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 1c243b60bf955841d69d1a5ace9d243edf88a6fb..19f05a2d202e3b71391d20acbf54392f644978e4 100644
--- a/src/main/java/net/minecraft/network/ConnectionProtocol.java
+++ b/src/main/java/net/minecraft/network/ConnectionProtocol.java
@@ -300,6 +300,7 @@ public enum ConnectionProtocol {
 
         @Nullable
         public Packet<?> createPacket(int id, FriendlyByteBuf buf) {
+            if (id < 0 || id >= this.idToDeserializer.size()) return null; // Paper
             Function<FriendlyByteBuf, ? extends Packet<T>> function = this.idToDeserializer.get(id);
             return function != null ? function.apply(buf) : null;
         }
diff --git a/src/main/java/net/minecraft/network/Varint21FrameDecoder.java b/src/main/java/net/minecraft/network/Varint21FrameDecoder.java
index 99b581052f937b0f2d6b5d73de699008c1d51774..81ec2011a93bb94200ad750f4666ba1cd8be11c5 100644
--- a/src/main/java/net/minecraft/network/Varint21FrameDecoder.java
+++ b/src/main/java/net/minecraft/network/Varint21FrameDecoder.java
@@ -8,9 +8,20 @@ import io.netty.handler.codec.CorruptedFrameException;
 import java.util.List;
 
 public class Varint21FrameDecoder extends ByteToMessageDecoder {
+    private final byte[] lenBuf = new byte[3]; // Paper
+    @Override
     protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) {
+        // 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[] bs = new byte[3];
+        // Paper start - reuse temporary length buffer
+        byte[] bs = lenBuf;
+        java.util.Arrays.fill(bs, (byte) 0);
+        // Paper end
 
         for(int i = 0; i < bs.length; ++i) {
             if (!byteBuf.isReadable()) {
diff --git a/src/main/java/net/minecraft/network/protocol/PacketUtils.java b/src/main/java/net/minecraft/network/protocol/PacketUtils.java
index 049e64c355d5f064009b1107ad15d28c44f999dd..acfa1907bfc9c29d261cfccc00d65bad9ad1a002 100644
--- a/src/main/java/net/minecraft/network/protocol/PacketUtils.java
+++ b/src/main/java/net/minecraft/network/protocol/PacketUtils.java
@@ -30,11 +30,15 @@ public class PacketUtils {
                     try (co.aikar.timings.Timing ignored = timing.startTiming()) { // Paper - timings
                         packet.handle(listener);
                     } catch (Exception exception) {
-                        if (listener.shouldPropagateHandlingExceptions()) {
-                            throw exception;
+                        net.minecraft.network.Connection networkmanager = listener.getConnection();
+                        if (networkmanager.getPlayer() != null) {
+                            LOGGER.error("Error whilst processing packet {} for {}[{}]", packet, networkmanager.getPlayer().getScoreboardName(), networkmanager.getRemoteAddress(), exception);
+                        } else {
+                            LOGGER.error("Error whilst processing packet {} for connection from {}", packet, networkmanager.getRemoteAddress(), exception);
                         }
-
-                        PacketUtils.LOGGER.error("Failed to handle packet {}, suppressing error", packet, exception);
+                        net.minecraft.network.chat.Component error = net.minecraft.network.chat.Component.literal("Packet processing error");
+                        networkmanager.send(new net.minecraft.network.protocol.game.ClientboundDisconnectPacket(error), net.minecraft.network.PacketSendListener.thenRun(() -> networkmanager.disconnect(error)));
+                        networkmanager.setReadOnly();
                     }
                 } else {
                     PacketUtils.LOGGER.debug("Ignoring packet due to disconnection: {}", packet);
