectionEndpointLookupFailure} when no endpoint
+         * could be found during http lookup.
+         */
+        final class WebsocketEndpointsDiscoveryFailed implements LookupConnectionEndpointsFailed {
+            final List<RemoteConnectionEndpointLookupFailure> lookupFailures;
+
+            WebsocketEndpointsDiscoveryFailed(
+                            WebsocketRemoteConnectionEndpointLookup.Result result) {
+                assert result != null;
+                lookupFailures = Collections.unmodifiableList(result.lookupFailures);
+            }
+
+            @Override
+            public String toString() {
+                StringBuilder str = new StringBuilder();
+                StringUtils.appendTo(lookupFailures, str);
+                return str.toString();
+            }
+        }
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/XmppWebsocketTransportModuleDescriptor.java

@@ -0,0 +1,136 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionConfiguration;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionModule;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionModuleDescriptor;
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.fsm.StateDescriptor;
+import org.jivesoftware.smack.util.Objects;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.EstablishingWebsocketConnectionStateDescriptor;
+
+/**
+ * The descriptor class for {@link XmppWebsocketTransportModule}.
+ * <br>
+ * To add {@link XmppWebsocketTransportModule} to {@link ModularXmppClientToServerConnection},
+ * use {@link ModularXmppClientToServerConnectionConfiguration.Builder#addModule(ModularXmppClientToServerConnectionModuleDescriptor)}.
+ */
+public final class XmppWebsocketTransportModuleDescriptor extends ModularXmppClientToServerConnectionModuleDescriptor {
+    private boolean performWebsocketEndpointDiscovery;
+    private URI uri;
+
+    public XmppWebsocketTransportModuleDescriptor(Builder builder) {
+        this.performWebsocketEndpointDiscovery = builder.performWebsocketEndpointDiscovery;
+        this.uri = builder.uri;
+    }
+
+    /**
+     * Returns true if websocket endpoint discovery is true, returns false otherwise.
+     * @return boolean
+     */
+    public boolean isWebsocketEndpointDiscoveryEnabled() {
+        return performWebsocketEndpointDiscovery;
+    }
+
+    /**
+     * Returns explicitly configured websocket endpoint uri.
+     * @return uri
+     */
+    public URI getExplicitlyProvidedUri() {
+        return uri;
+    }
+
+    @Override
+    protected Set<Class<? extends StateDescriptor>> getStateDescriptors() {
+        Set<Class<? extends StateDescriptor>> res = new HashSet<>();
+        res.add(EstablishingWebsocketConnectionStateDescriptor.class);
+        return res;
+    }
+
+    @Override
+    protected ModularXmppClientToServerConnectionModule<? extends ModularXmppClientToServerConnectionModuleDescriptor> constructXmppConnectionModule(
+            ModularXmppClientToServerConnectionInternal connectionInternal) {
+        return new XmppWebsocketTransportModule(this, connectionInternal);
+    }
+
+    /**
+     * Returns a new instance of {@link Builder}.
+     * <br>
+     * @return Builder
+     * @param connectionConfigurationBuilder {@link ModularXmppClientToServerConnectionConfiguration.Builder}.
+     */
+    public static Builder getBuilder(
+            ModularXmppClientToServerConnectionConfiguration.Builder connectionConfigurationBuilder) {
+        return new Builder(connectionConfigurationBuilder);
+    }
+
+    /**
+     * Builder class for {@link XmppWebsocketTransportModuleDescriptor}.
+     * <br>
+     * To obtain an instance of {@link XmppWebsocketTransportModuleDescriptor.Builder}, use {@link XmppWebsocketTransportModuleDescriptor#getBuilder(ModularXmppClientToServerConnectionConfiguration.Builder)} method.
+     * <br>
+     * Use {@link Builder#explicitlySetWebsocketEndpoint(URI)} to configure the URI of an endpoint as a backup in case connection couldn't be established with endpoints through http lookup.
+     * <br>
+     * Use {@link Builder#explicitlySetWebsocketEndpointAndDiscovery(URI, boolean)} to configure endpoint and disallow websocket endpoint discovery through http lookup.
+     * By default, {@link Builder#performWebsocketEndpointDiscovery} is set to true.
+     * <br>
+     * Use {@link Builder#build()} to obtain {@link XmppWebsocketTransportModuleDescriptor}.
+     */
+    public static final class Builder extends ModularXmppClientToServerConnectionModuleDescriptor.Builder {
+        private boolean performWebsocketEndpointDiscovery = true;
+        private URI uri;
+
+        private Builder(
+                ModularXmppClientToServerConnectionConfiguration.Builder connectionConfigurationBuilder) {
+            super(connectionConfigurationBuilder);
+        }
+
+        public Builder explicitlySetWebsocketEndpoint(URI endpoint) {
+            return explicitlySetWebsocketEndpointAndDiscovery(endpoint, true);
+        }
+
+        public Builder explicitlySetWebsocketEndpointAndDiscovery(URI endpoint, boolean performWebsocketEndpointDiscovery) {
+            Objects.requireNonNull(endpoint, "Provided endpoint URI must not be null");
+            this.uri = endpoint;
+            this.performWebsocketEndpointDiscovery = performWebsocketEndpointDiscovery;
+            return this;
+        }
+
+        public Builder explicitlySetWebsocketEndpoint(CharSequence endpoint) throws URISyntaxException {
+            URI endpointUri = new URI(endpoint.toString());
+            return explicitlySetWebsocketEndpointAndDiscovery(endpointUri, true);
+        }
+
+        public Builder explicitlySetWebsocketEndpoint(CharSequence endpoint, boolean performWebsocketEndpointDiscovery)
+                throws URISyntaxException {
+            URI endpointUri = new URI(endpoint.toString());
+            return explicitlySetWebsocketEndpointAndDiscovery(endpointUri, performWebsocketEndpointDiscovery);
+        }
+
+        @Override
+        public ModularXmppClientToServerConnectionModuleDescriptor build() {
+            return new XmppWebsocketTransportModuleDescriptor(this);
+        }
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/elements/AbstractWebsocketNonza.java

