Re: CS_SERVERADDR tag is not handled correctly in ct_con_props

On Mon, Jan 6, 2014 at 12:21 PM, Frediano Ziglio <[email protected]> wrote:

> 2014/1/6 Stephen Marshall <[email protected]>:
> > Let me try to explain in better detail:
> >
> > Problem:
> > The CS_SERVERADDR enum is not properly honored in the ct_con_props
> function
> > call.
> > For example, this call should effectively set the host and port for a DB
> > connection, but it results in an error when the connection information is
> > actually used.
> >     ct_con_props( g_connection,
> >                       CS_SET,
> >                       CS_SERVERADDR,
> >                       (CS_VOID*)server,
> >                       CS_NULLTERM,
> >                       (CS_INT*)NULL
> >                     );
> > Here: g_connection is a pointer to type CS_CONNECTION, and server is text
> > of the form "<host> <port>".  Note that FreeTDS provides other ways to
> > specify host and port (e.g. setting the server parameter to
> > "<host>:<port>"; however, the method using CS_SERVERADDR does not work.
> >
>
> Now I got it.
>
> > Approaches to fix:
> > I see two ways to attack this problem.  Of course, you may see others.
> >
> > One approach is to ensure port information is set in the CS_CONNECTION
> data
> > structures and then passed to the other internal data structures used to
> > establish a connection in FreeTDS.  This would be a true fix to the
> > problem, but would require some changes to at least a few internal data
> > structures.
> >
> > Another approach is the mark the CS_SERVERADDR tag as disabled in
> FreeTDS.
> >  This would not actually fix the problem, but would allow client
> > applications to work around the limitation.  However, I think this can be
> > achieved by simply undefining CS_SERVERADDR in cspublic.h.
> >
> > If you have any thoughts on ways to fix this, I'm certainly open to
> > suggestions.
> >
> > Steve
> >
>
> Well, as Sybase write specification while we should stick to it we
> should just handle properly this tag. Perhaps the problem is how to
> fit this with other port specification. Should CS_SERVERADDR port
> override CS_SERVERNAME "host:port" FreeTDS syntax? Perhaps we should
> just document the combination as not supported or undefined behaviour.
>


You raise an interesting idea to use CS_SERVERADDR to set the
CS_SERVERNAME.   This seems easier than either of my suggestions.  The main
complexity is that servername is passed directly to the ct_connect
function, while CS_SERVERADDR is set ahead of time in the CS_CONNECTION
data structure.

I have implemented your suggestion in the attached patch file for
src/ctlib/ct.c.   This required small changes to both ct_con_props and
ct_connect.  I tested this change using sqsh 2.4, but creating a test
within FreeTDS itself would be a good idea.

Let me know if this looks ok to you.   The part where I changed how
not-NULL values of con->server_addr are interpreted in ct_connect is the
only change that may be prone to side effects.  The previous logic appears
to have ignored any server_addr setting that was previously made.  Now
server_addr settings override the server name passed into ct_connect.



> Frediano
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