Merge branch 'master' into native-crypto

# Conflicts:
#	native/src/main/java/com/velocitypowered/natives/util/Natives.java

.gitignore

@@ -11,6 +11,7 @@
 .idea/**/usage.statistics.xml
 .idea/**/dictionaries
 .idea/**/shelf
+.idea/**/compiler.xml
 
 # Sensitive or high-churn files
 .idea/**/dataSources/
@@ -85,6 +86,15 @@ modules.xml
 # BlueJ files
 *.ctxt
 
+# Eclipse #
+**/.classpath
+**/.project
+**/.settings/
+**/bin/
+
+# NetBeans Gradle#
+.nb-gradle/
+
 # Mobile Tools for Java (J2ME)
 .mtj.tmp/
 
@@ -102,7 +112,7 @@ hs_err_pid*
 
 ### Gradle ###
 .gradle
-/build/
+build/
 
 # Ignore Gradle GUI config
 gradle-app.setting
@@ -121,4 +131,7 @@ gradle-app.setting
 
 # Other trash
 logs/
-velocity.toml
+/velocity.toml
+server-icon.png
+/bin/
+run/

Jenkinsfile

@@ -1,8 +1,8 @@
 pipeline {
   agent {
     docker {
-      image 'openjdk:8-jdk-slim'
-      args '-v gradle-cache:/root/.gradle:rw'
+      image 'velocitypowered/openjdk8-plus-git:slim'
+      args '-v gradle-cache:/root/.gradle:rw -v maven-repo:/maven-repo:rw -v javadoc:/javadoc'
     }
 
   }
@@ -18,5 +18,15 @@ pipeline {
         sh './gradlew test'
       }
     }
+    stage('Deploy Artifacts') {
+      steps {
+        sh 'export MAVEN_DEPLOYMENT=true; ./gradlew publish'
+      }
+    }
+    stage('Deploy Javadoc') {
+      steps {
+        sh 'rsync -av --delete ./api/build/docs/javadoc/ /javadoc'
+      }
+    }
   }
 }

README.md

@@ -1,6 +1,7 @@
 # Velocity
 
 [![Build Status](https://img.shields.io/jenkins/s/https/ci.velocitypowered.com/job/velocity/job/master.svg)](https://ci.velocitypowered.com/job/velocity/job/master/)
+[![Join our Discord](https://img.shields.io/discord/472484458856185878.svg?logo=discord&label=)](https://discord.gg/8cB9Bgf)
 
 Velocity is a next-generation Minecraft: Java Edition proxy suite. It is
 designed specifically with mass-scale Minecraft in mind.
@@ -22,10 +23,17 @@ wrapper script (`./gradlew`) as our CI builds using it.
 
 It is sufficient to run `./gradlew build` to run the full build cycle.
 
+## Running
+
+Once you've built Velocity, you can copy and run the `-all` JAR from
+`proxy/build/libs`. Velocity will generate a default configuration file
+and you can configure it from there.
+
+Alternatively, you can get the proxy JAR from the [downloads](https://www.velocitypowered.com/downloads)
+page.
+
 ## Status
 
-Velocity is far from finished, but most of the essential pieces are in place:
-you can switch between two servers running Minecraft 1.9-1.13. More versions
-and functionality is planned.
-
-You should join us on **irc.spi.gt** `#velocity` or send us a pull request.
+Velocity is far from finished, but most of the essential pieces you would
+expect are in place. Velocity supports Minecraft 1.8-1.13. More functionality
+is planned.

api/build.gradle

@@ -1,13 +1,24 @@
 plugins {
     id 'java'
     id 'com.github.johnrengelman.shadow' version '2.0.4'
+    id 'maven-publish'
+}
+
+sourceSets {
+    ap {
+        compileClasspath += main.compileClasspath + main.output
+    }
 }
 
 dependencies {
     compile 'com.google.code.gson:gson:2.8.5'
     compile "com.google.guava:guava:${guavaVersion}"
-    compile 'net.kyori:text:1.12-1.6.0-SNAPSHOT'
+    compile 'net.kyori:text:1.12-1.6.4'
     compile 'com.moandjiezana.toml:toml4j:0.7.2'
+    compile "org.slf4j:slf4j-api:${slf4jVersion}"
+    compile 'com.google.inject:guice:4.2.0'
+    compile 'org.checkerframework:checker-qual:2.5.4'
+
     testCompile "org.junit.jupiter:junit-jupiter-api:${junitVersion}"
     testCompile "org.junit.jupiter:junit-jupiter-engine:${junitVersion}"
 }
@@ -20,6 +31,15 @@ task javadocJar(type: Jar) {
 task sourcesJar(type: Jar) {
     classifier 'sources'
     from sourceSets.main.allSource
+    from sourceSets.ap.output
+}
+
+jar {
+    from sourceSets.ap.output
+}
+
+shadowJar {
+    from sourceSets.ap.output
 }
 
 artifacts {
@@ -27,3 +47,39 @@ artifacts {
     archives shadowJar
     archives sourcesJar
 }
+
+javadoc {
+    options.encoding = 'UTF-8'
+    options.charSet = 'UTF-8'
+    options.links(
+            'http://www.slf4j.org/apidocs/',
+            'https://google.github.io/guava/releases/25.1-jre/api/docs/',
+            'https://google.github.io/guice/api-docs/4.2/javadoc/',
+            'https://jd.kyori.net/text/1.12-1.6.4/',
+            'https://docs.oracle.com/javase/8/docs/api/'
+    )
+
+    // Disable the crazy super-strict doclint tool in Java 8
+    options.addStringOption('Xdoclint:none', '-quiet')
+}
+
+publishing {
+    publications {
+        mavenJava(MavenPublication) {
+            from components.java
+
+            artifact sourcesJar
+            artifact javadocJar
+        }
+    }
+
+    repositories {
+        maven {
+            name = 'myRepo'
+            def base = project.ext.getCurrentBranchName() == "master" ? 'file:///maven-repo' : File.createTempDir().toURI().toURL().toString()
+            def releasesRepoUrl = "$base/releases"
+            def snapshotsRepoUrl = "$base/snapshots"
+            url = version.endsWith('SNAPSHOT') ? snapshotsRepoUrl : releasesRepoUrl
+        }
+    }
+}

api/src/ap/java/com/velocitypowered/api/plugin/ap/PluginAnnotationProcessor.java

@@ -0,0 +1,87 @@
+package com.velocitypowered.api.plugin.ap;
+
+import com.google.gson.Gson;
+import com.velocitypowered.api.plugin.Plugin;
+import com.velocitypowered.api.plugin.PluginDescription;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.ProcessingEnvironment;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.ElementKind;
+import javax.lang.model.element.Name;
+import javax.lang.model.element.TypeElement;
+import javax.tools.Diagnostic;
+import javax.tools.FileObject;
+import javax.tools.StandardLocation;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.Writer;
+import java.util.*;
+
+@SupportedAnnotationTypes({"com.velocitypowered.api.plugin.Plugin"})
+public class PluginAnnotationProcessor extends AbstractProcessor {
+    private ProcessingEnvironment environment;
+    private String pluginClassFound;
+    private boolean warnedAboutMultiplePlugins;
+
+    @Override
+    public synchronized void init(ProcessingEnvironment processingEnv) {
+        this.environment = processingEnv;
+    }
+
+    @Override
+    public SourceVersion getSupportedSourceVersion() {
+        return SourceVersion.latestSupported();
+    }
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+        if (roundEnv.processingOver()) {
+            return false;
+        }
+
+        for (Element element : roundEnv.getElementsAnnotatedWith(Plugin.class)) {
+            if (element.getKind() != ElementKind.CLASS) {
+                environment.getMessager().printMessage(Diagnostic.Kind.ERROR, "Only classes can be annotated with "
+                        + Plugin.class.getCanonicalName());
+                return false;
+            }
+
+            Name qualifiedName = ((TypeElement) element).getQualifiedName();
+
+            if (Objects.equals(pluginClassFound, qualifiedName.toString())) {
+                if (!warnedAboutMultiplePlugins) {
+                    environment.getMessager().printMessage(Diagnostic.Kind.WARNING, "Velocity does not yet currently support " +
+                            "multiple plugins. We are using " + pluginClassFound + " for your plugin's main class.");
+                    warnedAboutMultiplePlugins = true;
+                }
+                return false;
+            }
+
+            Plugin plugin = element.getAnnotation(Plugin.class);
+            if (!PluginDescription.ID_PATTERN.matcher(plugin.id()).matches()) {
+                environment.getMessager().printMessage(Diagnostic.Kind.ERROR, "Invalid ID for plugin "
+                        + qualifiedName + ". IDs must start alphabetically, have alphanumeric characters, and can " +
+                        "contain dashes or underscores.");
+                return false;
+            }
+
+            // All good, generate the velocity-plugin.json.
+            SerializedPluginDescription description = SerializedPluginDescription.from(plugin, qualifiedName.toString());
+            try {
+                FileObject object = environment.getFiler().createResource(StandardLocation.CLASS_OUTPUT, "", "velocity-plugin.json");
+                try (Writer writer = new BufferedWriter(object.openWriter())) {
+                    new Gson().toJson(description, writer);
+                }
+                pluginClassFound = qualifiedName.toString();
+            } catch (IOException e) {
+                environment.getMessager().printMessage(Diagnostic.Kind.ERROR, "Unable to generate plugin file");
+            }
+        }
+
+        return false;
+    }
+}

api/src/ap/java/com/velocitypowered/api/plugin/ap/SerializedPluginDescription.java

@@ -0,0 +1,151 @@
+package com.velocitypowered.api.plugin.ap;
+
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+import com.velocitypowered.api.plugin.Plugin;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+public class SerializedPluginDescription {
+    // @Nullable is used here to make GSON skip these in the serialized file
+    private final String id;
+    private final @Nullable String name;
+    private final @Nullable String version;
+    private final @Nullable String description;
+    private final @Nullable String url;
+    private final @Nullable List<String> authors;
+    private final @Nullable List<Dependency> dependencies;
+    private final String main;
+
+    public SerializedPluginDescription(String id, String name, String version, String description, String url,
+            List<String> authors, List<Dependency> dependencies, String main) {
+        this.id = Preconditions.checkNotNull(id, "id");
+        this.name = Strings.emptyToNull(name);
+        this.version = Strings.emptyToNull(version);
+        this.description = Strings.emptyToNull(description);
+        this.url = Strings.emptyToNull(url);
+        this.authors = authors == null || authors.isEmpty() ? null : authors;
+        this.dependencies = dependencies == null || dependencies.isEmpty() ? null : dependencies;
+        this.main = Preconditions.checkNotNull(main, "main");
+    }
+
+    public static SerializedPluginDescription from(Plugin plugin, String qualifiedName) {
+        List<Dependency> dependencies = new ArrayList<>();
+        for (com.velocitypowered.api.plugin.Dependency dependency : plugin.dependencies()) {
+            dependencies.add(new Dependency(dependency.id(), dependency.optional()));
+        }
+        return new SerializedPluginDescription(plugin.id(), plugin.name(), plugin.version(), plugin.description(), plugin.url(),
+                Arrays.stream(plugin.authors()).filter(author -> !author.isEmpty()).collect(Collectors.toList()), dependencies, qualifiedName);
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public @Nullable String getName() {
+        return name;
+    }
+
+    public @Nullable String getVersion() {
+        return version;
+    }
+
+    public @Nullable String getDescription() {
+        return description;
+    }
+
+    public @Nullable String getUrl() {
+        return url;
+    }
+
+    public @Nullable List<String> getAuthors() {
+        return authors;
+    }
+
+    public @Nullable List<Dependency> getDependencies() {
+        return dependencies;
+    }
+
+    public String getMain() {
+        return main;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        SerializedPluginDescription that = (SerializedPluginDescription) o;
+        return Objects.equals(id, that.id) &&
+                Objects.equals(name, that.name) &&
+                Objects.equals(version, that.version) &&
+                Objects.equals(description, that.description) &&
+                Objects.equals(url, that.url) &&
+                Objects.equals(authors, that.authors) &&
+                Objects.equals(dependencies, that.dependencies) &&
+                Objects.equals(main, that.main);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, name, version, description, url, authors, dependencies);
+    }
+
+    @Override
+    public String toString() {
+        return "SerializedPluginDescription{" +
+                "id='" + id + '\'' +
+                ", name='" + name + '\'' +
+                ", version='" + version + '\'' +
+                ", description='" + description + '\'' +
+                ", url='" + url + '\'' +
+                ", authors=" + authors +
+                ", dependencies=" + dependencies +
+                ", main='" + main + '\'' +
+                '}';
+    }
+
+    public static class Dependency {
+        private final String id;
+        private final boolean optional;
+
+        public Dependency(String id, boolean optional) {
+            this.id = id;
+            this.optional = optional;
+        }
+
+        public String getId() {
+            return id;
+        }
+
+        public boolean isOptional() {
+            return optional;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Dependency that = (Dependency) o;
+            return optional == that.optional &&
+                    Objects.equals(id, that.id);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(id, optional);
+        }
+
+        @Override
+        public String toString() {
+            return "Dependency{" +
+                    "id='" + id + '\'' +
+                    ", optional=" + optional +
+                    '}';
+        }
+    }
+}

api/src/ap/resources/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1 @@
+com.velocitypowered.api.plugin.ap.PluginAnnotationProcessor

api/src/main/java/com/velocitypowered/api/command/Command.java

@@ -0,0 +1,29 @@
+package com.velocitypowered.api.command;
+
+import com.google.common.collect.ImmutableList;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.util.List;
+
+/**
+ * Represents a command that can be executed by a {@link CommandSource}, such as a {@link com.velocitypowered.api.proxy.Player}
+ * or the console.
+ */
+public interface Command {
+    /**
+     * Executes the command for the specified {@link CommandSource}.
+     * @param source the source of this command
+     * @param args the arguments for this command
+     */
+    void execute(@NonNull CommandSource source, @NonNull String[] args);
+
+    /**
+     * Provides tab complete suggestions for a command for a specified {@link CommandSource}.
+     * @param source the source to run the command for
+     * @param currentArgs the current, partial arguments for this command
+     * @return tab complete suggestions
+     */
+    default List<String> suggest(@NonNull CommandSource source, @NonNull String[] currentArgs) {
+        return ImmutableList.of();
+    }
+}

api/src/main/java/com/velocitypowered/api/command/CommandManager.java

@@ -0,0 +1,29 @@
+package com.velocitypowered.api.command;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Represents an interface to register a command executor with the proxy.
+ */
+public interface CommandManager {
+    /**
+     * Registers the specified command with the manager with the specified aliases.
+     * @param command the command to register
+     * @param aliases the alias to use
+     */
+    void register(@NonNull Command command, String... aliases);
+
+    /**
+     * Unregisters a command.
+     * @param alias the command alias to unregister
+     */
+    void unregister(@NonNull String alias);
+
+    /**
+     * Attempts to execute a command from the specified {@code cmdLine}.
+     * @param source the command's source
+     * @param cmdLine the command to run
+     * @return true if the command was found and executed, false if it was not
+     */
+    boolean execute(@NonNull CommandSource source, @NonNull String cmdLine);
+}

api/src/main/java/com/velocitypowered/api/command/CommandSource.java

@@ -0,0 +1,16 @@
+package com.velocitypowered.api.command;
+
+import com.velocitypowered.api.permission.PermissionSubject;
+import net.kyori.text.Component;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Represents something that can be used to run a {@link Command}.
+ */
+public interface CommandSource extends PermissionSubject {
+    /**
+     * Sends the specified {@code component} to the invoker.
+     * @param component the text component to send
+     */
+    void sendMessage(@NonNull Component component);
+}

api/src/main/java/com/velocitypowered/api/command/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides a simple command framework.
+ */
+package com.velocitypowered.api.command;

api/src/main/java/com/velocitypowered/api/event/EventHandler.java

@@ -0,0 +1,12 @@
+package com.velocitypowered.api.event;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Represents an interface to perform direct dispatch of an event. This makes integration easier to achieve with platforms
+ * such as RxJava.
+ */
+@FunctionalInterface
+public interface EventHandler<E> {
+    void execute(@NonNull E event);
+}

api/src/main/java/com/velocitypowered/api/event/EventManager.java

@@ -0,0 +1,75 @@
+package com.velocitypowered.api.event;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Allows plugins to register and deregister listeners for event handlers.
+ */
+public interface EventManager {
+    /**
+     * Requests that the specified {@code listener} listen for events and associate it with the {@code plugin}.
+     * @param plugin the plugin to associate with the listener
+     * @param listener the listener to register
+     */
+    void register(@NonNull Object plugin, @NonNull Object listener);
+
+    /**
+     * Requests that the specified {@code handler} listen for events and associate it with the {@code plugin}.
+     * @param plugin the plugin to associate with the handler
+     * @param eventClass the class for the event handler to register
+     * @param handler the handler to register
+     * @param <E> the event type to handle
+     */
+    default <E> void register(@NonNull Object plugin, @NonNull Class<E> eventClass, @NonNull EventHandler<E> handler) {
+        register(plugin, eventClass, PostOrder.NORMAL, handler);
+    }
+
+    /**
+     * Requests that the specified {@code handler} listen for events and associate it with the {@code plugin}.
+     * @param plugin the plugin to associate with the handler
+     * @param eventClass the class for the event handler to register
+     * @param postOrder the order in which events should be posted to the handler
+     * @param handler the handler to register
+     * @param <E> the event type to handle
+     */
+    <E> void register(@NonNull Object plugin, @NonNull Class<E> eventClass, @NonNull PostOrder postOrder, @NonNull EventHandler<E> handler);
+
+    /**
+     * Fires the specified event to the event bus asynchronously. This allows Velocity to continue servicing connections
+     * while a plugin handles a potentially long-running operation such as a database query.
+     * @param event the event to fire
+     * @return a {@link CompletableFuture} representing the posted event
+     */
+    @NonNull <E> CompletableFuture<E> fire(@NonNull E event);
+
+    /**
+     * Posts the specified event to the event bus and discards the result.
+     * @param event the event to fire
+     */
+    default void fireAndForget(@NonNull Object event) {
+        fire(event);
+    }
+
+    /**
+     * Unregisters all listeners for the specified {@code plugin}.
+     * @param plugin the plugin to deregister listeners for
+     */
+    void unregisterListeners(@NonNull Object plugin);
+
+    /**
+     * Unregisters a specific listener for a specific plugin.
+     * @param plugin the plugin associated with the listener
+     * @param listener the listener to deregister
+     */
+    void unregisterListener(@NonNull Object plugin, @NonNull Object listener);
+
+    /**
+     * Unregisters a specific event handler for a specific plugin.
+     * @param plugin the plugin to associate with the handler
+     * @param handler the handler to register
+     * @param <E> the event type to handle
+     */
+    <E> void unregister(@NonNull Object plugin, @NonNull EventHandler<E> handler);
+}

api/src/main/java/com/velocitypowered/api/event/PostOrder.java

@@ -0,0 +1,11 @@
+package com.velocitypowered.api.event;
+
+/**
+ * Represents the order an event will be posted to a listener method, relative
+ * to other listeners.
+ */
+public enum PostOrder {
+
+    FIRST, EARLY, NORMAL, LATE, LAST;
+
+}

api/src/main/java/com/velocitypowered/api/event/ResultedEvent.java

@@ -0,0 +1,114 @@
+package com.velocitypowered.api.event;
+
+import com.google.common.base.Preconditions;
+import net.kyori.text.Component;
+import net.kyori.text.serializer.ComponentSerializers;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import java.util.Optional;
+
+/**
+ * Indicates an event that has a result attached to it.
+ */
+public interface ResultedEvent<R extends ResultedEvent.Result> {
+    /**
+     * Returns the result associated with this event.
+     * @return the result of this event
+     */
+    R getResult();
+
+    /**
+     * Sets the result of this event. The result must be non-null.
+     * @param result the new result
+     */
+    void setResult(@NonNull R result);
+
+    /**
+     * Represents a result for an event.
+     */
+    interface Result {
+        /**
+         * Returns whether or not the event is allowed to proceed. Plugins may choose to skip denied events, and the
+         * proxy will respect the result of this method.
+         * @return whether or not the event is allowed to proceed
+         */
+        boolean isAllowed();
+    }
+
+    /**
+     * A generic "allowed/denied" result.
+     */
+    class GenericResult implements Result {
+        private static final GenericResult ALLOWED = new GenericResult(true);
+        private static final GenericResult DENIED = new GenericResult(true);
+
+        private final boolean allowed;
+
+        private GenericResult(boolean b) {
+            this.allowed = b;
+        }
+
+        @Override
+        public boolean isAllowed() {
+            return allowed;
+        }
+
+        @Override
+        public String toString() {
+            return allowed ? "allowed" : "denied";
+        }
+
+        public static GenericResult allowed() {
+            return ALLOWED;
+        }
+
+        public static GenericResult denied() {
+            return DENIED;
+        }
+    }
+
+    /**
+     * Represents an "allowed/denied" result with a reason allowed for denial.
+     */
+    class ComponentResult implements Result {
+        private static final ComponentResult ALLOWED = new ComponentResult(true, null);
+
+        private final boolean allowed;
+        private final @Nullable Component reason;
+
+        protected ComponentResult(boolean allowed, @Nullable Component reason) {
+            this.allowed = allowed;
+            this.reason = reason;
+        }
+
+        @Override
+        public boolean isAllowed() {
+            return allowed;
+        }
+
+        public Optional<Component> getReason() {
+            return Optional.ofNullable(reason);
+        }
+
+        @Override
+        public String toString() {
+            if (allowed) {
+                return "allowed";
+            }
+            if (reason != null) {
+                return "denied: " + ComponentSerializers.PLAIN.serialize(reason);
+            }
+            return "denied";
+        }
+
+        public static ComponentResult allowed() {
+            return ALLOWED;
+        }
+
+        public static ComponentResult denied(@NonNull Component reason) {
+            Preconditions.checkNotNull(reason, "reason");
+            return new ComponentResult(false, reason);
+        }
+    }
+}

api/src/main/java/com/velocitypowered/api/event/Subscribe.java

@@ -0,0 +1,22 @@
+package com.velocitypowered.api.event;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * An annotation that indicates that this method can be used to listen for an event from the proxy.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Subscribe {
+
+    /**
+     * The order events will be posted to this listener.
+     *
+     * @return the order
+     */
+    PostOrder order() default PostOrder.NORMAL;
+
+}

api/src/main/java/com/velocitypowered/api/event/connection/ConnectionHandshakeEvent.java

@@ -0,0 +1,27 @@
+package com.velocitypowered.api.event.connection;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.InboundConnection;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * This event is fired when a handshake is established between a client and Velocity.
+ */
+public class ConnectionHandshakeEvent {
+    private final @NonNull InboundConnection connection;
+
+    public ConnectionHandshakeEvent(@NonNull InboundConnection connection) {
+        this.connection = Preconditions.checkNotNull(connection, "connection");
+    }
+
+    public InboundConnection getConnection() {
+        return connection;
+    }
+
+    @Override
+    public String toString() {
+        return "ConnectionHandshakeEvent{" +
+                "connection=" + connection +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/event/connection/DisconnectEvent.java

@@ -0,0 +1,28 @@
+package com.velocitypowered.api.event.connection;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.Player;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * This event is fired when a player disconnects from the proxy. Operations on the provided player, aside from basic
+ * data retrieval operations, may behave in undefined ways.
+ */
+public class DisconnectEvent {
+    private @NonNull final Player player;
+
+    public DisconnectEvent(@NonNull Player player) {
+        this.player = Preconditions.checkNotNull(player, "player");
+    }
+
+    public Player getPlayer() {
+        return player;
+    }
+
+    @Override
+    public String toString() {
+        return "DisconnectEvent{" +
+                "player=" + player +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/event/connection/LoginEvent.java

