Paper/Spigot-Server-Patches/0340-Anti-Xray.patch

From eda7118f1c06e049a257a9423a21c1ef620a4f4f Mon Sep 17 00:00:00 2001
From: stonar96 <minecraft.stonar96@gmail.com>
Date: Mon, 20 Aug 2018 03:03:58 +0200
Subject: [PATCH] Anti-Xray


diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index ac07bcc751..ca93fab889 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -1,7 +1,10 @@
 package com.destroystokyo.paper;
 
+import java.util.Arrays;
 import java.util.List;
 
+import com.destroystokyo.paper.antixray.ChunkPacketBlockControllerAntiXray.ChunkEdgeMode;
+import com.destroystokyo.paper.antixray.ChunkPacketBlockControllerAntiXray.EngineMode;
 import net.minecraft.server.MinecraftServer;
 import org.bukkit.Bukkit;
 import org.bukkit.configuration.file.YamlConfiguration;
@@ -508,4 +511,27 @@ public class PaperWorldConfig {
         this.armorStandTick = this.getBoolean("armor-stands-tick", this.armorStandTick);
         log("ArmorStand ticking is " + (this.armorStandTick ? "enabled" : "disabled") + " by default");
     }
+
+    public boolean antiXray;
+    public boolean asynchronous;
+    public EngineMode engineMode;
+    public ChunkEdgeMode chunkEdgeMode;
+    public int maxChunkSectionIndex;
+    public int updateRadius;
+    public List<String> hiddenBlocks;
+    public List<String> replacementBlocks;
+    private void antiXray() {
+        antiXray = getBoolean("anti-xray.enabled", false);
+        asynchronous = true;
+        engineMode = EngineMode.getById(getInt("anti-xray.engine-mode", EngineMode.HIDE.getId()));
+        engineMode = engineMode == null ? EngineMode.HIDE : engineMode;
+        chunkEdgeMode = ChunkEdgeMode.getById(getInt("anti-xray.chunk-edge-mode", ChunkEdgeMode.DEFAULT.getId()));
+        chunkEdgeMode = chunkEdgeMode == null ? ChunkEdgeMode.DEFAULT : chunkEdgeMode;
+        maxChunkSectionIndex = getInt("anti-xray.max-chunk-section-index", 3);
+        maxChunkSectionIndex = maxChunkSectionIndex > 15 ? 15 : maxChunkSectionIndex;
+        updateRadius = getInt("anti-xray.update-radius", 2);
+        hiddenBlocks = getList("anti-xray.hidden-blocks", Arrays.asList("gold_ore", "iron_ore", "coal_ore", "lapis_ore", "mossy_cobblestone", "obsidian", "chest", "diamond_ore", "redstone_ore", "lit_redstone_ore", "clay", "emerald_ore", "ender_chest"));
+        replacementBlocks = getList("anti-xray.replacement-blocks", Arrays.asList("stone", "planks"));
+        log("Anti-Xray: " + (antiXray ? "enabled" : "disabled") + " / Engine Mode: " + engineMode.getDescription() + " / Chunk Edge Mode: " + chunkEdgeMode.getDescription() + " / Up to " + ((maxChunkSectionIndex + 1) * 16) + " blocks / Update Radius: " + updateRadius);
+    }
 }
diff --git a/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockController.java b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockController.java
new file mode 100644
index 0000000000..1ba8477bf9
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockController.java
@@ -0,0 +1,45 @@
+package com.destroystokyo.paper.antixray;
+
+import net.minecraft.server.BlockPosition;
+import net.minecraft.server.Chunk;
+import net.minecraft.server.ChunkSection;
+import net.minecraft.server.EnumDirection;
+import net.minecraft.server.IBlockData;
+import net.minecraft.server.IChunkAccess;
+import net.minecraft.server.IWorldReader;
+import net.minecraft.server.PacketPlayOutMapChunk;
+import net.minecraft.server.PlayerInteractManager;
+import net.minecraft.server.World;
+
+public class ChunkPacketBlockController {
+
+    public static final ChunkPacketBlockController NO_OPERATION_INSTANCE = new ChunkPacketBlockController();
+
+    protected ChunkPacketBlockController() {
+
+    }
+
+    public IBlockData[] getPredefinedBlockData(IWorldReader world, IChunkAccess chunk, ChunkSection chunkSection, boolean skyLight, boolean initializeBlocks) {
+        return null;
+    }
+
+    public boolean onChunkPacketCreate(Chunk chunk, int chunkSectionSelector, boolean force) {
+        return true;
+    }
+
+    public ChunkPacketInfo<IBlockData> getChunkPacketInfo(PacketPlayOutMapChunk packetPlayOutMapChunk, Chunk chunk, int chunkSectionSelector) {
+        return null;
+    }
+
+    public void modifyBlocks(PacketPlayOutMapChunk packetPlayOutMapChunk, ChunkPacketInfo<IBlockData> chunkPacketInfo) {
+        packetPlayOutMapChunk.setReady(true);
+    }
+
+    public void onBlockChange(World world, BlockPosition blockPosition, IBlockData newBlockData, IBlockData oldBlockData, int flag) {
+
+    }
+
+    public void onPlayerLeftClickBlock(PlayerInteractManager playerInteractManager, BlockPosition blockPosition, EnumDirection enumDirection) {
+
+    }
+}
diff --git a/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java
new file mode 100644
index 0000000000..d00e113ba8
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java
@@ -0,0 +1,670 @@
+package com.destroystokyo.paper.antixray;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import net.minecraft.server.IRegistry;
+import net.minecraft.server.MinecraftKey;
+import org.bukkit.World.Environment;
+
+import com.destroystokyo.paper.PaperWorldConfig;
+
+import net.minecraft.server.Block;
+import net.minecraft.server.BlockPosition;
+import net.minecraft.server.Blocks;
+import net.minecraft.server.Chunk;
+import net.minecraft.server.ChunkSection;
+import net.minecraft.server.DataPalette;
+import net.minecraft.server.EnumDirection;
+import net.minecraft.server.GeneratorAccess;
+import net.minecraft.server.IBlockData;
+import net.minecraft.server.IChunkAccess;
+import net.minecraft.server.IWorldReader;
+import net.minecraft.server.PacketPlayOutMapChunk;
+import net.minecraft.server.PlayerInteractManager;
+import net.minecraft.server.World;
+
+public class ChunkPacketBlockControllerAntiXray extends ChunkPacketBlockController {
+
+    private static ExecutorService executorServiceInstance = null;
+    private final ExecutorService executorService;
+    private final boolean asynchronous;
+    private final EngineMode engineMode;
+    private final ChunkEdgeMode chunkEdgeMode;
+    private final int maxChunkSectionIndex;
+    private final int updateRadius;
+    private final IBlockData[] predefinedBlockData;
+    private final IBlockData[] predefinedBlockDataStone;
+    private final IBlockData[] predefinedBlockDataNetherrack;
+    private final IBlockData[] predefinedBlockDataEndStone;
+    private final int[] predefinedBlockDataBitsGlobal;
+    private final int[] predefinedBlockDataBitsStoneGlobal;
+    private final int[] predefinedBlockDataBitsNetherrackGlobal;
+    private final int[] predefinedBlockDataBitsEndStoneGlobal;
+    private final boolean[] solidGlobal = new boolean[Block.REGISTRY_ID.size()];
+    private final boolean[] obfuscateGlobal = new boolean[Block.REGISTRY_ID.size()];
+    private final ChunkSection[] emptyNearbyChunkSections = {Chunk.EMPTY_CHUNK_SECTION, Chunk.EMPTY_CHUNK_SECTION, Chunk.EMPTY_CHUNK_SECTION, Chunk.EMPTY_CHUNK_SECTION};
+    private final int maxBlockYUpdatePosition;
+
+    public ChunkPacketBlockControllerAntiXray(PaperWorldConfig paperWorldConfig) {
+        asynchronous = paperWorldConfig.asynchronous;
+        engineMode = paperWorldConfig.engineMode;
+        chunkEdgeMode = paperWorldConfig.chunkEdgeMode;
+        maxChunkSectionIndex = paperWorldConfig.maxChunkSectionIndex;
+        updateRadius = paperWorldConfig.updateRadius;
+
+        if (asynchronous) {
+            executorService = getExecutorServiceInstance();
+        } else {
+            executorService = null;
+        }
+
+        if (engineMode == EngineMode.HIDE) {
+            predefinedBlockData = null;
+            predefinedBlockDataStone = new IBlockData[] {Blocks.STONE.getBlockData()};
+            predefinedBlockDataNetherrack = new IBlockData[] {Blocks.NETHERRACK.getBlockData()};
+            predefinedBlockDataEndStone = new IBlockData[] {Blocks.END_STONE.getBlockData()};
+            predefinedBlockDataBitsGlobal = null;
+            predefinedBlockDataBitsStoneGlobal = new int[] {ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(Blocks.STONE.getBlockData())};
+            predefinedBlockDataBitsNetherrackGlobal = new int[] {ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(Blocks.NETHERRACK.getBlockData())};
+            predefinedBlockDataBitsEndStoneGlobal = new int[] {ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(Blocks.END_STONE.getBlockData())};
+        } else {
+            Set<IBlockData> predefinedBlockDataSet = new HashSet<IBlockData>();
+
+            for (String id : paperWorldConfig.hiddenBlocks) {
+                Block block = IRegistry.BLOCK.get(new MinecraftKey(id));
+
+                if (block != null && !block.isTileEntity()) {
+                    predefinedBlockDataSet.add(block.getBlockData());
+                }
+            }
+
+            predefinedBlockData = predefinedBlockDataSet.size() == 0 ? new IBlockData[] {Blocks.DIAMOND_ORE.getBlockData()} : predefinedBlockDataSet.toArray(new IBlockData[predefinedBlockDataSet.size()]);
+            predefinedBlockDataStone = null;
+            predefinedBlockDataNetherrack = null;
+            predefinedBlockDataEndStone = null;
+            predefinedBlockDataBitsGlobal = new int[predefinedBlockData.length];
+
+            for (int i = 0; i < predefinedBlockData.length; i++) {
+                predefinedBlockDataBitsGlobal[i] = ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(predefinedBlockData[i]);
+            }
+
+            predefinedBlockDataBitsStoneGlobal = null;
+            predefinedBlockDataBitsNetherrackGlobal = null;
+            predefinedBlockDataBitsEndStoneGlobal = null;
+        }
+
+        for (String id : (engineMode == EngineMode.HIDE) ? paperWorldConfig.hiddenBlocks : paperWorldConfig.replacementBlocks) {
+            Block block = IRegistry.BLOCK.get(new MinecraftKey(id));
+
+            if (block != null) {
+                obfuscateGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(block.getBlockData())] = true;
+            }
+        }
+
+        for (int i = 0; i < solidGlobal.length; i++) {
+            IBlockData blockData = ChunkSection.GLOBAL_PALETTE.getObject(i);
+
+            if (blockData != null) {
+                solidGlobal[i] = blockData.getBlock().isOccluding(blockData) && blockData.getBlock() != Blocks.SPAWNER && blockData.getBlock() != Blocks.BARRIER;
+            }
+        }
+
+        this.maxBlockYUpdatePosition = (maxChunkSectionIndex + 1) * 16 + updateRadius - 1;
+    }
+
+    private static ExecutorService getExecutorServiceInstance() {
+        if (executorServiceInstance == null) {
+            executorServiceInstance = Executors.newSingleThreadExecutor();
+        }
+
+        return executorServiceInstance;
+    }
+
+    @Override
+    public IBlockData[] getPredefinedBlockData(IWorldReader world, IChunkAccess chunk, ChunkSection chunkSection, boolean skyLight, boolean initializeBlocks) {
+        //Return the block data which should be added to the data palettes so that they can be used for the obfuscation
+        if (chunkSection.getYPosition() >> 4 <= maxChunkSectionIndex) {
+            switch (engineMode) {
+                case HIDE:
+                    if (world instanceof GeneratorAccess) {
+                        switch (((GeneratorAccess) world).getMinecraftWorld().getWorld().getEnvironment()) {
+                            case NETHER:
+                                return predefinedBlockDataNetherrack;
+                            case THE_END:
+                                return predefinedBlockDataEndStone;
