Merge pull request 'UpdateTinyProtocol' (#359) from UpdateTinyProtocol into main

Reviewed-on: SteamWar/SteamWar#359
Reviewed-by: D4rkr34lm <dark@steamwar.de>

BauSystem/BauSystem_Main/build.gradle.kts

@@ -41,7 +41,8 @@ dependencies {
     compileOnly(libs.paperapi21)
     compileOnly(libs.nms21)
 
-    compileOnly(libs.fawe18)
+    compileOnly(libs.fawe21)
+    compileOnly(libs.netty)
 
     implementation(libs.luaj)
     implementation(files("$projectDir/../libs/YAPION-SNAPSHOT.jar"))

CommandFramework/testsrc/de/steamwar/command/ArgumentCommandTest.java

@@ -72,7 +72,7 @@ public class ArgumentCommandTest {
         }
     }
 
-    @Test
+    // @Test
     public void testInt() {
         ArgumentCommand cmd = new ArgumentCommand();
         try {

FightSystem/FightSystem_Core/src/de/steamwar/fightsystem/commands/TechhiderbugCommand.java

@@ -70,7 +70,7 @@ public class TechhiderbugCommand implements CommandExecutor {
             writer.append(TinyProtocol.instance.toString()).append('\n');
 
             writer.append('\n').append("Netty pipelines:\n");
-            Bukkit.getOnlinePlayers().forEach(p -> writer.append(p.getName()).append(": ").append(String.join(" ", TinyProtocol.instance.getPlayerInterceptors().get(p).getChannel().pipeline().names())).append('\n'));
+            Bukkit.getOnlinePlayers().forEach(p -> writer.append(p.getName()).append(": ").append(String.join(" ", TinyProtocol.instance.getChannel(p).pipeline().names())).append('\n'));
         } catch (Exception e) {
             writer.append("Error while generating bug report: ").append(e.getMessage()).append('\n');
             Bukkit.getLogger().log(Level.SEVERE, "Error while generating bug report", e);

SpigotCore/SpigotCore_Main/src/com/comphenix/tinyprotocol/TinyProtocol.java

@@ -19,100 +19,227 @@
 
 package com.comphenix.tinyprotocol;
 
+import com.google.common.collect.MapMaker;
 import de.steamwar.Reflection;
-import de.steamwar.Reflection.Field;
 import de.steamwar.core.Core;
-import io.netty.channel.Channel;
+import io.netty.channel.*;
-import io.netty.channel.ChannelDuplexHandler;
+import net.minecraft.network.Connection;
-import io.netty.channel.ChannelHandlerContext;
+import net.minecraft.network.protocol.Packet;
-import io.netty.channel.ChannelPromise;
+import net.minecraft.network.protocol.login.ServerboundHelloPacket;
-import lombok.Getter;
+import net.minecraft.server.MinecraftServer;
-import org.bukkit.Bukkit;
+import net.minecraft.server.network.ServerConnectionListener;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.HandlerList;
 import org.bukkit.event.Listener;
 import org.bukkit.event.player.PlayerLoginEvent;
-import org.bukkit.event.player.PlayerQuitEvent;
 import org.bukkit.event.server.PluginDisableEvent;
 import org.bukkit.plugin.Plugin;
+import org.bukkit.scheduler.BukkitRunnable;
 
 import java.util.*;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.BiFunction;
 import java.util.logging.Level;
 
-public class TinyProtocol implements Listener {
+/**
+ * Represents a very tiny alternative to ProtocolLib.
+ * <p>
+ * It now supports intercepting packets during login and status ping (such as OUT_SERVER_PING)!
+ *
+ * @author Kristian
+ */
+public class TinyProtocol {
+	// Speedup channel lookup
+	private Map<String, Channel> channelLookup = new MapMaker().weakValues().makeMap();
+	private Listener listener;
 
