Improve Quality of Channel Close Code

* Don't double disconnect due to client exceptions
* Add generic delayed close method
* Properly format imports in changed files

proxy/src/main/java/net/md_5/bungee/UserConnection.java

@@ -11,17 +11,14 @@ import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
 import io.netty.util.internal.PlatformDependent;
 import java.net.InetSocketAddress;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
-import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Queue;
 import java.util.UUID;
-import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import lombok.Getter;
 import lombok.NonNull;
@@ -59,8 +56,6 @@ import net.md_5.bungee.protocol.packet.Kick;
 import net.md_5.bungee.protocol.packet.PlayerListHeaderFooter;
 import net.md_5.bungee.protocol.packet.PluginMessage;
 import net.md_5.bungee.protocol.packet.SetCompression;
-import net.md_5.bungee.tab.Global;
-import net.md_5.bungee.tab.GlobalPing;
 import net.md_5.bungee.tab.ServerUnique;
 import net.md_5.bungee.tab.TabList;
 import net.md_5.bungee.util.CaseInsensitiveSet;
@@ -364,31 +359,26 @@ public final class UserConnection implements ProxiedPlayer
 
     public void disconnect0(final BaseComponent... reason)
     {
-        if ( !ch.isClosed() )
+        if ( !ch.isClosing() )
         {
             bungee.getLogger().log( Level.INFO, "[{0}] disconnected with: {1}", new Object[]
             {
                 getName(), BaseComponent.toLegacyText( reason )
             } );
 
-            // Why do we have to delay this you might ask? Well the simple reason is MOJANG.
+            ch.delayedClose( new Runnable()
-            // Despite many a bug report posted, ever since the 1.7 protocol rewrite, the client STILL has a race condition upon switching protocols.
-            // As such, despite the protocol switch packets already having been sent, there is the possibility of a client side exception
-            // To help combat this we will wait half a second before actually sending the disconnected packet so that whoever is on the other
-            // end has a somewhat better chance of receiving the proper packet.
-            ch.getHandle().eventLoop().schedule( new Runnable()
             {
 
                 @Override
                 public void run()
                 {
                     unsafe().sendPacket( new Kick( ComponentSerializer.toString( reason ) ) );
-                    ch.close();
                 }
-            }, 500, TimeUnit.MILLISECONDS );
+            } );
 
             if ( server != null )
             {
+                server.setObsolete( true );
                 server.disconnect( "Quitting" );
             }
         }

proxy/src/main/java/net/md_5/bungee/connection/InitialHandler.java

@@ -2,19 +2,24 @@ package net.md_5.bungee.connection;
 
 import com.google.common.base.Charsets;
 import com.google.common.base.Preconditions;
+import com.google.gson.Gson;
 import java.math.BigInteger;
 import java.net.InetSocketAddress;
 import java.net.URLEncoder;
 import java.security.MessageDigest;
 import java.util.List;
 import java.util.UUID;
+import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import javax.crypto.SecretKey;
-import com.google.gson.Gson;
-import java.util.concurrent.TimeUnit;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
-import net.md_5.bungee.*;
+import net.md_5.bungee.BungeeCord;
+import net.md_5.bungee.BungeeServerInfo;
+import net.md_5.bungee.EncryptionUtil;
+import net.md_5.bungee.UserConnection;
+import net.md_5.bungee.Util;
+import net.md_5.bungee.api.AbstractReconnectHandler;
 import net.md_5.bungee.api.Callback;
 import net.md_5.bungee.api.ChatColor;
 import net.md_5.bungee.api.Favicon;
@@ -23,37 +28,37 @@ import net.md_5.bungee.api.chat.BaseComponent;
 import net.md_5.bungee.api.chat.TextComponent;
 import net.md_5.bungee.api.config.ListenerInfo;
 import net.md_5.bungee.api.config.ServerInfo;
+import net.md_5.bungee.api.connection.Connection.Unsafe;
 import net.md_5.bungee.api.connection.PendingConnection;
 import net.md_5.bungee.api.connection.ProxiedPlayer;
 import net.md_5.bungee.api.event.LoginEvent;
+import net.md_5.bungee.api.event.PlayerHandshakeEvent;
 import net.md_5.bungee.api.event.PostLoginEvent;
+import net.md_5.bungee.api.event.PreLoginEvent;
 import net.md_5.bungee.api.event.ProxyPingEvent;
 import net.md_5.bungee.chat.ComponentSerializer;
 import net.md_5.bungee.http.HttpClient;
-import net.md_5.bungee.netty.HandlerBoss;
+import net.md_5.bungee.jni.cipher.BungeeCipher;
 import net.md_5.bungee.netty.ChannelWrapper;
+import net.md_5.bungee.netty.HandlerBoss;
 import net.md_5.bungee.netty.PacketHandler;
 import net.md_5.bungee.netty.PipelineUtils;
 import net.md_5.bungee.netty.cipher.CipherDecoder;
 import net.md_5.bungee.netty.cipher.CipherEncoder;
 import net.md_5.bungee.protocol.DefinedPacket;
 import net.md_5.bungee.protocol.PacketWrapper;
-import net.md_5.bungee.protocol.ProtocolConstants;
-import net.md_5.bungee.protocol.packet.Handshake;
-import net.md_5.bungee.protocol.packet.PluginMessage;
-import net.md_5.bungee.protocol.packet.EncryptionResponse;
-import net.md_5.bungee.protocol.packet.EncryptionRequest;
-import net.md_5.bungee.protocol.packet.Kick;
-import net.md_5.bungee.api.AbstractReconnectHandler;
-import net.md_5.bungee.api.event.PlayerHandshakeEvent;
-import net.md_5.bungee.api.event.PreLoginEvent;
-import net.md_5.bungee.jni.cipher.BungeeCipher;
 import net.md_5.bungee.protocol.Protocol;
+import net.md_5.bungee.protocol.ProtocolConstants;
+import net.md_5.bungee.protocol.packet.EncryptionRequest;
+import net.md_5.bungee.protocol.packet.EncryptionResponse;
+import net.md_5.bungee.protocol.packet.Handshake;
+import net.md_5.bungee.protocol.packet.Kick;
 import net.md_5.bungee.protocol.packet.LegacyHandshake;
 import net.md_5.bungee.protocol.packet.LegacyPing;
 import net.md_5.bungee.protocol.packet.LoginRequest;
 import net.md_5.bungee.protocol.packet.LoginSuccess;
 import net.md_5.bungee.protocol.packet.PingPacket;
+import net.md_5.bungee.protocol.packet.PluginMessage;
 import net.md_5.bungee.protocol.packet.StatusRequest;
 import net.md_5.bungee.protocol.packet.StatusResponse;
 import net.md_5.bungee.util.BoundedArrayList;
@@ -96,12 +101,11 @@ public class InitialHandler extends PacketHandler implements PendingConnection
     private boolean legacy;
     @Getter
     private String extraDataInHandshake = "";
-    private boolean disconnecting;
 
