bsc/ussd: Optionally send USSD message on MSC disconnection

Send an USSD message on each MS connection if the connection to
the MSC has been lost.
Add a vty config command 'bsc-msc-loss-txt' in 'config-msc' to set
the notification string and to enable the feature.

Ticket: OW#957

2 files changed, 61 insertions, 4 deletions

diff --git a/openbsc/src/osmo-bsc/osmo_bsc_sccp.c b/openbsc/src/osmo-bsc/osmo_bsc_sccp.c
index 3533d6df0..ad554e82a 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_sccp.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_sccp.c
@@ -262,13 +262,35 @@ int bsc_delete_connection(struct osmo_bsc_sccp_con *sccp)
 	return 0;
 }
 
-static void bsc_close_connections(struct bsc_msc_connection *msc_con)
+static void bsc_notify_msc_lost(struct osmo_bsc_sccp_con *con)
+{
+	struct gsm_subscriber_connection *conn = con->conn;
+
+	/* send USSD notification if string configured and con->data is set */
+	if (!conn)
+		return;
+
+	/* check for config string */
+	if (!con->msc->ussd_msc_lost_txt)
+		return;
+	if (con->msc->ussd_msc_lost_txt[0] == '\0')
+		return;
+
+	/* send USSD notification */
+	gsm0480_send_ussdNotify(conn, 1, conn->sccp_con->msc->ussd_welcome_txt);
+	gsm0480_send_releaseComplete(conn);
+}
+
+static void bsc_notify_and_close_conns(struct bsc_msc_connection *msc_con)
 {
 	struct osmo_bsc_sccp_con *con, *tmp;
 
 	llist_for_each_entry_safe(con, tmp, &active_connections, entry) {
-		if (con->msc->msc_con == msc_con)
-			bsc_sccp_force_free(con);
+		if (con->msc->msc_con != msc_con)
+			continue;
+
+		bsc_notify_msc_lost(con);
+		bsc_sccp_force_free(con);
 	}
 }
 
@@ -282,7 +304,7 @@ static int handle_msc_signal(unsigned int subsys, unsigned int signal,
 
 	msc = signal_data;
 	if (signal == S_MSC_LOST)
-		bsc_close_connections(msc->data->msc_con);
+		bsc_notify_and_close_conns(msc->data->msc_con);
 
 	return 0;
 }
diff --git a/openbsc/src/osmo-bsc/osmo_bsc_vty.c b/openbsc/src/osmo-bsc/osmo_bsc_vty.c
index 49ae665a6..501d9f51b 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_vty.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_vty.c
@@ -114,6 +114,11 @@ static void write_msc(struct vty *vty, struct osmo_msc_data *msc)
 	if (msc->ussd_welcome_txt)
 		vty_out(vty, " bsc-welcome-text %s%s", msc->ussd_welcome_txt, VTY_NEWLINE);
 
+	if (msc->ussd_msc_lost_txt && msc->ussd_msc_lost_txt[0])
+		vty_out(vty, " bsc-msc-lost-text %s%s", msc->ussd_msc_lost_txt, VTY_NEWLINE);
+	else
+		vty_out(vty, " no bsc-msc-lost-text%s", VTY_NEWLINE);
+
 	if (msc->audio_length != 0) {
 		int i;
 
@@ -368,6 +373,34 @@ DEFUN(cfg_net_msc_welcome_ussd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_net_msc_lost_ussd,
+      cfg_net_msc_lost_ussd_cmd,
+      "bsc-msc-lost-text .TEXT",
+      "Set the USSD notification to be sent on MSC connection loss\n" "Text to be sent\n")
+{
+	struct osmo_msc_data *data = osmo_msc_data(vty);
+	char *str = argv_concat(argv, argc, 0);
+	if (!str)
+		return CMD_WARNING;
+
+	bsc_replace_string(osmo_bsc_data(vty), &data->ussd_msc_lost_txt, str);
+	talloc_free(str);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_net_msc_no_lost_ussd,
+      cfg_net_msc_no_lost_ussd_cmd,
+      "no bsc-msc-lost-text",
+      NO_STR "Clear the USSD notification to be sent on MSC connection loss\n")
+{
+	struct osmo_msc_data *data = osmo_msc_data(vty);
+
+	talloc_free(data->ussd_msc_lost_txt);
+	data->ussd_msc_lost_txt = 0;
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_net_msc_type,
       cfg_net_msc_type_cmd,
       "type (normal|local)",
@@ -579,6 +612,8 @@ int bsc_vty_init_extra(void)
 	install_element(MSC_NODE, &cfg_net_msc_ping_time_cmd);
 	install_element(MSC_NODE, &cfg_net_msc_pong_time_cmd);
 	install_element(MSC_NODE, &cfg_net_msc_welcome_ussd_cmd);
+	install_element(MSC_NODE, &cfg_net_msc_lost_ussd_cmd);
+	install_element(MSC_NODE, &cfg_net_msc_no_lost_ussd_cmd);
 	install_element(MSC_NODE, &cfg_net_msc_type_cmd);
 	install_element(MSC_NODE, &cfg_net_msc_emerg_cmd);
 	install_element(MSC_NODE, &cfg_net_msc_local_prefix_cmd);