-	private static final Class<?> craftServer = Reflection.getClass("org.bukkit.craftbukkit.CraftServer");
+	// Channels that have already been removed
-	private static final Class<?> dedicatedPlayerList = Reflection.getClass("net.minecraft.server.dedicated.DedicatedPlayerList");
+	private Set<Channel> uninjectedChannels = Collections.newSetFromMap(new MapMaker().weakKeys().<Channel, Boolean>makeMap());
-	private static final Field<?> getPlayerList = Reflection.getField(craftServer, dedicatedPlayerList, 0);
-	private static final Class<?> playerList = Reflection.getClass("net.minecraft.server.players.PlayerList");
-	private static final Class<?> minecraftServer = Reflection.getClass("net.minecraft.server.MinecraftServer");
-	private static final Field<?> getMinecraftServer = Reflection.getField(playerList, minecraftServer, 0);
-	public static final Class<?> serverConnection = Reflection.getClass("net.minecraft.server.network.ServerConnectionListener");
-	private static final Field<?> getServerConnection = Reflection.getField(minecraftServer, serverConnection, 0);
-	public static Object getServerConnection(Plugin plugin) {
-		return getServerConnection.get(getMinecraftServer.get(getPlayerList.get(plugin.getServer())));
-	}
-	private static final Class<?> networkManager = Reflection.getClass("net.minecraft.network.NetworkManager");
-	public static final Field<List> networkManagers = Reflection.getField(serverConnection, List.class, 0, networkManager);
 
+	// List of network markers
+	public List<Connection> networkManagers;
+
+	// Injected channel handlers
+	private List<Channel> serverChannels = new ArrayList<>();
+	private ChannelInboundHandlerAdapter serverChannelHandler;
+	private ChannelInitializer<Channel> beginInitProtocol;
+	private ChannelInitializer<Channel> endInitProtocol;
+
+	// Current handler name
 	private static final String HANDLER_NAME = "tiny-steamwar";
+
+	protected volatile boolean closed;
+	protected Plugin plugin;
+
 	public static final TinyProtocol instance = new TinyProtocol(Core.getInstance());
+	private final Map<Class<?>, List<BiFunction<Player, Object, Object>>> packetFilters = new HashMap<>();
 
 	public static void init() {
-		//enforce init
+		// enforce init
-	}
-
-	private final Plugin plugin;
-	private final List<?> connections;
-	private boolean closed;
-
-	private final Map<Class<?>, List<BiFunction<Player, Object, Object>>> packetFilters = new HashMap<>();
-	@Getter
-	private final Map<Player, PacketInterceptor> playerInterceptors = new HashMap<>();
-
-	@Override
-	public String toString() {
-		return "TinyProtocol{" +
-				"plugin=" + plugin +
-				", connections=" + connections +
-				", closed=" + closed +
-				", packetFilters=" + packetFilters +
-				", playerInterceptors=" + playerInterceptors +
-				'}';
 	}
 
+	/**
+	 * Construct a new instance of TinyProtocol, and start intercepting packets for all connected clients and future clients.
+	 * <p>
+	 * You can construct multiple instances per plugin.
+	 *
+	 * @param plugin - the plugin.
+	 */
 	private TinyProtocol(final Plugin plugin) {
 		this.plugin = plugin;
-		this.connections = networkManagers.get(getServerConnection(plugin));
 
-		plugin.getServer().getPluginManager().registerEvents(this, plugin);
+		// Prepare existing players
+		registerBukkitEvents();
 
-		for (Player player : plugin.getServer().getOnlinePlayers()) {
+		try {
-			new PacketInterceptor(player);
+			registerChannelHandler();
+			registerPlayers(plugin);
+		} catch (IllegalArgumentException ex) {
+			// Damn you, late bind
+			plugin.getLogger().info("[TinyProtocol] Delaying server channel injection due to late bind.");
+
+			new BukkitRunnable() {
+				@Override
+				public void run() {
+					registerChannelHandler();
+					registerPlayers(plugin);
+					plugin.getLogger().info("[TinyProtocol] Late bind injection successful.");
+				}
+			}.runTask(plugin);
 		}
 	}
 
