Added support for "post packet events".

NetworkMarker now contains a list of post listeners that are invoked 
(in no particular order) when a packet has been serialize and sent
to a player, OR, when it has been enqueued for processing by the 
server.

This works for both 1.7.2+ (Netty) and 1.6.4 and earlier, though the
1.6.4 version has a good deal more overhead.

ProtocolLib/src/main/java/com/comphenix/protocol/events/NetworkMarker.java

@@ -7,15 +7,18 @@ import java.nio.ByteBuffer;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.List;
 import java.util.PriorityQueue;
 
 import javax.annotation.Nonnull;
 
 import com.comphenix.protocol.PacketType;
+import com.comphenix.protocol.ProtocolManager;
 import com.comphenix.protocol.utility.ByteBufferInputStream;
 import com.comphenix.protocol.utility.MinecraftReflection;
 import com.comphenix.protocol.utility.StreamSerializer;
 import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
 import com.google.common.primitives.Ints;
 
 /**
@@ -48,6 +51,8 @@ public abstract class NetworkMarker {
 	
 	// Custom network handler
 	private PriorityQueue<PacketOutputHandler> outputHandlers;
+	// Sent listeners
+	private List<PacketPostListener> postListeners;
 	
 	// The input buffer
 	private ByteBuffer inputBuffer;
@@ -151,7 +156,6 @@ public abstract class NetworkMarker {
 	 * <p>
 	 * The data is exactly the same as in {@link #getInputBuffer()}. 
 	 * @see #getInputBuffer()
-	 * @param excludeHeader - whether or not to exclude the packet ID header.
 	 * @return The incoming serialized packet data as a stream, or NULL if the packet was transmitted locally.
 	 */
 	public DataInputStream getInputStream() {
@@ -252,6 +256,45 @@ public abstract class NetworkMarker {
 		}
 	}
 	
+	/**
+	 * Add a listener that is invoked after a packet has been successfully sent to the client, or received 
+	 * by the server. 
+	 * <p>
+	 * Received packets are not guarenteed to have been fully processed, but packets passed 
+	 * to {@link ProtocolManager#recieveClientPacket(Player, PacketContainer)} will be processed after the
+	 * current packet event.
+	 * <p>
+	 * Note that post listeners will be executed asynchronously off the main thread. They are not executed
+	 * in any defined order.
+	 * @param listener - the listener that will be invoked.
+	 * @return TRUE if it was added.
+	 */
+	public boolean addPostListener(PacketPostListener listener) {
+		if (postListeners == null)
+			postListeners = Lists.newArrayList();
+		return postListeners.add(listener);
+	}
+	
+	/**
+	 * Remove the first instance of the given listener.
+	 * @param listener - listener to remove.
+	 * @return TRUE if it was removed, FALSE otherwise.
+	 */
+	public boolean removePostListener(PacketPostListener listener) {
+		if (postListeners != null) {
+			return postListeners.remove(listener);
+		}
+		return false;
+	}
+	
+	/**
+	 * Retrieve an immutable view of all the listeners that will be invoked once the packet has been sent or received.
+	 * @return Every post packet listener. Never NULL.
+	 */
+	public List<PacketPostListener> getPostListeners() {
+		return postListeners != null ? Collections.unmodifiableList(postListeners) : Collections.<PacketPostListener>emptyList();
+	}
+	
 	/**
 	 * Ensure that the packet event is server side.
 	 */
@@ -304,6 +347,15 @@ public abstract class NetworkMarker {
 		return marker != null && !marker.getOutputHandlers().isEmpty();
 	}
 	
+	/**
+	 * Determine if the given marker has any post listeners.
+	 * @param marker - the marker to check.
+	 * @return TRUE if it does, FALSE otherwise.
+	 */
+	public static boolean hasPostListeners(NetworkMarker marker) {
+		return marker != null && !marker.getPostListeners().isEmpty();
+	}
+	
 	/**
 	 * Retrieve the byte buffer stored in the given marker.
 	 * @param marker - the marker.