@@ -0,0 +1,47 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.elements;
+
+import org.jivesoftware.smack.packet.Nonza;
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+
+import org.jxmpp.jid.DomainBareJid;
+
+public abstract class AbstractWebsocketNonza implements Nonza {
+    public static final String NAMESPACE = "urn:ietf:params:xml:ns:xmpp-framing";
+    private static final String VERSION = "1.0";
+    private final DomainBareJid to;
+
+    public AbstractWebsocketNonza(DomainBareJid jid) {
+        this.to = jid;
+    }
+
+    @Override
+    public String getNamespace() {
+        return NAMESPACE;
+    }
+
+    @Override
+    public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
+        XmlStringBuilder xml = new XmlStringBuilder(this, xmlEnvironment);
+        xml.attribute("to", to.toString());
+        xml.attribute("version", VERSION);
+        xml.closeEmptyElement();
+        return xml;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/elements/WebsocketCloseElement.java

@@ -0,0 +1,49 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.elements;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.AbstractStreamClose;
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+
+public final class WebsocketCloseElement extends AbstractStreamClose {
+    public static final String ELEMENT = "close";
+    public static final String NAMESPACE = "urn:ietf:params:xml:ns:xmpp-framing";
+    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
+    public WebsocketCloseElement() {
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public String getNamespace() {
+        return NAMESPACE;
+    }
+
+    @Override
+    public CharSequence toXML(XmlEnvironment xmlEnvironment) {
+        XmlStringBuilder xml = new XmlStringBuilder(this);
+        xml.closeEmptyElement();
+        return xml;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/elements/WebsocketOpenElement.java

@@ -0,0 +1,54 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.elements;
+
+import javax.xml.namespace.QName;
+
+import org.jivesoftware.smack.packet.AbstractStreamOpen;
+import org.jivesoftware.smack.packet.StreamOpen.StreamContentNamespace;
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+
+import org.jxmpp.jid.DomainBareJid;
+
+public final class WebsocketOpenElement extends AbstractStreamOpen {
+    public static final String ELEMENT = "open";
+    public static final String NAMESPACE = "urn:ietf:params:xml:ns:xmpp-framing";
+    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);
+
+    public WebsocketOpenElement(DomainBareJid to) {
+        super(to, null, null, null, StreamContentNamespace.client);
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public String getNamespace() {
+        return NAMESPACE;
+    }
+
+    @Override
+    public CharSequence toXML(XmlEnvironment xmlEnvironment) {
+        XmlStringBuilder xml = new XmlStringBuilder(this);
+        addCommonAttributes(xml);
+        xml.closeEmptyElement();
+        return xml;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/elements/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.
+ */
+/**
+ * This package contains Stanzas required to open and close stream.
+ */
+package org.jivesoftware.smack.websocket.elements;

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/implementations/AbstractWebsocket.java

@@ -0,0 +1,63 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar.
+ *
+ * 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.websocket.implementations;
+
+import javax.net.ssl.SSLSession;
+
+import org.jivesoftware.smack.packet.TopLevelStreamElement;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpoint;
+
+public abstract class AbstractWebsocket {
+
+    protected enum WebsocketConnectionPhase {
+        openFrameSent,
+        exchangingTopLevelStreamElements
+    }
+
+    protected static String getStreamFromOpenElement(String openElement) {
+        String streamElement = openElement.replaceFirst("\\A<open ", "<stream ")
+                                          .replace("urn:ietf:params:xml:ns:xmpp-framing", "jabber:client")
+                                          .replaceFirst("/>\\s*\\z", ">");
+        return streamElement;
+    }
+
+    protected static boolean isOpenElement(String text) {
+        if (text.startsWith("<open ")) {
+            return true;
+        }
+        return false;
+    }
+
+    protected static boolean isCloseElement(String text) {
+        if (text.startsWith("<close xmlns='urn:ietf:params:xml:ns:xmpp-framing'/>")) {
+            return true;
+        }
+        return false;
+    }
+
+    public abstract void connect(WebsocketRemoteConnectionEndpoint endpoint) throws Throwable;
+
+    public abstract void send(TopLevelStreamElement element);
+
+    public abstract void disconnect(int code, String message);
+
+    public abstract boolean isConnectionSecure();
+
+    public abstract SSLSession getSSLSession();
+
+    public abstract boolean isConnected();
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/implementations/WebsocketImplProvider.java

