-----Original Message-----
From: Wireshark-dev <wireshark-dev-bounces@xxxxxxxxxxxxx> On Behalf Of Guy
Harris
Sent: den 9 juli 2020 04:00
To: Developer support list for Wireshark <wireshark-dev@xxxxxxxxxxxxx>
Subject: Re: [Wireshark-dev] Reassembling IPP info through USB
On Jul 8, 2020, at 6:06 PM, Jamie Hare <jamie.n.hare@xxxxxxxxx> wrote:
> I am attempting to create a dissector for IPP over USB and am running into
> some issues with the reassembly. I first thought that I could just use a
> reassembly table but with the way the dissectors are run multiple times is
> it necessary to create a PDU/tap combo like TCP or UDP?
Taps are not used for reassembly of PDUs that cover multiple TCP segments or
multiple UDP datagrams, so taps are not necessary for reassembly of
IPP-over-USB.
You *do* need to make sure that, in the first pass over the packets, the
results of the reassembly are saved, just as happens with reassembly with
other packets, so that, when packets are looked at, in a possibly random
order, after the first pass, it can be determined where the packet in question
resides within the reassembled IPP message.
pinfo->fd->visited can be used to track if it's the first pas or not. If you
search for it in the code you can find how it is used with reassembly in
many(all) cases.
Regards
Anders
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