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

openbsc/include/openbsc/osmo_msc_data.h

@@ -83,6 +83,9 @@ struct osmo_msc_data {
 	struct osmo_wqueue mgcp_agent;
 
 	int nr;
+
+	/* ussd msc connection lost text */
+	char *ussd_msc_lost_txt;
 };
 
 /*

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;
 }

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);

openbsc/tests/vty_test_runner.py

@@ -88,6 +88,39 @@ class TestVTYNITB(TestVTYBase):
         self.assertEquals(res.find('periodic location update 60'), -1)
         self.assert_(res.find('no periodic location update') > 0)
 
+class TestVTYBSC(TestVTYBase):
+
+    def vty_command(self):
+        return ["./src/osmo-bsc/osmo-bsc", "-c",
+                "doc/examples/osmo-bsc/osmo-bsc.cfg"]
+
+    def vty_app(self):
+        return (4242, "./src/osmo-bsc/osmo-bsc", "OsmoBSC", "bsc")
+
+    def testUssdNotifications(self):
+        self.vty.enable()
+        self.vty.command("configure terminal")
+        self.vty.command("msc")
+
+        # Test invalid input
+        self.vty.verify("bsc-msc-lost-text", ['% Command incomplete.'])
+
+        # Enable USSD notifications
+        self.vty.verify("bsc-msc-lost-text MSC disconnected", [''])
+
+        # Verify settings
+        res = self.vty.command("write terminal")
+        self.assert_(res.find('bsc-msc-lost-text MSC disconnected') > 0)
+        self.assertEquals(res.find('no bsc-msc-lost-text'), -1)
+
+        # Now disable it..
+        self.vty.verify("no bsc-msc-lost-text", [''])
+
+        # Verify settings
+        res = self.vty.command("write terminal")
+        self.assertEquals(res.find('bsc-msc-lost-text MSC disconnected'), -1)
+        self.assert_(res.find('no bsc-msc-lost-text') > 0)
+
 class TestVTYNAT(TestVTYBase):
 
     def vty_command(self):
@@ -189,6 +222,13 @@ def add_nat_test(suite, workdir):
     test = unittest.TestLoader().loadTestsFromTestCase(TestVTYNAT)
     suite.addTest(test)
 
+def add_bsc_test(suite, workdir):
+    if not os.path.isfile(os.path.join(workdir, "src/osmo-bsc/osmo-bsc")):
+        print("Skipping the BSC test")
+        return
+    test = unittest.TestLoader().loadTestsFromTestCase(TestVTYBSC)
+    suite.addTest(test)
+
 if __name__ == '__main__':
     import argparse
     import sys
@@ -219,6 +259,7 @@ if __name__ == '__main__':
     print "Running tests for specific VTY commands"
     suite = unittest.TestSuite()
     suite.addTest(unittest.TestLoader().loadTestsFromTestCase(TestVTYNITB))
+    add_bsc_test(suite, workdir)
     add_nat_test(suite, workdir)
     res = unittest.TextTestRunner(verbosity=verbose_level).run(suite)
     sys.exit(len(res.errors) + len(res.failures))