End-to-end testing of matchers

[qdeslandes]

More and more matchers are added to bpfilter (15 and counting!), each of them supporting different operators and interacting differently which each BPF flavour (XDP, TC, BPF_NETFILTER, CGroup).

All the matchers are manually tested, but as the number of matchers grows, it's becoming more and more difficult to avoid issues when the code generation logic is modified. Thus, we need an easy-to-use, deterministic way of testing all the matchers.

A solution would be to reuse the logic implemented in the benchmark, minus the numerous iterations of BPF_PROG_TEST_RUN:

• Start the daemon
• Use bfcli to create the filtering chain, using a specific matcher
• Use BPF_PROG_TEST_RUN once and validate the result of the program