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

[Robin Tarsiger <rtt@dasyatidae.com>]

Robert Pluim wrote:
>> There is no _reliable_ way I know of to determine this programmatically,
>> certainly not without sending some probe queries with a high level of
>> specific control over them, and I expect that would be a rather hairy
>> thing to do just for a few tests, and not reasonably maintainable.
> 
> (require 'dns)
> (skip-unless (dns-query "google.com" 'AAAA))

Oh, wow, there's _already_ a dns.el in core? Huh. Well, that obviates
my primary concerns about doing direct DNS probes, provided it works
and is a reasonable thing to load for the test suite otherwise...

> and then do the network-lookup-address-info tests (although on Windows
> this depends on DNS over TCP working,

Ergh. I just checked with `dig +tcp` against my crappy ISP CPE and it
rejects the connection, which seems like anecdata toward that failing
in a lot of configurations.

Do you happen to know OTTOYH _why_ datagram sockets aren't supported
in Emacs on Windows to start with... ?

> and either /etc/resolv.conf or a
> working nslookup).
The latter should at least be stock on Windows AFAIK. I'd forgotten that
it shows the list of resolver addresses too.

-RTT