Ensure that server operators are informed about incompatibility.

ProtocolLib/src/com/comphenix/protocol/events/ListeningWhitelist.java

@@ -86,6 +86,23 @@ public class ListeningWhitelist {
 	    return Objects.hashCode(priority, whitelist);
 	}
 
+	/**
+	 * Determine if any of the given IDs can be found in the whitelist.
+	 * @param whitelist - whitelist to test.
+	 * @param idList - list of packet IDs to find. 
+	 * @return TRUE if any of the packets in the list can be found in the whitelist, FALSE otherwise.
+	 */
+	public static boolean containsAny(ListeningWhitelist whitelist, int... idList) {
+		if (whitelist != null) {
+			for (int i = 0; i < idList.length; i++) {
+				if (whitelist.getWhitelist().contains(idList[i]))
+					return true;
+			}
+		}
+		
+		return false;
+	}
+	
 	@Override
 	public boolean equals(final Object obj){
 	    if(obj instanceof ListeningWhitelist){

ProtocolLib/src/com/comphenix/protocol/injector/NetworkFieldInjector.java

@@ -10,6 +10,9 @@ import java.util.concurrent.ConcurrentHashMap;
 
 import org.bukkit.entity.Player;
 
+import com.comphenix.protocol.Packets;
+import com.comphenix.protocol.events.ListeningWhitelist;
+import com.comphenix.protocol.events.PacketListener;
 import com.comphenix.protocol.reflect.FieldUtils;
 import com.comphenix.protocol.reflect.FuzzyReflection;
 import com.comphenix.protocol.reflect.StructureModifier;
@@ -83,11 +86,13 @@ class NetworkFieldInjector extends PlayerInjector {
 		}
 	}
 	
-
 	@Override
-	public boolean canInject() {
-		// Probably
-		return true;
+	public void checkListener(PacketListener listener) {
+		// Unfortunately, we don't support chunk packets
+		if (ListeningWhitelist.containsAny(listener.getSendingWhitelist(), 
+				Packets.Server.MAP_CHUNK, Packets.Server.MAP_CHUNK_BULK)) {
+			throw new IllegalStateException("The NETWORK_FIELD_INJECTOR hook doesn't support map chunk listeners.");
+		}
 	}
 	
 	@Override

ProtocolLib/src/com/comphenix/protocol/injector/NetworkObjectInjector.java

@@ -11,6 +11,10 @@ import java.util.Set;
 
 import org.bukkit.entity.Player;
 
+import com.comphenix.protocol.Packets;
+import com.comphenix.protocol.events.ListeningWhitelist;
+import com.comphenix.protocol.events.PacketListener;
+
 /**
  * Injection method that overrides the NetworkHandler itself, and it's sendPacket-method.
  * 
@@ -43,11 +47,12 @@ class NetworkObjectInjector extends PlayerInjector {
 	}
 	
 	@Override
-	public boolean canInject() {
-		// We only support 1.3.0 at the moment. Fixing it require us to
-		// add jMock, which would add another dependency.
-		return networkManager != null && 
-			   networkManagerField.getType().isInterface();
+	public void checkListener(PacketListener listener) {
+		// Unfortunately, we don't support chunk packets
+		if (ListeningWhitelist.containsAny(listener.getSendingWhitelist(), 
+				Packets.Server.MAP_CHUNK, Packets.Server.MAP_CHUNK_BULK)) {
+			throw new IllegalStateException("The NETWORK_FIELD_INJECTOR hook doesn't support map chunk listeners.");
+		}
 	}
 	
 	@Override

ProtocolLib/src/com/comphenix/protocol/injector/NetworkServerInjector.java

@@ -12,6 +12,7 @@ import net.sf.cglib.proxy.MethodProxy;
 
 import org.bukkit.entity.Player;
 
+import com.comphenix.protocol.events.PacketListener;
 import com.comphenix.protocol.reflect.FieldUtils;
 import com.comphenix.protocol.reflect.FuzzyReflection;
 import com.comphenix.protocol.reflect.instances.CollectionGenerator;
@@ -66,6 +67,7 @@ public class NetworkServerInjector extends PlayerInjector {
 
 	@Override
 	public void injectManager() {
+		
 		if (serverHandlerRef == null)
 			throw new IllegalStateException("Cannot find server handler.");
 		// Don't inject twice
@@ -144,8 +146,7 @@ public class NetworkServerInjector extends PlayerInjector {
 	}
 	
 	@Override
-	public boolean canInject() {
-		// Probably always
-		return true;
+	public void checkListener(PacketListener listener) {
+		// We support everything
 	}
 }

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

@@ -74,7 +74,7 @@ public final class PacketFilterManager implements ProtocolManager {
 		NETWORK_MANAGER_OBJECT,
 		
 		/**
-		 * Override the server handler object. Versatile, but slow.
+		 * Override the server handler object. Versatile, but a tad slower.
 		 */
 		NETWORK_SERVER_OBJECT;
 	}
@@ -106,6 +106,9 @@ public final class PacketFilterManager implements ProtocolManager {
 	// The default class loader
 	private ClassLoader classLoader;
 	
+	// The last successful player hook
+	private PlayerInjector lastSuccessfulHook;
+	
 	// Error logger
 	private Logger logger;
 	
