Netty handler tidy

bukkit/src/main/java/us/myles/ViaVersion/bukkit/handlers/BukkitDecodeHandler.java

@@ -3,19 +3,15 @@ package us.myles.ViaVersion.bukkit.handlers;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.ByteToMessageDecoder;
-import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.bukkit.util.NMSUtil;
-import us.myles.ViaVersion.exception.CancelException;
+import us.myles.ViaVersion.exception.CancelDecoderException;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.lang.reflect.InvocationTargetException;
 import java.util.List;
 
 public class BukkitDecodeHandler extends ByteToMessageDecoder {
-
     private final ByteToMessageDecoder minecraftDecoder;
     private final UserConnection info;
 
@@ -26,64 +22,40 @@ public class BukkitDecodeHandler extends ByteToMessageDecoder {
 
     @Override
     protected void decode(ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> list) throws Exception {
-        // use transformers
+        if (!info.checkIncomingPacket()) {
-        if (bytebuf.readableBytes() > 0) {
+            bytebuf.clear(); // Don't accumulate
-            // Ignore if pending disconnect
+            throw CancelDecoderException.generate(null);
-            if (info.isPendingDisconnect()) {
-                return;
-            }
-            // Increment received
-            boolean second = info.incrementReceived();
-            // Check PPS
-            if (second) {
-                if (info.handlePPS())
-                    return;
         }
 
-            if (info.isActive()) {
+        ByteBuf draft = null;
-                // Handle ID
-                int id = Type.VAR_INT.read(bytebuf);
-                // Transform
-                ByteBuf newPacket = ctx.alloc().buffer();
         try {
-                    if (id == PacketWrapper.PASSTHROUGH_ID) {
+            if (info.shouldTransformPacket()) {
-                        newPacket.writeBytes(bytebuf);
+                draft = ctx.alloc().buffer().writeBytes(bytebuf);
-                    } else {
+                info.transformIncoming(draft, CancelDecoderException::generate);
-                        PacketWrapper wrapper = new PacketWrapper(id, bytebuf, info);
-                        ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                        protInfo.getPipeline().transform(Direction.INCOMING, protInfo.getState(), wrapper);
-                        wrapper.writeToBuffer(newPacket);
             }
 
-                    bytebuf.clear();
-                    bytebuf = newPacket;
-                } catch (Exception e) {
-                    // Clear Buffer
-                    bytebuf.clear();
-                    // Release Packet, be free!
-                    newPacket.release();
-                    throw e;
-                }
-            }
-
-            // call minecraft decoder
             try {
-                list.addAll(PipelineUtil.callDecode(this.minecraftDecoder, ctx, bytebuf));
+                list.addAll(PipelineUtil.callDecode(this.minecraftDecoder, ctx, draft == null ? bytebuf : draft));
             } catch (InvocationTargetException e) {
                 if (e.getCause() instanceof Exception) {
                     throw (Exception) e.getCause();
+                } else if (e.getCause() instanceof Error) {
+                    throw (Error) e.getCause();
+                }
             }
         } finally {
-                if (info.isActive()) {
+            if (draft != null) {
-                    bytebuf.release();
+                draft.release();
-                }
             }
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (PipelineUtil.containsCause(cause, CancelDecoderException.class)) return; // ProtocolLib compat
         super.exceptionCaught(ctx, cause);
+        if (!NMSUtil.isDebugPropertySet()) {
+            cause.printStackTrace(); // Print if CB doesn't already do it
+        }
     }
 }

bukkit/src/main/java/us/myles/ViaVersion/bukkit/handlers/BukkitEncodeHandler.java

@@ -3,22 +3,18 @@ package us.myles.ViaVersion.bukkit.handlers;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToByteEncoder;
-import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
 import us.myles.ViaVersion.bukkit.util.NMSUtil;
-import us.myles.ViaVersion.exception.CancelException;
+import us.myles.ViaVersion.exception.CancelEncoderException;
 import us.myles.ViaVersion.handlers.ChannelHandlerContextWrapper;
 import us.myles.ViaVersion.handlers.ViaHandler;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 
 public class BukkitEncodeHandler extends MessageToByteEncoder implements ViaHandler {
-    private static Field versionField = null;
+    private static Field versionField;
 
