Introduce Smack's Modular Connection Architecture

This is a complete redesign of what was previously
XmppNioTcpConnection. The new architecture allows to extend an XMPP
client to server (c2s) connection with new transport bindings and
other extensions.

smack-java8-full/build.gradle

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+description = """\
+Full Smack library for Java SE."""
+
+dependencies {
+	api project(':smack-bosh')
+	api project(':smack-debug')
+	api project(':smack-experimental')
+	api project(':smack-extensions')
+	api project(':smack-java7')
+	api project(':smack-legacy')
+	api project(':smack-omemo')
+	api project(':smack-omemo-signal')
+	api project(':smack-openpgp')
+	api project(':smack-resolver-minidns')
+	api project(':smack-resolver-minidns-dox')
+	api project(':smack-tcp')
+
+	testImplementation project(path: ":smack-core", configuration: "testRuntime")
+}
+
+task printModularXmppClientToServerConnectionStateGraph(type: JavaExec) {
+	classpath sourceSets.main.runtimeClasspath
+	main 'org.jivesoftware.smack.full.ModularXmppClientToServerConnectionTool'
+}
+
+task generateModularXmppClientToServerConnectionStateGraph(type: JavaExec) {
+	// TODO: Filter out all files which do not contain the String
+	// StateDescriptor.
+	inputs.files file('..').listFiles().findAll {it.name.endsWith('.java')}
+	outputs.files 'src/javadoc/org/jivesoftware/smack/full/doc-files/ModularXmppClientToServerConnectionStateGraph.dot'
+	classpath sourceSets.main.runtimeClasspath
+	main 'org.jivesoftware.smack.full.ModularXmppClientToServerConnectionTool'
+	args outputs.files
+}
+
+task convertModularXmppClientToServerConnectionStateGraphDotToPng(type: Exec) {
+	dependsOn generateModularXmppClientToServerConnectionStateGraph
+	inputs.files 'src/javadoc/org/jivesoftware/smack/full/doc-files/ModularXmppClientToServerConnectionStateGraph.dot'
+	outputs.files 'src/javadoc/org/jivesoftware/smack/full/doc-files/ModularXmppClientToServerConnectionStateGraph.png'
+
+	executable 'dot'
+	args "-Tpng", "-o", "${outputs.files.first()}",  "${inputs.files.first()}"
+}
+
+task cleanGenerateFiles(type: Delete) {
+	delete 'src/javadoc/org/jivesoftware/smack/full/doc-files/ModularXmppClientToServerConnectionStateGraph.dot', 'src/javadoc/org/jivesoftware/smack/full/doc-files/ModularXmppClientToServerConnectionStateGraph.png'
+}
+clean.dependsOn cleanGenerateFiles

smack-java8-full/src/javadoc/org/jivesoftware/smack/full/doc-files/.gitignore

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+/ModularXmppClientToServerConnectionStateGraph.dot
+/ModularXmppClientToServerConnectionStateGraph.png

smack-java8-full/src/main/java/org/jivesoftware/smack/full/ModularXmppClientToServerConnectionTool.java

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+/**
+ *
+ * Copyright 2018-2020 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.
+ */
+package org.jivesoftware.smack.full;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.PrintWriter;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.jivesoftware.smack.c2s.ModularXmppClientToServerConnectionConfiguration;
+
+import org.jxmpp.stringprep.XmppStringprepException;
+
+public class ModularXmppClientToServerConnectionTool {
+
+    @SuppressWarnings("DefaultCharset")
+    public static void main(String[] args) throws XmppStringprepException, FileNotFoundException {
+
+        final PrintWriter pw;
+        final boolean breakStateName;
+
+        switch (args.length) {
+        case 0:
+            pw = new PrintWriter(System.out);
+            breakStateName = false;
+            break;
+        case 1:
+            Path outputFilePath = Paths.get(args[0]);
+            File outputFile = outputFilePath.toFile();
+            if (outputFile.exists()) {
+                outputFile.delete();
+            }
+            pw = new PrintWriter(outputFile);
+            breakStateName = true;
+            break;
+        default:
+            throw new IllegalArgumentException("At most one argument allowed");
+        }
+
+        printStateGraph(pw, breakStateName);
+        pw.flush();
+    }
+
+    public static void printStateGraph(PrintWriter pw, boolean breakStateName) throws XmppStringprepException {
+        ModularXmppClientToServerConnectionConfiguration.Builder configurationBuilder = ModularXmppClientToServerConnectionConfiguration.builder()
+                        .setUsernameAndPassword("user", "password")
+                        .setXmppDomain("example.org");
+
+        ModularXmppClientToServerConnectionConfiguration configuration = configurationBuilder.build();
+
+        configuration.printStateGraphInDotFormat(pw, breakStateName);
+
+        pw.flush();
+    }
+
+}

smack-java8-full/src/main/java/org/jivesoftware/smack/full/package-info.java

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+/**
+ *
+ * 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.
+ */
+
+/**
+ * The Smack XMPP client library.
+
+ * <h2>Modular XMPP c2s connection</h2>
+ * <p>
+ * The graph below shows the current states of the modular xmpp client connection. Only some states are final states,
+ * most states are intermediate states in order to reach a final state.
+ * </p>
+ * <img src="doc-files/ModularXmppClientToServerConnectionStateGraph.png" alt="The state graph of XmppNioTcpConnection">
+ */
+package org.jivesoftware.smack.full;

smack-java8-full/src/test/java/org/jivesoftware/smack/full/ModularXmppClientToServerConnectionStateGraphTest.java

