prevent partial updates from invalid trailer

by fixing the code order in updateFromDriverSync, moving pure validations first

Author: NexiusTailer

Server/Components/Vehicles/vehicle.cpp

@@ -164,6 +164,13 @@ bool Vehicle::updateFromDriverSync(const VehicleDriverSyncPacket& vehicleSync, I
 		return false;
 	}
 
+	if (vehicleSync.TrailerID && trailer && trailer->getID() != vehicleSync.TrailerID)
+	{
+		// The client instantly jumped from one trailer to another one.  Probably a cheat, so don't
+		// allow it.
+		return false;
+	}
+
 	pos = vehicleSync.Position;
 	rot = vehicleSync.Rotation;
 	velocity = vehicleSync.Velocity;
@@ -218,16 +225,7 @@ bool Vehicle::updateFromDriverSync(const VehicleDriverSyncPacket& vehicleSync, I
 
 	if (vehicleSync.TrailerID)
 	{
-		if (trailer)
-		{
-			if (trailer->getID() != vehicleSync.TrailerID)
-			{
-				// The client instantly jumped from one trailer to another one.  Probably a cheat, so don't
-				// allow it.
-				return false;
-			}
-		}
-		else
+		if (!trailer)
 		{
 			// Got a new one that we didn't know about.
 			trailer = static_cast<Vehicle*>(pool->get(vehicleSync.TrailerID));
@@ -322,19 +320,19 @@ bool Vehicle::updateFromTrailerSync(const VehicleTrailerSyncPacket& trailerSync,
 		return false;
 	}
 
+	PlayerVehicleData* playerData = queryExtension<PlayerVehicleData>(player);
+	if (!playerData)
+	{
+		return false;
+	}
+
 	pos = trailerSync.Position;
 	velocity = trailerSync.Velocity;
 	angularVelocity = trailerSync.TurnVelocity;
 	rot.q = glm::quat(trailerSync.Quat[0], trailerSync.Quat[1], trailerSync.Quat[2], trailerSync.Quat[3]);
 
 	updateOccupied();
 
-	PlayerVehicleData* playerData = queryExtension<PlayerVehicleData>(player);
-	if (!playerData)
-	{
-		return false;
-	}
-
 	Vehicle* vehicle = static_cast<Vehicle*>(playerData->getVehicle());
 
 	if (!vehicle || vehicle->detaching)