Re: New DVB_CI dissector: Discussion as to approach

[Guy Harris <guy () alum mit edu>]

On Feb 10, 2011, at 11:38 AM, Bill Meier wrote:

> There are two approaches to processing the pseudo-header:
>
> 1. libpcap processes the pseudo-header and fills in a dissector-specific structure which is eventually passed to the 
> DVBCI dissector (pinfo->pseudo_header) along with the actual data.
>
>  See wiretap/libpcap.c wiretap/pcap-common.c/process_pseudo_header()
>  and epan/dissectors/packet-frame.c
>
>   This approach is used by most of the dissectors which need info
>   such as "direction".
>
> 2. The dissector processes both the pseudo-header and the actual data.
>   I.E., From the Wireshark perspective, the pseudo-header is just part
>   of the captured data (similar to the code in your original patch).
>
>   This is the approach used by packet-radiotap.c
>
> ---------
>
> I don't know if there are reasons to prefer the first approach even if the changes (other than the dissector itself) 
> are slightly more extensive. (Code must be added to libpcap to handle the pseudo-header).
>
> I expect one of the other core-developers (Guy ?) can give some guidance.

At this point, I prefer the second approach.  The Linux USB dissector now uses that, as of revision 32534; switching to 
that cleaned things up.
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