From 868bf96eda2b222fbf07a80be163ca2bc3e60a4f Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Fri, 15 Feb 2019 01:08:19 -0500
Subject: [PATCH] Allow Saving of Oversized Chunks

The Minecraft World Region File format has a hard cap of 1MB per chunk.
This is due to the fact that the header of the file format only allocates
a single byte for sector count, meaning a maximum of 256 sectors, at 4k per sector.

This limit can be reached fairly easily with books, resulting in the chunk being unable
to save to the world. Worse off, is that nothing printed when this occured, and silently
performed a chunk rollback on next load.

This leads to security risk with duplication and is being actively exploited.

This patch catches the too large scenario, falls back and moves any large Entity
or Tile Entity into a new compound, and this compound is saved into a different file.

On Chunk Load, we check for oversized status, and if so, we load the extra file and
merge the Entities and Tile Entities from the oversized chunk back into the level to
then be loaded as normal.

Once a chunk is returned back to normal size, the oversized flag will clear, and no
extra data file will exist.

This fix maintains compatability with all existing Anvil Region Format tools as it
does not alter the save format. They will just not know about the extra entities.

This fix also maintains compatability if someone switches server jars to one without
this fix, as the data will remain in the oversized file. Once the server returns
to a jar with this fix, the data will be restored.

diff --git a/src/main/java/net/minecraft/server/NBTCompressedStreamTools.java b/src/main/java/net/minecraft/server/NBTCompressedStreamTools.java
index 9fd8a75dae..d49afd622e 100644
--- a/src/main/java/net/minecraft/server/NBTCompressedStreamTools.java
+++ b/src/main/java/net/minecraft/server/NBTCompressedStreamTools.java
@@ -69,6 +69,7 @@ public class NBTCompressedStreamTools {
 
     }
 
+    public static NBTTagCompound readNBT(DataInputStream datainputstream) throws IOException { return a(datainputstream); } // Paper - OBFHELPER
     public static NBTTagCompound a(DataInputStream datainputstream) throws IOException {
         return a((DataInput) datainputstream, NBTReadLimiter.a);
     }
@@ -89,6 +90,7 @@ public class NBTCompressedStreamTools {
         }
     }
 
+    public static void writeNBT(NBTTagCompound nbttagcompound, DataOutput dataoutput) throws IOException { a(nbttagcompound, dataoutput); } // Paper - OBFHELPER
     public static void a(NBTTagCompound nbttagcompound, DataOutput dataoutput) throws IOException {
         a((NBTBase) nbttagcompound, dataoutput);
     }
diff --git a/src/main/java/net/minecraft/server/NBTTagList.java b/src/main/java/net/minecraft/server/NBTTagList.java
index b7c94fe238..80eea5dfbd 100644
--- a/src/main/java/net/minecraft/server/NBTTagList.java
+++ b/src/main/java/net/minecraft/server/NBTTagList.java
@@ -11,7 +11,7 @@ import java.util.Objects;
 
 public class NBTTagList extends NBTList<NBTBase> {
 
-    private List<NBTBase> list = Lists.newArrayList();
+    List<NBTBase> list = Lists.newArrayList(); // Paper - private -> package
     private byte type = 0;
 
     public NBTTagList() {}
diff --git a/src/main/java/net/minecraft/server/RegionFile.java b/src/main/java/net/minecraft/server/RegionFile.java
index e68f901943..ed2ccebb23 100644
--- a/src/main/java/net/minecraft/server/RegionFile.java
+++ b/src/main/java/net/minecraft/server/RegionFile.java
@@ -23,7 +23,7 @@ public class RegionFile implements AutoCloseable {
     // Minecraft is limited to 256 sections per chunk. So 1MB. This can easily be overriden.
     // So we extend this to use the REAL size when the count is maxed by seeking to that section and reading the length.
     private static final boolean ENABLE_EXTENDED_SAVE = Boolean.parseBoolean(System.getProperty("net.minecraft.server.RegionFile.enableExtendedSave", "true"));
-    private final File file;
+    final File file; // Paper - private -> package
     // Spigot end
     private static final byte[] a = new byte[4096];
     private final RandomAccessFile b; private RandomAccessFile getDataFile() { return this.b; } // Paper - OBFHELPER
@@ -33,6 +33,7 @@ public class RegionFile implements AutoCloseable {
 
