Use an unresolved APNs hostname to improve GOAWAY handling

[aleksandr-lapushkin]

As discussed in: Connection Refused to APNs

As a small update to the discussion: I did some extra debugging and was able to verify that upon re-establishing the connection to APNs after a GOAWAY is received the IP remains the same. This PR aims to fix that issue.

I was also able to verify that with the fix in place, the IP indeed does change after we reconnect following a GOAWAY.

[jmason]

makes sense to me, 👍

[jchambers]

Thanks!

[aleksandr-lapushkin]

Just as an update: we've been using our fork with this change for at least a week now in production. No connection errors of the kind that we observed earlier have appeared during this timeframe. Thus I'd say this was just what we needed.
Also, @jchambers, I'm guessing this will get merged by someone other than myself (for obvious reasons)?

[jchambers]

Also, @jchambers, I'm guessing this will get merged by someone other than myself (for obvious reasons)?

Yes. Putting out a new release is on my to-do list, but I still need to resolve some other (non-Pushy) priorities first.

[aleksandr-lapushkin]

Got it. thanks.

[jchambers]

@aleksandr-lapushkin we just released Pushy 0.12, which includes this fix. Thanks again for the contribution!