SOCKET.H(3HEAD) Headers SOCKET.H(3HEAD)


NAME


socket.h, socket, CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_NXTHDR,
CMSG_SPACE - 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) */


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

void *msg_name /* optional address */
socklen_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 */
socklen_t msg_controllen /* ancillary data buffer len */
int msg_flags /* flags on received message */


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

socklen_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 macros for use as the cmsg_type values when
cmsg_level is SOL_SOCKET.

SCM_RIGHTS
Indicates that the data array contains the access rights
(set of open file descriptors) 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 IPv4 ancillary data formats are listed below by cmsg_level and
cmsg_type, along with the associated payload for each.

IPPROTO_IP, IP_RECVDSTADDR -- SOCK_DGRAM only

ipaddr_t, IP address


IPPROTO_IP, IP_RECVIF

uint_t, ifIndex number


IPPROTO_IP, IP_RECVOPTS -- SOCK_DGRAM only

variable-length IP options, up to 40 bytes


IPPROTO_IP, IP_RECVPKTINFO -- SOCK_DGRAM only

in_pktinfo_t


IPPROTO_IP, IP_RECVSLLA -- SOCK_DGRAM only

struct sockaddr_dl, link layer address


IPPROTO_IP, IP_RECVTTL -- SOCK_DGRAM only

uint8_t, the IP TTL (time to live)


IPPROTO_IP, IP_RECVTOS

uint8_t, the IP TOS (type of service)


SOL_SOCKET, SO_UCRED

ucred_t


The IPv6 ancillary data formats are listed below by cmsg_level and
cmsg_type, along with the associated payload for each.

IPPROTO_IPV6, IPV6_PKTINFO

in_pktinfo_t


IPPROTO_IPV6, IPV6_TCLASS

uint_t


IPPROTO_IPV6, IPV6_PATHMTU

ip6_mtuinfo


IPPROTO_IPV6, IPV6_HOPLIMIT

uint_t


IPPROTO_IPV6, IPV6_HOPOPTS

variable-length IPv6 options


IPPROTO_IPV6, IPV6_DSTOPTS

variable-length IPv6 options


IPPROTO_IPV6, IPV6_RTHDR

variable-length IPv6 options


IPPROTO_IPV6, IPV6_DSTOPTS

variable-length IPv6 options


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, including
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 macros for use as the
level argument of setsockopt() and getsockopt().

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


SOL_ROUTE
Options to be accessed at the routing socket level, not the
protocol level.


The <sys/socket.h> header defines the following macros for use as the
option_name argument of 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).


SO_MAC_EXEMPT
Mandatory Access Control (MAC) exemption for unlabeled
peers. This option is available only if the system is
configured with Trusted Extensions.


SO_ALLZONES
Bypass zone boundaries (privileged).


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.


MSG_NOSIGNAL
Do not generate SIGPIPE signal.


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.


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

void *msg_name /* optional address */
socklen_t msg_namelen /* size of address */
struct iovec *msg_iov /* scatter/gather array */
int msg_iovlen /* # elements in msg_iov */
caddr_t msg_accrights /* access rights sent/received */


The msg_name and msg_namelen parameters specify the destination address
when the socket is unconnected The msg_name can be specified as a NULL
pointer if no names are desired or required. The msg_iov and msg_iovlen
parameters describe the scatter-gather locations, as described in
read(2). The msg_accrights parameter specifies the buffer in which access
rights sent along with the message are received. The msg_accrightslen
specifies the length of the buffer.

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), 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), sockaddr(3SOCKET),
socket(3SOCKET), socket(3XNET), socketpair(3SOCKET), socketpair(3XNET),
ucred_get(3C), attributes(5), standards(5)


September 18, 2020 SOCKET.H(3HEAD)