     static {
         try {
@@ -51,6 +47,8 @@ public class BukkitEncodeHandler extends MessageToByteEncoder implements ViaHand
             } catch (InvocationTargetException e) {
                 if (e.getCause() instanceof Exception) {
                     throw (Exception) e.getCause();
+                } else if (e.getCause() instanceof Error) {
+                    throw (Error) e.getCause();
                 }
             }
         }
@@ -59,35 +57,17 @@ public class BukkitEncodeHandler extends MessageToByteEncoder implements ViaHand
     }
 
     public void transform(ByteBuf bytebuf) throws Exception {
-        if (bytebuf.readableBytes() == 0) {
+        info.checkOutgoingPacket();
-            return; // Someone Already Decoded It!
+        if (!info.shouldTransformPacket()) return;
-        }
+        info.transformOutgoing(bytebuf, CancelEncoderException::generate);
-        // Increment sent
-        info.incrementSent();
-        if (info.isActive()) {
-            // Handle ID
-            int id = Type.VAR_INT.read(bytebuf);
-            // Transform
-            ByteBuf oldPacket = bytebuf.copy();
-            bytebuf.clear();
-
-            try {
-                PacketWrapper wrapper = new PacketWrapper(id, oldPacket, info);
-                ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                protInfo.getPipeline().transform(Direction.OUTGOING, protInfo.getState(), wrapper);
-                wrapper.writeToBuffer(bytebuf);
-            } catch (Exception e) {
-                bytebuf.clear();
-                throw e;
-            } finally {
-                oldPacket.release();
-            }
-        }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (PipelineUtil.containsCause(cause, CancelEncoderException.class)) return; // ProtocolLib compat
         super.exceptionCaught(ctx, cause);
+        if (!NMSUtil.isDebugPropertySet()) {
+            cause.printStackTrace(); // Print if CB doesn't already do it
+        }
     }
 }

bukkit/src/main/java/us/myles/ViaVersion/bukkit/util/NMSUtil.java

@@ -5,6 +5,17 @@ import org.bukkit.Bukkit;
 public class NMSUtil {
     private static final String BASE = Bukkit.getServer().getClass().getPackage().getName();
     private static final String NMS = BASE.replace("org.bukkit.craftbukkit", "net.minecraft.server");
+    private static final boolean DEBUG_PROPERTY = loadDebugProperty();
+
+    private static boolean loadDebugProperty() {
+        try {
+            Class<?> serverClass = nms("MinecraftServer");
+            Object server = serverClass.getDeclaredMethod("getServer").invoke(null);
+            return (boolean) serverClass.getMethod("isDebugging").invoke(server);
+        } catch (ReflectiveOperationException e) {
+            return false;
+        }
+    }
 
     public static Class<?> nms(String className) throws ClassNotFoundException {
         return Class.forName(NMS + "." + className);
@@ -17,4 +28,11 @@ public class NMSUtil {
     public static String getVersion() {
         return BASE.substring(BASE.lastIndexOf('.') + 1);
     }
+
+    /**
+     * @return true if debug=true is set in the server.properties (added by CB)
+     */
+    public static boolean isDebugPropertySet() {
+        return DEBUG_PROPERTY;
+    }
 }

bungee/src/main/java/us/myles/ViaVersion/bungee/handlers/BungeeDecodeHandler.java

@@ -4,19 +4,13 @@ import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToMessageDecoder;
-import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.exception.CancelDecoderException;
-import us.myles.ViaVersion.exception.CancelException;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
-import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.util.List;
 
 @ChannelHandler.Sharable
 public class BungeeDecodeHandler extends MessageToMessageDecoder<ByteBuf> {
-
     private final UserConnection info;
 
     public BungeeDecodeHandler(UserConnection info) {
@@ -25,55 +19,24 @@ public class BungeeDecodeHandler extends MessageToMessageDecoder<ByteBuf> {
 
     @Override
     protected void decode(final ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> out) throws Exception {
-        // use transformers
+        if (!info.checkIncomingPacket()) throw CancelDecoderException.generate(null);
-        if (bytebuf.readableBytes() > 0) {
+        if (!info.shouldTransformPacket()) {
-            // Ignore if pending disconnect
+            out.add(bytebuf.retain());
-            if (info.isPendingDisconnect()) {
-                return;
-            }
-            // Increment received
-            boolean second = info.incrementReceived();
-            // Check PPS
-            if (second) {
-                if (info.handlePPS())
             return;
         }
 
