Re: Nsock new engines

[Henri Doreau <henri.doreau () gmail com>]

2012/10/26 David Fifield <david () bamsoftware com>:
> On Thu, Oct 25, 2012 at 03:48:27PM -0500, Kris Katterjohn wrote:
> > On 10/25/2012 02:02 PM, Henri Doreau wrote:
> > > it looks like WSAPoll isn't able to deal with stdin, even though I can't
> > > find anything in the WSAPoll() documentation that would explain this
> > > difference of behavior with select().
> > >
> > > Does anyone know a way to do it? I unfortunately don't, and couldn't find
> > > anything that would work for both stdin options (tty, pipes, files) and
> > > sockets. Since only ncat should be affected there, maybe the patch
> > > attached (untested) would be an acceptable fix? It enforces the use of
> > > the select engine on windows when stdin is a tty. Could you please give
> > > it a try? (also with piping something, like echo, to ncat, and
> > > redirecting a regular file to ncat' stdin).
> >
> > It sounds like you're suggesting that select() works for stdin on Windows
> > but WSAPoll() doesn't.  Is that right?  Although it's gone through some
> > changes over the years, I originally wrote the fselect()[1] in nbase because
> > select() doesn't work with stdin on Windows (and I did it for ncat and
> > nsock).  A simple grep shows that fselect() is called in engine_select.c for
> > nsock instead of the vanilla select().
> >
> > If I'm not misunderstanding what you're saying, then I think WSAPoll() and
> > select() are not that different in their behavior wrt stdin (although I have
> > no experience with WSAPoll afaik).  I don't have a direct suggestion for a
> > fix, but I think it's important to note that there's a workaround for
> > select() and it's not doing "the right thing" with stdin on Windows either.
>
> I think your analysis is correct, Kris. We probably need a similar
> workaround for poll as for select (fpoll?). Henri, let's unconditionally
> use the select engine for Ncat on Windows for now until we have a fix.
>
> David Fifield

Thanks Kris, this makes completely sense. I'll try to implement a
fpoll() at some point, looks like it's the way to go.

For now I've enforced the use of the select engine for ncat on windows
(see r30118).

-- 
Henri
_______________________________________________
Sent through the nmap-dev mailing list
http://cgi.insecure.org/mailman/listinfo/nmap-dev
Archived at http://seclists.org/nmap-dev/