dpp-util: add support for 3rd party JSON fields

The DPP spec allows 3rd party fields in the DPP configuration
object (section 4.5.2). IWD can take advantage of this (when
configuring another IWD supplicant) to communicate additional
profile options that may be required for the network.

The new configuration member will be called "/net/connman/iwd"
and will be an object containing settings specific to IWD.
More settings could be added here if needed but for now only
the following are defined:

{
  send_hostname: true/false,
  hidden: true/false
}

These correspond to the following network profile settings:

[IPv4].SendHostname
[Settings].Hidden

src/dpp-util.c

@@ -144,6 +144,40 @@ static uint32_t dpp_parse_akm(char *akms)
 	return akm_out;
 }
 
+static bool dpp_parse_extra_options(struct dpp_configuration *config,
+					struct json_iter *extra)
+{
+	struct json_iter host_val;
+	struct json_iter hidden_val;
+	bool hostname = false;
+	bool hidden = false;
+
+	if (!json_iter_parse(extra,
+			JSON_OPTIONAL("send_hostname", JSON_PRIMITIVE,
+					&host_val),
+			JSON_OPTIONAL("hidden", JSON_PRIMITIVE, &hidden_val),
+			JSON_UNDEFINED))
+		return false;
+
+	/*
+	 * The values are optional in order to support backwards compatibility
+	 * if more are added, but if the key does exist require the type
+	 * matches and fail otherwise.
+	 */
+	if (json_iter_is_valid(&host_val) &&
+			!json_iter_get_boolean(&host_val, &hostname))
+		return false;
+
+	if (json_iter_is_valid(&hidden_val) &&
+			!json_iter_get_boolean(&hidden_val, &hidden))
+		return false;
+
+	config->send_hostname = hostname;
+	config->hidden = hidden;
+
+	return true;
+}
+
 /*
  * TODO: This handles the most basic configuration. i.e. a configuration object
  * with ssid/passphrase/akm.
@@ -156,6 +190,7 @@ struct dpp_configuration *dpp_parse_configuration_object(const char *json,
 	struct json_iter iter;
 	struct json_iter discovery;
 	struct json_iter cred;
+	struct json_iter extra;
 	_auto_(l_free) char *tech = NULL;
 	_auto_(l_free) char *ssid = NULL;
 	_auto_(l_free) char *akm = NULL;
@@ -172,6 +207,7 @@ struct dpp_configuration *dpp_parse_configuration_object(const char *json,
 			JSON_MANDATORY("wi-fi_tech", JSON_STRING, &tech),
 			JSON_MANDATORY("discovery", JSON_OBJECT, &discovery),
 			JSON_MANDATORY("cred", JSON_OBJECT, &cred),
+			JSON_OPTIONAL("/net/connman/iwd", JSON_OBJECT, &extra),
 			JSON_UNDEFINED))
 		goto free_contents;
 
@@ -210,6 +246,11 @@ struct dpp_configuration *dpp_parse_configuration_object(const char *json,
 	if (!config->akm_suites)
 		goto free_config;
 
+	if (json_iter_is_valid(&extra)) {
+		if (!dpp_parse_extra_options(config, &extra))
+			l_warn("Extra settings failed to parse!");
+	}
+
 	json_contents_free(c);
 
 	return config;
@@ -258,10 +299,20 @@ char *dpp_configuration_to_json(struct dpp_configuration *config)
 						config->psk);
 
 	return l_strdup_printf("{\"wi-fi_tech\":\"infra\","
-				"\"discovery\":{\"ssid\":\"%s\"},"
+				"\"discovery\":{"
-				"\"cred\":{\"akm\":\"%s\",%s}}",
+					"\"ssid\":\"%s\""
+				"},"
+				"\"cred\":{"
+					"\"akm\":\"%s\",%s"
+				"},"
+				"\"/net/connman/iwd\":{"
+					"\"send_hostname\":%s,"
+					"\"hidden\":%s}"
+				"}",
 				ssid, dpp_akm_to_string(config->akm_suites),
-				pass_or_psk);
+				pass_or_psk,
+				config->send_hostname ? "true" : "false",
+				config->hidden ? "true" : "false");
 }
 
 struct dpp_configuration *dpp_configuration_new(
@@ -273,6 +324,8 @@ struct dpp_configuration *dpp_configuration_new(
 	_auto_(l_free) char *passphrase = NULL;
 	_auto_(l_free) char *psk = NULL;
 	size_t ssid_len = strlen(ssid);
+	bool send_hostname;
+	bool hidden;
 
 	if (!l_settings_has_group(settings, "Security"))
 		return NULL;
@@ -299,6 +352,16 @@ struct dpp_configuration *dpp_configuration_new(
 
 	config->akm_suites = akm_suite;
 
+	if (!l_settings_get_bool(settings, "IPv4", "SendHostname",
+					&send_hostname))
+		send_hostname = false;
+
+	if (!l_settings_get_bool(settings, "Settings", "Hidden", &hidden))
+		hidden = false;
+
+	config->send_hostname = send_hostname;
+	config->hidden = hidden;
+
 	return config;
 }
 

src/dpp-util.h

@@ -117,6 +117,10 @@ struct dpp_configuration {
 	uint32_t akm_suites;
 	char *passphrase;
 	char *psk;		/* hex string */
+
+	/* "3rd party extensions" only applicable for two IWD peers */
+	bool send_hostname : 1;
+	bool hidden : 1;
 };
 
 struct dpp_configuration *dpp_parse_configuration_object(const char *json,