@@ -0,0 +1,41 @@
+package com.velocitypowered.api.event.connection;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.event.ResultedEvent;
+import com.velocitypowered.api.proxy.Player;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * This event is fired once the player has been authenticated but before they connect to a server on the proxy.
+ */
+public class LoginEvent implements ResultedEvent<ResultedEvent.ComponentResult> {
+    private final Player player;
+    private ComponentResult result;
+
+    public LoginEvent(@NonNull Player player) {
+        this.player = Preconditions.checkNotNull(player, "player");
+        this.result = ComponentResult.allowed();
+    }
+
+    public Player getPlayer() {
+        return player;
+    }
+
+    @Override
+    public ComponentResult getResult() {
+        return result;
+    }
+
+    @Override
+    public void setResult(@NonNull ComponentResult result) {
+        this.result = Preconditions.checkNotNull(result, "result");
+    }
+
+    @Override
+    public String toString() {
+        return "LoginEvent{" +
+                "player=" + player +
+                ", result=" + result +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/event/connection/PreLoginEvent.java

@@ -0,0 +1,119 @@
+package com.velocitypowered.api.event.connection;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.event.ResultedEvent;
+import com.velocitypowered.api.proxy.InboundConnection;
+
+import net.kyori.text.Component;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/**
+ * This event is fired when a player has initiated a connection with the proxy but before the proxy authenticates the
+ * player with Mojang or before the player's proxy connection is fully established (for offline mode).
+ */
+public class PreLoginEvent implements ResultedEvent<PreLoginEvent.PreLoginComponentResult> {
+    private final InboundConnection connection;
+    private final String username;
+    private PreLoginComponentResult result;
+
+    public PreLoginEvent(InboundConnection connection, String username) {
+        this.connection = Preconditions.checkNotNull(connection, "connection");
+        this.username = Preconditions.checkNotNull(username, "username");
+        this.result = PreLoginComponentResult.allowed();
+    }
+
+    public InboundConnection getConnection() {
+        return connection;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    @Override
+    public PreLoginComponentResult getResult() {
+        return result;
+    }
+
+    @Override
+    public void setResult(@NonNull PreLoginComponentResult result) {
+        this.result = Preconditions.checkNotNull(result, "result");
+    }
+
+    @Override
+    public String toString() {
+        return "PreLoginEvent{" +
+                "connection=" + connection +
+                ", username='" + username + '\'' +
+                ", result=" + result +
+                '}';
+    }
+
+    /**
+     * Represents an "allowed/allowed with online mode/denied" result with a reason allowed for denial.
+     */
+    public static class PreLoginComponentResult extends ResultedEvent.ComponentResult {
+        private static final PreLoginComponentResult ALLOWED = new PreLoginComponentResult((Component) null);
+        private static final PreLoginComponentResult FORCE_ONLINEMODE = new PreLoginComponentResult(true);
+
+        private final boolean onlineMode;
+
+        /**
+         * Allows online mode to be enabled for the player connection, if Velocity is running in offline mode.
+         * @param allowedOnlineMode if true, online mode will be used for the connection
+         */
+        private PreLoginComponentResult(boolean allowedOnlineMode) {
+            super(true, null);
+            this.onlineMode = allowedOnlineMode;
+        }
+
+        private PreLoginComponentResult(@Nullable Component reason) {
+            super(reason == null, reason);
+            // Don't care about this
+            this.onlineMode = false;
+        }
+
+        public boolean isOnlineModeAllowed() {
+            return this.onlineMode;
+        }
+
+        @Override
+        public String toString() {
+            if (isOnlineModeAllowed()) {
+                return "allowed with online mode";
+            }
+            
+            return super.toString();
+        }
+
+        /**
+         * Returns a result indicating the connection will be allowed through the proxy.
+         * @return the allowed result
+         */
+        public static PreLoginComponentResult allowed() {
+            return ALLOWED;
+        }
+
+        /**
+         * Returns a result indicating the connection will be allowed through the proxy, but the connection will be
+         * forced to use online mode provided that the proxy is in offline mode. This acts similarly to {@link #allowed()}
+         * on an online-mode proxy.
+         * @return the result
+         */
+        public static PreLoginComponentResult forceOnlineMode() {
+            return FORCE_ONLINEMODE;
+        }
+
+        /**
+         * Denies the login with the specified reason.
+         * @param reason the reason for disallowing the connection
+         * @return a new result
+         */
+        public static PreLoginComponentResult denied(@NonNull Component reason) {
+            Preconditions.checkNotNull(reason, "reason");
+            return new PreLoginComponentResult(reason);
+        }
+    }
+}

api/src/main/java/com/velocitypowered/api/event/connection/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides events for handling incoming connections to the proxy and loigns.
+ */
+package com.velocitypowered.api.event.connection;

api/src/main/java/com/velocitypowered/api/event/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides core support for handling events with Velocity. Subpackages include event classes.
+ */
+package com.velocitypowered.api.event;

api/src/main/java/com/velocitypowered/api/event/permission/PermissionsSetupEvent.java

@@ -0,0 +1,64 @@
+package com.velocitypowered.api.event.permission;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.permission.PermissionFunction;
+import com.velocitypowered.api.permission.PermissionProvider;
+import com.velocitypowered.api.permission.PermissionSubject;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/**
+ * Called when a {@link PermissionSubject}'s permissions are being setup.
+ *
+ * <p>This event is only called once per subject, on initialisation.</p>
+ */
+public class PermissionsSetupEvent {
+    private final PermissionSubject subject;
+    private final PermissionProvider defaultProvider;
+    private PermissionProvider provider;
+
+    public PermissionsSetupEvent(PermissionSubject subject, PermissionProvider provider) {
+        this.subject = Preconditions.checkNotNull(subject, "subject");
+        this.provider = this.defaultProvider = Preconditions.checkNotNull(provider, "provider");
+    }
+
+    public @NonNull PermissionSubject getSubject() {
+        return this.subject;
+    }
+
+    /**
+     * Uses the provider function to obtain a {@link PermissionFunction} for
+     * the subject.
+     *
+     * @param subject the subject
+     * @return the obtained permission function
+     */
+    public @NonNull PermissionFunction createFunction(PermissionSubject subject) {
+        return this.provider.createFunction(subject);
+    }
+
+    public @NonNull PermissionProvider getProvider() {
+        return this.provider;
+    }
+
+    /**
+     * Sets the {@link PermissionFunction} that should be used for the subject.
+     *
+     * <p>Specifying <code>null</code> will reset the provider to the default
+     * instance given when the event was posted.</p>
+     *
+     * @param provider the provider
+     */
+    public void setProvider(@Nullable PermissionProvider provider) {
+        this.provider = provider == null ? this.defaultProvider : provider;
+    }
+
+    @Override
+    public String toString() {
+        return "PermissionsSetupEvent{" +
+                "subject=" + subject +
+                ", defaultProvider=" + defaultProvider +
+                ", provider=" + provider +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/event/permission/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides events to handle setting up permissions for permission subjects.
+ */
+package com.velocitypowered.api.event.permission;

api/src/main/java/com/velocitypowered/api/event/player/GameProfileRequestEvent.java

@@ -0,0 +1,71 @@
+package com.velocitypowered.api.event.player;
+
+import com.velocitypowered.api.proxy.InboundConnection;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.util.GameProfile;
+
+/**
+ * This event is fired after the {@link com.velocitypowered.api.event.connection.PreLoginEvent} in order to set up the
+ * game profile for the user. This can be used to configure a custom profile for a user, i.e. skin replacement.
+ */
+public class GameProfileRequestEvent {
+    private final String username;
+    private final InboundConnection connection;
+    private final GameProfile originalProfile;
+    private final boolean onlineMode;
+    private GameProfile gameProfile;
+
+    public GameProfileRequestEvent(InboundConnection connection, GameProfile originalProfile, boolean onlineMode) {
+        this.connection = Preconditions.checkNotNull(connection, "connection");
+        this.originalProfile = Preconditions.checkNotNull(originalProfile, "originalProfile");
+        this.username = originalProfile.getName();
+        this.onlineMode = onlineMode;
+    }
+
+    public InboundConnection getConnection() {
+        return connection;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+    
+    public GameProfile getOriginalProfile() {
+        return originalProfile;
+    }
+    
+    public boolean isOnlineMode() {
+        return onlineMode;
+    }
+
+    /**
+     * Returns the game profile that will be used to initialize the connection with. Should no profile be currently
+     * specified, the one generated by the proxy (for offline mode) or retrieved from the Mojang session servers (for
+     * online mode) will be returned instead.
+     * @return the user's {@link GameProfile}
+     */
+    public GameProfile getGameProfile() {
+        return gameProfile == null ? originalProfile : gameProfile;
+    }
+
+    /**
+     * Sets the game profile to use for this connection. It is invalid to use this method on an online-mode connection.
+     * @param gameProfile the profile to use for the connection, {@code null} uses the original profile
+     */
+    public void setGameProfile(@Nullable GameProfile gameProfile) {
+        Preconditions.checkState(!onlineMode, "Connection is in online mode, profiles can not be faked");
+        this.gameProfile = gameProfile;
+    }
+
+    @Override
+    public String toString() {
+        return "GameProfileRequestEvent{"+
+                    "username=" + username +
+                    ", gameProfile=" + gameProfile +
+                    "}";
+    }
+    
+    
+}

api/src/main/java/com/velocitypowered/api/event/player/ServerConnectedEvent.java

@@ -0,0 +1,35 @@
+package com.velocitypowered.api.event.player;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+
+/**
+ * This event is fired once the player has successfully connected to the target server and the connection to the previous
+ * server has been de-established.
+ */
+public class ServerConnectedEvent {
+    private final Player player;
+    private final ServerInfo server;
+
+    public ServerConnectedEvent(Player player, ServerInfo server) {
+        this.player = Preconditions.checkNotNull(player, "player");
+        this.server = Preconditions.checkNotNull(server, "server");
+    }
+
+    public Player getPlayer() {
+        return player;
+    }
+
+    public ServerInfo getServer() {
+        return server;
+    }
+
+    @Override
+    public String toString() {
+        return "ServerConnectedEvent{" +
+                "player=" + player +
+                ", server=" + server +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/event/player/ServerPreConnectEvent.java

@@ -0,0 +1,86 @@
+package com.velocitypowered.api.event.player;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.event.ResultedEvent;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import java.util.Optional;
+
+/**
+ * This event is fired before the player connects to a server.
+ */
+public class ServerPreConnectEvent implements ResultedEvent<ServerPreConnectEvent.ServerResult> {
+    private final Player player;
+    private ServerResult result;
+
+    public ServerPreConnectEvent(Player player, ServerResult result) {
+        this.player = Preconditions.checkNotNull(player, "player");
+        this.result = Preconditions.checkNotNull(result, "result");
+    }
+
+    public Player getPlayer() {
+        return player;
+    }
+
+    @Override
+    public ServerResult getResult() {
+        return result;
+    }
+
+    @Override
+    public void setResult(@NonNull ServerResult result) {
+        this.result = Preconditions.checkNotNull(result, "result");
+    }
+
+    @Override
+    public String toString() {
+        return "ServerPreConnectEvent{" +
+                "player=" + player +
+                ", result=" + result +
+                '}';
+    }
+
+    /**
+     * Represents the result of the {@link ServerPreConnectEvent}.
+     */
+    public static class ServerResult implements ResultedEvent.Result {
+        private static final ServerResult DENIED = new ServerResult(false, null);
+
+        private final boolean allowed;
+        private final ServerInfo info;
+
+        private ServerResult(boolean allowed, @Nullable ServerInfo info) {
+            this.allowed = allowed;
+            this.info = info;
+        }
+
+        @Override
+        public boolean isAllowed() {
+            return allowed;
+        }
+
+        public Optional<ServerInfo> getInfo() {
+            return Optional.ofNullable(info);
+        }
+
+        @Override
+        public String toString() {
+            if (!allowed) {
+                return "denied";
+            }
+            return "allowed: connect to " + info.getName();
+        }
+
+        public static ServerResult denied() {
+            return DENIED;
+        }
+
+        public static ServerResult allowed(ServerInfo server) {
+            Preconditions.checkNotNull(server, "server");
+            return new ServerResult(true, server);
+        }
+    }
+}

api/src/main/java/com/velocitypowered/api/event/player/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides events for handling actions performed by players.
+ */
+package com.velocitypowered.api.event.player;

api/src/main/java/com/velocitypowered/api/event/proxy/ProxyInitializeEvent.java

@@ -0,0 +1,11 @@
+package com.velocitypowered.api.event.proxy;
+
+/**
+ * This event is fired by the proxy after plugins have been loaded but before the proxy starts accepting connections.
+ */
+public class ProxyInitializeEvent {
+    @Override
+    public String toString() {
+        return "ProxyInitializeEvent";
+    }
+}

api/src/main/java/com/velocitypowered/api/event/proxy/ProxyPingEvent.java

@@ -0,0 +1,38 @@
+package com.velocitypowered.api.event.proxy;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.InboundConnection;
+import com.velocitypowered.api.proxy.server.ServerPing;
+
+/**
+ * This event is fired when a server list ping request is sent by a remote client.
+ */
+public class ProxyPingEvent {
+    private final InboundConnection connection;
+    private ServerPing ping;
+
+    public ProxyPingEvent(InboundConnection connection, ServerPing ping) {
+        this.connection = Preconditions.checkNotNull(connection, "connection");
+        this.ping = Preconditions.checkNotNull(ping, "ping");
+    }
+
+    public InboundConnection getConnection() {
+        return connection;
+    }
+
+    public ServerPing getPing() {
+        return ping;
+    }
+
+    public void setPing(ServerPing ping) {
+        this.ping = Preconditions.checkNotNull(ping, "ping");
+    }
+
+    @Override
+    public String toString() {
+        return "ProxyPingEvent{" +
+                "connection=" + connection +
+                ", ping=" + ping +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/event/proxy/ProxyShutdownEvent.java

@@ -0,0 +1,12 @@
+package com.velocitypowered.api.event.proxy;
+
+/**
+ * This event is fired by the proxy after the proxy has stopped accepting connections but before the proxy process
+ * exits.
+ */
+public class ProxyShutdownEvent {
+    @Override
+    public String toString() {
+        return "ProxyShutdownEvent";
+    }
+}

api/src/main/java/com/velocitypowered/api/event/proxy/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides events for handling the lifecycle of the proxy.
+ */
+package com.velocitypowered.api.event.proxy;

api/src/main/java/com/velocitypowered/api/package-info.java

@@ -1,5 +0,0 @@
-package com.velocitypowered.api;
-
-/**
- * Welcome to the Velocity API documentation.
- */

api/src/main/java/com/velocitypowered/api/permission/PermissionFunction.java

@@ -0,0 +1,33 @@
+package com.velocitypowered.api.permission;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Function that calculates the permission settings for a given
+ * {@link PermissionSubject}.
+ */
+@FunctionalInterface
+public interface PermissionFunction {
+    /**
+     * A permission function that always returns {@link Tristate#TRUE}.
+     */
+    PermissionFunction ALWAYS_TRUE = p -> Tristate.TRUE;
+
+    /**
+     * A permission function that always returns {@link Tristate#FALSE}.
+     */
+    PermissionFunction ALWAYS_FALSE = p -> Tristate.FALSE;
+
+    /**
+     * A permission function that always returns {@link Tristate#UNDEFINED}.
+     */
+    PermissionFunction ALWAYS_UNDEFINED = p -> Tristate.UNDEFINED;
+
+    /**
+     * Gets the subjects setting for a particular permission.
+     *
+     * @param permission the permission
+     * @return the value the permission is set to
+     */
+    @NonNull Tristate getPermissionSetting(@NonNull String permission);
+}

api/src/main/java/com/velocitypowered/api/permission/PermissionProvider.java

@@ -0,0 +1,17 @@
+package com.velocitypowered.api.permission;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Provides {@link PermissionFunction}s for {@link PermissionSubject}s.
+ */
+@FunctionalInterface
+public interface PermissionProvider {
+    /**
+     * Creates a {@link PermissionFunction} for the subject.
+     *
+     * @param subject the subject
+     * @return the function
+     */
+    @NonNull PermissionFunction createFunction(@NonNull PermissionSubject subject);
+}

api/src/main/java/com/velocitypowered/api/permission/PermissionSubject.java

@@ -0,0 +1,16 @@
+package com.velocitypowered.api.permission;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+/**
+ * Represents a object that has a set of queryable permissions.
+ */
+public interface PermissionSubject {
+    /**
+     * Determines whether or not the subject has a particular permission.
+     *
+     * @param permission the permission to check for
+     * @return whether or not the subject has the permission
+     */
+    boolean hasPermission(@NonNull String permission);
+}

api/src/main/java/com/velocitypowered/api/permission/Tristate.java

@@ -0,0 +1,74 @@
+package com.velocitypowered.api.permission;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/**
+ * Represents three different states of a setting.
+ *
+ * <p>Possible values:</p>
+ * <p></p>
+ * <ul>
+ *     <li>{@link #TRUE} - a positive setting</li>
+ *     <li>{@link #FALSE} - a negative (negated) setting</li>
+ *     <li>{@link #UNDEFINED} - a non-existent setting</li>
+ * </ul>
+ */
+public enum Tristate {
+
+    /**
+     * A value indicating a positive setting
+     */
+    TRUE(true),
+
+    /**
+     * A value indicating a negative (negated) setting
+     */
+    FALSE(false),
+
+    /**
+     * A value indicating a non-existent setting
+     */
+    UNDEFINED(false);
+
+    /**
+     * Returns a {@link Tristate} from a boolean
+     *
+     * @param val the boolean value
+     * @return {@link #TRUE} or {@link #FALSE}, if the value is <code>true</code> or <code>false</code>, respectively.
+     */
+    public static @NonNull Tristate fromBoolean(boolean val) {
+        return val ? TRUE : FALSE;
+    }
+
+    /**
+     * Returns a {@link Tristate} from a nullable boolean.
+     *
+     * <p>Unlike {@link #fromBoolean(boolean)}, this method returns {@link #UNDEFINED}
+     * if the value is null.</p>
+     *
+     * @param val the boolean value
+     * @return {@link #UNDEFINED}, {@link #TRUE} or {@link #FALSE}, if the value
+     *         is <code>null</code>, <code>true</code> or <code>false</code>, respectively.
+     */
+    public static @NonNull Tristate fromNullableBoolean(@Nullable Boolean val) {
+        return val == null ? UNDEFINED : val ? TRUE : FALSE;
+    }
+
+    private final boolean booleanValue;
+
+    Tristate(boolean booleanValue) {
+        this.booleanValue = booleanValue;
+    }
+
+    /**
+     * Returns the value of the Tristate as a boolean.
+     *
+     * <p>A value of {@link #UNDEFINED} converts to false.</p>
+     *
+     * @return a boolean representation of the Tristate.
+     */
+    public boolean asBoolean() {
+        return this.booleanValue;
+    }
+}

api/src/main/java/com/velocitypowered/api/permission/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides the basic building blocks for a custom permission system.
+ */
+package com.velocitypowered.api.permission;

api/src/main/java/com/velocitypowered/api/plugin/Dependency.java

@@ -0,0 +1,30 @@
+package com.velocitypowered.api.plugin;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Represents a dependency for a {@link Plugin}
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({})
+public @interface Dependency {
+    /**
+     * The plugin ID of the dependency.
+     *
+     * @return The dependency plugin ID
+     * @see Plugin#id()
+     */
+    String id();
+
+    // TODO Add required version field
+
+    /**
+     * If this dependency is optional for the plugin to work. By default
+     * this is {@code false}.
+     *
+     * @return true if the dependency is optional for the plugin to work
+     */
+    boolean optional() default false;
+}

api/src/main/java/com/velocitypowered/api/plugin/InvalidPluginException.java

@@ -0,0 +1,19 @@
+package com.velocitypowered.api.plugin;
+
+public class InvalidPluginException extends Exception {
+    public InvalidPluginException() {
+        super();
+    }
+
+    public InvalidPluginException(String message) {
+        super(message);
+    }
+
+    public InvalidPluginException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public InvalidPluginException(Throwable cause) {
+        super(cause);
+    }
+}

api/src/main/java/com/velocitypowered/api/plugin/Plugin.java

@@ -0,0 +1,66 @@
+package com.velocitypowered.api.plugin;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation used to describe a Velocity plugin.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface Plugin {
+    /**
+     * The ID of the plugin. This ID should be unique as to
+     * not conflict with other plugins.
+     *
+     * The plugin ID must match the {@link PluginDescription#ID_PATTERN}.
+     *
+     * @return the ID for this plugin
+     */
+    String id();
+
+    /**
+     * The human readable name of the plugin as to be used in descriptions and
+     * similar things.
+     *
+     * @return The plugin name, or an empty string if unknown
+     */
+    String name() default "";
+
+    /**
+     * The version of the plugin.
+     *
+     * @return the version of the plugin, or an empty string if unknown
+     */
+    String version() default "";
+
+    /**
+     * The description of the plugin, explaining what it can be used for.
+     *
+     * @return The plugin description, or an empty string if unknown
+     */
+    String description() default "";
+
+    /**
+     * The URL or website of the plugin.
+     *
+     * @return The plugin url, or an empty string if unknown
+     */
+    String url() default "";
+
+    /**
+     * The author of the plugin.
+     *
+     * @return the plugin's author, or empty if unknown
+     */
+    String[] authors() default "";
+
+    /**
+     * The dependencies required to load before this plugin.
+     *
+     * @return the plugin dependencies
+     */
+    Dependency[] dependencies() default {};
+}

api/src/main/java/com/velocitypowered/api/plugin/PluginContainer.java

@@ -0,0 +1,26 @@
+package com.velocitypowered.api.plugin;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.util.Optional;
+
+/**
+ * A wrapper around a plugin loaded by the proxy.
+ */
+public interface PluginContainer {
+    /**
+     * Returns the plugin's description.
+     *
+     * @return the plugin's description
+     */
+    @NonNull PluginDescription getDescription();
+
+    /**
+     * Returns the created plugin if it is available.
+     *
+     * @return the instance if available
+     */
+    default Optional<?> getInstance() {
+        return Optional.empty();
+    }
+}

api/src/main/java/com/velocitypowered/api/plugin/PluginDescription.java

@@ -0,0 +1,106 @@
+package com.velocitypowered.api.plugin;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.velocitypowered.api.plugin.meta.PluginDependency;
+
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.List;
+import java.util.Optional;
+import java.util.regex.Pattern;
+
+/**
+ * Represents metadata for a specific version of a plugin.
+ */
+public interface PluginDescription {
+    /**
+     * The pattern plugin IDs must match. Plugin IDs may only contain
+     * alphanumeric characters, dashes or underscores, must start with
+     * an alphabetic character and cannot be longer than 64 characters.
+     */
+    Pattern ID_PATTERN = Pattern.compile("[a-z][a-z0-9-_]{0,63}");
+
+    /**
+     * Gets the qualified ID of the {@link Plugin} within this container.
+     *
+     * @return the plugin ID
+     * @see Plugin#id()
+     */
+    String getId();
+
+    /**
+     * Gets the name of the {@link Plugin} within this container.
+     *
+     * @return an {@link Optional} with the plugin name, may be empty
+     * @see Plugin#name()
+     */
+    default Optional<String> getName() {
+        return Optional.empty();
+    }
+
+    /**
+     * Gets the version of the {@link Plugin} within this container.
+     *
+     * @return an {@link Optional} with the plugin version, may be empty
+     * @see Plugin#version()
+     */
+    default Optional<String> getVersion() {
+        return Optional.empty();
+    }
+
+    /**
+     * Gets the description of the {@link Plugin} within this container.
+     *
+     * @return an {@link Optional} with the plugin description, may be empty
+     * @see Plugin#description()
+     */
+    default Optional<String> getDescription() {
+        return Optional.empty();
+    }
+
+    /**
+     * Gets the url or website of the {@link Plugin} within this container.
+     *
+     * @return an {@link Optional} with the plugin url, may be empty
+     * @see Plugin#url()
+     */
+    default Optional<String> getUrl() {
+        return Optional.empty();
+    }
+
+    /**
+     * Gets the authors of the {@link Plugin} within this container.
+     *
+     * @return the plugin authors, may be empty
+     * @see Plugin#authors()
+     */
+    default List<String> getAuthors() {
+        return ImmutableList.of();
+    }
+
+    /**
+     * Gets a {@link Collection} of all dependencies of the {@link Plugin} within
+     * this container.
+     *
+     * @return the plugin dependencies, can be empty
+     * @see Plugin#dependencies()
+     */
+    default Collection<PluginDependency> getDependencies() {
+        return ImmutableSet.of();
+    }
+
+    default Optional<PluginDependency> getDependency(String id) {
+        return Optional.empty();
+    }
+
+    /**
+     * Returns the source the plugin was loaded from.
+     *
+     * @return the source the plugin was loaded from or {@link Optional#empty()}
+     *         if unknown
+     */
+    default Optional<Path> getSource() {
+        return Optional.empty();
+    }
+}

