bsc: Add a ctrl command to send a ussdNotify for a call

Send a non-call related SS message for an active call indentified
by the CIC of that call. As an ugly hack the order of the SS
release and the invocation are changed. That was necessary for the
E71 on a TCH. The time between notify and release was just too short.
The right would be to wait for the returnResultLast but this would
involve keeping more local state. Let's see how far we get here. It
might be necessary to change the order in the other call sites as
well.

openbsc/include/openbsc/bsc_api.h

@@ -52,4 +52,6 @@ int gsm0808_page(struct gsm_bts *bts, unsigned int page_group,
 		 unsigned int mi_len, uint8_t *mi, int chan_type);
 int gsm0808_clear(struct gsm_subscriber_connection *conn);
 
+struct llist_head *bsc_api_sub_connections(struct gsm_network *net);
+
 #endif

openbsc/include/openbsc/osmo_bsc.h

@@ -22,6 +22,9 @@ struct osmo_bsc_sccp_con {
 	struct llist_head entry;
 
 	int ciphering_handled;
+
+	/* for audio handling */
+	uint16_t cic;
 	int rtp_port;
 
 	/* SCCP connection realted */

openbsc/src/libbsc/bsc_api.c

@@ -857,3 +857,8 @@ static __attribute__((constructor)) void on_dso_load_bsc(void)
 {
 	osmo_signal_register_handler(SS_LCHAN, bsc_handle_lchan_signal, NULL);
 }
+
+struct llist_head *bsc_api_sub_connections(struct gsm_network *net)
+{
+	return &sub_connections;
+}

openbsc/src/osmo-bsc/osmo_bsc_bssap.c

@@ -299,7 +299,6 @@ static int bssmap_handle_assignm_req(struct osmo_bsc_sccp_con *conn,
 	struct osmo_msc_data *msc;
 	struct tlv_parsed tp;
 	uint8_t *data;
-	uint16_t cic;
 	uint8_t timeslot;
 	uint8_t multiplex;
 	enum gsm48_chan_mode chan_mode = GSM48_CMODE_SIGN;
@@ -322,9 +321,9 @@ static int bssmap_handle_assignm_req(struct osmo_bsc_sccp_con *conn,
 		goto reject;
 	}
 
-	cic = ntohs(read_data16(TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)));
-	timeslot = cic & 0x1f;
-	multiplex = (cic & ~0x1f) >> 5;
+	conn->cic = ntohs(read_data16(TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)));
+	timeslot = conn->cic & 0x1f;
+	multiplex = (conn->cic & ~0x1f) >> 5;
 
 	/*
 	 * Currently we only support a limited subset of all

openbsc/src/osmo-bsc/osmo_bsc_ctrl.c

@@ -25,6 +25,7 @@
 #include <openbsc/osmo_bsc_rf.h>
 #include <openbsc/osmo_msc_data.h>
 #include <openbsc/signal.h>
+#include <openbsc/gsm_04_80.h>
 
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/core/signal.h>
@@ -631,6 +632,78 @@ static int verify_net_inform_msc(struct ctrl_cmd *cmd, const char *value, void *
 	return 0;
 }
 
+CTRL_CMD_DEFINE(net_ussd_notify, "ussd-notify-v1");
+static int get_net_ussd_notify(struct ctrl_cmd *cmd, void *data)
+{
+	cmd->reply = "There is nothing to read";
+	return CTRL_CMD_ERROR;
+}
+
+static int set_net_ussd_notify(struct ctrl_cmd *cmd, void *data)
+{
+	struct gsm_subscriber_connection *conn;
+	struct gsm_network *net;
+	char *saveptr = NULL;
+	char *cic_str, *alert_str, *text_str;
+	int cic, alert;
+
+	/* Verify has done the test for us */
+	cic_str = strtok_r(cmd->value, ",", &saveptr);
+	alert_str = strtok_r(NULL, ",", &saveptr);
+	text_str = strtok_r(NULL, ",", &saveptr);
+
+	if (!cic_str || !alert_str || !text_str) {
+		cmd->reply = "Programming issue. How did this pass verify?";
+		return CTRL_CMD_ERROR;
+	}
+
+	cmd->reply = "No connection found";
+
+	cic = atoi(cic_str);
+	alert = atoi(alert_str);
+
+	net = cmd->node;
+	llist_for_each_entry(conn, bsc_api_sub_connections(net), entry) {
+		if (!conn->sccp_con)
+			continue;
+
+		if (conn->sccp_con->cic != cic)
+			continue;
+
+		/*
+		 * This is a hack. My E71 does not like to immediately
+		 * receive a release complete on a TCH. So schedule a
+		 * release complete to clear any previous attempt. The
+		 * right thing would be to track invokeId and only send
+		 * the release complete when we get a returnResultLast
+		 * for this invoke id.
+		 */
+		gsm0480_send_releaseComplete(conn);
+		gsm0480_send_ussdNotify(conn, alert, text_str);
+		cmd->reply = "Found a connection";
+		break;
+	}
+
+	return CTRL_CMD_REPLY;
+}
+
+static int verify_net_ussd_notify(struct ctrl_cmd *cmd, const char *value, void *data)
+{
+	char *saveptr = NULL;
+	char *inp, *cic, *alert, *text;
+
+	inp = talloc_strdup(cmd, value);
+
+	cic = strtok_r(inp, ",", &saveptr);
+	alert = strtok_r(NULL, ",", &saveptr);
+	text = strtok_r(NULL, ",", &saveptr);
+
+	talloc_free(inp);
+	if (!cic || !alert || !text)
+		return 1;
+	return 0;
+}
+
 static int msc_signal_handler(unsigned int subsys, unsigned int signal,
 			void *handler_data, void *signal_data)
 {
@@ -687,6 +760,9 @@ int bsc_ctrl_cmds_install(struct gsm_network *net)
 	if (rc)
 		goto end;
 	rc = ctrl_cmd_install(CTRL_NODE_ROOT, &cmd_net_inform_msc);
+	if (rc)
+		goto end;
+	rc = ctrl_cmd_install(CTRL_NODE_ROOT, &cmd_net_ussd_notify);
 	if (rc)
 		goto end;
 	rc = osmo_signal_register_handler(SS_L_INPUT, &bts_connection_status_trap_cb, net);