Wireshark-commits: [Wireshark-commits] master 91e0de1: rsl: Fix treatment of SACCH FILL / SACCH INF
URL: https://code.wireshark.org/review/gitweb?p=wireshark.git;a=commit;h=91e0de19c921b91401421b06bd2b90cdbe1c7166
Submitter: Anders Broman (a.broman58@xxxxxxxxx)
Changed: branch: master
Repository: wireshark
Commits:
91e0de1 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>
Actions performed:
from 57bf7e4 Qt: Fix memory leak for CaptureEvent
adds 91e0de1 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(-)