+                            default:
+                                return predefinedBlockDataStone;
+                        }
+                    }
+
+                    return null;
+                default:
+                    return predefinedBlockData;
+            }
+        }
+
+        return null;
+    }
+
+    @Override
+    public boolean onChunkPacketCreate(Chunk chunk, int chunkSectionSelector, boolean force) {
+        //Load nearby chunks if necessary
+        if (chunkEdgeMode == ChunkEdgeMode.WAIT && !force) {
+            if (chunk.world.getChunkIfLoaded(chunk.locX - 1, chunk.locZ) == null || chunk.world.getChunkIfLoaded(chunk.locX + 1, chunk.locZ) == null || chunk.world.getChunkIfLoaded(chunk.locX, chunk.locZ - 1) == null || chunk.world.getChunkIfLoaded(chunk.locX, chunk.locZ + 1) == null) {
+                //Don't create the chunk packet now, wait until nearby chunks are loaded and create it later
+                return false;
+            }
+        } else if (chunkEdgeMode == ChunkEdgeMode.LOAD || chunkEdgeMode == ChunkEdgeMode.WAIT) {
+            chunk.world.getChunkAt(chunk.locX - 1, chunk.locZ);
+            chunk.world.getChunkAt(chunk.locX + 1, chunk.locZ);
+            chunk.world.getChunkAt(chunk.locX, chunk.locZ - 1);
+            chunk.world.getChunkAt(chunk.locX, chunk.locZ + 1);
+        }
+
+        //Create the chunk packet now
+        return true;
+    }
+
+    @Override
+    public ChunkPacketInfoAntiXray getChunkPacketInfo(PacketPlayOutMapChunk packetPlayOutMapChunk, Chunk chunk, int chunkSectionSelector) {
+        //Return a new instance to collect data and objects in the right state while creating the chunk packet for thread safe access later
+        ChunkPacketInfoAntiXray chunkPacketInfoAntiXray = new ChunkPacketInfoAntiXray(packetPlayOutMapChunk, chunk, chunkSectionSelector, this);
+        chunkPacketInfoAntiXray.setNearbyChunks(chunk.world.getChunkIfLoaded(chunk.locX - 1, chunk.locZ), chunk.world.getChunkIfLoaded(chunk.locX + 1, chunk.locZ), chunk.world.getChunkIfLoaded(chunk.locX, chunk.locZ - 1), chunk.world.getChunkIfLoaded(chunk.locX, chunk.locZ + 1));
+        return chunkPacketInfoAntiXray;
+    }
+
+    @Override
+    public void modifyBlocks(PacketPlayOutMapChunk packetPlayOutMapChunk, ChunkPacketInfo<IBlockData> chunkPacketInfo) {
+        if (asynchronous) {
+            executorService.submit((ChunkPacketInfoAntiXray) chunkPacketInfo);
+        } else {
+            obfuscate((ChunkPacketInfoAntiXray) chunkPacketInfo);
+        }
+    }
+
+    //Actually these fields should be variables inside the obfuscate method but in sync mode or with SingleThreadExecutor in async mode it's okay
+    private int[] predefinedBlockDataBits;
+    private final boolean[] solid = new boolean[Block.REGISTRY_ID.size()];
+    private final boolean[] obfuscate = new boolean[Block.REGISTRY_ID.size()];
+    //These boolean arrays represent chunk layers, true means don't obfuscate, false means obfuscate
+    private boolean[][] current = new boolean[16][16];
+    private boolean[][] next = new boolean[16][16];
+    private boolean[][] nextNext = new boolean[16][16];
+    private final DataBitsReader dataBitsReader = new DataBitsReader();
+    private final DataBitsWriter dataBitsWriter = new DataBitsWriter();
+    private final ChunkSection[] nearbyChunkSections = new ChunkSection[4];
+
+    public void obfuscate(ChunkPacketInfoAntiXray chunkPacketInfoAntiXray) {
+        boolean[] solidTemp = null;
+        boolean[] obfuscateTemp = null;
+        dataBitsReader.setDataBits(chunkPacketInfoAntiXray.getData());
+        dataBitsWriter.setDataBits(chunkPacketInfoAntiXray.getData());
+        int counter = 0;
+
+        for (int chunkSectionIndex = 0; chunkSectionIndex <= maxChunkSectionIndex; chunkSectionIndex++) {
+            if (chunkPacketInfoAntiXray.isWritten(chunkSectionIndex) && chunkPacketInfoAntiXray.getPredefinedObjects(chunkSectionIndex) != null) {
+                int[] predefinedBlockDataBitsTemp;
+
+                if (chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex) == ChunkSection.GLOBAL_PALETTE) {
+                    predefinedBlockDataBitsTemp = engineMode == EngineMode.HIDE ? chunkPacketInfoAntiXray.getChunk().world.getWorld().getEnvironment() == Environment.NETHER ? predefinedBlockDataBitsNetherrackGlobal : chunkPacketInfoAntiXray.getChunk().world.getWorld().getEnvironment() == Environment.THE_END ? predefinedBlockDataBitsEndStoneGlobal : predefinedBlockDataBitsStoneGlobal : predefinedBlockDataBitsGlobal;
+                } else {
+                    predefinedBlockDataBitsTemp = predefinedBlockDataBits == null ? predefinedBlockDataBits = engineMode == EngineMode.HIDE ? new int[1] : new int[predefinedBlockData.length] : predefinedBlockDataBits;
+
+                    for (int i = 0; i < predefinedBlockDataBitsTemp.length; i++) {
+                        predefinedBlockDataBitsTemp[i] = chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex).getOrCreateIdFor(chunkPacketInfoAntiXray.getPredefinedObjects(chunkSectionIndex)[i]);
+                    }
+                }
+
+                dataBitsWriter.setIndex(chunkPacketInfoAntiXray.getOrCreateIdForIndex(chunkSectionIndex));
+
+                //Check if the chunk section below was not obfuscated
+                if (chunkSectionIndex == 0 || !chunkPacketInfoAntiXray.isWritten(chunkSectionIndex - 1) || chunkPacketInfoAntiXray.getPredefinedObjects(chunkSectionIndex - 1) == null) {
+                    //If so, initialize some stuff
+                    dataBitsReader.setBitsPerObject(chunkPacketInfoAntiXray.getBitsPerObject(chunkSectionIndex));
+                    dataBitsReader.setIndex(chunkPacketInfoAntiXray.getOrCreateIdForIndex(chunkSectionIndex));
+                    solidTemp = readDataPalette(chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex), solid, solidGlobal);
+                    obfuscateTemp = readDataPalette(chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex), obfuscate, obfuscateGlobal);
+                    //Read the blocks of the upper layer of the chunk section below if it exists
+                    ChunkSection belowChunkSection = null;
+                    boolean skipFirstLayer = chunkSectionIndex == 0 || (belowChunkSection = chunkPacketInfoAntiXray.getChunk().getSections()[chunkSectionIndex - 1]) == Chunk.EMPTY_CHUNK_SECTION;
+
+                    for (int z = 0; z < 16; z++) {
+                        for (int x = 0; x < 16; x++) {
+                            current[z][x] = true;
+                            next[z][x] = skipFirstLayer || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(belowChunkSection.getType(x, 15, z))];
+                        }
+                    }
+
+                    //Abuse the obfuscateLayer method to read the blocks of the first layer of the current chunk section
+                    dataBitsWriter.setBitsPerObject(0);
+                    obfuscateLayer(-1, dataBitsReader, dataBitsWriter, solidTemp, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, emptyNearbyChunkSections, counter);
+                }
+
+                dataBitsWriter.setBitsPerObject(chunkPacketInfoAntiXray.getBitsPerObject(chunkSectionIndex));
+                nearbyChunkSections[0] = chunkPacketInfoAntiXray.getNearbyChunks()[0] == null ? Chunk.EMPTY_CHUNK_SECTION : chunkPacketInfoAntiXray.getNearbyChunks()[0].getSections()[chunkSectionIndex];
+                nearbyChunkSections[1] = chunkPacketInfoAntiXray.getNearbyChunks()[1] == null ? Chunk.EMPTY_CHUNK_SECTION : chunkPacketInfoAntiXray.getNearbyChunks()[1].getSections()[chunkSectionIndex];
+                nearbyChunkSections[2] = chunkPacketInfoAntiXray.getNearbyChunks()[2] == null ? Chunk.EMPTY_CHUNK_SECTION : chunkPacketInfoAntiXray.getNearbyChunks()[2].getSections()[chunkSectionIndex];
+                nearbyChunkSections[3] = chunkPacketInfoAntiXray.getNearbyChunks()[3] == null ? Chunk.EMPTY_CHUNK_SECTION : chunkPacketInfoAntiXray.getNearbyChunks()[3].getSections()[chunkSectionIndex];
+
+                //Obfuscate all layers of the current chunk section except the upper one
+                for (int y = 0; y < 15; y++) {
+                    boolean[][] temp = current;
+                    current = next;
+                    next = nextNext;
+                    nextNext = temp;
+                    counter = obfuscateLayer(y, dataBitsReader, dataBitsWriter, solidTemp, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, nearbyChunkSections, counter);
+                }
+
+                //Check if the chunk section above doesn't need obfuscation
+                if (chunkSectionIndex == maxChunkSectionIndex || !chunkPacketInfoAntiXray.isWritten(chunkSectionIndex + 1) || chunkPacketInfoAntiXray.getPredefinedObjects(chunkSectionIndex + 1) == null) {
+                    //If so, obfuscate the upper layer of the current chunk section by reading blocks of the first layer from the chunk section above if it exists
+                    ChunkSection aboveChunkSection;
+
+                    if (chunkSectionIndex != 15 && (aboveChunkSection = chunkPacketInfoAntiXray.getChunk().getSections()[chunkSectionIndex + 1]) != Chunk.EMPTY_CHUNK_SECTION) {
+                        boolean[][] temp = current;
+                        current = next;
+                        next = nextNext;
+                        nextNext = temp;
+
+                        for (int z = 0; z < 16; z++) {
+                            for (int x = 0; x < 16; x++) {
+                                if (!solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(aboveChunkSection.getType(x, 0, z))]) {
+                                    current[z][x] = true;
+                                }
+                            }
+                        }
+
+                        //There is nothing to read anymore
+                        dataBitsReader.setBitsPerObject(0);
+                        solid[0] = true;
+                        counter = obfuscateLayer(15, dataBitsReader, dataBitsWriter, solid, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, nearbyChunkSections, counter);
+                    }
+                } else {
+                    //If not, initialize the reader and other stuff for the chunk section above to obfuscate the upper layer of the current chunk section
+                    dataBitsReader.setBitsPerObject(chunkPacketInfoAntiXray.getBitsPerObject(chunkSectionIndex + 1));
+                    dataBitsReader.setIndex(chunkPacketInfoAntiXray.getOrCreateIdForIndex(chunkSectionIndex + 1));
+                    solidTemp = readDataPalette(chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex + 1), solid, solidGlobal);
+                    obfuscateTemp = readDataPalette(chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex + 1), obfuscate, obfuscateGlobal);
+                    boolean[][] temp = current;
+                    current = next;
+                    next = nextNext;
+                    nextNext = temp;
+                    counter = obfuscateLayer(15, dataBitsReader, dataBitsWriter, solidTemp, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, nearbyChunkSections, counter);
+                }
+
+                dataBitsWriter.finish();
+            }
+        }
+
+        chunkPacketInfoAntiXray.getPacketPlayOutMapChunk().setReady(true);
+    }
+
+    private int obfuscateLayer(int y, DataBitsReader dataBitsReader, DataBitsWriter dataBitsWriter, boolean[] solid, boolean[] obfuscate, int[] predefinedBlockDataBits, boolean[][] current, boolean[][] next, boolean[][] nextNext, ChunkSection[] nearbyChunkSections, int counter) {
