Communications software reverse engineering: A semi-automatic approach

A large amount of existing data communications software was developed prior to the advances in software technology using informal and ad hoc techniques. As a result, developers are suffering during the maintenance of this software since the quality of both the software and the associated documentation is not acceptable. Moreover, the addition of features to this software is often leading to side-effects and unexpected interactions. Also, much of this software is missing a clear and formal service definition, or at least a formal statement about their mission. Design documents are either informal or incomplete and do not reflect the existing software, and test plans are either incomplete or not documented. Maintaining and expanding such software becomes unmanageable, very time-consuming and sometimes impossible. In this paper, we propose a reverse engineering method that can be applied to such informally developed communications software to facilitate the extraction of design choices and documentation in addition to the formal definition of the intended communication service. This method obtains a high-level abstraction of the communications software based on Estelle, an International Standardization Organization (ISO) standard specification language for protocols and for distributed systems in general. The application of this reverse engineering process will definitely increase the productivity of the protocol/software engineer. Morover, it will allow the revalidation and redesign of the extracted design and the derivation of more comprehensive test plans. An example is also provided to illustrate the application of the method.