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Date: Wed, 2 May 2001 18:44:35 +0200
From: Corinna Vinschen <cygwin-apps AT cygwin DOT com>
To: cygapp <cygwin-apps AT cygwin DOT com>
Subject: Re: rshd uses pipes to communicate with shell
Message-ID: <20010502184435.C9762@cygbert.vinschen.de>
Mail-Followup-To: cygapp <cygwin-apps AT cygwin DOT com>
References: <13043917449 DOT 20010428233534 AT logos-m DOT ru> <20010429220820 DOT E22095 AT cygbert DOT vinschen DOT de> <310163284 DOT 20010430201528 AT logos-m DOT ru>
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In-Reply-To: <310163284.20010430201528@logos-m.ru>; from deo@logos-m.ru on Mon, Apr 30, 2001 at 08:15:28PM +0400

On Mon, Apr 30, 2001 at 08:15:28PM +0400, egor duda wrote:
> Hi!
> 
> Monday, 30 April, 2001 Corinna Vinschen cygwin-apps AT cygwin DOT com wrote:
> 
> CV> On Sat, Apr 28, 2001 at 11:35:34PM +0400, egor duda wrote:
> >> Hi!
> >> 
> >>   is there some special reason for using pipes in rshd? this breaks
> >> programs that rely on getpeername() for additional security check when
> >> they're called from rshd.
> 
> CV> It's the base implementation. I didn't change anything except for
> CV> getting it working. Feel free to change it but be aware of that
> CV> annoying socketpair problem some users have. Just in case...
> 
> oh, i see. i should make myself clearer.  i'm talking about
> 
> #ifdef __CYGWIN__
>         int cv[2];
> #endif
> 
> in rshd.c. base implementation uses pipe to handle stderr, but cygwin
> version seems to handle stdout via pipe too. if some program started
> by rshd then calls getpeername (1, &name, &name_len), it fails with
> ENOTSOCK. i suspect there was some reason for adding 'cv', wasn't
> there?

Sure. I'm actually not quite sure what the exact reason was but
somehow I needed it when I patched it a year ago. AFAIR, I once got
"Descriptor is a file, not a socket" messages and using that additional
pipe solved it.

While we're talking about that... this reminds me evidently of the
USE_PIPES problem in OpenSSH that some people have. I wouldn't be
surprised if the reason is the same...

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin AT cygwin DOT com
Red Hat, Inc.