Re: Index of multiple protocol frames in one packet?

[Pascal Quantin <pascal.quantin () gmail com>]

2015-10-12 17:35 GMT+02:00 Jeff Morriss <jeff.morriss.ws () gmail com>:

> On 10/06/15 02:17, Pascal Quantin wrote:
>
> > 2015-10-06 8:07 GMT+02:00 Petr Gotthard <petr.gotthard () centrum cz
> > <mailto:petr.gotthard () centrum cz>>:
> >
> >     Hello,
> >
> >     Is there a way to distinguish multiple frames of the same protocol
> >     in one TCP/IP packet? I have several small AMQP frames which all fit
> >     into a single IP frame, so they share a single packet_info
> >     structure.When I call p_add_proto_data() for the second AMQP frame,
> >     it (obviously) overwrites data stored for the first frame, so I need
> >     to distibguish between them somehow.
> >
> >     Is there a counter that would tell me "this is a third AMQP frame in
> >     this pinfo"? I found packet_info->curr_layer_num, but this is useful
> >     for nested frames (like IP in IP). Is there something similar for
> >     groupped frames, please?
> >
> >
> > Hi Peter,
> >
> > I'm not sure we have such counter, but
> > https://code.wireshark.org/review/#/c/10579/ suggested the use of
> > tvb_raw_offset as key for p_(add|get)_proto_data() functions which seems
> > a good tradeoff.
>
> Actually there is such a counter in frame_data: subnum.  But it's not
> widely used: for now it's only used in EPL, RRC, and UMTS_FP.


Thanks for the hint Jeff (I did not know this one).

It appears that frame_data.c is only setting it to 0, and that increment
need to be handled directly by dissectors. So it means that for a wider
usage, (tcp|udp)_dissect_pdus() function (among others) should be modified
so as to increment it when calling a new subdissector.

Cheers,
Pascal.

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