socket(3HEAD)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO

NAME

socket- Internet Protocol family

SYNOPSIS

#include <sys/socket.h>

DESCRIPTION

The <sys/socket.h> header defines the unsigned integral type sa_family_t through typedef.

The <sys/socket.h> header defines the sockaddr structure that includes the following members:

---

sa_family_t	sa_family	/* address family */
char	sa_data[ ]	/* socket address (variable-length data) */

---

The <sys/socket.h> header defines the msghdr structure that includes the following members:

void	*msg_name	/* optional address */
size_t	msg_namelen	/* size of address */
struct iovec	*msg_iov	/* scatter/gather array */
int	msg_iovlen	/* members in msg_iov */
void	*msg_control	/* ancillary data, see below */
size_t	msg_controllen	/* ancillary data buffer len */
int	msg_flags	/* flags on received message */

The <sys/socket.h> header defines the cmsghdr structure that includes the following members:

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size_t	cmsg_len	/* data byte count, including hdr */
int	cmsg_level	/* originating protocol */
int	cmsg_type	/* protocol-specific type */

---

Ancillary data consists of a sequence of pairs, each consisting of a cmsghdr structure followed by a data array. The data array contains the ancillary data message, and the cmsghdr structure contains descriptive information that allows an application to correctly parse the data.

The values for cmsg_level will be legal values for the level argument to the getsockopt() and setsockopt() functions. The SCM_RIGHTS type is supported for level SOL_SOCKET.

Ancillary data is also possible at the socket level. The <sys/socket.h> header defines the following macro for use as the cmsg_type value when cmsg_level is SOL_SOCKET:

SCM_RIGHTS

Indicates that the data array contains the access rights to be sent or received.

The <sys/socket.h> header defines the following macros to gain access to the data arrays in the ancillary data associated with a message header:

CMSG_DATA(cmsg)

If the argument is a pointer to a cmsghdr structure, this macro returns an unsigned character pointer to the data array associated with the cmsghdr structure.

CMSG_NXTHDR(mhdr,cmsg)

If the first argument is a pointer to a msghdr structure and the second argument is a pointer to a cmsghdr structure in the ancillary data, pointed to by the msg_control field of that msghdr structure, this macro returns a pointer to the next cmsghdr structure, or a null pointer if this structure is the last cmsghdr in the ancillary data.

CMSG_FIRSTHDR(mhdr)

If the argument is a pointer to a msghdr structure, this macro returns a pointer to the first cmsghdr structure in the ancillary data associated with this msghdr structure, or a null pointer if there is no ancillary data associated with the msghdr structure.

The <sys/socket.h> header defines the linger structure that includes the following members:

int	l_onoff	/* indicates whether linger option is enabled */
int	l_linger	/* linger time, in seconds */

The <sys/socket.h> header defines the following macros:

SOCK_DGRAM

Datagram socket

SOCK_STREAM

Byte-stream socket

SOCK_SEQPACKET

Sequenced-packet socket

The <sys/socket.h> header defines the following macro for use as the level argument of setsockopt() and getsockopt().

SOL_SOCKET

Options to be accessed at socket level, not protocol level.

The <sys/socket.h> header defines the following macros: for use as the option_name argument in getsockopt() or setsockopt() calls:

SO_DEBUG

Debugging information is being recorded.

SO_ACCEPTCONN

Socket is accepting connections.

SO_BROADCAST

Transmission of broadcast messages is supported.

SO_REUSEADDR

Reuse of local addresses is supported.

SO_KEEPALIVE

Connections are kept alive with periodic messages.

SO_LINGER

Socket lingers on close.

SO_OOBINLINE

Out-of-band data is transmitted in line.

SO_SNDBUF

Send buffer size.

SO_RCVBUF

Receive buffer size.

SO_ERROR

Socket error status.

SO_TYPE

Socket type.

The <sys/socket.h> header defines the following macros for use as the valid values for the msg_flags field in the msghdr structure, or the flags parameter in recvfrom(), recvmsg(), sendto(), or sendmsg() calls:

MSG_CTRUNC

Control data truncated.

MSG_EOR

Terminates a record (if supported by the protocol).

MSG_OOB

Out-of-band data.

MSG_PEEK

Leave received data in queue.

MSG_TRUNC

Normal data truncated.

MSG_WAITALL

Wait for complete message.

The <sys/socket.h> header defines the following macros:

AF_UNIX

UNIX domain sockets

AF_INET

Internet domain sockets

The <sys/socket.h> header defines the following macros:

SHUT_RD

Disables further receive operations.

SHUT_WR

Disables further send operations.

SHUT_RDWR

Disables further send and receive operations.

The following are declared as functions, and may also be defined as macros:

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int accept(int socket, struct sockaddr *address, size_t *address_len);

int bind(int socket, const struct sockaddr *address, size_t address_len);

int connect(int socket, const struct sockaddr *address, size_t address_len);

int getpeername(int socket, struct sockaddr *address, size_t *address_len);

int getsockname(int socket, struct sockaddr *address, size_t *address_len);

int getsockopt(int socket, int level, int option_name, void *option_value, size_t *option_len);

int listen(int socket, int backlog);

ssize_t recv(int socket, void *buffer, size_t length, int flags);

ssize_t recvfrom(int socket, void *buffer, size_t length, int flags, struct sockaddr *address, size_t *address_len);

ssize_t recvmsg(int socket, struct msghdr *message, int flags);

ssize_t send(int socket, const void *message, size_t length, int flags);

ssize_t sendmsg(int socket, const struct msghdr *message, int flags);

ssize_t sendto(int socket, const void *message, size_t length, int flags, const struct sockaddr *dest_addr, size_t dest_len);

int setsockopt(int socket, int level, int option_name, const void *option_value, size_t option_len);

int shutdown(int socket, int how);

int socket(int domain, int type, int protocol);

int socketpair(int domain, int type, int protocol, int socket_vector[2]);

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SEE ALSO

accept(3SOCKET), accept(3XNET), bind(3SOCKET), bind(3XNET), connect(3SOCKET), connect(3XNET), getpeername(3SOCKET), getpeername(3XNET), getsockname(3SOCKET), getsockname(3XNET), getsockopt(3SOCKET), getsockopt(3XNET), listen(3SOCKET), listen(3XNET), recv(3SOCKET), recv(3XNET), recvfrom(3SOCKET), recvfrom(3XNET), recvmsg(3SOCKET), recvmsg(3XNET), send(3SOCKET), send(3XNET), sendmsg(3SOCKET), sendmsg(3XNET), sendto(3SOCKET), sendto(3XNET), setsockopt(3SOCKET), setsockopt(3XNET), shutdown(3SOCKET), shutdown(3XNET), socket(3SOCKET), socket(3XNET), socketpair(3SOCKET) socketpair(3XNET)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO