Paper/Spigot-Server-Patches/0363-Anti-Xray.patch

From 0000000000000000000000000000000000000000 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 1278d09f70c1e97607ef20d87a178dc252c7f723..c45493e88bf7e8811be2759ff9ac19e3fe9d938a 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -1,7 +1,9 @@
 package com.destroystokyo.paper;
 
+import java.util.Arrays;
 import java.util.List;
 
+import com.destroystokyo.paper.antixray.ChunkPacketBlockControllerAntiXray.EngineMode;
 import org.bukkit.Bukkit;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.spigotmc.SpigotWorldConfig;
@@ -461,4 +463,38 @@ public class PaperWorldConfig {
     private void maxAutoSaveChunksPerTick() {
         maxAutoSaveChunksPerTick = getInt("max-auto-save-chunks-per-tick", 24);
     }
+
+    public boolean antiXray;
+    public EngineMode engineMode;
+    public int maxChunkSectionIndex;
+    public int updateRadius;
+    public boolean lavaObscures;
+    public boolean usePermission;
+    public List<String> hiddenBlocks;
+    public List<String> replacementBlocks;
+    private void antiXray() {
+        antiXray = getBoolean("anti-xray.enabled", false);
+        engineMode = EngineMode.getById(getInt("anti-xray.engine-mode", EngineMode.HIDE.getId()));
+        engineMode = engineMode == null ? EngineMode.HIDE : engineMode;
+        maxChunkSectionIndex = getInt("anti-xray.max-chunk-section-index", 3);
+        maxChunkSectionIndex = maxChunkSectionIndex > 15 ? 15 : maxChunkSectionIndex;
+        updateRadius = getInt("anti-xray.update-radius", 2);
+        lavaObscures = getBoolean("anti-xray.lava-obscures", false);
+        usePermission = getBoolean("anti-xray.use-permission", false);
+        hiddenBlocks = getList("anti-xray.hidden-blocks", Arrays.asList("gold_ore", "iron_ore", "coal_ore", "lapis_ore", "mossy_cobblestone", "obsidian", "chest", "diamond_ore", "redstone_ore", "clay", "emerald_ore", "ender_chest"));
+        replacementBlocks = getList("anti-xray.replacement-blocks", Arrays.asList("stone", "oak_planks"));
+        if (PaperConfig.version < 19) {
+            hiddenBlocks.remove("lit_redstone_ore");
+            int index = replacementBlocks.indexOf("planks");
+            if (index != -1) {
+                replacementBlocks.set(index, "oak_planks");
+            }
+            set("anti-xray.hidden-blocks", hiddenBlocks);
+            set("anti-xray.replacement-blocks", replacementBlocks);
+        }
+        log("Anti-Xray: " + (antiXray ? "enabled" : "disabled") + " / Engine Mode: " + engineMode.getDescription() + " / Up to " + ((maxChunkSectionIndex + 1) * 16) + " blocks / Update Radius: " + updateRadius);
+        if (antiXray && usePermission) {
+            Bukkit.getLogger().warning("You have enabled permission-based Anti-Xray checking - depending on your permission plugin, this may cause performance issues");
+        }
+    }
 }
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 0000000000000000000000000000000000000000..83a023ae018cbb79b5f151b1c7a5c8ba0c3bf1bf
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockController.java
@@ -0,0 +1,45 @@
+package com.destroystokyo.paper.antixray;
+
+import net.minecraft.core.BlockPosition;
+import net.minecraft.core.EnumDirection;
+import net.minecraft.network.protocol.game.PacketPlayOutMapChunk;
+import net.minecraft.server.level.EntityPlayer;
+import net.minecraft.server.level.PlayerInteractManager;
+import net.minecraft.world.level.World;
+import net.minecraft.world.level.block.state.IBlockData;
+import net.minecraft.world.level.chunk.Chunk;
+import net.minecraft.world.level.chunk.ChunkSection;
+import net.minecraft.world.level.chunk.IChunkAccess;
+
+public class ChunkPacketBlockController {
+
+    public static final ChunkPacketBlockController NO_OPERATION_INSTANCE = new ChunkPacketBlockController();
+
+    protected ChunkPacketBlockController() {
+
+    }
+
+    public IBlockData[] getPredefinedBlockData(World world, IChunkAccess chunk, ChunkSection chunkSection, boolean initializeBlocks) {
+        return null;
+    }
+
+    public boolean shouldModify(EntityPlayer entityPlayer, Chunk chunk, int chunkSectionSelector) {
+        return false;
+    }
+
+    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 0000000000000000000000000000000000000000..cd3b5b62d470ab6753b44f9b13dcf5522e4cbd15
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java
@@ -0,0 +1,650 @@
+package com.destroystokyo.paper.antixray;
+
+import java.util.ArrayList;
+import java.util.LinkedHashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.IntSupplier;
+
+import net.minecraft.core.BlockPosition;
+import net.minecraft.core.EnumDirection;
+import net.minecraft.core.IRegistry;
+import net.minecraft.network.protocol.game.PacketPlayOutMapChunk;
+import net.minecraft.resources.MinecraftKey;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.EntityPlayer;
+import net.minecraft.server.level.PlayerInteractManager;
+import net.minecraft.server.level.WorldServer;
+import net.minecraft.world.level.ChunkCoordIntPair;
+import net.minecraft.world.level.World;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.IBlockData;
+import net.minecraft.world.level.chunk.Chunk;
+import net.minecraft.world.level.chunk.ChunkEmpty;
+import net.minecraft.world.level.chunk.ChunkSection;
+import net.minecraft.world.level.chunk.DataPalette;
+import net.minecraft.world.level.chunk.IChunkAccess;
+import org.bukkit.Bukkit;
+import org.bukkit.World.Environment;
+
+import com.destroystokyo.paper.PaperWorldConfig;
+
+public final class ChunkPacketBlockControllerAntiXray extends ChunkPacketBlockController {
+
+    private final Executor executor;
+    private final EngineMode engineMode;
+    private final int maxChunkSectionIndex;
+    private final int updateRadius;
+    private final boolean usePermission;
+    private final IBlockData[] predefinedBlockData;
+    private final IBlockData[] predefinedBlockDataFull;
+    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(World world, Executor executor) {
+        PaperWorldConfig paperWorldConfig = world.paperConfig;
+        engineMode = paperWorldConfig.engineMode;
+        maxChunkSectionIndex = paperWorldConfig.maxChunkSectionIndex;
+        updateRadius = paperWorldConfig.updateRadius;
+        usePermission = paperWorldConfig.usePermission;
+
+        this.executor = executor;
+
+        List<String> toObfuscate;
+
+        if (engineMode == EngineMode.HIDE) {
+            toObfuscate = paperWorldConfig.hiddenBlocks;
+            predefinedBlockData = null;
+            predefinedBlockDataFull = 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 {
+            toObfuscate = new ArrayList<>(paperWorldConfig.replacementBlocks);
+            List<IBlockData> predefinedBlockDataList = new LinkedList<IBlockData>();
+
+            for (String id : paperWorldConfig.hiddenBlocks) {
+                Block block = IRegistry.BLOCK.getOptional(new MinecraftKey(id)).orElse(null);
+
+                if (block != null && !block.isTileEntity()) {
+                    toObfuscate.add(id);
+                    predefinedBlockDataList.add(block.getBlockData());
+                }
+            }
+
+            // The doc of the LinkedHashSet(Collection<? extends E> c) constructor doesn't specify that the insertion order is the predictable iteration order of the specified Collection, although it is in the implementation
+            Set<IBlockData> predefinedBlockDataSet = new LinkedHashSet<IBlockData>();
+            // Therefore addAll(Collection<? extends E> c) is used, which guarantees this order in the doc
+            predefinedBlockDataSet.addAll(predefinedBlockDataList);
