Re: [bug-inetutils] bug found in inetutils-1.5 telnet binary

[Edward Attfield]

       Thanks.
 
 I realised a short while after sending my bug report that I should have
sent some diff, too, to make it easier to figure out. Thanks for ploughing
through the larger file.
 
 My favorite thought about this bug is that it is present in most of the
telnet flavours, and has been there for at least thirty years.
 
 Ed 
 
 
 Debarshi Ray wrote:
 
>   
> >      
> >  I have attached a small manyfd.c program that invokes telnet to show the
> > problem, and I have attached a better version of sys_bsd.c.
> >
> >  The revised sys_bsd.c adds an integer "nfds" and sets it while using
> > FD_SET, so that select() can be called this way
> >
> >   select(nfds+1, &ibits, &obits, &xbits, &TimeValue)
> >    
>    
>
> Since the attached sys_bsd.c did not produce a clear 'diff' neither
> against the 1.5 version or the current copy in CVS, I tried to
> visually pick and apply your changes against the file in CVS. That
> seems to boil down to:
>
> Index: telnet/sys_bsd.c
> ===================================================================
> RCS file: /sources/inetutils/inetutils/telnet/sys_bsd.c,v
> retrieving revision 1.14
> diff -u -p -r1.14 sys_bsd.c
> --- telnet/sys_bsd.c	4 Jun 2007 17:27:01 -0000	1.14
> +++ telnet/sys_bsd.c	14 Apr 2008 11:03:49 -0000
> @@ -1062,42 +1062,57 @@ process_rings (int netin, int netout, in
>     */
>    int returnValue = 0;
>    static struct timeval TimeValue = { 0 };
> +  int nfds = 0;
>
>    if (netout)
>      {
>        FD_SET (net, &obits);
> +      if (net > nfds)
> +        nfds = net;
>      }
>    if (ttyout)
>      {
>        FD_SET (tout, &obits);
> +      if (tout > nfds)
> +        nfds = tout;
>      }
>  #if defined(TN3270)
>    if (ttyin)
>      {
>        FD_SET (tin, &ibits);
> +      if (tin > nfds)
> +        nfds = tin;
>      }
>  #else /* defined(TN3270) */
>    if (ttyin)
>      {
>        FD_SET (tin, &ibits);
> +      if (tin > nfds)
> +        nfds = tin;
>      }
>  #endif /* defined(TN3270) */
>  #if defined(TN3270)
>    if (netin)
>      {
>        FD_SET (net, &ibits);
> +      if (net > nfds)
> +        nfds = net;
>      }
>  #else /* !defined(TN3270) */
>    if (netin)
>      {
>        FD_SET (net, &ibits);
> +      if (net > nfds)
> +        nfds = net;
>      }
>  #endif /* !defined(TN3270) */
>    if (netex)
>      {
>        FD_SET (net, &xbits);
> +      if (net > nfds)
> +        nfds = net;
>      }
> -  if ((c = select (16, &ibits, &obits, &xbits,
> +  if ((c = select (nfds+1, &ibits, &obits, &xbits,
>  		   (poll == 0) ? (struct timeval *) 0 : &TimeValue)) < 0)
>      {
>        if (c == -1)
>
> Also available at http://rishi.fedorapeople.org/gnu/telnet-select.diff
>
> Applying it fixed the issue for me. Thank you Edward. :-)
>
> Happy hacking,
> Debarshi
>