api/src/main/java/com/velocitypowered/api/plugin/PluginManager.java

@@ -0,0 +1,55 @@
+package com.velocitypowered.api.plugin;
+
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.Optional;
+import java.util.logging.Logger;
+
+/**
+ * The class that manages plugins. This manager can retrieve
+ * {@link PluginContainer}s from {@link Plugin} instances, getting
+ * {@link Logger}s, etc.
+ */
+public interface PluginManager {
+    /**
+     * Gets the plugin container from an instance.
+     *
+     * @param instance the instance
+     * @return the container
+     */
+    @NonNull Optional<PluginContainer> fromInstance(@NonNull Object instance);
+
+    /**
+     * Retrieves a {@link PluginContainer} based on its ID.
+     *
+     * @param id the plugin ID
+     * @return the plugin, if available
+     */
+    @NonNull Optional<PluginContainer> getPlugin(@NonNull String id);
+
+    /**
+     * Gets a {@link Collection} of all {@link PluginContainer}s.
+     *
+     * @return the plugins
+     */
+    @NonNull Collection<PluginContainer> getPlugins();
+
+    /**
+     * Checks if a plugin is loaded based on its ID.
+     *
+     * @param id the id of the {@link Plugin}
+     * @return {@code true} if loaded
+     */
+    boolean isLoaded(@NonNull String id);
+
+    /**
+     * Adds the specified {@code path} to the plugin classpath.
+     *
+     * @param plugin the plugin
+     * @param path the path to the JAR you want to inject into the classpath
+     * @throws UnsupportedOperationException if the operation is not applicable to this plugin
+     */
+    void addToClasspath(@NonNull Object plugin, @NonNull Path path);
+}

api/src/main/java/com/velocitypowered/api/plugin/annotation/DataDirectory.java

@@ -0,0 +1,18 @@
+package com.velocitypowered.api.plugin.annotation;
+
+import com.google.inject.BindingAnnotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * This annotation requests that Velocity inject a {@link java.nio.file.Path} instance with a plugin-specific data
+ * directory.
+ */
+@Target({ElementType.FIELD, ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+@BindingAnnotation
+public @interface DataDirectory {
+}

api/src/main/java/com/velocitypowered/api/plugin/annotation/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides annotations to handle injecting dependencies for plugins.
+ */
+package com.velocitypowered.api.plugin.annotation;

api/src/main/java/com/velocitypowered/api/plugin/meta/PluginDependency.java

@@ -0,0 +1,79 @@
+package com.velocitypowered.api.plugin.meta;
+
+import javax.annotation.Nullable;
+
+import java.util.Objects;
+import java.util.Optional;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Strings.emptyToNull;
+
+/**
+ * Represents a dependency on another plugin.
+ */
+public final class PluginDependency {
+    private final String id;
+    @Nullable private final String version;
+
+    private final boolean optional;
+
+    public PluginDependency(String id, @Nullable String version, boolean optional) {
+        this.id = checkNotNull(id, "id");
+        checkArgument(!id.isEmpty(), "id cannot be empty");
+        this.version = emptyToNull(version);
+        this.optional = optional;
+    }
+
+    /**
+     * Returns the plugin ID of this {@link PluginDependency}
+     *
+     * @return the plugin ID
+     */
+    public String getId() {
+        return id;
+    }
+
+    /**
+     * Returns the version this {@link PluginDependency} should match.
+     *
+     * @return an {@link Optional} with the plugin version, may be empty
+     */
+    public Optional<String> getVersion() {
+        return Optional.ofNullable(version);
+    }
+
+    /**
+     * Returns whether the dependency is optional for the plugin to work
+     * correctly.
+     *
+     * @return true if dependency is optional
+     */
+    public boolean isOptional() {
+        return optional;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PluginDependency that = (PluginDependency) o;
+        return optional == that.optional &&
+                Objects.equals(id, that.id) &&
+                Objects.equals(version, that.version);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, version, optional);
+    }
+
+    @Override
+    public String toString() {
+        return "PluginDependency{" +
+                "id='" + id + '\'' +
+                ", version='" + version + '\'' +
+                ", optional=" + optional +
+                '}';
+    }
+}

api/src/main/java/com/velocitypowered/api/plugin/meta/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides metadata for plugins.
+ */
+package com.velocitypowered.api.plugin.meta;

api/src/main/java/com/velocitypowered/api/plugin/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides the Velocity plugin API.
+ */
+package com.velocitypowered.api.plugin;

api/src/main/java/com/velocitypowered/api/proxy/ConnectionRequestBuilder.java

@@ -1,28 +1,29 @@
 package com.velocitypowered.api.proxy;
 
-import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.api.proxy.server.ServerInfo;
 import net.kyori.text.Component;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 /**
- * Represents a connection request. A connection request is created using {@link Player#createConnectionRequest(ServerInfo)}
- * and is used to allow a plugin to compose and request a connection to another Minecraft server using a fluent API.
+ * Provides a fluent interface to compose and send a connection request to another server behind the proxy. A connection
+ * request is created using {@link Player#createConnectionRequest(ServerInfo)}.
  */
 public interface ConnectionRequestBuilder {
     /**
      * Returns the server that this connection request represents.
      * @return the server this request will connect to
      */
-    ServerInfo getServer();
+    @NonNull ServerInfo getServer();
 
     /**
      * Initiates the connection to the remote server and emits a result on the {@link CompletableFuture} after the user
      * has logged on. No messages will be communicated to the client: the user is responsible for all error handling.
      * @return a {@link CompletableFuture} representing the status of this connection
      */
-    CompletableFuture<Result> connect();
+    @NonNull CompletableFuture<Result> connect();
 
     /**
      * Initiates the connection to the remote server without waiting for a result. Velocity will use generic error
@@ -49,7 +50,7 @@ public interface ConnectionRequestBuilder {
         Status getStatus();
 
         /**
-         * Returns a reason for the failure to connect to the server. None may be provided.
+         * Returns an (optional) textual reason for the failure to connect to the server.
          * @return the reason why the user could not connect to the server
          */
         Optional<Component> getReason();

api/src/main/java/com/velocitypowered/api/proxy/InboundConnection.java

@@ -0,0 +1,33 @@
+package com.velocitypowered.api.proxy;
+
+import java.net.InetSocketAddress;
+import java.util.Optional;
+
+/**
+ * Represents an incoming connection to the proxy.
+ */
+public interface InboundConnection {
+    /**
+     * Returns the player's IP address.
+     * @return the player's IP
+     */
+    InetSocketAddress getRemoteAddress();
+
+    /**
+     * Returns the hostname that the user entered into the client, if applicable.
+     * @return the hostname from the client
+     */
+    Optional<InetSocketAddress> getVirtualHost();
+
+    /**
+     * Determine whether or not the player remains online.
+     * @return whether or not the player active
+     */
+    boolean isActive();
+
+    /**
+     * Returns the current protocol version this connection uses.
+     * @return the protocol version the connection uses
+     */
+    int getProtocolVersion();
+}

api/src/main/java/com/velocitypowered/api/proxy/Player.java

@@ -1,18 +1,20 @@
 package com.velocitypowered.api.proxy;
 
-import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.api.proxy.messages.ChannelMessageSink;
+import com.velocitypowered.api.proxy.messages.ChannelMessageSource;
+import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.api.util.MessagePosition;
 import net.kyori.text.Component;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
-import javax.annotation.Nonnull;
-import java.net.InetSocketAddress;
 import java.util.Optional;
 import java.util.UUID;
 
 /**
  * Represents a player who is connected to the proxy.
  */
-public interface Player {
+public interface Player extends CommandSource, InboundConnection, ChannelMessageSource, ChannelMessageSink {
     /**
      * Returns the player's current username.
      * @return the username
@@ -29,25 +31,13 @@ public interface Player {
      * Returns the server that the player is currently connected to.
      * @return an {@link Optional} the server that the player is connected to, which may be empty
      */
-    Optional<ServerInfo> getCurrentServer();
-
-    /**
-     * Returns the player's IP address.
-     * @return the player's IP
-     */
-    InetSocketAddress getRemoteAddress();
-
-    /**
-     * Determine whether or not the player remains online.
-     * @return whether or not the player active
-     */
-    boolean isActive();
+    Optional<ServerConnection> getCurrentServer();
     
     /**
      * Sends a chat message to the player's client.
      * @param component the chat message to send
      */
-    default void sendMessage(@Nonnull Component component) {
+    default void sendMessage(@NonNull Component component) {
         sendMessage(component, MessagePosition.CHAT);
     }
 
@@ -56,12 +46,31 @@ public interface Player {
      * @param component the chat message to send
      * @param position the position for the message
      */
-    void sendMessage(@Nonnull Component component, @Nonnull MessagePosition position);
+    void sendMessage(@NonNull Component component, @NonNull MessagePosition position);
 
     /**
      * Creates a new connection request so that the player can connect to another server.
      * @param info the server to connect to
      * @return a new connection request
      */
-    ConnectionRequestBuilder createConnectionRequest(@Nonnull ServerInfo info);
+    ConnectionRequestBuilder createConnectionRequest(@NonNull ServerInfo info);
+
+    /**
+     * Sets the tab list header and footer for the player.
+     * @param header the header component
+     * @param footer the footer component
+     */
+    void setHeaderAndFooter(Component header, Component footer);
+
+    /**
+     * Clears the tab list header and footer for the player.
+     */
+    void clearHeaderAndFooter();
+
+    /**
+     * Disconnects the player with the specified reason. Once this method is called, further calls to other {@link Player}
+     * methods will become undefined.
+     * @param reason component with the reason
+     */
+    void disconnect(Component reason);
 }

api/src/main/java/com/velocitypowered/api/proxy/ProxyServer.java

@@ -0,0 +1,110 @@
+package com.velocitypowered.api.proxy;
+
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.api.command.CommandManager;
+import com.velocitypowered.api.event.EventManager;
+import com.velocitypowered.api.plugin.PluginManager;
+import com.velocitypowered.api.proxy.messages.ChannelRegistrar;
+import com.velocitypowered.api.scheduler.Scheduler;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+
+import java.util.Collection;
+import java.util.Optional;
+import java.util.UUID;
+
+/**
+ * Provides an interface to a Minecraft server proxy.
+ */
+public interface ProxyServer {
+    /**
+     * Retrieves the player currently connected to this proxy by their Minecraft username. The search is case-insensitive.
+     * @param username the username to search for
+     * @return an {@link Optional} with the player, which may be empty
+     */
+    Optional<Player> getPlayer(String username);
+
+    /**
+     * Retrieves the player currently connected to this proxy by their Minecraft UUID.
+     * @param uuid the UUID
+     * @return an {@link Optional} with the player, which may be empty
+     */
+    Optional<Player> getPlayer(UUID uuid);
+
+    /**
+     * Retrieves all players currently connected to this proxy. This call may or may not be a snapshot of all players
+     * online.
+     * @return the players online on this proxy
+     */
+    Collection<Player> getAllPlayers();
+
+    /**
+     * Returns the number of players currently connected to this proxy.
+     * @return the players on this proxy
+     */
+    int getPlayerCount();
+
+    /**
+     * Retrieves a registered {@link ServerInfo} instance by its name. The search is case-insensitive.
+     * @param name the name of the server
+     * @return the registered server, which may be empty
+     */
+    Optional<ServerInfo> getServerInfo(String name);
+
+    /**
+     * Retrieves all {@link ServerInfo}s registered with this proxy.
+     * @return the servers registered with this proxy
+     */
+    Collection<ServerInfo> getAllServers();
+
+    /**
+     * Registers a server with this proxy. A server with this name should not already exist.
+     * @param server the server to register
+     */
+    void registerServer(ServerInfo server);
+
+    /**
+     * Unregisters this server from the proxy.
+     * @param server the server to unregister
+     */
+    void unregisterServer(ServerInfo server);
+
+    /**
+     * Returns an instance of {@link CommandSource} that can be used to determine if the command is being invoked by
+     * the console or a console-like executor. Plugins that execute commands are strongly urged to implement their own
+     * {@link CommandSource} instead of using the console invoker.
+     * @return the console command invoker
+     */
+    CommandSource getConsoleCommandSource();
+
+    /**
+     * Gets the {@link PluginManager} instance.
+     *
+     * @return the plugin manager instance
+     */
+    PluginManager getPluginManager();
+
+    /**
+     * Gets the {@link EventManager} instance.
+     *
+     * @return the event manager instance
+     */
+    EventManager getEventManager();
+
+    /**
+     * Gets the {@link CommandManager} instance.
+     * @return the command manager
+     */
+    CommandManager getCommandManager();
+
+    /**
+     * Gets the {@link Scheduler} instance.
+     * @return the scheduler instance
+     */
+    Scheduler getScheduler();
+
+    /**
+     * Gets the {@link ChannelRegistrar} instance.
+     * @return the channel registrar
+     */
+    ChannelRegistrar getChannelRegistrar();
+}

api/src/main/java/com/velocitypowered/api/proxy/ServerConnection.java

@@ -0,0 +1,22 @@
+package com.velocitypowered.api.proxy;
+
+import com.velocitypowered.api.proxy.messages.ChannelMessageSink;
+import com.velocitypowered.api.proxy.messages.ChannelMessageSource;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+
+/**
+ * Represents a connection to a backend server from the proxy for a client.
+ */
+public interface ServerConnection extends ChannelMessageSource, ChannelMessageSink {
+    /**
+     * Returns the server that this connection is connected to.
+     * @return the server this connection is connected to
+     */
+    ServerInfo getServerInfo();
+
+    /**
+     * Returns the player that this connection is associated with.
+     * @return the player for this connection
+     */
+    Player getPlayer();
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/ChannelIdentifier.java

@@ -0,0 +1,12 @@
+package com.velocitypowered.api.proxy.messages;
+
+/**
+ * Represents a kind of channel identifier.
+ */
+public interface ChannelIdentifier {
+    /**
+     * Returns the textual representation of this identifier.
+     * @return the textual representation of the identifier
+     */
+    String getId();
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/ChannelMessageSink.java

@@ -0,0 +1,13 @@
+package com.velocitypowered.api.proxy.messages;
+
+/**
+ * Represents something that can send plugin messages.
+ */
+public interface ChannelMessageSink {
+    /**
+     * Sends a plugin message to this target.
+     * @param identifier the channel identifier to send the message on
+     * @param data the data to send
+     */
+    void sendPluginMessage(ChannelIdentifier identifier, byte[] data);
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/ChannelMessageSource.java

@@ -0,0 +1,7 @@
+package com.velocitypowered.api.proxy.messages;
+
+/**
+ * A marker interface that indicates a source of plugin messages.
+ */
+public interface ChannelMessageSource {
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/ChannelRegistrar.java

@@ -0,0 +1,20 @@
+package com.velocitypowered.api.proxy.messages;
+
+/**
+ * Represents an interface to register and unregister {@link MessageHandler} instances for handling plugin messages from
+ * the client or the server.
+ */
+public interface ChannelRegistrar {
+    /**
+     * Registers the specified message handler to listen for plugin messages on the specified channels.
+     * @param handler the handler to register
+     * @param identifiers the channel identifiers to register
+     */
+    void register(MessageHandler handler, ChannelIdentifier... identifiers);
+
+    /**
+     * Unregisters the handler for the specified channel.
+     * @param identifiers the identifiers to unregister
+     */
+    void unregister(ChannelIdentifier... identifiers);
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/ChannelSide.java

@@ -0,0 +1,15 @@
+package com.velocitypowered.api.proxy.messages;
+
+/**
+ * Represents from "which side" of the proxy the plugin message came from.
+ */
+public enum ChannelSide {
+    /**
+     * The plugin message came from a server that a client was connected to.
+     */
+    FROM_SERVER,
+    /**
+     * The plugin message came from the client.
+     */
+    FROM_CLIENT
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/LegacyChannelIdentifier.java

@@ -0,0 +1,48 @@
+package com.velocitypowered.api.proxy.messages;
+
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+
+import java.util.Objects;
+
+/**
+ * Reperesents a legacy channel identifier (for Minecraft 1.12 and below). For modern 1.13 plugin messages, please see
+ * {@link MinecraftChannelIdentifier}. This class is immutable and safe for multi-threaded use.
+ */
+public final class LegacyChannelIdentifier implements ChannelIdentifier {
+    private final String name;
+
+    public LegacyChannelIdentifier(String name) {
+        Preconditions.checkArgument(!Strings.isNullOrEmpty(name), "provided name is empty");
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return "LegacyChannelIdentifier{" +
+                "name='" + name + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        LegacyChannelIdentifier that = (LegacyChannelIdentifier) o;
+        return Objects.equals(name, that.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name);
+    }
+
+    @Override
+    public String getId() {
+        return name;
+    }
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/MessageHandler.java

@@ -0,0 +1,28 @@
+package com.velocitypowered.api.proxy.messages;
+
+/**
+ * Represents a handler for handling plugin messages.
+ */
+public interface MessageHandler {
+    /**
+     * Handles an incoming plugin message.
+     * @param source the source of the plugin message
+     * @param side from where the plugin message originated
+     * @param identifier the channel on which the message was sent
+     * @param data the data inside the plugin message
+     * @return a {@link ForwardStatus} indicating whether or not to forward this plugin message on
+     */
+    ForwardStatus handle(ChannelMessageSource source, ChannelSide side, ChannelIdentifier identifier, byte[] data);
+
+    enum ForwardStatus {
+        /**
+         * Forwards this plugin message on to the client or server, depending on the {@link ChannelSide} it originated
+         * from.
+         */
+        FORWARD,
+        /**
+         * Discard the plugin message and do not forward it on.
+         */
+        HANDLED
+    }
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/MinecraftChannelIdentifier.java

@@ -0,0 +1,81 @@
+package com.velocitypowered.api.proxy.messages;
+
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+/**
+ * Represents a Minecraft 1.13+ channel identifier. This class is immutable and safe for multi-threaded use.
+ */
+public final class MinecraftChannelIdentifier implements ChannelIdentifier {
+    private static final Pattern VALID_IDENTIFIER_REGEX = Pattern.compile("[a-z0-9\\-_]+");
+
+    private final String namespace;
+    private final String name;
+
+    private MinecraftChannelIdentifier(String namespace, String name) {
+        this.namespace = namespace;
+        this.name = name;
+    }
+
+    /**
+     * Creates an identifier in the default namespace ({@code minecraft}). Plugins are strongly encouraged to provide
+     * their own namespace.
+     * @param name the name in the default namespace to use
+     * @return a new channel identifier
+     */
+    public static MinecraftChannelIdentifier forDefaultNamespace(String name) {
+        return new MinecraftChannelIdentifier("minecraft", name);
+    }
+
+    /**
+     * Creates an identifier in the specified namespace.
+     * @param namespace the namespace to use
+     * @param name the channel name inside the specified namespace
+     * @return a new channel identifier
+     */
+    public static MinecraftChannelIdentifier create(String namespace, String name) {
+        Preconditions.checkArgument(!Strings.isNullOrEmpty(namespace), "namespace is null or empty");
+        Preconditions.checkArgument(!Strings.isNullOrEmpty(name), "namespace is null or empty");
+        Preconditions.checkArgument(VALID_IDENTIFIER_REGEX.matcher(namespace).matches(), "namespace is not valid");
+        Preconditions.checkArgument(VALID_IDENTIFIER_REGEX.matcher(name).matches(), "name is not valid");
+        return new MinecraftChannelIdentifier(namespace, name);
+    }
+
+    public String getNamespace() {
+        return namespace;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return "MinecraftChannelIdentifier{" +
+                "namespace='" + namespace + '\'' +
+                ", name='" + name + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        MinecraftChannelIdentifier that = (MinecraftChannelIdentifier) o;
+        return Objects.equals(namespace, that.namespace) &&
+                Objects.equals(name, that.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(namespace, name);
+    }
+
+    @Override
+    public String getId() {
+        return namespace + ":" + name;
+    }
+}

api/src/main/java/com/velocitypowered/api/proxy/messages/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides an interface to receive, handle, and send plugin messages on the proxy from clients and servers.
+ */
+package com.velocitypowered.api.proxy.messages;

api/src/main/java/com/velocitypowered/api/proxy/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides an interface to interact with the proxy at a low level.
+ */
+package com.velocitypowered.api.proxy;

api/src/main/java/com/velocitypowered/api/proxy/server/ServerInfo.java

@@ -1,6 +1,7 @@
-package com.velocitypowered.api.server;
+package com.velocitypowered.api.proxy.server;
 
 import com.google.common.base.Preconditions;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.net.InetSocketAddress;
 import java.util.Objects;
@@ -9,24 +10,24 @@ import java.util.Objects;
  * ServerInfo represents a server that a player can connect to. This object is immutable and safe for concurrent access.
  */
 public final class ServerInfo {
-    private final String name;
-    private final InetSocketAddress address;
+    private final @NonNull String name;
+    private final @NonNull InetSocketAddress address;
 
     /**
      * Creates a new ServerInfo object.
      * @param name the name for the server
      * @param address the address of the server to connect to
      */
-    public ServerInfo(String name, InetSocketAddress address) {
+    public ServerInfo(@NonNull String name, @NonNull InetSocketAddress address) {
         this.name = Preconditions.checkNotNull(name, "name");
         this.address = Preconditions.checkNotNull(address, "address");
     }
 
-    public final String getName() {
+    public final @NonNull String getName() {
         return name;
     }
 
