in_mqtt: added buffer size setting and fixed a leak

plugins/in_mqtt/mqtt.c

@@ -144,6 +144,11 @@ static struct flb_config_map config_map[] = {
      0, FLB_TRUE, offsetof(struct flb_in_mqtt_config, payload_key),
      "Key where the payload will be preserved"
     },
+    {
+     FLB_CONFIG_MAP_SIZE, "buffer_size", MQTT_CONNECTION_DEFAULT_BUFFER_SIZE,
+     0, FLB_TRUE, offsetof(struct flb_in_mqtt_config, buffer_size),
+     "Maximum payload size"
+    },
     /* EOF */	
     {0}	
 };

plugins/in_mqtt/mqtt.h

@@ -30,7 +30,8 @@ struct flb_in_mqtt_config {
     char *tcp_port;                    /* TCP Port                    */
 
     flb_sds_t payload_key;             /* payload key */
-
+    size_t buffer_size;                /* connection buffer size      */
+
     int msgp_len;                      /* msgpack data length         */
     char msgp[MQTT_MSGP_BUF_SIZE];     /* msgpack static buffer       */
     struct flb_input_instance *ins;    /* plugin input instance       */

plugins/in_mqtt/mqtt_conn.c

@@ -48,7 +48,7 @@ int mqtt_conn_event(void *data)
     event = &connection->event;
 
     if (event->mask & MK_EVENT_READ) {
-        available = sizeof(conn->buf) - conn->buf_len;
+        available = conn->buf_size - conn->buf_len;
 
         bytes = flb_io_net_read(connection,
                                 (void *) &conn->buf[conn->buf_len],
@@ -93,6 +93,16 @@ struct mqtt_conn *mqtt_conn_add(struct flb_connection *connection,
         return NULL;
     }
 
+    conn->buf = flb_calloc(ctx->buffer_size, 1);
+
+    if (conn->buf == NULL) {
+        flb_errno();
+        flb_free(conn);
+        return NULL;
+    }
+
+    conn->buf_size = ctx->buffer_size;
+
     conn->connection = connection;
 
     /* Set data for the event-loop */
@@ -137,6 +147,10 @@ int mqtt_conn_del(struct mqtt_conn *conn)
     /* Release resources */
     mk_list_del(&conn->_head);
 
+    if (conn->buf != NULL) {
+        flb_free(conn->buf);
+    }
+
     flb_free(conn);
 
     return 0;

plugins/in_mqtt/mqtt_conn.h

@@ -22,6 +22,8 @@
 
 #include <fluent-bit/flb_connection.h>
 
+#define MQTT_CONNECTION_DEFAULT_BUFFER_SIZE "2048"
+
 enum {
     MQTT_NEW        = 1,  /* it's a new connection                */
     MQTT_CONNECTED  = 2,  /* MQTT connection per protocol spec OK */
@@ -36,7 +38,8 @@ struct mqtt_conn {
     int  buf_frame_end;              /* Frame end position                */
     int  buf_pos;                    /* Index position                    */
     int  buf_len;                    /* Buffer content length             */
-    unsigned char buf[1024];         /* Buffer data                       */
+    size_t  buf_size;                /* Buffer size                       */
+    unsigned char *buf;              /* Buffer data                       */
     struct flb_in_mqtt_config *ctx;  /* Plugin configuration context      */
     struct flb_connection *connection;
     struct mk_list _head;            /* Link to flb_in_mqtt_config->conns */

plugins/in_mqtt/mqtt_prot.c

@@ -148,11 +148,13 @@ static int mqtt_data_append(char *topic, size_t topic_len,
     msgpack_unpacked_init(&result);
     if (msgpack_unpack_next(&result, pack, out, &off) != MSGPACK_UNPACK_SUCCESS) {
         msgpack_unpacked_destroy(&result);
+        flb_free(pack);
         return -1;
     }
 
     if (result.data.type != MSGPACK_OBJECT_MAP){
         msgpack_unpacked_destroy(&result);
+        flb_free(pack);
         return -1;
     }
     root = result.data;