Goal

Prevent potential timeout in unit tests

Why

The for loops in s2n_security_policy_get_version() and s2n_security_policy_supports_tls13() use uint8_t i = 0, which can only hold values from 0 to 255. Currently, s2n-tls has only 140 security policies, so everything is fine. However, as we add more policies in the future, the number of policies will eventually exceed the range of uint8_t.

Additionally, some unit tests define their own testing policies that do not exist in the security_policy_selection array. In this case, the only way to exit these for loops is to hit the security_policy_selection[i].version == NULL condition (i.e. the last element in security_policy_selection). If the last policy with version = NULL is out of range, these two for loops will become infinite and lead to timeout failure.

How

Replace uint8_t with another date type of a larger range like size_t

Testing

I found timeout failure in 25 s2n-tls unit tests by creating 120 copies of the test_all policy and exceeding the uint8_t range. After applying the fix in this PR, all the timeout failures went away.

I don't think our CI jobs enable the --timeout flag, so I only ran the testing locally via

CTEST_PARALLEL_LEVEL=$(nproc) ctest --test-dir build --timeout 120

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.