Waterfall/BungeeCord-Patches/0048-Handle-empty-minecraft-packets.patch

From 7960a4c2a4959570f74e1c931b1d0332a4cd8259 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Tue, 26 Feb 2019 20:15:54 +0000
Subject: [PATCH] Handle empty minecraft packets

Actually detect this and print a message instead of just
throwing exceptions down the line, also includes support
for the "allow empty packets" for completeness, but,
follows the same set of recommendations.

diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java b/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
index 9e9ea49c..a46bbc78 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
@@ -20,11 +20,18 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
     private int protocolVersion;
     @Setter
     private boolean supportsForge = false;
+    private final boolean allowEmptyPackets; // Waterfall
 
     public MinecraftDecoder(Protocol protocol, boolean server, int protocolVersion) {
+        // Waterfall start
+        this(protocol, server, protocolVersion, false);
+    }
+    public MinecraftDecoder(Protocol protocol, boolean server, int protocolVersion, boolean allowEmptyPackets) {
+        // Waterfall end
         this.protocol = protocol;
         this.server = server;
         this.protocolVersion = protocolVersion;
+        this.allowEmptyPackets = allowEmptyPackets; // Waterfall
     }
 
     @Override
@@ -36,6 +43,13 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
         Object packetTypeInfo = null;
         try
         {
+            // Waterfall start
+            if (in.readableBytes() == 0) {
+                if (!allowEmptyPackets) throw new BadPacketException("Empty minecraft packet!");
+                return;
+            }
+            // Waterfall end
+
             int packetId = DefinedPacket.readVarInt( in );
             packetTypeInfo = packetId;
 
diff --git a/proxy/src/main/java/net/md_5/bungee/UserConnection.java b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
index 8a524a64..e649678e 100644
--- a/proxy/src/main/java/net/md_5/bungee/UserConnection.java
+++ b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
@@ -351,7 +351,7 @@ public final class UserConnection implements ProxiedPlayer
             protected void initChannel(Channel ch) throws Exception
             {
                 PipelineUtils.BASE.initChannel( ch );
-                ch.pipeline().addAfter( PipelineUtils.FRAME_DECODER, PipelineUtils.PACKET_DECODER, new MinecraftDecoder( Protocol.HANDSHAKE, false, getPendingConnection().getVersion() ) );
+                ch.pipeline().addAfter( PipelineUtils.FRAME_DECODER, PipelineUtils.PACKET_DECODER, new MinecraftDecoder( Protocol.HANDSHAKE, false, getPendingConnection().getVersion(), bungee.getConfig().isAllowEmptyPackets() ) ); // Waterfall
                 ch.pipeline().addAfter( PipelineUtils.FRAME_PREPENDER, PipelineUtils.PACKET_ENCODER, new MinecraftEncoder( Protocol.HANDSHAKE, false, getPendingConnection().getVersion() ) );
                 ch.pipeline().get( HandlerBoss.class ).setHandler( new ServerConnector( bungee, UserConnection.this, target ) );
             }
-- 
2.21.0