From owner-freebsd-hackers@FreeBSD.ORG  Fri Jan 23 08:01:20 2004
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 8A4C216A4CE; Fri, 23 Jan 2004 08:01:20 -0800 (PST)
Received: from smtp2.enst.fr (reloaded.enst.fr [137.194.2.14])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 96A4C43D66; Fri, 23 Jan 2004 08:00:44 -0800 (PST)
	(envelope-from pook@enst.fr)
Received: from email.enst.fr (muse.enst.fr [137.194.2.33])
	by smtp2.enst.fr (Postfix) with ESMTP
	id 02290463; Fri, 23 Jan 2004 17:00:42 +0100 (CET)
Received: from roo (roo-ether.enst.fr [137.194.160.54])
	by email.enst.fr (8.9.3/8.9.3) with ESMTP id RAA26213;
	Fri, 23 Jan 2004 17:00:42 +0100 (CET)
Received: from pook (helo=roo)
	by roo with local-esmtp (Exim 3.36 #1 (Debian))
	id 1Ak3jf-0006tv-00; Fri, 23 Jan 2004 17:00:43 +0100
To: Andre Oppermann <andre@freebsd.org>
From: Stuart Pook <Stuart.Pook@infres.enst.fr>
Organisation: Ecole Nationale Superieure des Telecommunications, Paris, France
In-reply-to: Message from andre@freebsd.org of Fri, 23 Jan 2004 16:50:33
	+0100.	<401142C9.70502@freebsd.org> 
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
Date: Fri, 23 Jan 2004 17:00:43 +0100
Message-Id: <E1Ak3jf-0006tv-00@roo>
Sender: Stuart Pook <pook@enst.fr>
cc: freebsd-hackers@freebsd.org
Subject: Re: send(2) does not block, send(2) man page wrong? 
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 23 Jan 2004 16:01:20 -0000

> send() for UDP should block if the socket is filled and the interface
> can't drain the data fast enough.

It doesn't (at least I cannot make it block)

> Good question.  There is not feedback loop like in tcp, so handling this
> blocking and releasing would be a little bit harder to do for UDP.

Send(2) indicates that it should do so.

> > I have written a test program,
> > http://www.infres.enst.fr/~pook/send/server.c, that shows that send does
> > not block on FreeBSD.  It does with Linux and Solaris.
> 
> Do you know what the behaviour of Net- and/or OpenBSD is?

NetBSD is the same as FreeBSD.  I have not tested OpenBSD.
MacOS X is similiar to FreeBSD in that send doesn't block, howver
the send does not give an error: the packet is just thrown away.

Stuart