@@ -0,0 +1,35 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar.
+ *
+ * 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.websocket.implementations;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.util.Objects;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints;
+
+public final class WebsocketImplProvider {
+
+    public static AbstractWebsocket getWebsocketImpl(Class<? extends AbstractWebsocket> websocketImpl, ModularXmppClientToServerConnectionInternal connectionInternal, DiscoveredWebsocketEndpoints discoveredWebsocketEndpoints) throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
+        Objects.requireNonNull(connectionInternal, "ConnectionInternal cannot be null");
+
+        // Creates an instance of the constructor for the desired websocket implementation.
+        Constructor<? extends AbstractWebsocket> constructor = websocketImpl.getConstructor(ModularXmppClientToServerConnectionInternal.class, DiscoveredWebsocketEndpoints.class);
+        return (AbstractWebsocket) constructor.newInstance(connectionInternal, discoveredWebsocketEndpoints);
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/implementations/okhttp/LoggingInterceptor.java

@@ -0,0 +1,90 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.implementations.okhttp;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.Iterator;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import org.jivesoftware.smack.debugger.SmackDebugger;
+
+import okhttp3.Headers;
+import okhttp3.Response;
+
+import org.jxmpp.xml.splitter.Utf8ByteXmppXmlSplitter;
+import org.jxmpp.xml.splitter.XmlPrettyPrinter;
+import org.jxmpp.xml.splitter.XmppXmlSplitter;
+
+public final class LoggingInterceptor {
+    private static final Logger LOGGER = Logger.getAnonymousLogger();
+    private static final int MAX_ELEMENT_SIZE = 64 * 1024;
+    private final SmackDebugger debugger;
+    private final Utf8ByteXmppXmlSplitter incomingTextSplitter;
+    private final Utf8ByteXmppXmlSplitter outgoingTextSplitter;
+
+    public LoggingInterceptor(SmackDebugger smackDebugger) {
+        this.debugger = smackDebugger;
+
+        XmlPrettyPrinter incomingTextPrinter = XmlPrettyPrinter.builder()
+                                    .setPrettyWriter(sb -> debugger.incomingStreamSink(sb))
+                                    .setTabWidth(4)
+                                    .build();
+        XmppXmlSplitter incomingXmlSplitter = new XmppXmlSplitter(MAX_ELEMENT_SIZE, null,
+                incomingTextPrinter);
+        incomingTextSplitter = new Utf8ByteXmppXmlSplitter(incomingXmlSplitter);
+
+        XmlPrettyPrinter outgoingTextPrinter = XmlPrettyPrinter.builder()
+                .setPrettyWriter(sb -> debugger.outgoingStreamSink(sb))
+                .setTabWidth(4)
+                .build();
+        XmppXmlSplitter outgoingXmlSplitter = new XmppXmlSplitter(MAX_ELEMENT_SIZE, null,
+                outgoingTextPrinter);
+        outgoingTextSplitter = new Utf8ByteXmppXmlSplitter(outgoingXmlSplitter);
+    }
+
+    // Open response received here isn't in the form of an Xml an so, there isn't much to format.
+    public void interceptOpenResponse(Response response) {
+       Headers headers = response.headers();
+       Iterator<?> iterator = headers.iterator();
+       StringBuilder sb = new StringBuilder();
+       sb.append("Received headers:");
+       while (iterator.hasNext()) {
+           sb.append("\n\t" + iterator.next());
+       }
+       debugger.incomingStreamSink(sb);
+    }
+
+    public void interceptReceivedText(String text) {
+        try {
+            incomingTextSplitter.write(text.getBytes(Charset.defaultCharset()));
+        } catch (IOException e) {
+            // Connections shouldn't be terminated due to exceptions encountered during debugging. hence only log them.
+            LOGGER.log(Level.WARNING, "IOException encountered while parsing received text: " + text, e);
+        }
+    }
+
+    public void interceptSentText(String text) {
+        try {
+            outgoingTextSplitter.write(text.getBytes(Charset.defaultCharset()));
+        } catch (IOException e) {
+            // Connections shouldn't be terminated due to exceptions encountered during debugging, hence only log them.
+            LOGGER.log(Level.WARNING, "IOException encountered while parsing outgoing text: " + text, e);
+        }
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/implementations/okhttp/OkHttpWebsocket.java

