res_pjsip_stir_shaken: Use correct Caller ID to lookup certificate.

[seanbright]

Determine the Caller ID to use for certificate lookup based on the same logic we use when setting up the INVITE session. This allows Caller ID set via the CALLERID() function to be used for STIR/SHAKEN certificate lookup.

Resolves: #46

[gtjoseph]

cherry-pick-to: 18
cherry-pick-to: 20
cherry-pick-to: certified/18.9

[gtjoseph]

Given all the test failures, what's the path forward for this PR?

[trinicomcom]

Hi guys, not sure if I am helping here but been trying to get asterisk to send S/S identity header for a week now.
I found another issue with the stir shaken identity header that is created by asterisk to send out is that the To Caller ID is also the Orig Caller ID in the identity header. I am pretty sure all we need is to put the $callerid(num) from extensions.conf for outbound calls in the origin in the header creation and just send that for all outbound calls and not try to match a cert to a caller ID number since all we are doing is sending out a master cert for the owner of all the numbers in the switch to prove the outbound call is legit and the owner is certified. I hope this makes sense. I can help test any releases if you want I would just need some direction on how to compile it on my lab server.

[jcolp]

@seanbright Is this now good to review again?

[seanbright]

It’s ready to be reviewed. Was I the hold up? There are failing tests that need to be fixed but I do not personally plan on fixing them.

[jcolp]

No, I just didn't know what the actual state of things were currently.

[seanbright]

Given all the test failures, what's the path forward for this PR?

You can do one of the following:

1. Fix the tests
2. Disable the tests

This simple patch has been sitting for 2 years (originally published to gerrit 7/21) waiting to be committed.