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)