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketEvent.java

@@ -70,6 +70,7 @@ public class PacketEvent extends EventObject implements Cancellable {
 	
 	// Whether or not a packet event is read only
 	private boolean readOnly;
+	private boolean filtered;
 	
 	/**
 	 * Use the static constructors to create instances of this event.
@@ -77,18 +78,20 @@ public class PacketEvent extends EventObject implements Cancellable {
 	 */
 	public PacketEvent(Object source) {
 		super(source);
+		this.filtered = true;
 	}
 
 	private PacketEvent(Object source, PacketContainer packet, Player player, boolean serverPacket) {
-		this(source, packet, null, player, serverPacket);
+		this(source, packet, null, player, serverPacket, true);
 	}
 	
-	private PacketEvent(Object source, PacketContainer packet, NetworkMarker marker, Player player, boolean serverPacket) {
+	private PacketEvent(Object source, PacketContainer packet, NetworkMarker marker, Player player, boolean serverPacket, boolean filtered) {
 		super(source);
 		this.packet = packet;
 		this.playerReference = new WeakReference<Player>(player);
 		this.networkMarker = marker;
 		this.serverPacket = serverPacket;
+		this.filtered = filtered;
 	}
 	
 	private PacketEvent(PacketEvent origial, AsyncMarker asyncMarker) {
@@ -97,6 +100,7 @@ public class PacketEvent extends EventObject implements Cancellable {
 		this.playerReference = origial.playerReference;
 		this.cancel = origial.cancel;
 		this.serverPacket = origial.serverPacket;
+		this.filtered = origial.filtered;
 		this.asyncMarker = asyncMarker;
 		this.asynchronous = true;
 	}
@@ -121,7 +125,22 @@ public class PacketEvent extends EventObject implements Cancellable {
 	 * @return The event.
 	 */
 	public static PacketEvent fromClient(Object source, PacketContainer packet, NetworkMarker marker, Player client) {
-		return new PacketEvent(source, packet, marker, client, false);
+		return new PacketEvent(source, packet, marker, client, false, true);
+	}
+	
+	/**
+	 * Creates an event representing a client packet transmission.
+	 * <p>
+	 * If <i>filtered</i> is FALSE, then this event is only processed by packet monitors.
+	 * @param source - the event source.
+	 * @param packet - the packet.
+	 * @param marker - the network marker.
+	 * @param client - the client that sent the packet.
+	 * @param filtered - whether or not this packet event is processed by every packet listener.
+	 * @return The event.
+	 */
+	public static PacketEvent fromClient(Object source, PacketContainer packet, NetworkMarker marker, Player client, boolean filtered) {
+		return new PacketEvent(source, packet, marker, client, false, filtered);
 	}
 	
 	/**
@@ -144,7 +163,22 @@ public class PacketEvent extends EventObject implements Cancellable {
 	 * @return The event.
 	 */
 	public static PacketEvent fromServer(Object source, PacketContainer packet, NetworkMarker marker, Player recipient) {
-		return new PacketEvent(source, packet, marker, recipient, true);
+		return new PacketEvent(source, packet, marker, recipient, true, true);
+	}
+	
+	/**
+	 * Creates an event representing a server packet transmission.
+	 * <p>
+	 * If <i>filtered</i> is FALSE, then this event is only processed by packet monitors.
+	 * @param source - the event source.
+	 * @param packet - the packet.
+	 * @param marker - the network marker.
+	 * @param recipient - the client that will receieve the packet.
+	 * @param filtered - whether or not this packet event is processed by every packet listener.
+	 * @return The event.
+	 */
+	public static PacketEvent fromServer(Object source, PacketContainer packet, NetworkMarker marker, Player recipient, boolean filtered) {
+		return new PacketEvent(source, packet, marker, recipient, true, filtered);
 	}
 	
 	/**
@@ -286,6 +320,16 @@ public class PacketEvent extends EventObject implements Cancellable {
 		return playerReference.get();
 	}
 	
+	/**
+	 * Determine if this packet is filtered by every packet listener.
+	 * <p>
+	 * If not, it will only be intercepted by monitor packets.
+	 * @return TRUE if it is, FALSE otherwise.
+	 */
+	public boolean isFiltered() {
+		return filtered;
+	}
+	
 	/**
 	 * Whether or not this packet was created by the server.
 	 * <p>

