sockaddr(3type) sockaddr(3type)
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 inte-
ger 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 ad-
dress, 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), getsock-
opt(2), sendto(2), setsockopt(2), socket(2), socketpair(2), getad-
drinfo(3), gethostbyaddr(3), getnameinfo(3), htonl(3), ipv6(7),
socket(7)
Linux man-pages 6.9.1 2024-05-02 sockaddr(3type)
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