Add callback to mqtt_list_subscribe_topic

This will allow user to use the information as per application
requirement. passing handler as NULL will have same behaviour as
previous API.

Signed-off-by: Ajay Bhargav <[email protected]>

Author: ajaybhargav

mqttclient/mqttclient.c

@@ -1468,8 +1468,7 @@ int mqtt_publish(mqtt_client_t* c, const char* topic_filter, mqtt_message_t* msg
     RETURN_ERROR(rc);
 }
 
-
-int mqtt_list_subscribe_topic(mqtt_client_t* c)
+int mqtt_list_subscribe_topic(mqtt_client_t* c, topiclist_hanndler_t handler)
 {
     int i = 0;
 
@@ -1488,6 +1487,8 @@ int mqtt_list_subscribe_topic(mqtt_client_t* c)
         /* determine whether a node already exists by mqtt topic, but wildcards are not supported */
         if (NULL != msg_handler->topic_filter) {
             MQTT_LOG_I("mqtt-client:%d %s() -[%d] subscribe topic: %s", __LINE__, __FUNCTION__, ++i ,msg_handler->topic_filter);
+            if (handler)
+                handler(msg_handler->topic_filter, msg_handler->qos);
         }
     }
 

mqttclient/mqttclient.h

@@ -65,6 +65,7 @@ typedef struct message_data {
 typedef void (*interceptor_handler_t)(void* client, message_data_t* msg);
 typedef void (*message_handler_t)(void* client, message_data_t* msg);
 typedef void (*reconnect_handler_t)(void* client, void* reconnect_date);
+typedef void (*topiclist_hanndler_t)(const char *topicname, mqtt_qos_t qos);
 
 typedef struct message_handlers {
     mqtt_list_t         list;
@@ -170,7 +171,7 @@ int mqtt_keep_alive(mqtt_client_t* c);
 int mqtt_subscribe(mqtt_client_t* c, const char* topic_filter, mqtt_qos_t qos, message_handler_t msg_handler);
 int mqtt_unsubscribe(mqtt_client_t* c, const char* topic_filter);
 int mqtt_publish(mqtt_client_t* c, const char* topic_filter, mqtt_message_t* msg);
-int mqtt_list_subscribe_topic(mqtt_client_t* c);
+int mqtt_list_subscribe_topic(mqtt_client_t* c, topiclist_hanndler_t handler);
 int mqtt_set_will_options(mqtt_client_t* c, char *topic, mqtt_qos_t qos, uint8_t retained, char *message);
 
 #ifdef __cplusplus