linux-kernel - Re: NCPFS and brittle connections

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Message-ID: <45B7D750.1040501@drzeus.cx>
Date:	Wed, 24 Jan 2007 23:01:52 +0100
From:	Pierre Ossman <drzeus-list@...eus.cx>
To:	Petr Vandrovec <vandrove@...cvut.cz>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: NCPFS and brittle connections

Petr Vandrovec wrote:
>
> Hello,
>   create test scenario where first transmit of NCP request is lost by
> network, and before resend you kill this process.  So it stops
> resending, but local sequence count is already incremented.  Then when
> next process tries to access ncpfs, server will ignore its requests as
> it expects packet with sequence X, while packet with sequence X+1
> arrived.

Figured something along those lines, but I couldn't find any docs on the
protocol so I wasn't sure. You wouldn't happen to have any pointers to
such docs?

>
> And unfortunately it is not possible to simple not increment sequence
> number unless you get reply - when server receives two packets with
> same sequence number, it simple resends answer it gave to first
> request, without looking at request's body at all.  So in this case
> server would answer, but would gave you bogus answer.
>

This sounds promising though. In that case it wouldn't be necessary to
store the entire request, just the sequence number, right?

Rgds

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

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