+        //First block of first line
+        int dataBits = dataBitsReader.read();
+
+        if (nextNext[0][0] = !solid[dataBits]) {
+            dataBitsWriter.skip();
+            next[0][1] = true;
+            next[1][0] = true;
+        } else {
+            if (nearbyChunkSections[2] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[2].getType(0, y, 15))] || nearbyChunkSections[0] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[0].getType(15, y, 0))] || current[0][0]) {
+                dataBitsWriter.skip();
+            } else {
+                if (counter >= predefinedBlockDataBits.length) {
+                    counter = 0;
+                }
+
+                dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+            }
+        }
+
+        if (!obfuscate[dataBits]) {
+            next[0][0] = true;
+        }
+
+        //First line
+        for (int x = 1; x < 15; x++) {
+            dataBits = dataBitsReader.read();
+
+            if (nextNext[0][x] = !solid[dataBits]) {
+                dataBitsWriter.skip();
+                next[0][x - 1] = true;
+                next[0][x + 1] = true;
+                next[1][x] = true;
+            } else {
+                if (nearbyChunkSections[2] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[2].getType(x, y, 15))] || current[0][x]) {
+                    dataBitsWriter.skip();
+                } else {
+                    if (counter >= predefinedBlockDataBits.length) {
+                        counter = 0;
+                    }
+
+                    dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+                }
+            }
+
+            if (!obfuscate[dataBits]) {
+                next[0][x] = true;
+            }
+        }
+
+        //Last block of first line
+        dataBits = dataBitsReader.read();
+
+        if (nextNext[0][15] = !solid[dataBits]) {
+            dataBitsWriter.skip();
+            next[0][14] = true;
+            next[1][15] = true;
+        } else {
+            if (nearbyChunkSections[2] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[2].getType(15, y, 15))] || nearbyChunkSections[1] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[1].getType(0, y, 0))] || current[0][15]) {
+                dataBitsWriter.skip();
+            } else {
+                if (counter >= predefinedBlockDataBits.length) {
+                    counter = 0;
+                }
+
+                dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+            }
+        }
+
+        if (!obfuscate[dataBits]) {
+            next[0][15] = true;
+        }
+
+        //All inner lines
+        for (int z = 1; z < 15; z++) {
+            //First block
+            dataBits = dataBitsReader.read();
+
+            if (nextNext[z][0] = !solid[dataBits]) {
+                dataBitsWriter.skip();
+                next[z][1] = true;
+                next[z - 1][0] = true;
+                next[z + 1][0] = true;
+            } else {
+                if (nearbyChunkSections[0] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[0].getType(15, y, z))] || current[z][0]) {
+                    dataBitsWriter.skip();
+                } else {
+                    if (counter >= predefinedBlockDataBits.length) {
+                        counter = 0;
+                    }
+
+                    dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+                }
+            }
+
+            if (!obfuscate[dataBits]) {
+                next[z][0] = true;
+            }
+
+            //All inner blocks
+            for (int x = 1; x < 15; x++) {
+                dataBits = dataBitsReader.read();
+
+                if (nextNext[z][x] = !solid[dataBits]) {
+                    dataBitsWriter.skip();
+                    next[z][x - 1] = true;
+                    next[z][x + 1] = true;
+                    next[z - 1][x] = true;
+                    next[z + 1][x] = true;
+                } else {
+                    if (current[z][x]) {
+                        dataBitsWriter.skip();
+                    } else {
+                        if (counter >= predefinedBlockDataBits.length) {
+                            counter = 0;
+                        }
+
+                        dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+                    }
+                }
+
+                if (!obfuscate[dataBits]) {
+                    next[z][x] = true;
+                }
+            }
+
+            //Last block
+            dataBits = dataBitsReader.read();
+
+            if (nextNext[z][15] = !solid[dataBits]) {
+                dataBitsWriter.skip();
+                next[z][14] = true;
+                next[z - 1][15] = true;
+                next[z + 1][15] = true;
+            } else {
+                if (nearbyChunkSections[1] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[1].getType(0, y, z))] || current[z][15]) {
+                    dataBitsWriter.skip();
+                } else {
+                    if (counter >= predefinedBlockDataBits.length) {
+                        counter = 0;
+                    }
+
+                    dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+                }
+            }
+
+            if (!obfuscate[dataBits]) {
+                next[z][15] = true;
+            }
+        }
+
+        //First block of last line
+        dataBits = dataBitsReader.read();
+
+        if (nextNext[15][0] = !solid[dataBits]) {
+            dataBitsWriter.skip();
+            next[15][1] = true;
+            next[14][0] = true;
+        } else {
+            if (nearbyChunkSections[3] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[3].getType(0, y, 0))] || nearbyChunkSections[0] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[0].getType(15, y, 15))] || current[15][0]) {
+                dataBitsWriter.skip();
+            } else {
+                if (counter >= predefinedBlockDataBits.length) {
+                    counter = 0;
+                }
+
+                dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+            }
+        }
+
+        if (!obfuscate[dataBits]) {
+            next[15][0] = true;
+        }
+
+        //Last line
+        for (int x = 1; x < 15; x++) {
+            dataBits = dataBitsReader.read();
+
+            if (nextNext[15][x] = !solid[dataBits]) {
+                dataBitsWriter.skip();
+                next[15][x - 1] = true;
+                next[15][x + 1] = true;
+                next[14][x] = true;
+            } else {
+                if (nearbyChunkSections[3] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[3].getType(x, y, 0))] || current[15][x]) {
+                    dataBitsWriter.skip();
+                } else {
+                    if (counter >= predefinedBlockDataBits.length) {
+                        counter = 0;
+                    }
+
+                    dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+                }
+            }
+
+            if (!obfuscate[dataBits]) {
+                next[15][x] = true;
+            }
+        }
+
+        //Last block of last line
+        dataBits = dataBitsReader.read();
+
+        if (nextNext[15][15] = !solid[dataBits]) {
+            dataBitsWriter.skip();
+            next[15][14] = true;
+            next[14][15] = true;
+        } else {
+            if (nearbyChunkSections[3] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[3].getType(15, y, 0))] || nearbyChunkSections[1] == Chunk.EMPTY_CHUNK_SECTION || !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(nearbyChunkSections[1].getType(0, y, 15))] || current[15][15]) {
+                dataBitsWriter.skip();
+            } else {
+                if (counter >= predefinedBlockDataBits.length) {
+                    counter = 0;
+                }
+
+                dataBitsWriter.write(predefinedBlockDataBits[counter++]);
+            }
+        }
+
+        if (!obfuscate[dataBits]) {
+            next[15][15] = true;
+        }
+
+        return counter;
+    }
+
+    private boolean[] readDataPalette(DataPalette<IBlockData> dataPalette, boolean[] temp, boolean[] global) {
+        if (dataPalette == ChunkSection.GLOBAL_PALETTE) {
+            return global;
+        }
+
+        IBlockData blockData;
+
+        for (int i = 0; (blockData = dataPalette.getObject(i)) != null; i++) {
+            temp[i] = global[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(blockData)];
+        }
+
+        return temp;
+    }
+
+    @Override
+    public void onBlockChange(World world, BlockPosition blockPosition, IBlockData newBlockData, IBlockData oldBlockData, int flag) {
+        if (oldBlockData != null && solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(oldBlockData)] && !solidGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(newBlockData)] && blockPosition.getY() <= maxBlockYUpdatePosition) {
+            updateNearbyBlocks(world, blockPosition);
+        }
+    }
+
+    @Override
+    public void onPlayerLeftClickBlock(PlayerInteractManager playerInteractManager, BlockPosition blockPosition, EnumDirection enumDirection) {
+        if (blockPosition.getY() <= maxBlockYUpdatePosition) {
+            updateNearbyBlocks(playerInteractManager.world, blockPosition);
+        }
+    }
+
+    private void updateNearbyBlocks(World world, BlockPosition blockPosition) {
+        if (updateRadius >= 2) {
+            BlockPosition temp = blockPosition.west();
+            updateBlock(world, temp);
+            updateBlock(world, temp.west());
+            updateBlock(world, temp.down());
+            updateBlock(world, temp.up());
+            updateBlock(world, temp.north());
+            updateBlock(world, temp.south());
+            updateBlock(world, temp = blockPosition.east());
+            updateBlock(world, temp.east());
+            updateBlock(world, temp.down());
+            updateBlock(world, temp.up());
+            updateBlock(world, temp.north());
+            updateBlock(world, temp.south());
+            updateBlock(world, temp = blockPosition.down());
+            updateBlock(world, temp.down());
+            updateBlock(world, temp.north());
+            updateBlock(world, temp.south());
+            updateBlock(world, temp = blockPosition.up());
+            updateBlock(world, temp.up());
+            updateBlock(world, temp.north());
+            updateBlock(world, temp.south());
+            updateBlock(world, temp = blockPosition.north());
+            updateBlock(world, temp.north());
+            updateBlock(world, temp = blockPosition.south());
+            updateBlock(world, temp.south());
+        } else if (updateRadius == 1) {
+            updateBlock(world, blockPosition.west());
+            updateBlock(world, blockPosition.east());
+            updateBlock(world, blockPosition.down());
+            updateBlock(world, blockPosition.up());
+            updateBlock(world, blockPosition.north());
+            updateBlock(world, blockPosition.south());
+        } else {
+            //Do nothing if updateRadius <= 0 (test mode)
+        }
+    }
+
+    private void updateBlock(World world, BlockPosition blockPosition) {
+        IBlockData blockData = world.getTypeIfLoaded(blockPosition);
+
+        if (blockData != null && obfuscateGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(blockData)]) {
+            world.notify(blockPosition, blockData, blockData, 3);
