PaperMC/Spigot-Server-Patches/0240-handle-PacketPlayInKeepAlive-async.patch

From 336d31b126a2d9cdc3cb53fbe1ef71af40c9da81 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Thu, 5 Oct 2017 01:54:07 +0100
Subject: [PATCH] handle PacketPlayInKeepAlive async

In 1.12.2, Mojang moved the processing of PacketPlayInKeepAlive off the main
thread, while entirely correct for the server, this causes issues with
plugins which are expecting the PlayerQuitEvent on the main thread.

In order to counteract some bad behavior, we will post handling of the
disconnection to the main thread, but leave the actual processing of the packet
off the main thread.

also adding some additional logging in order to help work out what is causing
random disconnections for clients.

diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index aa57ff8ed..869a2b402 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -2230,14 +2230,20 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
     }
 
     public void a(PacketPlayInKeepAlive packetplayinkeepalive) {
-        PlayerConnectionUtils.ensureMainThread(packetplayinkeepalive, this, this.player.x()); // CraftBukkit
+        //PlayerConnectionUtils.ensureMainThread(packetplayinkeepalive, this, this.player.x()); // CraftBukkit // Paper - This shouldn't be on the main thread
         if (this.g && packetplayinkeepalive.a() == this.h) {
             int i = (int) (this.d() - this.f);
 
             this.player.ping = (this.player.ping * 3 + i) / 4;
             this.g = false;
         } else if (!this.player.getName().equals(this.minecraftServer.Q())) {
-            this.disconnect(new ChatMessage("disconnect.timeout", new Object[0]));
+            // Paper start - This needs to be handled on the main thread for plugins
+            PlayerConnection.LOGGER.warn("{} sent an invalid keepalive! pending keepalive: {} got id: {} expected id: {}",
+                    this.player.getName(), this.isPendingPing(), packetplayinkeepalive.a(), this.getKeepAliveID());
+            minecraftServer.postToMainThread(() -> {
+                    this.disconnect(new ChatMessage("disconnect.timeout", new Object[0]));
+            });
+            // Paper end
         }
 
     }
-- 
2.16.2