NAME
sockaddr, sockaddr_storage, socklen_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;
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
See sockaddr_in(3type) and sockaddr_in6(3type).
UNIX domain sockets
See sockaddr_un(3type).
STANDARDS
POSIX.1-2024.
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.1-2024 fixed 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)