dnstap reader: add API to free the frame

src/dnstap/reader.c

@@ -92,3 +92,13 @@ int dt_reader_read(dt_reader_t *reader, Dnstap__Dnstap **d)
 
 	return KNOT_EOK;
 }
+
+void dt_reader_free_frame(dt_reader_t *reader, Dnstap__Dnstap **frame_ptr)
+{
+	if (!*frame_ptr) {
+		return;
+	}
+
+	dnstap__dnstap__free_unpacked(*frame_ptr, NULL);
+	*frame_ptr = NULL;
+}

src/dnstap/reader.h

@@ -72,6 +72,14 @@ int dt_reader_free(dt_reader_t *reader);
  */
 int dt_reader_read(dt_reader_t *reader, Dnstap__Dnstap **d);
 
+/*!
+ * \brief free the frame allocated by dt_read_data.
+ *
+ * \param reader                Dnstap reader context.
+ * \param d                     The frame to be freed.
+ */
+void dt_reader_free_frame(dt_reader_t *reader, Dnstap__Dnstap **d);
+
 #endif // _DNSTAP__DNSTAP_H_
 
 /*! @} */