     public RegionFile(File file) throws IOException {
         this.b = new RandomAccessFile(file, "rw");
+        this.file = file; // Spigot // Paper - We need this earlier
         if (this.b.length() < 8192L) { // Paper - headers should be 8192
             this.b.write(RegionFile.a);
             this.b.write(RegionFile.a);
@@ -66,6 +67,7 @@ public class RegionFile implements AutoCloseable {
         }
         header.clear();
         java.nio.IntBuffer headerAsInts = header.asIntBuffer();
+        initOversizedState();
         // Paper End
 
         int k;
@@ -83,7 +85,7 @@ public class RegionFile implements AutoCloseable {
                     this.b.seek(j * 4 + 4); // Go back to where we were
                 }
             }
-            if (k > 0 && (k >> 8) > 1 && (k >> 8) + (k & 255) <= this.e.size()) { // Paper >= 1 as 0/1 are the headers, and negative isnt valid
+            if (k > 0 && (k >> 8) > 1 && (k >> 8) + (length) <= this.e.size()) { // Paper >= 1 as 0/1 are the headers, and negative isnt valid
                 for (int l = 0; l < (length); ++l) {
                     // Spigot end
                     this.e.set((k >> 8) + l, false);
@@ -102,11 +104,11 @@ public class RegionFile implements AutoCloseable {
             if (offsets[j] != 0) this.timestamps[j] = k; // Paper - don't set timestamp if it got 0'd above due to corruption
         }
 
-        this.file = file; // Spigot
+        // Paper - we need this earlier
     }
 
     @Nullable
-    public synchronized DataInputStream a(ChunkCoordIntPair chunkcoordintpair) {
+    public synchronized DataInputStream getReadStream(ChunkCoordIntPair chunkcoordintpair) { return this.a(chunkcoordintpair); } public synchronized DataInputStream a(ChunkCoordIntPair chunkcoordintpair) { // Paper - OBFHELPER
         try {
             int i = this.getOffset(chunkcoordintpair);
 
@@ -182,8 +184,8 @@ public class RegionFile implements AutoCloseable {
         }
     }
 
-    public DataOutputStream c(ChunkCoordIntPair chunkcoordintpair) {
-        return new DataOutputStream(new BufferedOutputStream(new DeflaterOutputStream(new RegionFile.ChunkBuffer(chunkcoordintpair))));
+    public DataOutputStream getWriteStream(ChunkCoordIntPair chunkcoordintpair) { return this.c(chunkcoordintpair); } public DataOutputStream c(ChunkCoordIntPair chunkcoordintpair) { // Paper - OBFHELPER
+        return new DataOutputStream(new RegionFile.ChunkBuffer(chunkcoordintpair)); // Paper - remove middleware, move deflate to .close() for dynamic levels
     }
 
     protected synchronized void a(ChunkCoordIntPair chunkcoordintpair, byte[] abyte, int i) {
@@ -201,8 +203,9 @@ public class RegionFile implements AutoCloseable {
 
             if (i1 >= 256) {
                 // Spigot start
-                if (!ENABLE_EXTENDED_SAVE) throw new RuntimeException(String.format("Too big to save, %d > 1048576", i));
+                if (!USE_SPIGOT_OVERSIZED_METHOD && !RegionFileCache.isOverzealous()) throw new ChunkTooLargeException(chunkcoordintpair.x, chunkcoordintpair.z, l); // Paper - throw error instead
                 org.bukkit.Bukkit.getLogger().log(java.util.logging.Level.WARNING,"Large Chunk Detected: ({0}) Size: {1} {2}", new Object[]{chunkcoordintpair, i1, this.file});
+                if (!ENABLE_EXTENDED_SAVE) throw new RuntimeException(String.format("Too big to save, %d > 1048576", i)); // Paper - move after our check
                 // Spigot end
             }
 