-    public final InetSocketAddress getAddress() {
+    public final @NonNull InetSocketAddress getAddress() {
         return address;
     }
 

api/src/main/java/com/velocitypowered/api/proxy/server/ServerPing.java

@@ -0,0 +1,244 @@
+package com.velocitypowered.api.proxy.server;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.util.Favicon;
+import net.kyori.text.Component;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import java.util.*;
+
+/**
+ * Represents a 1.7 and above server list ping response. This class is immutable.
+ */
+public class ServerPing {
+    private final Version version;
+    private final Players players;
+    private final Component description;
+    private final @Nullable Favicon favicon;
+
+    public ServerPing(@NonNull Version version, @NonNull Players players, @NonNull Component description, @Nullable Favicon favicon) {
+        this.version = Preconditions.checkNotNull(version, "version");
+        this.players = Preconditions.checkNotNull(players, "players");
+        this.description = Preconditions.checkNotNull(description, "description");
+        this.favicon = favicon;
+    }
+
+    public Version getVersion() {
+        return version;
+    }
+
+    public Players getPlayers() {
+        return players;
+    }
+
+    public Component getDescription() {
+        return description;
+    }
+
+    public Optional<Favicon> getFavicon() {
+        return Optional.ofNullable(favicon);
+    }
+
+    @Override
+    public String toString() {
+        return "ServerPing{" +
+                "version=" + version +
+                ", players=" + players +
+                ", description=" + description +
+                ", favicon='" + favicon + '\'' +
+                '}';
+    }
+
+    public Builder asBuilder() {
+        Builder builder = new Builder();
+        builder.version = version;
+        builder.onlinePlayers = players.online;
+        builder.maximumPlayers = players.max;
+        builder.samplePlayers.addAll(players.sample);
+        builder.description = description;
+        builder.favicon = favicon;
+        return builder;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * A builder for {@link ServerPing} objects.
+     */
+    public static class Builder {
+        private Version version;
+        private int onlinePlayers;
+        private int maximumPlayers;
+        private final List<SamplePlayer> samplePlayers = new ArrayList<>();
+        private Component description;
+        private Favicon favicon;
+
+        private Builder() {
+
+        }
+
+        public Builder version(Version version) {
+            this.version = Preconditions.checkNotNull(version, "version");
+            return this;
+        }
+
+        public Builder onlinePlayers(int onlinePlayers) {
+            this.onlinePlayers = onlinePlayers;
+            return this;
+        }
+
+        public Builder maximumPlayers(int maximumPlayers) {
+            this.maximumPlayers = maximumPlayers;
+            return this;
+        }
+
+        public Builder samplePlayers(SamplePlayer... players) {
+            this.samplePlayers.addAll(Arrays.asList(players));
+            return this;
+        }
+
+        public Builder clearSamplePlayers() {
+            this.samplePlayers.clear();
+            return this;
+        }
+
+        public Builder description(Component description) {
+            this.description = Preconditions.checkNotNull(description, "description");
+            return this;
+        }
+
+        public Builder favicon(Favicon favicon) {
+            this.favicon = Preconditions.checkNotNull(favicon, "favicon");
+            return this;
+        }
+
+        public ServerPing build() {
+            return new ServerPing(version, new Players(onlinePlayers, maximumPlayers, samplePlayers), description, favicon);
+        }
+
+        public Version getVersion() {
+            return version;
+        }
+
+        public int getOnlinePlayers() {
+            return onlinePlayers;
+        }
+
+        public int getMaximumPlayers() {
+            return maximumPlayers;
+        }
+
+        public List<SamplePlayer> getSamplePlayers() {
+            return samplePlayers;
+        }
+
+        public Component getDescription() {
+            return description;
+        }
+
+        public Favicon getFavicon() {
+            return favicon;
+        }
+
+        @Override
+        public String toString() {
+            return "Builder{" +
+                    "version=" + version +
+                    ", onlinePlayers=" + onlinePlayers +
+                    ", maximumPlayers=" + maximumPlayers +
+                    ", samplePlayers=" + samplePlayers +
+                    ", description=" + description +
+                    ", favicon=" + favicon +
+                    '}';
+        }
+    }
+
+    public static class Version {
+        private final int protocol;
+        private final String name;
+
+        public Version(int protocol, String name) {
+            this.protocol = protocol;
+            this.name = name;
+        }
+
+        public int getProtocol() {
+            return protocol;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        @Override
+        public String toString() {
+            return "Version{" +
+                    "protocol=" + protocol +
+                    ", name='" + name + '\'' +
+                    '}';
+        }
+    }
+
+    public static class Players {
+        private final int online;
+        private final int max;
+        private final List<SamplePlayer> sample;
+
+        public Players(int online, int max, List<SamplePlayer> sample) {
+            this.online = online;
+            this.max = max;
+            this.sample = ImmutableList.copyOf(sample);
+        }
+
+        public int getOnline() {
+            return online;
+        }
+
+        public int getMax() {
+            return max;
+        }
+
+        public List<SamplePlayer> getSample() {
+            return sample;
+        }
+
+        @Override
+        public String toString() {
+            return "Players{" +
+                    "online=" + online +
+                    ", max=" + max +
+                    ", sample=" + sample +
+                    '}';
+        }
+    }
+
+    public static class SamplePlayer {
+        private final String name;
+        private final UUID id;
+
+        public SamplePlayer(String name, UUID id) {
+            this.name = name;
+            this.id = id;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public UUID getId() {
+            return id;
+        }
+
+        @Override
+        public String toString() {
+            return "SamplePlayer{" +
+                    "name='" + name + '\'' +
+                    ", id=" + id +
+                    '}';
+        }
+    }
+}

api/src/main/java/com/velocitypowered/api/proxy/server/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides utilities to handle server information.
+ */
+package com.velocitypowered.api.proxy.server;

api/src/main/java/com/velocitypowered/api/scheduler/ScheduledTask.java

@@ -0,0 +1,24 @@
+package com.velocitypowered.api.scheduler;
+
+/**
+ * Represents a task that is scheduled to run on the proxy.
+ */
+public interface ScheduledTask {
+    /**
+     * Returns the plugin that scheduled this task.
+     * @return the plugin that scheduled this task
+     */
+    Object plugin();
+
+    /**
+     * Returns the current status of this task.
+     * @return the current status of this task
+     */
+    TaskStatus status();
+
+    /**
+     * Cancels this task. If the task is already running, the thread in which it is running will be interrupted.
+     * If the task is not currently running, Velocity will terminate it safely.
+     */
+    void cancel();
+}

api/src/main/java/com/velocitypowered/api/scheduler/Scheduler.java

@@ -0,0 +1,55 @@
+package com.velocitypowered.api.scheduler;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Represents a scheduler to execute tasks on the proxy.
+ */
+public interface Scheduler {
+    /**
+     * Initializes a new {@link TaskBuilder} for creating a task on the proxy.
+     * @param plugin the plugin to request the task for
+     * @param runnable the task to run when scheduled
+     * @return the task builder
+     */
+    TaskBuilder buildTask(Object plugin, Runnable runnable);
+
+    /**
+     * Represents a fluent interface to schedule tasks on the proxy.
+     */
+    interface TaskBuilder {
+        /**
+         * Specifies that the task should delay its execution by the specified amount of time.
+         * @param time the time to delay by
+         * @param unit the unit of time for {@code time}
+         * @return this builder, for chaining
+         */
+        TaskBuilder delay(int time, TimeUnit unit);
+
+        /**
+         * Specifies that the task should continue running after waiting for the specified amount, until it is cancelled.
+         * @param time the time to delay by
+         * @param unit the unit of time for {@code time}
+         * @return this builder, for chaining
+         */
+        TaskBuilder repeat(int time, TimeUnit unit);
+
+        /**
+         * Clears the delay on this task.
+         * @return this builder, for chaining
+         */
+        TaskBuilder clearDelay();
+
+        /**
+         * Clears the repeat interval on this task.
+         * @return this builder, for chaining
+         */
+        TaskBuilder clearRepeat();
+
+        /**
+         * Schedules this task for execution.
+         * @return the scheduled task
+         */
+        ScheduledTask schedule();
+    }
+}

api/src/main/java/com/velocitypowered/api/scheduler/TaskStatus.java

@@ -0,0 +1,16 @@
+package com.velocitypowered.api.scheduler;
+
+public enum TaskStatus {
+    /**
+     * The task is scheduled and is currently running.
+     */
+    SCHEDULED,
+    /**
+     * The task was cancelled with {@link ScheduledTask#cancel()}.
+     */
+    CANCELLED,
+    /**
+     * The task has run to completion. This is applicable only for tasks without a repeat.
+     */
+    FINISHED
+}

api/src/main/java/com/velocitypowered/api/scheduler/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides utilities for scheduling tasks with a fluent builder.
+ */
+package com.velocitypowered.api.scheduler;

api/src/main/java/com/velocitypowered/api/util/Favicon.java

@@ -0,0 +1,89 @@
+package com.velocitypowered.api.util;
+
+import com.google.common.base.Preconditions;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Base64;
+import java.util.Objects;
+
+/**
+ * Represents a Minecraft server favicon. A Minecraft server favicon is a 64x64 image that can be displayed to a remote
+ * client that sends a Server List Ping packet, and is automatically displayed in the Minecraft client.
+ */
+public final class Favicon {
+    private final String base64Url;
+
+    /**
+     * Directly create a favicon using its Base64 URL directly. You are generally better served by the create() series
+     * of functions.
+     * @param base64Url the url for use with this favicon
+     */
+    public Favicon(@NonNull String base64Url) {
+        this.base64Url = Preconditions.checkNotNull(base64Url, "base64Url");
+    }
+
+    /**
+     * Returns the Base64-encoded URI for this image.
+     * @return a URL representing this favicon
+     */
+    public String getBase64Url() {
+        return base64Url;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Favicon favicon = (Favicon) o;
+        return Objects.equals(base64Url, favicon.base64Url);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(base64Url);
+    }
+
+    @Override
+    public String toString() {
+        return "Favicon{" +
+                "base64Url='" + base64Url + '\'' +
+                '}';
+    }
+
+    /**
+     * Creates a new {@code Favicon} from the specified {@code image}.
+     * @param image the image to use for the favicon
+     * @return the created {@link Favicon} instance
+     */
+    public static Favicon create(@NonNull BufferedImage image) {
+        Preconditions.checkNotNull(image, "image");
+        Preconditions.checkArgument(image.getWidth() == 64 && image.getHeight() == 64, "Image does not have" +
+                " 64x64 dimensions (found %sx%s)", image.getWidth(), image.getHeight());
+        ByteArrayOutputStream os = new ByteArrayOutputStream();
+        try {
+            ImageIO.write(image, "PNG", os);
+        } catch (IOException e) {
+            throw new AssertionError(e);
+        }
+        return new Favicon("data:image/png;base64," + Base64.getEncoder().encodeToString(os.toByteArray()));
+    }
+
+    /**
+     * Creates a new {@code Favicon} by reading the image from the specified {@code path}.
+     * @param path the path to the image to create a favicon for
+     * @return the created {@link Favicon} instance
+     * @throws IOException if the file could not be read from the path
+     */
+    public static Favicon create(@NonNull Path path) throws IOException {
+        try (InputStream stream = Files.newInputStream(path)) {
+            return create(ImageIO.read(stream));
+        }
+    }
+}

api/src/main/java/com/velocitypowered/api/util/GameProfile.java

@@ -1,20 +1,23 @@
-package com.velocitypowered.proxy.data;
+package com.velocitypowered.api.util;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
-import com.velocitypowered.proxy.util.UuidUtils;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.List;
 import java.util.UUID;
 
-public class GameProfile {
+/**
+ * Represents a Mojang game profile. This class is immutable.
+ */
+public final class GameProfile {
     private final String id;
     private final String name;
     private final List<Property> properties;
 
-    public GameProfile(String id, String name, List<Property> properties) {
-        this.id = id;
-        this.name = name;
+    public GameProfile(@NonNull String id, @NonNull String name, @NonNull List<Property> properties) {
+        this.id = Preconditions.checkNotNull(id, "id");
+        this.name = Preconditions.checkNotNull(name, "name");
         this.properties = ImmutableList.copyOf(properties);
     }
 
@@ -31,10 +34,15 @@ public class GameProfile {
     }
 
     public List<Property> getProperties() {
-        return ImmutableList.copyOf(properties);
+        return properties;
     }
 
-    public static GameProfile forOfflinePlayer(String username) {
+    /**
+     * Creates a game profile suitable for use in offline-mode.
+     * @param username the username to use
+     * @return the new offline-mode game profile
+     */
+    public static GameProfile forOfflinePlayer(@NonNull String username) {
         Preconditions.checkNotNull(username, "username");
         String id = UuidUtils.toUndashed(UuidUtils.generateOfflinePlayerUuid(username));
         return new GameProfile(id, username, ImmutableList.of());
@@ -49,15 +57,15 @@ public class GameProfile {
                 '}';
     }
 
-    public class Property {
+    public final class Property {
         private final String name;
         private final String value;
         private final String signature;
 
-        public Property(String name, String value, String signature) {
-            this.name = name;
-            this.value = value;
-            this.signature = signature;
+        public Property(@NonNull String name, @NonNull String value, @NonNull String signature) {
+            this.name = Preconditions.checkNotNull(name, "name");
+            this.value = Preconditions.checkNotNull(value, "value");
+            this.signature = Preconditions.checkNotNull(signature, "signature");
         }
 
         public String getName() {

api/src/main/java/com/velocitypowered/api/util/LegacyChatColorUtils.java

@@ -1,6 +1,7 @@
 package com.velocitypowered.api.util;
 
 import com.google.common.base.Preconditions;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.regex.Pattern;
 
@@ -25,7 +26,7 @@ public class LegacyChatColorUtils {
      * @param text the text to translate
      * @return the translated text
      */
-    public static String translate(char originalChar, String text) {
+    public static String translate(char originalChar, @NonNull String text) {
         Preconditions.checkNotNull(text, "text");
         char[] textChars = text.toCharArray();
         int foundSectionIdx = -1;
@@ -58,7 +59,7 @@ public class LegacyChatColorUtils {
      * @param text the text to remove color codes from
      * @return a new String without Minecraft color codes
      */
-    public static String removeFormatting(String text) {
+    public static String removeFormatting(@NonNull String text) {
         Preconditions.checkNotNull(text, "text");
         return CHAT_COLOR_MATCHER.matcher(text).replaceAll("");
     }

api/src/main/java/com/velocitypowered/api/util/UuidUtils.java

@@ -0,0 +1,50 @@
+package com.velocitypowered.api.util;
+
+import com.google.common.base.Preconditions;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+import java.util.UUID;
+
+/**
+ * Provides a small, useful selection of utilities for working with Minecraft UUIDs.
+ */
+public class UuidUtils {
+    private UuidUtils() {
+        throw new AssertionError();
+    }
+
+    /**
+     * Converts from an undashed Mojang-style UUID into a Java {@link UUID} object.
+     * @param string the string to convert
+     * @return the UUID object
+     */
+    public static @NonNull UUID fromUndashed(final @NonNull String string) {
+        Objects.requireNonNull(string, "string");
+        Preconditions.checkArgument(string.length() == 32, "Length is incorrect");
+        return new UUID(
+            Long.parseUnsignedLong(string.substring(0, 16), 16),
+            Long.parseUnsignedLong(string.substring(16), 16)
+        );
+    }
+
+    /**
+     * Converts from a Java {@link UUID} object into an undashed Mojang-style UUID.
+     * @param uuid the UUID to convert
+     * @return the undashed UUID
+     */
+    public static @NonNull String toUndashed(final @NonNull UUID uuid) {
+        Preconditions.checkNotNull(uuid, "uuid");
+        return Long.toUnsignedString(uuid.getMostSignificantBits(), 16) + Long.toUnsignedString(uuid.getLeastSignificantBits(), 16);
+    }
+
+    /**
+     * Generates a UUID for use for offline mode.
+     * @param username the username to use
+     * @return the offline mode UUID
+     */
+    public static @NonNull UUID generateOfflinePlayerUuid(@NonNull String username) {
+        return UUID.nameUUIDFromBytes(("OfflinePlayer:" + username).getBytes(StandardCharsets.UTF_8));
+    }
+}

api/src/main/java/com/velocitypowered/api/util/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Provides a selection of miscellaneous utilities for use by plugins and the proxy.
+ */
+package com.velocitypowered.api.util;

build.gradle

@@ -12,9 +12,21 @@ allprojects {
     ext {
         // dependency versions
         junitVersion = '5.3.0-M1'
+        slf4jVersion = '1.7.25'
         log4jVersion = '2.11.0'
         nettyVersion = '4.1.28.Final'
         guavaVersion = '25.1-jre'
+
+        getCurrentBranchName = {
+            new ByteArrayOutputStream().withStream { os ->
+                exec {
+                    executable = "git"
+                    args = ["rev-parse", "--abbrev-ref", "HEAD"]
+                    standardOutput = os
+                }
+                return os.toString().trim()
+            }
+        }
     }
 
     repositories {

native/src/main/java/com/velocitypowered/natives/util/Natives.java

@@ -41,12 +41,12 @@ public class Natives {
     public static final NativeCodeLoader<VelocityCompressorFactory> compressor = new NativeCodeLoader<>(
             ImmutableList.of(
                     new NativeCodeLoader.Variant<>(NativeCodeLoader.MACOS,
-                            copyAndLoadNative("/macosx/velocity-compress.dylib"), "native compression (macOS)",
+                            copyAndLoadNative("/macosx/velocity-compress.dylib"), "native (macOS)",
                             NativeVelocityCompressor.FACTORY),
                     new NativeCodeLoader.Variant<>(NativeCodeLoader.LINUX,
-                            copyAndLoadNative("/linux_x64/velocity-compress.so"), "native compression (Linux amd64)",
+                            copyAndLoadNative("/linux_x64/velocity-compress.so"), "native (Linux amd64)",
                             NativeVelocityCompressor.FACTORY),
-                    new NativeCodeLoader.Variant<>(NativeCodeLoader.ALWAYS, () -> {}, "Java compression", JavaVelocityCompressor.FACTORY)
+                    new NativeCodeLoader.Variant<>(NativeCodeLoader.ALWAYS, () -> {}, "Java", JavaVelocityCompressor.FACTORY)
             )
     );
 

proxy/build.gradle

@@ -1,6 +1,7 @@
 plugins {
     id 'java'
     id 'com.github.johnrengelman.shadow' version '2.0.4'
+    id 'de.sebastianboegl.shadow.transformer.log4j' version '2.1.1'
 }
 
 compileJava {
@@ -21,17 +22,70 @@ jar {
 dependencies {
     compile project(':velocity-api')
     compile project(':velocity-native')
+
     compile "io.netty:netty-codec:${nettyVersion}"
     compile "io.netty:netty-codec-http:${nettyVersion}"
     compile "io.netty:netty-handler:${nettyVersion}"
     compile "io.netty:netty-transport-native-epoll:${nettyVersion}"
     compile "io.netty:netty-transport-native-epoll:${nettyVersion}:linux-x86_64"
+    compile "io.netty:netty-transport-native-kqueue:${nettyVersion}:osx-x86_64"
+
     compile "org.apache.logging.log4j:log4j-api:${log4jVersion}"
     compile "org.apache.logging.log4j:log4j-core:${log4jVersion}"
+    compile "org.apache.logging.log4j:log4j-slf4j-impl:${log4jVersion}"
+
+    compile 'net.minecrell:terminalconsoleappender:1.1.1'
+    runtime 'net.java.dev.jna:jna:4.5.2' // Needed for JLine
+    runtime 'com.lmax:disruptor:3.4.2' // Async loggers
+
+    compile 'it.unimi.dsi:fastutil:8.2.1'
+    compile 'net.kyori:event-method-asm:3.0.0'
+
     testCompile "org.junit.jupiter:junit-jupiter-api:${junitVersion}"
     testCompile "org.junit.jupiter:junit-jupiter-engine:${junitVersion}"
 }
 
+shadowJar {
+    exclude 'it/unimi/dsi/fastutil/booleans/**'
+    exclude 'it/unimi/dsi/fastutil/bytes/**'
+    exclude 'it/unimi/dsi/fastutil/chars/**'
+    exclude 'it/unimi/dsi/fastutil/doubles/**'
+    exclude 'it/unimi/dsi/fastutil/floats/**'
+    exclude 'it/unimi/dsi/fastutil/ints/*Int2*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntAVL*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntArray*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntBi*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntList*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntOpen*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntRB*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntSet*'
+    exclude 'it/unimi/dsi/fastutil/ints/IntSorted*'
+    exclude 'it/unimi/dsi/fastutil/io/**'
+    exclude 'it/unimi/dsi/fastutil/longs/**'
+    exclude 'it/unimi/dsi/fastutil/objects/*ObjectArray*'
+    exclude 'it/unimi/dsi/fastutil/objects/*ObjectAVL*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object*Big*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Boolean*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Byte*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Char*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Double*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Float*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2IntArray*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2IntAVL*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2IntLinked*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object*OpenCustom*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2IntRB*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2IntSorted*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Long*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Object*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Reference*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Object2Short*'
+    exclude 'it/unimi/dsi/fastutil/objects/*ObjectRB*'
+    exclude 'it/unimi/dsi/fastutil/objects/*ObjectSorted*'
+    exclude 'it/unimi/dsi/fastutil/objects/*Reference*'
+    exclude 'it/unimi/dsi/fastutil/shorts/**'
+}
+
 artifacts {
     archives shadowJar
 }

proxy/src/main/java/com/velocitypowered/proxy/Velocity.java

@@ -1,12 +1,33 @@
 package com.velocitypowered.proxy;
 
+import com.velocitypowered.proxy.console.VelocityConsole;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import java.text.DecimalFormat;
+
 public class Velocity {
-    public static void main(String... args) throws InterruptedException {
+    private static final Logger logger = LogManager.getLogger(Velocity.class);
+
+    private static long startTime;
+
+    static {
+        // We use BufferedImage for favicons, and on macOS this puts the Java application in the dock. How inconvenient.
+        // Force AWT to work with its head chopped off.
+        System.setProperty("java.awt.headless", "true");
+    }
+
+    public static void main(String... args) {
+        startTime = System.currentTimeMillis();
+        logger.info("Booting up Velocity...");
+
         final VelocityServer server = VelocityServer.getServer();
         server.start();
 
         Runtime.getRuntime().addShutdownHook(new Thread(server::shutdown, "Shutdown thread"));
 
-        Thread.currentThread().join();
+        double bootTime = (System.currentTimeMillis() - startTime) / 1000d;
+        logger.info("Done ({}s)!", new DecimalFormat("#.##").format(bootTime));
+        new VelocityConsole(server).start();
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -1,17 +1,40 @@
 package com.velocitypowered.proxy;
 
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
-import com.velocitypowered.natives.util.Natives;
-import com.velocitypowered.network.ConnectionManager;
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.api.event.EventManager;
+import com.velocitypowered.api.event.proxy.ProxyInitializeEvent;
+import com.velocitypowered.api.event.proxy.ProxyShutdownEvent;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.ProxyServer;
+import com.velocitypowered.api.util.Favicon;
+import com.velocitypowered.api.plugin.PluginManager;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+import com.velocitypowered.proxy.network.ConnectionManager;
+import com.velocitypowered.proxy.command.ServerCommand;
+import com.velocitypowered.proxy.command.ShutdownCommand;
+import com.velocitypowered.proxy.command.VelocityCommand;
 import com.velocitypowered.proxy.config.VelocityConfiguration;
+import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.connection.http.NettyHttpClient;
-import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.proxy.command.VelocityCommandManager;
+import com.velocitypowered.proxy.messages.VelocityChannelRegistrar;
+import com.velocitypowered.proxy.plugin.VelocityEventManager;
+import com.velocitypowered.proxy.protocol.util.FaviconSerializer;
+import com.velocitypowered.proxy.plugin.VelocityPluginManager;
+import com.velocitypowered.proxy.scheduler.Sleeper;
+import com.velocitypowered.proxy.scheduler.VelocityScheduler;
 import com.velocitypowered.proxy.util.AddressUtil;
 import com.velocitypowered.proxy.util.EncryptionUtils;
+import com.velocitypowered.proxy.util.Ratelimiter;
 import com.velocitypowered.proxy.util.ServerMap;
 import io.netty.bootstrap.Bootstrap;
 import net.kyori.text.Component;
+import net.kyori.text.TextComponent;
+import net.kyori.text.serializer.ComponentSerializers;
 import net.kyori.text.serializer.GsonComponentSerializer;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -22,13 +45,17 @@ import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.security.KeyPair;
-import java.util.Map;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.atomic.AtomicBoolean;
 
-public class VelocityServer {
+public class VelocityServer implements ProxyServer {
     private static final Logger logger = LogManager.getLogger(VelocityServer.class);
     private static final VelocityServer INSTANCE = new VelocityServer();
     public static final Gson GSON = new GsonBuilder()
             .registerTypeHierarchyAdapter(Component.class, new GsonComponentSerializer())
+            .registerTypeHierarchyAdapter(Favicon.class, new FaviconSerializer())
             .create();
 
     private final ConnectionManager cm = new ConnectionManager();
@@ -36,8 +63,33 @@ public class VelocityServer {
     private NettyHttpClient httpClient;
     private KeyPair serverKeyPair;
     private final ServerMap servers = new ServerMap();
+    private final VelocityCommandManager commandManager = new VelocityCommandManager();
+    private final AtomicBoolean shutdownInProgress = new AtomicBoolean(false);
+    private boolean shutdown = false;
+    private final VelocityPluginManager pluginManager = new VelocityPluginManager(this);
+
+    private final Map<UUID, ConnectedPlayer> connectionsByUuid = new ConcurrentHashMap<>();
+    private final Map<String, ConnectedPlayer> connectionsByName = new ConcurrentHashMap<>();
+    private final CommandSource consoleCommandSource = new CommandSource() {
+        @Override
+        public void sendMessage(Component component) {
+            logger.info(ComponentSerializers.LEGACY.serialize(component));
+        }
+
+        @Override
+        public boolean hasPermission(String permission) {
+            return true;
+        }
+    };
+    private Ratelimiter ipAttemptLimiter;
+    private VelocityEventManager eventManager;
+    private VelocityScheduler scheduler;
+    private VelocityChannelRegistrar channelRegistrar;
 
     private VelocityServer() {
+        commandManager.register(new VelocityCommand(), "velocity");
+        commandManager.register(new ServerCommand(), "server");
+        commandManager.register(new ShutdownCommand(), "shutdown");
     }
 
     public static VelocityServer getServer() {
@@ -52,12 +104,12 @@ public class VelocityServer {
         return configuration;
     }
 
