Re: [Wireshark-commits] rev 36659: / /trunk/epan/dissectors/: Makefile.common packet-rohc.c

[Martin Mathieson <martin.r.mathieson () googlemail com>]

On Sat, Apr 16, 2011 at 1:38 PM, Anders Broman <a.broman () bredband net>wrote:

>  Martin Mathieson skrev 2011-04-16 14:03:
>
> Hi Anders,
> There is already most of the ROHC profile in packet-pdcp-lte.c.  I'd been
> meaning to separate it out so that it could be used from other places (e.g.
> when I create UMTS PDCP...)
>
> Martin
>
> I missed that, how to proceed? I think the ROHC code should live in a
> separate file I have a trace
> with Ethertype ROHC for instance.
> Regards
> Anders
ROHC should definitely be in a separate file, which I hadn't got around to
doing.  My code was mostly written around 3 years ago, but to be honest
hasn't been used much.

My implementation needs a few hints to decode the ROHC frame. Here are the
ROHC fields in packet-pdcp-lte.h - they are what my company's decoder needs
to have supplied to it.



/* RoHC settings */  83 gboolean rohc_compression;  84 unsigned short
rohc_ip_version;  85 gboolean cid_inclusion_info;  86 gboolean
large_cid_present;  87 enum rohc_mode mode;  88 gboolean rnd;  89 gboolean
udp_checkum_present;  90 unsigned short profile;
> From a very quick look, I see that your implementation is hard-wired to
RTP/IPv4, and comments about maybe using preferences or conversation info to
work out other fields.  My preference would be to attach info similar to the
above, and let each user fill it in as they can (leaving the possibility to
override with preferences).

My very next task happens to be to configure LTE PDCP, RLC and MAC with info
found in RRC, and some of these fields can be given then, whereas others are
the internal state of the contexts, which is hard to know (without doing a
full ROHC simulation!)...

It'd be good to merge them into one standalone dissector that I could then
call from PDCP (LTE and UMTS sometime).  I noticed for example that you
don't decode all of the feedback options, so maybe my implementation could
help speed up the adding of some of these.

There is a screenshot of my decoder in http://wiki.wireshark.org/PDCP-LTE,
but I expect I could send you a trace file later on.

Best regards,
Martin




>  On Sat, Apr 16, 2011 at 12:44 PM, <etxrab () wireshark org> wrote:
>
> > http://anonsvn.wireshark.org/viewvc/viewvc.cgi?view=rev&revision=36659
> >
> > User: etxrab
> > Date: 2011/04/16 04:44 AM
> >
> > Log:
> >  Add a basic ROCH dissector.
> >  Limitations:
> >  - Small CID
> >  - RTP profile
> >  - IPv4
> >
> > Directory: /trunk/epan/dissectors/
> >  Changes    Path               Action
> >  +4 -3      Makefile.common    Modified
> >  +984 -0    packet-rohc.c      Added
> >
> >
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