@@ -352,6 +355,109 @@ public class RegionFile implements AutoCloseable {
             logger.error("Error backing up corrupt file" + file.getAbsolutePath(), e);
         }
     }
+
+    private final byte[] oversized = new byte[1024];
+    private int oversizedCount = 0;
+
+    private synchronized void initOversizedState() throws IOException {
+        File metaFile = getOversizedMetaFile();
+        if (metaFile.exists()) {
+            final byte[] read = java.nio.file.Files.readAllBytes(metaFile.toPath());
+            System.arraycopy(read, 0, oversized, 0, oversized.length);
+            for (byte temp : oversized) {
+                oversizedCount += temp;
+            }
+        }
+    }
+
+    private static int getChunkIndex(int x, int z) {
+        return (x & 31) + (z & 31) * 32;
+    }
+    synchronized boolean isOversized(int x, int z) {
+        return this.oversized[getChunkIndex(x, z)] == 1;
+    }
+    synchronized void setOversized(int x, int z, boolean oversized) throws IOException {
+        final int offset = getChunkIndex(x, z);
+        boolean previous = this.oversized[offset] == 1;
+        this.oversized[offset] = (byte) (oversized ? 1 : 0);
+        if (!previous && oversized) {
+            oversizedCount++;
+        } else if (!oversized && previous) {
+            oversizedCount--;
+        }
+        if (previous && !oversized) {
+            File oversizedFile = getOversizedFile(x, z);
+            if (oversizedFile.exists()) {
+                oversizedFile.delete();
+            }
+        }
+        if (oversizedCount > 0) {
+            if (previous != oversized) {
+                writeOversizedMeta();
+            }
+        } else if (previous) {
+            File oversizedMetaFile = getOversizedMetaFile();
+            if (oversizedMetaFile.exists()) {
+                oversizedMetaFile.delete();
+            }
+        }
+    }
+
+    private void writeOversizedMeta() throws IOException {
+        java.nio.file.Files.write(getOversizedMetaFile().toPath(), oversized);
+    }
+
+    private File getOversizedMetaFile() {
+        return new File(this.file.getParentFile(), this.file.getName().replaceAll("\\.mca$", "") + ".oversized.nbt");
+    }
+
+    private File getOversizedFile(int x, int z) {
+        return new File(this.file.getParentFile(), this.file.getName().replaceAll("\\.mca$", "") + "_oversized_" + x + "_" + z + ".nbt");
+    }
+
+    void writeOversizedData(int x, int z, NBTTagCompound oversizedData) throws IOException {
+        File file = getOversizedFile(x, z);
+        try (DataOutputStream out = new DataOutputStream(new BufferedOutputStream(new DeflaterOutputStream(new java.io.FileOutputStream(file), new java.util.zip.Deflater(java.util.zip.Deflater.BEST_COMPRESSION), 32 * 1024), 32 * 1024))) {
+            NBTCompressedStreamTools.writeNBT(oversizedData, out);
+        }
+        this.setOversized(x, z, true);
+
+    }
+
+    synchronized NBTTagCompound getOversizedData(int x, int z) throws IOException {
+        File file = getOversizedFile(x, z);
+        try (DataInputStream out = new DataInputStream(new BufferedInputStream(new InflaterInputStream(new java.io.FileInputStream(file))))) {
+            return NBTCompressedStreamTools.readNBT(out);
+        }
+
+    }
+
+    private static final boolean USE_SPIGOT_OVERSIZED_METHOD = Boolean.getBoolean("Paper.useSpigotExtendedSaveMethod"); // Paper
+    static {
+        if (USE_SPIGOT_OVERSIZED_METHOD) {
+            org.bukkit.Bukkit.getLogger().log(java.util.logging.Level.SEVERE, "====================================");
+            org.bukkit.Bukkit.getLogger().log(java.util.logging.Level.SEVERE, "Using Spigot Oversized Chunk save method. Warning this will result in extremely fragmented chunks, as well as making the entire region file unable to be to used in any other software but Forge or Spigot (not usable in Vanilla or CraftBukkit). Paper's method is highly recommended.");
+            org.bukkit.Bukkit.getLogger().log(java.util.logging.Level.SEVERE, "====================================");
+        }
+    }
+    public class ChunkTooLargeException extends RuntimeException {
+        public ChunkTooLargeException(int x, int z, int sectors) {
+            super("Chunk " + x + "," + z + " of " + RegionFile.this.file.toString() + " is too large (" + sectors + "/255)");
+        }
+    }
+    private static class DirectByteArrayOutputStream extends ByteArrayOutputStream {
+        public DirectByteArrayOutputStream() {
+            super();
+        }
+
+        public DirectByteArrayOutputStream(int size) {
+            super(size);
+        }
+
+        public byte[] getBuffer() {
+            return this.buf;
+        }
+    }
     // Paper end
 
     class ChunkBuffer extends ByteArrayOutputStream {
@@ -363,8 +469,35 @@ public class RegionFile implements AutoCloseable {
             this.b = chunkcoordintpair;
         }
 
