Updated the library.

api/src/main/java/com/comphenix/tinyprotocol/Reflection.java

@@ -0,0 +1,397 @@
+/*
+ * Copyright (c) 2018 Jitse Boonstra
+ */
+
+package com.comphenix.tinyprotocol;
+
+import org.bukkit.Bukkit;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * An utility class that simplifies reflection in Bukkit plugins.
+ *
+ * @author Kristian
+ */
+public final class Reflection {
+    /**
+     * An interface for invoking a specific constructor.
+     */
+    public interface ConstructorInvoker {
+        /**
+         * Invoke a constructor for a specific class.
+         *
+         * @param arguments - the arguments to pass to the constructor.
+         * @return The constructed object.
+         */
+        Object invoke(Object... arguments);
+    }
+
+    /**
+     * An interface for invoking a specific method.
+     */
+    public interface MethodInvoker {
+        /**
+         * Invoke a method on a specific target object.
+         *
+         * @param target    - the target object, or NULL for a static method.
+         * @param arguments - the arguments to pass to the method.
+         * @return The return value, or NULL if is void.
+         */
+        Object invoke(Object target, Object... arguments);
+    }
+
+    /**
+     * An interface for retrieving the field content.
+     *
+     * @param <T> - field type.
+     */
+    public interface FieldAccessor<T> {
+        /**
+         * Retrieve the content of a field.
+         *
+         * @param target - the target object, or NULL for a static field.
+         * @return The value of the field.
+         */
+        T get(Object target);
+
+        /**
+         * Set the content of a field.
+         *
+         * @param target - the target object, or NULL for a static field.
+         * @param value  - the new value of the field.
+         */
+        void set(Object target, Object value);
+
+        /**
+         * Determine if the given object has this field.
+         *
+         * @param target - the object to test.
+         * @return TRUE if it does, FALSE otherwise.
+         */
+        boolean hasField(Object target);
+    }
+
+    // Deduce the net.minecraft.server.v* package
+    private static String OBC_PREFIX = Bukkit.getServer().getClass().getPackage().getName();
+    private static String NMS_PREFIX = OBC_PREFIX.replace("org.bukkit.craftbukkit", "net.minecraft.server");
+    private static String VERSION = OBC_PREFIX.replace("org.bukkit.craftbukkit", "").replace(".", "");
+
+    // Variable replacement
+    private static Pattern MATCH_VARIABLE = Pattern.compile("\\{([^}]+)\\}");
+
+    private Reflection() {
+        // Seal class
+    }
+
+    /**
+     * Retrieve a field accessor for a specific field type and name.
+     *
+     * @param target    - the target type.
+     * @param name      - the name of the field, or NULL to ignore.
+     * @param fieldType - a compatible field type.
+     * @return The field accessor.
+     */
+    public static <T> FieldAccessor<T> getField(Class<?> target, String name, Class<T> fieldType) {
+        return getField(target, name, fieldType, 0);
+    }
+
+    /**
+     * Retrieve a field accessor for a specific field type and name.
+     *
+     * @param className - lookup name of the class, see {@link #getClass(String)}.
+     * @param name      - the name of the field, or NULL to ignore.
+     * @param fieldType - a compatible field type.
+     * @return The field accessor.
+     */
+    public static <T> FieldAccessor<T> getField(String className, String name, Class<T> fieldType) {
+        return getField(getClass(className), name, fieldType, 0);
+    }
+
+    /**
+     * Retrieve a field accessor for a specific field type and name.
+     *
+     * @param target    - the target type.
+     * @param fieldType - a compatible field type.
+     * @param index     - the number of compatible fields to skip.
+     * @return The field accessor.
+     */
+    public static <T> FieldAccessor<T> getField(Class<?> target, Class<T> fieldType, int index) {
+        return getField(target, null, fieldType, index);
+    }
+
+    /**
+     * Retrieve a field accessor for a specific field type and name.
+     *
+     * @param className - lookup name of the class, see {@link #getClass(String)}.
+     * @param fieldType - a compatible field type.
+     * @param index     - the number of compatible fields to skip.
+     * @return The field accessor.
