miracled: implement Start/StopScan

Both dbus commands allow external programs to make our device discoverable
for P2P devices and also start scanning for remote devices.

The commands are *not* ref-counted right now, so parallel use is
discouraged. However, these commands can interrupt normal operations on a
wifi-device anyway, so if used in parallel, it is very like to break.
Thus, keep the interface simple and require callers to do
access-management (it's root-only, anyway..).

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

src/miracled-dbus.c

@@ -332,13 +332,24 @@ void peer_dbus_removed(struct peer *p)
 static int link_dbus_start_scan(sd_bus *bus, sd_bus_message *msg,
 				void *data, sd_bus_error *err)
 {
-	return -EINVAL;
+	struct link *l = data;
+	int r;
+
+	r = link_start_scan(l);
+	if (r < 0)
+		return r;
+
+	return sd_bus_reply_method_return(msg, NULL);
 }
 
 static int link_dbus_stop_scan(sd_bus *bus, sd_bus_message *msg,
 			       void *data, sd_bus_error *err)
 {
-	return -EINVAL;
+	struct link *l = data;
+
+	link_stop_scan(l);
+
+	return sd_bus_reply_method_return(msg, NULL);
 }
 
 static int link_dbus_get_type(sd_bus *bus,

src/miracled-link.c

@@ -307,3 +307,29 @@ int link_set_friendly_name(struct link *l, const char *name)
 
 	return 0;
 }
+
+int link_start_scan(struct link *l)
+{
+	if (!l)
+		return -EINVAL;
+
+	switch (l->type) {
+	case LINK_VIRTUAL:
+		return -EOPNOTSUPP;
+	case LINK_WIFI:
+		return wifi_set_discoverable(l->w, true);
+	}
+
+	return -EINVAL;
+}
+
+void link_stop_scan(struct link *l)
+{
+	if (!l)
+		return;
+
+	switch (l->type) {
+	case LINK_WIFI:
+		wifi_set_discoverable(l->w, false);
+	}
+}

src/miracled.h

@@ -108,6 +108,9 @@ void link_free(struct link *l);
 
 int link_set_friendly_name(struct link *l, const char *name);
 
+int link_start_scan(struct link *l);
+void link_stop_scan(struct link *l);
+
 /* manager */
 
 struct manager {