@@ -0,0 +1,179 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.implementations.okhttp;
+
+import java.io.IOException;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import javax.net.ssl.SSLSession;
+
+import org.jivesoftware.smack.SmackException;
+import org.jivesoftware.smack.XMPPException;
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.packet.TopLevelStreamElement;
+import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.websocket.WebsocketException;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints;
+import org.jivesoftware.smack.websocket.elements.WebsocketOpenElement;
+import org.jivesoftware.smack.websocket.implementations.AbstractWebsocket;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpoint;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+import okhttp3.WebSocket;
+import okhttp3.WebSocketListener;
+
+public final class OkHttpWebsocket extends AbstractWebsocket {
+
+    private static final Logger LOGGER = Logger.getLogger(OkHttpWebsocket.class.getName());
+
+    private static OkHttpClient okHttpClient = null;
+
+    private final ModularXmppClientToServerConnectionInternal connectionInternal;
+    private final LoggingInterceptor interceptor;
+
+    private String openStreamHeader;
+    private WebSocket currentWebsocket;
+    private WebsocketConnectionPhase phase;
+    private WebsocketRemoteConnectionEndpoint connectedEndpoint;
+
+    public OkHttpWebsocket(ModularXmppClientToServerConnectionInternal connectionInternal,
+            DiscoveredWebsocketEndpoints discoveredWebsocketEndpoints) {
+        this.connectionInternal = connectionInternal;
+
+        if (okHttpClient == null) {
+            // Creates an instance of okHttp client.
+            OkHttpClient.Builder builder = new OkHttpClient.Builder();
+            okHttpClient = builder.build();
+        }
+        // Add some mechanism to enable and disable this interceptor.
+        if (connectionInternal.smackDebugger != null) {
+            interceptor = new LoggingInterceptor(connectionInternal.smackDebugger);
+        } else {
+            interceptor = null;
+        }
+    }
+
+    @Override
+    public void connect(WebsocketRemoteConnectionEndpoint endpoint) throws InterruptedException, SmackException, XMPPException {
+        final String currentUri = endpoint.getWebsocketEndpoint().toString();
+        Request request = new Request.Builder()
+                              .url(currentUri)
+                              .header("Sec-WebSocket-Protocol", "xmpp")
+                              .build();
+
+        WebSocketListener listener = new WebSocketListener() {
+
+            @Override
+            public void onOpen(WebSocket webSocket, Response response) {
+                LOGGER.log(Level.FINER, "Websocket is open");
+                phase = WebsocketConnectionPhase.openFrameSent;
+                if (interceptor != null) {
+                    interceptor.interceptOpenResponse(response);
+                }
+                send(new WebsocketOpenElement(connectionInternal.connection.getXMPPServiceDomain()));
+            }
+
+            @Override
+            public void onMessage(WebSocket webSocket, String text) {
+                if (interceptor != null) {
+                    interceptor.interceptReceivedText(text);
+                }
+                if (isCloseElement(text)) {
+                    connectionInternal.onStreamClosed();
+                    return;
+                }
+
+                String closingStream = "</stream>";
+                switch (phase) {
+                case openFrameSent:
+                    if (isOpenElement(text)) {
+                        // Converts the <open> element received into <stream> element.
+                        openStreamHeader = getStreamFromOpenElement(text);
+                        phase = WebsocketConnectionPhase.exchangingTopLevelStreamElements;
+
+                        try {
+                            connectionInternal.onStreamOpen(PacketParserUtils.getParserFor(openStreamHeader));
+                        } catch (XmlPullParserException | IOException e) {
+                            LOGGER.log(Level.WARNING, "Exception caught:", e);
+                        }
+                    } else {
+                        LOGGER.log(Level.WARNING, "Unexpected Frame received", text);
+                    }
+                    break;
+                case exchangingTopLevelStreamElements:
+                    connectionInternal.parseAndProcessElement(openStreamHeader + text + closingStream);
+                    break;
+                default:
+                    LOGGER.log(Level.INFO, "Default text: " + text);
+                }
+            }
+
+            @Override
+            public void onFailure(WebSocket webSocket, Throwable t, Response response) {
+                LOGGER.log(Level.INFO, "Exception caught", t);
+                WebsocketException websocketException = new WebsocketException(t);
+                if (connectionInternal.connection.isConnected()) {
+                    connectionInternal.notifyConnectionError(websocketException);
+                } else {
+                    connectionInternal.setCurrentConnectionExceptionAndNotify(websocketException);
+                }
+            }
+        };
+
+        // Creates an instance of websocket through okHttpClient.
+        currentWebsocket = okHttpClient.newWebSocket(request, listener);
+
+        // Open a new stream and wait until features are received.
+        connectionInternal.waitForFeaturesReceived("Waiting to receive features");
+
+        connectedEndpoint = endpoint;
+    }
+
+    @Override
+    public void send(TopLevelStreamElement element) {
+        String textToBeSent = element.toXML().toString();
+        if (interceptor != null) {
+            interceptor.interceptSentText(textToBeSent);
+        }
+        currentWebsocket.send(textToBeSent);
+    }
+
+    @Override
+    public void disconnect(int code, String message) {
+        currentWebsocket.close(code, message);
+        LOGGER.log(Level.INFO, "Websocket has been closed with message: " + message);
+    }
+
+    @Override
+    public boolean isConnectionSecure() {
+        return connectedEndpoint.isSecureEndpoint();
+    }
+
+    @Override
+    public boolean isConnected() {
+        return connectedEndpoint == null ? false : true;
+    }
+
+    @Override
+    public SSLSession getSSLSession() {
+        return null;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/implementations/okhttp/package-info.java

