From: ovs-dev-boun...@openvswitch.org <ovs-dev-boun...@openvswitch.org> on 
behalf of Lance Richardson <lrich...@redhat.com>
Sent: Tuesday, August 8, 2017 11:59 AM
To: Ben Pfaff
Cc: d...@openvswitch.org
Subject: Re: [ovs-dev] DNS support options

> From: "Ben Pfaff" <b...@ovn.org>
> To: d...@openvswitch.org
> Sent: Tuesday, August 8, 2017 2:43:17 PM
> Subject: [ovs-dev] DNS support options
> Open vSwitch currently supports only IP addresses for specifying
> OpenFlow and OVSDB remotes.  It would be nice to support DNS names.
> Open vSwitch can't afford to let DNS resolution block processing, so it
> needs some way to resolve DNS asynchronously.  I've come up with the
> following solutions so far:
>         * Implement it ourselves using threads.  Probably, this would be
>           a single worker thread that loops through calls to
>           getaddrinfo().
>         * glibc has getaddrinfo_a(), an asynchronous version of
>           getaddrinfo().  *BSD and Windows do not have this function, so
>           we would still need to implement it ourselves (probably using
>           threads) if we adopted this approach, so it might be more work
>           than the first solution.
>         * Use an external asynchronous DNS library.  GNU adns looks like
>           a good choice
x------------- cut ----------------x
>           It has a port to Windows but I don't know whether it's
>           up-to-date.

Windows has its own APIs for DNS name resolution:
DnsQueryEx() which is asynchronous: 
DnsQuery() which is synchronous: 

So we could use either of those. 

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