-        public void close() {
-            RegionFile.this.a(this.b, this.buf, this.count);
+        public void close() throws IOException {
+            // Paper start - apply dynamic compression
+            int origLength = this.count;
+            byte[] buf = this.buf;
+            DirectByteArrayOutputStream out = compressData(buf, origLength);
+            byte[] bytes = out.getBuffer();
+            int length = out.size();
+
+            RegionFile.this.a(this.b, bytes, length); // Paper - change to bytes/length
         }
     }
+
+    private static final byte[] compressionBuffer = new byte[1024 * 64]; // 64k fits most standard chunks input size even, ideally 1 pass through zlib
+    private static final java.util.zip.Deflater deflater = new java.util.zip.Deflater();
+    // since file IO is single threaded, no benefit to using per-region file buffers/synchronization, we can change that later if it becomes viable.
+    private static DirectByteArrayOutputStream compressData(byte[] buf, int length) throws IOException {
+        synchronized (deflater) {
+            deflater.setInput(buf, 0, length);
+            deflater.finish();
+
+            DirectByteArrayOutputStream out = new DirectByteArrayOutputStream(length);
+            while (!deflater.finished()) {
+                out.write(compressionBuffer, 0, deflater.deflate(compressionBuffer));
+            }
+            out.close();
+            deflater.reset();
+            return out;
+        }
+    }
+    // Paper end
+
 }
diff --git a/src/main/java/net/minecraft/server/RegionFileCache.java b/src/main/java/net/minecraft/server/RegionFileCache.java
index 8718811655..c53518a477 100644
--- a/src/main/java/net/minecraft/server/RegionFileCache.java
+++ b/src/main/java/net/minecraft/server/RegionFileCache.java
@@ -47,6 +47,7 @@ public abstract class RegionFileCache implements AutoCloseable {
         // Paper start
     }
 
