Verification request timeouts

[dbkr]

Looks like verification requests just don't time out on android

[dbkr]

In fact even web doesn't time them out when sending them (I can accept a verification request on android 2 minutes after sending one on web, and web is still waiting and responses once I do).

Do we want timeouts at all? I think yes: verifications are interactive like calls, they should only notify if they're timely.

[dbkr]

The most useful things to do first would be to:

1. Ignore any verification requests that arrive after a timeout (2 minutes, probably), and
2. Make sure verification requests aren't displayed if a cancellation arrives immediately afterwards.

1 is subtle because to be done properly it need to use the age parameter on the event to get a good estimate of the event age. iOS uses a longer timeout because it just looks at the originserver TS I think, but 2 mins should be sufficient if we use age correctly.

I was reproducing verification banners getting stuck after cancelled requests, but after trying to implement a fix I couldn't then repro the failure without the fix.

[JanZerebecki]

From the few verifications I did, only having the option for it being synchronous (UI wise) and with a timeout created problems in different situations:

• I can't request it, compare it over an existing secure channel like GnuPG signatures and once I get a reply, go back to element to confirm as I'm just too slow. Ideally here allowing even month between steps would be preferable.
• Chaining from other Web of Trust systems, like https://metacode.biz/openpgp/proofs , thus this relates to Support transitive trust for E2E verification between users (i.e. web-of-trust) in some situations matrix-org/matrix-spec#433
• When network connectivity is slow or/and intermittent it will time out before we can view the verification code.
• I fat finger it and accidentally cancel. Now I need to start over, needing to wait again, start comparing. Instead of being able to correct my mistake and continue the comparison from where I was interrupted.

I see no good reason for a timeout if the UI is done inline in the chat.