Suggestions on how to customize the metadata fields of each packet

Hi all,

In the project I am working I need to define custom metadata fields on each
packet once they are captured using DPDK.
I have seen that each packet has a headroom memory space (128 bytes long)
where RSS hashing and other metadata provided by the NIC is stored. This
information will be useful for me but I need to add some further fields to
these metadata without having to modify the source code of the library.

Do you which is the best practice to do it? Do I have for example to define
a struct that contains rte_mbuf struct and additional metadata struct?

struct new_packet{

struct rte_mbuf;
struct additional_metadata

}

I would appreciate it if you could provide me with some guidelines to know
how to implement it.

Thanks a lot

-- 
Victor