+     */
+    public static <T> FieldAccessor<T> getField(String className, Class<T> fieldType, int index) {
+        return getField(getClass(className), fieldType, index);
+    }
+
+    // Common method
+    private static <T> FieldAccessor<T> getField(Class<?> target, String name, Class<T> fieldType, int index) {
+        for (final Field field : target.getDeclaredFields()) {
+            if ((name == null || field.getName().equals(name)) && fieldType.isAssignableFrom(field.getType()) && 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) {
+                        try {
+                            return (T) field.get(target);
+                        } catch (IllegalAccessException e) {
+                            throw new RuntimeException("Cannot access reflection.", e);
+                        }
+                    }
+
+                    @Override
+                    public void set(Object target, Object value) {
+                        try {
+                            field.set(target, value);
+                        } catch (IllegalAccessException e) {
+                            throw new RuntimeException("Cannot access reflection.", e);
+                        }
+                    }
+
+                    @Override
+                    public boolean hasField(Object target) {
+                        // target instanceof DeclaringClass
+                        return field.getDeclaringClass().isAssignableFrom(target.getClass());
+                    }
+                };
+            }
+        }
+
+        // Search in parent classes
+        if (target.getSuperclass() != null)
+            return getField(target.getSuperclass(), name, fieldType, index);
+
+        throw new IllegalArgumentException("Cannot find field with type " + fieldType);
+    }
+
+    /**
+     * Search for the first publicly and privately defined method of the  given name and parameter count.
+     *
+     * @param className  - lookup name of the class, see {@link #getClass(String)}.
+     * @param methodName - the method name, or NULL to skip.
+     * @param params     - the expected parameters.
+     * @return An object that invokes this specific method.
+     * @throws IllegalStateException If we cannot find this method.
+     */
+    public static MethodInvoker getMethod(String className, String methodName, Class<?>... params) {
+        return getTypedMethod(getClass(className), methodName, null, params);
+    }
+
+    /**
+     * Search for the first publicly and privately defined method of the given name and parameter count.
+     *
+     * @param clazz      - a class to start with.
+     * @param methodName - the method name, or NULL to skip.
+     * @param params     - the expected parameters.
+     * @return An object that invokes this specific method.
+     * @throws IllegalStateException If we cannot find this method.
+     */
+    public static MethodInvoker getMethod(Class<?> clazz, String methodName, Class<?>... params) {
+        return getTypedMethod(clazz, methodName, null, params);
+    }
+
+    /**
+     * Search for the first publicly and privately defined method of the given name and parameter count.
+     *
+     * @param clazz      - a class to start with.
+     * @param methodName - the method name, or NULL to skip.
+     * @param returnType - the expected return type, or NULL to ignore.
+     * @param params     - the expected parameters.
+     * @return An object that invokes this specific method.
+     * @throws IllegalStateException If we cannot find this method.
+     */
+    public static MethodInvoker getTypedMethod(Class<?> clazz, String methodName, Class<?> returnType, Class<?>... params) {
+        for (final Method method : clazz.getDeclaredMethods()) {
+            if ((methodName == null || method.getName().equals(methodName))
+                    && (returnType == null || method.getReturnType().equals(returnType))
+                    && Arrays.equals(method.getParameterTypes(), params)) {
+                method.setAccessible(true);
+
+                return (target, arguments) -> {
+                    try {
+                        return method.invoke(target, arguments);
+                    } catch (Exception e) {
+                        throw new RuntimeException("Cannot invoke method " + method, e);
+                    }
+                };
+            }
+        }
+
+        // Search in every superclass
+        if (clazz.getSuperclass() != null)
+            return getMethod(clazz.getSuperclass(), methodName, params);
+
+        throw new IllegalStateException(String.format("Unable to find method %s (%s).", methodName, Arrays.asList(params)));
+    }
+
+    /**
+     * Search for the first publically and privately defined constructor of the given name and parameter count.
+     *
+     * @param className - lookup name of the class, see {@link #getClass(String)}.
+     * @param params    - the expected parameters.
+     * @return An object that invokes this constructor.
+     * @throws IllegalStateException If we cannot find this method.
+     */
+    public static ConstructorInvoker getConstructor(String className, Class<?>... params) {
+        return getConstructor(getClass(className), params);
+    }
+
+    /**
+     * Search for the first publicly and privately defined constructor of the given name and parameter count.
+     *
+     * @param clazz  - a class to start with.
+     * @param params - the expected parameters.
+     * @return An object that invokes this constructor.
+     * @throws IllegalStateException If we cannot find this method.
+     */
+    public static ConstructorInvoker getConstructor(Class<?> clazz, Class<?>... params) {
+        for (final Constructor<?> constructor : clazz.getDeclaredConstructors()) {
+            if (Arrays.equals(constructor.getParameterTypes(), params)) {
+                constructor.setAccessible(true);
+
+                return arguments -> {
+                    try {
+                        return constructor.newInstance(arguments);
+                    } catch (Exception e) {
+                        throw new RuntimeException("Cannot invoke constructor " + constructor, e);
+                    }
+                };
+            }
+        }
+
+        throw new IllegalStateException(String.format("Unable to find constructor for %s (%s).", clazz, Arrays.asList(params)));
+    }
+
+    /**
+     * Retrieve a class from its full name, without knowing its type on compile time.