@@ -0,0 +1,17 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.implementations.okhttp;

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/implementations/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.
+ */
+/**
+ * This package contains websocket implementations to be plugged inside websocket transport.
+ */
+package org.jivesoftware.smack.websocket.implementations;

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.
+ */
+/**
+ * Websocket related classes for Smack.
+ */
+package org.jivesoftware.smack.websocket;

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/rce/WebsocketRemoteConnectionEndpoint.java

@@ -0,0 +1,85 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.rce;
+
+import java.net.InetAddress;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.UnknownHostException;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import org.jivesoftware.smack.datatypes.UInt16;
+import org.jivesoftware.smack.util.rce.RemoteConnectionEndpoint;
+
+public final class WebsocketRemoteConnectionEndpoint implements RemoteConnectionEndpoint {
+
+    private static final Logger LOGGER = Logger.getAnonymousLogger();
+
+    private final URI uri;
+
+    public WebsocketRemoteConnectionEndpoint(String uri) throws URISyntaxException {
+        this(new URI(uri));
+    }
+
+    public WebsocketRemoteConnectionEndpoint(URI uri) {
+        this.uri = uri;
+        String scheme = uri.getScheme();
+        if (!(scheme.equals("ws") || scheme.equals("wss"))) {
+            throw new IllegalArgumentException("Only allowed protocols are ws and wss");
+        }
+    }
+
+    public URI getWebsocketEndpoint() {
+        return uri;
+    }
+
+    public boolean isSecureEndpoint() {
+        if (uri.getScheme().equals("wss")) {
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public CharSequence getHost() {
+        return uri.getHost();
+    }
+
+    @Override
+    public UInt16 getPort() {
+        return UInt16.from(uri.getPort());
+    }
+
+    @Override
+    public Collection<? extends InetAddress> getInetAddresses() {
+        try {
+            InetAddress address = InetAddress.getByName(getHost().toString());
+            return Collections.singletonList(address);
+        } catch (UnknownHostException e) {
+            LOGGER.log(Level.INFO, "Unknown Host Exception ", e);
+        }
+        return null;
+    }
+
+    @Override
+    public String getDescription() {
+        return null;
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/rce/WebsocketRemoteConnectionEndpointLookup.java

@@ -0,0 +1,115 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.rce;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import org.jivesoftware.smack.ConnectionConfiguration.SecurityMode;
+import org.jivesoftware.smack.altconnections.HttpLookupMethod;
+import org.jivesoftware.smack.altconnections.HttpLookupMethod.LinkRelation;
+import org.jivesoftware.smack.util.rce.RemoteConnectionEndpointLookupFailure;
+import org.jivesoftware.smack.xml.XmlPullParserException;
+
+import org.jxmpp.jid.DomainBareJid;
+
+public final class WebsocketRemoteConnectionEndpointLookup {
+
+    public static Result lookup(DomainBareJid domainBareJid, SecurityMode securityMode) {
+        List<RemoteConnectionEndpointLookupFailure> lookupFailures = new ArrayList<>(1);
+        List<WebsocketRemoteConnectionEndpoint> discoveredRemoteConnectionEndpoints = new ArrayList<>();
+
+        List<URI> rcUriList = null;
+        try {
+            // Look for remote connection endpoints by making use of http lookup method described inside XEP-0156.
+            rcUriList = HttpLookupMethod.lookup(domainBareJid,
+                            LinkRelation.WEBSOCKET);
+        } catch (IOException | XmlPullParserException | URISyntaxException e) {
+            lookupFailures.add(new RemoteConnectionEndpointLookupFailure.HttpLookupFailure(
+                            domainBareJid, e));
+            return new Result(discoveredRemoteConnectionEndpoints, lookupFailures);
+        }
+
+        if (rcUriList.isEmpty()) {
+            throw new IllegalStateException("No endpoints were found inside host-meta");
+        }
+
+        // Convert rcUriList to List<WebsocketRemoteConnectionEndpoint>
+        Iterator<URI> iterator = rcUriList.iterator();
+        List<WebsocketRemoteConnectionEndpoint> rceList = new ArrayList<>();
+        while (iterator.hasNext()) {
+            rceList.add(new WebsocketRemoteConnectionEndpoint(iterator.next()));
+        }
+
+        switch (securityMode) {
+            case ifpossible:
+                // If security mode equals `if-possible`, give priority to secure endpoints over insecure endpoints.
+
+                // Seprate secure and unsecure endpoints.
+                List<WebsocketRemoteConnectionEndpoint> secureEndpointsForSecurityModeIfPossible = new ArrayList<>();
+                List<WebsocketRemoteConnectionEndpoint> insecureEndpointsForSecurityModeIfPossible = new ArrayList<>();
+                for (WebsocketRemoteConnectionEndpoint uri : rceList) {
+                    if (uri.isSecureEndpoint()) {
+                        secureEndpointsForSecurityModeIfPossible.add(uri);
+                    } else {
+                        insecureEndpointsForSecurityModeIfPossible.add(uri);
+                    }
+                }
+                discoveredRemoteConnectionEndpoints = secureEndpointsForSecurityModeIfPossible;
+                discoveredRemoteConnectionEndpoints.addAll(insecureEndpointsForSecurityModeIfPossible);
+                break;
+            case required:
+            case disabled:
+                /**
+                 * If, SecurityMode equals to required, accept wss endpoints (secure endpoints) only or,
+                 * if SecurityMode equals to disabled, accept ws endpoints (unsecure endpoints) only.
+                 */
+                for (WebsocketRemoteConnectionEndpoint uri : rceList) {
+                    if ((securityMode.equals(SecurityMode.disabled) && !uri.isSecureEndpoint())
+                                    || (securityMode.equals(SecurityMode.required) && uri.isSecureEndpoint())) {
+                        discoveredRemoteConnectionEndpoints.add(uri);
+                    }
+                }
+                break;
+            default:
+        }
+        return new Result(discoveredRemoteConnectionEndpoints, lookupFailures);
+    }
+
+    public static final class Result {
+        public final List<WebsocketRemoteConnectionEndpoint> discoveredRemoteConnectionEndpoints;
+        public final List<RemoteConnectionEndpointLookupFailure> lookupFailures;
+
+        public Result(List<WebsocketRemoteConnectionEndpoint> discoveredRemoteConnectionEndpoints,
+                        List<RemoteConnectionEndpointLookupFailure> lookupFailures) {
+            this.discoveredRemoteConnectionEndpoints = discoveredRemoteConnectionEndpoints;
+            this.lookupFailures = lookupFailures;
+        }
+
+        public List<WebsocketRemoteConnectionEndpoint> getDiscoveredRemoteConnectionEndpoints() {
+            return discoveredRemoteConnectionEndpoints;
+        }
+
+        public List<RemoteConnectionEndpointLookupFailure> getLookupFailures() {
+            return lookupFailures;
+        }
+    }
+}