-            if (info.isActive()) {
+        ByteBuf draft = ctx.alloc().buffer().writeBytes(bytebuf);
-                // Handle ID
-                int id = Type.VAR_INT.read(bytebuf);
-                // Transform
-                ByteBuf newPacket = ctx.alloc().buffer();
         try {
-                    if (id == PacketWrapper.PASSTHROUGH_ID) {
+            info.transformIncoming(draft, CancelDecoderException::generate);
-                        newPacket.writeBytes(bytebuf);
+            out.add(draft.retain());
-                    } else {
+        } finally {
-                        PacketWrapper wrapper = new PacketWrapper(id, bytebuf, info);
+            draft.release();
-                        ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                        protInfo.getPipeline().transform(Direction.INCOMING, protInfo.getState(), wrapper);
-                        wrapper.writeToBuffer(newPacket);
-                    }
-
-                    bytebuf.clear();
-                    bytebuf = newPacket;
-                } catch (Throwable e) {
-                    // Clear Buffer
-                    bytebuf.clear();
-                    // Release Packet, be free!
-                    newPacket.release();
-                    throw e;
-                }
-            } else {
-                bytebuf.retain();
-            }
-
-            out.add(bytebuf);
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (cause instanceof CancelDecoderException) return;
         super.exceptionCaught(ctx, cause);
     }
 }

bungee/src/main/java/us/myles/ViaVersion/bungee/handlers/BungeeEncodeHandler.java

@@ -4,84 +4,80 @@ import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToMessageEncoder;
-import us.myles.ViaVersion.api.PacketWrapper;
-import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
 import us.myles.ViaVersion.bungee.util.BungeePipelineUtil;
-import us.myles.ViaVersion.exception.CancelException;
+import us.myles.ViaVersion.exception.CancelEncoderException;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
-import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.util.List;
 
 @ChannelHandler.Sharable
 public class BungeeEncodeHandler extends MessageToMessageEncoder<ByteBuf> {
     private final UserConnection info;
-    private boolean handledCompression = false;
+    private boolean handledCompression;
 
     public BungeeEncodeHandler(UserConnection info) {
         this.info = info;
     }
 
-
     @Override
     protected void encode(final ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> out) throws Exception {
-        if (bytebuf.readableBytes() == 0) {
+        info.checkOutgoingPacket();
-            throw Via.getManager().isDebug() ? new CancelException() : CancelException.CACHED;
+        if (!info.shouldTransformPacket()) {
+            out.add(bytebuf.retain());
+            return;
         }
+
+        ByteBuf draft = ctx.alloc().buffer().writeBytes(bytebuf);
+        try {
+            boolean needsCompress = handleCompressionOrder(ctx, draft);
+            info.transformOutgoing(draft, CancelEncoderException::generate);
+
+            if (needsCompress) {
+                recompress(ctx, draft);
+            }
+
+            out.add(draft.retain());
+        } finally {
+            draft.release();
+        }
+    }
+
+    private boolean handleCompressionOrder(ChannelHandlerContext ctx, ByteBuf draft) {
         boolean needsCompress = false;
         if (!handledCompression) {
             if (ctx.pipeline().names().indexOf("compress") > ctx.pipeline().names().indexOf("via-encoder")) {
                 // Need to decompress this packet due to bad order
-                bytebuf = BungeePipelineUtil.decompress(ctx, bytebuf);
+                ByteBuf decompressed = BungeePipelineUtil.decompress(ctx, draft);
-                ChannelHandler encoder = ctx.pipeline().get("via-decoder");
+                try {
-                ChannelHandler decoder = ctx.pipeline().get("via-encoder");
+                    draft.clear().writeBytes(decompressed);
-                ctx.pipeline().remove(encoder);
+                } finally {
-                ctx.pipeline().remove(decoder);
+                    decompressed.release();
-                ctx.pipeline().addAfter("decompress", "via-decoder", encoder);
+                }
-                ctx.pipeline().addAfter("compress", "via-encoder", decoder);
+                ChannelHandler dec = ctx.pipeline().get("via-decoder");
+                ChannelHandler enc = ctx.pipeline().get("via-encoder");
+                ctx.pipeline().remove(dec);
+                ctx.pipeline().remove(enc);
+                ctx.pipeline().addAfter("decompress", "via-decoder", dec);
+                ctx.pipeline().addAfter("compress", "via-encoder", enc);
                 needsCompress = true;
                 handledCompression = true;
             }
         }
-        // Increment sent
+        return needsCompress;
-        info.incrementSent();
+    }
-
-        if (info.isActive()) {
-            // Handle ID
-            int id = Type.VAR_INT.read(bytebuf);
-            // Transform
-            ByteBuf oldPacket = bytebuf.copy();
-            bytebuf.clear();
 