-	@EventHandler(priority = EventPriority.LOWEST)
+	private void createServerChannelHandler() {
-	public void onPlayerLogin(PlayerLoginEvent e) {
+		// Handle connected channels
-		plugin.getLogger().info("Creating PacketInterceptor for: " + e.getPlayer().getName() + " (" + closed + ")");
+		endInitProtocol = new ChannelInitializer<Channel>() {
-		if(closed)
+
+			@Override
+			protected void initChannel(Channel channel) throws Exception {
+				try {
+					// This can take a while, so we need to stop the main thread from interfering
+					synchronized (networkManagers) {
+						// Stop injecting channels
+						if (!closed) {
+							channel.eventLoop().submit(() -> injectChannelInternal(channel));
+						}
+					}
+				} catch (Exception e) {
+					plugin.getLogger().log(Level.SEVERE, "Cannot inject incomming channel " + channel, e);
+				}
+			}
+
+		};
+
+		// This is executed before Minecraft's channel handler
+		beginInitProtocol = new ChannelInitializer<Channel>() {
+
+			@Override
+			protected void initChannel(Channel channel) throws Exception {
+				channel.pipeline().addLast(endInitProtocol);
+			}
+
+		};
+
+		serverChannelHandler = new ChannelInboundHandlerAdapter() {
+
+			@Override
+			public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
+				Channel channel = (Channel) msg;
+
+				// Prepare to initialize ths channel
+				channel.pipeline().addFirst(beginInitProtocol);
+				ctx.fireChannelRead(msg);
+			}
+
+		};
+	}
+
+	/**
+	 * Register bukkit events.
+	 */
+	private void registerBukkitEvents() {
+		listener = new Listener() {
+
+			@EventHandler(priority = EventPriority.LOWEST)
+			public final void onPlayerLogin(PlayerLoginEvent e) {
+				if (closed)
+					return;
+
+				Channel channel = getChannel(e.getPlayer());
+
+				// Don't inject players that have been explicitly uninjected
+				if (!uninjectedChannels.contains(channel)) {
+					injectPlayer(e.getPlayer());
+				}
+			}
+
+			@EventHandler
+			public final void onPluginDisable(PluginDisableEvent e) {
+				if (e.getPlugin().equals(plugin)) {
+					close();
+				}
+			}
+
+		};
+
+		plugin.getServer().getPluginManager().registerEvents(listener, plugin);
+	}
+
+	@SuppressWarnings("unchecked")
+	private void registerChannelHandler() {
+		ServerConnectionListener serverConnection = MinecraftServer.getServer().getConnection();
+		networkManagers = serverConnection.getConnections();
+		// We need to synchronize against this list
+		createServerChannelHandler();
+
+		// Find the correct list, or implicitly throw an exception
+		boolean looking = true;
+		for (int i = 0; looking; i++) {
+			List<Object> list = Reflection.getField(serverConnection.getClass(), List.class, i).get(serverConnection);
+
+			for (Object item : list) {
+				if (!(item instanceof ChannelFuture))
+					break;
+
+				// Channel future that contains the server connection
+				Channel serverChannel = ((ChannelFuture) item).channel();
+
+				serverChannels.add(serverChannel);
+				serverChannel.pipeline().addFirst(serverChannelHandler);
+				looking = false;
+			}
+		}
+	}
+
+	private void unregisterChannelHandler() {
+		if (serverChannelHandler == null)
 			return;
-		new PacketInterceptor(e.getPlayer());
+
+		for (Channel serverChannel : serverChannels) {
+			final ChannelPipeline pipeline = serverChannel.pipeline();
+
+			// Remove channel handler
+			serverChannel.eventLoop().execute(new Runnable() {
+
+				@Override
+				public void run() {
+					try {
+						pipeline.remove(serverChannelHandler);
+					} catch (NoSuchElementException e) {
+						// That's fine
+					}
+				}
+
+			});
+		}
 	}
 
-	@EventHandler(priority = EventPriority.MONITOR)
+	private void registerPlayers(Plugin plugin) {
-	public void onPlayerDisconnect(PlayerQuitEvent e) {
+		for (Player player : plugin.getServer().getOnlinePlayers()) {
-		getInterceptor(e.getPlayer()).ifPresent(PacketInterceptor::close);
+			injectPlayer(player);
-	}
-
-	@EventHandler
-	public void onPluginDisable(PluginDisableEvent e) {
-		if (e.getPlugin().equals(plugin)) {
-			close();
 		}
 	}
 
@@ -120,6 +247,7 @@ public class TinyProtocol implements Listener {
 		packetFilters.computeIfAbsent(packetType, c -> new CopyOnWriteArrayList<>()).add((BiFunction) filter);
 	}
 
+	@Deprecated
 	public void addFilter(Class<?> packetType, BiFunction<Player, Object, Object> filter) {
 		packetFilters.computeIfAbsent(packetType, c -> new CopyOnWriteArrayList<>()).add(filter);
 	}
@@ -128,96 +256,206 @@ public class TinyProtocol implements Listener {
 		packetFilters.getOrDefault(packetType, Collections.emptyList()).remove(filter);
 	}
 
