Use reserved port only when required for NIS look-ups

[Jeff Law]

On 08/13/2012 06:27 AM, Honza Horak wrote:
> On 08/13/2012 01:57 PM, Tomas Mraz wrote:
>  > Also I think that the real reason why the privileged port is used
>  > for all lookups in the current glibc is that the information which
>  > database is secured and which not is not available from the server
>  > and making it necessity to configure this information explicitly on
>  > all clients was considered as user unfriendly. Would it be possible
>  > to make the code do some heuristics and fallbacks? For example for
>  > the shadow and gshadow db default with privileged port and for the
>  > rest default as non-privileged and if the server returns failure try
>  > to use the privileged port?
>
> I think that would be possible if we accepted slightly worse performance
> because of the second request, but generally I like that idea.
Seems reasonable to me as well.  I'd be slightly worried about the 
performance aspects too.

Presumably we could note when the first lookup using a non-privileged 
port failed and for that map & server, use the fallback of a privileged 
port for all future lookups.

Jeff