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

socket.h, socket, CMSG_DATA, CMSG_FIRSTHDR, CMSG_LEN, CMSG_NXTHDR, CMSG_SPACE - Internet Protocol family

#include <sys/socket.h>

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. Each file descriptor requires one int to send or receive.

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 which indicate types of sockets:

SOCK_DGRAM

Datagram socket

SOCK_STREAM

Byte-stream socket

SOCK_RAW

Raw protocol interface

SOCK_RDM

Reliably delivered message

SOCK_SEQPACKET

Sequenced-packet socket

In some cases, the above types are bitwise-inclusive-ORed with zero or more of the following macros which modify the socket's default behavior:

SOCK_CLOEXEC

The socket should have the close-on-exec, FD_CLOEXEC file descriptor flag set on it. The socket will be closed when the process calls any of the exec(2) family of functions.

SOCK_CLOFORK

The socket should have the close-on-fork, FD_CLOFORK file descriptor flag set on it. The socket will be closed in any child process created with the fork(2) family of functions.

SOCK_NDELAY

The socket should have the O_NDELAY flag set. See open(2) for a discussion of the specific non-blocking behavior this implies.

SOCK_NONBLOCK

The socket should have the O_NONBLOCK flag set. See open(2) for a discussion of the specific non-blocking behavior this implies.

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_DOMAIN

Socket family.

SO_TYPE

Socket type.

SO_PROTOCOL, SO_PROTOTYPE

Socket protocol.

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.

MSG_CMSG_CLOEXEC

When receiving a message with the SCM_RIGHTS ancillary data present, all file descriptors should have the close-on-exec, FD_CLOEXEC flag set on them. They will be closed when the process successfully calls any of the exec(2) family of functions. This has no effect when sending SCM_RIGHTS ancillary data.

MSG_CMSG_CLOFORK

When receiving a message with the SCM_RIGHTS ancillary data present, all file descriptors should have the close-on-fork, FD_CLOFORK flag set on them. They will be closed in any child processes created with the fork(2) family of functions. This has no effect when sending SCM_RIGHTS ancillary data.

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.

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Standard

getpeerucred(3C), ucred_get(3C), libsocket(3LIB), accept(3SOCKET), bind(3SOCKET), connect(3SOCKET), getpeername(3SOCKET), getsockname(3SOCKET), getsockopt(3SOCKET), listen(3SOCKET), recv(3SOCKET), recvfrom(3SOCKET), recvmsg(3SOCKET), send(3SOCKET), sendmsg(3SOCKET), sendto(3SOCKET), setsockopt(3SOCKET), shutdown(3SOCKET), sockaddr(3SOCKET), socket(3SOCKET), socketpair(3SOCKET), accept(3XNET), bind(3XNET), connect(3XNET), getpeername(3XNET), getsockname(3XNET), getsockopt(3XNET), listen(3XNET), recv(3XNET), recvfrom(3XNET), recvmsg(3XNET), send(3XNET), sendmsg(3XNET), sendto(3XNET), setsockopt(3XNET), shutdown(3XNET), socket(3XNET), socketpair(3XNET), attributes(7), standards(7)

July 2, 2024 OmniOS