Add extract_metadata to main PDU classes

include/tins/dns.h

@@ -589,6 +589,14 @@ public:
     typedef IPv4Address address_type;
     typedef IPv6Address address_v6_type;
     
+    /**
+     * \brief Extracts metadata for this protocol based on the buffer provided
+     *
+     * \param buffer Pointer to a buffer
+     * \param total_sz Size of the buffer pointed by buffer
+     */
+    static metadata extract_metadata(const uint8_t *buffer, uint32_t total_sz);
+    
     /**
      * \brief Default constructor.
      *