Wireshark-dev: Re: [Wireshark-dev] Dissectors for SMS over GPRS-LLC
From: "Cyrille Colin" <[email protected]>
Date: Mon, 20 Aug 2007 13:09:21 +0100
Title: Dissectors for SMS over GPRS-LLC
thanks for your quick replies.
 
going forward on the topic:
my mistake --> actually SMS-CP is completely decoded within DTAP dissector. So a simple modification is needed in packet-gsm_a.c to link GPRS-LLC SAPI 7 with DTAP dissector, and it works fine.
 
I'm submitting a one line patch :) in Bug #1754.
 
I can send a sample pcap for validation, let me know to whom.
 
rgds
Cyrille
 


De : [email protected] [mailto:[email protected]] De la part de Anders Broman (AL/EAB)
Envoyé : jeudi 16 août 2007 18:05
À : Developer support list for Wireshark
Objet : Re: [Wireshark-dev] Dissectors for SMS over GPRS-LLC

Hi,
I think you are right and a start could be to separate out the SMS parts then. I'm busy on other stuff right now so I'm not able to take it on
.
An Idea might be to discuss the interfaces and decide how we'd want it to look and what names to use ,there is a lot of interconection between
the GSM/UMTS dissectors at the moment and probably duplicated code.
Regards
Anders


From: [email protected] [mailto:[email protected]] On Behalf Of Neil Piercy
Sent: den 16 augusti 2007 17:57
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] Dissectors for SMS over GPRS-LLC

IMHO the gsm_a is really about four protocol dissectors which are too inter-mixed in the one huge file, and should really all be in separate files and with "proper" wireshark linkage between them. The clue is in the name: it contais the set of protocols carried over the A interface, not one protocol.
 
I'd support (and might be able to help with) such a separation.
 
Neil


From: [email protected] [mailto:[email protected]] On Behalf Of Anders Broman (AL/EAB)
Sent: 16 August 2007 16:03
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] Dissectors for SMS over GPRS-LLC

Hi,
>some SMS Control Protocol (SMS CP) fields are included in GSM A DTAP dissector, but not the whole protocol.
Should all SMS-CP dissection be done by the new dissector or perhaps the code moved into packet-gsm_a.c ?
Regards
Anders


From: [email protected] [mailto:[email protected]] On Behalf Of Cyrille Colin
Sent: den 16 augusti 2007 16:10
To: [email protected]
Subject: [Wireshark-dev] Dissectors for SMS over GPRS-LLC

Hi

SMS msg can be carried over packet switched GPRS, and I am trying to have Wireshark decode SMS carried on GPRS LLC protocol (SAPI 7).

The stack is the following:

  -------------------
 | sms msg     |               
  -------------------
 | sms T-PDU  |         --> dissector exists (gsm_sms) in packet-gsm_sms.c
  -------------------
 | sms RP       |               --> dissector exists (gsm_a_rp) in packet-gsm_a.c
  -------------------
 | sms CP       |              
  -------------------
 | GPRS LLC   |         --> dissector exists  (gprs-llc) in packet-gprs-llc.c
  -------------------

some SMS Control Protocol (SMS CP) fields are included in GSM A DTAP dissector, but not the whole protocol.

So I basically wrote a small plugin for SMS CP -following the dev guidelines-, and linked to GPRS-LLC and SMS-RP and it works fine.


The questions are:
- is there any interest in having this submitted back to the Wireshark source ?
- if it is the case, what is the best practice (plugin, native) and recommendations for the dissector calls - restrain the calls to be within the new protocol code, or rather use call_dissector() etc in other dissectors, which implies a small diff on other dissectors too.


Thks, and btw I found the developper doc extremely useful -many thks to the author(s).

Cyrille