+        }
+    }
+
+    public enum EngineMode {
+
+        HIDE(1, "hide ores"),
+        OBFUSCATE(2, "obfuscate");
+
+        private final int id;
+        private final String description;
+
+        EngineMode(int id, String description) {
+            this.id = id;
+            this.description = description;
+        }
+
+        public static EngineMode getById(int id) {
+            for (EngineMode engineMode : values()) {
+                if (engineMode.id == id) {
+                    return engineMode;
+                }
+            }
+
+            return null;
+        }
+
+        public int getId() {
+            return id;
+        }
+
+        public String getDescription() {
+            return description;
+        }
+    }
+
+    public enum ChunkEdgeMode {
+
+        DEFAULT(1, "default"),
+        WAIT(2, "wait until nearby chunks are loaded"),
+        LOAD(3, "load nearby chunks");
+
+        private final int id;
+        private final String description;
+
+        ChunkEdgeMode(int id, String description) {
+            this.id = id;
+            this.description = description;
+        }
+
+        public static ChunkEdgeMode getById(int id) {
+            for (ChunkEdgeMode chunkEdgeMode : values()) {
+                if (chunkEdgeMode.id == id) {
+                    return chunkEdgeMode;
+                }
+            }
+
+            return null;
+        }
+
+        public int getId() {
+            return id;
+        }
+
+        public String getDescription() {
+            return description;
+        }
+    }
+}
diff --git a/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfo.java b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfo.java
new file mode 100644
index 0000000000..a68bace353
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfo.java
@@ -0,0 +1,81 @@
+package com.destroystokyo.paper.antixray;
+
+import net.minecraft.server.Chunk;
+import net.minecraft.server.DataPalette;
+import net.minecraft.server.PacketPlayOutMapChunk;
+
+public class ChunkPacketInfo<T> {
+
+    private final PacketPlayOutMapChunk packetPlayOutMapChunk;
+    private final Chunk chunk;
+    private final int chunkSectionSelector;
+    private byte[] data;
+    private final int[] bitsPerObject = new int[16];
+    private final Object[] dataPalettes = new Object[16];
+    private final int[] dataBitsIndexes = new int[16];
+    private final Object[][] predefinedObjects = new Object[16][];
+
+    public ChunkPacketInfo(PacketPlayOutMapChunk packetPlayOutMapChunk, Chunk chunk, int chunkSectionSelector) {
+        this.packetPlayOutMapChunk = packetPlayOutMapChunk;
+        this.chunk = chunk;
+        this.chunkSectionSelector = chunkSectionSelector;
+    }
+
+    public PacketPlayOutMapChunk getPacketPlayOutMapChunk() {
+        return packetPlayOutMapChunk;
+    }
+
+    public Chunk getChunk() {
+        return chunk;
+    }
+
+    public int getChunkSectionSelector() {
+        return chunkSectionSelector;
+    }
+
+    public byte[] getData() {
+        return data;
+    }
+
+    public void setData(byte[] data) {
+        this.data = data;
+    }
+
+    public int getBitsPerObject(int chunkSectionIndex) {
+        return bitsPerObject[chunkSectionIndex];
+    }
+
+    public void setBitsPerObject(int chunkSectionIndex, int bitsPerObject) {
+        this.bitsPerObject[chunkSectionIndex] = bitsPerObject;
+    }
+
+    @SuppressWarnings("unchecked")
+    public DataPalette<T> getDataPalette(int chunkSectionIndex) {
+        return (DataPalette<T>) dataPalettes[chunkSectionIndex];
+    }
+
+    public void setDataPalette(int chunkSectionIndex, DataPalette<T> dataPalette) {
+        dataPalettes[chunkSectionIndex] = dataPalette;
+    }
+
+    public int getOrCreateIdForIndex(int chunkSectionIndex) {
+        return dataBitsIndexes[chunkSectionIndex];
+    }
+
+    public void setDataBitsIndex(int chunkSectionIndex, int dataBitsIndex) {
+        dataBitsIndexes[chunkSectionIndex] = dataBitsIndex;
+    }
+
+    @SuppressWarnings("unchecked")
+    public T[] getPredefinedObjects(int chunkSectionIndex) {
+        return (T[]) predefinedObjects[chunkSectionIndex];
+    }
+
+    public void setPredefinedObjects(int chunkSectionIndex, T[] predefinedObjects) {
+        this.predefinedObjects[chunkSectionIndex] = predefinedObjects;
+    }
+
+    public boolean isWritten(int chunkSectionIndex) {
+        return bitsPerObject[chunkSectionIndex] != 0;
+    }
+}
diff --git a/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfoAntiXray.java b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfoAntiXray.java
new file mode 100644
index 0000000000..e255a45fa3
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfoAntiXray.java
@@ -0,0 +1,29 @@
+package com.destroystokyo.paper.antixray;
+
+import net.minecraft.server.Chunk;
+import net.minecraft.server.IBlockData;
+import net.minecraft.server.PacketPlayOutMapChunk;
+
+public class ChunkPacketInfoAntiXray extends ChunkPacketInfo<IBlockData> implements Runnable {
+
+    private Chunk[] nearbyChunks;
+    private final ChunkPacketBlockControllerAntiXray chunkPacketBlockControllerAntiXray;
+
+    public ChunkPacketInfoAntiXray(PacketPlayOutMapChunk packetPlayOutMapChunk, Chunk chunk, int chunkSectionSelector, ChunkPacketBlockControllerAntiXray chunkPacketBlockControllerAntiXray) {
+        super(packetPlayOutMapChunk, chunk, chunkSectionSelector);
+        this.chunkPacketBlockControllerAntiXray = chunkPacketBlockControllerAntiXray;
+    }
+
+    public Chunk[] getNearbyChunks() {
+        return nearbyChunks;
+    }
+
+    public void setNearbyChunks(Chunk... nearbyChunks) {
+        this.nearbyChunks = nearbyChunks;
+    }
+
+    @Override
+    public void run() {
+        chunkPacketBlockControllerAntiXray.obfuscate(this);
+    }
+}
diff --git a/src/main/java/com/destroystokyo/paper/antixray/DataBitsReader.java b/src/main/java/com/destroystokyo/paper/antixray/DataBitsReader.java
new file mode 100644
index 0000000000..cc586827aa
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/DataBitsReader.java
@@ -0,0 +1,56 @@
+package com.destroystokyo.paper.antixray;
+
+public class DataBitsReader {
+
+    private byte[] dataBits;
+    private int bitsPerObject;
+    private int mask;
+    private int longInDataBitsIndex;
+    private int bitInLongIndex;
+    private long current;
+
+    public void setDataBits(byte[] dataBits) {
+        this.dataBits = dataBits;
+    }
+
+    public void setBitsPerObject(int bitsPerObject) {
+        this.bitsPerObject = bitsPerObject;
+        mask = (1 << bitsPerObject) - 1;
+    }
+
+    public void setIndex(int index) {
+        this.longInDataBitsIndex = index;
+        bitInLongIndex = 0;
+        init();
+    }
+
+    private void init() {
+        if (dataBits.length > longInDataBitsIndex + 7) {
+            current = ((((long) dataBits[longInDataBitsIndex]) << 56)
+                    | (((long) dataBits[longInDataBitsIndex + 1] & 0xff) << 48)
+                    | (((long) dataBits[longInDataBitsIndex + 2] & 0xff) << 40)
+                    | (((long) dataBits[longInDataBitsIndex + 3] & 0xff) << 32)
+                    | (((long) dataBits[longInDataBitsIndex + 4] & 0xff) << 24)
+                    | (((long) dataBits[longInDataBitsIndex + 5] & 0xff) << 16)
+                    | (((long) dataBits[longInDataBitsIndex + 6] & 0xff) << 8)
+                    | (((long) dataBits[longInDataBitsIndex + 7] & 0xff)));
+        }
+    }
+
+    public int read() {
+        int value = (int) (current >>> bitInLongIndex) & mask;
+        bitInLongIndex += bitsPerObject;
+
+        if (bitInLongIndex > 63) {
+            bitInLongIndex -= 64;
+            longInDataBitsIndex += 8;
+            init();
+
+            if (bitInLongIndex > 0) {
+                value |= current << bitsPerObject - bitInLongIndex & mask;
+            }
+        }
+
+        return value;
+    }
+}
diff --git a/src/main/java/com/destroystokyo/paper/antixray/DataBitsWriter.java b/src/main/java/com/destroystokyo/paper/antixray/DataBitsWriter.java
new file mode 100644
index 0000000000..37093419cf
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/DataBitsWriter.java
@@ -0,0 +1,84 @@
+package com.destroystokyo.paper.antixray;
+
+public class DataBitsWriter {
+
+    private byte[] dataBits;
+    private int bitsPerObject;
+    private long mask;
+    private int longInDataBitsIndex;
+    private int bitInLongIndex;
+    private long current;
+    private boolean dirty;
+
+    public void setDataBits(byte[] dataBits) {
+        this.dataBits = dataBits;
+    }
+
+    public void setBitsPerObject(int bitsPerObject) {
+        this.bitsPerObject = bitsPerObject;
+        mask = (1 << bitsPerObject) - 1;
+    }
+
+    public void setIndex(int index) {
+        this.longInDataBitsIndex = index;
+        bitInLongIndex = 0;
+        init();
+    }
+
+    private void init() {
+        if (dataBits.length > longInDataBitsIndex + 7) {
+            current = ((((long) dataBits[longInDataBitsIndex]) << 56)
+                    | (((long) dataBits[longInDataBitsIndex + 1] & 0xff) << 48)
+                    | (((long) dataBits[longInDataBitsIndex + 2] & 0xff) << 40)
+                    | (((long) dataBits[longInDataBitsIndex + 3] & 0xff) << 32)
+                    | (((long) dataBits[longInDataBitsIndex + 4] & 0xff) << 24)
+                    | (((long) dataBits[longInDataBitsIndex + 5] & 0xff) << 16)
+                    | (((long) dataBits[longInDataBitsIndex + 6] & 0xff) << 8)
+                    | (((long) dataBits[longInDataBitsIndex + 7] & 0xff)));
+        }
+
+        dirty = false;
+    }
+
+    public void finish() {
+        if (dirty && dataBits.length > longInDataBitsIndex + 7) {
+            dataBits[longInDataBitsIndex] = (byte) (current >> 56 & 0xff);
+            dataBits[longInDataBitsIndex + 1] = (byte) (current >> 48 & 0xff);
+            dataBits[longInDataBitsIndex + 2] = (byte) (current >> 40 & 0xff);
+            dataBits[longInDataBitsIndex + 3] = (byte) (current >> 32 & 0xff);
+            dataBits[longInDataBitsIndex + 4] = (byte) (current >> 24 & 0xff);
+            dataBits[longInDataBitsIndex + 5] = (byte) (current >> 16 & 0xff);
+            dataBits[longInDataBitsIndex + 6] = (byte) (current >> 8 & 0xff);
+            dataBits[longInDataBitsIndex + 7] = (byte) (current & 0xff);
+        }
+    }
+
+    public void write(int value) {
+        current = current & ~(mask << bitInLongIndex) | (value & mask) << bitInLongIndex;
+        dirty = true;
+        bitInLongIndex += bitsPerObject;
+
+        if (bitInLongIndex > 63) {
+            finish();
+            bitInLongIndex -= 64;
+            longInDataBitsIndex += 8;
+            init();
+
+            if (bitInLongIndex > 0) {
+                current = current & ~(mask >>> bitsPerObject - bitInLongIndex) | (value & mask) >>> bitsPerObject - bitInLongIndex;
+                dirty = true;
+            }
+        }
+    }
+
+    public void skip() {
+        bitInLongIndex += bitsPerObject;
+
+        if (bitInLongIndex > 63) {
+            finish();
+            bitInLongIndex -= 64;
+            longInDataBitsIndex += 8;
+            init();
+        }
+    }
+}
diff --git a/src/main/java/net/minecraft/server/Chunk.java b/src/main/java/net/minecraft/server/Chunk.java
index 585de1bb2f..4e8eb137ae 100644
--- a/src/main/java/net/minecraft/server/Chunk.java
+++ b/src/main/java/net/minecraft/server/Chunk.java
@@ -535,7 +535,7 @@ public class Chunk implements IChunkAccess {
                     return null;
                 }
 
