Wireshark-dev: Re: [Wireshark-dev] Reassembling IPP info through USB
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From: Guy Harris <gharris@xxxxxxxxx>
Date: Wed, 8 Jul 2020 18:59:31 -0700
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.