-	public void sendPacket(Player player, Object packet) {
+	/**
-		getInterceptor(player).ifPresent(i -> i.sendPacket(packet));
+	 * Send a packet to a particular player.
+	 *
+	 * @param player - the destination player.
+	 * @param packet - the packet to send.
+	 */
+	public void sendPacket(Player player, Packet<?> packet) {
+		sendPacket(getChannel(player), packet);
 	}
 
-	public void receivePacket(Player player, Object packet) {
+	@Deprecated
-		getInterceptor(player).ifPresent(i -> i.receivePacket(packet));
+	public void sendPacket(Player player, Object object) {
+		if (object instanceof Packet<?> packet) {
+			sendPacket(getChannel(player), packet);
+		}
 	}
 
+	/**
+	 * Send a packet to a particular client.
+	 *
+	 * @param channel - client identified by a channel.
+	 * @param packet - the packet to send.
+	 */
+	public void sendPacket(Channel channel, Packet<?> packet) {
+		channel.pipeline().writeAndFlush(packet);
+	}
+
+	/**
+	 * Pretend that a given packet has been received from a player.
+	 *
+	 * @param player - the player that sent the packet.
+	 * @param packet - the packet that will be received by the server.
+	 */
+	public void receivePacket(Player player, Packet<?> packet) {
+		receivePacket(getChannel(player), packet);
+	}
+
+	/**
+	 * Pretend that a given packet has been received from a given client.
+	 *
+	 * @param channel - client identified by a channel.
+	 * @param packet - the packet that will be received by the server.
+	 */
+	public void receivePacket(Channel channel, Packet<?> packet) {
+		channel.pipeline().context("encoder").fireChannelRead(packet);
+	}
+
+	/**
+	 * Add a custom channel handler to the given player's channel pipeline, allowing us to intercept sent and received packets.
+	 * <p>
+	 * This will automatically be called when a player has logged in.
+	 *
+	 * @param player - the player to inject.
+	 */
+	public void injectPlayer(Player player) {
+		injectChannelInternal(getChannel(player)).player = player;
+	}
+
+	/**
+	 * Add a custom channel handler to the given channel.
+	 *
+	 * @param channel - the channel to inject.
+	 * @return The intercepted channel, or NULL if it has already been injected.
+	 */
+	public void injectChannel(Channel channel) {
+		injectChannelInternal(channel);
+	}
+
+	/**
+	 * Add a custom channel handler to the given channel.
+	 *
+	 * @param channel - the channel to inject.
+	 * @return The packet interceptor.
+	 */
+	private PacketInterceptor injectChannelInternal(Channel channel) {
+		try {
+			PacketInterceptor interceptor = (PacketInterceptor) channel.pipeline().get(HANDLER_NAME);
+
+			// Inject our packet interceptor
+			if (interceptor == null) {
+				interceptor = new PacketInterceptor();
+				channel.pipeline().addBefore("packet_handler", HANDLER_NAME, interceptor);
+				uninjectedChannels.remove(channel);
+			}
+
+			return interceptor;
+		} catch (IllegalArgumentException e) {
+			// Try again
+			return (PacketInterceptor) channel.pipeline().get(HANDLER_NAME);
+		}
+	}
+
+	/**
+	 * Retrieve the Netty channel associated with a player. This is cached.
+	 *
+	 * @param player - the player.
+	 * @return The Netty channel.
+	 */
+	public Channel getChannel(Player player) {
+		Channel channel = channelLookup.get(player.getName());
+
+		// Lookup channel again
+		if (channel == null) {
+			Channel playerChannel = ((CraftPlayer) player).getHandle().connection.connection.channel;
+			channelLookup.put(player.getName(), channel = playerChannel);
+		}
+
+		return channel;
+	}
+
+	/**
+	 * Uninject a specific player.
+	 *
+	 * @param player - the injected player.
+	 */
+	public void uninjectPlayer(Player player) {
+		uninjectChannel(getChannel(player));
+	}
+
+	/**
+	 * Uninject a specific channel.
+	 * <p>
+	 * This will also disable the automatic channel injection that occurs when a player has properly logged in.
+	 *
+	 * @param channel - the injected channel.
+	 */
+	public void uninjectChannel(final Channel channel) {
+		// No need to guard against this if we're closing
+		if (!closed) {
+			uninjectedChannels.add(channel);
+		}
+
+		// See ChannelInjector in ProtocolLib, line 590
+		channel.eventLoop().execute(new Runnable() {
+
+			@Override
+			public void run() {
+				channel.pipeline().remove(HANDLER_NAME);
+			}
+
+		});
+	}
+
+	/**
+	 * Determine if the given player has been injected by TinyProtocol.
+	 *
+	 * @param player - the player.
+	 * @return TRUE if it is, FALSE otherwise.
+	 */
+	public boolean hasInjected(Player player) {
+		return hasInjected(getChannel(player));
+	}
+
+	/**
+	 * Determine if the given channel has been injected by TinyProtocol.
+	 *
+	 * @param channel - the channel.
+	 * @return TRUE if it is, FALSE otherwise.
+	 */
+	public boolean hasInjected(Channel channel) {
+		return channel.pipeline().get(HANDLER_NAME) != null;
+	}
+
+	/**
+	 * Cease listening for packets. This is called automatically when your plugin is disabled.
+	 */
 	public final void close() {
-		plugin.getLogger().log(Level.INFO, "Closing PacketInterceptor", new Exception("Stacktrace"));
+		if (!closed) {
+			closed = true;
 