-                chunksection = new ChunkSection(j >> 4 << 4, this.world.worldProvider.g());
+                chunksection = new ChunkSection(j >> 4 << 4, this.world.worldProvider.g(), this, this.world, true); // Paper - Anti-Xray
                 this.sections[j >> 4] = chunksection;
                 flag1 = j >= l;
             }
@@ -635,7 +635,7 @@ public class Chunk implements IChunkAccess {
                     return;
                 }
 
-                chunksection = new ChunkSection(i1 << 4, flag);
+                chunksection = new ChunkSection(i1 << 4, flag, this, this.world, true); // Paper - Anti-Xray
                 this.sections[i1] = chunksection;
                 this.initLighting();
             }
diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
index 2dc5a8594a..9b4bc3ff68 100644
--- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
+++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
@@ -859,7 +859,7 @@ public class ChunkRegionLoader implements IChunkLoader, IAsyncChunkSaver {
         }
 
         ChunkConverter chunkconverter = nbttagcompound.hasKeyOfType("UpgradeData", 10) ? new ChunkConverter(nbttagcompound.getCompound("UpgradeData")) : ChunkConverter.a;
-        ProtoChunk protochunk = new ProtoChunk(i, j, chunkconverter);
+        ProtoChunk protochunk = new ProtoChunk(i, j, chunkconverter, generatoraccess); // Paper - Anti-Xray
 
         protochunk.a(abiomebase);
         protochunk.b(nbttagcompound.getLong("InhabitedTime"));
@@ -965,7 +965,7 @@ public class ChunkRegionLoader implements IChunkLoader, IAsyncChunkSaver {
         for (int i = 0; i < nbttaglist.size(); ++i) {
             NBTTagCompound nbttagcompound = nbttaglist.getCompound(i);
             byte b0 = nbttagcompound.getByte("Y");
-            ChunkSection chunksection = new ChunkSection(b0 << 4, flag1);
+            ChunkSection chunksection = new ChunkSection(b0 << 4, flag1, null, iworldreader, false); // Paper - Anti-Xray
 
             chunksection.getBlocks().a(nbttagcompound, "Palette", "BlockStates");
             chunksection.a(new NibbleArray(nbttagcompound.getByteArray("BlockLight")));
diff --git a/src/main/java/net/minecraft/server/ChunkSection.java b/src/main/java/net/minecraft/server/ChunkSection.java
index 7e4c79a1ce..bdfc7d81ff 100644
--- a/src/main/java/net/minecraft/server/ChunkSection.java
+++ b/src/main/java/net/minecraft/server/ChunkSection.java
@@ -10,9 +10,15 @@ public class ChunkSection {
     private NibbleArray emittedLight;
     private NibbleArray skyLight;
 