+     * <p>
+     * This is useful when looking up fields by a NMS or OBC type.
+     * <p>
+     *
+     * @param lookupName - the class name with variables.
+     * @return The class.
+     * @see {@link #getClass()} for more information.
+     */
+    public static Class<Object> getUntypedClass(String lookupName) {
+        @SuppressWarnings({"rawtypes", "unchecked"})
+        Class<Object> clazz = (Class) getClass(lookupName);
+        return clazz;
+    }
+
+    /**
+     * Retrieve a class from its full name.
+     * <p>
+     * Strings enclosed with curly brackets - such as {TEXT} - will be replaced according to the following table:
+     *
+     * <table border="1">
+     * <tr>
+     * <th>Variable</th>
+     * <th>Content</th>
+     * </tr>
+     * <tr>
+     * <td>{nms}</td>
+     * <td>Actual package name of net.minecraft.server.VERSION</td>
+     * </tr>
+     * <tr>
+     * <td>{obc}</td>
+     * <td>Actual pacakge name of org.bukkit.craftbukkit.VERSION</td>
+     * </tr>
+     * <tr>
+     * <td>{version}</td>
+     * <td>The current Minecraft package VERSION, if any.</td>
+     * </tr>
+     * </table>
+     *
+     * @param lookupName - the class name with variables.
+     * @return The looked up class.
+     * @throws IllegalArgumentException If a variable or class could not be found.
+     */
+    public static Class<?> getClass(String lookupName) {
+        return getCanonicalClass(expandVariables(lookupName));
+    }
+
+    /**
+     * Retrieve a class in the net.minecraft.server.VERSION.* package.
+     *
+     * @param name - the name of the class, excluding the package.
+     * @throws IllegalArgumentException If the class doesn't exist.
+     */
+    public static Class<?> getMinecraftClass(String name) {
+        return getCanonicalClass(NMS_PREFIX + "." + name);
+    }
+
+    /**
+     * Retrieve a class in the org.bukkit.craftbukkit.VERSION.* package.
+     *
+     * @param name - the name of the class, excluding the package.
+     * @throws IllegalArgumentException If the class doesn't exist.
+     */
+    public static Class<?> getCraftBukkitClass(String name) {
+        return getCanonicalClass(OBC_PREFIX + "." + name);
+    }
+
+    /**
+     * Retrieve a class by its canonical name.
+     *
+     * @param canonicalName - the canonical name.
+     * @return The class.
+     */
+    private static Class<?> getCanonicalClass(String canonicalName) {
+        try {
+            return Class.forName(canonicalName);
+        } catch (ClassNotFoundException e) {
+            throw new IllegalArgumentException("Cannot find " + canonicalName, e);
+        }
+    }
+
+    /**
+     * Expand variables such as "{nms}" and "{obc}" to their corresponding packages.
+     *
+     * @param name - the full name of the class.
+     * @return The expanded string.
+     */
+    private static String expandVariables(String name) {
+        StringBuffer output = new StringBuffer();
+        Matcher matcher = MATCH_VARIABLE.matcher(name);
+
+        while (matcher.find()) {
+            String variable = matcher.group(1);
+            String replacement;
+
+            // Expand all detected variables
+            if ("nms".equalsIgnoreCase(variable))
+                replacement = NMS_PREFIX;
+            else if ("obc".equalsIgnoreCase(variable))
+                replacement = OBC_PREFIX;
+            else if ("version".equalsIgnoreCase(variable))
+                replacement = VERSION;
+            else
+                throw new IllegalArgumentException("Unknown variable: " + variable);
+
+            // Assume the expanded variables are all packages, and append a dot
+            if (replacement.length() > 0 && matcher.end() < name.length() && name.charAt(matcher.end()) != '.')
+                replacement += ".";
+            matcher.appendReplacement(output, Matcher.quoteReplacement(replacement));
+        }
+
+        matcher.appendTail(output);
+        return output.toString();
+    }
+}

api/src/main/java/com/comphenix/tinyprotocol/TinyProtocol.java

@@ -0,0 +1,324 @@
+/*
+ * Copyright (c) 2018 Jitse Boonstra
+ */
+
+package com.comphenix.tinyprotocol;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.MapMaker;
+import io.netty.channel.*;
+import net.jitse.npclib.NPCLib;
+import org.bukkit.Bukkit;
+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.server.PluginDisableEvent;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Minimized version of TinyProtocol by Kristian suited for NPCLib.
