socket struct header

#include  or 

struct ifreq
{
#define IFHWADDRLEN     6
       union
       {
               char    ifrn_name[IFNAMSIZ];            /* if name, e.g. "en0" */
       } ifr_ifrn;

       union {
               struct  sockaddr ifru_addr;
               struct  sockaddr ifru_dstaddr;
               struct  sockaddr ifru_broadaddr;
               struct  sockaddr ifru_netmask;
               struct  sockaddr ifru_hwaddr;
               short   ifru_flags;
               int     ifru_ivalue;
               int     ifru_mtu;
               struct  ifmap ifru_map;
               char    ifru_slave[IFNAMSIZ];   /* Just fits the size */
               char    ifru_newname[IFNAMSIZ];
               void __user *   ifru_data;
               struct  if_settings ifru_settings;
       } ifr_ifru;
};

#define ifr_name        ifr_ifrn.ifrn_name      /* interface name       */
#define ifr_hwaddr      ifr_ifru.ifru_hwaddr    /* MAC address          */
#define ifr_addr        ifr_ifru.ifru_addr      /* address              */
#define ifr_dstaddr     ifr_ifru.ifru_dstaddr   /* other end of p-p lnk */
#define ifr_broadaddr   ifr_ifru.ifru_broadaddr /* broadcast address    */
#define ifr_netmask     ifr_ifru.ifru_netmask   /* interface net mask   */
#define ifr_flags       ifr_ifru.ifru_flags     /* flags                */
#define ifr_metric      ifr_ifru.ifru_ivalue    /* metric               */
#define ifr_mtu         ifr_ifru.ifru_mtu       /* mtu                  */
#define ifr_map         ifr_ifru.ifru_map       /* device map           */
#define ifr_slave       ifr_ifru.ifru_slave     /* slave device         */
#define ifr_data        ifr_ifru.ifru_data      /* for use by interface */
#define ifr_ifindex     ifr_ifru.ifru_ivalue    /* interface index      */
#define ifr_bandwidth   ifr_ifru.ifru_ivalue    /* link bandwidth       */
#define ifr_qlen        ifr_ifru.ifru_ivalue    /* Queue length         */
#define ifr_newname     ifr_ifru.ifru_newname   /* New name             */
#define ifr_settings    ifr_ifru.ifru_settings  /* Device/proto settings*/


----------------------------------------------------------------------------

linux/socket.h
struct sockaddr {
        sa_family_t     sa_family;      /* address family, AF_xxx       */
        char            sa_data[14];    /* 14 bytes of protocol address */
};

An IPv4 socket address strcuture

#include inux/in.h

struct in_addr{

in_addr_t s_addr;

};

#include inux/in.h

struct sockaddr_in{

uint8_t sin_len;

sa_family_t sin_family;

in_port_t sin_port;

struct in_addr sin_addr;

char sin_zero[8];

};

An IPv6 socket address structure

struct in6_addr{

uint8_t s6_addr[16];

};

#define SIN6_LEN

struct sockaddr_in6{

uint8_t sin6_len;

sa_family_t sin6_family;

in_port_t sin6_port;

uint32_t sin6_flowinfo;

struct in6_addr sin6_addr;

uint32_t sin6_scope_id;

};