Section 3 · Library functions

sockaddr_storage.3type

Package: man-pages

sockaddr

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
STANDARDS
HISTORY
NOTES
SEE ALSO

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>.