WIP anti cheat

Signed-off-by: Lixfel <agga-games@gmx.de>

FightSystem_Core/src/de/steamwar/fightsystem/FightSystem.java

@@ -93,6 +93,7 @@ public class FightSystem extends JavaPlugin {
         new ClickAnalyzer();
         new HotbarKit.HotbarKitListener();
         new OneShotStateDependent(ArenaMode.All, FightState.PreSchemSetup, () -> Fight.playSound(SWSound.BLOCK_NOTE_PLING.getSound(), 100.0f, 2.0f));
+        new AntiCheat();
 
         new EnterHandler();
         techHider = new TechHiderWrapper();

FightSystem_Core/src/de/steamwar/fightsystem/listener/AntiCheat.java

@@ -0,0 +1,118 @@
+/*
+    This file is a part of the SteamWar software.
+
+    Copyright (C) 2022  SteamWar.de-Serverteam
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.steamwar.fightsystem.listener;
+
+import com.comphenix.tinyprotocol.Reflection;
+import com.comphenix.tinyprotocol.TinyProtocol;
+import de.steamwar.fightsystem.FightSystem;
+import de.steamwar.sql.SWException;
+import de.steamwar.techhider.ProtocolUtils;
+import de.steamwar.techhider.TechHider;
+import org.bukkit.Bukkit;
+import org.bukkit.Location;
+import org.bukkit.entity.Player;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.logging.Level;
+
+public class AntiCheat {
+
+    public AntiCheat() {
+        TinyProtocol.instance.addFilter(teleport, this::onTeleport);
+        TinyProtocol.instance.addFilter(position, this::onMove);
+        TinyProtocol.instance.addFilter(positionLook, this::onMove);
+        TinyProtocol.instance.addFilter(blockDig, this::onDig);
+    }
+
+    private static final Class<?> flying = Reflection.getClass("{nms.network.protocol.game}.PacketPlayInFlying");
+    private static final Reflection.FieldAccessor<Double> moveX = Reflection.getField(flying, double.class, 0);
+    private static final Reflection.FieldAccessor<Double> moveY = Reflection.getField(flying, double.class, 1);
+    private static final Reflection.FieldAccessor<Double> moveZ = Reflection.getField(flying, double.class, 2);
+    private static final Class<?> position = Reflection.getClass("{nms.network.protocol.game}.PacketPlayInFlying$PacketPlayInPosition");
+    private static final Class<?> positionLook = Reflection.getClass("{nms.network.protocol.game}.PacketPlayInFlying$PacketPlayInPositionLook");
+
+    private static final Class<?> teleport = Reflection.getClass("{nms.network.protocol.game}.PacketPlayOutPosition");
+    private static final Reflection.FieldAccessor<Double> tpX = Reflection.getField(teleport, double.class, 0);
+    private static final Reflection.FieldAccessor<Double> tpY = Reflection.getField(teleport, double.class, 1);
+    private static final Reflection.FieldAccessor<Double> tpZ = Reflection.getField(teleport, double.class, 2);
+
+    private final ConcurrentHashMap<Player, Movement> lastMovement = new ConcurrentHashMap<>();
+    private Object onTeleport(Player player, Object packet) {
+        //TODO Possible false flag through crouching into forbidden area?
+        //TODO circumvention through fast consecutive movements? (checks are synchronous)
+        //TODO uncertainty through moving pistons/desync etc.? (slow limit with timer to check for occurances?)
+        //TODO: Clearing with movement events?
+        Movement last = lastMovement.get(player);
+        if(last != null && tpX.get(packet) == last.x && tpY.get(packet) == last.y && tpZ.get(packet) == last.z) {
+            FightSystem.getPlugin().getLogger().log(Level.INFO, player.getName() + " was backported after small movement");
+        }
+        return packet;
+    }
+
+    private Object onMove(Player player, Object packet) {
+        //TODO Idee: Messung kleiner Movements, bei nächstem Movement mit folgendem Teleport für illegal movement trigger
+        Location location = player.getLocation();
+        double x = moveX.get(packet);
+        double dx = x - location.getX();
+        double y = moveY.get(packet);
+        double dy = x - location.getY();
+        double z = moveZ.get(packet);
+        double dz = z - location.getZ();
+        double lSqared = dx*dx + dy*dy + dz*dz;
+        lastMovement.compute(player, (p, previous) -> {
+            if(lSqared <= 0.00390625) {
+                return new Movement(x, y, z);
+            } else if(previous != null && previous.last) {
+                previous.last = false;
+                return previous;
+            }
+            return null;
+        });
+        return packet;
+    }
+
+    private static final Class<?> blockDig = Reflection.getClass("{nms.network.protocol.game}.PacketPlayInBlockDig");
+    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(!player.getWorld().isChunkLoaded(ProtocolUtils.posToChunk(x), ProtocolUtils.posToChunk(z))) {
+            Bukkit.getScheduler().runTask(FightSystem.getPlugin(), () -> player.kickPlayer(null));
+            SWException.log(player.getName() + " tried to dig an unloaded block", "");
+            return null;
+        }
+        return packet;
+    }
+
+    private static class Movement {
+        private final double x;
+        private final double y;
+        private final double z;
+        private boolean last;
+
+        private Movement(double x, double y, double z) {
+            this.x = x;
+            this.y = y;
+            this.z = z;
+            last = true;
+        }
+    }
+}