Detecting Protocol Errors Using Particle Swarm Optimization with Java Pathfinder

Network protocols are critical software that must be verified in order to ensure that they fulfil the requirements. This verification can be performed using model checking, which is a fully automatic technique for checking concurrent software properties in which the states of a concurrent system are explored in an explicit or implicit way. However, the state explosion problem limits the size of the models that are possible to check. Particle Swarm Optimization (PSO) is a metaheuristic technique that has obtained good results in optimization problems in which exhaustive techniques fail due to the size of the search space. Unlike exact techniques, metaheuristic techniques can not be used to verify that a program satisfies a given property, but they can find errors on the software using a lower amount of resources than exact techniques. In this paper, we propose the application of PSO to solve the problem of finding safety errors in network protocols. We implemented our ideas in the Java Pathfinder (JPF) model checker to validate them and present our results. To the best of our knowledge, this is the first time that PSO is used to find errors in concurrent systems. The results show that PSO is able to find errors in protocols in which some traditional exhaustive techniques fail due to memory constraints. In addition, the lengths of the error trails obtained by PSO are shorter (better quality) than the ones obtained by the exhaustive algorithms.