smack-websocket/src/main/java/org/jivesoftware/smack/websocket/rce/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.
+ */
+/**
+ * This package contains websocket endpoint classes needed by the websocket transport.
+ */
+package org.jivesoftware.smack.websocket.rce;

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/WebsocketConnectionAttemptStateTest.java

@@ -0,0 +1,28 @@
+/**
+ *
+  * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class WebsocketConnectionAttemptStateTest {
+    @Test
+    public void constructorTest() {
+        assertThrows(AssertionError.class, () -> new WebsocketConnectionAttemptState(null, null, null));
+    }
+}

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/WebsocketInitializerTest.java

@@ -0,0 +1,32 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class WebsocketInitializerTest {
+    @Test
+    public void testExtensionInitializer() {
+        WebsocketInitializer initializer = new WebsocketInitializer();
+        List<Exception> exceptions = initializer.initialize();
+        assertTrue(exceptions.size() == 0);
+    }
+}

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/XmppWebsocketTransportModuleTest.java

@@ -0,0 +1,124 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import static org.mockito.Mockito.mock;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnection;
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionConfiguration;
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.util.rce.RemoteConnectionEndpointLookupFailure;
+import org.jivesoftware.smack.util.rce.RemoteConnectionEndpointLookupFailure.HttpLookupFailure;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.XmppWebsocketTransport.WebsocketEndpointsDiscoveryFailed;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpoint;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpointLookup.Result;
+
+import org.junit.jupiter.api.Test;
+import org.jxmpp.stringprep.XmppStringprepException;
+
+public class XmppWebsocketTransportModuleTest {
+    @Test
+    public void createWebsocketModuleConnectionInstanceTest() throws URISyntaxException, XmppStringprepException {
+        ModularXmppClientToServerConnectionConfiguration.Builder builder = ModularXmppClientToServerConnectionConfiguration
+                .builder();
+
+        builder.removeAllModules();
+        builder.addModule(XmppWebsocketTransportModuleDescriptor.class);
+        builder.setXmppAddressAndPassword("user5@localhost.org", "user5");
+        builder.setHost("localhost.org");
+
+        XmppWebsocketTransportModuleDescriptor.Builder websocketBuilder = XmppWebsocketTransportModuleDescriptor.getBuilder(builder);
+        websocketBuilder.explicitlySetWebsocketEndpointAndDiscovery(new URI("wss://localhost.org:7443/ws/"), false);
+
+        ModularXmppClientToServerConnectionConfiguration config = builder.build();
+        ModularXmppClientToServerConnection connection = new ModularXmppClientToServerConnection(config);
+        assertNotNull(connection);
+    }
+
+    @Test
+    public void createDescriptorTest() throws URISyntaxException, XmppStringprepException {
+        XmppWebsocketTransportModuleDescriptor websocketTransportModuleDescriptor = getWebsocketDescriptor();
+        assertNotNull(websocketTransportModuleDescriptor);
+    }
+
+    @Test
+    public void websocketEndpointDiscoveryTest() throws URISyntaxException {
+        XmppWebsocketTransportModuleDescriptor websocketTransportModuleDescriptor = getWebsocketDescriptor();
+        ModularXmppClientToServerConnectionInternal connectionInternal = mock(ModularXmppClientToServerConnectionInternal.class);
+
+        XmppWebsocketTransportModule transportModule
+                        = new XmppWebsocketTransportModule(websocketTransportModuleDescriptor, connectionInternal);
+
+        XmppWebsocketTransportModule.XmppWebsocketTransport transport = transportModule.getTransport();
+
+        assertThrows(AssertionError.class, () -> transport.new DiscoveredWebsocketEndpoints(null));
+        assertThrows(AssertionError.class, () -> transport.new WebsocketEndpointsDiscoveryFailed(null));