-    public void start() {
-        logger.info("Using {}", Natives.compressor.getLoadedVariant());
-        logger.info("Using {}", Natives.cipher.getLoadedVariant());
+    @Override
+    public VelocityCommandManager getCommandManager() {
+        return commandManager;
+    }
 
-        // Create a key pair
-        logger.info("Booting up Velocity...");
+    public void start() {
         try {
             Path configPath = Paths.get("velocity.toml");
             try {
@@ -82,10 +134,55 @@ public class VelocityServer {
         }
 
         serverKeyPair = EncryptionUtils.createRsaKeyPair(1024);
-
+        ipAttemptLimiter = new Ratelimiter(configuration.getLoginRatelimit());
         httpClient = new NettyHttpClient(this);
+        eventManager = new VelocityEventManager(pluginManager);
+        scheduler = new VelocityScheduler(pluginManager, Sleeper.SYSTEM);
+        channelRegistrar = new VelocityChannelRegistrar();
+        loadPlugins();
+
+        try {
+            // Go ahead and fire the proxy initialization event. We block since plugins should have a chance
+            // to fully initialize before we accept any connections to the server.
+            eventManager.fire(new ProxyInitializeEvent()).get();
+        } catch (InterruptedException | ExecutionException e) {
+            // Ignore, we don't care. InterruptedException is unlikely to happen (and if it does, you've got bigger
+            // issues) and there is almost no chance ExecutionException will be thrown.
+        }
 
         this.cm.bind(configuration.getBind());
+
+        if (configuration.isQueryEnabled()) {
+            this.cm.queryBind(configuration.getBind().getHostString(), configuration.getQueryPort());
+        }
+    }
+
+    private void loadPlugins() {
+        logger.info("Loading plugins...");
+
+        try {
+            Path pluginPath = Paths.get("plugins");
+
+            if (Files.notExists(pluginPath)) {
+                Files.createDirectory(pluginPath);
+            } else {
+                if (!Files.isDirectory(pluginPath)) {
+                    logger.warn("Plugin location {} is not a directory, continuing without loading plugins", pluginPath);
+                    return;
+                }
+
+                pluginManager.loadPlugins(pluginPath);
+            }
+        } catch (Exception e) {
+            logger.error("Couldn't load plugins", e);
+        }
+
+        // Register the plugin main classes so that we may proceed with firing the proxy initialize event
+        pluginManager.getPlugins().forEach(container -> {
+            container.getInstance().ifPresent(plugin -> eventManager.register(plugin, plugin));
+        });
+
+        logger.info("Loaded {} plugins", pluginManager.getPlugins().size());
     }
 
     public ServerMap getServers() {
@@ -96,11 +193,122 @@ public class VelocityServer {
         return this.cm.createWorker();
     }
 
+    public boolean isShutdown() {
+        return shutdown;
+    }
+
     public void shutdown() {
+        if (!shutdownInProgress.compareAndSet(false, true)) return;
+        logger.info("Shutting down the proxy...");
+
+        for (ConnectedPlayer player : ImmutableList.copyOf(connectionsByUuid.values())) {
+            player.close(TextComponent.of("Proxy shutting down."));
+        }
+
         this.cm.shutdown();
+
+        eventManager.fire(new ProxyShutdownEvent());
+        try {
+            if (!eventManager.shutdown() || !scheduler.shutdown()) {
+                logger.error("Your plugins took over 10 seconds to shut down.");
+            }
+        } catch (InterruptedException e) {
+            // Not much we can do about this...
+        }
+
+        shutdown = true;
     }
 
     public NettyHttpClient getHttpClient() {
         return httpClient;
     }
+
+    public Ratelimiter getIpAttemptLimiter() {
+        return ipAttemptLimiter;
+    }
+
+    public boolean registerConnection(ConnectedPlayer connection) {
+        String lowerName = connection.getUsername().toLowerCase(Locale.US);
+        if (connectionsByName.putIfAbsent(lowerName, connection) != null) {
+            return false;
+        }
+        if (connectionsByUuid.putIfAbsent(connection.getUniqueId(), connection) != null) {
+            connectionsByName.remove(lowerName, connection);
+            return false;
+        }
+        return true;
+    }
+
+    public void unregisterConnection(ConnectedPlayer connection) {
+        connectionsByName.remove(connection.getUsername().toLowerCase(Locale.US), connection);
+        connectionsByUuid.remove(connection.getUniqueId(), connection);
+    }
+
+    @Override
+    public Optional<Player> getPlayer(String username) {
+        Preconditions.checkNotNull(username, "username");
+        return Optional.ofNullable(connectionsByName.get(username.toLowerCase(Locale.US)));
+    }
+
+    @Override
+    public Optional<Player> getPlayer(UUID uuid) {
+        Preconditions.checkNotNull(uuid, "uuid");
+        return Optional.ofNullable(connectionsByUuid.get(uuid));
+    }
+
+    @Override
+    public Collection<Player> getAllPlayers() {
+        return ImmutableList.copyOf(connectionsByUuid.values());
+    }
+
+    @Override
+    public int getPlayerCount() {
+        return connectionsByUuid.size();
+    }
+
+    @Override
+    public Optional<ServerInfo> getServerInfo(String name) {
+        Preconditions.checkNotNull(name, "name");
+        return servers.getServer(name);
+    }
+
+    @Override
+    public Collection<ServerInfo> getAllServers() {
+        return servers.getAllServers();
+    }
+
+    @Override
+    public void registerServer(ServerInfo server) {
+        servers.register(server);
+    }
+
+    @Override
+    public void unregisterServer(ServerInfo server) {
+        servers.unregister(server);
+    }
+
+    @Override
+    public CommandSource getConsoleCommandSource() {
+        return consoleCommandSource;
+    }
+
+    @Override
+    public PluginManager getPluginManager() {
+        return pluginManager;
+    }
+
+    @Override
+    public EventManager getEventManager() {
+        return eventManager;
+    }
+
+    @Override
+    public VelocityScheduler getScheduler() {
+        return scheduler;
+    }
+
+    @Override
+    public VelocityChannelRegistrar getChannelRegistrar() {
+        return channelRegistrar;
+    }
 }

proxy/src/main/java/com/velocitypowered/proxy/command/ServerCommand.java

@@ -0,0 +1,58 @@
+package com.velocitypowered.proxy.command;
+
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.command.Command;
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+import com.velocitypowered.proxy.VelocityServer;
+import net.kyori.text.TextComponent;
+import net.kyori.text.format.TextColor;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+public class ServerCommand implements Command {
+    @Override
+    public void execute(CommandSource source, String[] args) {
+        if (!(source instanceof Player)) {
+            source.sendMessage(TextComponent.of("Only players may run this command.", TextColor.RED));
+            return;
+        }
+
+        Player player = (Player) source;
+        if (args.length == 1) {
+            // Trying to connect to a server.
+            String serverName = args[0];
+            Optional<ServerInfo> server = VelocityServer.getServer().getServerInfo(serverName);
+            if (!server.isPresent()) {
+                player.sendMessage(TextComponent.of("Server " + serverName + " doesn't exist.", TextColor.RED));
+                return;
+            }
+
+            player.createConnectionRequest(server.get()).fireAndForget();
+        } else {
+            String serverList = VelocityServer.getServer().getAllServers().stream()
+                    .map(ServerInfo::getName)
+                    .collect(Collectors.joining(", "));
+            player.sendMessage(TextComponent.of("Available servers: " + serverList, TextColor.YELLOW));
+        }
+    }
+
+    @Override
+    public List<String> suggest(CommandSource source, String[] currentArgs) {
+        if (currentArgs.length == 0) {
+            return VelocityServer.getServer().getAllServers().stream()
+                    .map(ServerInfo::getName)
+                    .collect(Collectors.toList());
+        } else if (currentArgs.length == 1) {
+            return VelocityServer.getServer().getAllServers().stream()
+                    .map(ServerInfo::getName)
+                    .filter(name -> name.regionMatches(true, 0, currentArgs[0], 0, currentArgs[0].length()))
+                    .collect(Collectors.toList());
+        } else {
+            return ImmutableList.of();
+        }
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/command/ShutdownCommand.java

@@ -0,0 +1,18 @@
+package com.velocitypowered.proxy.command;
+
+import com.velocitypowered.api.command.Command;
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.proxy.VelocityServer;
+import net.kyori.text.TextComponent;
+import net.kyori.text.format.TextColor;
+
+public class ShutdownCommand implements Command {
+    @Override
+    public void execute(CommandSource source, String[] args) {
+        if (source != VelocityServer.getServer().getConsoleCommandSource()) {
+            source.sendMessage(TextComponent.of("You are not allowed to use this command.", TextColor.RED));
+            return;
+        }
+        VelocityServer.getServer().shutdown();
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/command/VelocityCommand.java

@@ -0,0 +1,40 @@
+package com.velocitypowered.proxy.command;
+
+import com.velocitypowered.api.command.Command;
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.proxy.VelocityServer;
+import net.kyori.text.TextComponent;
+import net.kyori.text.event.ClickEvent;
+import net.kyori.text.format.TextColor;
+
+public class VelocityCommand implements Command {
+    @Override
+    public void execute(CommandSource source, String[] args) {
+        String implVersion = VelocityServer.class.getPackage().getImplementationVersion();
+        TextComponent thisIsVelocity = TextComponent.builder()
+                .content("This is ")
+                .append(TextComponent.of("Velocity " + implVersion, TextColor.DARK_AQUA))
+                .append(TextComponent.of(", the next generation Minecraft: Java Edition proxy.").resetStyle())
+                .build();
+        TextComponent velocityInfo = TextComponent.builder()
+                .content("Copyright 2018 Velocity Contributors. Velocity is freely licensed under the terms of the " +
+                        "MIT License.")
+                .build();
+        TextComponent velocityWebsite = TextComponent.builder()
+                .content("Visit the ")
+                .append(TextComponent.builder("Velocity website")
+                        .color(TextColor.GREEN)
+                        .clickEvent(new ClickEvent(ClickEvent.Action.OPEN_URL, "https://www.velocitypowered.com"))
+                        .build())
+                .append(TextComponent.of(" or the ").resetStyle())
+                .append(TextComponent.builder("Velocity GitHub")
+                        .color(TextColor.GREEN)
+                        .clickEvent(new ClickEvent(ClickEvent.Action.OPEN_URL, "https://github.com/astei/velocity"))
+                        .build())
+                .build();
+
+        source.sendMessage(thisIsVelocity);
+        source.sendMessage(velocityInfo);
+        source.sendMessage(velocityWebsite);
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/command/VelocityCommandManager.java

@@ -0,0 +1,85 @@
+package com.velocitypowered.proxy.command;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.command.Command;
+import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.api.command.CommandManager;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class VelocityCommandManager implements CommandManager {
+    private final Map<String, Command> commands = new HashMap<>();
+
+    @Override
+    public void register(final Command command, final String... aliases) {
+        Preconditions.checkNotNull(aliases, "aliases");
+        Preconditions.checkNotNull(command, "executor");
+        for (int i = 0, length = aliases.length; i < length; i++) {
+            final String alias = aliases[i];
+            Preconditions.checkNotNull(aliases, "alias at index %s", i);
+            this.commands.put(alias.toLowerCase(Locale.ENGLISH), command);
+        }
+    }
+
+    @Override
+    public void unregister(final String alias) {
+        Preconditions.checkNotNull(alias, "name");
+        this.commands.remove(alias.toLowerCase(Locale.ENGLISH));
+    }
+
+    @Override
+    public boolean execute(CommandSource source, String cmdLine) {
+        Preconditions.checkNotNull(source, "invoker");
+        Preconditions.checkNotNull(cmdLine, "cmdLine");
+
+        String[] split = cmdLine.split(" ", -1);
+        if (split.length == 0) {
+            return false;
+        }
+
+        String alias = split[0];
+        String[] actualArgs = Arrays.copyOfRange(split, 1, split.length);
+        Command command = commands.get(alias.toLowerCase(Locale.ENGLISH));
+        if (command == null) {
+            return false;
+        }
+
+        try {
+            command.execute(source, actualArgs);
+            return true;
+        } catch (Exception e) {
+            throw new RuntimeException("Unable to invoke command " + cmdLine + " for " + source, e);
+        }
+    }
+
+    public Optional<List<String>> offerSuggestions(CommandSource source, String cmdLine) {
+        Preconditions.checkNotNull(source, "source");
+        Preconditions.checkNotNull(cmdLine, "cmdLine");
+
+        String[] split = cmdLine.split(" ", -1);
+        if (split.length == 0) {
+            return Optional.empty();
+        }
+
+        String command = split[0];
+        if (split.length == 1) {
+            return Optional.of(commands.keySet().stream()
+                    .filter(cmd -> cmd.regionMatches(true, 0, command, 0, command.length()))
+                    .collect(Collectors.toList()));
+        }
+
+        String[] actualArgs = Arrays.copyOfRange(split, 1, split.length);
+        Command executor = commands.get(command);
+        if (executor == null) {
+            return Optional.empty();
+        }
+
+        try {
+            return Optional.of(executor.suggest(source, actualArgs));
+        } catch (Exception e) {
+            throw new RuntimeException("Unable to invoke suggestions for command " + command + " for " + source, e);
+        }
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/config/PlayerInfoForwarding.java

@@ -1,6 +1,6 @@
 package com.velocitypowered.proxy.config;
 
-public enum IPForwardingMode {
+public enum PlayerInfoForwarding {
     NONE,
     LEGACY,
     MODERN

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -2,8 +2,10 @@ package com.velocitypowered.proxy.config;
 
 import com.google.common.collect.ImmutableMap;
 import com.moandjiezana.toml.Toml;
+import com.velocitypowered.api.util.Favicon;
 import com.velocitypowered.proxy.util.AddressUtil;
 import com.velocitypowered.api.util.LegacyChatColorUtils;
+import io.netty.buffer.ByteBufUtil;
 import net.kyori.text.Component;
 import net.kyori.text.serializer.ComponentSerializers;
 import org.apache.logging.log4j.LogManager;
@@ -15,6 +17,7 @@ import java.net.InetSocketAddress;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -26,27 +29,39 @@ public class VelocityConfiguration {
     private final String motd;
     private final int showMaxPlayers;
     private final boolean onlineMode;
-    private final IPForwardingMode ipForwardingMode;
+    private final PlayerInfoForwarding playerInfoForwardingMode;
     private final Map<String, String> servers;
     private final List<String> attemptConnectionOrder;
     private final int compressionThreshold;
     private final int compressionLevel;
+    private final int loginRatelimit;
+
+    private final boolean queryEnabled;
+    private final int queryPort;
 
     private Component motdAsComponent;
+    private Favicon favicon;
+
+    private final byte[] forwardingSecret;
 
     private VelocityConfiguration(String bind, String motd, int showMaxPlayers, boolean onlineMode,
-                                  IPForwardingMode ipForwardingMode, Map<String, String> servers,
+                                  PlayerInfoForwarding playerInfoForwardingMode, Map<String, String> servers,
                                   List<String> attemptConnectionOrder, int compressionThreshold,
-                                  int compressionLevel) {
+                                  int compressionLevel, int loginRatelimit, boolean queryEnabled,
+                                  int queryPort, byte[] forwardingSecret) {
         this.bind = bind;
         this.motd = motd;
         this.showMaxPlayers = showMaxPlayers;
         this.onlineMode = onlineMode;
-        this.ipForwardingMode = ipForwardingMode;
+        this.playerInfoForwardingMode = playerInfoForwardingMode;
         this.servers = servers;
         this.attemptConnectionOrder = attemptConnectionOrder;
         this.compressionThreshold = compressionThreshold;
         this.compressionLevel = compressionLevel;
+        this.loginRatelimit = loginRatelimit;
+        this.queryEnabled = queryEnabled;
+        this.queryPort = queryPort;
+        this.forwardingSecret = forwardingSecret;
     }
 
     public boolean validate() {
@@ -68,9 +83,15 @@ public class VelocityConfiguration {
             logger.info("Proxy is running in offline mode!");
         }
 
-        switch (ipForwardingMode) {
+        switch (playerInfoForwardingMode) {
             case NONE:
-                logger.info("IP forwarding is disabled! All players will appear to be connecting from the proxy and will have offline-mode UUIDs.");
+                logger.info("Player info forwarding is disabled! All players will appear to be connecting from the proxy and will have offline-mode UUIDs.");
+                break;
+            case MODERN:
+                if (forwardingSecret.length == 0) {
+                    logger.error("You don't have a forwarding secret set.");
+                    valid = false;
+                }
                 break;
         }
 
@@ -109,23 +130,51 @@ public class VelocityConfiguration {
 
         if (compressionLevel < -1 || compressionLevel > 9) {
             logger.error("Invalid compression level {}", compressionLevel);
+            valid = false;
         } else if (compressionLevel == 0) {
             logger.warn("ALL packets going through the proxy are going to be uncompressed. This will increase bandwidth usage.");
         }
 
         if (compressionThreshold < -1) {
             logger.error("Invalid compression threshold {}", compressionLevel);
+            valid = false;
         } else if (compressionThreshold == 0) {
             logger.warn("ALL packets going through the proxy are going to be compressed. This may hurt performance.");
         }
 
+        if (loginRatelimit < 0) {
+            logger.error("Invalid login ratelimit {}", loginRatelimit);
+            valid = false;
+        }
+
+        loadFavicon();
+
         return valid;
     }
 
+    private void loadFavicon() {
+        Path faviconPath = Paths.get("server-icon.png");
+        if (Files.exists(faviconPath)) {
+            try {
+                this.favicon = Favicon.create(faviconPath);
+            } catch (Exception e) {
+                logger.info("Unable to load your server-icon.png, continuing without it.", e);
+            }
+        }
+    }
+
     public InetSocketAddress getBind() {
         return AddressUtil.parseAddress(bind);
     }
 
+    public boolean isQueryEnabled() {
+        return queryEnabled;
+    }
+
+    public int getQueryPort() {
+        return queryPort;
+    }
+
     public String getMotd() {
         return motd;
     }
@@ -149,8 +198,8 @@ public class VelocityConfiguration {
         return onlineMode;
     }
 
-    public IPForwardingMode getIpForwardingMode() {
-        return ipForwardingMode;
+    public PlayerInfoForwarding getPlayerInfoForwardingMode() {
+        return playerInfoForwardingMode;
     }
 
     public Map<String, String> getServers() {
@@ -169,6 +218,18 @@ public class VelocityConfiguration {
         return compressionLevel;
     }
 
+    public int getLoginRatelimit() {
+        return loginRatelimit;
+    }
+
+    public Favicon getFavicon() {
+        return favicon;
+    }
+
+    public byte[] getForwardingSecret() {
+        return forwardingSecret;
+    }
+
     @Override
     public String toString() {
         return "VelocityConfiguration{" +
@@ -176,12 +237,17 @@ public class VelocityConfiguration {
                 ", motd='" + motd + '\'' +
                 ", showMaxPlayers=" + showMaxPlayers +
                 ", onlineMode=" + onlineMode +
-                ", ipForwardingMode=" + ipForwardingMode +
+                ", playerInfoForwardingMode=" + playerInfoForwardingMode +
                 ", servers=" + servers +
                 ", attemptConnectionOrder=" + attemptConnectionOrder +
                 ", compressionThreshold=" + compressionThreshold +
                 ", compressionLevel=" + compressionLevel +
+                ", loginRatelimit=" + loginRatelimit +
+                ", queryEnabled=" + queryEnabled +
+                ", queryPort=" + queryPort +
                 ", motdAsComponent=" + motdAsComponent +
+                ", favicon=" + favicon +
+                ", forwardingSecret=" + ByteBufUtil.hexDump(forwardingSecret) +
                 '}';
     }
 
@@ -200,16 +266,23 @@ public class VelocityConfiguration {
                 }
             }
 
+            byte[] forwardingSecret = toml.getString("player-info-forwarding-secret", "5up3r53cr3t")
+                    .getBytes(StandardCharsets.UTF_8);
+
             return new VelocityConfiguration(
-                    toml.getString("bind"),
-                    toml.getString("motd"),
-                    toml.getLong("show-max-players").intValue(),
-                    toml.getBoolean("online-mode"),
-                    IPForwardingMode.valueOf(toml.getString("ip-forwarding").toUpperCase()),
+                    toml.getString("bind", "0.0.0.0:25577"),
+                    toml.getString("motd", "&3A Velocity Server"),
+                    toml.getLong("show-max-players", 500L).intValue(),
+                    toml.getBoolean("online-mode", true),
+                    PlayerInfoForwarding.valueOf(toml.getString("player-info-forwarding", "MODERN").toUpperCase()),
                     ImmutableMap.copyOf(servers),
                     toml.getTable("servers").getList("try"),
                     toml.getTable("advanced").getLong("compression-threshold", 1024L).intValue(),
-                    toml.getTable("advanced").getLong("compression-level", -1L).intValue());
+                    toml.getTable("advanced").getLong("compression-level", -1L).intValue(),
+                    toml.getTable("advanced").getLong("login-ratelimit", 3000L).intValue(),
+                    toml.getTable("query").getBoolean("enabled", false),
+                    toml.getTable("query").getLong("port", 25577L).intValue(),
+                    forwardingSecret);
         }
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftConnection.java

@@ -5,11 +5,12 @@ import com.velocitypowered.natives.compression.VelocityCompressor;
 import com.velocitypowered.natives.encryption.VelocityCipherFactory;
 import com.velocitypowered.natives.util.Natives;
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.proxy.protocol.PacketWrapper;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
-import com.velocitypowered.natives.encryption.JavaVelocityCipher;
 import com.velocitypowered.natives.encryption.VelocityCipher;
 import com.velocitypowered.proxy.protocol.netty.*;
+import io.netty.buffer.ByteBuf;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFutureListener;
 import io.netty.channel.ChannelHandlerContext;
@@ -23,14 +24,14 @@ import javax.crypto.spec.SecretKeySpec;
 
 import java.security.GeneralSecurityException;
 
-import static com.velocitypowered.network.Connections.CIPHER_DECODER;
-import static com.velocitypowered.network.Connections.CIPHER_ENCODER;
-import static com.velocitypowered.network.Connections.COMPRESSION_DECODER;
-import static com.velocitypowered.network.Connections.COMPRESSION_ENCODER;
-import static com.velocitypowered.network.Connections.FRAME_DECODER;
-import static com.velocitypowered.network.Connections.FRAME_ENCODER;
-import static com.velocitypowered.network.Connections.MINECRAFT_DECODER;
-import static com.velocitypowered.network.Connections.MINECRAFT_ENCODER;
+import static com.velocitypowered.proxy.network.Connections.CIPHER_DECODER;
+import static com.velocitypowered.proxy.network.Connections.CIPHER_ENCODER;
+import static com.velocitypowered.proxy.network.Connections.COMPRESSION_DECODER;
+import static com.velocitypowered.proxy.network.Connections.COMPRESSION_ENCODER;
+import static com.velocitypowered.proxy.network.Connections.FRAME_DECODER;
+import static com.velocitypowered.proxy.network.Connections.FRAME_ENCODER;
+import static com.velocitypowered.proxy.network.Connections.MINECRAFT_DECODER;
+import static com.velocitypowered.proxy.network.Connections.MINECRAFT_ENCODER;
 
 /**
  * A utility class to make working with the pipeline a little less painful and transparently handles certain Minecraft
@@ -40,7 +41,6 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     private static final Logger logger = LogManager.getLogger(MinecraftConnection.class);
 
     private final Channel channel;
-    private boolean closed;
     private StateRegistry state;
     private MinecraftSessionHandler sessionHandler;
     private int protocolVersion;
@@ -48,7 +48,6 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
 
     public MinecraftConnection(Channel channel) {
         this.channel = channel;
-        this.closed = false;
         this.state = StateRegistry.HANDSHAKE;
     }
 
@@ -72,24 +71,17 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
         if (association != null) {
             logger.info("{} has disconnected", association);
         }
-
-        teardown();
     }
 
