Inter server teleporting is there, albeit slightly borked

src/main/java/net/md_5/bungee/BungeeCord.java

@@ -14,7 +14,9 @@ import java.util.concurrent.Executors;
 import static net.md_5.bungee.Logger.$;
 import net.md_5.bungee.command.Command;
 import net.md_5.bungee.command.CommandEnd;
+import net.md_5.bungee.command.CommandList;
 import net.md_5.bungee.command.CommandSender;
+import net.md_5.bungee.command.CommandServer;
 import net.md_5.bungee.command.ConsoleCommandSender;
 
 public class BungeeCord {
@@ -58,6 +60,8 @@ public class BungeeCord {
 
     {
         commandMap.put("end", new CommandEnd());
+        commandMap.put("glist", new CommandList());
+        commandMap.put("server", new CommandServer());
     }
 
     public static void main(String[] args) throws IOException {

src/main/java/net/md_5/bungee/Configuration.java

@@ -194,10 +194,11 @@ public class Configuration {
 
     public InetSocketAddress getServer(String name) {
         String hostline = (name == null) ? defaultServerName : name;
-        if (hostline != null) {
+        String server = servers.get(hostline);
-            return Util.getAddr(hostline);
+        if (server != null) {
+            return Util.getAddr(server);
         } else {
-            throw new IllegalArgumentException("No server by name " + name);
+            return Util.getAddr(servers.get(defaultServerName));
         }
     }
 

src/main/java/net/md_5/bungee/EntityMap.java

@@ -0,0 +1,61 @@
+package net.md_5.bungee;
+
+public class EntityMap {
+
+    public final static int[][] entityIds = new int[256][];
+
+    static {
+        entityIds[0x05] = new int[]{1};
+        entityIds[0x07] = new int[]{1, 5};
+        entityIds[0x11] = new int[]{1};
+        entityIds[0x12] = new int[]{1};
+        entityIds[0x13] = new int[]{1};
+        entityIds[0x14] = new int[]{1};
+        entityIds[0x15] = new int[]{1};
+        entityIds[0x16] = new int[]{1, 5};
+        entityIds[0x17] = new int[]{1};
+        entityIds[0x18] = new int[]{1};
+        entityIds[0x19] = new int[]{1};
+        entityIds[0x1C] = new int[]{1};
+        entityIds[0x1E] = new int[]{1};
+        entityIds[0x1F] = new int[]{1};
+        entityIds[0x20] = new int[]{1};
+        entityIds[0x21] = new int[]{1};
+        entityIds[0x22] = new int[]{1};
+        entityIds[0x26] = new int[]{1};
+        entityIds[0x27] = new int[]{1, 5};
+        entityIds[0x28] = new int[]{1};
+        entityIds[0x47] = new int[]{1};
+    }
+
+    public static void rewrite(byte[] packet, int oldId, int newId) {
+        int packetId = Util.getId(packet);
+        if (packetId == 0x1D) { // bulk entity
+            for (int pos = 2; pos < packet.length; pos += 4) {
+                if (oldId == readInt(packet, pos)) {
+                    setInt(packet, pos, newId);
+                }
+            }
+        } else {
+            int[] idArray = entityIds[packetId];
+            if (idArray != null) {
+                for (int pos : idArray) {
+                    if (oldId == readInt(packet, pos)) {
+                        setInt(packet, pos, newId);
+                    }
+                }
+            }
+        }
+    }
+
+    private static void setInt(byte[] buf, int pos, int i) {
+        buf[pos] = (byte) (i >> 24);
+        buf[pos + 1] = (byte) (i >> 16);
+        buf[pos + 2] = (byte) (i >> 8);
+        buf[pos + 3] = (byte) i;
+    }
+
+    private static int readInt(byte[] buf, int pos) {
+        return (((buf[pos] & 0xFF) << 24) | ((buf[pos + 1] & 0xFF) << 16) | ((buf[pos + 2] & 0xFF) << 8) | buf[pos + 3] & 0xFF);
+    }
+}

src/main/java/net/md_5/bungee/UserConnection.java

@@ -6,18 +6,28 @@ import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
+import net.md_5.bungee.command.CommandSender;
 import net.md_5.bungee.packet.DefinedPacket;
+import net.md_5.bungee.packet.Packet10HeldItem;
+import net.md_5.bungee.packet.Packet1Login;
 import net.md_5.bungee.packet.Packet2Handshake;
 import net.md_5.bungee.packet.Packet3Chat;
+import net.md_5.bungee.packet.Packet46GameState;
+import net.md_5.bungee.packet.Packet9Respawn;
+import net.md_5.bungee.packet.PacketFAPluginMessage;
 import net.md_5.bungee.packet.PacketInputStream;
 
-public class UserConnection extends GenericConnection {
+public class UserConnection extends GenericConnection implements CommandSender {
 
     public final Packet2Handshake handshake;
     public Queue<DefinedPacket> packetQueue = new ConcurrentLinkedQueue<>();
     private ServerConnection server;
     private UpstreamBridge upBridge;
     private DownstreamBridge downBridge;
+    // reconnect stuff
+    private Packet10HeldItem heldItem;
+    private int clientEntityId;
+    private int serverEntityId;
 
     public UserConnection(Socket socket, PacketInputStream in, OutputStream out, Packet2Handshake handshake) {
         super(socket, in, out);
@@ -25,16 +35,37 @@ public class UserConnection extends GenericConnection {
         username = handshake.username;
     }
 
