Fixes #9 and added a debug option for the bungee plugin

bukkit/src/main/java/org/geysermc/floodgate/PacketHandler.java

@@ -2,7 +2,7 @@ package org.geysermc.floodgate;
 
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelHandlerContext;
-import io.netty.handler.codec.MessageToMessageDecoder;
+import io.netty.channel.SimpleChannelInboundHandler;
 import lombok.RequiredArgsConstructor;
 import org.geysermc.floodgate.HandshakeHandler.HandshakeResult;
 import org.geysermc.floodgate.injector.BukkitInjector;
@@ -14,13 +14,12 @@ import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
-import java.util.List;
 import java.util.UUID;
 
 import static org.geysermc.floodgate.util.ReflectionUtil.*;
 
 @RequiredArgsConstructor
-public class PacketHandler extends MessageToMessageDecoder<Object> {
+public class PacketHandler extends SimpleChannelInboundHandler<Object> {
     private static BukkitPlugin plugin = BukkitPlugin.getInstance();
     private static HandshakeHandler handshakeHandler;
 
@@ -52,7 +51,7 @@ public class PacketHandler extends MessageToMessageDecoder<Object> {
     private boolean bungee;
 
     @Override
-    protected void decode(ChannelHandlerContext ctx, Object packet, List<Object> out) throws Exception {
+    protected void channelRead0(ChannelHandlerContext ctx, Object packet) throws Exception {
         boolean isHandhake = handshakePacketClass.isInstance(packet);
         boolean isLogin = loginStartPacketClass.isInstance(packet);
 
@@ -94,7 +93,6 @@ public class PacketHandler extends MessageToMessageDecoder<Object> {
                     setValue(networkManager, getFieldOfType(networkManagerClass, SocketAddress.class, false), newAddress);
                 }
                 plugin.getLogger().info("Added " + fPlayer.getJavaUsername() + " " + fPlayer.getJavaUniqueId());
-                out.add(packet);
             } else if (isLogin) {
                 if (!bungee) {
                     // we have to fake the offline player cycle
@@ -109,9 +107,12 @@ public class PacketHandler extends MessageToMessageDecoder<Object> {
                     setValue(loginListener, protocolStateField, readyToAcceptState); // LoginLister#protocolState = READY_TO_ACCEPT
                     // The tick of LoginListener will do the rest
                 }
-                // out.add(packet); don't let this packet through as we want to skip the login cycle
             }
         } finally {
+            // don't let the packet through if the packet is the login packet
+            // because we want to skip the login cycle
+            if (!isLogin) ctx.fireChannelRead(packet);
+
             if (isHandhake && bungee || isLogin && !bungee || fPlayer == null) {
                 // remove the injection of the client because we're finished
                 BukkitInjector.removeInjectedClient(future, ctx.channel());

bungee/pom.xml

@@ -25,6 +25,12 @@
             <version>${bungee-version}</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>net.md-5</groupId>
+            <artifactId>bungeecord-protocol</artifactId>
+            <version>1.15-SNAPSHOT</version>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>org.geysermc</groupId>
             <artifactId>floodgate-common</artifactId>

