Retrieve and use Floodgate username in Velocity PreLoginEvent

velocity/src/main/java/com/github/games647/fastlogin/velocity/FastLoginVelocity.java

@@ -230,4 +230,8 @@ public class FastLoginVelocity implements PlatformPlugin<CommandSource> {
     public UUID getProxyId() {
         return proxyId;
     }
+
+    public ProxyServer getServer() {
+        return server;
+    }
 }

velocity/src/main/java/com/github/games647/fastlogin/velocity/listener/ConnectListener.java

@@ -36,6 +36,8 @@ import com.github.games647.fastlogin.velocity.VelocityLoginSession;
 import com.github.games647.fastlogin.velocity.task.AsyncPremiumCheck;
 import com.github.games647.fastlogin.velocity.task.FloodgateAuthTask;
 import com.github.games647.fastlogin.velocity.task.ForceLoginTask;
+import com.google.common.cache.Cache;
+import com.google.common.collect.ListMultimap;
 import com.velocitypowered.api.event.EventTask;
 import com.velocitypowered.api.event.Subscribe;
 import com.velocitypowered.api.event.connection.DisconnectEvent;
@@ -43,15 +45,18 @@ import com.velocitypowered.api.event.connection.PreLoginEvent;
 import com.velocitypowered.api.event.connection.PreLoginEvent.PreLoginComponentResult;
 import com.velocitypowered.api.event.player.GameProfileRequestEvent;
 import com.velocitypowered.api.event.player.ServerConnectedEvent;
+import com.velocitypowered.api.plugin.PluginContainer;
 import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.GameProfile.Property;
+
 import net.kyori.adventure.text.TextComponent;
 import net.kyori.adventure.text.serializer.legacy.LegacyComponentSerializer;
 import org.geysermc.floodgate.api.player.FloodgatePlayer;
 
+import java.lang.reflect.Field;
 import java.net.InetSocketAddress;
 import java.time.Duration;
 import java.util.ArrayList;
@@ -61,6 +66,8 @@ import java.util.UUID;
 
 public class ConnectListener {
 
+    private static final String FLOODGATE_PLUGIN_NAME = "org.geysermc.floodgate.VelocityPlugin";
+
     private final FastLoginVelocity plugin;
     private final AntiBotService antiBotService;
 
@@ -80,6 +87,16 @@ public class ConnectListener {
         InetSocketAddress address = connection.getRemoteAddress();
         plugin.getLog().info("Incoming login request for {} from {}", username, address);
 
+
+        // FloodgateVelocity only sets the correct username in GetProfileRequestEvent, but we need it here too.
+        if (plugin.getFloodgateService() != null) {
+            String floodgateUsername = getFloodgateUsername(preLoginEvent, connection);
+            if (floodgateUsername != null) {
+                plugin.getLog().info("Found player's Floodgate: {}", floodgateUsername);
+                username = floodgateUsername;
+            }
+        }
+
         Action action = antiBotService.onIncomingConnection(address, username);
         switch (action) {
             case Ignore:
@@ -177,4 +194,68 @@ public class ConnectListener {
         Player player = disconnectEvent.getPlayer();
         plugin.getCore().getPendingConfirms().remove(player.getUniqueId());
     }
+
+    /**
+     * Get the Floodgate username from the Floodgate plugin's playerCache using lots of reflections
+     * @param preLoginEvent
+     * @param connection
+     * @return the Floodgate username or null if not found
+     */
+    private String getFloodgateUsername(PreLoginEvent preLoginEvent, InboundConnection connection) {
+        try {
+            // Get Velocity's event manager
+            Object eventManager = plugin.getServer().getEventManager();
+            Field handlerField = eventManager.getClass().getDeclaredField("handlersByType");
+            handlerField.setAccessible(true);
+            @SuppressWarnings("rawtypes")
+            ListMultimap handlersByType = (ListMultimap) handlerField.get(eventManager);
+            handlerField.setAccessible(false);
+
+            // Get all registered PreLoginEvent handlers
+            @SuppressWarnings({ "rawtypes", "unchecked" })
+            List preLoginEventHandlres = handlersByType.get(preLoginEvent.getClass());
+            Field pluginField = preLoginEventHandlres.get(0).getClass().getDeclaredField("plugin");
+            pluginField.setAccessible(true);
+            Object floodgateEventHandlerRegistration = null;
+
+            // Find the Floodgate plugin's PreLoginEvent handler
+            for (Object handler : preLoginEventHandlres) {
+                PluginContainer eventHandlerPlugin = (PluginContainer) pluginField.get(handler);
+                String eventHandlerPluginName = eventHandlerPlugin.getInstance().get().getClass().getName();
+                if (eventHandlerPluginName.equals(FLOODGATE_PLUGIN_NAME)) {
+                    floodgateEventHandlerRegistration = handler;
+                    break;
+                }
+            }
+            pluginField.setAccessible(false);
+            if (floodgateEventHandlerRegistration == null) {
+                return null;
+            }
+
+            // Extract the EventHandler instance from Velocity's internal registration handler storage
+            Field eventHandlerField = floodgateEventHandlerRegistration.getClass().getDeclaredField("instance");
+            eventHandlerField.setAccessible(true);
+            Object floodgateEventHandler = eventHandlerField.get(floodgateEventHandlerRegistration);
+            eventHandlerField.setAccessible(false);
+
+            // Get the Floodgate playerCache field
+            Field playerCacheField = floodgateEventHandler.getClass().getDeclaredField("playerCache");
+            playerCacheField.setAccessible(true);
+            @SuppressWarnings("unchecked")
+            Cache<InboundConnection, FloodgatePlayer> playerCache =
+                (Cache<InboundConnection, FloodgatePlayer>) playerCacheField.get(floodgateEventHandler);
+            playerCacheField.setAccessible(false);
+
+            // Find the FloodgatePlayer instance in playerCache
+            FloodgatePlayer floodgatePlayer = playerCache.getIfPresent(connection);
+            if (floodgatePlayer == null) {
+                return null;
+            }
+            return floodgatePlayer.getCorrectUsername();
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
 }