IPv6 and commit d882add695bbd5ea03961c08ac2c0380fbf2947b

[Jeremy Allison]

On Tue, Sep 20, 2022 at 09:20:04PM -0700, Jeremy Allison via samba-technical wrote:
>On Tue, Sep 20, 2022 at 10:53:04PM -0400, Nathaniel W. Turner wrote:
>>  Hi Jeremy,
>>    On Fri, Sep 16, 2022 at 01:33:26PM -0700, Jeremy Allison via
>>    This is internal to discover_dc_dns(), so you
>>    could probably add an extra flag here to tell
>>    discover_dc_dns() to return IPv6-only, and
>>    have it skip that DC if it doesn't have an
>>    IPv6 address returned.
>>
>>  Thanks for taking a look at this! I'll work on a patch. 
>>  What's the right behavior here? In the case where the local server has no
>>  routable IPv6 addresses (e.g. link local IPv6 addresses only), we might
>>  infer that we're only interested in IPv4 addresses for the DC, and vice
>>  versa.
>>  If we don't have easy access to the set of local addresses in this code
>>  path, a simpler alternative might be to pick up to 1 IPv4 address and up
>>  to 1 IPv6 address, and potentially try them both. If the test connection
>>  fails quickly in the case of an unusable address, this might be OK.
>>  Thoughts?
>
>Change the API for dsgetdcname() so the caller
>can specify if they want IPv6 or IPv4. Don't
>return more than one address - we don't want
>to double the lookup time for a down-DC.

Probably should be a 'bool ip_v6_only' parameter.
Only set it if the client has only IPv6 addresses
available.