Re: MPEG2-TS, DVB-SI, and DVB-GSE Dissectors

[Paul Williamson <paul () mustbeart com>]

Hi Alexander,

I was the last one to contribute to the GSE dissector implementation in
epan/dissectors/packet-dvb-s2-bb.c.

My involvement is through an amateur radio project (Phase 4 Ground) that is
planning to use DVB-S2 for a ham radio (non-broadcast) satellite downlink.
As such, I'm not very connected into the industry standards process, so I
was unaware of parts 2 and 3 of TS102606. I'll study them now, thanks for
the pointer.

The current dissector does not handle GSE fragmentation reassembly. Adding
that is on my to-do list, but not at the top of the list. I'm guessing you
may want to have reassembly before you add more protocol level support. You
and I should coordinate to avoid duplication of effort on this.

This work on the GSE dissector is all I've done with Wireshark, so I'm a
beginner here, too. I'm not sure what other hints to offer you. I'd be
happy to coordinate with you off-list and assist you however I can.

  -Paul
paul () mustbeart com


On Tue, Mar 14, 2017 at 7:08 AM, Alexander Adolf <
alexander.adolf () condition-alpha com> wrote:

> Dear Wireshark MPEG/DVB Developers,
>
> My name is Alexander Adolf, and I have just newly subscribed to
> wireshark-dev. I
> am the maintainer of EN300468, TS101211, all three documents of the
> TS102606 suite, and TS102771. This is of course part of my work as a member
> of the DVB Project. Today I am however not writing to you in this official
> capacity, but as a member of the broadcast community at large.
>
> For many, many years I have been a most happy user of Wireshark for
> tracking down network problems. It is an indispensable tool to me, and IMO
> better than the vast majority of commercial low-level protocol analysers.
> And the manyfold of supported application layer protocols is simply
> unparalleled. Full stop.
>
> Many thanks for making this project the great tool it is!
>
> In this light, I thought I should try to also contribute something by
> sharing my expertise in DVB protocols. Apparently this is not entirely
> unselfish, as it could make Wireshark an even more indispensable tool in my
> day to day hacking.
> ;-)
>
> My interest would be to contribute in two areas:
>
> (1) A little bit of streamlining of how DVB PSI/SI is presented when
> analysing MPEG2-TS. I could e.g. imagine it to help readability if the PID
> were shown in the source and/or destination address field. Also, when
> interpreting DVB PSI/SI tables, some interpretations of identifiers doesn't
> seem to be quite accurate.
>
> (2) The DVB-GSE specification TS102606 has been split to become a
> three-part document. This added a logical link control protocol (LLC) and
> support for robust header compression for IP (ROHC-U / RFC 5795, RFC 3095,
> RFC 4815). I'd thus volunteer to help add support for both new features to
> the DVB-GSE implementation so that those PLPs/ISIs that carry GSE with IP
> payload can be presented as IP traffic in Wireshark. Test streams? Yes,
> that'll inevitably have to be part of the game.
>
>
> For both topics, I would expect one likely guidance I'll be receiving to
> be "submit a patch". This is of course the most productive and easiest to
> manage way from the point of view of the regular contributors who are
> familiar with the code - i.e. you. To help me in making useful
> contributions, it would be great if someone familiar with the code in the
> mentioned "corners" of the code base could give me a short list of hints
> where to start looking.
>
>
> Many thanks in advance and looking forward to your thoughts,
>
>   --alexander
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