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketListener.java

@@ -20,7 +20,7 @@ package com.comphenix.protocol.events;
 import org.bukkit.plugin.Plugin;
 
 /**
- * Represents a listener that receives notifications when packets are sent or received.
+ * Represents a listener that receives notifications when packets are sending or being received.
  * <p>
  * Use {@link PacketAdapter} for a simple wrapper around this interface.
  * @author Kristian

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketOutputAdapter.java

@@ -4,7 +4,6 @@ import org.bukkit.plugin.Plugin;
 
 /**
  * Represents an adapter version of the output handler interface.
- * 
  * @author Kristian
  */
 public abstract class PacketOutputAdapter implements PacketOutputHandler {

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketPostAdapter.java

@@ -0,0 +1,22 @@
+package com.comphenix.protocol.events;
+
+import org.bukkit.plugin.Plugin;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Represents an adapter version of a post listener.
+ * @author Kristian
+ */
+public abstract class PacketPostAdapter implements PacketPostListener {
+	private Plugin plugin;
+	
+	public PacketPostAdapter(Plugin plugin) {
+		this.plugin = Preconditions.checkNotNull(plugin, "plugin cannot be NULL");
+	}
+
+	@Override
+	public Plugin getPlugin() {
+		return plugin;
+	}
+}

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketPostListener.java

@@ -0,0 +1,23 @@
+package com.comphenix.protocol.events;
+
+import org.bukkit.plugin.Plugin;
+
+/**
+ * Represents a packet listener that is invoked after a packet has been sent or received.
+ * @author Kristian
+ */
+public interface PacketPostListener {
+	/**
+	 * Retrieve the plugin this listener belongs to.
+	 * @return The assoicated plugin.
+	 */
+	public Plugin getPlugin();
+	
+	/**
+	 * Invoked after a packet has been sent or received.
+	 * <p>
+	 * Note that this is invoked asynchronously.
+	 * @param event - the packet event.
+	 */
+	public void onPostEvent(PacketEvent event);
+}

ProtocolLib/src/main/java/com/comphenix/protocol/injector/NetworkProcessor.java

@@ -0,0 +1,83 @@
+package com.comphenix.protocol.injector;
+
+import java.util.PriorityQueue;
+
+import com.comphenix.protocol.error.ErrorReporter;
+import com.comphenix.protocol.events.NetworkMarker;
+import com.comphenix.protocol.events.PacketEvent;
+import com.comphenix.protocol.events.PacketOutputHandler;
+import com.comphenix.protocol.events.PacketPostListener;
+
+/**
+ * Represents a processor for network markers.
+ * @author Kristian
+ */
+public class NetworkProcessor {
+	private ErrorReporter reporter;
+	
+	/**
+	 * Construct a new network processor.
+	 * @param reporter - the reporter.
+	 */
+	public NetworkProcessor(ErrorReporter reporter) {
+		this.reporter = reporter;
+	}
+	
+	/**
+	 * Process the serialized packet byte array with the given network marker.
+	 * @param event - current packet event.
+	 * @param marker - the network marker.
+	 * @param input - the input array.
+	 * @return The output array.
+	 */
+	public byte[] processOutput(PacketEvent event, NetworkMarker marker, final byte[] input) {
+		// Bit of a hack - but we need the performance
+		PriorityQueue<PacketOutputHandler> handlers = (PriorityQueue<PacketOutputHandler>) 
+			marker.getOutputHandlers();
+		byte[] output = input;
+		
+		// Let each handler prepare the actual output
+		while (!handlers.isEmpty()) {
+			PacketOutputHandler handler = handlers.poll();
+			
+			try {
+				byte[] changed = handler.handle(event, output);
+				
+				// Don't break just because a plugin returned NULL
+				if (changed != null) {
+					output = changed;
+				} else {
+					throw new IllegalStateException("Handler cannot return a NULL array.");
+				}
+			} catch (OutOfMemoryError e) {
+				throw e;
+			} catch (ThreadDeath e) {
+				throw e;
+			} catch (Throwable e) {
+				reporter.reportMinimal(handler.getPlugin(), "PacketOutputHandler.handle()", e);
+			}
+		}
+		return output;
+	}
+
+	/**
+	 * Invoke the post listeners, if any.
+	 * @param marker - the network marker, or NULL.
+	 */
+	public void invokePostListeners(PacketEvent event, NetworkMarker marker) {
+		if (NetworkMarker.hasPostListeners(marker)) {
+			// Invoke every sent listener
+			for (PacketPostListener listener : marker.getPostListeners()) {
+				try {
+					listener.onPostEvent(event);
+				} catch (OutOfMemoryError e) {
+					throw e;
+				} catch (ThreadDeath e) {
+					throw e;
+				} catch (Throwable e) {
+					reporter.reportMinimal(listener.getPlugin(), "SentListener.run()", e);
+				}
+			}
+		}
+	}
+}

