Add a basic command handling framework inspired by Bukkit/BungeeCord.

This doesn't yet support tab complete, that will come later. Additionally,
a /server command (using your configuration) and /velocity (shows basic
copyright information about the proxy) have been added.

README.md

@@ -23,6 +23,15 @@ 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:

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

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

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

@@ -0,0 +1,23 @@
+package com.velocitypowered.api.command;
+
+import net.kyori.text.Component;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Represents something that can be used to run a {@link CommandExecutor}.
+ */
+public interface CommandInvoker {
+    /**
+     * Sends the specified {@code component} to the invoker.
+     * @param component the text component to send
+     */
+    void sendMessage(@Nonnull Component component);
+
+    /**
+     * Determines whether or not the invoker has a particular permission.
+     * @param permission the permission to check for
+     * @return whether or not the invoker has permission to run this command
+     */
+    boolean hasPermission(@Nonnull String permission);
+}

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

@@ -0,0 +1,26 @@
+package com.velocitypowered.api.proxy;
+
+import java.net.InetSocketAddress;
+
+/**
+ * Represents a connection to the proxy. There is no guarantee that the connection has been fully initialized.
+ */
+public interface InboundConnection {
+    /**
+     * 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();
+
+    /**
+     * 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 +1,18 @@
 package com.velocitypowered.api.proxy;
 
+import com.velocitypowered.api.command.CommandInvoker;
 import com.velocitypowered.api.server.ServerInfo;
 import com.velocitypowered.api.util.MessagePosition;
 import net.kyori.text.Component;
 
 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 CommandInvoker, InboundConnection {
     /**
      * Returns the player's current username.
      * @return the username
@@ -31,18 +31,6 @@ public interface Player {
      */
     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();
-
     /**
      * Sends a chat message to the player's client.
      * @param component the chat message to send

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

@@ -1,5 +1,6 @@
 package com.velocitypowered.api.proxy;
 
+import com.velocitypowered.api.command.CommandInvoker;
 import com.velocitypowered.api.server.ServerInfo;
 
 import javax.annotation.Nonnull;
@@ -62,4 +63,12 @@ public interface ProxyServer {
      * @param server the server to unregister
      */
     void unregisterServer(@Nonnull ServerInfo server);
+
+    /**
+     * Returns an instance of {@link CommandInvoker} 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 CommandInvoker} instead of using the console invoker.
+     * @return the console command invoker
+     */
+    CommandInvoker getConsoleCommandInvoker();
 }

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

@@ -4,19 +4,24 @@ 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.api.command.CommandInvoker;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ProxyServer;
 import com.velocitypowered.natives.util.Natives;
 import com.velocitypowered.network.ConnectionManager;
+import com.velocitypowered.proxy.command.ServerCommand;
+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.CommandManager;
 import com.velocitypowered.proxy.util.AddressUtil;
 import com.velocitypowered.proxy.util.EncryptionUtils;
 import com.velocitypowered.proxy.util.ServerMap;
 import io.netty.bootstrap.Bootstrap;
 import net.kyori.text.Component;
+import net.kyori.text.serializer.ComponentSerializers;
 import net.kyori.text.serializer.GsonComponentSerializer;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -43,11 +48,26 @@ public class VelocityServer implements ProxyServer {
     private NettyHttpClient httpClient;
     private KeyPair serverKeyPair;
     private final ServerMap servers = new ServerMap();
+    private final CommandManager commandManager = new CommandManager();
 
     private final Map<UUID, ConnectedPlayer> connectionsByUuid = new ConcurrentHashMap<>();
     private final Map<String, ConnectedPlayer> connectionsByName = new ConcurrentHashMap<>();
+    private final CommandInvoker consoleCommandInvoker = new CommandInvoker() {
+        @Override
+        public void sendMessage(@Nonnull Component component) {
+            // TODO: TerminalConsoleAppender
+            logger.info(ComponentSerializers.PLAIN.serialize(component));
+        }
+
+        @Override
+        public boolean hasPermission(@Nonnull String permission) {
+            return true;
+        }
+    };
 
     private VelocityServer() {
+        commandManager.registerCommand("velocity", new VelocityCommand());
+        commandManager.registerCommand("server", new ServerCommand());
     }
 
     public static VelocityServer getServer() {
@@ -62,6 +82,10 @@ public class VelocityServer implements ProxyServer {
         return configuration;
     }
 
+    public CommandManager getCommandManager() {
+        return commandManager;
+    }
+
     public void start() {
         logger.info("Using {}", Natives.compressor.getLoadedVariant());
         logger.info("Using {}", Natives.cipher.getLoadedVariant());
@@ -177,4 +201,9 @@ public class VelocityServer implements ProxyServer {
     public void unregisterServer(@Nonnull ServerInfo server) {
         servers.unregister(server);
     }
+
+    @Override
+    public CommandInvoker getConsoleCommandInvoker() {
+        return consoleCommandInvoker;
+    }
 }

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

@@ -0,0 +1,48 @@
+package com.velocitypowered.proxy.command;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.command.CommandExecutor;
+import com.velocitypowered.api.command.CommandInvoker;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
+public class CommandManager {
+    private final Map<String, CommandExecutor> executors = new HashMap<>();
+
+    public void registerCommand(String name, CommandExecutor executor) {
+        Preconditions.checkNotNull(name, "name");
+        Preconditions.checkNotNull(executor, "executor");
+        this.executors.put(name, executor);
+    }
+
+    public void unregisterCommand(String name) {
+        Preconditions.checkNotNull(name, "name");
+        this.executors.remove(name);
+    }
+
+    public boolean execute(CommandInvoker invoker, String cmdLine) {
+        Preconditions.checkNotNull(invoker, "invoker");
+        Preconditions.checkNotNull(cmdLine, "cmdLine");
+
+        String[] split = cmdLine.split(" ", -1);
+        if (split.length == 0) {
+            return false;
+        }
+
+        String command = split[0];
+        String[] actualArgs = Arrays.copyOfRange(split, 1, split.length);
+        CommandExecutor executor = executors.get(command);
+        if (executor == null) {
+            return false;
+        }
+
+        try {
+            executor.execute(invoker, actualArgs);
+            return true;
+        } catch (Exception e) {
+            throw new RuntimeException("Unable to invoke command " + cmdLine + " for " + invoker, e);
+        }
+    }
+}

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

@@ -0,0 +1,41 @@
+package com.velocitypowered.proxy.command;
+
+import com.velocitypowered.api.command.CommandExecutor;
+import com.velocitypowered.api.command.CommandInvoker;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.proxy.VelocityServer;
+import net.kyori.text.TextComponent;
+import net.kyori.text.format.TextColor;
+
+import javax.annotation.Nonnull;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+public class ServerCommand implements CommandExecutor {
+    @Override
+    public void execute(@Nonnull CommandInvoker invoker, @Nonnull String[] args) {
+        if (!(invoker instanceof Player)) {
+            invoker.sendMessage(TextComponent.of("Only players may run this command.", TextColor.RED));
+            return;
+        }
+
+        Player player = (Player) invoker;
+        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));
+        }
+    }
+}

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

@@ -0,0 +1,42 @@
+package com.velocitypowered.proxy.command;
+
+import com.velocitypowered.api.command.CommandExecutor;
+import com.velocitypowered.api.command.CommandInvoker;
+import com.velocitypowered.proxy.VelocityServer;
+import net.kyori.text.TextComponent;
+import net.kyori.text.event.ClickEvent;
+import net.kyori.text.format.TextColor;
+
+import javax.annotation.Nonnull;
+
+public class VelocityCommand implements CommandExecutor {
+    @Override
+    public void execute(@Nonnull CommandInvoker invoker, @Nonnull 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.", TextColor.WHITE))
+                .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 ", TextColor.WHITE))
+                .append(TextComponent.builder("Velocity GitHub")
+                        .color(TextColor.GREEN)
+                        .clickEvent(new ClickEvent(ClickEvent.Action.OPEN_URL, "https://github.com/astei/velocity"))
+                        .build())
+                .build();
+
+        invoker.sendMessage(thisIsVelocity);
+        invoker.sendMessage(velocityInfo);
+        invoker.sendMessage(velocityWebsite);
+    }
+}

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

@@ -1,7 +1,7 @@
 package com.velocitypowered.proxy.connection.client;
 
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.proxy.connection.backend.ServerConnection;
+import com.velocitypowered.proxy.command.VelocityCommand;
 import com.velocitypowered.api.server.ServerInfo;
 import com.velocitypowered.proxy.data.scoreboard.Objective;
 import com.velocitypowered.proxy.data.scoreboard.Score;
@@ -9,16 +9,13 @@ 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;
@@ -81,11 +78,21 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
         if (packet instanceof Chat) {
             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(msg);
+                    }
+                } 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 PluginMessage) {

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

@@ -83,6 +83,11 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         return connection.getChannel().isActive();
     }
 
+    @Override
+    public int getProtocolVersion() {
+        return connection.getProtocolVersion();
+    }
+
     @Override
     public void sendMessage(@Nonnull Component component, @Nonnull MessagePosition position) {
         Preconditions.checkNotNull(component, "component");
@@ -217,6 +222,11 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
         return "[connected player] " + getProfile().getName() + " (" + getRemoteAddress() + ")";
     }
 
+    @Override
+    public boolean hasPermission(@Nonnull String permission) {
+        return false; // TODO: Implement permissions.
+    }
+
     private class ConnectionRequestBuilderImpl implements ConnectionRequestBuilder {
         private final ServerInfo info;
 

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

@@ -1,6 +1,7 @@
 package com.velocitypowered.proxy.connection.client;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
@@ -14,6 +15,8 @@ import net.kyori.text.TextComponent;
 import net.kyori.text.TranslatableComponent;
 import net.kyori.text.format.TextColor;
 
+import java.net.InetSocketAddress;
+
 public class HandshakeSessionHandler implements MinecraftSessionHandler {
     private final MinecraftConnection connection;
 
@@ -70,4 +73,27 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
             connection.closeWith(LegacyDisconnect.from(TextComponent.of("Your client is old, please upgrade!", TextColor.RED)));
         }
     }
+
+    private static class InitialInboundConnection implements InboundConnection {
+        private final MinecraftConnection connection;
+
+        private InitialInboundConnection(MinecraftConnection connection) {
+            this.connection = connection;
+        }
+
+        @Override
+        public InetSocketAddress getRemoteAddress() {
+            return (InetSocketAddress) connection.getChannel().remoteAddress();
+        }
+
+        @Override
+        public boolean isActive() {
+            return connection.getChannel().isActive();
+        }
+
+        @Override
+        public int getProtocolVersion() {
+            return connection.getProtocolVersion();
+        }
+    }
 }