+    public void connect(String server) {
+        InetSocketAddress addr = BungeeCord.instance.config.getServer(server);
+        if (addr == null) {
+            sendMessage(ChatColor.RED + "Specified server does not exist");
+            return;
+        }
+        connect(addr);
+    }
+
     public void connect(InetSocketAddress serverAddr) {
         try {
             ServerConnection newServer = ServerConnection.connect(serverAddr, handshake, true);
+            if (downBridge != null) {
+                downBridge.interrupt();
+            }
             if (server == null) {
+                clientEntityId = newServer.loginPacket.entityId;
                 out.write(newServer.loginPacket.getPacket());
                 upBridge = new UpstreamBridge();
                 upBridge.start();
+            } else {
+                server.disconnect("Quitting");
+                out.write(new Packet9Respawn((byte) 1, (byte) 0, (byte) 0, (short) 256, "DEFAULT").getPacket());
+                out.write(new Packet9Respawn((byte) -1, (byte) 0, (byte) 0, (short) 256, "DEFAULT").getPacket());
+                out.write(new Packet46GameState((byte) 2, (byte) 0).getPacket());
+                Packet1Login login = newServer.loginPacket;
+                serverEntityId = login.entityId;
+                out.write(new Packet9Respawn(login.dimension, login.difficulty, login.gameMode, (short) 256, login.levelType).getPacket());
+                if (heldItem != null) {
+                    newServer.out.write(heldItem.getPacket());
                 }
-            if (downBridge != null) {
-                downBridge.interrupt();
             }
             downBridge = new DownstreamBridge();
             server = newServer;
@@ -70,6 +101,11 @@ public class UserConnection extends GenericConnection {
         }
     }
 
+    @Override
+    public void sendMessage(String message) {
+        packetQueue.add(new Packet3Chat(message));
+    }
+
     private class UpstreamBridge extends Thread {
 
         public UpstreamBridge() {
@@ -81,7 +117,23 @@ public class UserConnection extends GenericConnection {
             while (!interrupted()) {
                 try {
                     byte[] packet = in.readPacket();
+                    boolean sendPacket = true;
+
+                    int id = Util.getId(packet);
+                    if (id == 0x03) {
+                        Packet3Chat chat = new Packet3Chat(packet);
+                        String message = chat.message;
+                        if (message.startsWith("/")) {
+                            sendPacket = !BungeeCord.instance.dispatchCommand(message.substring(1), UserConnection.this);
+                        }
+                    } else if (id == 0x10) {
+                        heldItem = new Packet10HeldItem(packet);
+                    }
+
+                    EntityMap.rewrite(packet, clientEntityId, serverEntityId);
+                    if (sendPacket && !server.socket.isClosed()) {
                         server.out.write(packet);
+                    }
                 } catch (IOException ex) {
                     destory("Reached end of stream");
                 } catch (Exception ex) {
@@ -102,10 +154,30 @@ public class UserConnection extends GenericConnection {
             while (!interrupted()) {
                 try {
                     byte[] packet = server.in.readPacket();
+                    boolean sendPacket = true;
+
+                    int id = Util.getId(packet);
+                    if (id == 0xFA) {
+                        PacketFAPluginMessage message = new PacketFAPluginMessage(packet);
+                        if (message.tag.equals("RubberBand")) {
+                            String server = new String(message.data);
+                            connect(server);
+                            sendPacket = false;
+                        }
+                    }
+
+                    while (!packetQueue.isEmpty()) {
+                        DefinedPacket p = packetQueue.poll();
+                        if (p != null) {
+                            out.write(p.getPacket());
+                        }
+                    }
+
+                    EntityMap.rewrite(packet, serverEntityId, clientEntityId);
+                    if (sendPacket) {
                         out.write(packet);
-                    out.flush();
+                    }
                 } catch (IOException ex) {
-                    destory("Reached end of stream");
                 } catch (Exception ex) {
                     destory(Util.exception(ex));
                 }

src/main/java/net/md_5/bungee/command/CommandList.java

@@ -0,0 +1,24 @@
+package net.md_5.bungee.command;
+
+import java.util.Collection;
+import net.md_5.bungee.BungeeCord;
+import net.md_5.bungee.ChatColor;
+import net.md_5.bungee.UserConnection;
+
+public class CommandList extends Command {
+
+    @Override
+    public void execute(CommandSender sender, String[] args) {
+        StringBuilder users = new StringBuilder();
+        Collection<UserConnection> connections = BungeeCord.instance.connections.values();
+
+        for (UserConnection con : connections) {
+            users.append(con.username);
+            users.append(ChatColor.RESET.toString());
+            users.append(", ");
+        }
+
+        users.setLength(users.length() - 2);
+        sender.sendMessage(ChatColor.BLUE + "Currently online across all servers (" + connections.size() + "): " + ChatColor.RESET + users);
+    }
+}

src/main/java/net/md_5/bungee/command/CommandServer.java

@@ -0,0 +1,30 @@
+package net.md_5.bungee.command;
+
+import java.util.Collection;
+import net.md_5.bungee.BungeeCord;
+import net.md_5.bungee.ChatColor;
+import net.md_5.bungee.UserConnection;
+
+public class CommandServer extends Command {
+
+    @Override
+    public void execute(CommandSender sender, String[] args) {
+        if (!(sender instanceof UserConnection)) {
+            return;
+        }
+        UserConnection con = (UserConnection) sender;
+        if (args.length <= 0) {
+            Collection<String> servers = BungeeCord.instance.config.servers.keySet();
+            StringBuilder serverList = new StringBuilder();
+            for (String server : servers) {
+                serverList.append(server);
+                serverList.append(", ");
+            }
+            serverList.setLength(serverList.length() - 2);
+            con.sendMessage(ChatColor.GOLD + "You may connect to the following servers at this time: " + serverList.toString());
+        } else {
+            String server = args[0];
+            con.connect(server);
+        }
+    }
+}