+    // Paper start - Anti-Xray - Support default constructor
     public ChunkSection(int i, boolean flag) {
+        this(i, flag, null, null, true);
+    }
+    // Paper end
+
+    public ChunkSection(int i, boolean flag, IChunkAccess chunk, IWorldReader world, boolean initializeBlocks) { // Paper - Anti-Xray
         this.yPos = i;
-        this.blockIds = new DataPaletteBlock<IBlockData>(GLOBAL_PALETTE, Block.REGISTRY_ID, GameProfileSerializer::d, GameProfileSerializer::a, Blocks.AIR.getBlockData());
+        this.blockIds = new DataPaletteBlock<IBlockData>(GLOBAL_PALETTE, Block.REGISTRY_ID, GameProfileSerializer::d, GameProfileSerializer::a, Blocks.AIR.getBlockData(), world instanceof GeneratorAccess ? ((GeneratorAccess) world).getMinecraftWorld().chunkPacketBlockController.getPredefinedBlockData(world, chunk, this, flag, initializeBlocks) : null, initializeBlocks); // Paper - Anti-Xray - Add predefined block data
         this.emittedLight = new NibbleArray();
         if (flag) {
             this.skyLight = new NibbleArray();
diff --git a/src/main/java/net/minecraft/server/ChunkTaskScheduler.java b/src/main/java/net/minecraft/server/ChunkTaskScheduler.java
index 95eb1a84ac..34019bd1b3 100644
--- a/src/main/java/net/minecraft/server/ChunkTaskScheduler.java
+++ b/src/main/java/net/minecraft/server/ChunkTaskScheduler.java
@@ -42,7 +42,7 @@ public class ChunkTaskScheduler extends Scheduler<ChunkCoordIntPair, ChunkStatus
 
     // CraftBukkit start
     public void forcePolluteCache(ChunkCoordIntPair chunkcoordintpair) {
-        this.progressCache.put(chunkcoordintpair.a(), new Scheduler.a(chunkcoordintpair, new ProtoChunk(chunkcoordintpair, ChunkConverter.a), ChunkStatus.EMPTY));
+        this.progressCache.put(chunkcoordintpair.a(), new Scheduler.a(chunkcoordintpair, new ProtoChunk(chunkcoordintpair, ChunkConverter.a, this.getWorld()), ChunkStatus.EMPTY)); // Paper - Anti-Xray
     }
     // CraftBukkit end
 
@@ -68,7 +68,7 @@ public class ChunkTaskScheduler extends Scheduler<ChunkCoordIntPair, ChunkStatus
                     protochunk.setLastSaved(this.c.getTime());
                     return new Scheduler.a(chunkcoordintpair, protochunk, protochunk.i());
                 } else {
-                    return new Scheduler.a(chunkcoordintpair, new ProtoChunk(chunkcoordintpair, ChunkConverter.a), ChunkStatus.EMPTY);
+                    return new Scheduler.a(chunkcoordintpair, new ProtoChunk(chunkcoordintpair, ChunkConverter.a, this.getWorld()), ChunkStatus.EMPTY); // Paper - Anti-Xray
                 }
             }) : (Scheduler.a) this.progressCache.get(chunkcoordintpair.a());
         }
diff --git a/src/main/java/net/minecraft/server/DataPaletteBlock.java b/src/main/java/net/minecraft/server/DataPaletteBlock.java
index 6e7454b134..71a3636be6 100644
--- a/src/main/java/net/minecraft/server/DataPaletteBlock.java
+++ b/src/main/java/net/minecraft/server/DataPaletteBlock.java
@@ -1,5 +1,6 @@
 package net.minecraft.server;
 
+import com.destroystokyo.paper.antixray.ChunkPacketInfo; // Paper - Anti-Xray
 import java.util.Arrays;
 import java.util.Objects;
 import java.util.concurrent.locks.ReentrantLock;
@@ -15,6 +16,7 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
     private final Function<NBTTagCompound, T> e;
     private final Function<T, NBTTagCompound> f;
     private final T g;
+    private final T[] predefinedObjects; // Paper - Anti-Xray - Add predefined objects
     protected DataBits a; protected DataBits getDataBits() { return this.a; } // Paper - OBFHELPER
     private DataPalette<T> h; private DataPalette<T> getDataPalette() { return this.h; } // Paper - OBFHELPER
     private int i; private int getBitsPerObject() { return this.i; } // Paper - OBFHELPER
@@ -39,12 +41,43 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
     }
 
     public DataPaletteBlock(DataPalette<T> datapalette, RegistryBlockID<T> registryblockid, Function<NBTTagCompound, T> function, Function<T, NBTTagCompound> function1, T object) {
+        // Paper start - Anti-Xray - Support default constructor
+        this(datapalette, registryblockid, function, function1, object, null, true);
+    }
+
+    public DataPaletteBlock(DataPalette<T> datapalette, RegistryBlockID<T> registryblockid, Function<NBTTagCompound, T> function, Function<T, NBTTagCompound> function1, T object, T[] predefinedObjects, boolean initialize) {
+        // Paper end - Anti-Xray - Add predefined objects
         this.b = datapalette;
         this.d = registryblockid;
         this.e = function;
         this.f = function1;
         this.g = (T)object;
-        this.b(4);
+        // Paper start - Anti-Xray - Add predefined objects
+        this.predefinedObjects = predefinedObjects;
+
+        if (initialize) {
+            if (predefinedObjects == null) {
+                // Default
+                this.initialize(4);
+            } else {
+                // TODO: MathHelper.d(int i) can be used here instead (see DataPaletteBlock#a(NBTTagCompound nbttagcompound, String s, String s1)) but I don't understand the implementation
+                // Count the bits of the maximum array index to initialize a data palette with enough space from the beginning
+                // The length of the array is used because air is also added to the data palette from the beginning
+                // Start with at least 4
+                int maxIndex = predefinedObjects.length >> 4;
+                int bitCount = 4;
+
+                while (maxIndex != 0) {
+                    maxIndex >>= 1;
+                    bitCount++;
+                }
+
+                // Initialize with at least 15 free indixes
+                this.initialize((1 << bitCount) - predefinedObjects.length < 16 ? bitCount + 1 : bitCount);
+                this.addPredefinedObjects();
+            }
+        }
+        // Paper end
     }
 
     private static int b(int ix, int jx, int k) {
@@ -70,12 +103,22 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
         }
     }
 
+    // Paper start - Anti-Xray - Add predefined objects
+    private void addPredefinedObjects() {
+        if (this.predefinedObjects != null && this.getDataPalette() != this.getDataPaletteGlobal()) {
+            for (int i = 0; i < this.predefinedObjects.length; i++) {
+                this.getDataPalette().getOrCreateIdFor(this.predefinedObjects[i]);
+            }
+        }
+    }
+    // Paper end
     public int onResize(int ix, T object) {
         this.b();
         DataBits databits = this.a;
         DataPalette<T> datapalette = this.h; // Paper - decompile fix
         this.b(ix);
 
+        this.addPredefinedObjects(); // Paper - Anti-Xray - Add predefined objects
         for(int jx = 0; jx < databits.b(); ++jx) {
             T object1 = datapalette.a(databits.a(jx)); // Paper - decompile fix
             if (object1 != null) {
@@ -108,11 +151,28 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
         return (T)(object == null ? this.g : object);
     }
 