+            predefinedBlockData = predefinedBlockDataSet.size() == 0 ? new IBlockData[] {Blocks.DIAMOND_ORE.getBlockData()} : predefinedBlockDataSet.toArray(new IBlockData[0]);
+            predefinedBlockDataFull = predefinedBlockDataSet.size() == 0 ? new IBlockData[] {Blocks.DIAMOND_ORE.getBlockData()} : predefinedBlockDataList.toArray(new IBlockData[0]);
+            predefinedBlockDataStone = null;
+            predefinedBlockDataNetherrack = null;
+            predefinedBlockDataEndStone = null;
+            predefinedBlockDataBitsGlobal = new int[predefinedBlockDataFull.length];
+
+            for (int i = 0; i < predefinedBlockDataFull.length; i++) {
+                predefinedBlockDataBitsGlobal[i] = ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(predefinedBlockDataFull[i]);
+            }
+
+            predefinedBlockDataBitsStoneGlobal = null;
+            predefinedBlockDataBitsNetherrackGlobal = null;
+            predefinedBlockDataBitsEndStoneGlobal = null;
+        }
+
+        for (String id : toObfuscate) {
+            Block block = IRegistry.BLOCK.getOptional(new MinecraftKey(id)).orElse(null);
+
+            // Don't obfuscate air because air causes unnecessary block updates and causes block updates to fail in the void
+            if (block != null && !block.getBlockData().isAir()) {
+                // Replace all block states of a specified block
+                // No OBFHELPER for nms.BlockStateList#a() due to too many decompile errors
+                // The OBFHELPER should be getBlockDataList()
+                for (IBlockData blockData : block.getStates().a()) {
+                    obfuscateGlobal[ChunkSection.GLOBAL_PALETTE.getOrCreateIdFor(blockData)] = true;
+                }
+            }
+        }
+
+        ChunkEmpty emptyChunk = new ChunkEmpty(world, new ChunkCoordIntPair(0, 0));
+        BlockPosition zeroPos = new BlockPosition(0, 0, 0);
+
+        for (int i = 0; i < solidGlobal.length; i++) {
+            IBlockData blockData = ChunkSection.GLOBAL_PALETTE.getObject(i);
+
+            if (blockData != null) {
+                solidGlobal[i] = blockData.isOccluding(emptyChunk, zeroPos)
+                    && blockData.getBlock() != Blocks.SPAWNER && blockData.getBlock() != Blocks.BARRIER && blockData.getBlock() != Blocks.SHULKER_BOX && blockData.getBlock() != Blocks.SLIME_BLOCK || paperWorldConfig.lavaObscures && blockData == Blocks.LAVA.getBlockData();
+                // Comparing blockData == Blocks.LAVA.getBlockData() instead of blockData.getBlock() == Blocks.LAVA ensures that only "stationary lava" is used
+                // shulker box checks TE.
+            }
+        }
+
+        this.maxBlockYUpdatePosition = (maxChunkSectionIndex + 1) * 16 + updateRadius - 1;
+    }
+
+    private int getPredefinedBlockDataFullLength() {
+        return engineMode == EngineMode.HIDE ? 1 : predefinedBlockDataFull.length;
+    }
+
+    @Override
+    public IBlockData[] getPredefinedBlockData(World world, IChunkAccess chunk, ChunkSection chunkSection, 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:
+                    switch (world.getWorld().getEnvironment()) {
+                        case NETHER:
+                            return predefinedBlockDataNetherrack;
+                        case THE_END:
+                            return predefinedBlockDataEndStone;
+                        default:
+                            return predefinedBlockDataStone;
+                    }
+                default:
+                    return predefinedBlockData;
+            }
+        }
+
+        return null;
+    }
+
+    @Override
+    public boolean shouldModify(EntityPlayer entityPlayer, Chunk chunk, int chunkSectionSelector) {
+        return !usePermission || !entityPlayer.getBukkitEntity().hasPermission("paper.antixray.bypass");
+    }
+
+    @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
+        // Note: As of 1.14 this has to be moved later due to the chunk system.
+        ChunkPacketInfoAntiXray chunkPacketInfoAntiXray = new ChunkPacketInfoAntiXray(packetPlayOutMapChunk, chunk, chunkSectionSelector, this);
+        return chunkPacketInfoAntiXray;
+    }
+
+    @Override
+    public void modifyBlocks(PacketPlayOutMapChunk packetPlayOutMapChunk, ChunkPacketInfo<IBlockData> chunkPacketInfo) {
+        if (chunkPacketInfo == null) {
+            packetPlayOutMapChunk.setReady(true);
+            return;
+        }
+
+        if (!Bukkit.isPrimaryThread()) {
+            // plugins?
+            MinecraftServer.getServer().scheduleOnMain(() -> {
+                this.modifyBlocks(packetPlayOutMapChunk, chunkPacketInfo);
+            });
+            return;
+        }
+
+        Chunk chunk = chunkPacketInfo.getChunk();
+        int x = chunk.getPos().x;
+        int z = chunk.getPos().z;
+        WorldServer world = (WorldServer)chunk.world;
+        ((ChunkPacketInfoAntiXray) chunkPacketInfo).setNearbyChunks(
+            (Chunk) world.getChunkIfLoadedImmediately(x - 1, z),
+            (Chunk) world.getChunkIfLoadedImmediately(x + 1, z),
+            (Chunk) world.getChunkIfLoadedImmediately(x, z - 1),
+            (Chunk) world.getChunkIfLoadedImmediately(x, z + 1));
+
+        executor.execute((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 (even without ThreadLocal)
+    // If an ExecutorService with multiple threads is used, ThreadLocal must be used here
+    private final ThreadLocal<int[]> predefinedBlockDataBits = ThreadLocal.withInitial(() -> new int[getPredefinedBlockDataFullLength()]);
+    private static final ThreadLocal<boolean[]> solid = ThreadLocal.withInitial(() -> new boolean[Block.REGISTRY_ID.size()]);
+    private static final ThreadLocal<boolean[]> obfuscate = ThreadLocal.withInitial(() -> new boolean[Block.REGISTRY_ID.size()]);
+    // These boolean arrays represent chunk layers, true means don't obfuscate, false means obfuscate
+    private static final ThreadLocal<boolean[][]> current = ThreadLocal.withInitial(() -> new boolean[16][16]);
+    private static final ThreadLocal<boolean[][]> next = ThreadLocal.withInitial(() -> new boolean[16][16]);
+    private static final ThreadLocal<boolean[][]> nextNext = ThreadLocal.withInitial(() -> new boolean[16][16]);
+
+    public void obfuscate(ChunkPacketInfoAntiXray chunkPacketInfoAntiXray) {
+        int[] predefinedBlockDataBits = this.predefinedBlockDataBits.get();
+        boolean[] solid = this.solid.get();
+        boolean[] obfuscate = this.obfuscate.get();
+        boolean[][] current = this.current.get();
+        boolean[][] next = this.next.get();
+        boolean[][] nextNext = this.nextNext.get();
+        // dataBitsReader, dataBitsWriter and nearbyChunkSections could also be reused (with ThreadLocal if necessary) but it's not worth it
+        DataBitsReader dataBitsReader = new DataBitsReader();
+        DataBitsWriter dataBitsWriter = new DataBitsWriter();
+        ChunkSection[] nearbyChunkSections = new ChunkSection[4];
+        boolean[] solidTemp = null;
+        boolean[] obfuscateTemp = null;
+        dataBitsReader.setDataBits(chunkPacketInfoAntiXray.getData());
+        dataBitsWriter.setDataBits(chunkPacketInfoAntiXray.getData());
+        int numberOfBlocks = predefinedBlockDataBits.length;
+        // Keep the lambda expressions as simple as possible. They are used very frequently.
+        IntSupplier random = numberOfBlocks == 1 ? (() -> 0) : new IntSupplier() {
+            private int state;
+
+            {
+                while ((state = ThreadLocalRandom.current().nextInt()) == 0);
+            }
+
+            @Override
+            public int getAsInt() {
