Ethereal-dev: Re: [Ethereal-dev] Re: Order of tap listeners (PATCH)

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From: "Lars Ruoff" <Lars.Ruoff@xxxxxxxxxx>
Date: Fri, 1 Apr 2005 09:15:42 +0200
> The VoIP calls analysis function registers taps for different protocols
that can be
> inside the same packet -e.g. SIP and SDP, or MTP and ISUP-. Would the
patch affect the
> behaviour in this case?

Well, no, unless your code relies on the specific "undefined" tap call order
we had till now ;-)
It was: The protocol item which called tap_queue_packet last got its tap
called first (LIFO).
I suggest changing it to calling the taps in strictly the same order as the
different dissectors call "tap_queue_packet" for a given packet (FIFO).

Since most dissectors call tap_queue_packet at the very end of dissection
(after having called sub-dissectors) that might brake some code that uses
taps at different protocol levels and shares state information among these
(and relies on taps of higher level protocols beign called *before* lower
level protocols).
Again, if this is the case, the code *was* already broken with regard to the
current documentation in which the order of tap listeners is explicitly
stated as "undefined".
Could you check if that might be a problem for VoIP calls?

regards,
Lars Ruoff

>
> Regards,
>   Francisco
>
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