-    public void writeDataPaletteBlock(PacketDataSerializer packetDataSerializer) { this.b(packetDataSerializer); } // Paper - OBFHELPER
+    // Paper start - Anti-Xray - Support default methods
+    public void writeDataPaletteBlock(PacketDataSerializer packetDataSerializer) { this.b(packetDataSerializer); }
     public void b(PacketDataSerializer packetdataserializer) {
+        this.b(packetdataserializer, null, 0);
+    }
+    // Paper end
+
+    public void writeDataPaletteBlock(PacketDataSerializer packetDataSerializer, ChunkPacketInfo<T> chunkPacketInfo, int chunkSectionIndex) { this.b(packetDataSerializer, chunkPacketInfo, chunkSectionIndex); } // Paper - OBFHELPER // Paper - Anti-Xray - Add chunk packet info
+    public void b(PacketDataSerializer packetdataserializer, ChunkPacketInfo<T> chunkPacketInfo, int chunkSectionIndex) { // Paper - Anti-Xray - Add chunk packet info
         this.b();
         packetdataserializer.writeByte(this.i);
         this.h.b(packetdataserializer);
+
+        // Paper start - Anti-Xray - Add chunk packet info
+        if (chunkPacketInfo != null) {
+            chunkPacketInfo.setBitsPerObject(chunkSectionIndex, this.getBitsPerObject());
+            chunkPacketInfo.setDataPalette(chunkSectionIndex, this.getDataPalette());
+            chunkPacketInfo.setDataBitsIndex(chunkSectionIndex, packetdataserializer.writerIndex() + PacketDataSerializer.countBytes(this.getDataBits().getDataBits().length));
+            chunkPacketInfo.setPredefinedObjects(chunkSectionIndex, this.predefinedObjects);
+        }
+        // Paper end
+
         packetdataserializer.a(this.a.a());
         this.c();
     }
@@ -120,12 +180,15 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
     public void a(NBTTagCompound nbttagcompound, String s, String s1) {
         this.b();
         NBTTagList nbttaglist = nbttagcompound.getList(s, 10);
-        int ix = Math.max(4, MathHelper.d(nbttaglist.size()));
-        if (ix != this.i) {
+        // Paper - Anti-Xray - TODO: Should this.predefinedObjects.length just be added here (faster) or should the contents be compared to calculate the size (less RAM)?
+        int ix = Math.max(4, MathHelper.d(nbttaglist.size() + (this.predefinedObjects == null ? 0 : this.predefinedObjects.length))); // Paper - Anti-Xray - Calculate the size with predefined objects
+
+        if (true || ix != this.i) { // Paper - Anti-Xray - Not initialized yet
             this.b(ix);
         }
 
         this.h.a(nbttaglist);
+        this.addPredefinedObjects(); // Paper - Anti-Xray - Add predefined objects
         long[] along = nbttagcompound.o(s1);
         int jx = along.length * 64 / 4096;
         if (this.h == this.b) {
diff --git a/src/main/java/net/minecraft/server/NetworkManager.java b/src/main/java/net/minecraft/server/NetworkManager.java
index f8facddb40..b2afec5e4b 100644
--- a/src/main/java/net/minecraft/server/NetworkManager.java
+++ b/src/main/java/net/minecraft/server/NetworkManager.java
@@ -158,8 +158,8 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
     }
 
     public void sendPacket(Packet<?> packet, @Nullable GenericFutureListener<? extends Future<? super Void>> genericfuturelistener) {
-        if (this.isConnected()) {
-            this.o();
+        if (this.isConnected() && this.sendPacketQueue() && !(packet instanceof PacketPlayOutMapChunk && !((PacketPlayOutMapChunk) packet).isReady())) { // Paper - Async-Anti-Xray - Add chunk packets which are not ready or all packets if the packet queue contains chunk packets which are not ready to the packet queue and send the packets later in the right order
+            //this.o(); // Paper - Async-Anti-Xray - Move to if statement (this.sendPacketQueue())
             this.b(packet, genericfuturelistener);
         } else {
             this.j.writeLock().lock();
@@ -214,23 +214,38 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
 
     }
 
-    private void sendPacketQueue() { this.o(); } // Paper - OBFHELPER
-    private void o() {
+    // Paper start - Async-Anti-Xray - Stop dispatching further packets and return false if the peeked packet is a chunk packet which is not ready
+    private boolean sendPacketQueue() { return this.o(); } // OBFHELPER // void -> boolean
+    private boolean o() { // void -> boolean
         if (this.channel != null && this.channel.isOpen()) {
-            this.j.readLock().lock();
+            if (this.i.isEmpty()) { // return if the packet queue is empty so that the write lock by Anti-Xray doesn't affect the vanilla performance at all
+                return true;
+            }
+
+            this.j.writeLock().lock(); // readLock -> writeLock (because of race condition between peek and poll)
 
             try {
                 while (!this.i.isEmpty()) {
-                    NetworkManager.QueuedPacket networkmanager_queuedpacket = (NetworkManager.QueuedPacket) this.i.poll();
-
-                    this.b(networkmanager_queuedpacket.a, networkmanager_queuedpacket.b);
+                    NetworkManager.QueuedPacket networkmanager_queuedpacket = (NetworkManager.QueuedPacket) this.getPacketQueue().peek(); // poll -> peek
+
+                    if (networkmanager_queuedpacket != null) { // Fix NPE (Spigot bug caused by handleDisconnection())
+                        if (networkmanager_queuedpacket.getPacket() instanceof PacketPlayOutMapChunk && !((PacketPlayOutMapChunk) networkmanager_queuedpacket.getPacket()).isReady()) { // Check if the peeked packet is a chunk packet which is not ready
+                            return false; // Return false if the peeked packet is a chunk packet which is not ready
+                        } else {
+                            this.getPacketQueue().poll(); // poll here
+                            this.dispatchPacket(networkmanager_queuedpacket.getPacket(), networkmanager_queuedpacket.getGenericFutureListener()); // dispatch the packet
+                        }
+                    }
                 }
             } finally {
-                this.j.readLock().unlock();
+                this.j.writeLock().unlock(); // readLock -> writeLock (because of race condition between peek and poll)
             }
 
         }
+
+        return true; // Return true if all packets were dispatched
     }
+    // Paper end
 
     public void a() {
         this.o();
diff --git a/src/main/java/net/minecraft/server/PacketPlayOutMapChunk.java b/src/main/java/net/minecraft/server/PacketPlayOutMapChunk.java
index 22a262bb60..40ec398eef 100644
--- a/src/main/java/net/minecraft/server/PacketPlayOutMapChunk.java
+++ b/src/main/java/net/minecraft/server/PacketPlayOutMapChunk.java
@@ -1,5 +1,6 @@
 package net.minecraft.server;
 
+import com.destroystokyo.paper.antixray.ChunkPacketInfo; // Paper - Anti-Xray
 import com.google.common.collect.Lists;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -14,17 +15,27 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
     private byte[] d; private byte[] getData() { return this.d; } // Paper - OBFHELPER
     private List<NBTTagCompound> e;
     private boolean f;
+    private volatile boolean ready = false; // Paper - Async-Anti-Xray - Ready flag for the network manager
 
     public PacketPlayOutMapChunk() {
+        this.ready = true; // Paper - Async-Anti-Xray - Set the ready flag to true
     }
 
     public PacketPlayOutMapChunk(Chunk chunk, int i) {
+        ChunkPacketInfo<IBlockData> chunkPacketInfo = chunk.world.chunkPacketBlockController.getChunkPacketInfo(this, chunk, i); // Paper - Anti-Xray - Add chunk packet info
         this.a = chunk.locX;
         this.b = chunk.locZ;
         this.f = i == 65535;
         boolean flag = chunk.getWorld().worldProvider.g();
         this.d = new byte[this.a(chunk, flag, i)];
-        this.c = this.a(new PacketDataSerializer(this.h()), chunk, flag, i);
+
+        // Paper start - Anti-Xray - Add chunk packet info
+        if (chunkPacketInfo != null) {
+            chunkPacketInfo.setData(this.getData());
+        }
+        // Paper end
+
+        this.c = this.writeChunk(new PacketDataSerializer(this.h()), chunk, flag, i, chunkPacketInfo); // Paper - Anti-Xray - Add chunk packet info
         this.e = Lists.newArrayList();
 
         for(Entry entry : chunk.getTileEntities().entrySet()) {
@@ -38,8 +49,19 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
             }
         }
 
+        chunk.world.chunkPacketBlockController.modifyBlocks(this, chunkPacketInfo); // Paper - Anti-Xray - Modify blocks
+    }
+
+    // Paper start - Async-Anti-Xray - Getter and Setter for the ready flag
+    public boolean isReady() {
+        return this.ready;
     }
 
+    public void setReady(boolean ready) {
+        this.ready = ready;
+    }
+    // Paper end
+
     public void a(PacketDataSerializer packetdataserializer) throws IOException {
         this.a = packetdataserializer.readInt();
         this.b = packetdataserializer.readInt();
@@ -86,8 +108,15 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
         return bytebuf;
     }
 