+                // https://en.wikipedia.org/wiki/Xorshift
+                state ^= state << 13;
+                state ^= state >>> 17;
+                state ^= state << 5;
+                // https://www.pcg-random.org/posts/bounded-rands.html
+                return (int) ((Integer.toUnsignedLong(state) * numberOfBlocks) >>> 32);
+            }
+        };
+
+        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 {
+                    // If it's this.predefinedBlockData, use this.predefinedBlockDataFull instead
+                    IBlockData[] predefinedBlockDataFull = chunkPacketInfoAntiXray.getPredefinedObjects(chunkSectionIndex) == predefinedBlockData ? this.predefinedBlockDataFull : chunkPacketInfoAntiXray.getPredefinedObjects(chunkSectionIndex);
+                    predefinedBlockDataBitsTemp = predefinedBlockDataBits;
+
+                    for (int i = 0; i < predefinedBlockDataBitsTemp.length; i++) {
+                        predefinedBlockDataBitsTemp[i] = chunkPacketInfoAntiXray.getDataPalette(chunkSectionIndex).getOrCreateIdFor(predefinedBlockDataFull[i]);
+                    }
+                }
+
+                dataBitsWriter.setIndex(chunkPacketInfoAntiXray.getDataBitsIndex(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.getDataBitsIndex(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, random);
+                }
+
+                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;
+                    obfuscateLayer(y, dataBitsReader, dataBitsWriter, solidTemp, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, nearbyChunkSections, random);
+                }
+
+                // 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;
+                        obfuscateLayer(15, dataBitsReader, dataBitsWriter, solid, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, nearbyChunkSections, random);
+                    }
+                } 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.getDataBitsIndex(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;
+                    obfuscateLayer(15, dataBitsReader, dataBitsWriter, solidTemp, obfuscateTemp, predefinedBlockDataBitsTemp, current, next, nextNext, nearbyChunkSections, random);
+                }
+
+                dataBitsWriter.finish();
+            }
+        }
+
+        chunkPacketInfoAntiXray.getPacketPlayOutMapChunk().setReady(true);
+    }
+
+    private void obfuscateLayer(int y, DataBitsReader dataBitsReader, DataBitsWriter dataBitsWriter, boolean[] solid, boolean[] obfuscate, int[] predefinedBlockDataBits, boolean[][] current, boolean[][] next, boolean[][] nextNext, ChunkSection[] nearbyChunkSections, IntSupplier random) {
+        // 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 {
+                dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+            }
+        }
+
+        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 {
+                    dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+                }
+            }
+
+            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 {
+                dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+            }
+        }
+
+        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 {
+                    dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+                }
+            }
+
+            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 {
+                        dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+                    }
+                }
+
+                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 {
+                    dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+                }
+            }
+
+            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 {
+                dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+            }
+        }
+
+        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 {
+                    dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+                }
+            }
+
+            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 {
+                dataBitsWriter.write(predefinedBlockDataBits[random.getAsInt()]);
+            }
+        }
+
+        if (!obfuscate[dataBits]) {
+            next[15][15] = true;
+        }
+    }
+
+    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);
+            ((WorldServer)world).getChunkProvider().flagDirty(blockPosition); // We only need to re-send to client
+        }
+    }
+
+    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;
+        }
+    }
+}
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 0000000000000000000000000000000000000000..22c9adefc3e51e9e4b8d611a40d1497d2a16a8d2
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfo.java
@@ -0,0 +1,81 @@
+package com.destroystokyo.paper.antixray;
+
+import net.minecraft.network.protocol.game.PacketPlayOutMapChunk;
+import net.minecraft.world.level.chunk.Chunk;
+import net.minecraft.world.level.chunk.DataPalette;
+
+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 getDataBitsIndex(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 0000000000000000000000000000000000000000..4b64964e52b11bea4d2c0d0f64f55ad08d2189be
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketInfoAntiXray.java
@@ -0,0 +1,30 @@
+package com.destroystokyo.paper.antixray;
+
+import net.minecraft.network.protocol.game.PacketPlayOutMapChunk;
+import net.minecraft.world.level.block.state.IBlockData;
+import net.minecraft.world.level.chunk.Chunk;
+
+public final 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 0000000000000000000000000000000000000000..298ea423084dbcc1b61f991bcd82b8ae51bf0977
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/DataBitsReader.java
@@ -0,0 +1,51 @@
+package com.destroystokyo.paper.antixray;
+
+public final 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() {
+        if (bitInLongIndex + bitsPerObject > 64) {
+            bitInLongIndex = 0;
+            longInDataBitsIndex += 8;
+            init();
+        }
+
+        int value = (int) (current >>> bitInLongIndex) & mask;
+        bitInLongIndex += bitsPerObject;
+        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 0000000000000000000000000000000000000000..333763936897befda5bb6c077944d2667f922799
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/antixray/DataBitsWriter.java
@@ -0,0 +1,79 @@
+package com.destroystokyo.paper.antixray;
+
+public final 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) {
+        if (bitInLongIndex + bitsPerObject > 64) {
+            finish();
+            bitInLongIndex = 0;
+            longInDataBitsIndex += 8;
+            init();
+        }
+
+        current = current & ~(mask << bitInLongIndex) | (value & mask) << bitInLongIndex;
+        dirty = true;
+        bitInLongIndex += bitsPerObject;
+    }
+
+    public void skip() {
+        bitInLongIndex += bitsPerObject;
+
+        if (bitInLongIndex > 64) {
+            finish();
+            bitInLongIndex = bitsPerObject;
+            longInDataBitsIndex += 8;
+            init();
+        }
+    }
+}
diff --git a/src/main/java/net/minecraft/network/protocol/game/PacketPlayOutMapChunk.java b/src/main/java/net/minecraft/network/protocol/game/PacketPlayOutMapChunk.java
index a7d10d124021f3427f23fcd533f885367b64515c..3047cf8c4ec1b664d6b790f18d2b1657e4b00435 100644
--- a/src/main/java/net/minecraft/network/protocol/game/PacketPlayOutMapChunk.java
+++ b/src/main/java/net/minecraft/network/protocol/game/PacketPlayOutMapChunk.java
@@ -1,5 +1,6 @@
 package net.minecraft.network.protocol.game;
 
