Ethereal-dev: Re: [Ethereal-dev] ISO 8823 OSI Presentation Protocol

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From: Graeme Lunt <graeme.lunt@xxxxxxxxx>
Date: Tue, 30 Aug 2005 11:31:59 +0200
Hi,

Nice timing.

> I have checked in an asn2eth generated PRES dissector. Please test it.
> Points to check:
>  I'm unsure about the selecton of which PDU type to dissect - works with my
> limited captures.
> Probably ASCE should not be called directly but rather a table of context's
> be built and the next dissector be called based on the information received,
> but this was how it was made in the previous dissector.

I shall try this out as I have found problems with the existing PRES dissector.
It wasn't maintaining the presentation context list at all - which
made it impossible to dispatch on the indirect references. My local
patched version dissected based on the presentation context (abstract
syntax) rather than the association context. This bypassed the ACSE
dissector altogether (when not necessary of course).

Note that my change means you need to register the dissector on the
presentation context, not the association context. I'm not sure, but I
guess that the existing protocol dissectors only use a single
presentation context so there is a one to one mapping with the
association context. X.400 generally uses multiple PCs.

I assume this asn2eth PRES dissector is the preferred way to go now?

I have asn2eth-based RTSE, ROS, X.411 (P1), X.420 (P22) dissectors
which I will submit when I have a verified they work with this new
PRES dissector and the ROS has been verified to work independently of
RTSE (I'm implementing an asn2eth-based X.511 (DAP) for this).

Graeme