XeroAntiCheat v1.1.0 bug fixes

README.md

@@ -1,2 +1,10 @@
 # XeroAntiCheat
 
+Lightweight, accurate anti-cheat for Paper 1.21.x
+
+## Latest Updates (v1.1.0)
+
+- **ReachCheck**: Now measures distance to entity bounding box center instead of feet. Eliminates false negatives when attacking tall entities (horses, iron golems, withers). Also switched from `distance()` to `distanceSquared()` comparison, removing a `Math.sqrt()` from the hot path.
+- **AutoClickerCheck**: `checkPattern()` rewritten with zero-allocation two-pass iterator approach. Previously allocated two `ArrayList` objects on every combat click.
+- **TimerCheck**: Removed redundant blink detection from `check()` method. Blink detection is fully handled by the 5-tick scheduled task. `setLastMovePacketTime()` retained to feed the task.
+- **KillAuraCheck**: Removed unused `EntityEffect` import.

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.xeroth</groupId>
     <artifactId>xeroanticheat</artifactId>
-    <version>1.0.9</version>
+    <version>1.1.0</version>
     <packaging>jar</packaging>
 
     <name>XeroAntiCheat</name>

src/main/java/com/xeroth/xeroanticheat/checks/combat/AutoClickerCheck.java

@@ -5,9 +5,6 @@ import com.xeroth.xeroanticheat.check.Check;
 import com.xeroth.xeroanticheat.data.PlayerData;
 import org.bukkit.entity.Player;
 
-import java.util.ArrayList;
-import java.util.List;
-
 /**
  * AutoClickerCheck - Tracks CPS (clicks per second) over a 1-second sliding window.
  * 
@@ -54,35 +51,33 @@ public class AutoClickerCheck extends Check {
      * Check click pattern for suspiciously low variance
      */
     private void checkPattern(PlayerData data, Player player, double minVariance) {
-        List<Long> clicks = new ArrayList<>(data.getClickTimestamps());
+        if (data.getClickTimestamps().size() < 5) return;
 
-        if (clicks.size() < 5) return;
-        
-        // Calculate intervals between clicks
-        List<Long> intervals = new ArrayList<>();
-        for (int i = 0; i < clicks.size() - 1; i++) {
-            intervals.add(clicks.get(i) - clicks.get(i + 1));
-        }
-        
-        if (intervals.isEmpty()) return;
-        
-        // Calculate mean
         double sum = 0;
-        for (Long interval : intervals) {
+        int intervalCount = 0;
-            sum += interval;
+        Long prev = null;
+        for (Long ts : data.getClickTimestamps()) {
+            if (prev != null) {
+                sum += (prev - ts);
+                intervalCount++;
+            }
+            prev = ts;
         }
-        double mean = sum / intervals.size();
+        if (intervalCount == 0) return;
+        double mean = sum / intervalCount;
 
-        // Calculate variance
         double varianceSum = 0;
-        for (Long interval : intervals) {
+        prev = null;
-            double diff = interval - mean;
+        for (Long ts : data.getClickTimestamps()) {
-            varianceSum += diff * diff;
+            if (prev != null) {
+                double diff = (prev - ts) - mean;
+                varianceSum += diff * diff;
+            }
+            prev = ts;
         }
-        double variance = varianceSum / intervals.size();
-        double stdDev = Math.sqrt(variance);
 
-        // If variance is too low, flag (too perfect)
+        double stdDev = Math.sqrt(varianceSum / intervalCount);
+
         if (stdDev < minVariance && data.getCPS() > 10) {
             flag(data, player, 1.0);
         }

src/main/java/com/xeroth/xeroanticheat/checks/combat/KillAuraCheck.java

@@ -3,7 +3,6 @@ package com.xeroth.xeroanticheat.checks.combat;
 import com.xeroth.xeroanticheat.XeroAntiCheat;
 import com.xeroth.xeroanticheat.check.Check;
 import com.xeroth.xeroanticheat.data.PlayerData;
-import org.bukkit.EntityEffect;
 import org.bukkit.Location;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.Player;

src/main/java/com/xeroth/xeroanticheat/checks/combat/ReachCheck.java

@@ -60,12 +60,20 @@ public class ReachCheck extends Check {
         // Get player eye location
         Location eyeLoc = player.getEyeLocation();
         
-        // Get target location (center of entity hitbox)
+        // Use center of entity bounding box, not feet position.
-        Location targetLoc = target.getLocation();
+        // getLocation() returns feet; bounding box center is more accurate for tall entities.
+        org.bukkit.util.BoundingBox bb = target.getBoundingBox();
+        double targetX = (bb.getMinX() + bb.getMaxX()) / 2.0;
+        double targetY = (bb.getMinY() + bb.getMaxY()) / 2.0;
+        double targetZ = (bb.getMinZ() + bb.getMaxZ()) / 2.0;
         
-        // Calculate 3D distance
+        // Calculate 3D distance from player eye to entity center (no Location object needed)
-        double distance = eyeLoc.distance(targetLoc);
+        double dx = eyeLoc.getX() - targetX;
+        double dy = eyeLoc.getY() - targetY;
+        double dz = eyeLoc.getZ() - targetZ;
+        double distanceSquared = dx * dx + dy * dy + dz * dz;
         
-        return distance > maxReach;
+        double maxReachSquared = maxReach * maxReach;
+        return distanceSquared > maxReachSquared;
     }
 }

src/main/java/com/xeroth/xeroanticheat/checks/movement/TimerCheck.java

@@ -32,7 +32,6 @@ public class TimerCheck extends Check {
 
         // Get thresholds
         int maxPacketsPerSecond = getConfigInt("max_packets_per_second", 22);
-        long blinkThresholdMs = getConfigInt("blink_threshold_ms", 500);
 
         // If ProtocolLib is active, packet counting is handled by PacketListener
         if (plugin.isProtocolLibLoaded()) {
@@ -57,28 +56,6 @@ public class TimerCheck extends Check {
             flag(data, player, (data.getPacketsThisSecond() - maxPacketsPerSecond) * 0.5);
         }
         
-        // Check for blink (packet suppression)
-        long lastMoveTime = data.getLastMovePacketTime();
-        if (lastMoveTime > 0) {
-            long gap = now - lastMoveTime;
-            if (gap > blinkThresholdMs) {
-                // Check if player teleported during the gap
-                PlayerData.PositionSnapshot current = data.getLastPosition();
-                PlayerData.PositionSnapshot last = data.getSecondLastPosition();
-                if (current != null && last != null) {
-                    double dx = current.x() - last.x();
-                    double dy = current.y() - last.y();
-                    double dz = current.z() - last.z();
-                    double distance = Math.sqrt(dx*dx + dy*dy + dz*dz);
-                    
-                    // If teleported more than 10 blocks, likely blink
-                    if (distance > 10) {
-                        flag(data, player, 2.0);
-                    }
-                }
-            }
-        }
-        
         data.setLastMovePacketTime(now);
     }
 }

src/main/resources/plugin.yml

@@ -1,5 +1,5 @@
 name: XeroAntiCheat
-version: 1.0.9
+version: 1.1.0
 main: com.xeroth.xeroanticheat.XeroAntiCheat
 author: Xeroth
 description: Lightweight, accurate anti-cheat for Paper 1.21.x