+import com.destroystokyo.paper.antixray.ChunkPacketInfo; // Paper - Anti-Xray - Add chunk packet info
 import com.google.common.collect.Lists;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -16,6 +17,7 @@ import net.minecraft.network.protocol.Packet;
 import net.minecraft.world.level.ChunkCoordIntPair;
 import net.minecraft.world.level.block.entity.TileEntity;
 import net.minecraft.world.level.block.entity.TileEntitySkull;
+import net.minecraft.world.level.block.state.IBlockData;
 import net.minecraft.world.level.chunk.BiomeStorage;
 import net.minecraft.world.level.chunk.Chunk;
 import net.minecraft.world.level.chunk.ChunkSection;
@@ -33,7 +35,13 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
     private List<NBTTagCompound> g;
     private boolean h;
 
-    public PacketPlayOutMapChunk() {}
+    // Paper start - Async-Anti-Xray - Set the ready flag to true
+    private volatile boolean ready; // Paper - Async-Anti-Xray - Ready flag for the network manager
+    public PacketPlayOutMapChunk() {
+        this.ready = true;
+    }
+    // Paper end
+
     // Paper start
     private final java.util.List<Packet> extraPackets = new java.util.ArrayList<>();
     private static final int TE_LIMIT = Integer.getInteger("Paper.excessiveTELimit", 750);
@@ -43,7 +51,11 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
         return extraPackets;
     }
     // Paper end
-    public PacketPlayOutMapChunk(Chunk chunk, int i) {
+    // Paper start - Anti-Xray - Add chunk packet info
+    @Deprecated public PacketPlayOutMapChunk(Chunk chunk, int i) { this(chunk, i, true); } // Notice for updates: Please make sure this constructor isn't used anywhere
+    public PacketPlayOutMapChunk(Chunk chunk, int i, boolean modifyBlocks) {
+        ChunkPacketInfo<IBlockData> chunkPacketInfo = modifyBlocks ? chunk.world.chunkPacketBlockController.getChunkPacketInfo(this, chunk, i) : null;
+        // Paper end
         ChunkCoordIntPair chunkcoordintpair = chunk.getPos();
 
         this.a = chunkcoordintpair.x;
@@ -66,7 +78,12 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
         }
 
         this.f = new byte[this.a(chunk, i)];
-        this.c = this.a(new PacketDataSerializer(this.j()), chunk, i);
+        // Paper start - Anti-Xray - Add chunk packet info
+        if (chunkPacketInfo != null) {
+            chunkPacketInfo.setData(this.getData());
+        }
+        this.c = this.writeChunk(new PacketDataSerializer(this.j()), chunk, i, chunkPacketInfo);
+        // Paper end
         this.g = Lists.newArrayList();
         iterator = chunk.getTileEntities().entrySet().iterator();
         int totalTileEntities = 0; // Paper
@@ -93,8 +110,19 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
                 this.g.add(nbttagcompound);
             }
         }
+        chunk.world.chunkPacketBlockController.modifyBlocks(this, chunkPacketInfo); // Paper - Anti-Xray - Modify blocks
+    }
 
+    // Paper start - Async-Anti-Xray - Getter and Setter for the ready flag
+    @Override
+    public boolean isReady() {
+        return this.ready;
+    }
+
+    public void setReady(boolean ready) {
+        this.ready = ready;
     }
+    // Paper end
 
     @Override
     public void a(PacketDataSerializer packetdataserializer) throws IOException {
@@ -160,8 +188,12 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
         return bytebuf;
     }
 
-    public int writeChunk(PacketDataSerializer packetDataSerializer, Chunk chunk, int chunkSectionSelector) { return this.a(packetDataSerializer, chunk, chunkSectionSelector); } // Paper - OBFHELPER
-    public int a(PacketDataSerializer packetdataserializer, Chunk chunk, int i) {
+    // Paper start - Anti-Xray - Add chunk packet info
+    @Deprecated public int writeChunk(PacketDataSerializer packetDataSerializer, Chunk chunk, int chunkSectionSelector) { return this.a(packetDataSerializer, chunk, chunkSectionSelector); } // OBFHELPER // Notice for updates: Please make sure this method isn't used anywhere
+    @Deprecated public int a(PacketDataSerializer packetdataserializer, Chunk chunk, int i) { return this.writeChunk(packetdataserializer, chunk, i, null); } // Notice for updates: Please make sure this method isn't used anywhere
+    public int writeChunk(PacketDataSerializer packetDataSerializer, Chunk chunk, int chunkSectionSelector, ChunkPacketInfo<IBlockData> chunkPacketInfo) { return this.a(packetDataSerializer, chunk, chunkSectionSelector, chunkPacketInfo); } // OBFHELPER
+    public int a(PacketDataSerializer packetdataserializer, Chunk chunk, int i, ChunkPacketInfo<IBlockData> chunkPacketInfo) {
+        // Paper end
         int j = 0;
         ChunkSection[] achunksection = chunk.getSections();
         int k = 0;
@@ -171,7 +203,7 @@ public class PacketPlayOutMapChunk implements Packet<PacketListenerPlayOut> {
 
