Add property helper functions.

mosquitto_property_identifier()
mosquitto_property_identifier_to_string()
mosquitto_property_next()

ChangeLog.txt

@@ -9,6 +9,12 @@ Client library:
   now expected to be generated on the broker. This matches the behaviour for
   v5 clients. Closes #291.
 - Add support for connecting to brokers through Unix domain sockets.
+- Add `mosquitto_property_identifier()`, for retrieving the identifier integer
+  for a property.
+- Add `mosquitto_property_identifier_to_string()` for converting a property
+  identifier integer to the corresponding property name string.
+- Add `mosquitto_property_next()` to retrieve the next property in a list, for
+  iterating over property lists.
 
 Clients:
 - Add timeout return code (27) for `mosquitto_sub -W <secs>` and

lib/linker.version

@@ -132,3 +132,10 @@ MOSQ_1.6 {
 		mosquitto_void_option;
 		mosquitto_will_set_v5;
 } MOSQ_1.5;
+
+MOSQ_1.7 {
+	global:
+		mosquitto_property_identifier;
+		mosquitto_property_identifier_to_string;
+		mosquitto_property_next;
+} MOSQ_1.6;

lib/mosquitto.h

@@ -2695,6 +2695,44 @@ libmosq_EXPORT int mosquitto_property_add_string(mosquitto_property **proplist,
  */
 libmosq_EXPORT int mosquitto_property_add_string_pair(mosquitto_property **proplist, int identifier, const char *name, const char *value);
 
+
+/*
+ * Function: mosquitto_property_identifier
+ *
+ * Return the property identifier for a single property.
+ *
+ * Parameters:
+ *	property - pointer to a valid mosquitto_property pointer.
+ *
+ * Returns:
+ *  A valid property identifier on success
+ *  0 - on error
+ */
+libmosq_EXPORT int mosquitto_property_identifier(const mosquitto_property *property);
+
+
+/*
+ * Function: mosquitto_property_next
+ *
+ * Return the next property in a property list. Use to iterate over a property
+ * list, e.g.:
+ *
+ * for(prop = proplist; prop != NULL; prop = mosquitto_property_next(prop)){
+ *		if(mosquitto_property_identifier(prop) == MQTT_PROP_CONTENT_TYPE){
+ *			...
+ *		}
+ * }
+ *
+ * Parameters:
+ *	proplist - pointer to mosquitto_property pointer, the list of properties
+ *
+ * Returns:
+ *	Pointer to the next item in the list
+ *	NULL, if proplist is NULL, or if there are no more items in the list.
+ */
+libmosq_EXPORT const mosquitto_property *mosquitto_property_next(const mosquitto_property *proplist);
+
+
 /*
  * Function: mosquitto_property_read_byte
  *
@@ -2965,6 +3003,23 @@ libmosq_EXPORT int mosquitto_property_check_command(int command, int identifier)
  */
 libmosq_EXPORT int mosquitto_property_check_all(int command, const mosquitto_property *properties);
 
+/*
+ * Function: mosquitto_property_identifier_to_string
+ *
+ * Return the property name as a string for a property identifier.
+ * The property name is as defined in the MQTT specification, with - as a
+ * separator, for example: payload-format-indicator.
+ *
+ * Parameters:
+ *	identifier - valid MQTT property identifier integer
+ *
+ * Returns:
+ *  A const string to the property name on success
+ *  NULL on failure
+ */
+libmosq_EXPORT const char *mosquitto_property_identifier_to_string(int identifier);
+
+
 /* Function: mosquitto_string_to_property_info
  *
  * Parse a property name string and convert to a property identifier and data type.

lib/property_mosq.c

@@ -534,6 +534,69 @@ int mosquitto_property_check_command(int command, int identifier)
 }
 
 
+const char *mosquitto_property_identifier_to_string(int identifier)
+{
+	switch(identifier){
+		case MQTT_PROP_PAYLOAD_FORMAT_INDICATOR:
+			return "payload-format-indicator";
+		case MQTT_PROP_MESSAGE_EXPIRY_INTERVAL:
+			return "message-expiry-interval";
+		case MQTT_PROP_CONTENT_TYPE:
+			return "content-type";
+		case MQTT_PROP_RESPONSE_TOPIC:
+			return "response-topic";
+		case MQTT_PROP_CORRELATION_DATA:
+			return "correlation-data";
+		case MQTT_PROP_SUBSCRIPTION_IDENTIFIER:
+			return "subscription-identifier";
+		case MQTT_PROP_SESSION_EXPIRY_INTERVAL:
+			return "session-expiry-interval";
+		case MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER:
+			return "assigned-client-identifier";
+		case MQTT_PROP_SERVER_KEEP_ALIVE:
+			return "server-keep-alive";
+		case MQTT_PROP_AUTHENTICATION_METHOD:
+			return "authentication-method";
+		case MQTT_PROP_AUTHENTICATION_DATA:
+			return "authentication-data";
+		case MQTT_PROP_REQUEST_PROBLEM_INFORMATION:
+			return "request-problem-information";
+		case MQTT_PROP_WILL_DELAY_INTERVAL:
+			return "will-delay-interval";
+		case MQTT_PROP_REQUEST_RESPONSE_INFORMATION:
+			return "request-response-information";
+		case MQTT_PROP_RESPONSE_INFORMATION:
+			return "response-information";
+		case MQTT_PROP_SERVER_REFERENCE:
+			return "server-reference";
+		case MQTT_PROP_REASON_STRING:
+			return "reason-string";
+		case MQTT_PROP_RECEIVE_MAXIMUM:
+			return "receive-maximum";
+		case MQTT_PROP_TOPIC_ALIAS_MAXIMUM:
+			return "topic-alias-maximum";
+		case MQTT_PROP_TOPIC_ALIAS:
+			return "topic-alias";
+		case MQTT_PROP_MAXIMUM_QOS:
+			return "maximum-qos";
+		case MQTT_PROP_RETAIN_AVAILABLE:
+			return "retain-available";
+		case MQTT_PROP_USER_PROPERTY:
+			return "user-property";
+		case MQTT_PROP_MAXIMUM_PACKET_SIZE:
+			return "maximum-packet-size";
+		case MQTT_PROP_WILDCARD_SUB_AVAILABLE:
+			return "wildcard-subscription-available";
+		case MQTT_PROP_SUBSCRIPTION_ID_AVAILABLE:
+			return "subscription-identifier-available";
+		case MQTT_PROP_SHARED_SUB_AVAILABLE:
+			return "shared-subscription-available";
+		default:
+			return NULL;
+	}
+}
+
+
 int mosquitto_string_to_property_info(const char *propname, int *identifier, int *type)
 {
 	if(!propname) return MOSQ_ERR_INVAL;
@@ -926,6 +989,22 @@ const mosquitto_property *property__get_property(const mosquitto_property *propl
 }
 
 
+int mosquitto_property_identifier(const mosquitto_property *property)
+{
+	if(property == NULL) return 0;
+
+	return property->identifier;
+}
+
+
+const mosquitto_property *mosquitto_property_next(const mosquitto_property *proplist)
+{
+	if(proplist == NULL) return NULL;
+
+	return proplist->next;
+}
+
+
 const mosquitto_property *mosquitto_property_read_byte(const mosquitto_property *proplist, int identifier, uint8_t *value, bool skip_first)
 {
 	const mosquitto_property *p;