Fix #559: Skip caching key with zero object handle

[bukka]

This is a solution for #559 .

It might happen that the object with zero object handle gets to cache_key which then result in unnecessary failure when caching the key. This skips the key caching if the object handle is 0.

Interestingly after this the handshake became much quicker so it might have some impact on performance as well. I can't say it for sure if it impacts production as I use everything with debug build but it should save some session logins for sure.

Checklist

• Test suite updated with functionality tests
• Test suite updated with negative tests

Reviewer's checklist:

• Any issues marked for closing are addressed
• There is a test suite reasonably covering new functionality or modifications
• This feature/change has adequate documentation added
• Code conform to coding style that today cannot yet be enforced via the check style test
• Commits have short titles and sensible commit messages
• Coverity Scan has run if needed (code PR) and no new defects were found

[bukka]

This will probably need some sort of test so it's just a draft for now.

[simo5]

Minor nits, but otherwise LGTM!

[simo5]

please us CK_INVALID_HANDLE here.

[simo5]

zero -> invalid

[simo5]

Do you have a way to add a test that exercises this code path ?

[bukka]

Do you have a way to add a test that exercises this code path ?

I might be able to get it in some integration test with nginx. This is hopefully the last issue so once I get it all working, I would like to start looking into getting the fixes upstream which means adding the tests for the current patches where possible so will try then.

[bukka]

Interestingly after this change, the skip is not even happening. I have done some experiments and just purely getting the handle before the p11prov_take_login_session session login results in actual handle being returned so it seems there is some reset going on during the session login. Will need to check it out properly. This also speed up the whole thing. I also checked that CopyObject is happening and it's successful so it looks like some flow thing possibly.