-    public int writeChunk(PacketDataSerializer packetDataSerializer, Chunk chunk, boolean writeSkyLightArray, int chunkSectionSelector) { return this.a(packetDataSerializer, chunk, writeSkyLightArray, chunkSectionSelector); } // Paper - OBFHELPER
+    // Paper start - Anti-Xray - Support default methods
+    public int writeChunk(PacketDataSerializer packetDataSerializer, Chunk chunk, boolean writeSkyLightArray, int chunkSectionSelector) { return this.a(packetDataSerializer, chunk, writeSkyLightArray, chunkSectionSelector); }
     public int a(PacketDataSerializer packetdataserializer, Chunk chunk, boolean flag, int i) {
+        return this.a(packetdataserializer, chunk, flag, i, null);
+    }
+    // Paper end
+
+    public int writeChunk(PacketDataSerializer packetDataSerializer, Chunk chunk, boolean writeSkyLightArray, int chunkSectionSelector, ChunkPacketInfo<IBlockData> chunkPacketInfo) { return this.a(packetDataSerializer, chunk, writeSkyLightArray, chunkSectionSelector, chunkPacketInfo); } // Paper - OBFHELPER // Paper - Anti-Xray - Add chunk packet info
+    public int a(PacketDataSerializer packetdataserializer, Chunk chunk, boolean flag, int i, ChunkPacketInfo<IBlockData> chunkPacketInfo) { // Paper - Anti-Xray - Add chunk packet info
         int j = 0;
         ChunkSection[] achunksection = chunk.getSections();
         int k = 0;
@@ -96,7 +125,7 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
             ChunkSection chunksection = achunksection[k];
             if (chunksection != Chunk.a && (!this.f() || !chunksection.a()) && (i & 1 << k) != 0) {
                 j |= 1 << k;
-                chunksection.getBlocks().b(packetdataserializer);
+                chunksection.getBlocks().writeDataPaletteBlock(packetdataserializer, chunkPacketInfo, k); // Paper - Anti-Xray - Add chunk packet info
                 packetdataserializer.writeBytes(chunksection.getEmittedLightArray().asBytes());
                 if (flag) {
                     packetdataserializer.writeBytes(chunksection.getSkyLightArray().asBytes());
diff --git a/src/main/java/net/minecraft/server/PlayerChunk.java b/src/main/java/net/minecraft/server/PlayerChunk.java
index a0fcac3296..2c7c8adf7c 100644
--- a/src/main/java/net/minecraft/server/PlayerChunk.java
+++ b/src/main/java/net/minecraft/server/PlayerChunk.java
@@ -118,6 +118,8 @@ public class PlayerChunk {
             return false;
         } else if (!this.chunk.isReady()) {
             return false;
+        } else if (!this.chunk.world.chunkPacketBlockController.onChunkPacketCreate(this.chunk, '\uffff', false)) { // Paper - Anti-Xray - Load nearby chunks if necessary
+            return false; // Paper - Anti-Xray - Wait and try again later
         } else {
             this.dirtyCount = 0;
             this.h = 0;
@@ -140,6 +142,7 @@ public class PlayerChunk {
 
     public void sendChunk(EntityPlayer entityplayer) {
         if (this.done) {
+            this.chunk.world.chunkPacketBlockController.onChunkPacketCreate(this.chunk, '\uffff', true); // Paper - Anti-Xray - Load nearby chunks if necessary
             entityplayer.playerConnection.sendPacket(new PacketPlayOutMapChunk(this.chunk, '\uffff'));
             this.playerChunkMap.getWorld().getTracker().a(entityplayer, this.chunk);
         }
@@ -204,6 +207,9 @@ public class PlayerChunk {
                         this.a(this.playerChunkMap.getWorld().getTileEntity(blockposition));
                     }
                 } else if (this.dirtyCount == 64) {
+                    // Paper - Anti-Xray - Loading chunks here could cause a ConcurrentModificationException #1104
+                    // Paper - Anti-Xray - TODO: Check if this is still the case for 1.13
+                    //this.chunk.world.chunkPacketBlockController.onChunkPacketCreate(this.chunk, this.h, true); // Paper - Anti-Xray - Load nearby chunks if necessary
                     this.a((Packet) (new PacketPlayOutMapChunk(this.chunk, this.h)));
                 } else {
                     this.a((Packet) (new PacketPlayOutMultiBlockChange(this.dirtyCount, this.dirtyBlocks, this.chunk)));
diff --git a/src/main/java/net/minecraft/server/PlayerInteractManager.java b/src/main/java/net/minecraft/server/PlayerInteractManager.java
index 23223e89d3..23fc4d8e14 100644
--- a/src/main/java/net/minecraft/server/PlayerInteractManager.java
+++ b/src/main/java/net/minecraft/server/PlayerInteractManager.java
@@ -207,6 +207,8 @@ public class PlayerInteractManager {
             }
 
         }
+
+        this.world.chunkPacketBlockController.onPlayerLeftClickBlock(this, blockposition, enumdirection); // Paper - Anti-Xray
     }
 
     public void a(BlockPosition blockposition) {
diff --git a/src/main/java/net/minecraft/server/ProtoChunk.java b/src/main/java/net/minecraft/server/ProtoChunk.java
index 0b79c1b16c..6554c7727a 100644
--- a/src/main/java/net/minecraft/server/ProtoChunk.java
+++ b/src/main/java/net/minecraft/server/ProtoChunk.java
@@ -40,12 +40,24 @@ public class ProtoChunk implements IChunkAccess {
     private long s;
     private final Map<WorldGenStage.Features, BitSet> t;
     private boolean u;
+    private GeneratorAccess world; // Paper - Anti-Xray
 
+    // Paper start - Anti-Xray - Support default constructors
     public ProtoChunk(int ix, int jx, ChunkConverter chunkconverter) {
-        this(new ChunkCoordIntPair(ix, jx), chunkconverter);
+        this(new ChunkCoordIntPair(ix, jx), chunkconverter, null);
     }
 
     public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter) {
+        this(chunkcoordintpair, chunkconverter, null);
+    }
+
+    public ProtoChunk(int i, int j, ChunkConverter chunkconverter, GeneratorAccess world) {
+        this(new ChunkCoordIntPair(i, j), chunkconverter, world);
+    }
+
+    public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter, GeneratorAccess world) {
+        this.world = world;
+    // Paper end
         this.d = new AtomicInteger();
         this.f = Maps.newEnumMap(HeightMap.Type.class);
         this.g = ChunkStatus.EMPTY;
@@ -132,7 +144,7 @@ public class ProtoChunk implements IChunkAccess {
                     return iblockdata;
                 }
 
-                this.j[jx >> 4] = new ChunkSection(jx >> 4 << 4, this.x());
+                this.j[jx >> 4] = new ChunkSection(jx >> 4 << 4, this.x(), this, this.world, true); // Paper - Anti-Xray
             }
 
             IBlockData iblockdata1 = this.j[jx >> 4].getType(ix & 15, jx & 15, kx & 15);
@@ -375,7 +387,7 @@ public class ProtoChunk implements IChunkAccess {
                     return;
                 }
 
-                this.j[i1] = new ChunkSection(i1 << 4, this.x());
+                this.j[i1] = new ChunkSection(i1 << 4, this.x(), this, this.world, true); // Paper - Anti-Xray
             }
 
             if (enumskyblock == EnumSkyBlock.SKY) {
diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index bb0a23fcba..d239fc6d3a 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1,6 +1,8 @@
 	package net.minecraft.server;
 
 import co.aikar.timings.Timings;
+import com.destroystokyo.paper.antixray.ChunkPacketBlockController; // Paper - Anti-Xray
+import com.destroystokyo.paper.antixray.ChunkPacketBlockControllerAntiXray; // Paper - Anti-Xray
 import com.destroystokyo.paper.event.server.ServerExceptionEvent;
 import com.destroystokyo.paper.exception.ServerInternalException;
 import com.google.common.base.MoreObjects;
@@ -144,6 +146,7 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
     public final org.spigotmc.SpigotWorldConfig spigotConfig; // Spigot
 
     public final com.destroystokyo.paper.PaperWorldConfig paperConfig; // Paper
+    public final ChunkPacketBlockController chunkPacketBlockController; // Paper - Anti-Xray
 
     public final co.aikar.timings.WorldTimingsHandler timings; // Paper
     public boolean guardEntityList; // Spigot // Paper - public
@@ -169,6 +172,7 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
     protected World(IDataManager idatamanager, @Nullable PersistentCollection persistentcollection, WorldData worlddata, WorldProvider worldprovider, MethodProfiler methodprofiler, boolean flag, ChunkGenerator gen, org.bukkit.World.Environment env) {
         this.spigotConfig = new org.spigotmc.SpigotWorldConfig( worlddata.getName() ); // Spigot
         this.paperConfig = new com.destroystokyo.paper.PaperWorldConfig(worlddata.getName(), this.spigotConfig); // Paper
+        this.chunkPacketBlockController = this.paperConfig.antiXray ? new ChunkPacketBlockControllerAntiXray(this.paperConfig) : ChunkPacketBlockController.NO_OPERATION_INSTANCE; // Paper - Anti-Xray
         this.generator = gen;
         this.world = new CraftWorld((WorldServer) this, gen, env);
         this.ticksPerAnimalSpawns = this.getServer().getTicksPerAnimalSpawns(); // CraftBukkit
@@ -411,6 +415,7 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
             // CraftBukkit end
 
             IBlockData iblockdata1 = chunk.setType(blockposition, iblockdata, (i & 64) != 0, (i & 1024) == 0); // CraftBukkit custom NO_PLACE flag
+            this.chunkPacketBlockController.onBlockChange(this, blockposition, iblockdata, iblockdata1, i); // Paper - Anti-Xray
 
             if (iblockdata1 == null) {
                 // CraftBukkit start - remove blockstate if failed
diff --git a/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java b/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java
index 550416bef0..923d1b2821 100644
--- a/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java
+++ b/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java
@@ -17,9 +17,11 @@ import org.bukkit.material.MaterialData;
 public final class CraftChunkData implements ChunkGenerator.ChunkData {
     private final int maxHeight;
     private final ChunkSection[] sections;
+    private World world; // Paper - Anti-Xray
 
     public CraftChunkData(World world) {
         this(world.getMaxHeight());
+        this.world = world; // Paper - Anti-Xray
     }
 
     /* pp for tests */ CraftChunkData(int maxHeight) {
@@ -145,7 +147,7 @@ public final class CraftChunkData implements ChunkGenerator.ChunkData {
     private ChunkSection getChunkSection(int y, boolean create) {
         ChunkSection section = sections[y >> 4];
         if (create && section == null) {
-            sections[y >> 4] = section = new ChunkSection(y, create);
+            sections[y >> 4] = section = new ChunkSection(y, create, null, world instanceof org.bukkit.craftbukkit.CraftWorld ? ((org.bukkit.craftbukkit.CraftWorld) world).getHandle() : null, true); // Paper - Anti-Xray
         }
         return section;
     }
-- 
2.19.1