Fix for edgecase FML|HS packet desynchronization (PaperMC#948)

* Fix for edgecase FML|HS packet desynchronization * Change approach for FML packet desynchronization edge case
CoreyShupe · Feb 15, 2023 · cd35e8f · cd35e8f
1 parent 8761d02
commit cd35e8f
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/...y/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java b/...y/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java
@@ -40,6 +40,7 @@
 import com.velocitypowered.proxy.connection.backend.BackendConnectionPhases;
 import com.velocitypowered.proxy.connection.backend.BungeeCordMessageResponder;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
+import com.velocitypowered.proxy.connection.forge.legacy.LegacyForgeConstants;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
@@ -277,7 +278,14 @@ public boolean handle(TabCompleteRequest packet) {
 
   @Override
   public boolean handle(PluginMessage packet) {
-    VelocityServerConnection serverConn = player.getConnectedServer();
+    // Handling edge case when packet with FML client handshake (state COMPLETE)
+    // arrives after JoinGame packet from destination server
+    VelocityServerConnection serverConn =
+            (player.getConnectedServer() == null
+                    && packet.getChannel().equals(
+                            LegacyForgeConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL))
+            ? player.getConnectionInFlight() : player.getConnectedServer();
+
     MinecraftConnection backendConn = serverConn != null ? serverConn.getConnection() : null;
     if (serverConn != null && backendConn != null) {
       if (backendConn.getState() != StateRegistry.PLAY) {