             if (chunksection != Chunk.a && (!this.f() || !chunksection.c()) && (i & 1 << k) != 0) {
                 j |= 1 << k;
-                chunksection.b(packetdataserializer);
+                chunksection.writeChunkSection(packetdataserializer, chunkPacketInfo); // Paper - Anti-Xray - Add chunk packet info
             }
         }
 
diff --git a/src/main/java/net/minecraft/server/level/PlayerChunkMap.java b/src/main/java/net/minecraft/server/level/PlayerChunkMap.java
index 1f32ab230d650bb5f652efbacdd5e4b90dc4de89..71c2792d7eede35485cc36ac929cf295bcd4646b 100644
--- a/src/main/java/net/minecraft/server/level/PlayerChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/PlayerChunkMap.java
@@ -656,7 +656,7 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
             }
 
             this.g(chunkcoordintpair);
-            return Either.left(new ProtoChunk(chunkcoordintpair, ChunkConverter.a));
+            return Either.left(new ProtoChunk(chunkcoordintpair, ChunkConverter.a, this.world)); // Paper - Anti-Xray - Add parameter
         }, this.executor);
     }
 
@@ -1396,9 +1396,10 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
 
     }
 
+    private final void sendChunk(EntityPlayer entityplayer, Packet<?>[] apacket, Chunk chunk) { this.a(entityplayer, apacket, chunk); } // Paper - OBFHELPER
     private void a(EntityPlayer entityplayer, Packet<?>[] apacket, Chunk chunk) {
         if (apacket[0] == null) {
-            apacket[0] = new PacketPlayOutMapChunk(chunk, 65535);
+            apacket[0] = new PacketPlayOutMapChunk(chunk, 65535, chunk.world.chunkPacketBlockController.shouldModify(entityplayer, chunk, 65535)); // Paper - Anti-Xray - Bypass
             apacket[1] = new PacketPlayOutLightUpdate(chunk.getPos(), this.lightEngine, true);
         }
 
diff --git a/src/main/java/net/minecraft/server/level/PlayerInteractManager.java b/src/main/java/net/minecraft/server/level/PlayerInteractManager.java
index d86b1e528b53db809ac993aa2f1d2799d4f1a574..fbd8a6985a261396789c87e4b687140bd49cea0d 100644
--- a/src/main/java/net/minecraft/server/level/PlayerInteractManager.java
+++ b/src/main/java/net/minecraft/server/level/PlayerInteractManager.java
@@ -309,6 +309,8 @@ public class PlayerInteractManager {
             }
 
         }
+
+        this.world.chunkPacketBlockController.onPlayerLeftClickBlock(this, blockposition, enumdirection); // Paper - Anti-Xray
     }
 
     public void a(BlockPosition blockposition, PacketPlayInBlockDig.EnumPlayerDigType packetplayinblockdig_enumplayerdigtype, String s) {
diff --git a/src/main/java/net/minecraft/server/level/WorldServer.java b/src/main/java/net/minecraft/server/level/WorldServer.java
index 735da5729c16940e3d8877f32a40342b9d1e989d..caf3d4df460d2d6dad6e68a68e1256e3603e3891 100644
--- a/src/main/java/net/minecraft/server/level/WorldServer.java
+++ b/src/main/java/net/minecraft/server/level/WorldServer.java
@@ -210,7 +210,7 @@ public class WorldServer extends World implements GeneratorAccessSeed {
 
     // Add env and gen to constructor, WorldData -> WorldDataServer
     public WorldServer(MinecraftServer minecraftserver, Executor executor, Convertable.ConversionSession convertable_conversionsession, IWorldDataServer iworlddataserver, ResourceKey<World> resourcekey, DimensionManager dimensionmanager, WorldLoadListener worldloadlistener, ChunkGenerator chunkgenerator, boolean flag, long i, List<MobSpawner> list, boolean flag1, org.bukkit.World.Environment env, org.bukkit.generator.ChunkGenerator gen) {
-        super(iworlddataserver, resourcekey, dimensionmanager, minecraftserver::getMethodProfiler, false, flag, i, gen, env);
+        super(iworlddataserver, resourcekey, dimensionmanager, minecraftserver::getMethodProfiler, false, flag, i, gen, env, executor); // Paper pass executor
         this.pvpMode = minecraftserver.getPVP();
         convertable = convertable_conversionsession;
         uuid = WorldUUID.getUUID(convertable_conversionsession.folder.toFile());
diff --git a/src/main/java/net/minecraft/world/level/World.java b/src/main/java/net/minecraft/world/level/World.java
index 12ac3608736b45447afe6b0d35ead1441390be5e..15da3511a9e57c320f4cf409852bee07109095bc 100644
--- a/src/main/java/net/minecraft/world/level/World.java
+++ b/src/main/java/net/minecraft/world/level/World.java
@@ -2,6 +2,8 @@ package net.minecraft.world.level;
 
 import co.aikar.timings.Timing;
 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 GeneratorAccess, AutoCloseable {
     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 static BlockPosition lastPhysicsProblem; // Spigot
@@ -165,9 +168,10 @@ public abstract class World implements GeneratorAccess, AutoCloseable {
         return typeKey;
     }
 
-    protected World(WorldDataMutable worlddatamutable, ResourceKey<World> resourcekey, final DimensionManager dimensionmanager, Supplier<GameProfilerFiller> supplier, boolean flag, boolean flag1, long i, org.bukkit.generator.ChunkGenerator gen, org.bukkit.World.Environment env) {
+    protected World(WorldDataMutable worlddatamutable, ResourceKey<World> resourcekey, final DimensionManager dimensionmanager, Supplier<GameProfilerFiller> supplier, boolean flag, boolean flag1, long i, org.bukkit.generator.ChunkGenerator gen, org.bukkit.World.Environment env, java.util.concurrent.Executor executor) { // Paper
         this.spigotConfig = new org.spigotmc.SpigotWorldConfig(((net.minecraft.world.level.storage.WorldDataServer) worlddatamutable).getName()); // Spigot
         this.paperConfig = new com.destroystokyo.paper.PaperWorldConfig(((net.minecraft.world.level.storage.WorldDataServer) worlddatamutable).getName(), this.spigotConfig); // Paper
+        this.chunkPacketBlockController = this.paperConfig.antiXray ? new ChunkPacketBlockControllerAntiXray(this, executor) : ChunkPacketBlockController.NO_OPERATION_INSTANCE; // Paper - Anti-Xray
         this.generator = gen;
         this.world = new CraftWorld((WorldServer) this, gen, env);
         this.ticksPerAnimalSpawns = this.getServer().getTicksPerAnimalSpawns(); // CraftBukkit
@@ -433,6 +437,7 @@ public abstract class World implements GeneratorAccess, AutoCloseable {
             // 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 (or the same)
diff --git a/src/main/java/net/minecraft/world/level/chunk/Chunk.java b/src/main/java/net/minecraft/world/level/chunk/Chunk.java
index 2690c44eaae193a259fe195c95e59d07d5e1cc5a..3fdce0e6fa34eb4b1eafc618068a3fb06abd5ec1 100644
--- a/src/main/java/net/minecraft/world/level/chunk/Chunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/Chunk.java
@@ -465,7 +465,7 @@ public class Chunk implements IChunkAccess {
                 return null;
             }
 
