[6/9] station: add Affinities DBus property

Commit Message

James Prestwood Aug. 13, 2024, 3:56 p.m. UTC

This property will hold an array of object paths for
BasicServiceSet (BSS) objects. For the purpose of this patch
only the setter/getter and client watch is implemented. The
purpose of this array is to guide or loosly lock IWD to certain
BSS's provided that some external client has more information
about the environment than what IWD takes into account for its
roaming decisions. For example:

 - If the device is stationary an external client could reduce
   the likelihood of roaming by setting the affinity to the
   current BSS.
 - If an external client has knowledge of the devices planned
   route though the environment it could plan a path to roam
   between particular APs to reduce and optimize roaming.
---
 src/station.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)

Patch

diff --git a/src/station.c b/src/station.c
index 3b61f264..75dd13bb 100644
--- a/src/station.c
+++ b/src/station.c
@@ -128,6 +128,10 @@  struct station {
 
 	uint64_t last_roam_scan;
 
+	char **affinities;
+	unsigned int affinity_watch;
+	char *affinity_client;
+
 	bool preparing_roam : 1;
 	bool roam_scan_full : 1;
 	bool signal_low : 1;
@@ -1685,6 +1689,13 @@  static void station_enter_state(struct station *station,
 		station_set_evict_nocarrier(station, true);
 		station_set_drop_neighbor_discovery(station, false);
 		station_set_drop_unicast_l2_multicast(station, false);
+
+		if (station->affinity_watch) {
+			l_dbus_remove_watch(dbus_get_bus(),
+						station->affinity_watch);
+			station->affinity_watch = 0;
+		}
+
 		break;
 	case STATION_STATE_DISCONNECTING:
 	case STATION_STATE_NETCONFIG:
@@ -4463,6 +4474,112 @@  static bool station_property_get_state(struct l_dbus *dbus,
 	return true;
 }
 
+static bool station_property_get_affinities(struct l_dbus *dbus,
+					struct l_dbus_message *message,
+					struct l_dbus_message_builder *builder,
+					void *user_data)
+{
+	struct station *station = user_data;
+	char **path = station->affinities;
+
+	if (!station->connected_network)
+		return false;
+
+	l_dbus_message_builder_enter_array(builder, "o");
+
+	while (path && *path) {
+		l_dbus_message_builder_append_basic(builder, 'o', *path);
+		path++;
+	}
+
+	l_dbus_message_builder_leave_array(builder);
+
+	return true;
+}
+
+static void station_affinity_disconnected_cb(struct l_dbus *dbus,
+						void *user_data)
+{
+	struct station *station = user_data;
+
+	l_dbus_remove_watch(dbus_get_bus(), station->affinity_watch);
+	station->affinity_watch = 0;
+
+	l_debug("client that set affinity has disconnected");
+}
+
+static void station_affinity_watch_destroy(void *user_data)
+{
+	struct station *station = user_data;
+
+	l_free(station->affinity_client);
+	station->affinity_client = NULL;
+
+	l_strv_free(station->affinities);
+	station->affinities = NULL;
+}
+
+static struct l_dbus_message *station_property_set_affinities(
+					struct l_dbus *dbus,
+					struct l_dbus_message *message,
+					struct l_dbus_message_iter *new_value,
+					l_dbus_property_complete_cb_t complete,
+					void *user_data)
+{
+	struct station *station = user_data;
+	struct l_dbus_message_iter array;
+	const char *sender = l_dbus_message_get_sender(message);
+	const char *path;
+	char **new_affinities;
+
+	if (!station->connected_network)
+		return dbus_error_not_connected(message);
+
+	if (!station->affinity_watch) {
+		station->affinity_client = l_strdup(sender);
+		station->affinity_watch = l_dbus_add_disconnect_watch(dbus,
+					sender,
+					station_affinity_disconnected_cb,
+					station,
+					station_affinity_watch_destroy);
+	} else if (strcmp(station->affinity_client, sender)) {
+		l_warn("Only one client may manage Affinities property");
+		return dbus_error_not_available(message);
+	}
+
+	if (!l_dbus_message_iter_get_variant(new_value, "ao", &array))
+		return dbus_error_invalid_args(message);
+
+	new_affinities = l_strv_new();
+
+	while (l_dbus_message_iter_next_entry(&array, &path)) {
+		const char *p = network_get_path(station->connected_network);
+
+		/*
+		 * It can't be assumed that the specific BSS has been seen, but
+		 * at least validate the device/network portion matches the
+		 * connected network.
+		 */
+		if (strncmp(p, path, strlen(p))) {
+			l_warn("Can't set affinity to BSS (%s)", path);
+			l_strv_free(new_affinities);
+			return dbus_error_invalid_args(message);
+		}
+
+		new_affinities = l_strv_append(new_affinities, path);
+	}
+
+	l_strv_free(station->affinities);
+	station->affinities = new_affinities;
+
+	l_dbus_property_changed(dbus, netdev_get_path(station->netdev),
+				IWD_STATION_INTERFACE, "Affinities");
+
+	complete(dbus, message, NULL);
+
+	return NULL;
+}
+
 void station_foreach(station_foreach_func_t func, void *user_data)
 {
 	const struct l_queue_entry *entry;
@@ -4693,6 +4810,7 @@  static struct station *station_create(struct netdev *netdev)
 	station_set_autoconnect(station, autoconnect);
 
 	station->roam_bss_list = l_queue_new();
+	station->affinities = l_strv_new();
 
 	return station;
 }
@@ -4785,6 +4903,9 @@  static void station_free(struct station *station)
 
 	l_queue_destroy(station->roam_bss_list, l_free);
 
+	if (station->affinity_watch)
+		l_dbus_remove_watch(dbus_get_bus(), station->affinity_watch);
+
 	l_free(station);
 }
 
@@ -4821,6 +4942,9 @@  static void station_setup_interface(struct l_dbus_interface *interface)
 					station_property_get_scanning, NULL);
 	l_dbus_interface_property(interface, "State", 0, "s",
 					station_property_get_state, NULL);
+	l_dbus_interface_property(interface, "Affinities", 0, "ao",
+					station_property_get_affinities,
+					station_property_set_affinities);
 }
 
 static void station_destroy_interface(void *user_data)