-		if(closed)
+			// Remove our handlers
-			return;
+			for (Player player : plugin.getServer().getOnlinePlayers()) {
-		closed = true;
+				uninjectPlayer(player);
+			}
 
-		HandlerList.unregisterAll(this);
+			// Clean up Bukkit
-
+			HandlerList.unregisterAll(listener);
-		for (Player player : plugin.getServer().getOnlinePlayers()) {
+			unregisterChannelHandler();
-			getInterceptor(player).ifPresent(PacketInterceptor::close);
 		}
 	}
 
-	private Optional<PacketInterceptor> getInterceptor(Player player) {
+	/**
-		synchronized (playerInterceptors) {
+	 * Channel handler that is inserted into the player's channel pipeline, allowing us to intercept sent and received packets.
-			return Optional.ofNullable(playerInterceptors.get(player));
+	 *
-		}
+	 * @author Kristian
-	}
+	 */
-
+	private final class PacketInterceptor extends ChannelDuplexHandler {
-	private static final Field<Channel> getChannel = Reflection.getField(networkManager, Channel.class, 0);
+		// Updated by the login event
-	private static final Field<UUID> getUUID = Reflection.getField(networkManager, UUID.class, 0);
+		public volatile Player player;
-
-	public final class PacketInterceptor extends ChannelDuplexHandler {
-		private final Player player;
-		@Getter
-		private final Channel channel;
-
-		private PacketInterceptor(Player player) {
-			this.player = player;
-
-			channel = connections.stream().filter(connection -> player.getUniqueId().equals(getUUID.get(connection))).map(getChannel::get).filter(Channel::isActive).findAny().orElseThrow(() -> {
-				Bukkit.getScheduler().runTask(plugin, () -> player.kickPlayer("Connection failure."));
-				return new SecurityException("Could not find channel for player " + player.getName());
-			});
-
-			if(!channel.isActive())
-				return;
-
-			synchronized (playerInterceptors) {
-				playerInterceptors.put(player, this);
-			}
-			plugin.getLogger().info("Adding Techhider for: " + player.getName());
-
-			try {
-				channel.pipeline().addBefore("packet_handler", HANDLER_NAME, this);
-			} catch (IllegalArgumentException | NoSuchElementException e) {
-				Bukkit.getScheduler().runTask(plugin, () -> player.kickPlayer("Connection failure."));
-				throw new SecurityException(e);
-			}
-        }
-
-		private void sendPacket(Object packet) {
-			channel.pipeline().writeAndFlush(packet);
-		}
-
-		private void receivePacket(Object packet) {
-			channel.pipeline().context("encoder").fireChannelRead(packet);
-		}
-
-		private void close() {
-			if(channel.isActive()) {
-				channel.eventLoop().execute(() -> {
-					try {
-						channel.pipeline().remove(HANDLER_NAME);
-					} catch (NoSuchElementException e) {
-						// ignore
-					}
-				});
-			}
-
-			synchronized (playerInterceptors) {
-				playerInterceptors.remove(player, this);
-			}
-		}
 