+
+        WebsocketRemoteConnectionEndpoint endpoint = new WebsocketRemoteConnectionEndpoint("wss://localhost.org:7443/ws/");
+
+        List<WebsocketRemoteConnectionEndpoint> discoveredRemoteConnectionEndpoints = new ArrayList<>();
+        discoveredRemoteConnectionEndpoints.add(endpoint);
+
+        HttpLookupFailure httpLookupFailure = new RemoteConnectionEndpointLookupFailure.HttpLookupFailure(null, null);
+        List<RemoteConnectionEndpointLookupFailure> failureList = new ArrayList<>();
+        failureList.add(httpLookupFailure);
+        Result result = new Result(discoveredRemoteConnectionEndpoints, failureList);
+
+        DiscoveredWebsocketEndpoints discoveredWebsocketEndpoints = transport.new DiscoveredWebsocketEndpoints(result);
+        assertNotNull(discoveredWebsocketEndpoints.getResult());
+
+        WebsocketEndpointsDiscoveryFailed endpointsDiscoveryFailed = transport.new WebsocketEndpointsDiscoveryFailed(result);
+        assertNotNull(endpointsDiscoveryFailed.toString());
+    }
+
+    @Test
+    public void websocketConnectedResultTest() throws URISyntaxException {
+        WebsocketRemoteConnectionEndpoint connectedEndpoint = new WebsocketRemoteConnectionEndpoint("wss://localhost.org:7443/ws/");
+        assertNotNull(new XmppWebsocketTransportModule.WebsocketConnectedResult(connectedEndpoint));
+    }
+
+    @Test
+    public void lookupConnectionEndpointsTest() throws URISyntaxException {
+        XmppWebsocketTransportModuleDescriptor websocketTransportModuleDescriptor = getWebsocketDescriptor();
+        ModularXmppClientToServerConnectionInternal connectionInternal = mock(ModularXmppClientToServerConnectionInternal.class);
+
+        XmppWebsocketTransportModule transportModule
+                        = new XmppWebsocketTransportModule(websocketTransportModuleDescriptor, connectionInternal);
+
+        XmppWebsocketTransportModule.XmppWebsocketTransport transport = transportModule.getTransport();
+        assertNotNull(transport.lookupConnectionEndpoints());
+
+    }
+
+    private static XmppWebsocketTransportModuleDescriptor getWebsocketDescriptor() throws URISyntaxException {
+        ModularXmppClientToServerConnectionConfiguration.Builder builder = ModularXmppClientToServerConnectionConfiguration
+                .builder();
+
+        XmppWebsocketTransportModuleDescriptor.Builder websocketBuilder = XmppWebsocketTransportModuleDescriptor.getBuilder(builder);
+        websocketBuilder.explicitlySetWebsocketEndpointAndDiscovery(new URI("wss://localhost.org:7443/ws/"), false);
+        return (XmppWebsocketTransportModuleDescriptor) websocketBuilder.build();
+    }
+}

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/elements/WebsocketElementTest.java

@@ -0,0 +1,43 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.elements;
+
+import static org.jivesoftware.smack.test.util.XmlAssertUtil.assertXmlNotSimilar;
+import static org.jivesoftware.smack.test.util.XmlAssertUtil.assertXmlSimilar;
+
+import org.junit.jupiter.api.Test;
+import org.jxmpp.jid.impl.JidCreate;
+import org.jxmpp.stringprep.XmppStringprepException;
+
+public class WebsocketElementTest {
+    private static final String OPEN_ELEMENT = "<open xmlns='urn:ietf:params:xml:ns:xmpp-framing' to='foodomain.foo' version='1.0'/>";
+    private static final String CLOSE_ELEMENT = "<close xmlns='urn:ietf:params:xml:ns:xmpp-framing'/>";
+
+    @Test
+    public void websocketOpenElementTest() throws XmppStringprepException {
+        String openElementXml =  new WebsocketOpenElement(JidCreate.domainBareFrom("foodomain.foo")).toXML().toString();
+        assertXmlSimilar(OPEN_ELEMENT, openElementXml);
+        assertXmlNotSimilar(CLOSE_ELEMENT, new WebsocketOpenElement(JidCreate.domainBareFrom("foodomain.foo")).toXML());
+    }
+
+    @Test
+    public void websocketCloseElementTest() throws XmppStringprepException {
+        String closeElementXml = new WebsocketCloseElement().toXML().toString();
+        assertXmlSimilar(CLOSE_ELEMENT, closeElementXml);
+        assertXmlNotSimilar(OPEN_ELEMENT, closeElementXml);
+    }
+}

