Fix CodeQL Findings 2022-12-23

[pepoluan]

What do these changes do?

Fix some more significant CodeQL warnings, i.e., those that can't be dismissed outright.

Are there changes in behavior for the user?

None

Related issue number

Closes #343 , #344 , #345 , #346, #349, #350, #351

Checklist

• [x] I think the code is well written
• [x] Unit tests for the changes exist

[codecov[bot]]

Codecov Report

Merging #348 (6ca44e9) into master (fea5c0c) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #348   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines         1696      1696           
  Branches       310       310           
=========================================
  Hits          1696      1696           

Impacted Files	Coverage Δ
aiosmtpd/proxy_protocol.py	100.00% <ø> (ø)
aiosmtpd/controller.py	100.00% <100.00%> (ø)
aiosmtpd/smtp.py	100.00% <100.00%> (ø)

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more

[pepoluan]

Don't you hate intermittent test failures... I'm barging on because the test failures are really intermittent. I mean, like one OS with one particular Python version fails, while ALL others succeeds. Then the next iteration a different combination fails... with no rhyme nor reason.

Luckily our GHCI workflows have been designed so it would be an easy -- and quite fast -- task to just rerun the failed tests. But I'm delaying that until this series of commits and pushes are done.

[pepoluan]

When merged, this PR fixes all outstanding CodeQL warnings (those that I haven't dismissed outright) except one. That one requires some deeper thought as it's a decorator and things get reeeeeallly hairy there...

No real urgency, as without the fixes aiosmtpd actually Just Works. But it's good to see no outstanding "security" item in the Security tab 😄

[pepoluan]

Adding @warsaw here because there are changes that applies to his code 😉

[warsaw]

Apologies for the delayed response. Thanks for merging this one!