+    private void recompress(ChannelHandlerContext ctx, ByteBuf draft) {
+        ByteBuf compressed = BungeePipelineUtil.compress(ctx, draft);
         try {
-                PacketWrapper wrapper = new PacketWrapper(id, oldPacket, info);
+            draft.clear().writeBytes(compressed);
-                ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                protInfo.getPipeline().transform(Direction.OUTGOING, protInfo.getState(), wrapper);
-                wrapper.writeToBuffer(bytebuf);
-            } catch (Throwable e) {
-                bytebuf.clear();
-                throw e;
         } finally {
-                oldPacket.release();
+            compressed.release();
-            }
-        }
-
-        if (needsCompress) {
-            ByteBuf old = bytebuf;
-            bytebuf = BungeePipelineUtil.compress(ctx, bytebuf);
-            old.release();
-            out.add(bytebuf);
-        } else {
-            out.add(bytebuf.retain());
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (cause instanceof CancelEncoderException) return;
         super.exceptionCaught(ctx, cause);
     }
 }

common/src/main/java/us/myles/ViaVersion/api/data/UserConnection.java

@@ -11,6 +11,8 @@ import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.ViaVersionConfig;
 import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.exception.CancelException;
+import us.myles.ViaVersion.packets.Direction;
 import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.util.PipelineUtil;
 
@@ -18,6 +20,7 @@ import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Function;
 
 public class UserConnection {
     private static final AtomicLong IDS = new AtomicLong();
@@ -190,6 +193,8 @@ public class UserConnection {
                     channel.close(); // =)
                 }
             });
+        } else {
+            getChannel().close(); // Just disconnect, we don't know what the connection is
         }
     }
 
@@ -340,6 +345,81 @@ public class UserConnection {
         this.warnings = warnings;
     }
 
+    /**
+     * Monitors serverbound packets.
+     *
+     * @return false if this packet should be cancelled
+     */
+    public boolean checkIncomingPacket() {
+        // Ignore if pending disconnect
+        if (pendingDisconnect) return false;
+        // Increment received + Check PPS
+        return !incrementReceived() || !handlePPS();
+    }
+
+    /**
+     * Monitors clientbound packets.
+     */
+    public void checkOutgoingPacket() {
+        incrementSent();
+    }
+
+    /**
+     * Checks if packets needs transforming.
+     *
+     * @return if packets should be passed through
+     */
+    public boolean shouldTransformPacket() {
+        return active;
+    }
+
+    /**
+     * Transforms the clientbound packet contained in draft ByteBuf.
+     *
+     * @param draft          ByteBuf with packet id and packet contents
+     * @param cancelSupplier Function called with original CancelException for generating the Exception used when
+     *                       packet is cancelled
+     * @throws Exception when transforming failed or this packet is cancelled
+     */
+    public void transformOutgoing(ByteBuf draft, Function<Throwable, Exception> cancelSupplier) throws Exception {
+        if (!draft.isReadable()) return;
+        transform(draft, Direction.OUTGOING, cancelSupplier);
+    }
+
+    /**
+     * Transforms the serverbound packet contained in draft ByteBuf.
+     *
+     * @param draft          ByteBuf with packet id and packet contents
+     * @param cancelSupplier Function called with original CancelException for generating the Exception used when
+     *                       packet is cancelled
+     * @throws Exception when transforming failed or this packet is cancelled
+     */
+    public void transformIncoming(ByteBuf draft, Function<Throwable, Exception> cancelSupplier) throws Exception {
+        if (!draft.isReadable()) return;
+        transform(draft, Direction.INCOMING, cancelSupplier);
+    }
+
+    private void transform(ByteBuf draft, Direction direction, Function<Throwable, Exception> cancelSupplier) throws Exception {
+        int id = Type.VAR_INT.read(draft);
+        if (id == PacketWrapper.PASSTHROUGH_ID) return;
+
+        PacketWrapper wrapper = new PacketWrapper(id, draft, this);
+        ProtocolInfo protInfo = get(ProtocolInfo.class);
+        try {
+            protInfo.getPipeline().transform(direction, protInfo.getState(), wrapper);
+        } catch (CancelException ex) {
+            throw cancelSupplier.apply(ex);
+        }
+
+        ByteBuf transformed = draft.alloc().buffer();
+        try {
+            wrapper.writeToBuffer(transformed);
+            draft.clear().writeBytes(transformed);
+        } finally {
+            transformed.release();
+        }
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;

