Wireshark-dev: Re: [Wireshark-dev] Buffering packets for dissection
From: Andreas <[email protected]>
Date: Wed, 28 Jul 2010 05:57:18 +0000 (UTC)
Jaap Keuter <[email protected]> writes:

> Hi,
> What's your transport protocol?
> Thanks,
> Jaap
> On Mon, 26 Jul 2010 16:29:42 +0300 (EEST), [email protected]
> wrote:
> > Hello,
> > 
> > I'm currently writing a dissector which requires packet buffering to
> > work. The dissector more or less has to brute-force the packet stream
> > to find the actual data, but it needs at least a dozen packets of data
> > before it can do anything. So, it doesn't know when the data begins,
> > and how much data it needs (there is a maximum possible length
> > though).
> > 
> > Is there any built-in support for this? I was able to store the tvb
> > buffers into a circular buffer, but I'm not quite sure what to do with
> > the packet_info structure (I may be wrong, but it didn't seem to be on
> > the heap, so I couldn't just store the pointer to it).
> > 
> > Any help is appreciated!
> > 
> > Sincerely,
> > Andreas
> > 


I'm using UDP for testing purposes, just to get the data into Wireshark. 
I have sample files of raw PCM data which I then export to pcap format using
text2pcap, and insert dummy UDP headers. 
Basically, I get 40 PCM samples per packet, from which I extract a few bits here
and there. That's why I have to scan through a lot of packets, because I do not
know where I find the sync bits.