Wireshark · Wireshark-dev: Re: [Wireshark-dev] Text2pcap and bidirectional traffic

["Abhik Sarkar" <sarkar.abhik@xxxxxxxxx>]

Hi Patrick!

Due you really need the TCP and lower layers (for example, if you make
use of the conversations API)? If not, you could simply use text2pcap
with a user DLT to test only your protocol layer:
http://wiki.wireshark.org/HowToDissectAnything (the page needs a bit
of an update to match the latest versions... I'll see if I can do that
later today, but you should get the idea (if you don't already know,
that is)).

What you are proposing of course could be quite useful. It might be
worth opening an enhancement bug report with your initial approach (so
that the idea doesn't get lost) and someone might be able to provide
further ideas.

HTH
Abhik.

On Tue, Jul 22, 2008 at 8:50 AM, Barnes, Pat
<Pat.Barnes@xxxxxxxxxxxxxxxxxx> wrote:
>
> I don't have any traffic to test my dissector against, because the
> components in the system that will be generating that traffic aren't
> ready yet.
>
> Until then, I've used text2pcap to construct some capture files from
> scratch. There is a bit of a problem though: The -T (add TCP headers)
> option results in packets only going in one direction.
>
> As a bit of hack, I've put this code in the process_directive function:
>
> static void
> process_directive (char *str)
> {
>        guint32 tmp;
>
>        str += 11; //Strip off the #TEXT2PCAP and first space
>        if (strncmp("INVERT", str, 6) == 0) {
>                if (hdr_ip) {
>                        tmp = HDR_IP.src_addr;
>                        HDR_IP.src_addr = HDR_IP.dest_addr;
>                        HDR_IP.dest_addr = tmp;
>                }
>                if (hdr_tcp || hdr_udp) {
>                        tmp = hdr_src_port;
>                        hdr_src_port = hdr_dest_port;
>                        hdr_dest_port = tmp;
>                }
>                fprintf(stdout, "Inverted source and destination \n");
>        } else {
>                fprintf(stderr, "\n--- Directive [%s] currently
> unsupported ---\n", str-11);
>        }
> }
>
> Such that a '#TEXT2PCAP INVERT' will switch the directions around.
>
> The only downside to this approach is that it mucks up the TCP sequences
> - subsequent packets have a 'TCP segment lost' warning. Any suggestions
> on how to suppress/fix that, or otherwise enhance text2pcap?
>
> ----------------------------------
> Patrick Barnes
> Software Engineer
> Land & Joint Systems
>
> Thales Australia
> 274 Victoria Road, Rydalmere, NSW 2116, Australia
> Tel: +61 2 9848 3857
> Mob: +61 410 751 044
> | www.thalesgroup.com.au
> ----------------------------------
>
>
>
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