FreeTDS Development Group

["James K. Lowden" <jklowden AT freetds.org>]

On Tue, 15 Jan 2013 15:10:04 +0000
Tony Esposito <Tony.Esposito AT region10.org> wrote:

> Why is osql even bothering to do a reverse DNS lookup of an IP
> address?  If you do not use or have DNS this is going to fail yet it
> does not help me determine if my FreeTDS or ODBC is configured
> correctly.  

It shouldn't fail.  It now prints a warning, as intended.  

Failed reverse-lookup produces a warning because most addresses indeed
do have names.  We know that because osql has been part of FreeTDS for
several years and this was the first reported reverse-lookup bug.  

As a practical matter, osql locates a host "name" that can't be
verified within the confines of the machine.  It may parse correctly,
but there's no way to know if it represents a valid address without
involving the network.  Successful DNS lookup is necessary for a name.
For an address, successful reverse lookup indicates a valid address,
and the looked-up name may confirm to the person reading the output
that that's the intended machine.  

It's certainly debatable where osql should end its verification.  For
example, it could ping the address.  My sense is that osql has done its
job if the configuration files have yielded a valid address for the
provided DSN.  

> or at least make it a command-line option 

One of the reasons osql was written as a shell script was to facilitate
self-diagnosis and self-repair.   

--jkl