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+/**
+ *
+ * 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.
+ */
+package org.jivesoftware.smack.full;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+
+import org.jivesoftware.smack.util.EqualsUtil;
+import org.jivesoftware.smack.util.HashCode;
+
+import com.google.common.io.Resources;
+import org.jgrapht.graph.DefaultEdge;
+import org.jgrapht.graph.DirectedPseudograph;
+import org.jgrapht.io.DOTImporter;
+import org.jgrapht.io.ImportException;
+import org.junit.jupiter.api.Test;
+
+public class ModularXmppClientToServerConnectionStateGraphTest {
+
+    @Test
+    public void testStateGraphDotOutput() throws IOException, ImportException {
+        URL stateGraphDotFileUrl = Resources.getResource("state-graph.dot");
+        String expectedStateGraphDot = Resources.toString(stateGraphDotFileUrl, StandardCharsets.UTF_8);
+
+        StringWriter sw = new StringWriter();
+        PrintWriter pw  = new PrintWriter(sw);
+        ModularXmppClientToServerConnectionTool.printStateGraph(pw, false);
+        String currentStateGraphDot = sw.toString();
+
+        @SuppressWarnings("serial")
+        DOTImporter<String, DefaultEdge> dotImporter = new DOTImporter<>(
+                (id, attributes) -> id,
+                (from, to, label, attributes) -> {
+                        return new DefaultEdge() {
+                            @Override
+                            public int hashCode() {
+                                return HashCode.builder()
+                                        .append(getSource())
+                                        .append(getTarget())
+                                        .build();
+                            }
+
+                            @Override
+                            public boolean equals(Object other) {
+                                return EqualsUtil.equals(this, other, (b, o) ->
+                                    b.append(getSource(), o.getSource())
+                                     .append(getTarget(), o.getTarget())
+                                );
+                            }
+                        };
+                    }
+                );
+
+        DirectedPseudograph<String, DefaultEdge> currentStateGraph = new DirectedPseudograph<>(DefaultEdge.class);
+        DirectedPseudograph<String, DefaultEdge> expectedStateGraph = new DirectedPseudograph<>(DefaultEdge.class);
+
+        dotImporter.importGraph(expectedStateGraph, new StringReader(expectedStateGraphDot));
+        dotImporter.importGraph(currentStateGraph, new StringReader(currentStateGraphDot));
+
+        assertEquals(expectedStateGraph, currentStateGraph);
+    }
+
+}

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

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+digraph {
+  "Disconnected" -> "LookupRemoteConnectionEndpoints";
+  "LookupRemoteConnectionEndpoints" -> "EstablishingTcpConnection";
+  "EstablishingTcpConnection" -> "EstablishTls (RFC 6120 § 5)" [xlabel="1"];
+  "EstablishTls (RFC 6120 § 5)" -> "ConnectedButUnauthenticated";
+  "ConnectedButUnauthenticated" -> "Bind2 (XEP-0386)" [xlabel="1"];
+  "Bind2 (XEP-0386)" -> "AuthenticatedAndResourceBound";
+  "AuthenticatedAndResourceBound" -> "Shutdown" [xlabel="1"];
+  "Shutdown" -> "CloseConnection";
+  "CloseConnection" -> "Disconnected";
+  "AuthenticatedAndResourceBound" -> "InstantShutdown" [xlabel="2"];
+  "InstantShutdown" -> "CloseConnection";
+"AuthenticatedAndResourceBound" [ style=filled ]
+"Bind2 (XEP-0386)" [ style=dashed ]
+  "ConnectedButUnauthenticated" -> "InstantStreamResumption (XEP-0397)" [xlabel="2"];
+  "InstantStreamResumption (XEP-0397)" -> "AuthenticatedAndResourceBound";
+"InstantStreamResumption (XEP-0397)" [ style=dashed ]
+  "ConnectedButUnauthenticated" -> "SaslAuthentication (RFC 6120 § 6)" [xlabel="3"];
+  "SaslAuthentication (RFC 6120 § 6)" -> "AuthenticatedButUnbound";
+  "AuthenticatedButUnbound" -> "Compression (XEP-0138)" [xlabel="1"];
+  "Compression (XEP-0138)" -> "AuthenticatedButUnbound";
+  "AuthenticatedButUnbound" -> "ResumeStream (XEP-0198)" [xlabel="2"];
+  "ResumeStream (XEP-0198)" -> "AuthenticatedAndResourceBound";
+"ResumeStream (XEP-0198)" [ style=dashed ]
+  "AuthenticatedButUnbound" -> "ResourceBinding (RFC 6120 § 7)" [xlabel="3"];
+  "ResourceBinding (RFC 6120 § 7)" -> "EnableStreamManagement (XEP-0198)" [xlabel="1"];
+  "EnableStreamManagement (XEP-0198)" -> "AuthenticatedAndResourceBound";
+"EnableStreamManagement (XEP-0198)" [ style=dashed ]
+  "ResourceBinding (RFC 6120 § 7)" -> "AuthenticatedAndResourceBound" [xlabel="2"];
+"AuthenticatedButUnbound" [ style=bold ]
+  "ConnectedButUnauthenticated" -> "Shutdown" [xlabel="4"];
+  "ConnectedButUnauthenticated" -> "InstantShutdown" [xlabel="5"];
+"ConnectedButUnauthenticated" [ style=filled ]
+  "EstablishingTcpConnection" -> "ConnectedButUnauthenticated" [xlabel="2"];
+"Disconnected" [ style=filled ]
+}