common/src/main/java/us/myles/ViaVersion/api/protocol/Protocol.java

@@ -435,7 +435,7 @@ public abstract class Protocol<C1 extends ClientboundPacketType, C2 extends Clie
         }
 
         if (packetWrapper.isCancelled()) {
-            throw Via.getManager().isDebug() ? new CancelException() : CancelException.CACHED;
+            throw CancelException.generate();
         }
     }
 

common/src/main/java/us/myles/ViaVersion/exception/CancelDecoderException.java

@@ -0,0 +1,42 @@
+package us.myles.ViaVersion.exception;
+
+import io.netty.handler.codec.DecoderException;
+import us.myles.ViaVersion.api.Via;
+
+/**
+ * Used for cancelling packets in decode handlers
+ */
+public class CancelDecoderException extends DecoderException {
+    public static final CancelDecoderException CACHED = new CancelDecoderException("CACHED") {
+        @Override
+        public synchronized Throwable fillInStackTrace() {
+            return this;
+        }
+    };
+
+    public CancelDecoderException() {
+        super();
+    }
+
+    public CancelDecoderException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public CancelDecoderException(String message) {
+        super(message);
+    }
+
+    public CancelDecoderException(Throwable cause) {
+        super(cause);
+    }
+
+    /**
+     * Returns a cached CancelDecoderException or a new instance when {@link us.myles.ViaVersion.ViaManager}#isDebug() is true
+     * @param cause cause for being used when a new instance is creeated
+     * @return a CancelDecoderException instance
+     */
+    public static CancelDecoderException generate(Throwable cause) {
+        if (Via.getManager().isDebug()) return new CancelDecoderException(cause);
+        return CACHED;
+    }
+}

common/src/main/java/us/myles/ViaVersion/exception/CancelEncoderException.java

@@ -0,0 +1,42 @@
+package us.myles.ViaVersion.exception;
+
+import io.netty.handler.codec.EncoderException;
+import us.myles.ViaVersion.api.Via;
+
+/**
+ * Used for cancelling packets in encode handlers
+ */
+public class CancelEncoderException extends EncoderException {
+    public static final CancelEncoderException CACHED = new CancelEncoderException("CACHED") {
+        @Override
+        public synchronized Throwable fillInStackTrace() {
+            return this;
+        }
+    };
+
+    public CancelEncoderException() {
+        super();
+    }
+
+    public CancelEncoderException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public CancelEncoderException(String message) {
+        super(message);
+    }
+
+    public CancelEncoderException(Throwable cause) {
+        super(cause);
+    }
+
+    /**
+     * Returns a cached CancelEncoderException or a new instance when {@link us.myles.ViaVersion.ViaManager}#isDebug() is true
+     * @param cause cause for being used when a new instance is creeated
+     * @return a CancelEncoderException instance
+     */
+    public static CancelEncoderException generate(Throwable cause) {
+        if (Via.getManager().isDebug()) return new CancelEncoderException(cause);
+        return CACHED;
+    }
+}

common/src/main/java/us/myles/ViaVersion/exception/CancelException.java

@@ -1,5 +1,10 @@
 package us.myles.ViaVersion.exception;
 
+import us.myles.ViaVersion.api.Via;
+
+/**
+ * Used for cancelling packets
+ */
 public class CancelException extends Exception {
     public static final CancelException CACHED = new CancelException("Cached - Enable /viaver debug to not use cached exception") {
         @Override
@@ -26,4 +31,13 @@ public class CancelException extends Exception {
     public CancelException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
         super(message, cause, enableSuppression, writableStackTrace);
     }
+
+    /**
+     * Returns a cached CancelException or a new instance when {@link us.myles.ViaVersion.ViaManager}#isDebug() is true
+     * @return a CancelException instance
+     */
+    public static CancelException generate() {
+        if (Via.getManager().isDebug()) return new CancelException();
+        return CACHED;
+    }
 }

common/src/main/java/us/myles/ViaVersion/handlers/ViaHandler.java

@@ -4,8 +4,8 @@ import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 
 public interface ViaHandler {
-    public void transform(ByteBuf bytebuf) throws Exception;
+    void transform(ByteBuf bytebuf) throws Exception;
 
-    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception;
+    void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception;
 
 }

sponge/src/main/java/us/myles/ViaVersion/sponge/handlers/SpongeDecodeHandler.java