     @Override
     public boolean shouldHandle(PacketWrapper packet) throws Exception
     {
-        return !disconnecting;
+        return !ch.isClosing();
     }
 
     private enum State
@@ -534,15 +538,7 @@ public class InitialHandler extends PacketHandler implements PendingConnection
     @Override
     public void disconnect(final BaseComponent... reason)
     {
-        if ( !disconnecting || !ch.isClosed() )
+        ch.delayedClose( new Runnable()
-        {
-            disconnecting = true;
-            // Why do we have to delay this you might ask? Well the simple reason is MOJANG.
-            // Despite many a bug report posted, ever since the 1.7 protocol rewrite, the client STILL has a race condition upon switching protocols.
-            // As such, despite the protocol switch packets already having been sent, there is the possibility of a client side exception
-            // To help combat this we will wait half a second before actually sending the disconnected packet so that whoever is on the other
-            // end has a somewhat better chance of receiving the proper packet.
-            ch.getHandle().eventLoop().schedule( new Runnable()
         {
 
             @Override
@@ -552,10 +548,8 @@ public class InitialHandler extends PacketHandler implements PendingConnection
                 {
                     unsafe().sendPacket( new Kick( ComponentSerializer.toString( reason ) ) );
                 }
-                    ch.close();
-                }
-            }, 500, TimeUnit.MILLISECONDS );
             }
+        } );
     }
 
     @Override

proxy/src/main/java/net/md_5/bungee/netty/ChannelWrapper.java

@@ -1,15 +1,16 @@
 package net.md_5.bungee.netty;
 
-import net.md_5.bungee.compress.PacketCompressor;
-import net.md_5.bungee.compress.PacketDecompressor;
-import net.md_5.bungee.protocol.PacketWrapper;
 import com.google.common.base.Preconditions;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
+import java.util.concurrent.TimeUnit;
 import lombok.Getter;
+import net.md_5.bungee.compress.PacketCompressor;
+import net.md_5.bungee.compress.PacketDecompressor;
 import net.md_5.bungee.protocol.MinecraftDecoder;
 import net.md_5.bungee.protocol.MinecraftEncoder;
+import net.md_5.bungee.protocol.PacketWrapper;
 import net.md_5.bungee.protocol.Protocol;
 
 public class ChannelWrapper
@@ -18,6 +19,8 @@ public class ChannelWrapper
     private final Channel ch;
     @Getter
     private volatile boolean closed;
+    @Getter
+    private volatile boolean closing;
 
     public ChannelWrapper(ChannelHandlerContext ctx)
     {
@@ -56,12 +59,41 @@ public class ChannelWrapper
     {
         if ( !closed )
         {
-            closed = true;
+            closed = closing = true;
             ch.flush();
             ch.close();
         }
     }
 
+    public void delayedClose(final Runnable runnable)
+    {
+        Preconditions.checkArgument( runnable != null, "runnable" );
+
+        if ( !closing )
+        {
+            closing = true;
+
+            // Minecraft client can take some time to switch protocols.
+            // Sending the wrong disconnect packet whilst a protocol switch is in progress will crash it.
+            // Delay 500ms to ensure that the protocol switch (if any) has definitely taken place.
+            ch.eventLoop().schedule( new Runnable()
+            {
+
+                @Override
+                public void run()
+                {
+                    try
+                    {
+                        runnable.run();
+                    } finally
+                    {
+                        ChannelWrapper.this.close();
+                    }
+                }
+            }, 500, TimeUnit.MILLISECONDS );
+        }
+    }
+
     public void addBefore(String baseName, String name, ChannelHandler handler)
     {
         Preconditions.checkState( ch.eventLoop().inEventLoop(), "cannot add handler outside of event loop" );