+ */
+public abstract class TinyProtocol {
+
+    private static final AtomicInteger ID = new AtomicInteger(0);
+
+    // Used in order to lookup a channel
+    private static final Reflection.MethodInvoker getPlayerHandle = Reflection.getMethod("{obc}.entity.CraftPlayer", "getHandle");
+    private static final Reflection.FieldAccessor<Object> getConnection = Reflection.getField("{nms}.EntityPlayer", "playerConnection", Object.class);
+    private static final Reflection.FieldAccessor<Object> getManager = Reflection.getField("{nms}.PlayerConnection", "networkManager", Object.class);
+    private static final Reflection.FieldAccessor<Channel> getChannel = Reflection.getField("{nms}.NetworkManager", Channel.class, 0);
+
+    // Looking up ServerConnection
+    private static final Class<Object> minecraftServerClass = Reflection.getUntypedClass("{nms}.MinecraftServer");
+    private static final Class<Object> serverConnectionClass = Reflection.getUntypedClass("{nms}.ServerConnection");
+    private static final Reflection.FieldAccessor<Object> getMinecraftServer = Reflection.getField("{obc}.CraftServer", minecraftServerClass, 0);
+    private static final Reflection.FieldAccessor<Object> getServerConnection = Reflection.getField(minecraftServerClass, serverConnectionClass, 0);
+    private static final Reflection.MethodInvoker getNetworkMarkers = Reflection.getTypedMethod(serverConnectionClass, null, List.class, serverConnectionClass);
+
+    // Packets we have to intercept
+    private static final Class<?> PACKET_LOGIN_IN_START = Reflection.getMinecraftClass("PacketLoginInStart");
+    private static final Reflection.FieldAccessor getGameProfile = Reflection.getField(PACKET_LOGIN_IN_START,
+            Reflection.getClass("com.mojang.authlib.GameProfile"), 0);
+
+    // Speedup channel lookup
+    private Map<String, Channel> channelLookup = new MapMaker().weakValues().makeMap();
+    private Listener listener;
+
+    // Channels that have already been removed
+    private Set<Channel> uninjectedChannels = Collections.newSetFromMap(new MapMaker().weakKeys().makeMap());
+
+    // List of network markers
+    private List<Object> networkManagers;
+
+    private final NPCLib instance;
+
+    // Injected channel handlers
+    private List<Channel> serverChannels = Lists.newArrayList();
+    private ChannelInboundHandlerAdapter serverChannelHandler;
+    private ChannelInitializer<Channel> beginInitProtocol;
+    private ChannelInitializer<Channel> endInitProtocol;
+
+    // Current handler name
+    private String handlerName;
+
+    private volatile boolean closed;
+    protected Plugin plugin;
+
+    protected TinyProtocol(NPCLib instance) {
+        this.plugin = instance.getPlugin();
+        this.instance = instance;
+
+        // Compute handler name
+        this.handlerName = "tiny-" + plugin.getName() + "-" + ID.incrementAndGet();
+
+        // Prepare existing players
+        registerBukkitEvents();
+
+        try {
+            instance.getLogger().info("Attempting to inject into netty");
+            registerChannelHandler();
+            registerPlayers(plugin);
+        } catch (IllegalArgumentException exception) {
+            // Damn you, late bind
+            instance.getLogger().warning("Attempting to delay injection");
+
+            new BukkitRunnable() {
+                @Override
+                public void run() {
+                    registerChannelHandler();
+                    registerPlayers(plugin);
+                    instance.getLogger().info("Injection complete");
+                }
+            }.runTask(plugin);
+        }
+    }
+
+    private void createServerChannelHandler() {
+        // Handle connected channels
+        endInitProtocol = new ChannelInitializer<Channel>() {
+
+            @SuppressWarnings("all")
+            @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 exception) {
+                    instance.getLogger().severe("Cannot inject incomming channel " + channel + ". Message: "
+                            + exception.getMessage());
+                }
+            }
+
+        };
+
+        // This is executed before Minecraft's channel handler
+        beginInitProtocol = new ChannelInitializer<Channel>() {
+
+            @SuppressWarnings("all")
+            @Override
+            protected void initChannel(Channel channel) throws Exception {
+                channel.pipeline().addLast(endInitProtocol);
+            }
+
+        };
+
+        serverChannelHandler = new ChannelInboundHandlerAdapter() {
+
+            @SuppressWarnings("all")
+            @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);
+            }
+
+        };
+    }
+
+    private void registerBukkitEvents() {
+        listener = new Listener() {
+
+            @SuppressWarnings("unused")
