From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Sun, 5 Jul 2020 22:38:18 -0400
Subject: [PATCH] Optimize NetworkManager Exception Handling


diff --git a/src/main/java/net/minecraft/network/EnumProtocol.java b/src/main/java/net/minecraft/network/EnumProtocol.java
index a892521db1197369bf6363bd2f5da24bf53643ab..46d8471ba98a5f2c659d35dd86c4c20c67f1ceac 100644
--- a/src/main/java/net/minecraft/network/EnumProtocol.java
+++ b/src/main/java/net/minecraft/network/EnumProtocol.java
@@ -286,6 +286,7 @@ public enum EnumProtocol {
 
         @Nullable
         public Packet<?> a(int i) {
+            if (i < 0 || i >= this.b.size()) return null; // Paper
             Supplier<? extends Packet<T>> supplier = (Supplier) this.b.get(i);
 
             return supplier != null ? (Packet) supplier.get() : null;
diff --git a/src/main/java/net/minecraft/network/PacketSplitter.java b/src/main/java/net/minecraft/network/PacketSplitter.java
index 2c7de7ab6da2106394ec668cd7cb9be1f8dabeb3..e81bfd35b9a745eeb1457ceda5fda320654bd89a 100644
--- a/src/main/java/net/minecraft/network/PacketSplitter.java
+++ b/src/main/java/net/minecraft/network/PacketSplitter.java
@@ -9,11 +9,21 @@ import java.util.List;
 
 public class PacketSplitter extends ByteToMessageDecoder {
 
+    private final byte[] lenBuf = new byte[3]; // Paper
     public PacketSplitter() {}
 
     protected void decode(ChannelHandlerContext channelhandlercontext, ByteBuf bytebuf, List<Object> list) throws Exception {
+        // Paper start - if channel is not active just discard the packet
+        if (!channelhandlercontext.channel().isActive()) {
+            bytebuf.skipBytes(bytebuf.readableBytes());
+            return;
+        }
+        // Paper end
         bytebuf.markReaderIndex();
-        byte[] abyte = new byte[3];
+        // Paper start - reuse temporary length buffer
+        byte[] abyte = lenBuf;
+        java.util.Arrays.fill(abyte, (byte) 0);
+        // Paper end
 
         for (int i = 0; i < abyte.length; ++i) {
             if (!bytebuf.isReadable()) {
diff --git a/src/main/java/net/minecraft/network/protocol/Packet.java b/src/main/java/net/minecraft/network/protocol/Packet.java
index b644c91cecd8a347319dfe8c8923fd05919a9795..4c583593de4dc8ab27b3e1187f4dfe1740ef07a7 100644
--- a/src/main/java/net/minecraft/network/protocol/Packet.java
+++ b/src/main/java/net/minecraft/network/protocol/Packet.java
@@ -2,8 +2,10 @@ package net.minecraft.network.protocol;
 
 import io.netty.channel.ChannelFuture; // Paper
 import java.io.IOException;
+import net.minecraft.network.NetworkManager;
 import net.minecraft.network.PacketDataSerializer;
 import net.minecraft.network.PacketListener;
+import net.minecraft.server.level.EntityPlayer;
 
 public interface Packet<T extends PacketListener> {
 
diff --git a/src/main/java/net/minecraft/network/protocol/PlayerConnectionUtils.java b/src/main/java/net/minecraft/network/protocol/PlayerConnectionUtils.java
index e47da20ab8ce4da34755e105bf55d8542fb50138..67d8fe8ad036a9252c774bb6a914c8ec79981876 100644
--- a/src/main/java/net/minecraft/network/protocol/PlayerConnectionUtils.java
+++ b/src/main/java/net/minecraft/network/protocol/PlayerConnectionUtils.java
@@ -1,6 +1,9 @@
 package net.minecraft.network.protocol;
 
+import net.minecraft.network.NetworkManager;
 import net.minecraft.network.PacketListener;
+import net.minecraft.network.chat.ChatComponentText;
+import net.minecraft.network.protocol.game.PacketPlayOutKickDisconnect;
 import net.minecraft.server.CancelledPacketHandleException;
 import net.minecraft.server.level.WorldServer;
 import net.minecraft.util.thread.IAsyncTaskHandler;
@@ -31,6 +34,21 @@ public class PlayerConnectionUtils {
                     try (Timing ignored = timing.startTiming()) { // Paper - timings
                     packet.a(t0);
                     } // Paper - timings
+                    // Paper start
+                    catch (Exception e) {
+                        NetworkManager networkmanager = t0.a();
+                        if (networkmanager.getPlayer() != null) {
+                            LOGGER.error("Error whilst processing packet {} for {}[{}]", packet, networkmanager.getPlayer().getName(), networkmanager.getSocketAddress(), e);
+                        } else {
+                            LOGGER.error("Error whilst processing packet {} for connection from {}", packet, networkmanager.getSocketAddress(), e);
+                        }
+                        ChatComponentText error = new ChatComponentText("Packet processing error");
+                        networkmanager.sendPacket(new PacketPlayOutKickDisconnect(error), (future) -> {
+                            networkmanager.close(error);
+                        });
+                        networkmanager.stopReading();
+                    }
+                    // Paper end
                 } else {
                     PlayerConnectionUtils.LOGGER.debug("Ignoring packet due to disconnection: " + packet);
                 }