@@ -3,12 +3,8 @@ package us.myles.ViaVersion.sponge.handlers;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.ByteToMessageDecoder;
-import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.exception.CancelDecoderException;
-import us.myles.ViaVersion.exception.CancelException;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.lang.reflect.InvocationTargetException;
@@ -26,64 +22,37 @@ public class SpongeDecodeHandler extends ByteToMessageDecoder {
 
     @Override
     protected void decode(ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> list) throws Exception {
-        // use transformers
+        if (!info.checkIncomingPacket()) {
-        if (bytebuf.readableBytes() > 0) {
+            bytebuf.clear(); // Don't accumulate
-            // Ignore if pending disconnect
+            throw CancelDecoderException.generate(null);
-            if (info.isPendingDisconnect()) {
-                return;
-            }
-            // Increment received
-            boolean second = info.incrementReceived();
-            // Check PPS
-            if (second) {
-                if (info.handlePPS())
-                    return;
         }
 
-            if (info.isActive()) {
+        ByteBuf draft = null;
-                // Handle ID
-                int id = Type.VAR_INT.read(bytebuf);
-                // Transform
-                ByteBuf newPacket = ctx.alloc().buffer();
         try {
-                    if (id == PacketWrapper.PASSTHROUGH_ID) {
+            if (info.shouldTransformPacket()) {
-                        newPacket.writeBytes(bytebuf);
+                draft = ctx.alloc().buffer().writeBytes(bytebuf);
-                    } else {
+                info.transformIncoming(draft, CancelDecoderException::generate);
-                        PacketWrapper wrapper = new PacketWrapper(id, bytebuf, info);
-                        ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                        protInfo.getPipeline().transform(Direction.INCOMING, protInfo.getState(), wrapper);
-                        wrapper.writeToBuffer(newPacket);
             }
 
-                    bytebuf.clear();
-                    bytebuf = newPacket;
-                } catch (Throwable e) {
-                    // Clear Buffer
-                    bytebuf.clear();
-                    // Release Packet, be free!
-                    newPacket.release();
-                    throw e;
-                }
-            }
-
-            // call minecraft decoder
             try {
-                list.addAll(PipelineUtil.callDecode(this.minecraftDecoder, ctx, bytebuf));
+                list.addAll(PipelineUtil.callDecode(this.minecraftDecoder, ctx, draft == null ? bytebuf : draft));
             } catch (InvocationTargetException e) {
                 if (e.getCause() instanceof Exception) {
                     throw (Exception) e.getCause();
+                } else if (e.getCause() instanceof Error) {
+                    throw (Error) e.getCause();
+                }
             }
         } finally {
-                if (info.isActive()) {
+            if (draft != null) {
-                    bytebuf.release();
+                draft.release();
-                }
             }
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (cause instanceof CancelDecoderException) return;
         super.exceptionCaught(ctx, cause);
     }
 }

sponge/src/main/java/us/myles/ViaVersion/sponge/handlers/SpongeEncodeHandler.java

@@ -3,69 +3,52 @@ package us.myles.ViaVersion.sponge.handlers;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToByteEncoder;
-import us.myles.ViaVersion.api.PacketWrapper;
-import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.exception.CancelEncoderException;
-import us.myles.ViaVersion.exception.CancelException;
+import us.myles.ViaVersion.handlers.ChannelHandlerContextWrapper;
-import us.myles.ViaVersion.packets.Direction;
+import us.myles.ViaVersion.handlers.ViaHandler;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.lang.reflect.InvocationTargetException;
 
-public class SpongeEncodeHandler extends MessageToByteEncoder {
+public class SpongeEncodeHandler extends MessageToByteEncoder<Object> implements ViaHandler {
     private final UserConnection info;
-    private final MessageToByteEncoder minecraftEncoder;
+    private final MessageToByteEncoder<?> minecraftEncoder;
 
-    public SpongeEncodeHandler(UserConnection info, MessageToByteEncoder minecraftEncoder) {
+    public SpongeEncodeHandler(UserConnection info, MessageToByteEncoder<?> minecraftEncoder) {
         this.info = info;
         this.minecraftEncoder = minecraftEncoder;
     }
 