ProtocolLib/src/main/java/com/comphenix/protocol/injector/PacketFilterManager.java

@@ -782,7 +782,7 @@ public final class PacketFilterManager implements ProtocolManager, ListenerInvok
 	
 		// Inform the MONITOR packets
 		if (!filters) {
-			PacketEvent event = PacketEvent.fromServer(this, packet, marker, receiver);
+			PacketEvent event = PacketEvent.fromServer(this, packet, marker, receiver, false);
 			
 			sendingListeners.invokePacketSending(
 					reporter, event, ListenerPriority.MONITOR);
@@ -832,7 +832,7 @@ public final class PacketFilterManager implements ProtocolManager, ListenerInvok
 			// Let the monitors know though
 			recievedListeners.invokePacketSending(
 					reporter, 
-					PacketEvent.fromClient(this, packet, marker, sender), 
+					PacketEvent.fromClient(this, packet, marker, sender, false), 
 					ListenerPriority.MONITOR);
 		}
 		

ProtocolLib/src/main/java/com/comphenix/protocol/injector/netty/ChannelInjector.java

@@ -3,7 +3,10 @@ package com.comphenix.protocol.injector.netty;
 import java.lang.reflect.InvocationTargetException;
 import java.net.Socket;
 import java.net.SocketAddress;
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.List;
+import java.util.ListIterator;
 import java.util.Map.Entry;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentMap;
@@ -13,6 +16,9 @@ import net.minecraft.util.io.netty.buffer.ByteBuf;
 import net.minecraft.util.io.netty.channel.Channel;
 import net.minecraft.util.io.netty.channel.ChannelHandler;
 import net.minecraft.util.io.netty.channel.ChannelHandlerContext;
+import net.minecraft.util.io.netty.channel.ChannelInboundHandler;
+import net.minecraft.util.io.netty.channel.ChannelInboundHandlerAdapter;
+import net.minecraft.util.io.netty.channel.ChannelPromise;
 import net.minecraft.util.io.netty.channel.socket.SocketChannel;
 import net.minecraft.util.io.netty.handler.codec.ByteToMessageDecoder;
 import net.minecraft.util.io.netty.handler.codec.MessageToByteEncoder;
@@ -31,7 +37,7 @@ import com.comphenix.protocol.error.ReportType;
 import com.comphenix.protocol.events.ConnectionSide;
 import com.comphenix.protocol.events.NetworkMarker;
 import com.comphenix.protocol.events.PacketEvent;
-import com.comphenix.protocol.events.PacketOutputHandler;
+import com.comphenix.protocol.injector.NetworkProcessor;
 import com.comphenix.protocol.injector.server.SocketInjector;
 import com.comphenix.protocol.reflect.FuzzyReflection;
 import com.comphenix.protocol.reflect.VolatileField;
@@ -94,6 +100,11 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 	 */
 	private PacketEvent currentEvent;
 	
+	/**
+	 * A packet event that should be processed by the write method.
+	 */
+	private PacketEvent finalEvent;
+	
 	/**
 	 * A flag set by the main thread to indiciate that a packet should not be processed.
 	 */
@@ -107,12 +118,17 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 	private ByteToMessageDecoder vanillaDecoder;
 	private MessageToByteEncoder<Object> vanillaEncoder;
 	
