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/ConnectionProtocol.java b/src/main/java/net/minecraft/network/ConnectionProtocol.java
index fca778d131aa10e88d5f7ed8d57eda6803318184..47a5ee9db64184f173af5984765e9b6d1a8ec367 100644
--- a/src/main/java/net/minecraft/network/ConnectionProtocol.java
+++ b/src/main/java/net/minecraft/network/ConnectionProtocol.java
@@ -151,6 +151,7 @@ public enum ConnectionProtocol {
 
         @Nullable
         public Packet<?> createPacket(int id) {
+            if (id < 0 || id >= this.idToConstructor.size()) return null; // Paper
             Supplier<? extends Packet<T>> supplier = (Supplier) this.idToConstructor.get(id);
 
             return supplier != null ? (Packet) supplier.get() : null;
diff --git a/src/main/java/net/minecraft/network/Varint21FrameDecoder.java b/src/main/java/net/minecraft/network/Varint21FrameDecoder.java
index 8363b63f8dbd16948eeba3f912dc43605ad8db6a..fbebef6525a0872fecc081c7f63f27c1a04e11dc 100644
--- a/src/main/java/net/minecraft/network/Varint21FrameDecoder.java
+++ b/src/main/java/net/minecraft/network/Varint21FrameDecoder.java
@@ -9,11 +9,21 @@ import java.util.List;
 
 public class Varint21FrameDecoder extends ByteToMessageDecoder {
 
+    private final byte[] lenBuf = new byte[3]; // Paper
     public Varint21FrameDecoder() {}
 
     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 22db5d0d2cc33498ca40162c66aa3b5fbf2f569f..3163502cb9bbbb5a00e7f06cf0032b1ad93c354d 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.Connection;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.network.PacketListener;
+import net.minecraft.server.level.ServerPlayer;
 
 public interface Packet<T extends PacketListener> {
 
@@ -18,17 +20,17 @@ public interface Packet<T extends PacketListener> {
     /**
      * @param player Null if not at PLAY stage yet
      */
-    default void onPacketDispatch(@javax.annotation.Nullable EntityPlayer player) {}
+    default void onPacketDispatch(@javax.annotation.Nullable ServerPlayer player) {}
 
     /**
      * @param player Null if not at PLAY stage yet
      * @param future Can be null if packet was cancelled
      */
-    default void onPacketDispatchFinish(@javax.annotation.Nullable EntityPlayer player, @javax.annotation.Nullable ChannelFuture future) {}
+    default void onPacketDispatchFinish(@javax.annotation.Nullable ServerPlayer player, @javax.annotation.Nullable ChannelFuture future) {}
     default boolean hasFinishListener() { return false; }
     default boolean isReady() { return true; }
     default java.util.List<Packet> getExtraPackets() { return null; }
-    default boolean packetTooLarge(NetworkManager manager) {
+    default boolean packetTooLarge(Connection manager) {
         return false;
     }
     // Paper end
diff --git a/src/main/java/net/minecraft/network/protocol/PacketUtils.java b/src/main/java/net/minecraft/network/protocol/PacketUtils.java
index 4ae8201d7dcffeb3298a4e593f978e15ffc5ac15..5812e518222e419da141ab0f70d1e7a3939a0df0 100644
--- a/src/main/java/net/minecraft/network/protocol/PacketUtils.java
+++ b/src/main/java/net/minecraft/network/protocol/PacketUtils.java
@@ -1,6 +1,9 @@
 package net.minecraft.network.protocol;
 
+import net.minecraft.network.Connection;
 import net.minecraft.network.PacketListener;
+import net.minecraft.network.chat.TextComponent;
+import net.minecraft.network.protocol.game.ClientboundDisconnectPacket;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import co.aikar.timings.MinecraftTimings; // Paper
@@ -30,6 +33,21 @@ public class PacketUtils {
                     try (Timing ignored = timing.startTiming()) { // Paper - timings
                     packet.handle(listener);
                     } // Paper - timings
+                    // Paper start
+                    catch (Exception e) {
+                        Connection networkmanager = listener.a();
+                        if (networkmanager.getPlayer() != null) {
+                            LOGGER.error("Error whilst processing packet {} for {}[{}]", packet, networkmanager.getPlayer().getScoreboardName(), networkmanager.getRemoteAddress(), e);
+                        } else {
+                            LOGGER.error("Error whilst processing packet {} for connection from {}", packet, networkmanager.getRemoteAddress(), e);
+                        }
+                        TextComponent error = new TextComponent("Packet processing error");
+                        networkmanager.send(new ClientboundDisconnectPacket(error), (future) -> {
+                            networkmanager.disconnect(error);
+                        });
+                        networkmanager.setReadOnly();
+                    }
+                    // Paper end
                 } else {
                     PacketUtils.LOGGER.debug("Ignoring packet due to disconnection: " + packet);
                 }