Re: Packet direction detection from dissector level

[Jaap Keuter <jaap.keuter () xs4all nl>]

Hi,

There are a few ways to tackle this.
First is based on a known port number. Say the server port has a fixed  
value of 4444, you can check the pinfo to see if the sourceport is  
4444. If so it's a server packet. If its destinationport is 4444 it is  
a client packet. If neither it's not your protocol.

If there's no fixed port, you can use a conversation. This allows you  
to track data trough time, see README.developer for more info.

Tabs vs. spaces. Preferred are spaces.  Next are opening tabs, so only  
at the start of the line. But first and foremost a consistent style is  
important.

Thanks,
Jaap

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On 12 feb 2010, at 02:31, Daniel Kozar <los.danielos () gmail com> wrote:

> Hello,
> I'm attempting to write a dissector of a protocol used by a Polish IM
> system called Gadu-Gadu. It's my first "larger" C project, so please
> don't expect results very soon, but I'll surely try to do my best. So
> far, having read the dissector developer documentation
> (README.developer) and the more general Developer's Guide, I've
> started writing and instantly stumbled upon a problem.
>
> The problem is - is there any way to know if the packet is being sent
> by the client or the server? I've encountered it because every packet
> in this protocol has a "type" field in its header, but some values
> repeat themselves and mean something else when sent by a server and
> something else when sent by a client. I'd be thankful for providing
> any solutions on how to solve this.
>
> Another question - is the indentation/tab-width/"tabs as spaces"
> coding style strictly enforced? Or is it okay to use your own
> (without, obviously, being crazy), preferably with comments from this
> -> http://www.wireshark.org/tools/modelines.html <- included?
>
> Thank you very much in advance,
> D.K.
> ___________________________________________________________________________
 

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