-	// Our extra handler
+	// Our extra handlers
 	private MessageToByteEncoder<Object> protocolEncoder;
+	private ChannelInboundHandler finishHandler;
+	private Deque<PacketEvent> finishQueue = new ArrayDeque<PacketEvent>();
 
 	// The channel listener
 	private ChannelListener channelListener;
 	
+	// Processing network markers
+	private NetworkProcessor processor;
+	
 	// Closed
 	private boolean injected;
 	private boolean closed;
@@ -131,6 +147,7 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 		this.originalChannel = Preconditions.checkNotNull(channel, "channel cannot be NULL");
 		this.channelListener = Preconditions.checkNotNull(channelListener, "channelListener cannot be NULL");
 		this.factory = Preconditions.checkNotNull(factory, "factory cannot be NULL");
+		this.processor = new NetworkProcessor(ProtocolLibrary.getErrorReporter());
 		
 		// Get the channel field
 		this.channelField = new VolatileField(
@@ -178,10 +195,27 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 				protected void encode(ChannelHandlerContext ctx, Object packet, ByteBuf output) throws Exception {
 					ChannelInjector.this.encode(ctx, packet, output);
 				}
+				
+				@Override
+				public void write(ChannelHandlerContext ctx, Object packet, ChannelPromise promise) throws Exception {
+					super.write(ctx, packet, promise);
+					ChannelInjector.this.finalWrite(ctx, packet, promise);
+				}
+			};
+			
+			// Intercept recieved packets
+			finishHandler = new ChannelInboundHandlerAdapter() {
+				@Override
+				public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
+					// Execute context first
+					ctx.fireChannelRead(msg);
+					ChannelInjector.this.finishRead(ctx, msg);
+				}
 			};
 			
 			// Insert our handlers - note that we effectively replace the vanilla encoder/decoder 
 			originalChannel.pipeline().addBefore("decoder", "protocol_lib_decoder", this);
+			originalChannel.pipeline().addBefore("protocol_lib_decoder", "protocol_lib_finish", finishHandler);
 			originalChannel.pipeline().addAfter("encoder", "protocol_lib_encoder", protocolEncoder);
 			
 			// Intercept all write methods
@@ -286,10 +320,10 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 	 * @throws Exception If anything went wrong.
 	 */
 	protected void encode(ChannelHandlerContext ctx, Object packet, ByteBuf output) throws Exception {
-		try {
+		NetworkMarker marker = null;
-			PacketEvent event = currentEvent;
+		PacketEvent event = currentEvent;
-			NetworkMarker marker = null;
 		
+		try {
 			// Skip every kind of non-filtered packet
 			if (!scheduleProcessPackets.get()) {
 				return;
@@ -323,15 +357,16 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 			if (packet != null && event != null && NetworkMarker.hasOutputHandlers(marker)) {
 				ByteBuf packetBuffer = ctx.alloc().buffer();
 				ENCODE_BUFFER.invoke(vanillaEncoder, ctx, packet, packetBuffer);
-				byte[] data = getBytes(packetBuffer);
 
-				for (PacketOutputHandler handler : marker.getOutputHandlers()) {
+				// Let each handler prepare the actual output
-					data = handler.handle(event, data);
+				byte[] data = processor.processOutput(event, marker, getBytes(packetBuffer));
-				}
 				
 				// Write the result
 				output.writeBytes(data);
 				packet = null;
+				
+				// Sent listeners?
+				finalEvent = event;
 				return;
 			}
 		} catch (Exception e) {
@@ -341,10 +376,29 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 			// Attempt to handle the packet nevertheless
 			if (packet != null) {
 				ENCODE_BUFFER.invoke(vanillaEncoder, ctx, packet, output);
+				finalEvent = event;
 			}
 		}
 	}
 
