Re: NCPFS and brittle connections

From: Pierre Ossman
Date: Wed Jan 24 2007 - 17:02:18 EST


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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