Fwd: understanding DT1 reassembly

[Ariel Burbaickij <ariel.burbaickij () gmail com>]

OK, maybe wireshark-users was a wrong list with little in terms of overlap
with wireshakr-dev. So, could you, please, shed some light on the topic
raised?

---------- Forwarded message ----------
From: Ariel Burbaickij <ariel.burbaickij () gmail com>
Date: Sat, Nov 23, 2013 at 10:08 AM
Subject: understanding DT1 reassembly
To: Community support list for Wireshark <wireshark-users () wireshark org>


Hello all,
as far as I understand from packet-sccp.c DT1 reassembly is supported by
now, SLR is used for look up in the hash table, segmentation/reassembly
mask is used for deciding whether there will be more segments or not.
packet-sccp.c is more or less piece of cake to understand, reassembly.c, of
course, in its generality, not quite so. So, it would be great if somebody
could help me to understand following aspect:
How wireshark discerns following two possibilities:
1) first AND last DT1 segment (no more segments in the
segmentation/reassembly mask)
2) last DT1 segment  (also no more segments in the segmentation/reassembly
mask)

what I mean in particular with discerning is how wireshark "knows" not to
attempt to dissect/decode isolated last DT1 segment (no more data are
announced here too, after all!), in particular with corner case of the last
segment arriving first in mind?

/wbr
Ariel Burbaickij

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