+	/**
+	 * Invoked when a packet has been written to the channel.
+	 * @param ctx - current context.
+	 * @param packet - the packet that has been written.
+	 * @param promise - a promise.
+	 */
+	protected void finalWrite(ChannelHandlerContext ctx, Object packet, ChannelPromise promise) {
+		PacketEvent event = finalEvent;
+		
+		if (event != null) {
+			// Necessary to prevent infinite loops
+			finalEvent = null;
+			currentEvent = null;
+			
+			processor.invokePostListeners(event, NetworkMarker.getNetworkMarker(event));
+		}
+	}
+
 	private void scheduleMainThread(final Object packetCopy) {
 		// Don't use BukkitExecutors for this - it has a bit of overhead
 		Bukkit.getScheduler().scheduleSyncDelayedTask(factory.getPlugin(), new Runnable() {
@@ -361,8 +415,11 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 		DECODE_BUFFER.invoke(vanillaDecoder, ctx, byteBuffer, packets);
 		
 		try {		
-			if (packets.size() > 0) {
+			// Reset queue
-				Object input = packets.get(0);
+			finishQueue.clear();
+			
+			for (ListIterator<Object> it = packets.listIterator(); it.hasNext(); ) {
+				Object input = it.next();
 				Class<?> packetClass = input.getClass();
 				NetworkMarker marker = null;
 				
@@ -377,10 +434,14 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 				
 				// Handle packet changes
 				if (output != null) {
-					if (output.isCancelled())
+					if (output.isCancelled()) {
-						packets.clear();
+						it.remove();
-					else if (output.getPacket().getHandle() != input)
+						continue;
-						packets.set(0, output.getPacket().getHandle());
+					} else if (output.getPacket().getHandle() != input) {
+						it.set(output.getPacket().getHandle());
+					}
+					
+					finishQueue.addLast(output);
 				}
 			}
 		} catch (Exception e) {
@@ -389,6 +450,24 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 		}
 	}
 	
+	/**
+	 * Invoked after our decoder.
+	 * @param ctx - current context.
+	 * @param msg - the current packet.
+	 */
+	protected void finishRead(ChannelHandlerContext ctx, Object msg) {
+		// Assume same order
+		PacketEvent event = finishQueue.pollFirst();
+		
+		if (event != null) {
+			NetworkMarker marker = NetworkMarker.getNetworkMarker(event);
+			
+			if (marker != null) {
+				processor.invokePostListeners(event, marker);
+			}
+		}
+	}
+	
 	/**
 	 * Invoked when we may need to handle the login packet.
 	 * @param packetClass - the packet class.
@@ -608,6 +687,7 @@ class ChannelInjector extends ByteToMessageDecoder implements Injector {
 					@Override
 					public Object call() throws Exception {
 						originalChannel.pipeline().remove(ChannelInjector.this);
+						originalChannel.pipeline().remove(finishHandler);
 						originalChannel.pipeline().remove(protocolEncoder);
 						return null;
 					}

ProtocolLib/src/main/java/com/comphenix/protocol/injector/packet/ReadPacketModifier.java

@@ -28,8 +28,10 @@ import com.comphenix.protocol.PacketType.Sender;
 import com.comphenix.protocol.error.ErrorReporter;
 import com.comphenix.protocol.error.Report;
 import com.comphenix.protocol.error.ReportType;
+import com.comphenix.protocol.events.NetworkMarker;
 import com.comphenix.protocol.events.PacketContainer;
 import com.comphenix.protocol.events.PacketEvent;
+import com.comphenix.protocol.injector.NetworkProcessor;
 import com.google.common.collect.MapMaker;
 
 import net.sf.cglib.proxy.MethodInterceptor;
@@ -47,6 +49,7 @@ class ReadPacketModifier implements MethodInterceptor {
 	
 	// Report errors
 	private ErrorReporter reporter;
+	private NetworkProcessor processor;
 	
 	// If this is a read packet data method
 	private boolean isReadPacketDataMethod;
@@ -58,6 +61,7 @@ class ReadPacketModifier implements MethodInterceptor {
 		this.packetID = packetID;
 		this.packetInjector = packetInjector;
 		this.reporter = reporter;
+		this.processor = new NetworkProcessor(reporter);
 		this.isReadPacketDataMethod = isReadPacketDataMethod;
 	}
 	
@@ -152,9 +156,14 @@ class ReadPacketModifier implements MethodInterceptor {
 					
 					if (event.isCancelled()) {
 						override.put(thisObj, CANCEL_MARKER);
+						return returnValue;
 					} else if (!objectEquals(thisObj, result)) {
 						override.put(thisObj, result);
 					}
+					
+					// This is fine - received packets are enqueued in any case
+					NetworkMarker marker = NetworkMarker.getNetworkMarker(event);
+					processor.invokePostListeners(event, marker);
 				}
 				