-
     @Override
     protected void encode(final ChannelHandlerContext ctx, Object o, final ByteBuf bytebuf) throws Exception {
         // handle the packet type
         if (!(o instanceof ByteBuf)) {
             // call minecraft encoder
             try {
-                PipelineUtil.callEncode(this.minecraftEncoder, ctx, o, bytebuf);
+                PipelineUtil.callEncode(this.minecraftEncoder, new ChannelHandlerContextWrapper(ctx, this), o, bytebuf);
             } catch (InvocationTargetException e) {
                 if (e.getCause() instanceof Exception) {
                     throw (Exception) e.getCause();
+                } else if (e.getCause() instanceof Error) {
+                    throw (Error) e.getCause();
                 }
             }
         }
-        if (bytebuf.readableBytes() == 0) {
-            throw Via.getManager().isDebug() ? new CancelException() : CancelException.CACHED;
-        }
-        // Increment sent
-        info.incrementSent();
-        if (info.isActive()) {
-            // Handle ID
-            int id = Type.VAR_INT.read(bytebuf);
-            // Transform
-            ByteBuf oldPacket = bytebuf.copy();
-            bytebuf.clear();
 
-            try {
+        transform(bytebuf);
-                PacketWrapper wrapper = new PacketWrapper(id, oldPacket, info);
-                ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                protInfo.getPipeline().transform(Direction.OUTGOING, protInfo.getState(), wrapper);
-                wrapper.writeToBuffer(bytebuf);
-            } catch (Throwable e) {
-                bytebuf.clear();
-                throw e;
-            } finally {
-                oldPacket.release();
-            }
     }
+
+    @Override
+    public void transform(ByteBuf bytebuf) throws Exception {
+        info.checkOutgoingPacket();
+        if (!info.shouldTransformPacket()) return;
+        info.transformOutgoing(bytebuf, CancelEncoderException::generate);
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (cause instanceof CancelEncoderException) return;
         super.exceptionCaught(ctx, cause);
     }
 }

velocity/src/main/java/us/myles/ViaVersion/velocity/handlers/VelocityDecodeHandler.java

@@ -4,13 +4,8 @@ import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToMessageDecoder;
-import us.myles.ViaVersion.api.PacketWrapper;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.exception.CancelDecoderException;
-import us.myles.ViaVersion.exception.CancelException;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
-import us.myles.ViaVersion.util.PipelineUtil;
 
 import java.util.List;
 
@@ -24,54 +19,24 @@ public class VelocityDecodeHandler extends MessageToMessageDecoder<ByteBuf> {
 
     @Override
     protected void decode(ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> out) throws Exception {
-        // use transformers
+        if (!info.checkIncomingPacket()) throw CancelDecoderException.generate(null);
-        if (bytebuf.readableBytes() > 0) {
+        if (!info.shouldTransformPacket()) {
-            // Ignore if pending disconnect
+            out.add(bytebuf.retain());
-            if (info.isPendingDisconnect()) {
             return;
         }
-            // Increment received
+
-            boolean second = info.incrementReceived();
+        ByteBuf draft = ctx.alloc().buffer().writeBytes(bytebuf);
-            // Check PPS
-            if (second) {
-                if (info.handlePPS())
-                    return;
-            }
-            if (info.isActive()) {
-                // Handle ID
-                int id = Type.VAR_INT.read(bytebuf);
-                // Transform
-                ByteBuf newPacket = ctx.alloc().buffer();
         try {
-                    if (id == PacketWrapper.PASSTHROUGH_ID) {
+            info.transformIncoming(draft, CancelDecoderException::generate);
-                        newPacket.writeBytes(bytebuf);
+            out.add(draft.retain());
-                    } else {
+        } finally {
-                        PacketWrapper wrapper = new PacketWrapper(id, bytebuf, info);
+            draft.release();
-                        ProtocolInfo protInfo = info.get(ProtocolInfo.class);
-                        protInfo.getPipeline().transform(Direction.INCOMING, protInfo.getState(), wrapper);
-                        wrapper.writeToBuffer(newPacket);
-                    }
-
-                    bytebuf.clear();
-                    bytebuf = newPacket;
-                } catch (Throwable e) {
-                    // Clear Buffer
-                    bytebuf.clear();
-                    // Release Packet, be free!
-                    newPacket.release();
-                    throw e;
-                }
-            } else {
-                bytebuf.retain();
-            }
-
-            out.add(bytebuf);
         }
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (cause instanceof CancelDecoderException) return;
         super.exceptionCaught(ctx, cause);
     }
 }

velocity/src/main/java/us/myles/ViaVersion/velocity/handlers/VelocityEncodeHandler.java

