fragment_add_check() & frag_offset

[David Aggeler <david_aggeler () hispeed ch>]

I'm trying to get fragment_add_check() working and I did make quite a 
bit of progress. D03_Harris_Writing Wireshark Dissectors_Advanced.pdf 
was a good start, but is missing the details I need to know. Debugging 
helped, but now I'm somewhat stuck with the frag_offset parameter.

DICOM does not have any byte counter in the fragments, so all fragments 
need to be merged back-to-back.

Is there an elegant way to let fragment_add_check() resp. 
fragment_add_work() doing that, or is the dissector supposed to always 
deliver this?
If the later is the case, in order to know how much my reassembly 
already progressed, I would need to keep multiple sorted lists of 
fragments and their length, i.e. using my own hash tables. So I have a 
hard time to believe, this is what should be done.

However, the comment in packet-smb-pipe.c, line 3367 is not very 
motivating "instead of assuming we always get them in the correct 
order".  I expect fragment_add_check() to handle the packet order.

So any hint on the API usage or directions to documentation I may have 
missed would be appreciated.

David



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