@@ -142,6 +145,13 @@ public final class PacketFilterManager implements ProtocolManager {
 	 */
 	public void setPlayerHook(PlayerInjectHooks playerHook) {
 		this.playerHook = playerHook;
+		
+		// Make sure the current listeners are compatible
+		if (lastSuccessfulHook != null) {
+			for (PacketListener listener : packetListeners) {
+				checkListener(listener);
+			}
+		}
 	}
 
 	public Logger getLogger() {
@@ -176,6 +186,9 @@ public final class PacketFilterManager implements ProtocolManager {
 			if (hasReceiving) {
 				recievedListeners.addListener(listener, receiving);
 				enablePacketFilters(ConnectionSide.CLIENT_SIDE, receiving.getWhitelist());
+				
+				// We don't know if we've hooked any players yet
+				checkListener(listener);
 			}
 			
 			// Inform our injected hooks
@@ -183,6 +196,20 @@ public final class PacketFilterManager implements ProtocolManager {
 		}
 	}
 	
+	/**
+	 * Determine if a listener is valid or not.
+	 * @param listener - listener to check.
+	 * @throws IllegalStateException If the given listener's whitelist cannot be fulfilled.
+	 */
+	public void checkListener(PacketListener listener) {
+		try {
+			if (lastSuccessfulHook != null)
+				lastSuccessfulHook.checkListener(listener);
+		} catch (Exception e) {
+			throw new IllegalStateException("Registering listener " + PacketAdapter.getPluginName(listener) + " failed", e);
+		}
+	}
+	
 	@Override
 	public void removePacketListener(PacketListener listener) {
 		if (listener == null)
@@ -367,15 +394,11 @@ public final class PacketFilterManager implements ProtocolManager {
 	/**
 	 * Used to construct a player hook.
 	 * @param player - the player to hook.
+	 * @param hook - the hook type.
 	 * @return A new player hoook
 	 * @throws IllegalAccessException Unable to do our reflection magic.
 	 */
-	protected PlayerInjector getPlayerHookInstance(Player player) throws IllegalAccessException {
-		return getHookInstance(player, playerHook);
-	}
-	
-	// Helper
-	private PlayerInjector getHookInstance(Player player, PlayerInjectHooks hook) throws IllegalAccessException {
+	protected PlayerInjector getHookInstance(Player player, PlayerInjectHooks hook) throws IllegalAccessException {
 		// Construct the correct player hook
 		switch (hook) {
 		case NETWORK_HANDLER_FIELDS: 
@@ -394,23 +417,45 @@ public final class PacketFilterManager implements ProtocolManager {
 	 * @param player - player to hook.
 	 */
 	protected void injectPlayer(Player player) {
+		
+		PlayerInjector injector = null;
+		PlayerInjectHooks currentHook = playerHook;
+		boolean firstPlayer = lastSuccessfulHook == null;
+		
 		// Don't inject if the class has closed
 		if (!hasClosed && player != null && !playerInjection.containsKey(player)) {
+			while (true) {
 				try {
-				PlayerInjector injector = getPlayerHookInstance(player);
-
+					injector = getHookInstance(player, currentHook);
 					injector.injectManager();
 					playerInjection.put(player, injector);
 					connectionLookup.put(injector.getInputStream(false), player);
+					break;
 					
-			} catch (IllegalAccessException e) {
+				} catch (Exception e) {
 					// Mark this injection attempt as a failure
+					logger.log(Level.SEVERE, "Player hook " + currentHook.toString() + " failed.", e);
+					
+					if (currentHook.ordinal() > 0) {
+						// Choose the previous player hook type
+						currentHook = PlayerInjectHooks.values()[currentHook.ordinal() - 1];
+						logger.log(Level.INFO, "Switching to " + currentHook.toString() + " instead.");
+					} else {
+						// UTTER FAILURE
 						playerInjection.put(player, null);
-				logger.log(Level.SEVERE, "Unable to access fields.", e);
+						return;
 					}
 				}
 			}
 			
+			// Update values
+			if (injector != null)
+				lastSuccessfulHook = injector;
+			if (currentHook != playerHook || firstPlayer) 
+				setPlayerHook(currentHook);
+		}
+	}
+	
 	/**
 	 * Register this protocol manager on Bukkit.
 	 * @param manager - Bukkit plugin manager that provides player join/leave events.

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

@@ -31,6 +31,7 @@ import org.bukkit.entity.Player;
 
 import com.comphenix.protocol.events.PacketContainer;
 import com.comphenix.protocol.events.PacketEvent;
+import com.comphenix.protocol.events.PacketListener;
 import com.comphenix.protocol.reflect.FieldUtils;
 import com.comphenix.protocol.reflect.FuzzyReflection;
 import com.comphenix.protocol.reflect.StructureModifier;
@@ -205,10 +206,12 @@ abstract class PlayerInjector {
 	public abstract void cleanupAll();
 	
 	/**
-	 * Determine if we actually can inject.
-	 * @return TRUE if this injector is compatible with the current CraftBukkit version, FALSE otherwise.
+	 * Invoked before a new listener is registered.
+	 * <p>
+	 * The player injector should throw an exception if this listener cannot be properly supplied with packet events. 
+	 * @param listener - the listener that is about to be registered.
 	 */
-	public abstract boolean canInject();
+	public abstract void checkListener(PacketListener listener);
 	
 	/**
 	 * Allows a packet to be recieved by the listeners.