+            @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());
+                }
+            }
+
+            @SuppressWarnings("unused")
+            @EventHandler
+            public final void onPluginDisable(PluginDisableEvent e) {
+                if (e.getPlugin().equals(plugin)) {
+                    close();
+                }
+            }
+
+        };
+
+        plugin.getServer().getPluginManager().registerEvents(listener, plugin);
+    }
+
+    @SuppressWarnings("unchecked")
+    private void registerChannelHandler() {
+        Object mcServer = getMinecraftServer.get(Bukkit.getServer());
+        Object serverConnection = getServerConnection.get(mcServer);
+        boolean looking = true;
+
+        // We need to synchronize against this list
+        networkManagers = (List<Object>) getNetworkMarkers.invoke(null, serverConnection);
+        createServerChannelHandler();
+
+        // Find the correct list, or implicitly throw an exception
+        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;
+
+        for (Channel serverChannel : serverChannels) {
+            final ChannelPipeline pipeline = serverChannel.pipeline();
+
+            // Remove channel handler
+            serverChannel.eventLoop().execute(() -> {
+                try {
+                    pipeline.remove(serverChannelHandler);
+                } catch (NoSuchElementException exception) {
+                    // That's fine
+                }
+            });
+        }
+    }
+
+    private void registerPlayers(Plugin plugin) {
+        for (Player player : plugin.getServer().getOnlinePlayers()) {
+            injectPlayer(player);
+        }
+    }
+
+    public Object onPacketInAsync(Player sender, Object packet) {
+        return packet;
+    }
+
+    private void injectPlayer(Player player) {
+        injectChannelInternal(getChannel(player)).player = player;
+    }
+
+    private PacketInterceptor injectChannelInternal(Channel channel) {
+        try {
+            PacketInterceptor interceptor = (PacketInterceptor) channel.pipeline().get(handlerName);
+
+            // Inject our packet interceptor
+            if (interceptor == null) {
+                interceptor = new PacketInterceptor();
+                channel.pipeline().addBefore("packet_handler", handlerName, interceptor);
+                uninjectedChannels.remove(channel);
+            }
+
+            return interceptor;
+        } catch (IllegalArgumentException exception) {
+            // Try again
+            return (PacketInterceptor) channel.pipeline().get(handlerName);
+        }
+    }
+
+    private Channel getChannel(Player player) {
+        Channel channel = channelLookup.get(player.getName());
+
+        // Lookup channel again
+        if (channel == null) {
+            Object connection = getConnection.get(getPlayerHandle.invoke(player));
+            Object manager = getManager.get(connection);
+
+            channelLookup.put(player.getName(), channel = getChannel.get(manager));
+        }
+
+        return channel;
+    }
+
+    private void close() {
+        if (!closed) {
+            closed = true;
+
+            // Remove our handlers
+            for (Player player : plugin.getServer().getOnlinePlayers()) {
+                // No need to guard against this if we're closing
+                Channel channel = getChannel(player);
+                if (!closed) {
+                    uninjectedChannels.add(channel);
+                }
+
+                // See ChannelInjector in ProtocolLib, line 590
+                channel.eventLoop().execute(() -> channel.pipeline().remove(handlerName));
+            }
+
+            // Clean up Bukkit
+            HandlerList.unregisterAll(listener);
+            unregisterChannelHandler();
+        }
+    }
+
+    private final class PacketInterceptor extends ChannelDuplexHandler {
+        // Updated by the login event
+        public volatile Player player;
+
+        @Override
+        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
+            // Intercept channel
+            final Channel channel = ctx.channel();
+            handleLoginStart(channel, msg);
+
+            try {
+                msg = onPacketInAsync(player, msg);
+            } catch (Exception exception) {
+                instance.getLogger().severe("Error in onPacketInAsync(). Message: " + exception.getMessage());
+            }
+
+            if (msg != null) {
+                super.channelRead(ctx, msg);
+            }
+        }
+
+        private void handleLoginStart(Channel channel, Object packet) {
+            if (PACKET_LOGIN_IN_START.isInstance(packet)) {
+                Object profile = getGameProfile.get(packet);
+                channelLookup.put((String) Reflection.getMethod(profile.getClass(), "getName").invoke(profile), channel);
+            }
+        }
+    }
+}