Investigate flaky test test-dgram-broadcast-multi-process

[joaocgreis]

Examples of failures:

• pi1-raspbian-wheezy
• freebsd101-32
• freebsd101-64

[joaocgreis]

It seems that this test always fails on the platforms where it fails, and always passes where it passes.

[jbergstroem]

The problem (at least on freebsd) is that it doesn't exit properly, making multiple other tests binding to 127.0.0.1:12346 fail.

Edit: s/problem/result of the problem/ to be clear.

[Trott]

FWIW, I believe this was fixed on the Raspberry Pi by #2808.

As for the FreeBSD issue:

• It seems that the FreeBSD machines on CI don't treat 255.255.255.255 as a broadcast address or don't allow the node process access to that IP address via UDP. Is that even possible?
• I believe this is the last issue before the tests in test/internet are all working and not flaky, which means that if we wanted to integrate them into CI, we could. (I believe the last time this came up, there were concerns about TLS tests hitting actual hosts on the Internet frequently enough to be bad net citizens. So there are other perhaps issues to address.)

[jbergstroem]

@Trott: broadcast is set to something different because the runners inside a jail (we treat localhost slightly different as a result as well) -- 255.255.255.255 isn't reachable.

Do we perhaps want to pass broadcast address to the suite in a similar fashion as localhost?

[Trott]

@jbergstroem: Sounds like an idea worth trying to me. Alternative possibility if adding another environment variable to the FreeBSD config is frowned upon: If in a FreeBSD jail, get broadcast address by running ifconfig and grabbing the IP address that appears right after a case-sensitive match on broadcast.

[jbergstroem]

@Trott jails are a bit special (some default values are routed 'magically'), so the granularity of passing through ENV is preferrable imo. I can PR.

[Trott]

@jbergstroem 👍

[jbergstroem]

@Trott I'll update the freebsd buildbots to pass proper broadcast -- want me to file a new PR with above commit or is it perhaps part of something else I'm missing?

[Trott]

@jbergstroem New PR works for me. Thanks!