     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
-        if (msg instanceof PacketWrapper) {
-            PacketWrapper pw = (PacketWrapper) msg;
+        if (msg instanceof MinecraftPacket) {
+            sessionHandler.handle((MinecraftPacket) msg);
+        } else if (msg instanceof ByteBuf) {
             try {
-                if (sessionHandler != null) {
-                    if (pw.getPacket() == null) {
-                        sessionHandler.handleUnknown(pw.getBuffer());
-                    } else {
-                        sessionHandler.handle(pw.getPacket());
-                    }
-                }
+                sessionHandler.handleUnknown((ByteBuf) msg);
             } finally {
-                ReferenceCountUtil.release(pw.getBuffer());
+                ReferenceCountUtil.release(msg);
             }
         }
     }
@@ -107,40 +99,38 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
                 logger.error("{} encountered an exception", ctx.channel().remoteAddress(), cause);
             }
 
-            closed = true;
             ctx.close();
         }
     }
 
     public void write(Object msg) {
-        ensureOpen();
-        channel.writeAndFlush(msg, channel.voidPromise());
+        if (channel.isActive()) {
+            channel.writeAndFlush(msg, channel.voidPromise());
+        }
     }
 
     public void delayedWrite(Object msg) {
-        ensureOpen();
-        channel.write(msg, channel.voidPromise());
+        if (channel.isActive()) {
+            channel.write(msg, channel.voidPromise());
+        }
     }
 
     public void flush() {
-        ensureOpen();
-        channel.flush();
+        if (channel.isActive()) {
+            channel.flush();
+        }
     }
 
     public void closeWith(Object msg) {
-        ensureOpen();
-        teardown();
-        channel.writeAndFlush(msg).addListener(ChannelFutureListener.CLOSE);
+        if (channel.isActive()) {
+            channel.writeAndFlush(msg).addListener(ChannelFutureListener.CLOSE);
+        }
     }
 
     public void close() {
-        ensureOpen();
-        teardown();
-        channel.close();
-    }
-
-    public void teardown() {
-        closed = true;
+        if (channel.isActive()) {
+            channel.close();
+        }
     }
 
     public Channel getChannel() {
@@ -148,7 +138,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     }
 
     public boolean isClosed() {
-        return closed;
+        return !channel.isActive();
     }
 
     public StateRegistry getState() {
@@ -167,8 +157,14 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
 
     public void setProtocolVersion(int protocolVersion) {
         this.protocolVersion = protocolVersion;
-        this.channel.pipeline().get(MinecraftEncoder.class).setProtocolVersion(protocolVersion);
-        this.channel.pipeline().get(MinecraftDecoder.class).setProtocolVersion(protocolVersion);
+        if (protocolVersion != ProtocolConstants.LEGACY) {
+            this.channel.pipeline().get(MinecraftEncoder.class).setProtocolVersion(protocolVersion);
+            this.channel.pipeline().get(MinecraftDecoder.class).setProtocolVersion(protocolVersion);
+        } else {
+            // Legacy handshake handling
+            this.channel.pipeline().remove(MINECRAFT_ENCODER);
+            this.channel.pipeline().remove(MINECRAFT_DECODER);
+        }
     }
 
     public MinecraftSessionHandler getSessionHandler() {
@@ -184,10 +180,12 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     }
 
     private void ensureOpen() {
-        Preconditions.checkState(!closed, "Connection is closed.");
+        Preconditions.checkState(!isClosed(), "Connection is closed.");
     }
 
     public void setCompressionThreshold(int threshold) {
+        ensureOpen();
+
         if (threshold == -1) {
             channel.pipeline().remove(COMPRESSION_DECODER);
             channel.pipeline().remove(COMPRESSION_ENCODER);
@@ -204,6 +202,8 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     }
 
     public void enableEncryption(byte[] secret) throws GeneralSecurityException {
+        ensureOpen();
+
         SecretKey key = new SecretKeySpec(secret, "AES");
 
         VelocityCipherFactory factory = Natives.cipher.get();

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftSessionHandler.java

@@ -4,7 +4,7 @@ import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import io.netty.buffer.ByteBuf;
 
 public interface MinecraftSessionHandler {
-    void handle(MinecraftPacket packet) throws Exception;
+    void handle(MinecraftPacket packet);
 
     default void handleUnknown(ByteBuf buf) {
         // No-op: we'll release the buffer later.

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -1,5 +1,9 @@
 package com.velocitypowered.proxy.connection.backend;
 
+import com.velocitypowered.api.event.player.ServerConnectedEvent;
+import com.velocitypowered.api.proxy.messages.ChannelSide;
+import com.velocitypowered.api.proxy.messages.MessageHandler;
+import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
@@ -7,31 +11,40 @@ import com.velocitypowered.proxy.protocol.packet.*;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import io.netty.buffer.ByteBuf;
-import io.netty.util.ReferenceCountUtil;
 
 public class BackendPlaySessionHandler implements MinecraftSessionHandler {
-    private final ServerConnection connection;
+    private final VelocityServerConnection connection;
 
-    public BackendPlaySessionHandler(ServerConnection connection) {
+    public BackendPlaySessionHandler(VelocityServerConnection connection) {
         this.connection = connection;
     }
 
+    @Override
+    public void activated() {
+        VelocityServer.getServer().getEventManager().fireAndForget(new ServerConnectedEvent(connection.getPlayer(),
+                connection.getServerInfo()));
+    }
+
     @Override
     public void handle(MinecraftPacket packet) {
+        if (!connection.getPlayer().isActive()) {
+            // Connection was left open accidentally. Close it so as to avoid "You logged in from another location"
+            // errors.
+            connection.getMinecraftConnection().close();
+            return;
+        }
+
         ClientPlaySessionHandler playerHandler =
-                (ClientPlaySessionHandler) connection.getProxyPlayer().getConnection().getSessionHandler();
+                (ClientPlaySessionHandler) connection.getPlayer().getConnection().getSessionHandler();
         if (packet instanceof KeepAlive) {
-            // Forward onto the server
-            connection.getMinecraftConnection().write(packet);
+            // Forward onto the player
+            playerHandler.setLastPing(((KeepAlive) packet).getRandomId());
+            connection.getPlayer().getConnection().write(packet);
         } else if (packet instanceof Disconnect) {
             Disconnect original = (Disconnect) packet;
-            connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(), original);
+            connection.getPlayer().handleConnectionException(connection.getServerInfo(), original);
         } else if (packet instanceof JoinGame) {
             playerHandler.handleBackendJoinGame((JoinGame) packet);
-        } else if (packet instanceof Respawn) {
-            // Record the dimension switch, and then forward the packet on.
-            playerHandler.setCurrentDimension(((Respawn) packet).getDimension());
-            connection.getProxyPlayer().getConnection().write(packet);
         } else if (packet instanceof BossBar) {
             BossBar bossBar = (BossBar) packet;
             switch (bossBar.getAction()) {
@@ -42,7 +55,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
                     playerHandler.getServerBossBars().remove(bossBar.getUuid());
                     break;
             }
-            connection.getProxyPlayer().getConnection().write(packet);
+            connection.getPlayer().getConnection().write(packet);
         } else if (packet instanceof PluginMessage) {
             PluginMessage pm = (PluginMessage) packet;
             if (!canForwardPluginMessage(pm)) {
@@ -50,45 +63,52 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
             }
 
             if (PluginMessageUtil.isMCBrand(pm)) {
-                connection.getProxyPlayer().getConnection().write(PluginMessageUtil.rewriteMCBrand(pm));
+                connection.getPlayer().getConnection().write(PluginMessageUtil.rewriteMCBrand(pm));
                 return;
             }
 
-            connection.getProxyPlayer().getConnection().write(pm);
+            MessageHandler.ForwardStatus status = VelocityServer.getServer().getChannelRegistrar().handlePluginMessage(
+                    connection, ChannelSide.FROM_SERVER, pm);
+            if (status == MessageHandler.ForwardStatus.FORWARD) {
+                connection.getPlayer().getConnection().write(pm);
+            }
         } else {
             // Just forward the packet on. We don't have anything to handle at this time.
-            if (packet instanceof ScoreboardTeam ||
-                    packet instanceof ScoreboardObjective ||
-                    packet instanceof ScoreboardSetScore ||
-                    packet instanceof ScoreboardDisplay) {
-                playerHandler.handleServerScoreboardPacket(packet);
-            }
-            connection.getProxyPlayer().getConnection().write(packet);
+            connection.getPlayer().getConnection().write(packet);
         }
     }
 
     @Override
     public void handleUnknown(ByteBuf buf) {
+        if (!connection.getPlayer().isActive()) {
+            // Connection was left open accidentally. Close it so as to avoid "You logged in from another location"
+            // errors.
+            connection.getMinecraftConnection().close();
+            return;
+        }
+
         ClientPlaySessionHandler playerHandler =
-                (ClientPlaySessionHandler) connection.getProxyPlayer().getConnection().getSessionHandler();
+                (ClientPlaySessionHandler) connection.getPlayer().getConnection().getSessionHandler();
         ByteBuf remapped = playerHandler.getIdRemapper().remap(buf, ProtocolConstants.Direction.CLIENTBOUND);
-        connection.getProxyPlayer().getConnection().write(remapped);
+        connection.getPlayer().getConnection().write(remapped);
     }
 
     @Override
     public void exception(Throwable throwable) {
-        connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(), throwable);
+        connection.getPlayer().handleConnectionException(connection.getServerInfo(), throwable);
     }
 
     private boolean canForwardPluginMessage(PluginMessage message) {
         ClientPlaySessionHandler playerHandler =
-                (ClientPlaySessionHandler) connection.getProxyPlayer().getConnection().getSessionHandler();
+                (ClientPlaySessionHandler) connection.getPlayer().getConnection().getSessionHandler();
         if (connection.getMinecraftConnection().getProtocolVersion() <= ProtocolConstants.MINECRAFT_1_12_2) {
             return message.getChannel().startsWith("MC|") ||
-                    playerHandler.getClientPluginMsgChannels().contains(message.getChannel());
+                    playerHandler.getClientPluginMsgChannels().contains(message.getChannel()) ||
+                    VelocityServer.getServer().getChannelRegistrar().registered(message.getChannel());
         } else {
             return message.getChannel().startsWith("minecraft:") ||
-                    playerHandler.getClientPluginMsgChannels().contains(message.getChannel());
+                    playerHandler.getClientPluginMsgChannels().contains(message.getChannel()) ||
+                    VelocityServer.getServer().getChannelRegistrar().registered(message.getChannel());
         }
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/LoginSessionHandler.java

@@ -2,11 +2,12 @@ package com.velocitypowered.proxy.connection.backend;
 
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.proxy.config.IPForwardingMode;
+import com.velocitypowered.proxy.config.PlayerInfoForwarding;
+import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
-import com.velocitypowered.proxy.data.GameProfile;
+import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
@@ -14,49 +15,40 @@ import com.velocitypowered.proxy.protocol.packet.*;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
-import io.netty.channel.ChannelPipeline;
 import net.kyori.text.TextComponent;
 
-import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.TimeUnit;
+import javax.crypto.Mac;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.util.concurrent.CompletableFuture;
 
 public class LoginSessionHandler implements MinecraftSessionHandler {
-    private final ServerConnection connection;
-    private ScheduledFuture<?> forwardingCheckTask;
+    private final VelocityServerConnection connection;
+    private boolean informationForwarded;
 
-    public LoginSessionHandler(ServerConnection connection) {
+    public LoginSessionHandler(VelocityServerConnection connection) {
         this.connection = connection;
     }
 
-    @Override
-    public void activated() {
-        if (VelocityServer.getServer().getConfiguration().getIpForwardingMode() == IPForwardingMode.MODERN) {
-            forwardingCheckTask = connection.getMinecraftConnection().getChannel().eventLoop().schedule(() -> {
-                connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(),
-                        TextComponent.of("Your server did not send the forwarding request in time. Is it set up correctly?"));
-            }, 1, TimeUnit.SECONDS);
-        }
-    }
-
     @Override
     public void handle(MinecraftPacket packet) {
         if (packet instanceof EncryptionRequest) {
             throw new IllegalStateException("Backend server is online-mode!");
         } else if (packet instanceof LoginPluginMessage) {
             LoginPluginMessage message = (LoginPluginMessage) packet;
-            if (VelocityServer.getServer().getConfiguration().getIpForwardingMode() == IPForwardingMode.MODERN &&
+            VelocityConfiguration configuration = VelocityServer.getServer().getConfiguration();
+            if (configuration.getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN &&
                     message.getChannel().equals(VelocityConstants.VELOCITY_IP_FORWARDING_CHANNEL)) {
                 LoginPluginResponse response = new LoginPluginResponse();
                 response.setSuccess(true);
                 response.setId(message.getId());
-                response.setData(createForwardingData(connection.getProxyPlayer().getRemoteAddress().getHostString(),
-                        connection.getProxyPlayer().getProfile()));
+                response.setData(createForwardingData(configuration.getForwardingSecret(),
+                        connection.getPlayer().getRemoteAddress().getHostString(),
+                        connection.getPlayer().getProfile()));
                 connection.getMinecraftConnection().write(response);
-                cancelForwardingCheck();
-
-                ServerLogin login = new ServerLogin();
-                login.setUsername(connection.getProxyPlayer().getUsername());
-                connection.getMinecraftConnection().write(login);
+                informationForwarded = true;
             } else {
                 // Don't understand
                 LoginPluginResponse response = new LoginPluginResponse();
@@ -67,78 +59,92 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
             }
         } else if (packet instanceof Disconnect) {
             Disconnect disconnect = (Disconnect) packet;
-            connection.disconnect();
-
             // Do we have an outstanding notification? If so, fulfill it.
             doNotify(ConnectionRequestResults.forDisconnect(disconnect));
-
-            connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(), disconnect);
+            connection.disconnect();
         } else if (packet instanceof SetCompression) {
             SetCompression sc = (SetCompression) packet;
             connection.getMinecraftConnection().setCompressionThreshold(sc.getThreshold());
         } else if (packet instanceof ServerLoginSuccess) {
+            if (VelocityServer.getServer().getConfiguration().getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN &&
+                    !informationForwarded) {
+                doNotify(ConnectionRequestResults.forDisconnect(
+                        TextComponent.of("Your server did not send a forwarding request to the proxy. Is it set up correctly?")));
+                connection.disconnect();
+                return;
+            }
+
             // The player has been logged on to the backend server.
             connection.getMinecraftConnection().setState(StateRegistry.PLAY);
-            ServerConnection existingConnection = connection.getProxyPlayer().getConnectedServer();
+            VelocityServerConnection existingConnection = connection.getPlayer().getConnectedServer();
             if (existingConnection == null) {
                 // Strap on the play session handler
-                connection.getProxyPlayer().getConnection().setSessionHandler(new ClientPlaySessionHandler(connection.getProxyPlayer()));
+                connection.getPlayer().getConnection().setSessionHandler(new ClientPlaySessionHandler(connection.getPlayer()));
             } else {
                 // The previous server connection should become obsolete.
                 existingConnection.disconnect();
             }
 
-            // Do we have an outstanding notification? If so, fulfill it.
             doNotify(ConnectionRequestResults.SUCCESSFUL);
-
             connection.getMinecraftConnection().setSessionHandler(new BackendPlaySessionHandler(connection));
-            connection.getProxyPlayer().setConnectedServer(connection);
+            connection.getPlayer().setConnectedServer(connection);
         }
     }
 
-    @Override
-    public void deactivated() {
-        cancelForwardingCheck();
-    }
-
     @Override
     public void exception(Throwable throwable) {
-        connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(), throwable);
+        CompletableFuture<ConnectionRequestBuilder.Result> future = connection.getMinecraftConnection().getChannel()
+                .attr(VelocityServerConnection.CONNECTION_NOTIFIER).getAndSet(null);
+        if (future != null) {
+            future.completeExceptionally(throwable);
+        }
     }
 
     private void doNotify(ConnectionRequestBuilder.Result result) {
-        ChannelPipeline pipeline = connection.getMinecraftConnection().getChannel().pipeline();
-        ServerConnection.ConnectionNotifier n = pipeline.get(ServerConnection.ConnectionNotifier.class);
-        if (n != null) {
-            n.getResult().complete(result);
-            pipeline.remove(ServerConnection.ConnectionNotifier.class);
+        CompletableFuture<ConnectionRequestBuilder.Result> future = connection.getMinecraftConnection().getChannel()
+                .attr(VelocityServerConnection.CONNECTION_NOTIFIER).getAndSet(null);
+        if (future != null) {
+            future.complete(result);
         }
     }
 
-    private void cancelForwardingCheck() {
-        if (forwardingCheckTask != null) {
-            forwardingCheckTask.cancel(false);
-            forwardingCheckTask = null;
-        }
-    }
-
-    private static ByteBuf createForwardingData(String address, GameProfile profile) {
-        ByteBuf buf = Unpooled.buffer();
-        ProtocolUtils.writeString(buf, address);
-        ProtocolUtils.writeUuid(buf, profile.idAsUuid());
-        ProtocolUtils.writeString(buf, profile.getName());
-        ProtocolUtils.writeVarInt(buf, profile.getProperties().size());
-        for (GameProfile.Property property : profile.getProperties()) {
-            ProtocolUtils.writeString(buf, property.getName());
-            ProtocolUtils.writeString(buf, property.getValue());
-            String signature = property.getSignature();
-            if (signature != null) {
-                buf.writeBoolean(true);
-                ProtocolUtils.writeString(buf, signature);
-            } else {
-                buf.writeBoolean(false);
+    static ByteBuf createForwardingData(byte[] hmacSecret, String address, GameProfile profile) {
+        ByteBuf dataToForward = Unpooled.buffer();
+        ByteBuf finalData = Unpooled.buffer();
+        try {
+            ProtocolUtils.writeString(dataToForward, address);
+            ProtocolUtils.writeUuid(dataToForward, profile.idAsUuid());
+            ProtocolUtils.writeString(dataToForward, profile.getName());
+            ProtocolUtils.writeVarInt(dataToForward, profile.getProperties().size());
+            for (GameProfile.Property property : profile.getProperties()) {
+                ProtocolUtils.writeString(dataToForward, property.getName());
+                ProtocolUtils.writeString(dataToForward, property.getValue());
+                String signature = property.getSignature();
+                if (signature != null) {
+                    dataToForward.writeBoolean(true);
+                    ProtocolUtils.writeString(dataToForward, signature);
+                } else {
+                    dataToForward.writeBoolean(false);
+                }
             }
+
+            SecretKey key = new SecretKeySpec(hmacSecret, "HmacSHA256");
+            Mac mac = Mac.getInstance("HmacSHA256");
+            mac.init(key);
+            mac.update(dataToForward.array(), dataToForward.arrayOffset(), dataToForward.readableBytes());
+            byte[] sig = mac.doFinal();
+            finalData.writeBytes(sig);
+            finalData.writeBytes(dataToForward);
+            return finalData;
+        } catch (InvalidKeyException e) {
+            finalData.release();
+            throw new RuntimeException("Unable to authenticate data", e);
+        } catch (NoSuchAlgorithmException e) {
+            // Should never happen
+            finalData.release();
+            throw new AssertionError(e);
+        } finally {
+            dataToForward.release();
         }
-        return buf;
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/VelocityServerConnection.java

@@ -1,44 +1,49 @@
 package com.velocitypowered.proxy.connection.backend;
 
+import com.google.common.base.Preconditions;
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
-import com.velocitypowered.proxy.config.IPForwardingMode;
+import com.velocitypowered.api.proxy.ServerConnection;
+import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
+import com.velocitypowered.proxy.config.PlayerInfoForwarding;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
-import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftVarintFrameDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftVarintLengthEncoder;
 import com.velocitypowered.proxy.protocol.packet.Handshake;
+import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import com.velocitypowered.proxy.protocol.packet.ServerLogin;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.protocol.StateRegistry;
-import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import io.netty.channel.*;
 import io.netty.handler.timeout.ReadTimeoutHandler;
+import io.netty.util.AttributeKey;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
 
-import static com.velocitypowered.network.Connections.FRAME_DECODER;
-import static com.velocitypowered.network.Connections.FRAME_ENCODER;
-import static com.velocitypowered.network.Connections.HANDLER;
-import static com.velocitypowered.network.Connections.MINECRAFT_DECODER;
-import static com.velocitypowered.network.Connections.MINECRAFT_ENCODER;
-import static com.velocitypowered.network.Connections.READ_TIMEOUT;
-import static com.velocitypowered.network.Connections.SERVER_READ_TIMEOUT_SECONDS;
+import static com.velocitypowered.proxy.network.Connections.FRAME_DECODER;
+import static com.velocitypowered.proxy.network.Connections.FRAME_ENCODER;
+import static com.velocitypowered.proxy.network.Connections.HANDLER;
+import static com.velocitypowered.proxy.network.Connections.MINECRAFT_DECODER;
+import static com.velocitypowered.proxy.network.Connections.MINECRAFT_ENCODER;
+import static com.velocitypowered.proxy.network.Connections.READ_TIMEOUT;
+import static com.velocitypowered.proxy.network.Connections.SERVER_READ_TIMEOUT_SECONDS;
 
-public class ServerConnection implements MinecraftConnectionAssociation {
-    static final String CONNECTION_NOTIFIER = "connection-notifier";
+public class VelocityServerConnection implements MinecraftConnectionAssociation, ServerConnection {
+    static final AttributeKey<CompletableFuture<ConnectionRequestBuilder.Result>> CONNECTION_NOTIFIER =
+            AttributeKey.newInstance("connection-notification-result");
 
     private final ServerInfo serverInfo;
     private final ConnectedPlayer proxyPlayer;
     private final VelocityServer server;
     private MinecraftConnection minecraftConnection;
 
-    public ServerConnection(ServerInfo target, ConnectedPlayer proxyPlayer, VelocityServer server) {
+    public VelocityServerConnection(ServerInfo target, ConnectedPlayer proxyPlayer, VelocityServer server) {
         this.serverInfo = target;
         this.proxyPlayer = proxyPlayer;
         this.server = server;
@@ -55,12 +60,12 @@ public class ServerConnection implements MinecraftConnectionAssociation {
                                 .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
                                 .addLast(FRAME_ENCODER, MinecraftVarintLengthEncoder.INSTANCE)
                                 .addLast(MINECRAFT_DECODER, new MinecraftDecoder(ProtocolConstants.Direction.CLIENTBOUND))
-                                .addLast(MINECRAFT_ENCODER, new MinecraftEncoder(ProtocolConstants.Direction.SERVERBOUND))
-                                .addLast(CONNECTION_NOTIFIER, new ConnectionNotifier(result));
+                                .addLast(MINECRAFT_ENCODER, new MinecraftEncoder(ProtocolConstants.Direction.SERVERBOUND));
 
+                        ch.attr(CONNECTION_NOTIFIER).set(result);
                         MinecraftConnection connection = new MinecraftConnection(ch);
                         connection.setState(StateRegistry.HANDSHAKE);
-                        connection.setAssociation(ServerConnection.this);
+                        connection.setAssociation(VelocityServerConnection.this);
                         ch.pipeline().addLast(HANDLER, connection);
                     }
                 })
@@ -72,7 +77,7 @@ public class ServerConnection implements MinecraftConnectionAssociation {
                             minecraftConnection = future.channel().pipeline().get(MinecraftConnection.class);
 
                             // Kick off the connection process
-                            minecraftConnection.setSessionHandler(new LoginSessionHandler(ServerConnection.this));
+                            minecraftConnection.setSessionHandler(new LoginSessionHandler(VelocityServerConnection.this));
                             startHandshake();
                         } else {
                             result.completeExceptionally(future.cause());
@@ -93,11 +98,13 @@ public class ServerConnection implements MinecraftConnectionAssociation {
     }
 
     private void startHandshake() {
+        PlayerInfoForwarding forwardingMode = VelocityServer.getServer().getConfiguration().getPlayerInfoForwardingMode();
+
         // Initiate a handshake.
         Handshake handshake = new Handshake();
         handshake.setNextStatus(StateRegistry.LOGIN_ID);
         handshake.setProtocolVersion(proxyPlayer.getConnection().getProtocolVersion());
-        if (VelocityServer.getServer().getConfiguration().getIpForwardingMode() == IPForwardingMode.LEGACY) {
+        if (forwardingMode == PlayerInfoForwarding.LEGACY) {
             handshake.setServerAddress(createBungeeForwardingAddress());
         } else {
             handshake.setServerAddress(serverInfo.getAddress().getHostString());
@@ -109,17 +116,9 @@ public class ServerConnection implements MinecraftConnectionAssociation {
         minecraftConnection.setProtocolVersion(protocolVersion);
         minecraftConnection.setState(StateRegistry.LOGIN);
 
