From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Sat, 12 Dec 2020 23:45:28 +0000
Subject: [PATCH] Limit recipe packets


diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
index c14df29b190a9c0126545e0084b6283efc3ce7b0..152857012d46e05c185e2a3f62a770419f2dcbc6 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -326,6 +326,13 @@ public class PaperConfig {
         tabSpamLimit = getInt("settings.spam-limiter.tab-spam-limit", tabSpamLimit);
     }
 
+    public static int autoRecipeIncrement = 1;
+    public static int autoRecipeLimit = 20;
+    private static void autoRecipieLimiters() {
+        autoRecipeIncrement = getInt("settings.spam-limiter.recipe-spam-increment", autoRecipeIncrement);
+        autoRecipeLimit = getInt("settings.spam-limiter.recipe-spam-limit", autoRecipeLimit);
+    }
+
     public static boolean velocitySupport;
     public static boolean velocityOnlineMode;
     public static byte[] velocitySecretKey;
diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index fbbb5d1019d894e0f05cffb05bcea1e2fdfcbf6e..4d3a427b16e1e0d6889faf4b913b212f8a6e938d 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -1,5 +1,6 @@
 package net.minecraft.server;
 
+import com.destroystokyo.paper.PaperConfig;
 import com.google.common.collect.Lists;
 import com.google.common.primitives.Doubles;
 import com.google.common.primitives.Floats;
@@ -21,7 +22,7 @@ import java.util.function.Consumer;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import javax.annotation.Nullable;
-import org.apache.commons.lang3.StringEscapeUtils;
+
 import org.apache.commons.lang3.StringUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -29,6 +30,8 @@ import org.apache.logging.log4j.Logger;
 // CraftBukkit start
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
+
+import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.craftbukkit.entity.CraftPlayer;
 import org.bukkit.craftbukkit.event.CraftEventFactory;
@@ -85,6 +88,7 @@ public class PlayerConnection implements PacketListenerPlayIn {
     private volatile int chatThrottle;
     private static final AtomicIntegerFieldUpdater chatSpamField = AtomicIntegerFieldUpdater.newUpdater(PlayerConnection.class, "chatThrottle");
     private final java.util.concurrent.atomic.AtomicInteger tabSpamLimiter = new java.util.concurrent.atomic.AtomicInteger(); // Paper - configurable tab spam limits
+    private final java.util.concurrent.atomic.AtomicInteger recipeSpamPackets =  new java.util.concurrent.atomic.AtomicInteger(); // Paper - auto recipe limit
     // CraftBukkit end
     private int j;
     private final Int2ShortMap k = new Int2ShortOpenHashMap();
@@ -233,6 +237,7 @@ public class PlayerConnection implements PacketListenerPlayIn {
         // CraftBukkit start
         for (int spam; (spam = this.chatThrottle) > 0 && !chatSpamField.compareAndSet(this, spam, spam - 1); ) ;
         if (tabSpamLimiter.get() > 0) tabSpamLimiter.getAndDecrement(); // Paper - split to seperate variable
+        if (recipeSpamPackets.get() > 0) recipeSpamPackets.getAndDecrement(); // Paper
         /* Use thread-safe field access instead
         if (this.chatThrottle > 0) {
             --this.chatThrottle;
@@ -2627,6 +2632,14 @@ public class PlayerConnection implements PacketListenerPlayIn {
 
     @Override
     public void a(PacketPlayInAutoRecipe packetplayinautorecipe) {
+        // Paper start
+        if (!Bukkit.isPrimaryThread()) {
+            if (recipeSpamPackets.addAndGet(PaperConfig.autoRecipeIncrement) > PaperConfig.autoRecipeLimit) {
+                minecraftServer.scheduleOnMain(() -> this.disconnect(new ChatMessage("disconnect.spam", new Object[0]))); // Paper
+                return;
+            }
+        }
+        // Paper end
         PlayerConnectionUtils.ensureMainThread(packetplayinautorecipe, this, this.player.getWorldServer());
         this.player.resetIdleTimer();
         if (!this.player.isSpectator() && this.player.activeContainer.windowId == packetplayinautorecipe.b() && this.player.activeContainer.c(this.player) && this.player.activeContainer instanceof ContainerRecipeBook) {