Avoid sign duplication due to a bug in CraftBukkit.

The cancelled BlockPlaceEvent will lead to an extra sign being dropped,
while the item in hand stays. Odd enough, the cactus is removed before
the BlockPlaceEvent - need to check if a ticket exists for CraftBukkit
already...

NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/blockinteract/BlockInteractData.java

@@ -3,11 +3,15 @@ package fr.neatmonster.nocheatplus.checks.blockinteract;
 import java.util.HashMap;
 import java.util.Map;
 
+import org.bukkit.Material;
+import org.bukkit.block.Block;
 import org.bukkit.entity.Player;
+import org.bukkit.event.block.Action;
 
 import fr.neatmonster.nocheatplus.checks.access.ACheckData;
 import fr.neatmonster.nocheatplus.checks.access.CheckDataFactory;
 import fr.neatmonster.nocheatplus.checks.access.ICheckData;
+import fr.neatmonster.nocheatplus.utilities.TickTask;
 
 /*
  * M#"""""""'M  dP                   dP       M""M            dP                                         dP   
@@ -79,6 +83,15 @@ public class BlockInteractData extends ACheckData {
     public double speedVL		= 0;
     public double visibleVL		= 0;
     
+    // General data
+    // Last block interacted with
+    public int lastX = Integer.MAX_VALUE;
+    public int lastY, lastZ;
+    /** null for air */
+    public Material lastType = null;
+    public long lastTick;
+    public Action lastAction = null;
+
     // Data of the reach check.
     public double reachDistance;
     
@@ -87,4 +100,27 @@ public class BlockInteractData extends ACheckData {
     /** Number of interactions since last reset-time. */
     public int  speedCount	= 0;
     
+    /**
+     * Last interacted block.
+     * @param block
+     */
+	public void setLastBlock(Block block, Action action) {
+		lastX = block.getX();
+		lastY = block.getY();
+		lastZ = block.getZ();
+		lastType = block.getType();
+		if (lastType == Material.AIR) {
+			lastType = null;
+		}
+		lastTick = TickTask.getTick();
+		lastAction = action;
+	}
+
+	public void resetLastBlock() {
+		lastTick = 0;
+		lastAction = null;
+		lastX = Integer.MAX_VALUE;
+		lastType = null;
+	}
+    
 }

NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/blockinteract/BlockInteractListener.java

@@ -83,7 +83,8 @@ public class BlockInteractListener extends CheckListener {
         	return;
         }
     	final Player player = event.getPlayer();
-        
+    	final BlockInteractData data = BlockInteractData.getData(player);
+    	data.setLastBlock(block, action);
         switch(action){
         case LEFT_CLICK_BLOCK:
         	break;
@@ -106,9 +107,7 @@ public class BlockInteractListener extends CheckListener {
         	return;
         }
         
-        final BlockInteractData data = BlockInteractData.getData(player);
         final BlockInteractConfig cc = BlockInteractConfig.getConfig(player);
-
         boolean cancelled = false;
         
         final BlockFace face = event.getBlockFace();

NCPCore/src/main/java/fr/neatmonster/nocheatplus/checks/blockplace/Against.java

@@ -9,7 +9,11 @@ import fr.neatmonster.nocheatplus.actions.ParameterName;
 import fr.neatmonster.nocheatplus.checks.Check;
 import fr.neatmonster.nocheatplus.checks.CheckType;
 import fr.neatmonster.nocheatplus.checks.ViolationData;
+import fr.neatmonster.nocheatplus.checks.blockbreak.BlockBreakData;
+import fr.neatmonster.nocheatplus.checks.blockinteract.BlockInteractData;
 import fr.neatmonster.nocheatplus.utilities.BlockProperties;
+import fr.neatmonster.nocheatplus.utilities.TickTask;
+import fr.neatmonster.nocheatplus.utilities.TrigUtil;
 /**
  * Check if the placing is legitimate in terms of surrounding materials.
  * @author mc_dev
@@ -21,12 +25,24 @@ public class Against extends Check {
 		super(CheckType.BLOCKPLACE_AGAINST);
 	}
 	
-	public boolean check(final Player player, final Block block, final Material mat, final Block blockAgainst, final BlockPlaceData data, final BlockPlaceConfig cc) {
+	public boolean check(final Player player, final Block block, final Material placedMat, final Block blockAgainst, final BlockPlaceData data, final BlockPlaceConfig cc) {
 		boolean violation = false;
 		// TODO: Make more precise (workarounds like WATER_LILY, general points).
+		// Workaround for signs on cactus and similar.
         final int againstId = blockAgainst.getTypeId();
+        if (againstId == Material.AIR.getId()) {
+        	// Attempt to workaround blocks like cactus.
+        	final BlockInteractData bdata = BlockInteractData.getData(player);
+        	if (bdata.lastType != null && bdata.lastX != Integer.MAX_VALUE && TickTask.getTick() == bdata.lastTick && TrigUtil.manhattan(bdata.lastX, bdata.lastY, bdata.lastZ, blockAgainst) == 0) {
+        		// (Wide screen.)
+        		// Block was placed against something (e.g. cactus), allow it.
+        		// TODO: Later reset can conflict, though it makes sense to reset with placing blocks in general.
+        		bdata.resetLastBlock(); 
+        		return false;
+        	}
+        }
         if (BlockProperties.isLiquid(againstId)) {
-            if ((mat != Material.WATER_LILY || !BlockProperties.isLiquid(block.getRelative(BlockFace.DOWN).getTypeId()))) {
+            if ((placedMat != Material.WATER_LILY || !BlockProperties.isLiquid(block.getRelative(BlockFace.DOWN).getTypeId()))) {
             	violation = true;
             }
         }
@@ -37,7 +53,7 @@ public class Against extends Check {
 		if (violation) {
 			data.againstVL += 1.0;
 			final ViolationData vd = new ViolationData(this, player, data.againstVL, 1, cc.againstActions);
-			vd.setParameter(ParameterName.BLOCK_ID, Integer.toString(mat.getId()));
+			vd.setParameter(ParameterName.BLOCK_ID, Integer.toString(placedMat.getId()));
 			return executeActions(vd);
 		} else {
 			data.againstVL *=  100; // Assume one false positive every 100 blocks.