ussd: Be extra pedantic trying to Cancel

If we initiated a Respond() transaction, but have not returned from the
callback.  Or if we already called Cancel and it hasn't returned yet.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/ussd.c b/src/ussd.c
index a2d6cf3b..825d5606 100644
--- a/src/ussd.c
+++ b/src/ussd.c
@@ -554,6 +554,13 @@ static DBusMessage *ussd_cancel(DBusConnection *conn, DBusMessage *msg,
 	if (ussd->state == USSD_STATE_IDLE)
 		return __ofono_error_not_active(msg);
 
+	/* We have called Respond() but not returned from its callback yet */
+	if (ussd->state == USSD_STATE_USER_ACTION && ussd->pending)
+		return __ofono_error_busy(msg);
+
+	if (ussd->cancel)
+		return __ofono_error_busy(msg);
+
 	if (!ussd->driver->cancel)
 		return __ofono_error_not_implemented(msg);