add file interface

include/sp/io/IOInterface.h

@@ -74,6 +74,9 @@ void IOStream<IOTag, MessageDispatcher, MessageFactory>::RecieveMessages() {
 				throw std::runtime_error("VarInt is too big");
 		}
 
+		// nothing to read
+		if (lenghtValue == 0)
+			return;
 
 		DataBuffer buffer;
 		buffer = m_Interface.Read(lenghtValue);