laforge has uploaded this change for review.
cbsp: Reject CBSP WRITE for emergency if emergency already active
From 3GPP TS 48.018:
If only the New Serial Number IE, and not the Old Serial Number IE, is
included in the WRITE-REPLACE message,then the BSC shall interpret the
message as a write request, i.e. a broadcast request of a new emergency
message without replacing an ongoing emergency message broadcast.
Only one emergency message at the time can be broadcasted in a cell. If
a write request is received for a cell where an emergency message
broadcast is currently ongoing, the write request is considered as
failed.
Change-Id: I376c9e796f3a2d26b22d0451f15ef1debbd7f656
Closes: OS#5539
Related: SYS#5906
---
M src/osmo-bsc/smscb.c
1 file changed, 28 insertions(+), 3 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/63/27963/1
diff --git a/src/osmo-bsc/smscb.c b/src/osmo-bsc/smscb.c
index 873d665..2b37df9 100644
--- a/src/osmo-bsc/smscb.c
+++ b/src/osmo-bsc/smscb.c
@@ -494,13 +494,37 @@
etws_pn_stop(bts, true);
}
-static void etws_primary_to_bts(struct gsm_bts *bts, const struct osmo_cbsp_write_replace *wrepl)
+static int etws_primary_to_bts(struct gsm_bts *bts, const struct osmo_cbsp_write_replace *wrepl)
{
struct bts_etws_state *bes = &bts->etws;
struct gsm_bts_trx *trx;
unsigned int count = 0;
int i, j;
+ if (bes->active) {
+ /* we were already broadcasting emergency before receiving this WRITE-REPLACE */
+
+ /* If only the New Serial Number IE, and not the Old Serial Number IE, is included in the
+ * WRITE-REPLACE message, then the BSC shall interpret the message as a write request, i.e. a
+ * broadcast request of a new emergency message without replacing an ongoing emergency message
+ * broadcast. */
+ if (!wrepl->old_serial_nr) {
+ /* If a write request is received for a cell where an emergency message broadcast is
+ * currently ongoing, the write request is considered as failed */
+ LOG_BTS(bts, DCBS, LOGL_NOTICE, "Rx CBSP WRITE rejected due to ongoing emergency "
+ "while no Old Serial Nr IE present in CBSP WRITE\n");
+ return -CBSP_CAUSE_BSC_CAPACITY_EXCEEDED;
+ }
+
+ if (!etws_msg_id_matches(*wrepl->old_serial_nr, bes->input.serial_nr)) {
+ LOG_BTS(bts, DCBS, LOGL_NOTICE, "Rx CBSP WRITE-REPLACE old_serial 0x%04x doesn't match "
+ "current serial 0x%04x. Is the CBC confused?\n",
+ *wrepl->old_serial_nr, bes->input.serial_nr);
+ /* we allow the WRITE-REPLACE to continue, TS 48.049 doesn't specify how to
+ * handle situations like this */
+ }
+ }
+
if (bes->input.sec_info) {
talloc_free(bes->input.sec_info);
bes->input.sec_info = NULL;
@@ -554,6 +578,8 @@
} else
LOG_BTS(bts, DCBS, LOGL_NOTICE, "Unlimited ETWS PN broadcast, this breaks "
"normal network operation due to PCH blockage\n");
+
+ return 0;
}
/*! Try to execute a write-replace operation; roll-back if it fails.
@@ -625,8 +651,7 @@
int rc;
if (!wrepl->is_cbs) {
- etws_primary_to_bts(bts, wrepl);
- return 0;
+ return etws_primary_to_bts(bts, wrepl);
}
/* check if cell has a CBCH at all */
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