Ethereal-dev: Re: [ethereal-dev] Multiple Dissectors

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From: Neil Hunter <neil.hunter@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 7 Jul 2000 10:04:37 +0100 (BST)
On Thu, 6 Jul 2000, Ben Fowler wrote:

> WAP is a stack rather than a protocol, thus WSP is carried in WTP a bit like
> TCP is carried in IP. Indeed, I refer to port 9201 data as WSP/WTP.

Hehe - don't you just love definitions ;)
I'd agree that WAP is a protocol stack, but I have to disagree with your
analogy to TCP/IP. In fact WSP is only carried in WTP *if* the session is
connection-oriented. For connection-less mode, WSP is carried raw.

Different phones use different modes (and hence different ports). E.g. the
Nokia 7110's can use either mode, whereas the Ericsson R320 uses
connection-less mode. The differentiator is the port number.

> Inherently a WTP dissector has to arrange for a 'superior' dissector to 
> continue the
> process, just as packet-udp does, otherwise there is no point in starting. 
> I think
> that this goes bit beyond and is more intimate that the relation between
> ppp and payload_ppp, but perhaps we are just saying the same thing in different
> words.

I think we are saying the same thing, but perhaps the place to do it is in the
packet-udp section. I.e. packet-udp hands off connection-mode data to WTP and
connection-less to WSP. WTP processes its data and then passes the remainder
off to WSP. I'm not sure if this level of "chaining" (for want of a better
term) is supported.

> I also think that the dissectors should be kept separate, so although
> I consider this a WAP project and there is a single wap.h header file,
> I have put the code into separate files wsp.c and wtp.c.

Totally agree. This is all related to the WAP Protocol stack - so we'll keep it
together, but modular.

> See my other posts. Thank you for your interest and your very clear
> and helpful comments.

No problem at all, I've got a vested interest in this and I'm keen to give as
well as take!

Cheers,
  Neil

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