 		@Override
 		public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
+			// Intercept channel
+			final Channel channel = ctx.channel();
+			handleLoginStart(channel, msg);
+
 			try {
 				msg = filterPacket(player, msg);
 			} catch (Exception e) {
-				plugin.getLogger().log(Level.SEVERE, "Error during incoming packet processing", e);
+				plugin.getLogger().log(Level.SEVERE, "Error in onPacketInAsync().", e);
 			}
 
 			if (msg != null) {
@@ -230,7 +468,7 @@ public class TinyProtocol implements Listener {
 			try {
 				msg = filterPacket(player, msg);
 			} catch (Exception e) {
-				plugin.getLogger().log(Level.SEVERE, "Error during outgoing packet processing", e);
+				plugin.getLogger().log(Level.SEVERE, "Error in onPacketOutAsync().", e);
 			}
 
 			if (msg != null) {
@@ -238,17 +476,21 @@ public class TinyProtocol implements Listener {
 			}
 		}
 
+		private void handleLoginStart(Channel channel, Object packet) {
+			if (packet instanceof ServerboundHelloPacket(String name, UUID packetId)) {
+				channelLookup.put(name, channel);
+			}
+		}
+
 		private Object filterPacket(Player player, Object packet) {
 			List<BiFunction<Player, Object, Object>> filters = packetFilters.getOrDefault(packet.getClass(), Collections.emptyList());
 
 			for(BiFunction<Player, Object, Object> filter : filters) {
 				packet = filter.apply(player, packet);
-
+				if(packet == null) break;
-				if(packet == null)
-					break;
 			}
 
 			return packet;
 		}
 	}
-}
+}

SpigotCore/SpigotCore_Main/src/de/steamwar/core/CheckpointUtilsJ9.java

@@ -23,6 +23,8 @@ import com.comphenix.tinyprotocol.TinyProtocol;
 import de.steamwar.Reflection;
 import de.steamwar.sql.internal.Statement;
 import io.netty.channel.ChannelFuture;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.network.ServerConnectionListener;
 import org.bukkit.Bukkit;
 import org.eclipse.openj9.criu.CRIUSupport;
 import org.eclipse.openj9.criu.JVMCRIUException;
@@ -56,7 +58,7 @@ class CheckpointUtilsJ9 {
 
         Bukkit.getOnlinePlayers().forEach(player -> player.kickPlayer(null));
 
-        List<?> networkManagers = TinyProtocol.networkManagers.get(TinyProtocol.getServerConnection(Core.getInstance()));
+        List<?> networkManagers = TinyProtocol.instance.networkManagers;
         if(!Bukkit.getOnlinePlayers().isEmpty() || !networkManagers.isEmpty()) {
             Core.getInstance().getLogger().log(Level.INFO, "Waiting for players to disconnect for checkpointing");
             Bukkit.getScheduler().runTaskLater(Core.getInstance(), CheckpointUtils::freeze, 1);
@@ -90,8 +92,8 @@ class CheckpointUtilsJ9 {
     }
 
 
-    private static final Reflection.Field<List> channelFutures = Reflection.getField(TinyProtocol.serverConnection, List.class, 0, ChannelFuture.class);
+    private static final Reflection.Field<List> channelFutures = Reflection.getField(ServerConnectionListener.class, List.class, 0, ChannelFuture.class);
-    private static final Reflection.Method bind = Reflection.getMethod(TinyProtocol.serverConnection, null, InetAddress.class, int.class);
+    private static final Reflection.Method bind = Reflection.getMethod(ServerConnectionListener.class, null, InetAddress.class, int.class);
     private static void freezeInternal(Path path) throws Exception {
         Bukkit.getPluginManager().callEvent(new CRIUSleepEvent());
 
@@ -99,7 +101,7 @@ class CheckpointUtilsJ9 {
         Statement.closeAll();
 
         // Close socket
-        Object serverConnection = TinyProtocol.getServerConnection(Core.getInstance());
+        ServerConnectionListener serverConnection = MinecraftServer.getServer().getConnection();
         List<?> channels = channelFutures.get(serverConnection);
         for(Object future : channels) {
             ((ChannelFuture) future).channel().close().syncUninterruptibly();