@@ -6,15 +6,11 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToByteEncoder;
 import io.netty.handler.codec.MessageToMessageDecoder;
 import io.netty.handler.codec.MessageToMessageEncoder;
-import us.myles.ViaVersion.api.PacketWrapper;
-import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.type.Type;
+import us.myles.ViaVersion.exception.CancelEncoderException;
-import us.myles.ViaVersion.exception.CancelException;
-import us.myles.ViaVersion.packets.Direction;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.util.PipelineUtil;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.List;
 
 @ChannelHandler.Sharable
@@ -28,14 +24,38 @@ public class VelocityEncodeHandler extends MessageToMessageEncoder<ByteBuf> {
 
     @Override
     protected void encode(final ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> out) throws Exception {
-        if (bytebuf.readableBytes() == 0) {
+        info.checkOutgoingPacket();
-            throw Via.getManager().isDebug() ? new CancelException() : CancelException.CACHED;
+        if (!info.shouldTransformPacket()) {
+            out.add(bytebuf.retain());
+            return;
         }
+
+        ByteBuf draft = ctx.alloc().buffer().writeBytes(bytebuf);
+        try {
+            boolean needsCompress = handleCompressionOrder(ctx, draft);
+
+            info.transformOutgoing(draft, CancelEncoderException::generate);
+
+            if (needsCompress) {
+                recompress(ctx, draft);
+            }
+            out.add(draft.retain());
+        } finally {
+            draft.release();
+        }
+    }
+
+    private boolean handleCompressionOrder(ChannelHandlerContext ctx, ByteBuf draft) throws InvocationTargetException {
         boolean needsCompress = false;
         if (!handledCompression
                 && ctx.pipeline().names().indexOf("compression-encoder") > ctx.pipeline().names().indexOf("via-encoder")) {
             // Need to decompress this packet due to bad order
-            bytebuf = (ByteBuf) PipelineUtil.callDecode((MessageToMessageDecoder) ctx.pipeline().get("compression-decoder"), ctx, bytebuf).get(0);
+            ByteBuf decompressed = (ByteBuf) PipelineUtil.callDecode((MessageToMessageDecoder<?>) ctx.pipeline().get("compression-decoder"), ctx, draft).get(0);
+            try {
+                draft.clear().writeBytes(decompressed);
+            } finally {
+                decompressed.release();
+            }
             ChannelHandler encoder = ctx.pipeline().get("via-encoder");
             ChannelHandler decoder = ctx.pipeline().get("via-decoder");
             ctx.pipeline().remove(encoder);
@@ -44,51 +64,23 @@ public class VelocityEncodeHandler extends MessageToMessageEncoder<ByteBuf> {
             ctx.pipeline().addAfter("compression-decoder", "via-decoder", decoder);
             needsCompress = true;
             handledCompression = true;
-        } else {
-            bytebuf.retain();
         }
-        // Increment sent
+        return needsCompress;
-        info.incrementSent();
+    }
 
-
+    private void recompress(ChannelHandlerContext ctx, ByteBuf draft) throws InvocationTargetException {
-        if (info.isActive()) {
+        ByteBuf compressed = ctx.alloc().buffer();
-            // Handle ID
-            int id = Type.VAR_INT.read(bytebuf);
-            // Transform
-            ByteBuf newPacket = bytebuf.alloc().buffer();
         try {
-                PacketWrapper wrapper = new PacketWrapper(id, bytebuf, info);
+            PipelineUtil.callEncode((MessageToByteEncoder<?>) ctx.pipeline().get("compression-encoder"), ctx, draft, compressed);
-                ProtocolInfo protInfo = info.get(ProtocolInfo.class);
+            draft.clear().writeBytes(compressed);
-                protInfo.getPipeline().transform(Direction.OUTGOING, protInfo.getState(), wrapper);
-
-                wrapper.writeToBuffer(newPacket);
-
-                bytebuf.clear();
-                bytebuf.release();
-                bytebuf = newPacket;
-            } catch (Throwable e) {
-                bytebuf.clear();
-                bytebuf.release();
-                newPacket.release();
-                throw e;
-            }
-        }
-
-        if (needsCompress) {
-            ByteBuf old = bytebuf;
-            bytebuf = ctx.alloc().buffer();
-            try {
-                PipelineUtil.callEncode((MessageToByteEncoder) ctx.pipeline().get("compression-encoder"), ctx, old, bytebuf);
         } finally {
-                old.release();
+            compressed.release();
         }
     }
-        out.add(bytebuf);
-    }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
-        if (PipelineUtil.containsCause(cause, CancelException.class)) return;
+        if (cause instanceof CancelEncoderException) return;
         super.exceptionCaught(ctx, cause);
     }
 }