-            chunksection = new ChunkSection(j >> 4 << 4);
+            chunksection = new ChunkSection(j >> 4 << 4, this, this.world, true); // Paper - Anti-Xray - Add parameters
             this.sections[j >> 4] = chunksection;
         }
 
diff --git a/src/main/java/net/minecraft/world/level/chunk/ChunkEmpty.java b/src/main/java/net/minecraft/world/level/chunk/ChunkEmpty.java
index 89efd0b68b04457e1cd617dcc8bb1a6ea1c4717c..9fb8d20e9e1a8cc716c32a100b1d70e90f385eca 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ChunkEmpty.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ChunkEmpty.java
@@ -8,6 +8,7 @@ import net.minecraft.SystemUtils;
 import net.minecraft.core.BlockPosition;
 import net.minecraft.core.IRegistry;
 import net.minecraft.data.worldgen.biome.BiomeRegistry;
+import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.level.PlayerChunk;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.level.ChunkCoordIntPair;
@@ -28,7 +29,7 @@ public class ChunkEmpty extends Chunk {
     });
 
     public ChunkEmpty(World world, ChunkCoordIntPair chunkcoordintpair) {
-        super(world, chunkcoordintpair, new BiomeStorage(world.r().b(IRegistry.ay), ChunkEmpty.b));
+        super(world, chunkcoordintpair, new BiomeStorage(MinecraftServer.getServer().getCustomRegistry().b(IRegistry.ay), ChunkEmpty.b)); // Paper - world isnt ready yet for anti xray use here, use server singleton for registry
     }
 
     // Paper start
diff --git a/src/main/java/net/minecraft/world/level/chunk/ChunkSection.java b/src/main/java/net/minecraft/world/level/chunk/ChunkSection.java
index eea4a30428293eaf7afbe303a37adec60b44c2b4..0b4e346daaea91565fde2f789fafa8b431a7b042 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ChunkSection.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ChunkSection.java
@@ -1,9 +1,11 @@
 package net.minecraft.world.level.chunk;
 
 import java.util.function.Predicate;
+import com.destroystokyo.paper.antixray.ChunkPacketInfo; // Paper - Anti-Xray - Add chunk packet info
 import javax.annotation.Nullable;
 import net.minecraft.nbt.GameProfileSerializer;
 import net.minecraft.network.PacketDataSerializer;
+import net.minecraft.world.level.World;
 import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.level.block.state.IBlockData;
@@ -18,16 +20,22 @@ public class ChunkSection {
     private short e;
     final DataPaletteBlock<IBlockData> blockIds; // Paper - package-private
 
-    public ChunkSection(int i) {
-        this(i, (short) 0, (short) 0, (short) 0);
+    // Paper start - Anti-Xray - Add parameters
+    @Deprecated public ChunkSection(int i) { this(i, null, null, true); } // Notice for updates: Please make sure this constructor isn't used anywhere
+    public ChunkSection(int i, IChunkAccess chunk, World world, boolean initializeBlocks) {
+        this(i, (short) 0, (short) 0, (short) 0, chunk, world, initializeBlocks);
+        // Paper end
     }
 
-    public ChunkSection(int i, short short0, short short1, short short2) {
+    // Paper start - Anti-Xray - Add parameters
+    @Deprecated public ChunkSection(int i, short short0, short short1, short short2) { this(i, short0, short1, short2, null, null, true); } // Notice for updates: Please make sure this constructor isn't used anywhere
+    public ChunkSection(int i, short short0, short short1, short short2, IChunkAccess chunk, World world, boolean initializeBlocks) {
+        // Paper end
         this.yPos = i;
         this.nonEmptyBlockCount = short0;
         this.tickingBlockCount = short1;
         this.e = short2;
-        this.blockIds = new DataPaletteBlock<>(ChunkSection.GLOBAL_PALETTE, Block.REGISTRY_ID, GameProfileSerializer::c, GameProfileSerializer::a, Blocks.AIR.getBlockData());
+        this.blockIds = new DataPaletteBlock<>(ChunkSection.GLOBAL_PALETTE, Block.REGISTRY_ID, GameProfileSerializer::c, GameProfileSerializer::a, Blocks.AIR.getBlockData(), world == null ? null : world.chunkPacketBlockController.getPredefinedBlockData(world, chunk, this, initializeBlocks), initializeBlocks); // Paper - Anti-Xray - Add predefined block data
     }
 
     public final IBlockData getType(int i, int j, int k) { // Paper
@@ -139,10 +147,14 @@ public class ChunkSection {
         return this.blockIds;
     }
 
-    public void writeChunkSection(PacketDataSerializer packetDataSerializer) { this.b(packetDataSerializer); } // Paper - OBFHELPER
-    public void b(PacketDataSerializer packetdataserializer) {
+    // Paper start - Anti-Xray - Add chunk packet info
+    @Deprecated public final void writeChunkSection(PacketDataSerializer packetDataSerializer) { this.b(packetDataSerializer); } // OBFHELPER // Notice for updates: Please make sure this method isn't used anywhere
+    @Deprecated public final void b(PacketDataSerializer packetdataserializer) { this.writeChunkSection(packetdataserializer, null); } // Notice for updates: Please make sure this method isn't used anywhere
+    public final void writeChunkSection(PacketDataSerializer packetDataSerializer, ChunkPacketInfo<IBlockData> chunkPacketInfo) { this.b(packetDataSerializer, chunkPacketInfo); } // OBFHELPER
+    public void b(PacketDataSerializer packetdataserializer, ChunkPacketInfo<IBlockData> chunkPacketInfo) {
+        // Paper end
         packetdataserializer.writeShort(this.nonEmptyBlockCount);
-        this.blockIds.b(packetdataserializer);
+        this.blockIds.writeDataPaletteBlock(packetdataserializer, chunkPacketInfo, this.yPos >> 4); // Paper - Anti-Xray - Add chunk packet info
     }
 
     public int j() {
diff --git a/src/main/java/net/minecraft/world/level/chunk/DataPaletteBlock.java b/src/main/java/net/minecraft/world/level/chunk/DataPaletteBlock.java
index cc0c5995dc3840ce66ea849849f7c37555d3b5e6..68d53a51acc9790b9cda20ec4d2ec6edd1baac1a 100644
--- a/src/main/java/net/minecraft/world/level/chunk/DataPaletteBlock.java
+++ b/src/main/java/net/minecraft/world/level/chunk/DataPaletteBlock.java
@@ -1,6 +1,7 @@
 package net.minecraft.world.level.chunk;
 
 import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
+import com.destroystokyo.paper.antixray.ChunkPacketInfo; // Paper - Anti-Xray - Add chunk packet info
 import java.util.Arrays;
 import java.util.Objects;
 import java.util.concurrent.locks.ReentrantLock;
@@ -27,6 +28,7 @@ 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; public final 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
@@ -51,14 +53,47 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
         //this.j.unlock(); // Paper - disable this
     }
 
