Allow driver and ctrl_interface parameters to be overridden

New wpa_supplicant command line options -o<driver> and -O<ctrl> can
now be used to override the parameters received in add interface
command from dbus or global ctrl_interface. This can be used, e.g.,
to enable control interface when using NetworkManager (add
-O/var/run/wpa_supplicant into the Exec parameter in
/usr/share/dbus-1/system-services/fi.epitest.hostap.WPASupplicant.service).
Similarly, this can be used to use another driver wrapper with
NetworkManager (e.g., -onl80211 to replace WEXT with nl80211).

wpa_supplicant/main.c

@@ -34,6 +34,7 @@ static void usage(void)
 	       "        -i<ifname> -c<config file> [-C<ctrl>] [-D<driver>] "
 	       "[-p<driver_param>] \\\n"
 	       "        [-b<br_ifname>] [-f<debug file>] \\\n"
+	       "        [-o<override driver>] [-O<override ctrl>] \\\n"
 	       "        [-N -i<ifname> -c<conf> [-C<ctrl>] "
 	       "[-D<driver>] \\\n"
 	       "        [-p<driver_param>] [-b<br_ifname>] ...]\n"
@@ -67,6 +68,8 @@ static void usage(void)
 	printf("  -t = include timestamp in debug messages\n"
 	       "  -h = show this help text\n"
 	       "  -L = show license (GPL and BSD)\n"
+	       "  -o = override driver parameter for new interfaces\n"
+	       "  -O = override ctrl_interface parameter for new interfaces\n"
 	       "  -p = driver parameters\n"
 	       "  -P = PID file\n"
 	       "  -q = decrease debugging verbosity (-qq even less)\n");
@@ -140,7 +143,7 @@ int main(int argc, char *argv[])
 	wpa_supplicant_fd_workaround();
 
 	for (;;) {
-		c = getopt(argc, argv, "b:Bc:C:D:df:g:hi:KLNp:P:qstuvW");
+		c = getopt(argc, argv, "b:Bc:C:D:df:g:hi:KLNo:O:p:P:qstuvW");
 		if (c < 0)
 			break;
 		switch (c) {
@@ -191,6 +194,12 @@ int main(int argc, char *argv[])
 			license();
 			exitcode = 0;
 			goto out;
+		case 'o':
+			params.override_driver = optarg;
+			break;
+		case 'O':
+			params.override_ctrl_interface = optarg;
+			break;
 		case 'p':
 			iface->driver_param = optarg;
 			break;

wpa_supplicant/wpa_supplicant.c

@@ -2246,6 +2246,7 @@ struct wpa_supplicant * wpa_supplicant_add_iface(struct wpa_global *global,
 						 struct wpa_interface *iface)
 {
 	struct wpa_supplicant *wpa_s;
+	struct wpa_interface t_iface;
 
 	if (global == NULL || iface == NULL)
 		return NULL;
@@ -2254,7 +2255,22 @@ struct wpa_supplicant * wpa_supplicant_add_iface(struct wpa_global *global,
 	if (wpa_s == NULL)
 		return NULL;
 
-	if (wpa_supplicant_init_iface(wpa_s, iface)) {
+	t_iface = *iface;
+	if (global->params.override_driver) {
+		wpa_printf(MSG_DEBUG, "Override interface parameter: driver "
+			   "('%s' -> '%s')",
+			   iface->driver, global->params.override_driver);
+		t_iface.driver = global->params.override_driver;
+	}
+	if (global->params.override_ctrl_interface) {
+		wpa_printf(MSG_DEBUG, "Override interface parameter: "
+			   "ctrl_interface ('%s' -> '%s')",
+			   iface->ctrl_interface,
+			   global->params.override_ctrl_interface);
+		t_iface.ctrl_interface =
+			global->params.override_ctrl_interface;
+	}
+	if (wpa_supplicant_init_iface(wpa_s, &t_iface)) {
 		wpa_printf(MSG_DEBUG, "Failed to add interface %s",
 			   iface->ifname);
 		wpa_supplicant_deinit_iface(wpa_s);
@@ -2388,6 +2404,12 @@ struct wpa_global * wpa_supplicant_init(struct wpa_params *params)
 	if (params->ctrl_interface)
 		global->params.ctrl_interface =
 			os_strdup(params->ctrl_interface);
+	if (params->override_driver)
+		global->params.override_driver =
+			os_strdup(params->override_driver);
+	if (params->override_ctrl_interface)
+		global->params.override_ctrl_interface =
+			os_strdup(params->override_ctrl_interface);
 	wpa_debug_level = global->params.wpa_debug_level =
 		params->wpa_debug_level;
 	wpa_debug_show_keys = global->params.wpa_debug_show_keys =
@@ -2514,6 +2536,8 @@ void wpa_supplicant_deinit(struct wpa_global *global)
 		os_free(global->params.pid_file);
 	}
 	os_free(global->params.ctrl_interface);
+	os_free(global->params.override_driver);
+	os_free(global->params.override_ctrl_interface);
 
 	os_free(global);
 	wpa_debug_close_syslog();

wpa_supplicant/wpa_supplicant_i.h

@@ -160,6 +160,24 @@ struct wpa_params {
 	 * wpa_debug_syslog - Enable log output through syslog
 	 */
 	int wpa_debug_syslog;
+
+	/**
+	 * override_driver - Optional driver parameter override
+	 *
+	 * This parameter can be used to override the driver parameter in
+	 * dynamic interface addition to force a specific driver wrapper to be
+	 * used instead.
+	 */
+	char *override_driver;
+
+	/**
+	 * override_ctrl_interface - Optional ctrl_interface override
+	 *
+	 * This parameter can be used to override the ctrl_interface parameter
+	 * in dynamic interface addition to force a control interface to be
+	 * created.
+	 */
+	char *override_ctrl_interface;
 };
 
 /**