NAME

       sockaddr,  sockaddr_storage,  sockaddr_in,  sockaddr_in6, sockaddr_un, socklen_t, in_addr,
       in6_addr, in_addr_t, in_port_t, - socket address

LIBRARY

       Standard C library (libc)

SYNOPSIS

       #include <sys/socket.h>

       struct sockaddr {
           sa_family_t     sa_family;      /* Address family */
           char            sa_data[];      /* Socket address */
       };

       struct sockaddr_storage {
           sa_family_t     ss_family;      /* Address family */
       };

       typedef /* ... */ socklen_t;
       typedef /* ... */ sa_family_t;

   Internet domain sockets
       #include <netinet/in.h>

       struct sockaddr_in {
           sa_family_t     sin_family;     /* AF_INET */
           in_port_t       sin_port;       /* Port number */
           struct in_addr  sin_addr;       /* IPv4 address */
       };

       struct sockaddr_in6 {
           sa_family_t     sin6_family;    /* AF_INET6 */
           in_port_t       sin6_port;      /* Port number */
           uint32_t        sin6_flowinfo;  /* IPv6 flow info */
           struct in6_addr sin6_addr;      /* IPv6 address */
           uint32_t        sin6_scope_id;  /* Set of interfaces for a scope */
       };

       struct in_addr {
           in_addr_t s_addr;
       };

       struct in6_addr {
           uint8_t   s6_addr[16];
       };

       typedef uint32_t in_addr_t;
       typedef uint16_t in_port_t;

   UNIX domain sockets
       #include <sys/un.h>

       struct sockaddr_un {
           sa_family_t     sun_family;     /* Address family */
           char            sun_path[];     /* Socket pathname */
       };

DESCRIPTION

       sockaddr
              Describes a socket address.

       sockaddr_storage
              A structure at least as large as any other  sockaddr_*  address  structures.   It's
              aligned  so  that  a  pointer  to  it  can be cast as a pointer to other sockaddr_*
              structures and used to access its fields.

       socklen_t
              Describes the length of a socket address.  This is an integer type of at  least  32
              bits.

       sa_family_t
              Describes a socket's protocol family.  This is an unsigned integer type.

   Internet domain sockets
       sockaddr_in
              Describes  an  IPv4  Internet  domain  socket  address.   The sin_port and sin_addr
              members are stored in network byte order.

       sockaddr_in6
              Describes an IPv6 Internet domain socket address.  The sin6_addr.s6_addr  array  is
              used to contain a 128-bit IPv6 address, stored in network byte order.

   UNIX domain sockets
       sockaddr_un
              Describes a UNIX domain socket address.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001.

       socklen_t was invented by POSIX.  See also accept(2).

       These  structures  were  invented  before modern ISO C strict-aliasing rules.  If aliasing
       rules are applied strictly, these structures would be extremely difficult to  use  without
       invoking   Undefined   Behavior.    POSIX   Issue  8  will  fix  this  by  requiring  that
       implementations make sure that these structures can be safely used as they were designed.

NOTES

       socklen_t is also defined in <netdb.h>.

       sa_family_t is also defined in <netinet/in.h> and <sys/un.h>.

SEE ALSO

       accept(2), bind(2), connect(2), getpeername(2), getsockname(2), getsockopt(2),  sendto(2),
       setsockopt(2), socket(2), socketpair(2), getaddrinfo(3), gethostbyaddr(3), getnameinfo(3),
       htonl(3), ipv6(7), socket(7)