Warn on plugins accessing faraway chunks (#8208)

patches/server/0007-MC-Utils.patch

@@ -3009,6 +3009,36 @@ index 0000000000000000000000000000000000000000..cea9c098ade00ee87b8efc8164ab72f5
 +        return this.sum;
 +    }
 +}
+diff --git a/src/main/java/io/papermc/paper/util/StackWalkerUtil.java b/src/main/java/io/papermc/paper/util/StackWalkerUtil.java
+new file mode 100644
+index 0000000000000000000000000000000000000000..f7114d5b8f2f93f62883e24da29afaf9f74ee1a6
+--- /dev/null
++++ b/src/main/java/io/papermc/paper/util/StackWalkerUtil.java
+@@ -0,0 +1,24 @@
++package io.papermc.paper.util;
++
++import org.bukkit.plugin.java.JavaPlugin;
++import org.bukkit.plugin.java.PluginClassLoader;
++import org.jetbrains.annotations.Nullable;
++
++import java.util.Optional;
++
++public class StackWalkerUtil {
++
++    @Nullable
++    public static JavaPlugin getFirstPluginCaller() {
++        Optional<JavaPlugin> foundFrame = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE)
++            .walk(stream -> stream
++                .filter(frame -> frame.getDeclaringClass().getClassLoader() instanceof PluginClassLoader)
++                .map((frame) -> {
++                    PluginClassLoader classLoader = (PluginClassLoader) frame.getDeclaringClass().getClassLoader();
++                    return classLoader.getPlugin();
++                })
++                .findFirst());
++
++        return foundFrame.orElse(null);
++    }
++}
 diff --git a/src/main/java/io/papermc/paper/util/WorldUtil.java b/src/main/java/io/papermc/paper/util/WorldUtil.java
 new file mode 100644
 index 0000000000000000000000000000000000000000..67bb91fcfb532a919954cd9d7733d09a6c3fec35

patches/server/0926-Warn-on-plugins-accessing-faraway-chunks.patch

@@ -0,0 +1,96 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Owen1212055 <23108066+Owen1212055@users.noreply.github.com>
+Date: Fri, 29 Jul 2022 12:35:19 -0400
+Subject: [PATCH] Warn on plugins accessing faraway chunks
+
+
+diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
+index 9467ccaa1d73e1913495a46919aee530e749977d..5a2a1d394852d39ea576624586f7fa736dec807c 100644
+--- a/src/main/java/net/minecraft/world/level/Level.java
++++ b/src/main/java/net/minecraft/world/level/Level.java
+@@ -418,7 +418,7 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
+     }
+ 
+     private static boolean isInWorldBoundsHorizontal(BlockPos pos) {
+-        return pos.getX() >= -30000000 && pos.getZ() >= -30000000 && pos.getX() < 30000000 && pos.getZ() < 30000000;
++        return pos.getX() >= -30000000 && pos.getZ() >= -30000000 && pos.getX() < 30000000 && pos.getZ() < 30000000; // Dif on change
+     }
+ 
+     private static boolean isOutsideSpawnableHeight(int y) {
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+index a5d8dfc77475845be7c6d37eed04fb19eeef1c0c..f0b14914438840bd819fa7da8b76f4fcc13704d0 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+@@ -314,9 +314,24 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+     public boolean setSpawnLocation(int x, int y, int z) {
+         return this.setSpawnLocation(x, y, z, 0.0F);
+     }
++    // Paper start
++    private static void warnUnsafeChunk(String reason, int x, int z) {
++        // if any chunk coord is outside of 30 million blocks
++        if (x > 1875000 || z > 1875000 || x < -1875000 || z < -1875000) {
++            Plugin plugin = io.papermc.paper.util.StackWalkerUtil.getFirstPluginCaller();
++            if (plugin != null) {
++                plugin.getLogger().warning("Plugin is %s at (%s, %s), this might cause issues.".formatted(reason, x, z));
++            }
++            if (net.minecraft.server.MinecraftServer.getServer().isDebugging()) {
++                io.papermc.paper.util.TraceUtil.dumpTraceForThread("Dangerous chunk retrieval");
++            }
++        }
++    }
++    // Paper end
+ 
+     @Override
+     public Chunk getChunkAt(int x, int z) {
++        warnUnsafeChunk("getting a faraway chunk", x, z); // Paper
+         // Paper start - add ticket to hold chunk for a little while longer if plugin accesses it
+         net.minecraft.world.level.chunk.LevelChunk chunk = world.getChunkSource().getChunkAtIfLoadedImmediately(x, z);
+         if (chunk == null) {
+@@ -432,6 +447,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+     @Override
+     public boolean regenerateChunk(int x, int z) {
+         org.spigotmc.AsyncCatcher.catchOp("chunk regenerate"); // Spigot
++        warnUnsafeChunk("regenerating a faraway chunk", x, z); // Paper
+         // Paper start - implement regenerateChunk method
+         final ServerLevel serverLevel = this.world;
+         final net.minecraft.server.level.ServerChunkCache serverChunkCache = serverLevel.getChunkSource();
+@@ -525,6 +541,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+     @Override
+     public boolean loadChunk(int x, int z, boolean generate) {
+         org.spigotmc.AsyncCatcher.catchOp("chunk load"); // Spigot
++        warnUnsafeChunk("loading a faraway chunk", x, z); // Paper
+         // Paper start - Optimize this method
+         ChunkPos chunkPos = new ChunkPos(x, z);
+         ChunkAccess immediate = world.getChunkSource().getChunkAtIfLoadedImmediately(x, z); // Paper
+@@ -589,6 +606,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+ 
+     @Override
+     public boolean addPluginChunkTicket(int x, int z, Plugin plugin) {
++        warnUnsafeChunk("adding a faraway chunk ticket", x, z); // Paper
+         Preconditions.checkArgument(plugin != null, "null plugin");
+         Preconditions.checkArgument(plugin.isEnabled(), "plugin is not enabled");
+ 
+@@ -670,6 +688,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+ 
+     @Override
+     public void setChunkForceLoaded(int x, int z, boolean forced) {
++        warnUnsafeChunk("forceloading a faraway chunk", x, z); // Paper
+         this.getHandle().setChunkForced(x, z, forced);
+     }
+ 
+@@ -981,6 +1000,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+ 
+     @Override
+     public int getHighestBlockYAt(int x, int z, org.bukkit.HeightMap heightMap) {
++        warnUnsafeChunk("getting a faraway chunk", x >> 4, z >> 4); // Paper
+         // Transient load for this tick
+         return this.world.getChunk(x >> 4, z >> 4).getHeight(CraftHeightMap.toNMS(heightMap), x, z);
+     }
+@@ -2238,6 +2258,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+     // Paper start
+     @Override
+     public java.util.concurrent.CompletableFuture<Chunk> getChunkAtAsync(int x, int z, boolean gen, boolean urgent) {
++        warnUnsafeChunk("getting a faraway chunk async", x, z); // Paper
+         if (Bukkit.isPrimaryThread()) {
+             net.minecraft.world.level.chunk.LevelChunk immediate = this.world.getChunkSource().getChunkAtIfLoadedImmediately(x, z);
+             if (immediate != null) {