+    public RegionFile getRegionFile(ChunkCoordIntPair chunkcoordintpair, boolean existingOnly) throws IOException { return this.a(chunkcoordintpair, existingOnly); } // Paper - OBFHELPER
     private RegionFile a(ChunkCoordIntPair chunkcoordintpair, boolean existingOnly) throws IOException { // CraftBukkit
         long i = ChunkCoordIntPair.pair(chunkcoordintpair.getRegionX(), chunkcoordintpair.getRegionZ());
         RegionFile regionfile = (RegionFile) this.cache.getAndMoveToFirst(i);
@@ -79,12 +80,151 @@ public abstract class RegionFileCache implements AutoCloseable {
     public synchronized boolean hasRegionFile(File file, int i, int j) {
         return cache.containsKey(ChunkCoordIntPair.pair(i, j));
     }
+    // Paper start
+    private static void printOversizedLog(String msg, File file, int x, int z) {
+        org.apache.logging.log4j.LogManager.getLogger().fatal(msg + " (" + file.toString().replaceAll(".+[\\\\/]", "") + " - " + x + "," + z + ") Go clean it up to remove this message. /minecraft:tp " + (x<<4)+" 128 "+(z<<4) + " - DO NOT REPORT THIS TO PAPER - You may ask for help on Discord, but do not file an issue. These error messages can not be removed.");
+    }
+
+    private static final int DEFAULT_SIZE_THRESHOLD = 1024 * 8;
+    private static final int OVERZEALOUS_TOTAL_THRESHOLD = 1024 * 64;
+    private static final int OVERZEALOUS_THRESHOLD = 1024;
+    private static int SIZE_THRESHOLD = DEFAULT_SIZE_THRESHOLD;
+    private static void resetFilterThresholds() {
+        SIZE_THRESHOLD = Math.max(1024 * 4, Integer.getInteger("Paper.FilterThreshhold", DEFAULT_SIZE_THRESHOLD));
+    }
+    static {
+        resetFilterThresholds();
+    }
+
+    static boolean isOverzealous() {
+        return SIZE_THRESHOLD == OVERZEALOUS_THRESHOLD;
+    }
+
+    private void writeRegion(ChunkCoordIntPair chunk, NBTTagCompound nbttagcompound) throws IOException {
+        RegionFile regionfile = getRegionFile(chunk, false);
+
+        int chunkX = chunk.x;
+        int chunkZ = chunk.z;
+
+        DataOutputStream out = regionfile.getWriteStream(chunk);
+        try {
+            NBTCompressedStreamTools.writeNBT(nbttagcompound, out);
+            out.close();
+            regionfile.setOversized(chunkX, chunkZ, false);
+        } catch (RegionFile.ChunkTooLargeException ignored) {
+            printOversizedLog("ChunkTooLarge! Someone is trying to duplicate.", regionfile.file, chunkX, chunkZ);
+            // Clone as we are now modifying it, don't want to corrupt the pending save state
+            nbttagcompound = nbttagcompound.clone();
+            // Filter out TileEntities and Entities
+            NBTTagCompound oversizedData = filterChunkData(nbttagcompound);
+            //noinspection SynchronizationOnLocalVariableOrMethodParameter
+            synchronized (regionfile) {
+                out = regionfile.getWriteStream(chunk);
+                NBTCompressedStreamTools.writeNBT(nbttagcompound, out);
+                try {
+                    out.close();
+                    // 2048 is below the min allowed, so it means we enter overzealous mode below
+                    if (SIZE_THRESHOLD == OVERZEALOUS_THRESHOLD) {
+                        resetFilterThresholds();
+                    }
+                } catch (RegionFile.ChunkTooLargeException e) {
+                    printOversizedLog("ChunkTooLarge even after reduction. Trying in overzealous mode.", regionfile.file, chunkX, chunkZ);
+                    // Eek, major fail. We have retry logic, so reduce threshholds and fall back
+                    SIZE_THRESHOLD = OVERZEALOUS_THRESHOLD;
+                    throw e;
+                }
+
+                regionfile.writeOversizedData(chunkX, chunkZ, oversizedData);
+            }
+        }
+    }
+
+    private static NBTTagCompound filterChunkData(NBTTagCompound chunk) {
+        NBTTagCompound oversizedLevel = new NBTTagCompound();
+        NBTTagCompound level = chunk.getCompound("Level");
+        filterChunkList(level, oversizedLevel, "Entities");
+        filterChunkList(level, oversizedLevel, "TileEntities");
+        NBTTagCompound oversized = new NBTTagCompound();
+        oversized.set("Level", oversizedLevel);
+        return oversized;
+    }
+
+    private static void filterChunkList(NBTTagCompound level, NBTTagCompound extra, String key) {
+        NBTTagList list = level.getList(key, 10);
+        NBTTagList newList = extra.getList(key, 10);
+        int totalSize = 0;
+        for (java.util.Iterator<NBTBase> iterator = list.list.iterator(); iterator.hasNext();) {
+            NBTBase object = iterator.next();
+            int nbtSize = getNBTSize(object);
+            if (nbtSize > SIZE_THRESHOLD || (SIZE_THRESHOLD == OVERZEALOUS_THRESHOLD && totalSize > OVERZEALOUS_TOTAL_THRESHOLD)) {
+                newList.add(object);
+                iterator.remove();
+            } else  {
+                totalSize += nbtSize;
+            }
+        }
+        level.set(key, list);
+        extra.set(key, newList);
+    }
+
+
+    private static NBTTagCompound readOversizedChunk(RegionFile regionfile, ChunkCoordIntPair chunkCoordinate) throws IOException {
+        synchronized (regionfile) {
+            try (DataInputStream datainputstream = regionfile.getReadStream(chunkCoordinate)) {
+                NBTTagCompound oversizedData = regionfile.getOversizedData(chunkCoordinate.x, chunkCoordinate.z);
+                NBTTagCompound chunk = NBTCompressedStreamTools.readNBT(datainputstream);
+                if (oversizedData == null) {
+                    return chunk;
+                }
+                NBTTagCompound oversizedLevel = oversizedData.getCompound("Level");
+                NBTTagCompound level = chunk.getCompound("Level");
+
+                mergeChunkList(level, oversizedLevel, "Entities");
+                mergeChunkList(level, oversizedLevel, "TileEntities");
+
+                chunk.set("Level", level);
+
+                return chunk;
+            } catch (Throwable throwable) {
+                throwable.printStackTrace();
+                throw throwable;
+            }
+        }
+    }
+
+    private static void mergeChunkList(NBTTagCompound level, NBTTagCompound oversizedLevel, String key) {
+        NBTTagList levelList = level.getList(key, 10);
+        NBTTagList oversizedList = oversizedLevel.getList(key, 10);
+
+        if (!oversizedList.isEmpty()) {
+            levelList.addAll(oversizedList);
+            level.set(key, levelList);
+        }
+    }
+
+    private static int getNBTSize(NBTBase nbtBase) {
+        DataOutputStream test = new DataOutputStream(new org.apache.commons.io.output.NullOutputStream());
+        try {
+            nbtBase.write(test);
+            return test.size();
+        } catch (IOException e) {
+            e.printStackTrace();
+            return 0;
+        }
+    }
+
     // Paper End
 
