From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zach Brown <zach@zachbr.io>
Date: Tue, 23 Jul 2019 20:44:47 -0500
Subject: [PATCH] Do not let the server load chunks from newer versions

If the server attempts to load a chunk generated by a newer version of
the game, immediately stop the server to prevent data corruption.

You can override this functionality at your own peril.

diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/SerializableChunkData.java b/src/main/java/net/minecraft/world/level/chunk/storage/SerializableChunkData.java
index 92ad7704a77c024afe090488764eaf59a4f7505f..d7a204216332ccbd6bece23bd507be0366ea4d61 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/SerializableChunkData.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/SerializableChunkData.java
@@ -104,11 +104,25 @@ public record SerializableChunkData(Registry<Biome> biomeRegistry, ChunkPos chun
     }
     // Paper end - guard against serializing mismatching coordinates
 
+    // Paper start - Do not let the server load chunks from newer versions
+    private static final int CURRENT_DATA_VERSION = net.minecraft.SharedConstants.getCurrentVersion().getDataVersion().getVersion();
+    private static final boolean JUST_CORRUPT_IT = Boolean.getBoolean("Paper.ignoreWorldDataVersion");
+    // Paper end - Do not let the server load chunks from newer versions
+
     @Nullable
     public static SerializableChunkData parse(LevelHeightAccessor world, RegistryAccess registryManager, CompoundTag nbt) {
         if (!nbt.contains("Status", 8)) {
             return null;
         } else {
+            // Paper start - Do not let the server load chunks from newer versions
+            if (nbt.contains("DataVersion", net.minecraft.nbt.Tag.TAG_ANY_NUMERIC)) {
+                final int dataVersion = nbt.getInt("DataVersion");
+                if (!JUST_CORRUPT_IT && dataVersion > CURRENT_DATA_VERSION) {
+                    new RuntimeException("Server attempted to load chunk saved with newer version of minecraft! " + dataVersion + " > " + CURRENT_DATA_VERSION).printStackTrace();
+                    System.exit(1);
+                }
+            }
+            // Paper end - Do not let the server load chunks from newer versions
             ChunkPos chunkcoordintpair = new ChunkPos(nbt.getInt("xPos"), nbt.getInt("zPos")); // Paper - guard against serializing mismatching coordinates; diff on change, see ChunkSerializer#getChunkCoordinate
             long i = nbt.getLong("LastUpdate");
             long j = nbt.getLong("InhabitedTime");