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The sequence number in COTP packets is either unused (for TP0) or 

relative to the beginning of the connection (for TP1-4).  They are *not*
relative to the first segment of a segmented TPDU, so the sequence
number can't be used in calls to "fragment_add_seq_check()".

For now, we assume that COTP packets are seen in order, and just use
"fragment_add_seq_next()" - that's unlikely to make anything worse (the
only time when "fragment_add_seq_check()" will work is when the first
segment has a sequence number of 0), and definitely fixes reassembly in
a number of cases.  In the long term, we might want to handle
out-of-order packets above the reassembly layer, so that it handles even
out-of-order unsegmented packets.

svn path=/trunk/; revision=11188
This commit is contained in:
Guy Harris 2004-06-20 01:05:07 +00:00
parent 915f02d0f5
commit 5b96828900
1 changed files with 12 additions and 4 deletions
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16
packet-clnp.c
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@ -1,7 +1,7 @@
/* packet-clnp.c
* Routines for ISO/OSI network and transport protocol packet disassembly
*
* $Id: packet-clnp.c,v 1.85 2004/05/24 02:25:18 guy Exp $
* $Id: packet-clnp.c,v 1.86 2004/06/20 01:05:07 guy Exp $
* Laurent Deniel <laurent.deniel@free.fr>
* Ralf Schneider <Ralf.Schneider@t-online.de>
*
@ -990,11 +990,19 @@ static int ositp_decode_DT(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
* segmented packet doesn't have a specific sequence number (e.g., 0
* or 1), it has whatever the appropriate sequence number is for
* it in the connection.
*
* For now, we assume segments arrive in order, and just supply
* the negation of the EOT flag as the "more flags" argument.
* We should probably handle out-of-order packets separately,
* so that we can deliver them in order even when *not*
* reassembling.
*
* Note also that TP0 has no sequence number, and relies on
* the protocol atop which it runs to guarantee in-order delivery.
*/
fd_head = fragment_add_seq_check(next_tvb, 0, pinfo, dst_ref,
cotp_segment_table,
fd_head = fragment_add_seq_next(next_tvb, 0, pinfo, dst_ref,
cotp_segment_table,
cotp_reassembled_table,
tpdu_nr,
fragment_length, fragment);
if (fd_head) {
if (fd_head->next) {