Traffic diversity and code coverage: a preliminary analysis

It is generally assumed that using more diverse traffic to test network devices could achieve larger code coverage. However, how to describe the diversity of traffic traces and the relationship between the traffic diversity and code coverage is still an issue. In this paper, the traffic diversity is defined using the number of packets and the size of the subnets involved, and traces having various diversity are used to evaluate the corresponding code coverage for the programs in a network device. Experiment results show that more number of packets or larger size of network segments can generate larger diversity indices and thus larger code coverage. For Snort, as the number of packets increases from 1 to 10,000,000, representative diversity index and the code coverage can increase from 0 to 0.95 on the basis of Simpson's index and from 19.1% to 32.2%, respectively. As the size of network segments increases, representative diversity index and the code coverage can increase from 0.41 to 0.82 and from 28.2% to 32.2%, respectively. Similar results can be obtained in the case of Linux kernel. If the mappings among different diversity indices and the corresponding code coverage can be built beforehand, the quality of the tests can improved. Copyright © 2014 John Wiley & Sons, Ltd.