Fix null connection issues

SpigotCore_Main/src/com/comphenix/tinyprotocol/Reflection.java

@@ -7,6 +7,7 @@ import org.bukkit.Bukkit;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
 import java.util.Arrays;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -135,15 +136,16 @@ public final class Reflection {
 		return getField(getClass(className), fieldType, index);
 	}
 
-	// Common method
-	private static <T> FieldAccessor<T> getField(Class<?> target, String name, Class<T> fieldType, int index) {
+	public static <T> FieldAccessor<T> getField(Class<?> target, Class<T> fieldType, int index, Class<?>... parameters) {
+		return getField(target, null, fieldType, index, parameters);
+	}
+
+	private static <T> FieldAccessor<T> getField(Class<?> target, String name, Class<T> fieldType, int index, Class<?>... parameters) {
 		for (final Field field : target.getDeclaredFields()) {
-			if ((name == null || field.getName().equals(name)) && fieldType.isAssignableFrom(field.getType()) && index-- <= 0) {
+			if(matching(field, name, fieldType, parameters) && index-- <= 0) {
 				field.setAccessible(true);
 
-				// A function for retrieving a specific field value
 				return new FieldAccessor<T>() {
-
 					@Override
 					@SuppressWarnings("unchecked")
 					public T get(Object target) {
@@ -179,6 +181,24 @@ public final class Reflection {
 		throw new IllegalArgumentException("Cannot find field with type " + fieldType);
 	}
 
+	private static <T> boolean matching(Field field, String name, Class<T> fieldType, Class<?>... parameters) {
+		if(name != null && !field.getName().equals(name))
+			return false;
+
+		if(!fieldType.isAssignableFrom(field.getType()))
+			return false;
+
+		if(parameters.length > 0) {
+			Class<?>[] arguments = (Class<?>[]) ((ParameterizedType)field.getType().getGenericSuperclass()).getActualTypeArguments();
+
+			for(int i = 0; i < parameters.length; i++) {
+				if(arguments[i] != parameters[i])
+					return false;
+			}
+		}
+		return true;
+	}
+
 	/**
 	 * Search for the first publicly and privately defined method of the given name and parameter count.
 	 * 

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

@@ -1,7 +1,6 @@
 package com.comphenix.tinyprotocol;
 
 import com.comphenix.tinyprotocol.Reflection.FieldAccessor;
-import com.comphenix.tinyprotocol.Reflection.MethodInvoker;
 import de.steamwar.core.Core;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelDuplexHandler;
@@ -29,8 +28,20 @@ public class TinyProtocol implements Listener {
 		//enforce init
 	}
 
+	private static final Class<?> craftServer = Reflection.getClass("{obc}.CraftServer");
+	private static final Class<?> dedicatedPlayerList = Reflection.getClass("{nms.server.dedicated}.DedicatedPlayerList");
+	private static final FieldAccessor<?> getPlayerList = Reflection.getField(craftServer, dedicatedPlayerList, 0);
+	private static final Class<?> playerList = Reflection.getClass("{nms.server.players}.PlayerList");
+	private static final Class<?> minecraftServer = Reflection.getClass("{nms.server}.MinecraftServer");
+	private static final FieldAccessor<?> getMinecraftServer = Reflection.getField(playerList, minecraftServer, 0);
+	private static final Class<?> serverConnection = Reflection.getClass("{nms.server.network}.ServerConnection");
+	private static final FieldAccessor<?> getServerConnection = Reflection.getField(minecraftServer, serverConnection, 0);
+	private static final Class<?> networkManager = Reflection.getClass("{nms.network}.NetworkManager");
+	private static final FieldAccessor<List> getConnections = Reflection.getField(serverConnection, List.class, 0, networkManager);
+
 	private final Plugin plugin;
 	private final String handlerName;
+	private final List<?> connections;
 	private boolean closed;
 
 	private final Map<Class<?>, List<BiFunction<Player, Object, Object>>> packetFilters = new HashMap<>();
@@ -38,11 +49,9 @@ public class TinyProtocol implements Listener {
 
 	private TinyProtocol(final Plugin plugin) {
 		this.plugin = plugin;
-
-		// Compute handler name
 		this.handlerName = "tiny-" + plugin.getName() + "-" + ++id;
+		this.connections = getConnections.get(getServerConnection.get(getMinecraftServer.get(getPlayerList.get(plugin.getServer()))));
 
-		// Prepare existing players
 		plugin.getServer().getPluginManager().registerEvents(this, plugin);
 
 		for (Player player : plugin.getServer().getOnlinePlayers()) {
@@ -103,12 +112,8 @@ public class TinyProtocol implements Listener {
 		}
 	}
 
-	private static final MethodInvoker getPlayerHandle = Reflection.getMethod("{obc}.entity.CraftPlayer", "getHandle");
-	private static final Class<Object> playerConnection = Reflection.getUntypedClass("{nms.server.network}.PlayerConnection");
-	private static final FieldAccessor<Object> getConnection = Reflection.getField("{nms.server.level}.EntityPlayer", playerConnection, 0);
-	private static final Class<Object> networkManager = Reflection.getUntypedClass("{nms.network}.NetworkManager");
-	private static final FieldAccessor<Object> getManager = Reflection.getField(playerConnection, networkManager, 0);
 	private static final FieldAccessor<Channel> getChannel = Reflection.getField(networkManager, Channel.class, 0);
+	private static final FieldAccessor<UUID> getUUID = Reflection.getField(networkManager, UUID.class, 0);
 
 	private final class PacketInterceptor extends ChannelDuplexHandler {
 		private final Player player;
@@ -117,9 +122,7 @@ public class TinyProtocol implements Listener {
 		private PacketInterceptor(Player player) {
 			this.player = player;
 
-			Object connection = getConnection.get(getPlayerHandle.invoke(player));
-			Object manager = getManager.get(connection);
-			channel = getChannel.get(manager);
+			channel = getChannel.get(connections.stream().filter(connection -> player.getUniqueId().equals(getUUID.get(connection))).findAny().orElseThrow(() -> new SecurityException("Could not find channel for player " + player.getName())));
 
 			synchronized (playerInterceptors) {
 				playerInterceptors.put(player, this);