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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
(cherry picked from commit 24567cfeed)
This commit is contained in:
Harald Welte 2022-04-25 11:58:46 +02:00
parent cab2fb2a28
commit fdd3ccbc02
1 changed files with 28 additions and 3 deletions
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31
src/osmo-bsc/smscb.c
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@ -494,13 +494,37 @@ static void etws_pn_cb(void *data)
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;
@ -553,6 +577,8 @@ static void etws_primary_to_bts(struct gsm_bts *bts, const struct osmo_cbsp_writ
} 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.
@ -624,8 +650,7 @@ static int bts_rx_write_replace(struct gsm_bts *bts, const struct osmo_cbsp_deco
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 */