-        // Send the server login packet for <=1.12.2 and for 1.13+ servers not using "modern" forwarding.
-        if (protocolVersion <= ProtocolConstants.MINECRAFT_1_12_2 ||
-                VelocityServer.getServer().getConfiguration().getIpForwardingMode() != IPForwardingMode.MODERN) {
-            ServerLogin login = new ServerLogin();
-            login.setUsername(proxyPlayer.getUsername());
-            minecraftConnection.write(login);
-        }
-    }
-
-    public ConnectedPlayer getProxyPlayer() {
-        return proxyPlayer;
+        ServerLogin login = new ServerLogin();
+        login.setUsername(proxyPlayer.getUsername());
+        minecraftConnection.write(login);
     }
 
     public MinecraftConnection getMinecraftConnection() {
@@ -130,6 +129,11 @@ public class ServerConnection implements MinecraftConnectionAssociation {
         return serverInfo;
     }
 
+    @Override
+    public ConnectedPlayer getPlayer() {
+        return proxyPlayer;
+    }
+
     public void disconnect() {
         minecraftConnection.close();
         minecraftConnection = null;
@@ -140,24 +144,13 @@ public class ServerConnection implements MinecraftConnectionAssociation {
         return "[server connection] " + proxyPlayer.getProfile().getName() + " -> " + serverInfo.getName();
     }
 
-    static class ConnectionNotifier extends ChannelInboundHandlerAdapter {
-        private final CompletableFuture<ConnectionRequestBuilder.Result> result;
-
-        public ConnectionNotifier(CompletableFuture<ConnectionRequestBuilder.Result> result) {
-            this.result = result;
-        }
-
-        public CompletableFuture<ConnectionRequestBuilder.Result> getResult() {
-            return result;
-        }
-
-        public void onComplete() {
-            result.complete(ConnectionRequestResults.SUCCESSFUL);
-        }
-
-        @Override
-        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-            result.completeExceptionally(cause);
-        }
+    @Override
+    public void sendPluginMessage(ChannelIdentifier identifier, byte[] data) {
+        Preconditions.checkNotNull(identifier, "identifier");
+        Preconditions.checkNotNull(data, "data");
+        PluginMessage message = new PluginMessage();
+        message.setChannel(identifier.getId());
+        message.setData(data);
+        minecraftConnection.write(message);
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -1,47 +1,41 @@
 package com.velocitypowered.proxy.connection.client;
 
+import com.velocitypowered.api.event.connection.DisconnectEvent;
+import com.velocitypowered.api.proxy.messages.ChannelSide;
+import com.velocitypowered.api.proxy.messages.MessageHandler;
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.proxy.connection.backend.ServerConnection;
-import com.velocitypowered.api.server.ServerInfo;
-import com.velocitypowered.proxy.data.scoreboard.Objective;
-import com.velocitypowered.proxy.data.scoreboard.Score;
-import com.velocitypowered.proxy.data.scoreboard.Scoreboard;
-import com.velocitypowered.proxy.data.scoreboard.Team;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
-import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packet.*;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.remap.EntityIdRemapper;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import com.velocitypowered.proxy.util.ThrowableUtils;
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.Unpooled;
 import io.netty.channel.EventLoop;
-import io.netty.util.ReferenceCountUtil;
 import net.kyori.text.TextComponent;
 import net.kyori.text.format.TextColor;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
-import java.net.InetSocketAddress;
 import java.util.*;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 
+/**
+ * Handles communication with the connected Minecraft client. This is effectively the primary nerve center that
+ * joins backend servers with players.
+ */
 public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     private static final Logger logger = LogManager.getLogger(ClientPlaySessionHandler.class);
     private static final int MAX_PLUGIN_CHANNELS = 128;
 
     private final ConnectedPlayer player;
-    private ScheduledFuture<?> pingTask;
     private long lastPing = -1;
     private boolean spawned = false;
     private final List<UUID> serverBossBars = new ArrayList<>();
     private final Set<String> clientPluginMsgChannels = new HashSet<>();
-    private int currentDimension;
-    private Scoreboard serverScoreboard = new Scoreboard();
     private EntityIdRemapper idRemapper;
 
     public ClientPlaySessionHandler(ConnectedPlayer player) {
@@ -50,16 +44,13 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
     @Override
     public void activated() {
-        EventLoop loop = player.getConnection().getChannel().eventLoop();
-        pingTask = loop.scheduleAtFixedRate(this::ping, 5, 15, TimeUnit.SECONDS);
-    }
-
-    private void ping() {
-        long randomId = ThreadLocalRandom.current().nextInt();
-        lastPing = randomId;
-        KeepAlive keepAlive = new KeepAlive();
-        keepAlive.setRandomId(randomId);
-        player.getConnection().write(keepAlive);
+        PluginMessage message;
+        if (player.getProtocolVersion() >= ProtocolConstants.MINECRAFT_1_13) {
+            message = PluginMessageUtil.constructChannelsPacket("minecraft:register", VelocityServer.getServer().getChannelRegistrar().getModernChannelIds());
+        } else {
+            message = PluginMessageUtil.constructChannelsPacket("REGISTER", VelocityServer.getServer().getChannelRegistrar().getLegacyChannelIds());
+        }
+        player.getConnection().write(message);
     }
 
     @Override
@@ -67,11 +58,10 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         if (packet instanceof KeepAlive) {
             KeepAlive keepAlive = (KeepAlive) packet;
             if (keepAlive.getRandomId() != lastPing) {
-                throw new IllegalStateException("Client sent invalid keepAlive; expected " + lastPing + ", got " + keepAlive.getRandomId());
+                // The last keep alive we got was probably from a different server. Let's ignore it, and hope the next
+                // ping is alright.
+                return;
             }
-
-            // Do not forward the packet to the player's server, because we handle pings for all servers already.
-            return;
         }
 
         if (packet instanceof ClientSettings) {
@@ -80,10 +70,49 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         }
 
         if (packet instanceof Chat) {
+            // Try to handle any commands on the proxy. If that fails, send it onto the client.
             Chat chat = (Chat) packet;
-            if (chat.getMessage().equals("/connect")) {
-                ServerInfo info = new ServerInfo("test", new InetSocketAddress("localhost", 25566));
-                player.createConnectionRequest(info).fireAndForget();
+            String msg = ((Chat) packet).getMessage();
+            if (msg.startsWith("/")) {
+                try {
+                    if (!VelocityServer.getServer().getCommandManager().execute(player, msg.substring(1))) {
+                        player.getConnectedServer().getMinecraftConnection().write(chat);
+                    }
+                } catch (Exception e) {
+                    logger.info("Exception occurred while running command for {}", player.getProfile().getName(), e);
+                    player.sendMessage(TextComponent.of("An error occurred while running this command.", TextColor.RED));
+                    return;
+                }
+            } else {
+                player.getConnectedServer().getMinecraftConnection().write(chat);
+            }
+            return;
+        }
+
+        if (packet instanceof TabCompleteRequest) {
+            TabCompleteRequest req = (TabCompleteRequest) packet;
+            int lastSpace = req.getCommand().indexOf(' ');
+            if (!req.isAssumeCommand() && lastSpace != -1) {
+                String command = req.getCommand().substring(1);
+                try {
+                    Optional<List<String>> offers = VelocityServer.getServer().getCommandManager().offerSuggestions(player, command);
+                    if (offers.isPresent()) {
+                        TabCompleteResponse response = new TabCompleteResponse();
+                        response.setTransactionId(req.getTransactionId());
+                        response.setStart(lastSpace);
+                        response.setLength(req.getCommand().length() - lastSpace);
+
+                        for (String s : offers.get()) {
+                            response.getOffers().add(new TabCompleteResponse.Offer(s, null));
+                        }
+
+                        player.getConnection().write(response);
+                    } else {
+                        player.getConnectedServer().getMinecraftConnection().write(packet);
+                    }
+                } catch (Exception e) {
+                    logger.error("Unable to provide tab list completions for " + player.getUsername() + " for command '" + req.getCommand() + "'", e);
+                }
                 return;
             }
         }
@@ -106,11 +135,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     @Override
     public void disconnected() {
         player.teardown();
-
-        if (pingTask != null && !pingTask.isCancelled()) {
-            pingTask.cancel(false);
-            pingTask = null;
-        }
+        VelocityServer.getServer().getEventManager().fireAndForget(new DisconnectEvent(player));
     }
 
     @Override
@@ -123,21 +148,22 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     }
 
     public void handleBackendJoinGame(JoinGame joinGame) {
+        lastPing = Long.MIN_VALUE; // reset last ping
         if (!spawned) {
             // nothing special to do here
             spawned = true;
-            currentDimension = joinGame.getDimension();
             player.getConnection().delayedWrite(joinGame);
             idRemapper = EntityIdRemapper.getMapper(joinGame.getEntityId(), player.getConnection().getProtocolVersion());
         } else {
-            // In order to handle switching to another server we will need send three packets:
+            // Ah, this is the meat and potatoes of the whole venture!
+            //
+            // In order to handle switching to another server, you will need to send three packets:
             //
             // - The join game packet from the backend server
             // - A respawn packet with a different dimension
             // - Another respawn with the correct dimension
             //
-            // We can't simply ignore the packet with the different dimension. If you try to be smart about it it doesn't
-            // work.
+            // The two respawns with different dimensions are required, otherwise the client gets confused.
             //
             // Most notably, by having the client accept the join game packet, we can work around the need to perform
             // entity ID rewrites, eliminating potential issues from rewriting packets and improving compatibility with
@@ -147,13 +173,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
             int tempDim = joinGame.getDimension() == 0 ? -1 : 0;
             player.getConnection().delayedWrite(new Respawn(tempDim, joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType()));
             player.getConnection().delayedWrite(new Respawn(joinGame.getDimension(), joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType()));
-            currentDimension = joinGame.getDimension();
-        }
-
-        // Resend client settings packet to remote server if we have it, this preserves client settings across
-        // transitions.
-        if (player.getClientSettings() != null) {
-            player.getConnectedServer().getMinecraftConnection().delayedWrite(player.getClientSettings());
         }
 
         // Remove old boss bars.
@@ -165,15 +184,18 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         }
         serverBossBars.clear();
 
-        // Remove scoreboard junk.
-        clearServerScoreboard();
-
         // Tell the server about this client's plugin messages. Velocity will forward them on to the client.
-        if (!clientPluginMsgChannels.isEmpty()) {
+        Collection<String> toRegister = new HashSet<>(clientPluginMsgChannels);
+        if (player.getProtocolVersion() >= ProtocolConstants.MINECRAFT_1_13) {
+            toRegister.addAll(VelocityServer.getServer().getChannelRegistrar().getModernChannelIds());
+        } else {
+            toRegister.addAll(VelocityServer.getServer().getChannelRegistrar().getLegacyChannelIds());
+        }
+        if (!toRegister.isEmpty()) {
             String channel = player.getConnection().getProtocolVersion() >= ProtocolConstants.MINECRAFT_1_13 ?
                     "minecraft:register" : "REGISTER";
-            player.getConnectedServer().getMinecraftConnection().delayedWrite(
-                    PluginMessageUtil.constructChannelsPacket(channel, clientPluginMsgChannels));
+            player.getConnectedServer().getMinecraftConnection().delayedWrite(PluginMessageUtil.constructChannelsPacket(
+                    channel, toRegister));
         }
 
         // Flush everything
@@ -181,10 +203,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         player.getConnectedServer().getMinecraftConnection().flush();
     }
 
-    public void setCurrentDimension(int currentDimension) {
-        this.currentDimension = currentDimension;
-    }
-
     public List<UUID> getServerBossBars() {
         return serverBossBars;
     }
@@ -204,7 +222,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
             }
 
             if (actuallyRegistered.size() > 0) {
-                logger.info("Rewritten register packet: {}", actuallyRegistered);
                 PluginMessage newRegisterPacket = PluginMessageUtil.constructChannelsPacket(packet.getChannel(), actuallyRegistered);
                 player.getConnectedServer().getMinecraftConnection().write(newRegisterPacket);
             }
@@ -222,88 +239,12 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
             return;
         }
 
-        // We're going to forward on the original packet.
-        player.getConnectedServer().getMinecraftConnection().write(packet);
-    }
-
-    public void handleServerScoreboardPacket(MinecraftPacket packet) {
-        if (packet instanceof ScoreboardDisplay) {
-            ScoreboardDisplay sd = (ScoreboardDisplay) packet;
-            serverScoreboard.setPosition(sd.getPosition());
-            serverScoreboard.setDisplayName(sd.getDisplayName());
+        MessageHandler.ForwardStatus status = VelocityServer.getServer().getChannelRegistrar().handlePluginMessage(
+                player, ChannelSide.FROM_CLIENT, packet);
+        if (status == MessageHandler.ForwardStatus.FORWARD) {
+            // We're going to forward on the original packet.
+            player.getConnectedServer().getMinecraftConnection().write(packet);
         }
-
-        if (packet instanceof ScoreboardObjective) {
-            ScoreboardObjective so = (ScoreboardObjective) packet;
-            switch (so.getMode()) {
-                case ScoreboardObjective.ADD:
-                    Objective o = new Objective(so.getId());
-                    o.setDisplayName(so.getDisplayName());
-                    o.setType(so.getType());
-                    serverScoreboard.getObjectives().put(so.getId(), o);
-                    break;
-                case ScoreboardObjective.REMOVE:
-                    serverScoreboard.getObjectives().remove(so.getId());
-                    break;
-            }
-        }
-
-        if (packet instanceof ScoreboardSetScore) {
-            ScoreboardSetScore sss = (ScoreboardSetScore) packet;
-            Objective objective = serverScoreboard.getObjectives().get(sss.getObjective());
-            if (objective == null) {
-                return;
-            }
-            switch (sss.getAction()) {
-                case ScoreboardSetScore.CHANGE:
-                    Score score = new Score(sss.getEntity(), sss.getValue());
-                    objective.getScores().put(sss.getEntity(), score);
-                    break;
-                case ScoreboardSetScore.REMOVE:
-                    objective.getScores().remove(sss.getEntity());
-                    break;
-            }
-        }
-
-        if (packet instanceof ScoreboardTeam) {
-            ScoreboardTeam st = (ScoreboardTeam) packet;
-            switch (st.getMode()) {
-                case ScoreboardTeam.ADD:
-                    // TODO: Preserve other team information? We might not need to...
-                    Team team = new Team(st.getId());
-                    serverScoreboard.getTeams().put(st.getId(), team);
-                    break;
-                case ScoreboardTeam.REMOVE:
-                    serverScoreboard.getTeams().remove(st.getId());
-                    break;
-            }
-        }
-    }
-
-    private void clearServerScoreboard() {
-        for (Objective objective : serverScoreboard.getObjectives().values()) {
-            for (Score score : objective.getScores().values()) {
-                ScoreboardSetScore sss = new ScoreboardSetScore();
-                sss.setObjective(objective.getId());
-                sss.setAction(ScoreboardSetScore.REMOVE);
-                sss.setEntity(score.getTarget());
-                player.getConnection().delayedWrite(sss);
-            }
-
-            ScoreboardObjective so = new ScoreboardObjective();
-            so.setId(objective.getId());
-            so.setMode(ScoreboardObjective.REMOVE);
-            player.getConnection().delayedWrite(so);
-        }
-
-        for (Team team : serverScoreboard.getTeams().values()) {
-            ScoreboardTeam st = new ScoreboardTeam();
-            st.setId(team.getId());
-            st.setMode(ScoreboardTeam.REMOVE);
-            player.getConnection().delayedWrite(st);
-        }
-
-        serverScoreboard = new Scoreboard();
     }
 
     public Set<String> getClientPluginMsgChannels() {
@@ -313,4 +254,8 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     public EntityIdRemapper getIdRemapper() {
         return idRemapper;
     }
+
+    public void setLastPing(long lastPing) {
+        this.lastPing = lastPing;
+    }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -2,21 +2,29 @@ package com.velocitypowered.proxy.connection.client;
 
 import com.google.common.base.Preconditions;
 import com.google.gson.JsonObject;
+import com.velocitypowered.api.event.player.ServerPreConnectEvent;
+import com.velocitypowered.api.permission.PermissionFunction;
+import com.velocitypowered.api.permission.PermissionProvider;
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
+import com.velocitypowered.api.proxy.ServerConnection;
+import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.util.MessagePosition;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
-import com.velocitypowered.proxy.data.GameProfile;
+import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
-import com.velocitypowered.proxy.connection.backend.ServerConnection;
+import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
+import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import com.velocitypowered.proxy.util.ThrowableUtils;
-import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
+import com.velocitypowered.proxy.protocol.packet.HeaderAndFooter;
+
 import net.kyori.text.Component;
 import net.kyori.text.TextComponent;
 import net.kyori.text.TranslatableComponent;
@@ -25,8 +33,8 @@ import net.kyori.text.serializer.ComponentSerializers;
 import net.kyori.text.serializer.PlainComponentSerializer;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
-import javax.annotation.Nonnull;
 import java.net.InetSocketAddress;
 import java.util.List;
 import java.util.Optional;
@@ -35,19 +43,23 @@ import java.util.concurrent.CompletableFuture;
 
 public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     private static final PlainComponentSerializer PASS_THRU_TRANSLATE = new PlainComponentSerializer((c) -> "", TranslatableComponent::key);
+    public static final PermissionProvider DEFAULT_PERMISSIONS = s -> PermissionFunction.ALWAYS_UNDEFINED;
 
     private static final Logger logger = LogManager.getLogger(ConnectedPlayer.class);
 
-    private final GameProfile profile;
     private final MinecraftConnection connection;
+    private final InetSocketAddress virtualHost;
+    private final GameProfile profile;
+    private PermissionFunction permissionFunction = null;
     private int tryIndex = 0;
-    private ServerConnection connectedServer;
+    private VelocityServerConnection connectedServer;
     private ClientSettings clientSettings;
-    private ServerConnection connectionInFlight;
+    private VelocityServerConnection connectionInFlight;
 
-    public ConnectedPlayer(GameProfile profile, MinecraftConnection connection) {
+    public ConnectedPlayer(GameProfile profile, MinecraftConnection connection, InetSocketAddress virtualHost) {
         this.profile = profile;
         this.connection = connection;
+        this.virtualHost = virtualHost;
     }
 
     @Override
@@ -61,8 +73,8 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     }
 
     @Override
-    public Optional<ServerInfo> getCurrentServer() {
-        return connectedServer != null ? Optional.of(connectedServer.getServerInfo()) : Optional.empty();
+    public Optional<ServerConnection> getCurrentServer() {
+        return Optional.ofNullable(connectedServer);
     }
 
     public GameProfile getProfile() {
@@ -78,13 +90,27 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         return (InetSocketAddress) connection.getChannel().remoteAddress();
     }
 
+    @Override
+    public Optional<InetSocketAddress> getVirtualHost() {
+        return Optional.ofNullable(virtualHost);
+    }
+
+    public void setPermissionFunction(PermissionFunction permissionFunction) {
+        this.permissionFunction = permissionFunction;
+    }
+
     @Override
     public boolean isActive() {
         return connection.getChannel().isActive();
     }
 
     @Override
-    public void sendMessage(@Nonnull Component component, @Nonnull MessagePosition position) {
+    public int getProtocolVersion() {
+        return connection.getProtocolVersion();
+    }
+
+    @Override
+    public void sendMessage(@NonNull Component component, @NonNull MessagePosition position) {
         Preconditions.checkNotNull(component, "component");
         Preconditions.checkNotNull(position, "position");
 
@@ -107,11 +133,28 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     }
 
     @Override
-    public ConnectionRequestBuilder createConnectionRequest(@Nonnull ServerInfo info) {
+    public ConnectionRequestBuilder createConnectionRequest(@NonNull ServerInfo info) {
         return new ConnectionRequestBuilderImpl(info);
     }
 
-    public ServerConnection getConnectedServer() {
+    @Override
+    public void setHeaderAndFooter(@NonNull Component header, @NonNull Component footer) {
+        Preconditions.checkNotNull(header, "header");
+        Preconditions.checkNotNull(footer, "footer");
+        connection.write(HeaderAndFooter.create(header, footer));
+    }
+
+    @Override
+    public void clearHeaderAndFooter() {
+        connection.write(HeaderAndFooter.reset());
+    }
+    
+    @Override
+    public void disconnect(Component reason) {
+        connection.closeWith(Disconnect.create(reason));
+    }
+
+    public VelocityServerConnection getConnectedServer() {
         return connectedServer;
     }
 
@@ -127,7 +170,6 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         String error = ThrowableUtils.briefDescription(throwable);
         String userMessage;
         if (connectedServer != null && connectedServer.getServerInfo().equals(info)) {
-            logger.error("{}: exception occurred in connection to {}", this, info.getName(), throwable);
             userMessage = "Exception in server " + info.getName();
         } else {
             logger.error("{}: unable to connect to server {}", this, info.getName(), throwable);
@@ -153,9 +195,17 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
 
     public void handleConnectionException(ServerInfo info, Component disconnectReason) {
         connectionInFlight = null;
-        if (connectedServer == null || connectedServer.getServerInfo().equals(info)) {
-            // The player isn't yet connected to a server or they are already connected to the server
-            // they're disconnected from.
+        if (connectedServer == null) {
+            // The player isn't yet connected to a server.
+            Optional<ServerInfo> nextServer = getNextServerToTry();
+            if (nextServer.isPresent()) {
+                createConnectionRequest(nextServer.get()).fireAndForget();
+            } else {
+                connection.closeWith(Disconnect.create(disconnectReason));
+            }
+        } else if (connectedServer.getServerInfo().equals(info)) {
+            // Already connected to the server being disconnected from.
+            // TODO: ServerKickEvent
             connection.closeWith(Disconnect.create(disconnectReason));
         } else {
             connection.write(Chat.create(disconnectReason));
@@ -187,11 +237,20 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         }
 
         // Otherwise, initiate the connection.
-        ServerConnection connection = new ServerConnection(request.getServer(), this, VelocityServer.getServer());
-        return connection.connect();
+        ServerPreConnectEvent event = new ServerPreConnectEvent(this, ServerPreConnectEvent.ServerResult.allowed(request.getServer()));
+        return VelocityServer.getServer().getEventManager().fire(event)
+                .thenCompose((newEvent) -> {
+                    if (!newEvent.getResult().isAllowed()) {
+                        return CompletableFuture.completedFuture(
+                                ConnectionRequestResults.plainResult(ConnectionRequestBuilder.Status.CONNECTION_CANCELLED)
+                        );
+                    }
+
+                    return new VelocityServerConnection(newEvent.getResult().getInfo().get(), this, VelocityServer.getServer()).connect();
+                });
     }
 
-    public void setConnectedServer(ServerConnection serverConnection) {
+    public void setConnectedServer(VelocityServerConnection serverConnection) {
         if (this.connectedServer != null && !serverConnection.getServerInfo().equals(connectedServer.getServerInfo())) {
             this.tryIndex = 0;
         }
@@ -209,6 +268,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         if (connectedServer != null) {
             connectedServer.disconnect();
         }
+        VelocityServer.getServer().unregisterConnection(this);
     }
 
     @Override
@@ -216,10 +276,25 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         return "[connected player] " + getProfile().getName() + " (" + getRemoteAddress() + ")";
     }
 
+    @Override
+    public boolean hasPermission(String permission) {
+        return permissionFunction.getPermissionSetting(permission).asBoolean();
+    }
+
+    @Override
+    public void sendPluginMessage(ChannelIdentifier identifier, byte[] data) {
+        Preconditions.checkNotNull(identifier, "identifier");
+        Preconditions.checkNotNull(data, "data");
+        PluginMessage message = new PluginMessage();
+        message.setChannel(identifier.getId());
+        message.setData(data);
+        connection.write(message);
+    }
+
     private class ConnectionRequestBuilderImpl implements ConnectionRequestBuilder {
         private final ServerInfo info;
 
-        public ConnectionRequestBuilderImpl(ServerInfo info) {
+        ConnectionRequestBuilderImpl(ServerInfo info) {
             this.info = Preconditions.checkNotNull(info, "info");
         }
 
