Merge pull request 'AntiNocom false flag reduction' (#234) from nocom into master

Reviewed-on: #234
Reviewed-by: YoyoNow <jwsteam@nidido.de>

SpigotCore_Main/src/de/steamwar/core/events/AntiNocom.java

@@ -27,12 +27,20 @@ import de.steamwar.techhider.ProtocolUtils;
 import de.steamwar.techhider.TechHider;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerQuitEvent;
 
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Function;
 
-public class AntiNocom {
+public class AntiNocom implements Listener {
+
+    private final Map<Player, Integer> flags = new ConcurrentHashMap<>();
 
     public AntiNocom() {
+        Bukkit.getServer().getPluginManager().registerEvents(this, Core.getInstance());
         TinyProtocol.instance.addFilter(blockDig, this::onDig);
 
         if(Core.getVersion() > 8) {
@@ -40,6 +48,11 @@ public class AntiNocom {
         }
     }
 
+    @EventHandler
+    public void onQuit(PlayerQuitEvent e) {
+        flags.remove(e.getPlayer());
+    }
+
     private void registerUseItem() {
         Class<?> useItem = Reflection.getClass("{nms.network.protocol.game}.PacketPlayInUseItem");
 
@@ -56,16 +69,7 @@ public class AntiNocom {
 
         TinyProtocol.instance.addFilter(useItem, (player, packet) -> {
             Object pos = getPosition.apply(packet);
-            int x = TechHider.blockPositionX.get(pos);
-            int z = TechHider.blockPositionZ.get(pos);
-
-            if(!player.getWorld().isChunkLoaded(ProtocolUtils.posToChunk(x), ProtocolUtils.posToChunk(z))) {
-                Bukkit.getScheduler().runTask(Core.getInstance(), () -> player.kickPlayer(null));
-                SWException.log(player.getName() + " kicked for using item on unloaded block (potential NoCom-DOS attack)", x + " " + z);
-                return null;
-            }
-
-            return packet;
+            return isValid(player, "UseItem", TechHider.blockPositionX.get(pos), TechHider.blockPositionZ.get(pos)) ? packet : null;
         });
     }
 
@@ -73,13 +77,20 @@ public class AntiNocom {
     private static final Reflection.FieldAccessor<?> digPosition = Reflection.getField(blockDig, TechHider.blockPosition, 0);
     private Object onDig(Player player, Object packet) {
         Object pos = digPosition.get(packet);
-        int x = TechHider.blockPositionX.get(pos);
-        int z = TechHider.blockPositionZ.get(pos);
-        if((x != 0 || z != 0) && !player.getWorld().isChunkLoaded(ProtocolUtils.posToChunk(x), ProtocolUtils.posToChunk(z))) {
-            Bukkit.getScheduler().runTask(Core.getInstance(), () -> player.kickPlayer(null));
-            SWException.log(player.getName() + " kicked for digging an unloaded block (potential NoCom-DOS attack)", x + " " + z);
-            return null;
+        return isValid(player, "Dig", TechHider.blockPositionX.get(pos), TechHider.blockPositionZ.get(pos)) ? packet : null;
+    }
+
+    private boolean isValid(Player player, String type, int x, int z) {
+        if((x == 0 && z == 0) || player.getWorld().isChunkLoaded(ProtocolUtils.posToChunk(x), ProtocolUtils.posToChunk(z)))
+            return true;
+
+        int amount = flags.compute(player, (p, a) -> a == null ? 1 : a+1);
+        if(amount % 8 == 0) {  // Only after 8 and every 8 to reduce false flags and spam
+            if(amount == 8)  // Schedule player kick only once
+                Bukkit.getScheduler().runTask(Core.getInstance(), () -> player.kickPlayer(null));
+
+            SWException.log(player.getName() + " kicked for potential NoCom-DOS attack", x + " " + z + " " + type + " " + amount);
         }
-        return packet;
+        return false;
     }
 }