From f82212d687248903ef0e0b2ec58013f9c3c5b7ee Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Sun, 29 Jul 2018 05:02:15 +0100
Subject: [PATCH] Break up and make tab spam limits configurable

Due to the changes in 1.13, clients will send a tab completion request
for all bukkit commands in order to factor in the lack of support for
brigadier and provide backwards support in the API.

Craftbukkit, however; has moved the chat spam limiter to also interact
with the tab completion request, which while good for avoiding abuse,
causes 1.13 clients to easilly be kicked from a server in bukkit due
to this. Removing the spam limit could cause issues for servers, however,
there is no way for servers to manipulate this without blindly cancelling
kick events, which only causes additional complications. This also causes
issues in that the tab spam limit and chat share the same field but different
limits, meaning that a player having typed a long command may be kicked from
the server.

Splitting the field up and making it configurable allows for server owners
to take the burden of this into their own hand without having to rely on
plugins doing unsafe things.

diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
index c457d07110..046bf33f66 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -327,4 +327,18 @@ public class PaperConfig {
             logger.log(Level.INFO, "******************************************************");
         }
     }
+
+    public static int tabSpamIncrement = 2;
+    public static int tabSpamLimit = 500;
+    private static void tabSpamLimiters() {
+        tabSpamIncrement = getInt("settings.spam-limiter.tab-spam-increment", tabSpamIncrement);
+        // Older versions used a smaller limit, which is too low for 1.13, we'll bump this up if default
+        if (version < 14) {
+            if (tabSpamIncrement == 10) {
+                set("settings.spam-limiter.tab-spam-increment", 2);
+                tabSpamIncrement = 2;
+            }
+        }
+        tabSpamLimit = getInt("settings.spam-limiter.tab-spam-limit", tabSpamLimit);
+    }
 }
diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index 66e01b8131..b7949ac256 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -77,6 +77,7 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
     // CraftBukkit start - multithreaded fields
     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
     // CraftBukkit end
     private int j;
     private final IntHashMap<Short> k = new IntHashMap();
@@ -206,6 +207,7 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
         this.minecraftServer.methodProfiler.e();
         // 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
         /* Use thread-safe field access instead
         if (this.chatThrottle > 0) {
             --this.chatThrottle;
@@ -508,7 +510,7 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
     public void a(PacketPlayInTabComplete packetplayintabcomplete) {
         // PlayerConnectionUtils.ensureMainThread(packetplayintabcomplete, this, this.player.getWorldServer()); // Paper - run this async
         // CraftBukkit start
-        if (chatSpamField.addAndGet(this, 2) > 500 && !this.minecraftServer.getPlayerList().isOp(this.player.getProfile())) {
+        if (tabSpamLimiter.addAndGet(com.destroystokyo.paper.PaperConfig.tabSpamIncrement) > com.destroystokyo.paper.PaperConfig.tabSpamLimit && !this.minecraftServer.getPlayerList().isOp(this.player.getProfile())) { // Paper start - split and make configurable
             this.disconnect(new ChatMessage("disconnect.spam", new Object[0]));
             minecraftServer.postToMainThread(() -> this.disconnect(new ChatMessage("disconnect.spam", new Object[0]))); // Paper
             return;
-- 
2.18.0