bungee/src/main/java/org/geysermc/floodgate/BungeeDebugger.java

@@ -0,0 +1,108 @@
+package org.geysermc.floodgate;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.channel.*;
+import io.netty.channel.socket.ServerSocketChannel;
+import io.netty.handler.codec.MessageToByteEncoder;
+import lombok.RequiredArgsConstructor;
+import net.md_5.bungee.protocol.MinecraftEncoder;
+import net.md_5.bungee.protocol.Varint21LengthFieldPrepender;
+import org.geysermc.floodgate.util.ReflectionUtil;
+
+import java.lang.reflect.Field;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+
+public class BungeeDebugger {
+    public BungeeDebugger() {
+        init();
+    }
+
+    private void init() {
+        Class<?> pipelineUtils = ReflectionUtil.getPrefixedClass("netty.PipelineUtils");
+        Field framePrepender = ReflectionUtil.getField(pipelineUtils, "framePrepender");
+        ReflectionUtil.setFinalValue(null, framePrepender, new CustomVarint21LengthFieldPrepender());
+    }
+
+    @ChannelHandler.Sharable
+    private static class CustomVarint21LengthFieldPrepender extends Varint21LengthFieldPrepender {
+        @Override
+        public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
+            // we're getting called before the encoder and decoder are added,
+            // so we have to wait with a nice while loop :D
+            ctx.executor().execute(() -> {
+                System.out.println("Channel: " + ctx.channel().isActive() + " " + ctx.channel().isOpen() + " " + ctx.channel().isRegistered());
+                while (ctx.channel().isOpen()) {
+                    System.out.println("Trying to find decoder for " + getHostString(ctx, true) + " " + getParentName(ctx, true));
+                    if (ctx.channel().pipeline().get(MinecraftEncoder.class) != null) {
+                        System.out.println("Found decoder for " + getHostString(ctx, true));
+                        ctx.channel().pipeline().addLast(
+                                "floodgate-debug-init",
+                                new BungeeChannelInitializer(
+                                        ctx.channel().parent() instanceof ServerSocketChannel
+                                )
+                        );
+                        break;
+                    }
+                }
+            });
+        }
+    }
+
+    public static String getHostString(ChannelHandlerContext ctx, boolean alwaysString) {
+        SocketAddress address = ctx.channel().remoteAddress();
+        return address != null ? ((InetSocketAddress) address).getHostString() : (alwaysString ? "null" : null);
+    }
+
+    public static String getParentName(ChannelHandlerContext ctx, boolean alwaysString) {
+        Channel parent = ctx.channel().parent();
+        return parent != null ? parent.getClass().getSimpleName() : (alwaysString ? "null" : null);
+    }
+
+    public static int executorsCount(ChannelHandlerContext ctx) {
+        return ((MultithreadEventLoopGroup) ctx.channel().eventLoop().parent()).executorCount();
+    }
+
+    @RequiredArgsConstructor
+    private static class BungeeChannelInitializer extends ChannelInitializer<Channel> {
+        private final boolean player;
+
+        @Override
+        protected void initChannel(Channel channel) throws Exception {
+            System.out.println("Init " + (player ? "Bungee" : "Server"));
+            // can't add our debugger when the inbound-boss is missing
+            if (channel.pipeline().get("packet-encoder") == null) return;
+            if (channel.pipeline().get("packet-decoder") == null) return;
+            channel.pipeline()
+                    .addBefore("packet-decoder", "floodgate-debug-in", new BungeeInPacketHandler(player))
+                    .addBefore("packet-encoder", "floodgate-debug-out", new BungeeOutPacketHandler(player));
+        }
+    }
+
+    @RequiredArgsConstructor
+    private static class BungeeInPacketHandler extends SimpleChannelInboundHandler<ByteBuf> {
+        private final boolean player;
+
+        @Override
+        protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
+            int index = msg.readerIndex();
+            System.out.println((player ? "Player -> Bungee" : "Server -> Bungee") + ":\n" + ByteBufUtil.prettyHexDump(msg));
+            msg.readerIndex(index);
+            ctx.fireChannelRead(msg.retain());
+        }
+    }
+
+    @RequiredArgsConstructor
+    private static class BungeeOutPacketHandler extends MessageToByteEncoder<ByteBuf> {
+        private final boolean player;
+
+        @Override
+        protected void encode(ChannelHandlerContext ctx, ByteBuf msg, ByteBuf out) throws Exception {
+            int index = msg.readerIndex();
+            System.out.println((player ? "Bungee -> Player" : "Bungee -> Server") + ":\n" + ByteBufUtil.prettyHexDump(msg));
+            msg.readerIndex(index);
+            out.writeBytes(msg);
+        }
+    }
+}

bungee/src/main/java/org/geysermc/floodgate/BungeePlugin.java

@@ -25,6 +25,7 @@ public class BungeePlugin extends Plugin implements Listener {
     private static Field extraHandshakeData;
 
     @Getter private BungeeFloodgateConfig config;
+    private BungeeDebugger debugger;
     private HandshakeHandler handshakeHandler;
 
     @Override
@@ -40,6 +41,16 @@ public class BungeePlugin extends Plugin implements Listener {
     @Override
     public void onEnable() {
         getProxy().getPluginManager().registerListener(this, this);
+        if (config.isDebug()) {
+            debugger = new BungeeDebugger();
+        }
+    }
+
+    @Override
+    public void onDisable() {
+        if (config.isDebug()) {
+            getLogger().warning("Please note that it is not possible to reload this plugin when debug mode is enabled. At least for now");
+        }
     }
 
