Re: ai_flags in calls to getaddrinfo, broader call for reproducibility check

[Robert Pluim <rpluim@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Robin Tarsiger <rtt@dasyatidae.com>
>> Cc: emacs-devel@gnu.org
>> Date: Mon, 11 Jan 2021 04:47:11 -0600
>> 
>> > Note the difference in he.net resolution with and without the 'ipv6
>> > argument, and also the behavior of ipv6.google.com with the ipv6
>> > argument.  Interesting, no?
>> 
>> Definitely. The behavior of "he.net" with 'ipv6 in the former group
>> is something I think of as to be avoided, per elsethread, but this
>> shows the latter truncation for nil more concretely, of course...
>> and the error-swapping behavior with "ipv6.google.com" is bizarre
>> and hard to reconcile with earlier observations, especially the
>> nil-family case. I wonder whether that changes with 'ipv4?
>
> No, it behaves as expected.
>
>> Your ipconfig result showed no "real" IPv6 connectivity
>
> How did you see this?  Would it be possible to deduce that from the
> output of, say, network-interface-list?
>

You only have fe80 and fec0 addresses listed, which are link-local and
site-local prefixes (and the latter has been deprecated so long itʼs
old enough to drink beer in Belgium)

The only assigned globally routable IPv6 prefix is currently 2000::/3,
so we could check for that via network-interface-list.

> I'm asking because I'm still bothered by failures in those two tests,
> and would like to avoid that.  I think it's bad if a test fails when
> there's nothing wrong with Emacs; we should try to skip such tests
> when we know their results cannot be trusted.

The results can be trusted. However, the assumption of the tests is
that DNS lookups on AAAA records will work, and return results for
google.com, which is not the case for you. If you prefer we can change
the tests to check for "no error" rather than 'returns a result' (is
there an ERT 'should-not-error' clause)?

Robert