Issue

This article describes the server side of using IPv6 Extension headers over TCP socket.
The client side is described in article 714913:
How to send IPv6 DSTOPTS extension header with IPv6 Option over TCP socket?

A tcp server wants to get ancillary data attached to incoming packet on IPv6 TCP socket.
The header type should be "Destination options header" IPPROTO_DSTOPTS.
The header should contain one "IPv6 Option" with specific self defined option type and data.

The option, which server wants to get, should carry the structure of a type "dst_opt_tlv_t" defined below:

typedef struct {
    uint16_t port;        
    uint16_t vrf;
    uint8_t  flags;                                         
    uint8_t  reserved[3];
    uint8_t  addr8[16];
} dst_opt_tlv_data_t;

typedef struct {
    uint8_t padn;
    uint8_t len;
    uint8_t data[8];
} dst_opt_tlv_pad_t;

typedef struct {
    dst_opt_tlv_data_t data;
    dst_opt_tlv_pad_t pad;
} dst_opt_tlv_t;