socket.h(3HEAD) Headers socket.h(3HEAD)
NAME
socket.h, 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:
size_t cmsg_len /* data byte count, includ-
ing 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.
SCM_UCRED Indicates that the data array contains a ucred_t to be received. The ucred_t is the credential of the sending process at
the time the message was sent. This is a Sun-specific, Evolving interface. See ucred_get(3C).
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.
CMSG_SPACE(len)
Given the length of an ancillary data object, CMSG_SPACE() returns the space required by the object and its cmsghdr structure, includ-
ing any padding needed to satisfy alignment requirements. This macro can be used, for example, to allocate space dynamically for the
ancillary data. This macro should not be used to initialize the cmsg_len member of a cmsghdr structure. Use the CMSG_LEN() macro
instead.
CMSG_LEN(len)
Given the length of an ancillary data object, CMSG_LEN() returns the value to store in the cmsg_len member of the cmsghdr structure,
taking into account any padding needed to satisfy alignment requirements.
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.
SO_RECVUCRED Request the reception of user credential ancillary data. This is a Sun-specific, Evolving interface. See ucred_get(3C).
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.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
SEE ALSO
accept(3SOCKET), accept(3XNET), bind(3SOCKET), bind(3XNET), connect(3SOCKET), connect(3XNET), getpeername(3SOCKET), getpeername(3XNET),
getpeerucred(3C), getsockname(3SOCKET), getsockname(3XNET), getsockopt(3SOCKET), getsockopt(3XNET), libsocket(3LIB), listen(3SOCKET), lis-
ten(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), shut-
down(3XNET), socket(3SOCKET), socket(3XNET), socketpair(3SOCKET) socketpair(3XNET), ucred_get(3C)attributes(5), standards(5)
SunOS 5.10 11 Aug 2004 socket.h(3HEAD)