URL: https://code.wireshark.org/review/gitweb?p=wireshark.git;a=commit;h=5222e5f95cbddd87b04a812b0cc1aece7941a5ca
Submitter: Pascal Quantin (pascal.quantin@xxxxxxxxx)
Changed: branch: master-2.4
Repository: wireshark
Commits:
5222e5f by Harald Welte (laforge@xxxxxxxxxxxx):
rsl: Fix treatment of SACCH FILL / SACCH INFO MODIFY
The RSL SACCH INFO MODIFY / RSL SACCH FILL messages contain a
SI5 / SI6 / SI5bis / SI5ter message. Those SI are (like the SI on CCCH)
sent as UI frame in downlink direction. Since Phase 2, the "L2
pseudo-length field is part of the L3 message, and not stripped /
interpreted at L2.
3GPP TS 44.006 states that a special B4 frame format is used on the
SACCH downlink for UI frames, which is basically a normal B frame, but
with no length field at L2, shifting the length field into L3 where it
becomes the L2 pseudo-length.
From RSL, we need to call a variant of the RR dissector that is able to
decode a L3 message that includes a L2 pseudo-length. This is,
paradoxically, not the "gsm_a_sacch" dissector, as that one is only used
for B-frames, i.e. actual LAPDm ABM frames. We must use the "gsm_a_ccch"
dissector.
See also the discussion in
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=14105
as well as https://lists.osmocom.org/pipermail/openbsc/2017-December/011545.html
and https://osmocom.org/issues/3059 for further background information.
Ping-Bug: 14105
Change-Id: Icdad2b7698d5d7d613cacceec6a3d848b946306c
Reviewed-on: https://code.wireshark.org/review/26797
Reviewed-by: Pascal Quantin <pascal.quantin@xxxxxxxxx>
Petri-Dish: Pascal Quantin <pascal.quantin@xxxxxxxxx>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@xxxxxxxxx>
(cherry picked from commit 91e0de19c921b91401421b06bd2b90cdbe1c7166)
Reviewed-on: https://code.wireshark.org/review/26982
Actions performed:
from 4feafbb [Automatic update for 2018-04-15]
adds 5222e5f rsl: Fix treatment of SACCH FILL / SACCH INFO MODIFY
Summary of changes:
epan/dissectors/packet-rsl.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)