@@ -236,7 +311,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         @Override
         public void fireAndForget() {
             connect()
-                    .whenComplete((status, throwable) -> {
+                    .whenCompleteAsync((status, throwable) -> {
                         if (throwable != null) {
                             handleConnectionException(info, throwable);
                             return;
@@ -256,7 +331,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
                                 handleConnectionException(info, Disconnect.create(status.getReason().orElse(ConnectionMessages.INTERNAL_SERVER_CONNECTION_ERROR)));
                                 break;
                         }
-                    });
+                    }, connection.getChannel().eventLoop());
         }
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/HandshakeSessionHandler.java

@@ -1,14 +1,28 @@
 package com.velocitypowered.proxy.connection.client;
 
 import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.event.connection.ConnectionHandshakeEvent;
+import com.velocitypowered.api.event.proxy.ProxyPingEvent;
+import com.velocitypowered.api.proxy.InboundConnection;
+import com.velocitypowered.proxy.VelocityServer;
+import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.api.proxy.server.ServerPing;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
-import com.velocitypowered.proxy.protocol.packet.Disconnect;
-import com.velocitypowered.proxy.protocol.packet.Handshake;
+import com.velocitypowered.proxy.protocol.packet.*;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import net.kyori.text.TextComponent;
 import net.kyori.text.TranslatableComponent;
+import net.kyori.text.format.TextColor;
+
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.util.Optional;
 
 public class HandshakeSessionHandler implements MinecraftSessionHandler {
     private final MinecraftConnection connection;
@@ -19,16 +33,24 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
 
     @Override
     public void handle(MinecraftPacket packet) {
+        if (packet instanceof LegacyPing || packet instanceof LegacyHandshake) {
+            connection.setProtocolVersion(ProtocolConstants.LEGACY);
+            handleLegacy(packet);
+            return;
+        }
+
         if (!(packet instanceof Handshake)) {
             throw new IllegalArgumentException("Did not expect packet " + packet.getClass().getName());
         }
 
+        InitialInboundConnection ic = new InitialInboundConnection(connection, (Handshake) packet);
+
         Handshake handshake = (Handshake) packet;
         switch (handshake.getNextStatus()) {
             case StateRegistry.STATUS_ID:
                 connection.setState(StateRegistry.STATUS);
                 connection.setProtocolVersion(handshake.getProtocolVersion());
-                connection.setSessionHandler(new StatusSessionHandler(connection));
+                connection.setSessionHandler(new StatusSessionHandler(connection, ic));
                 break;
             case StateRegistry.LOGIN_ID:
                 connection.setState(StateRegistry.LOGIN);
@@ -37,12 +59,70 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
                     connection.closeWith(Disconnect.create(TranslatableComponent.of("multiplayer.disconnect.outdated_client")));
                     return;
                 } else {
-                    connection.setSessionHandler(new LoginSessionHandler(connection));
+                    InetAddress address = ((InetSocketAddress) connection.getChannel().remoteAddress()).getAddress();
+                    if (!VelocityServer.getServer().getIpAttemptLimiter().attempt(address)) {
+                        connection.closeWith(Disconnect.create(TextComponent.of("You are logging in too fast, try again later.")));
+                        return;
+                    }
+                    VelocityServer.getServer().getEventManager().fireAndForget(new ConnectionHandshakeEvent(ic));
+                    connection.setSessionHandler(new LoginSessionHandler(connection, ic));
                 }
                 break;
             default:
                 throw new IllegalArgumentException("Invalid state " + handshake.getNextStatus());
         }
+    }
 
+    @Override
+    public void handleUnknown(ByteBuf buf) {
+        throw new IllegalStateException("Unknown data " + ByteBufUtil.hexDump(buf));
+    }
+
+    private void handleLegacy(MinecraftPacket packet) {
+        if (packet instanceof LegacyPing) {
+            VelocityConfiguration configuration = VelocityServer.getServer().getConfiguration();
+            ServerPing ping = new ServerPing(
+                    new ServerPing.Version(ProtocolConstants.MAXIMUM_GENERIC_VERSION, "Velocity " + ProtocolConstants.SUPPORTED_GENERIC_VERSION_STRING),
+                    new ServerPing.Players(VelocityServer.getServer().getPlayerCount(), configuration.getShowMaxPlayers(), ImmutableList.of()),
+                    configuration.getMotdComponent(),
+                    null
+            );
+            ProxyPingEvent event = new ProxyPingEvent(new LegacyInboundConnection(connection), ping);
+            VelocityServer.getServer().getEventManager().fire(event)
+                    .thenRunAsync(() -> {
+                        // The disconnect packet is the same as the server response one.
+                        connection.closeWith(LegacyDisconnect.fromPingResponse(LegacyPingResponse.from(event.getPing())));
+                    }, connection.getChannel().eventLoop());
+        } else if (packet instanceof LegacyHandshake) {
+            connection.closeWith(LegacyDisconnect.from(TextComponent.of("Your client is old, please upgrade!", TextColor.RED)));
+        }
+    }
+
+    private static class LegacyInboundConnection implements InboundConnection {
+        private final MinecraftConnection connection;
+
+        private LegacyInboundConnection(MinecraftConnection connection) {
+            this.connection = connection;
+        }
+
+        @Override
+        public InetSocketAddress getRemoteAddress() {
+            return (InetSocketAddress) connection.getChannel().remoteAddress();
+        }
+
+        @Override
+        public Optional<InetSocketAddress> getVirtualHost() {
+            return Optional.empty();
+        }
+
+        @Override
+        public boolean isActive() {
+            return !connection.isClosed();
+        }
+
+        @Override
+        public int getProtocolVersion() {
+            return 0;
+        }
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/InitialInboundConnection.java

@@ -0,0 +1,38 @@
+package com.velocitypowered.proxy.connection.client;
+
+import com.velocitypowered.api.proxy.InboundConnection;
+import com.velocitypowered.proxy.connection.MinecraftConnection;
+import com.velocitypowered.proxy.protocol.packet.Handshake;
+
+import java.net.InetSocketAddress;
+import java.util.Optional;
+
+class InitialInboundConnection implements InboundConnection {
+    private final MinecraftConnection connection;
+    private final Handshake handshake;
+
+    InitialInboundConnection(MinecraftConnection connection, Handshake handshake) {
+        this.connection = connection;
+        this.handshake = handshake;
+    }
+
+    @Override
+    public InetSocketAddress getRemoteAddress() {
+        return (InetSocketAddress) connection.getChannel().remoteAddress();
+    }
+
+    @Override
+    public Optional<InetSocketAddress> getVirtualHost() {
+        return Optional.of(InetSocketAddress.createUnresolved(handshake.getServerAddress(), handshake.getPort()));
+    }
+
+    @Override
+    public boolean isActive() {
+        return connection.getChannel().isActive();
+    }
+
+    @Override
+    public int getProtocolVersion() {
+        return connection.getProtocolVersion();
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/connection/client/LoginSessionHandler.java

@@ -1,8 +1,15 @@
 package com.velocitypowered.proxy.connection.client;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.event.connection.LoginEvent;
+import com.velocitypowered.api.event.connection.PreLoginEvent;
+import com.velocitypowered.api.event.connection.PreLoginEvent.PreLoginComponentResult;
+import com.velocitypowered.api.event.permission.PermissionsSetupEvent;
+import com.velocitypowered.api.event.player.GameProfileRequestEvent;
+import com.velocitypowered.api.proxy.InboundConnection;
+import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.proxy.connection.VelocityConstants;
-import com.velocitypowered.proxy.data.GameProfile;
+import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
@@ -10,8 +17,9 @@ import com.velocitypowered.proxy.protocol.packet.*;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.api.server.ServerInfo;
 import com.velocitypowered.proxy.util.EncryptionUtils;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
 import net.kyori.text.TextComponent;
 import net.kyori.text.format.TextColor;
@@ -19,6 +27,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
 import java.net.InetSocketAddress;
+import java.net.MalformedURLException;
 import java.net.URL;
 import java.security.GeneralSecurityException;
 import java.security.KeyPair;
@@ -32,80 +41,113 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
             "https://sessionserver.mojang.com/session/minecraft/hasJoined?username=%s&serverId=%s&ip=%s";
     
     private final MinecraftConnection inbound;
+    private final InboundConnection apiInbound;
     private ServerLogin login;
     private byte[] verify;
     private int playerInfoId;
 
-    public LoginSessionHandler(MinecraftConnection inbound) {
+    public LoginSessionHandler(MinecraftConnection inbound, InboundConnection apiInbound) {
         this.inbound = Preconditions.checkNotNull(inbound, "inbound");
+        this.apiInbound = Preconditions.checkNotNull(apiInbound, "apiInbound");
     }
 
     @Override
-    public void activated() {
-        if (inbound.getProtocolVersion() >= ProtocolConstants.MINECRAFT_1_13) {
-            LoginPluginMessage message = new LoginPluginMessage();
-            playerInfoId = ThreadLocalRandom.current().nextInt();
-            message.setId(playerInfoId);
-            message.setChannel(VelocityConstants.VELOCITY_IP_FORWARDING_CHANNEL);
-            message.setData(Unpooled.EMPTY_BUFFER);
-            inbound.write(message);
-        }
-    }
-
-    @Override
-    public void handle(MinecraftPacket packet) throws Exception {
+    public void handle(MinecraftPacket packet) {
         if (packet instanceof LoginPluginResponse) {
             LoginPluginResponse lpr = (LoginPluginResponse) packet;
-            if (lpr.getId() == playerInfoId && lpr.isSuccess()) {
-                // Uh oh, someone's trying to run Velocity behind Velocity. We don't want that happening.
-                inbound.closeWith(Disconnect.create(
-                        TextComponent.of("Running Velocity behind Velocity isn't supported.", TextColor.RED)
-                ));
+            if (lpr.getId() == playerInfoId) {
+                if (lpr.isSuccess()) {
+                    // Uh oh, someone's trying to run Velocity behind Velocity. We don't want that happening.
+                    inbound.closeWith(Disconnect.create(
+                            TextComponent.of("Running Velocity behind Velocity isn't supported.", TextColor.RED)
+                    ));
+                } else {
+                    // Proceed with the regular login process.
+                    beginPreLogin();
+                }
             }
         } else if (packet instanceof ServerLogin) {
             this.login = (ServerLogin) packet;
 
-            if (VelocityServer.getServer().getConfiguration().isOnlineMode()) {
-                // Request encryption.
-                EncryptionRequest request = generateRequest();
-                this.verify = Arrays.copyOf(request.getVerifyToken(), 4);
-                inbound.write(request);
+            if (inbound.getProtocolVersion() >= ProtocolConstants.MINECRAFT_1_13) {
+                LoginPluginMessage message = new LoginPluginMessage();
+                playerInfoId = ThreadLocalRandom.current().nextInt();
+                message.setId(playerInfoId);
+                message.setChannel(VelocityConstants.VELOCITY_IP_FORWARDING_CHANNEL);
+                message.setData(Unpooled.EMPTY_BUFFER);
+                inbound.write(message);
             } else {
-                // Offline-mode, don't try to request encryption.
-                handleSuccessfulLogin(GameProfile.forOfflinePlayer(login.getUsername()));
+                beginPreLogin();
             }
         } else if (packet instanceof EncryptionResponse) {
-            KeyPair serverKeyPair = VelocityServer.getServer().getServerKeyPair();
-            EncryptionResponse response = (EncryptionResponse) packet;
-            byte[] decryptedVerifyToken = EncryptionUtils.decryptRsa(serverKeyPair, response.getVerifyToken());
-            if (!Arrays.equals(verify, decryptedVerifyToken)) {
-                throw new IllegalStateException("Unable to successfully decrypt the verification token.");
+            try {
+                KeyPair serverKeyPair = VelocityServer.getServer().getServerKeyPair();
+                EncryptionResponse response = (EncryptionResponse) packet;
+                byte[] decryptedVerifyToken = EncryptionUtils.decryptRsa(serverKeyPair, response.getVerifyToken());
+                if (!Arrays.equals(verify, decryptedVerifyToken)) {
+                    throw new IllegalStateException("Unable to successfully decrypt the verification token.");
+                }
+
+                byte[] decryptedSharedSecret = EncryptionUtils.decryptRsa(serverKeyPair, response.getSharedSecret());
+                String serverId = EncryptionUtils.generateServerId(decryptedSharedSecret, serverKeyPair.getPublic());
+
+                String playerIp = ((InetSocketAddress) inbound.getChannel().remoteAddress()).getHostString();
+                VelocityServer.getServer().getHttpClient()
+                        .get(new URL(String.format(MOJANG_SERVER_AUTH_URL, login.getUsername(), serverId, playerIp)))
+                        .thenAcceptAsync(profileResponse -> {
+                            if (inbound.isClosed()) {
+                                // The player disconnected after we authenticated them.
+                                return;
+                            }
+                            
+                            try {
+                                inbound.enableEncryption(decryptedSharedSecret);
+                            } catch (GeneralSecurityException e) {
+                                throw new RuntimeException(e);
+                            }
+
+                            initializePlayer(VelocityServer.GSON.fromJson(profileResponse, GameProfile.class), true);
+                        }, inbound.getChannel().eventLoop())
+                        .exceptionally(exception -> {
+                            logger.error("Unable to enable encryption", exception);
+                            inbound.close();
+                            return null;
+                        });
+            } catch (GeneralSecurityException e) {
+                logger.error("Unable to enable encryption", e);
+                inbound.close();
+            } catch (MalformedURLException e) {
+                throw new AssertionError(e);
             }
-
-            byte[] decryptedSharedSecret = EncryptionUtils.decryptRsa(serverKeyPair, response.getSharedSecret());
-            String serverId = EncryptionUtils.generateServerId(decryptedSharedSecret, serverKeyPair.getPublic());
-
-            String playerIp = ((InetSocketAddress) inbound.getChannel().remoteAddress()).getHostString();
-            VelocityServer.getServer().getHttpClient()
-                    .get(new URL(String.format(MOJANG_SERVER_AUTH_URL, login.getUsername(), serverId, playerIp)))
-                    .thenAcceptAsync(profileResponse -> {
-                        try {
-                            inbound.enableEncryption(decryptedSharedSecret);
-                        } catch (GeneralSecurityException e) {
-                            throw new RuntimeException(e);
-                        }
-
-                        GameProfile profile = VelocityServer.GSON.fromJson(profileResponse, GameProfile.class);
-                        handleSuccessfulLogin(profile);
-                    }, inbound.getChannel().eventLoop())
-                    .exceptionally(exception -> {
-                        logger.error("Unable to enable encryption", exception);
-                        inbound.close();
-                        return null;
-                    });
         }
     }
 
+    private void beginPreLogin() {
+        PreLoginEvent event = new PreLoginEvent(apiInbound, login.getUsername());
+        VelocityServer.getServer().getEventManager().fire(event)
+                .thenRunAsync(() -> {
+                    if (inbound.isClosed()) {
+                        // The player was disconnected
+                        return;
+                    }
+                    PreLoginComponentResult result = event.getResult();
+                    if (!result.isAllowed()) {
+                        // The component is guaranteed to be provided if the connection was denied.
+                        inbound.closeWith(Disconnect.create(event.getResult().getReason().get()));
+                        return;
+                    }
+
+                    if (VelocityServer.getServer().getConfiguration().isOnlineMode() || result.isOnlineModeAllowed()) {
+                        // Request encryption.
+                        EncryptionRequest request = generateRequest();
+                        this.verify = Arrays.copyOf(request.getVerifyToken(), 4);
+                        inbound.write(request);
+                    } else {
+                        initializePlayer(GameProfile.forOfflinePlayer(login.getUsername()), false);
+                    }
+                }, inbound.getChannel().eventLoop());
+    }
+
     private EncryptionRequest generateRequest() {
         byte[] verify = new byte[4];
         ThreadLocalRandom.current().nextBytes(verify);
@@ -116,9 +158,40 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
         return request;
     }
 
-    private void handleSuccessfulLogin(GameProfile profile) {
-        // Initiate a regular connection and move over to it.
-        ConnectedPlayer player = new ConnectedPlayer(profile, inbound);
+    private void initializePlayer(GameProfile profile, boolean onlineMode) {
+        GameProfileRequestEvent profileRequestEvent = new GameProfileRequestEvent(apiInbound, profile, onlineMode);
+
+        VelocityServer.getServer().getEventManager().fire(profileRequestEvent).thenCompose(profileEvent -> {
+            // Initiate a regular connection and move over to it.
+            ConnectedPlayer player = new ConnectedPlayer(profileEvent.getGameProfile(), inbound,
+                    apiInbound.getVirtualHost().orElse(null));
+
+            return VelocityServer.getServer().getEventManager().fire(new PermissionsSetupEvent(player, ConnectedPlayer.DEFAULT_PERMISSIONS))
+                        .thenCompose(event -> {
+                            // wait for permissions to load, then set the players permission function
+                            player.setPermissionFunction(event.createFunction(player));
+                            // then call & wait for the login event
+                            return VelocityServer.getServer().getEventManager().fire(new LoginEvent(player));
+                        })
+                        // then complete the connection
+                        .thenAcceptAsync(event -> {
+                            if (inbound.isClosed()) {
+                                // The player was disconnected
+                                return;
+                            }
+                            if (!event.getResult().isAllowed()) {
+                                // The component is guaranteed to be provided if the connection was denied.
+                                inbound.closeWith(Disconnect.create(event.getResult().getReason().get()));
+                                return;
+                            }
+
+                            handleProxyLogin(player);
+                        }, inbound.getChannel().eventLoop());
+        });
+
+    }
+
+    private void handleProxyLogin(ConnectedPlayer player) {
         Optional<ServerInfo> toTry = player.getNextServerToTry();
         if (!toTry.isPresent()) {
             player.close(TextComponent.of("No available servers", TextColor.RED));
@@ -132,14 +205,24 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
         }
 
         ServerLoginSuccess success = new ServerLoginSuccess();
-        success.setUsername(profile.getName());
-        success.setUuid(profile.idAsUuid());
+        success.setUsername(player.getUsername());
+        success.setUuid(player.getUniqueId());
         inbound.write(success);
 
-        logger.info("{} has connected", player);
         inbound.setAssociation(player);
         inbound.setState(StateRegistry.PLAY);
+
+        if (!VelocityServer.getServer().registerConnection(player)) {
+            inbound.closeWith(Disconnect.create(TextComponent.of("You are already on this proxy!", TextColor.RED)));
+        }
+
+        logger.info("{} has connected", player);
         inbound.setSessionHandler(new InitialConnectSessionHandler(player));
         player.createConnectionRequest(toTry.get()).fireAndForget();
     }
+
+    @Override
+    public void handleUnknown(ByteBuf buf) {
+        throw new IllegalStateException("Unknown data " + ByteBufUtil.hexDump(buf));
+    }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/StatusSessionHandler.java

@@ -1,28 +1,34 @@
 package com.velocitypowered.proxy.connection.client;
 
 import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.event.proxy.ProxyPingEvent;
+import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.StatusPing;
 import com.velocitypowered.proxy.protocol.packet.StatusRequest;
 import com.velocitypowered.proxy.protocol.packet.StatusResponse;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
-import com.velocitypowered.proxy.data.ServerPing;
+import com.velocitypowered.api.proxy.server.ServerPing;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 
 public class StatusSessionHandler implements MinecraftSessionHandler {
     private final MinecraftConnection connection;
+    private final InboundConnection inboundWrapper;
 
-    public StatusSessionHandler(MinecraftConnection connection) {
+    public StatusSessionHandler(MinecraftConnection connection, InboundConnection inboundWrapper) {
         this.connection = connection;
+        this.inboundWrapper = inboundWrapper;
     }
 
     @Override
     public void handle(MinecraftPacket packet) {
-        Preconditions.checkArgument(packet instanceof StatusPing|| packet instanceof StatusRequest,
+        Preconditions.checkArgument(packet instanceof StatusPing || packet instanceof StatusRequest,
                 "Unrecognized packet type " + packet.getClass().getName());
 
         if (packet instanceof StatusPing) {
@@ -34,15 +40,22 @@ public class StatusSessionHandler implements MinecraftSessionHandler {
         VelocityConfiguration configuration = VelocityServer.getServer().getConfiguration();
 
         // Status request
-        ServerPing ping = new ServerPing(
-                new ServerPing.Version(connection.getProtocolVersion(), "Velocity 1.9-1.13"),
-                new ServerPing.Players(0, configuration.getShowMaxPlayers()),
+        int shownVersion = ProtocolConstants.isSupported(connection.getProtocolVersion()) ? connection.getProtocolVersion() :
+                ProtocolConstants.MAXIMUM_GENERIC_VERSION;
+        ServerPing initialPing = new ServerPing(
+                new ServerPing.Version(shownVersion, "Velocity " + ProtocolConstants.SUPPORTED_GENERIC_VERSION_STRING),
+                new ServerPing.Players(VelocityServer.getServer().getPlayerCount(), configuration.getShowMaxPlayers(), ImmutableList.of()),
                 configuration.getMotdComponent(),
-                null
+                configuration.getFavicon()
         );
-        StatusResponse response = new StatusResponse();
-        response.setStatus(VelocityServer.GSON.toJson(ping));
-        connection.write(response);
+
+        ProxyPingEvent event = new ProxyPingEvent(inboundWrapper, initialPing);
+        VelocityServer.getServer().getEventManager().fire(event)
+                .thenRunAsync(() -> {
+                    StatusResponse response = new StatusResponse();
+                    response.setStatus(VelocityServer.GSON.toJson(event.getPing()));
+                    connection.write(response);
+                }, connection.getChannel().eventLoop());
     }
 
     @Override

proxy/src/main/java/com/velocitypowered/proxy/connection/util/ConnectionRequestResults.java

@@ -3,6 +3,7 @@ package com.velocitypowered.proxy.connection.util;
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import net.kyori.text.Component;
+import net.kyori.text.TextComponent;
 import net.kyori.text.serializer.ComponentSerializers;
 
 import java.util.Optional;
@@ -42,4 +43,18 @@ public class ConnectionRequestResults {
             }
         };
     }
+
+    public static ConnectionRequestBuilder.Result forDisconnect(TextComponent component) {
+        return new ConnectionRequestBuilder.Result() {
+            @Override
+            public ConnectionRequestBuilder.Status getStatus() {
+                return ConnectionRequestBuilder.Status.SERVER_DISCONNECTED;
+            }
+
+            @Override
+            public Optional<Component> getReason() {
+                return Optional.of(component);
+            }
+        };
+    }
 }

proxy/src/main/java/com/velocitypowered/proxy/console/VelocityConsole.java

@@ -0,0 +1,52 @@
+package com.velocitypowered.proxy.console;
+
+import com.velocitypowered.proxy.VelocityServer;
+import net.kyori.text.TextComponent;
+import net.kyori.text.format.TextColor;
+import net.minecrell.terminalconsole.SimpleTerminalConsole;
+import org.jline.reader.*;
+
+import java.util.List;
+import java.util.Optional;
+
+public final class VelocityConsole extends SimpleTerminalConsole {
+
+    private final VelocityServer server;
+
+    public VelocityConsole(VelocityServer server) {
+        this.server = server;
+    }
+
+    @Override
+    protected LineReader buildReader(LineReaderBuilder builder) {
+        return super.buildReader(builder
+                .appName("Velocity")
+                .completer((reader, parsedLine, list) -> {
+                    Optional<List<String>> o = server.getCommandManager().offerSuggestions(server.getConsoleCommandSource(), parsedLine.line());
+                    o.ifPresent(offers -> {
+                        for (String offer : offers) {
+                            list.add(new Candidate(offer));
+                        }
+                    });
+                })
+        );
+    }
+
+    @Override
+    protected boolean isRunning() {
+        return !this.server.isShutdown();
+    }
+
+    @Override
+    protected void runCommand(String command) {
+        if (!this.server.getCommandManager().execute(this.server.getConsoleCommandSource(), command)) {
+            server.getConsoleCommandSource().sendMessage(TextComponent.of("Command not found.", TextColor.RED));
+        }
+    }
+
+    @Override
+    protected void shutdown() {
+        this.server.shutdown();
+    }
+
+}