 			} catch (OutOfMemoryError e) {

ProtocolLib/src/main/java/com/comphenix/protocol/injector/packet/WritePacketModifier.java

@@ -30,6 +30,7 @@ import com.comphenix.protocol.error.ReportType;
 import com.comphenix.protocol.events.NetworkMarker;
 import com.comphenix.protocol.events.PacketEvent;
 import com.comphenix.protocol.events.PacketOutputHandler;
+import com.comphenix.protocol.injector.NetworkProcessor;
 import com.google.common.collect.MapMaker;
 
 import net.sf.cglib.proxy.MethodInterceptor;
@@ -55,12 +56,14 @@ public class WritePacketModifier implements MethodInterceptor {
 
 	// Report errors
 	private final ErrorReporter reporter;
+	private final NetworkProcessor processor;
 	
 	// Whether or not this represents the write method
 	private boolean isWriteMethod;
 	
 	public WritePacketModifier(ErrorReporter reporter,  boolean isWriteMethod) {
 		this.reporter = reporter;
+		this.processor = new NetworkProcessor(reporter);
 		this.isWriteMethod = isWriteMethod;
 	}
 
@@ -85,39 +88,24 @@ public class WritePacketModifier implements MethodInterceptor {
 		}
 		
 		if (isWriteMethod) {
-			PriorityQueue<PacketOutputHandler> handlers = (PriorityQueue<PacketOutputHandler>) 
-					information.marker.getOutputHandlers();
-			
 			// If every output handler has been removed - ignore everything
-			if (!handlers.isEmpty()) {
+			if (!information.marker.getOutputHandlers().isEmpty()) {
 				try {
 					DataOutput output = (DataOutput) args[0];
 
 					// First - we need the initial buffer
 					ByteArrayOutputStream outputBufferStream = new ByteArrayOutputStream();
 					proxy.invoke(information.proxyObject, new Object[] { new DataOutputStream(outputBufferStream) });
-					byte[] outputBuffer = outputBufferStream.toByteArray();
 					
 					// Let each handler prepare the actual output
-					while (!handlers.isEmpty()) {
+					byte[] outputBuffer = processor.processOutput(information.event, information.marker, 
-						PacketOutputHandler handler = handlers.poll();
+							outputBufferStream.toByteArray());
-						
-						try {
-							byte[] changed = handler.handle(information.event, outputBuffer);
-							
-							// Don't break just because a plugin returned NULL
-							if (changed != null) {
-								outputBuffer = changed;
-							} else {
-								throw new IllegalStateException("Handler cannot return a NULL array.");
-							}
-						} catch (Exception e) {
-							reporter.reportMinimal(handler.getPlugin(), "PacketOutputHandler.handle()", e);
-						}
-					}
 					
 					// Write that output to the network stream
 					output.write(outputBuffer);
+
+					// We're done
+					processor.invokePostListeners(information.event, information.marker);
 					return null;
 					
 				} catch (OutOfMemoryError e) {
@@ -131,6 +119,11 @@ public class WritePacketModifier implements MethodInterceptor {
 					);
 				}
 			}
+			
+			// Invoke this write method first
+			proxy.invoke(information.proxyObject, args);
+			processor.invokePostListeners(information.event, information.marker);
+			return null;
 		}
 		
 		// Default to the super method

ProtocolLib/src/main/java/com/comphenix/protocol/injector/player/PlayerInjector.java

@@ -636,7 +636,7 @@ public abstract class PlayerInjector implements SocketInjector {
 				marker = NetworkMarker.getNetworkMarker(event);
 
 				// See if we need to proxy the write method
-				if (result != null && NetworkMarker.hasOutputHandlers(marker)) {
+				if (result != null && (NetworkMarker.hasOutputHandlers(marker) || NetworkMarker.hasPostListeners(marker))) {
 					result = writePacketInterceptor.constructProxy(result, event, marker);
 				}
 				return result;