ip.access BTS IML dissector for wireshark

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Jai Menon jmenon86 at gmail.com
Mon Dec 7 18:41:05 UTC 2009


Hi Harald,

On Sun, Dec 06, 2009 at 12:29:40PM +0530, Harald Welte wrote:
> Dear Jai,
> 
> thanks for your work.
> 
> On Fri, Dec 04, 2009 at 05:10:00PM +0530, Jai Menon wrote:
> 
> > Attached is a direct port of the IML dissector code from the ip.access
> > code to wireshark SVN head with a few changes to make it work with the
> > current API. This was done as part of Harald's GSM workout during
> > FOSS.IN and he suggested I post it to this list. I haven't really
> > tested this code since I dont have access to IML traces, but assuming
> > the original code worked, this one should too.
> 
> Great.  Anyone who has two nanoBTS can set up a multi-TRX BTS and
> trace the IML protocol between those two BTS.  This pcap should be possible
> to decode using this dissector.

Also, if someone could upload/post the resulting pcap, that would be
useful for local testing.

> Before we can submit this mainline, we need to clean up packet-gsm.h though.
> 
> ip.access has one header file (packet-gsm.h) where they define many aspects of
> various different GSM protocols.  This is not really how things are done
> in upstream wireshark.
> 
> Thus, we need to remove everything that is not IML related, like

[...]

> etc. I could now continue for the whole file, but I think you
> get what I mean :)

Indeed :) the first attempt was quite naive as in I wanted to just get it
to build cleanly with the new API.

> Would you be able to clean this further up and do another round of patch
> submission? Thanks again for your help.

Sure thing. Before I go ahead and do that, I wanted to know whats the
preferred approach here. The packet-gsm_ipa dissector code, for
example, doesn't #include any additional headers. Should the iml code
be modified so that all typedefs like ie_def_t are present in the one
source file? Or should the packet-gsm.h header be trimmed down to
contain only what the iml code requires? If it is cleaned up to remove
unused stuff, should the name then be changed to packet-gsm_iml.h or
something similar?

Thanks for the comments.

-- 
Jai Menon





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