Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <2ce68928bcec23a0f41864f4f0fb55f2dd81d739.camel@cyberfiber.eu>
Subject: Re: SIGHUP on connect
From:   "Michael J. Baars" <mjbaars1977.linux-kernel@cyberfiber.eu>
To:     Bernd Petrovitsch <bernd@petrovitsch.priv.at>,
        linux-kernel@vger.kernel.org
Date:   Thu, 29 Oct 2020 15:10:37 +0100
In-Reply-To: <8b693bb1-1711-5289-5bc8-e5955da21968@petrovitsch.priv.at>
References: <0e0db8180bc560c9ebaeb42957cf2ecc365cc80d.camel@cyberfiber.eu>
         <8b693bb1-1711-5289-5bc8-e5955da21968@petrovitsch.priv.at>
Content-Type: multipart/mixed; boundary="=-fAc/fejB8ek2F9WNenpI"
User-Agent: Evolution 3.36.5 (3.36.5-1.fc32) 
MIME-Version: 1.0
Precedence: bulk


--=-fAc/fejB8ek2F9WNenpI
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit

Hi Bernd,

According to manual page socket(7), SO_REUSEADDR allows for local addresses to be reused for binding. I've tested this socket option with the WAN address, it
appears the problem is solved for both local and non-local connections.

I also found the the SO_LINGER socket option to be useful in some way. By default, SO_LINGER is set to 0, so you would think that lingering connections were out
of the question. However, an enabled linger with a l_onoff = 1 and a l_linger = 0 seems to work a lot better than a disabled linger with a l_onoff = 0 and a
l_linger = 0.

Which option would you use?

Mischa.

On Mon, 2020-10-26 at 17:12 +0000, Bernd Petrovitsch wrote:
> Hi all!
> 
> On 25/10/2020 16:11, Michael J. Baars wrote:
> [...]
> > I've been writing a simple client and server for cluster computing this weekend. At first everything appeared to work just fine, but soon enough I found
> > some
> > inexplicable bind errors. I've tried to make sure that the client closes it's sockets before the server closes it's sockets, to prevent linger, but trying
> > did
> 
> Which were exactly?
> English/original text pls ...
> 
> And The close() (and shutdown() syscalls, respectively) don't avoid
> the FIN_WAIT2 timeout on a closed socket.
> Just set the SO_REUSEADDR socket option on the listening socket.
> 
> > not help. Now I think I found the problem.
> 
> Then solve it.
> 
> > Please do have a look at the code. It looks like the SIGHUP is sent to the server not on close or exit, but on the connect instead.
> 
> Too lazy to save and uncompress the file ...
> 
> MfG,
> 	Bernd

--=-fAc/fejB8ek2F9WNenpI
Content-Type: application/x-xz-compressed-tar; name="so_reuseaddr and so_linger.tar.xz"
Content-Disposition: attachment; filename="so_reuseaddr and so_linger.tar.xz"
Content-Transfer-Encoding: base64
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--=-fAc/fejB8ek2F9WNenpI--