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/implementations/AbstractWebsocketTest.java

@@ -0,0 +1,47 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar.
+ *
+ * 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.websocket.implementations;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+public final class AbstractWebsocketTest {
+    private static final String OPEN_ELEMENT = "<open from='localhost.org' id='aov9ihhmmn' xmlns='urn:ietf:params:xml:ns:xmpp-framing' xml:lang='en' version='1.0'/>";
+    private static final String OPEN_STREAM = "<stream from='localhost.org' id='aov9ihhmmn' xmlns='jabber:client' xml:lang='en' version='1.0'>";
+    private static final String CLOSE_ELEMENT = "<close xmlns='urn:ietf:params:xml:ns:xmpp-framing'/>";
+
+    @Test
+    public void getStreamFromOpenElementTest() {
+        String generatedOpenStream = AbstractWebsocket.getStreamFromOpenElement(OPEN_ELEMENT);
+        assertEquals(generatedOpenStream, OPEN_STREAM);
+    }
+
+    @Test
+    public void isOpenElementTest() {
+        assertTrue(AbstractWebsocket.isOpenElement(OPEN_ELEMENT));
+        assertFalse(AbstractWebsocket.isOpenElement(OPEN_STREAM));
+    }
+
+    @Test
+    public void isCloseElementTest() {
+        assertTrue(AbstractWebsocket.isCloseElement(CLOSE_ELEMENT));
+        assertFalse(AbstractWebsocket.isCloseElement(OPEN_STREAM));
+    }
+}

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/implementations/ProviderTest.java

@@ -0,0 +1,61 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar.
+ *
+ * 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.websocket.implementations;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.lang.reflect.InvocationTargetException;
+import java.net.URISyntaxException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jivesoftware.smack.c2s.internal.ModularXmppClientToServerConnectionInternal;
+import org.jivesoftware.smack.websocket.XmppWebsocketTransportModule.XmppWebsocketTransport.DiscoveredWebsocketEndpoints;
+
+import org.jivesoftware.smack.websocket.implementations.okhttp.OkHttpWebsocket;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpoint;
+import org.jivesoftware.smack.websocket.rce.WebsocketRemoteConnectionEndpointLookup.Result;
+
+import org.junit.jupiter.api.Test;
+
+public class ProviderTest {
+    @Test
+    public void providerTest() {
+        assertThrows(IllegalArgumentException.class, () -> WebsocketImplProvider.getWebsocketImpl(OkHttpWebsocket.class, null, null));
+    }
+
+    @Test
+    public void getImplTest() throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, URISyntaxException {
+        WebsocketRemoteConnectionEndpoint endpoint = new WebsocketRemoteConnectionEndpoint("wss://localhost.org:7443/ws/");
+
+        List<WebsocketRemoteConnectionEndpoint> discoveredRemoteConnectionEndpoints = new ArrayList<>();
+        discoveredRemoteConnectionEndpoints.add(endpoint);
+
+        Result result = new Result(discoveredRemoteConnectionEndpoints, null);
+
+        DiscoveredWebsocketEndpoints discoveredWebsocketEndpoints = mock(DiscoveredWebsocketEndpoints.class);
+        when(discoveredWebsocketEndpoints.getResult()).thenReturn(result);
+
+        ModularXmppClientToServerConnectionInternal connectionInternal = mock(ModularXmppClientToServerConnectionInternal.class);
+
+        assertNotNull(WebsocketImplProvider.getWebsocketImpl(OkHttpWebsocket.class, connectionInternal, discoveredWebsocketEndpoints));
+    }
+}

smack-websocket/src/test/java/org/jivesoftware/smack/websocket/rce/WebsocketRemoteConnectionEndpointTest.java

@@ -0,0 +1,45 @@
+/**
+ *
+ * Copyright 2020 Aditya Borikar
+ *
+ * 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.websocket.rce;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.net.URISyntaxException;
+
+import org.jivesoftware.smack.datatypes.UInt16;
+
+import org.junit.jupiter.api.Test;
+
+public class WebsocketRemoteConnectionEndpointTest {
+    @Test
+    public void endpointTest() throws URISyntaxException {
+        String endpointString = "ws://fooDomain.org:7070/ws/";
+        WebsocketRemoteConnectionEndpoint endpoint = new WebsocketRemoteConnectionEndpoint(endpointString);
+        assertEquals("fooDomain.org", endpoint.getHost());
+        assertEquals(UInt16.from(7070), endpoint.getPort());
+        assertEquals(endpointString, endpoint.getWebsocketEndpoint().toString());
+    }
+
+    @Test
+    public void faultyEndpointTest() {
+        String faultyProtocolString = "wst://fooDomain.org:7070/ws/";
+        assertThrows(IllegalArgumentException.class, () -> {
+            new WebsocketRemoteConnectionEndpoint(faultyProtocolString);
+        });
+    }
+}

smack-websocket/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker

@@ -0,0 +1 @@
+mock-maker-inline

version

@@ -1 +1 @@
-4.4.0-alpha6-SNAPSHOT
+4.5.0-alpha1-SNAPSHOT