Ethereal-dev: Re: [Ethereal-dev] Dissector for MATIP Type A conversational traffic.
On Sep 15, 2003, at 9:25 PM, Jonathan_Fernandes@xxxxxxxxxxxxxxxxxxx
wrote:
guint8 mpx; /* ugly, but I need mpx for two functions
(session open, and the open_confirm() ) */
That won't work, unless the session open and open confirm are in the
same frame, or if your capture has exactly one session open packet in
it. Given that an open confirm is a response to a session open,
they're unlikely to be in the same frame.
This means that will work *only* if you have exactly one session in
your capture, or if you *always* click on the "session open" packet for
a session before clicking on the corresponding "open confirm". There
is no guarantee that, except on the first pass through a capture, your
dissector will be called on packets in the order they are in the
capture file - a user can click on packets in whatever order they want.
What you should do is:
1) in the "session open" dissector, set up a conversation for the TCP
connection, and attach the pmx value to the conversation as
conversation data for the MATIP protocol;
2) in the "open confirm" dissector, fetch the mpx value from the
conversation, if there is a conversation. (If there isn't a
conversation, or there is but there's no mpx value attached to it -
those could happen if the "session open" isn't in the capture - you
won't be able to dissect the ASCUs unless you assume it's 0 if it's not
present).
Also, there are some typos - "Applicatation" instead of "Application",
and "dependant" instead of "dependent".
