PaperMC/CraftBukkit-Patches/0113-Fix-race-condition-that-could-kill-connections-befor.patch

From 75076bfbbe1016773c9c4d87a2ad4d8f7b50d2e4 Mon Sep 17 00:00:00 2001
From: Jonas Konrad <me@yawk.at>
Date: Fri, 25 Apr 2014 23:46:46 +0200
Subject: [PATCH] Fix race condition that could kill connections before they
 were initiated

Because NetworkManagers are registered before they get their channel in
channelActive, the ServerConnection would remove them sometimes because
it thought they were disconnected. This commit fixes this by introducing
a 'preparing' variable that is true while the NetworkManager is not
initialized. The ServerConnection does not remove NetworkManagers with
this flag.

diff --git a/src/main/java/net/minecraft/server/NetworkManager.java b/src/main/java/net/minecraft/server/NetworkManager.java
index f26d377..247973d 100644
--- a/src/main/java/net/minecraft/server/NetworkManager.java
+++ b/src/main/java/net/minecraft/server/NetworkManager.java
@@ -68,6 +68,7 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet> {
     public SocketAddress l;
     public java.util.UUID spoofedUUID;
     public com.mojang.authlib.properties.Property[] spoofedProfile;
+    public boolean preparing = true;
     // Spigot End
     private PacketListener m;
     private IChatBaseComponent n;
@@ -82,6 +83,9 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet> {
         super.channelActive(channelhandlercontext);
         this.channel = channelhandlercontext.channel();
         this.l = this.channel.remoteAddress();
+        // Spigot Start
+        this.preparing = false;
+        // Spigot End
 
         try {
             this.a(EnumProtocol.HANDSHAKING);
@@ -235,6 +239,9 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet> {
     }
 
     public void close(IChatBaseComponent ichatbasecomponent) {
+        // Spigot Start
+        this.preparing = false;
+        // Spigot End
         if (this.channel.isOpen()) {
             this.channel.close(); // We can't wait as this may be called from an event loop.
             this.n = ichatbasecomponent;
diff --git a/src/main/java/net/minecraft/server/ServerConnection.java b/src/main/java/net/minecraft/server/ServerConnection.java
index cfd4ca1..f13182c 100644
--- a/src/main/java/net/minecraft/server/ServerConnection.java
+++ b/src/main/java/net/minecraft/server/ServerConnection.java
@@ -137,6 +137,10 @@ public class ServerConnection {
 
                 if (!networkmanager.h()) {
                     if (!networkmanager.g()) {
+                        // Spigot Start
+                        // Fix a race condition where a NetworkManager could be unregistered just before connection.
+                        if (networkmanager.preparing) continue;
+                        // Spigot End
                         iterator.remove();
                         networkmanager.l();
                     } else {
-- 
2.1.4