Interworking: Allow cred blocks not to be saved to a file

The new cred block parameter 'temporary' can be used to indicate that a
cred block is not to be saved to wpa_supplicant configuration file
(e.g., "SET_CRED 0 temporary 1"). This is similar to the concept of
temporary network blocks and allows cred blocks to be managed outside
the wpa_supplicant config file when other parameters are still saved to
the file written by wpa_supplicant.

Signed-hostap: Jouni Malinen <j@w1.fi>

wpa_supplicant/README-HS20

@@ -109,6 +109,8 @@ Credentials can be pre-configured for automatic network selection:
 #
 # credential fields:
 #
+# temporary: Whether this credential is temporary and not to be saved
+#
 # priority: Priority group
 #	By default, all networks and credentials get the same priority group
 #	(0). This field can be used to give higher priority for credentials
@@ -269,6 +271,8 @@ OK
 OK
 > set_cred 0 priority 1
 OK
+> set_cred 0 temporary 1
+OK
 
 Add a SIM credential using a simulated SIM/USIM card for testing:
 

wpa_supplicant/config.c

@@ -2393,6 +2393,11 @@ int wpa_config_set_cred(struct wpa_cred *cred, const char *var,
 	char *val;
 	size_t len;
 
+	if (os_strcmp(var, "temporary") == 0) {
+		cred->temporary = atoi(value);
+		return 0;
+	}
+
 	if (os_strcmp(var, "priority") == 0) {
 		cred->priority = atoi(value);
 		return 0;

wpa_supplicant/config.h

@@ -51,6 +51,11 @@ struct wpa_cred {
 	 */
 	int id;
 
+	/**
+	 * temporary - Whether this credential is temporary and not to be saved
+	 */
+	int temporary;
+
 	/**
 	 * priority - Priority group
 	 *

wpa_supplicant/config_file.c

@@ -1110,6 +1110,8 @@ int wpa_config_write(const char *name, struct wpa_config *config)
 	wpa_config_write_global(f, config);
 
 	for (cred = config->cred; cred; cred = cred->next) {
+		if (cred->temporary)
+			continue;
 		fprintf(f, "\ncred={\n");
 		wpa_config_write_cred(f, cred);
 		fprintf(f, "}\n");

wpa_supplicant/wpa_supplicant.conf

@@ -342,6 +342,8 @@ fast_reauth=1
 #
 # credential fields:
 #
+# temporary: Whether this credential is temporary and not to be saved
+#
 # priority: Priority group
 #	By default, all networks and credentials get the same priority group
 #	(0). This field can be used to give higher priority for credentials