Re: How to get UDP port numbers in sub-dissector

[eymanm <eymanm () gmail com>]

I'm dealing with case #2. My protocol runs on top of UDP, or
perhaps, encapsulated into UDP. So I tryed this:

    if (check_col(pinfo->cinfo,COL_INFO)) {
        col_clear(pinfo->cinfo,COL_INFO);
    }

    col_add_fstr(pinfo->cinfo, COL_INFO, "Source: %s", pinfo->srcport);

When I run, it puts "[Dissector bug, protocol XXX: STATUS_ACCESS_VIOLATION:
dissector accessed and invalid memory address]" in the Info column.

What am I doing wrong?
Thanks


On Mon, May 23, 2011 at 1:41 PM, Guy Harris <guy () alum mit edu> wrote:

> On May 23, 2011, at 7:55 AM, eymanm wrote:
>
> > I'm making a dissector for a protocol that is based on UDP.
>
> By "based on UDP", do you mean:
>
>        1) your protocol is an unreliable transport-layer protocol similar
> to UDP but not the same as UDP
>
> or
>
>        2) your protocol runs on top of UDP?
>
> > I'd like to show the source and destination ports in the Info column,
> pretty much the same way as it shown by the UDP dissector. Can somebody
> suggest how to get the  port numbers when I'm dissecting the payload?
>
> If the answer is 1), then, if your protocol has port numbers, you get them
> from your dissector.
>
> If the answer is 2), the packet_info structure pointed to by the "pinfo"
> argument to your dissector has "srcport" and "dstport" members that, for a
> protocol running atop UDP, have the UDP source and destination port numbers.
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