-    public DataPaletteBlock(DataPalette<T> datapalette, RegistryBlockID<T> registryblockid, Function<NBTTagCompound, T> function, Function<T, NBTTagCompound> function1, T t0) {
+    // Paper start - Anti-Xray - Add predefined objects
+    @Deprecated public DataPaletteBlock(DataPalette<T> datapalette, RegistryBlockID<T> registryblockid, Function<NBTTagCompound, T> function, Function<T, NBTTagCompound> function1, T t0) { this(datapalette, registryblockid, function, function1, t0, null, true); } // Notice for updates: Please make sure this constructor isn't used anywhere
+    public DataPaletteBlock(DataPalette<T> datapalette, RegistryBlockID<T> registryblockid, Function<NBTTagCompound, T> function, Function<T, NBTTagCompound> function1, T t0, T[] predefinedObjects, boolean initialize) {
+        // Paper end
         this.b = datapalette;
         this.d = registryblockid;
         this.e = function;
         this.f = function1;
         this.g = t0;
-        this.b(4);
+        // Paper start - Anti-Xray - Add predefined objects
+        this.predefinedObjects = predefinedObjects;
+
+        if (initialize) {
+            if (predefinedObjects == null) {
+                // Default
+                this.initialize(4);
+            } else {
+                // MathHelper.d() is trailingBits(roundCeilPow2(n)), alternatively; (int)ceil(log2(n)); however it's trash, use numberOfLeadingZeros instead
+                // 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 = (32 - Integer.numberOfLeadingZeros(Math.max(16, maxIndex) - 1));
+
+                // Initialize with at least 15 free indixes
+                this.initialize((1 << bitCount) - predefinedObjects.length < 16 ? bitCount + 1 : bitCount);
+                this.addPredefinedObjects();
+            }
+        }
+        // Paper end
+    }
+
+    // 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
 
     private static int b(int i, int j, int k) {
         return j << 8 | k << 4 | i;
@@ -93,6 +128,7 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
 
         int j;
 
+        this.addPredefinedObjects(); // Paper - Anti-Xray - Add predefined objects
         for (j = 0; j < databits.b(); ++j) {
             T t1 = datapalette.a(databits.a(j));
 
@@ -142,24 +178,38 @@ public class DataPaletteBlock<T> implements DataPaletteExpandable<T> {
         return t0 == null ? this.g : t0;
     }
 
-    public void writeDataPaletteBlock(PacketDataSerializer packetDataSerializer) { this.b(packetDataSerializer); } // Paper - OBFHELPER
-    public synchronized void b(PacketDataSerializer packetdataserializer) { // Paper - synchronize
+    // Paper start - Anti-Xray - Add chunk packet info
+    @Deprecated public void writeDataPaletteBlock(PacketDataSerializer packetDataSerializer) { this.b(packetDataSerializer); } // OBFHELPER // Notice for updates: Please make sure this method isn't used anywhere
+    @Deprecated public void b(PacketDataSerializer packetdataserializer) { this.writeDataPaletteBlock(packetdataserializer, null, 0); } // Notice for updates: Please make sure this method isn't used anywhere
+    public void writeDataPaletteBlock(PacketDataSerializer packetDataSerializer, ChunkPacketInfo<T> chunkPacketInfo, int chunkSectionIndex) { this.b(packetDataSerializer, chunkPacketInfo, chunkSectionIndex); } // OBFHELPER
+    public synchronized void b(PacketDataSerializer packetdataserializer, ChunkPacketInfo<T> chunkPacketInfo, int chunkSectionIndex) { // Paper - synchronize
+        // Paper end
         this.a();
         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.b();
     }
 
     public synchronized void a(NBTTagList nbttaglist, long[] along) { // Paper - synchronize
         this.a();
-        int i = Math.max(4, MathHelper.e(nbttaglist.size()));
+        // 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 i = Math.max(4, MathHelper.e(nbttaglist.size() + (this.predefinedObjects == null ? 0 : this.predefinedObjects.length))); // Paper - Anti-Xray - Calculate the size with predefined objects
 
-        if (i != this.i) {
+        if (true || i != this.i) { // Paper - Anti-Xray - Not initialized yet
             this.b(i);
         }
 
         this.h.a(nbttaglist);
+        this.addPredefinedObjects(); // Paper - Anti-Xray - Add predefined objects
         int j = along.length * 64 / 4096;
 
         if (this.h == this.b) {
diff --git a/src/main/java/net/minecraft/world/level/chunk/ProtoChunk.java b/src/main/java/net/minecraft/world/level/chunk/ProtoChunk.java
index 9eeb99a21a6ed7f71ff64cf4cfdff646d31abbcf..9b308a10554b037ede0c455fbd3e906021218ddc 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ProtoChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ProtoChunk.java
@@ -64,16 +64,24 @@ public class ProtoChunk implements IChunkAccess {
     private long s;
     private final Map<WorldGenStage.Features, BitSet> t;
     private volatile boolean u;
+    private final World world; // Paper - Anti-Xray - Add world
 
-    public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter) {
+    // Paper start - Anti-Xray - Add world
+    @Deprecated public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter) { this(chunkcoordintpair, chunkconverter, null); } // Notice for updates: Please make sure this constructor isn't used anywhere
+    public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter, World world) {
+        // Paper end
         this(chunkcoordintpair, chunkconverter, (ChunkSection[]) null, new ProtoChunkTickList<>((block) -> {
             return block == null || block.getBlockData().isAir();
         }, chunkcoordintpair), new ProtoChunkTickList<>((fluidtype) -> {
             return fluidtype == null || fluidtype == FluidTypes.EMPTY;
-        }, chunkcoordintpair));
+        }, chunkcoordintpair), world); // Paper - Anti-Xray - Add world
     }
 
