From e7ed66477fbc7fcf17d66db49d6db8e01acafb33 Mon Sep 17 00:00:00 2001
From: KingRainbow44 <kobedo11@gmail.com>
Date: Sat, 6 Jul 2024 22:54:10 -0400
Subject: [PATCH] fix(networking): Prevent hanging the network loop if an
 exception occurs

---
 .../net/impl/NetworkTransportImpl.java           | 16 +++++++++++++---
 .../emu/grasscutter/server/game/GameSession.java |  5 +++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/main/java/emu/grasscutter/net/impl/NetworkTransportImpl.java b/src/main/java/emu/grasscutter/net/impl/NetworkTransportImpl.java
index 7d2837147..afdb91ecc 100644
--- a/src/main/java/emu/grasscutter/net/impl/NetworkTransportImpl.java
+++ b/src/main/java/emu/grasscutter/net/impl/NetworkTransportImpl.java
@@ -2,6 +2,7 @@ package emu.grasscutter.net.impl;
 
 import emu.grasscutter.net.INetworkTransport;
 import emu.grasscutter.server.game.GameSession;
+import emu.grasscutter.utils.Utils;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.DefaultEventLoop;
 import io.netty.channel.EventLoop;
@@ -83,11 +84,20 @@ public class NetworkTransportImpl extends KcpServer implements INetworkTransport
                     return;
                 }
 
-                transport.networkLoop.submit(() -> session.onReceived(byteBuf.array()));
+                // Copy the buffer to avoid reference issues.
+                var data = Utils.byteBufToArray(byteBuf);
+
+                transport.networkLoop.submit(() -> {
+                    // Fun fact: if we don't catch exceptions here,
+                    // we run the risk of locking the entire network loop.
+                    try {
+                        session.onReceived(data);
+                    } catch (Exception ex) {
+                        session.getLogger().warn("Unable to handle received data.", ex);
+                    }
+                });
             } catch (Exception ex) {
                 NetworkTransportImpl.log.warn("Unable to handle received data.", ex);
-            } finally {
-                byteBuf.release();
             }
         }
 
diff --git a/src/main/java/emu/grasscutter/server/game/GameSession.java b/src/main/java/emu/grasscutter/server/game/GameSession.java
index 7115317a5..f035eca21 100644
--- a/src/main/java/emu/grasscutter/server/game/GameSession.java
+++ b/src/main/java/emu/grasscutter/server/game/GameSession.java
@@ -14,6 +14,7 @@ import emu.grasscutter.utils.*;
 import io.netty.buffer.*;
 import java.net.InetSocketAddress;
 import lombok.*;
+import org.slf4j.Logger;
 
 public class GameSession implements IGameSession {
     @Getter private final GameServer server;
@@ -49,6 +50,10 @@ public class GameSession implements IGameSession {
         return this.session.getAddress();
     }
 
+    public Logger getLogger() {
+        return this.session.getLogger();
+    }
+
     public synchronized void setPlayer(Player player) {
         this.player = player;
         this.player.setSession(this);