     @EventHandler(priority = EventPriority.LOW)
@@ -93,15 +104,15 @@ public class BungeePlugin extends Plugin implements Listener {
             SocketAddress remoteAddress = ReflectionUtil.getCastedValue(channelWrapper, "remoteAddress", SocketAddress.class);
             if (!(remoteAddress instanceof InetSocketAddress)) {
                 getLogger().info(
-                        "Player " + player.getUsername() + " doesn't use a InetSocketAddress. " +
+                        "Player " + player.getUsername() + " doesn't use an InetSocketAddress. " +
                         "It uses " + remoteAddress.getClass().getSimpleName() + ". Ignoring the player, I guess."
                 );
-                return;
+            } else {
+                ReflectionUtil.setValue(
+                        channelWrapper, "remoteAddress",
+                        new InetSocketAddress(result.getBedrockData().getIp(), ((InetSocketAddress) remoteAddress).getPort())
+                );
             }
-            ReflectionUtil.setValue(
-                    channelWrapper, "remoteAddress",
-                    new InetSocketAddress(result.getBedrockData().getIp(), ((InetSocketAddress) remoteAddress).getPort())
-            );
             event.completeIntent(this);
         });
     }
@@ -117,7 +128,8 @@ public class BungeePlugin extends Plugin implements Listener {
     }
 
     static {
-        Class<?> initial_handler = ReflectionUtil.getClass("net.md_5.bungee.connection.InitialHandler");
+        ReflectionUtil.setPrefix("net.md_5.bungee");
+        Class<?> initial_handler = ReflectionUtil.getPrefixedClass("connection.InitialHandler");
         extraHandshakeData = ReflectionUtil.getField(initial_handler, "extraDataInHandshake");
     }
 }

common/src/main/java/org/geysermc/floodgate/FloodgateConfig.java

@@ -26,6 +26,9 @@ public class FloodgateConfig {
     @JsonProperty(value = "disconnect")
     private DisconnectMessages messages;
 
+    @JsonProperty
+    private boolean debug;
+
     @JsonIgnore
     PrivateKey privateKey = null;
 

common/src/main/java/org/geysermc/floodgate/HandshakeHandler.java

@@ -1,9 +1,6 @@
 package org.geysermc.floodgate;
 
-import lombok.AccessLevel;
-import lombok.AllArgsConstructor;
-import lombok.Getter;
-import lombok.NonNull;
+import lombok.*;
 import org.geysermc.floodgate.util.BedrockData;
 import org.geysermc.floodgate.util.EncryptionUtil;
 
@@ -53,7 +50,7 @@ public class HandshakeHandler {
     }
 
     @AllArgsConstructor(access = AccessLevel.PROTECTED)
-    @Getter
+    @Getter @ToString
     public static class HandshakeResult {
         private ResultType resultType;
         private String[] handshakeData;

common/src/main/java/org/geysermc/floodgate/util/ReflectionUtil.java

@@ -3,10 +3,7 @@ package org.geysermc.floodgate.util;
 import lombok.Getter;
 import lombok.Setter;
 
-import java.lang.reflect.AccessibleObject;
-import java.lang.reflect.Field;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
+import java.lang.reflect.*;
 
 public class ReflectionUtil {
     /**
@@ -94,6 +91,39 @@ public class ReflectionUtil {
         }
     }
 
+    public static boolean setFinalValue(Object instance, Field field, Object value) {
+        try {
+            makeAccessible(field);
+
+            Field modifiersField = null;
+            int modifiers = field.getModifiers();
+            if (Modifier.isFinal(modifiers)) {
+                try {
+                    modifiersField = Field.class.getDeclaredField("modifiers");
+                } catch (NoSuchFieldException e) {
+                    // Java 12 compatibility, thanks to https://github.com/powermock/powermock/pull/1010
+                    Method getDeclaredFields0 = Class.class.getDeclaredMethod("getDeclaredFields0", boolean.class);
+                    makeAccessible(getDeclaredFields0);
+                    Field[] fields = (Field[]) getDeclaredFields0.invoke(Field.class, false);
+                    for (Field classField : fields) {
+                        if ("modifiers".equals(classField.getName())) {
+                            modifiersField = classField;
+                            break;
+                        }
+                    }
+                }
+                assert modifiersField != null;
+                makeAccessible(modifiersField);
+                modifiersField.setInt(field, modifiers & ~Modifier.FINAL);
+            }
+            setValue(instance, field, value);
+            return true;
+        } catch (Exception e) {
+            e.printStackTrace();
+            return false;
+        }
+    }
+
     public static Method getMethod(Class<?> clazz, String method, Class<?>... args) {
         try {
             return clazz.getMethod(method, args);