-    public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter, @Nullable ChunkSection[] achunksection, ProtoChunkTickList<Block> protochunkticklist, ProtoChunkTickList<FluidType> protochunkticklist1) {
+    // Paper start - Anti-Xray - Add world
+    @Deprecated public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter, @Nullable ChunkSection[] achunksection, ProtoChunkTickList<Block> protochunkticklist, ProtoChunkTickList<FluidType> protochunkticklist1) { this(chunkcoordintpair, chunkconverter, achunksection, protochunkticklist, protochunkticklist1, null); } // Notice for updates: Please make sure this constructor isn't used anywhere
+    public ProtoChunk(ChunkCoordIntPair chunkcoordintpair, ChunkConverter chunkconverter, @Nullable ChunkSection[] achunksection, ProtoChunkTickList<Block> protochunkticklist, ProtoChunkTickList<FluidType> protochunkticklist1, World world) {
+        this.world = world;
+        // Paper end
         this.f = Maps.newEnumMap(HeightMap.Type.class);
         this.g = ChunkStatus.EMPTY;
         this.h = Maps.newHashMap();
@@ -228,7 +236,7 @@ public class ProtoChunk implements IChunkAccess {
 
     public ChunkSection a(int i) {
         if (this.j[i] == Chunk.a) {
-            this.j[i] = new ChunkSection(i << 4);
+            this.j[i] = new ChunkSection(i << 4, this, this.world, true); // Paper - Anti-Xray - Add parameters
         }
 
         return this.j[i];
diff --git a/src/main/java/net/minecraft/world/level/chunk/ProtoChunkExtension.java b/src/main/java/net/minecraft/world/level/chunk/ProtoChunkExtension.java
index 9351e6ba541d440c485b6e4a3209170c5756e31e..7a82d43d51d80a3054e0871bf4b9aa7635920efc 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ProtoChunkExtension.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ProtoChunkExtension.java
@@ -27,7 +27,7 @@ public class ProtoChunkExtension extends ProtoChunk {
     private final Chunk a;
 
     public ProtoChunkExtension(Chunk chunk) {
-        super(chunk.getPos(), ChunkConverter.a);
+        super(chunk.getPos(), ChunkConverter.a, chunk.world); // Paper - Anti-Xray - Add parameter
         this.a = chunk;
     }
 
diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/ChunkRegionLoader.java b/src/main/java/net/minecraft/world/level/chunk/storage/ChunkRegionLoader.java
index 98bc26c7ae01884eb53766e72fc7cbabbf065e6e..c652897aae99c48c6cc020b5d64f6a8b02beecb5 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/ChunkRegionLoader.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/ChunkRegionLoader.java
@@ -101,7 +101,7 @@ public class ChunkRegionLoader {
             byte b0 = nbttagcompound2.getByte("Y");
 
             if (nbttagcompound2.hasKeyOfType("Palette", 9) && nbttagcompound2.hasKeyOfType("BlockStates", 12)) {
-                ChunkSection chunksection = new ChunkSection(b0 << 4);
+                ChunkSection chunksection = new ChunkSection(b0 << 4, null, worldserver, false); // Paper - Anti-Xray - Add parameters
 
                 chunksection.getBlocks().a(nbttagcompound2.getList("Palette", 10), nbttagcompound2.getLongArray("BlockStates"));
                 chunksection.recalcBlockCounts();
@@ -165,7 +165,7 @@ public class ChunkRegionLoader {
                 // CraftBukkit end
             });
         } else {
-            ProtoChunk protochunk = new ProtoChunk(chunkcoordintpair, chunkconverter, achunksection, protochunkticklist, protochunkticklist1);
+            ProtoChunk protochunk = new ProtoChunk(chunkcoordintpair, chunkconverter, achunksection, protochunkticklist, protochunkticklist1, worldserver); // Paper - Anti-Xray - Add parameter
 
             protochunk.a(biomestorage);
             object = protochunk;
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftChunk.java b/src/main/java/org/bukkit/craftbukkit/CraftChunk.java
index a8e94f69faec93661dc6ae2efeec44b8bfd2e965..c36f55f178166eb099cc5c64784be5a9f4750199 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftChunk.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftChunk.java
@@ -44,7 +44,7 @@ public class CraftChunk implements Chunk {
     private final WorldServer worldServer;
     private final int x;
     private final int z;
-    private static final DataPaletteBlock<IBlockData> emptyBlockIDs = new ChunkSection(0).getBlocks();
+    private static final DataPaletteBlock<IBlockData> emptyBlockIDs = new ChunkSection(0, null, null, true).getBlocks(); // Paper - Anti-Xray - Add parameters
     private static final byte[] emptyLight = new byte[2048];
 
     public CraftChunk(net.minecraft.world.level.chunk.Chunk chunk) {
@@ -288,7 +288,7 @@ public class CraftChunk implements Chunk {
                 NBTTagCompound data = new NBTTagCompound();
                 cs[i].getBlocks().a(data, "Palette", "BlockStates");
 
-                DataPaletteBlock blockids = new DataPaletteBlock<>(ChunkSection.GLOBAL_PALETTE, net.minecraft.world.level.block.Block.REGISTRY_ID, GameProfileSerializer::c, GameProfileSerializer::a, Blocks.AIR.getBlockData()); // TODO: snapshot whole ChunkSection
+                DataPaletteBlock blockids = new DataPaletteBlock<>(ChunkSection.GLOBAL_PALETTE, net.minecraft.world.level.block.Block.REGISTRY_ID, GameProfileSerializer::c, GameProfileSerializer::a, Blocks.AIR.getBlockData(), null, false); // TODO: snapshot whole ChunkSection // Paper - Anti-Xray - Add no predefined block data and don't initialize because it's done in the line below internally
                 blockids.a(data.getList("Palette", CraftMagicNumbers.NBT.TAG_COMPOUND), data.getLongArray("BlockStates"));
 
                 sectionBlockIDs[i] = blockids;
diff --git a/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java b/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java
index 3d15915275331cb767750c24c89b4b43d43033ef..afca0038bb74ac53f07a25729a3c1542e244c6fd 100644
--- a/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java
+++ b/src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java
@@ -21,9 +21,11 @@ public final class CraftChunkData implements ChunkGenerator.ChunkData {
     private final int maxHeight;
     private final ChunkSection[] sections;
     private Set<BlockPosition> tiles;
+    private World world; // Paper - Anti-Xray - Add world
 
     public CraftChunkData(World world) {
         this(world.getMaxHeight());
+        this.world = world; // Paper - Anti-Xray - Add world
     }
 
     /* pp for tests */ CraftChunkData(int maxHeight) {
@@ -157,7 +159,7 @@ 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 >> 4 << 4);
+            sections[y >> 4] = section = new ChunkSection(y >> 4 << 4, null, world instanceof org.bukkit.craftbukkit.CraftWorld ? ((org.bukkit.craftbukkit.CraftWorld) world).getHandle() : null, true); // Paper - Anti-Xray - Add parameters
         }
         return section;
     }