Harald Welte has submitted this change and it was merged.

Change subject: abis_rsl: do not allow SACCH in MF mode on SAPI=0
......................................................................


abis_rsl: do not allow SACCH in MF mode on SAPI=0

osmo-msc does currently not check if an MS attemts to establish an
SACCH link on SAPI=0. This combination is not permitted and should
be dropped.

- Make sure that establish indication for SAPI=0 and channel-type=SACCH
  is not permitted

See also TTCN3 Testcase:
BSC_Tests.TC_rll_est_ind_inval_sacch

Change-Id: I12962072c0ea689d2b9b5c2899ffb59be9310dcb
Closes: OS#2750
---
M src/libbsc/abis_rsl.c
1 file changed, 15 insertions(+), 0 deletions(-)

Approvals:
  Harald Welte: Looks good to me, approved
  Jenkins Builder: Verified



diff --git a/src/libbsc/abis_rsl.c b/src/libbsc/abis_rsl.c
index 1893166..261e6fe 100644
--- a/src/libbsc/abis_rsl.c
+++ b/src/libbsc/abis_rsl.c
@@ -2194,6 +2194,21 @@
                        break;
                }
 
+               /* Note: Check for MF SACCH on SAPI=0 (not permitted). By
+                * definition we establish a link in multiframe (MF) mode.
+                * (see also 3GPP TS 48.058, chapter 3.1. However, on SAPI=0
+                * SACCH is only allowed in UL mode, not in MF mode.
+                * (see also 3GPP TS 44.005, figure 5) So we have to drop such
+                * Establish Indications */
+               if (sapi == 0 && (rllh->link_id >> 6 & 0x03) == 1) {
+                       LOGP(DRLL, LOGL_NOTICE, "MS attempted to establish an 
SACCH in MF mode on SAPI=0 (not permitted)\n");
+
+                       /* Note: We do not need to close the channel,
+                        * since we might still get a proper Establish Ind.
+                        * If not, T3101 will close the channel on timeout. */
+                       break;
+               }
+
                msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_MS;
                osmo_timer_del(&msg->lchan->T3101);
                if (msgb_l2len(msg) >

-- 
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Gerrit-MessageType: merged
Gerrit-Change-Id: I12962072c0ea689d2b9b5c2899ffb59be9310dcb
Gerrit-PatchSet: 2
Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Owner: dexter <pma...@sysmocom.de>
Gerrit-Reviewer: Harald Welte <lafo...@gnumonks.org>
Gerrit-Reviewer: Jenkins Builder

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