     @Nullable
     public NBTTagCompound read(ChunkCoordIntPair chunkcoordintpair) throws IOException {
         RegionFile regionfile = this.a(chunkcoordintpair, false); // CraftBukkit
         DataInputStream datainputstream = regionfile.a(chunkcoordintpair);
+        // Paper start
+        if (regionfile.isOversized(chunkcoordintpair.x, chunkcoordintpair.z)) {
+            printOversizedLog("Loading Oversized Chunk!", regionfile.file, chunkcoordintpair.x, chunkcoordintpair.z);
+            return readOversizedChunk(regionfile, chunkcoordintpair);
+        }
+        // Paper end
         Throwable throwable = null;
 
         NBTTagCompound nbttagcompound;
@@ -119,29 +259,32 @@ public abstract class RegionFileCache implements AutoCloseable {
 
     protected void write(ChunkCoordIntPair chunkcoordintpair, NBTTagCompound nbttagcompound) throws IOException {
         int attempts = 0; Exception laste = null; while (attempts++ < 5) { try { // Paper
-        RegionFile regionfile = this.a(chunkcoordintpair, false); // CraftBukkit
-        DataOutputStream dataoutputstream = regionfile.c(chunkcoordintpair);
-        Throwable throwable = null;
-
-        try {
-            NBTCompressedStreamTools.a(nbttagcompound, (DataOutput) dataoutputstream);
-        } catch (Throwable throwable1) {
-            throwable = throwable1;
-            throw throwable1;
-        } finally {
-            if (dataoutputstream != null) {
-                if (throwable != null) {
-                    try {
-                        dataoutputstream.close();
-                    } catch (Throwable throwable2) {
-                        throwable.addSuppressed(throwable2);
-                    }
-                } else {
-                    dataoutputstream.close();
-                }
-            }
-
-        }
+        // Paper start
+        this.writeRegion(chunkcoordintpair, nbttagcompound);
+//        RegionFile regionfile = this.a(chunkcoordintpair, false); // CraftBukkit
+//        DataOutputStream dataoutputstream = regionfile.c(chunkcoordintpair);
+//        Throwable throwable = null;
+//
+//        try {
+//            NBTCompressedStreamTools.a(nbttagcompound, (DataOutput) dataoutputstream);
+//        } catch (Throwable throwable1) {
+//            throwable = throwable1;
+//            throw throwable1;
+//        } finally {
+//            if (dataoutputstream != null) {
+//                if (throwable != null) {
+//                    try {
+//                        dataoutputstream.close();
+//                    } catch (Throwable throwable2) {
+//                        throwable.addSuppressed(throwable2);
+//                    }
+//                } else {
+//                    dataoutputstream.close();
+//                }
+//            }
+//
+//        }
+        // Paper end
 
             // Paper start
             return;
-- 
2.21.0

