From e4cb9d47b2745b761f6c7fd60914ebdb140c695d Mon Sep 17 00:00:00 2001
From: Johannes Donath <johannesd@torchmind.com>
Date: Sat, 4 Jul 2015 06:31:33 +0200
Subject: [PATCH] Add basic support for configurable tab-complete throttling


diff --git a/api/src/main/java/net/md_5/bungee/api/ProxyConfig.java b/api/src/main/java/net/md_5/bungee/api/ProxyConfig.java
index 6495e7f2..b6845bc4 100644
--- a/api/src/main/java/net/md_5/bungee/api/ProxyConfig.java
+++ b/api/src/main/java/net/md_5/bungee/api/ProxyConfig.java
@@ -130,4 +130,21 @@ public interface ProxyConfig
     // Waterfall Options
     //
 
+    // Throttling options
+
+    /**
+     * How often tab-complete packets can be sent.
+     * <br>
+     * Values in milliseconds.
+     *
+     * @return how often tab-complete packets can be sent in milliseconds
+     */
+    int getTabThrottle();
+
+    /**
+     * Should we disable the tab completion limit for 1.13+ clients
+     *
+     * @return should we disable the tab completion limit for 1.13+ clients
+     */
+    boolean isDisableModernTabLimiter();
 }
diff --git a/proxy/src/main/java/io/github/waterfallmc/waterfall/conf/WaterfallConfiguration.java b/proxy/src/main/java/io/github/waterfallmc/waterfall/conf/WaterfallConfiguration.java
index 741ebfde..91743f01 100644
--- a/proxy/src/main/java/io/github/waterfallmc/waterfall/conf/WaterfallConfiguration.java
+++ b/proxy/src/main/java/io/github/waterfallmc/waterfall/conf/WaterfallConfiguration.java
@@ -7,11 +7,37 @@ import java.io.File;
 
 public class WaterfallConfiguration extends Configuration {
 
+    /*
+     * Throttling options
+     * Helps prevent players from overloading the servers behind us
+     */
+
+    /**
+     * How often players are allowed to send tab throttle.
+     * Value in milliseconds.
+     * <p/>
+     * Default is one packet per second.
+     */
+    private int tabThrottle = 1000;
+    private boolean disableModernTabLimiter = true;
+
     @Override
     public void load() {
         super.load();
         YamlConfig config = new YamlConfig(new File("waterfall.yml"));
         config.load(false); // Load, but no permissions
+        // Throttling options
+        tabThrottle = config.getInt("throttling.tab_complete", tabThrottle);
+        disableModernTabLimiter = config.getBoolean("disable_modern_tab_limiter", disableModernTabLimiter);
     }
 
+    @Override
+    public int getTabThrottle() {
+        return tabThrottle;
+    }
+
+    @Override
+    public boolean isDisableModernTabLimiter() {
+        return disableModernTabLimiter;
+    }
 }
diff --git a/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java b/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
index 460aa491..84be12e5 100644
--- a/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
+++ b/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
@@ -49,6 +49,8 @@ public class UpstreamBridge extends PacketHandler
     private final ProxyServer bungee;
     private final UserConnection con;
 
+    private long lastTabCompletion = -1;
+
     public UpstreamBridge(ProxyServer bungee, UserConnection con)
     {
         this.bungee = bungee;
@@ -222,6 +224,20 @@ public class UpstreamBridge extends PacketHandler
     @Override
     public void handle(TabCompleteRequest tabComplete) throws Exception
     {
+        // Waterfall start - tab limiter
+        if ( bungee.getConfig().getTabThrottle() > 0 &&
+                ( con.getPendingConnection().getVersion() >= ProtocolConstants.MINECRAFT_1_13
+                && !bungee.getConfig().isDisableModernTabLimiter()))
+        {
+            long now = System.currentTimeMillis();
+            if ( lastTabCompletion > 0 && (now - lastTabCompletion) <= bungee.getConfig().getTabThrottle() )
+            {
+                throw CancelSendSignal.INSTANCE;
+            }
+            lastTabCompletion = now;
+        }
+
+        // Waterfall end - tab limiter
         List<String> suggestions = new ArrayList<>();
         boolean isRegisteredCommand = false;
         boolean isCommand = tabComplete.getCursor().startsWith( "/" );
-- 
2.42.1