Tribblix: manual page: getsockopt.3xnet

GETSOCKOPT(3XNET) X/Open Networking Services Library Functions

NAME

getsockopt - get the socket options

SYNOPSIS

cc [ flag... ] file... -lxnet [ library... ] #include <sys/socket.h>

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

DESCRIPTION

The getsockopt() function retrieves the value for the option
specified by the option_name argument for the socket specified by the
socket argument. If the size of the option value is greater than
option_len, the value stored in the object pointed to by the
option_value argument will be silently truncated. Otherwise, the
object pointed to by the option_len argument will be modified to
indicate the actual length of the value.

The level argument specifies the protocol level at which the option
resides. To retrieve options at the socket level, specify the level
argument as SOL_SOCKET. To retrieve options at other levels, supply
the appropriate protocol number for the protocol controlling the
option. For example, to indicate that an option will be interpreted
by the TCP (Transport Control Protocol), set level to the protocol
number of TCP, as defined in the <netinet/in.h> header, or as
determined by using getprotobyname(3XNET) function.

The socket in use might require the process to have appropriate
privileges to use the getsockopt() function.

The option_name argument specifies a single option to be retrieved.
It can be one of the following values defined in <sys/socket.h>:

SO_DEBUG
Reports whether debugging information is being
recorded. This option stores an int value. This is a
boolean option.

SO_ACCEPTCONN
Reports whether socket listening is enabled. This
option stores an int value.

SO_BROADCAST
Reports whether transmission of broadcast messages
is supported, if this is supported by the protocol.
This option stores an int value. This is a boolean
option.

SO_REUSEADDR
Reports whether the rules used in validating
addresses supplied to bind(3XNET) should allow reuse
of local addresses, if this is supported by the
protocol. This option stores an int value. This is a
boolean option.

SO_KEEPALIVE
Reports whether connections are kept active with
periodic transmission of messages, if this is
supported by the protocol.

If the connected socket fails to respond to these
messages, the connection is broken and threads
writing to that socket are notified with a SIGPIPE
signal. This option stores an int value.

This is a boolean option.

SO_LINGER
Reports whether the socket lingers on close(2) if
data is present. If SO_LINGER is set, the system
blocks the process during close(2) until it can
transmit the data or until the end of the interval
indicated by the l_linger member, whichever comes
first. If SO_LINGER is not specified, and close(2)
is issued, the system handles the call in a way that
allows the process to continue as quickly as
possible. This option stores a linger structure.

SO_OOBINLINE
Reports whether the socket leaves received out-of-
band data (data marked urgent) in line. This option
stores an int value. This is a boolean option.

SO_SNDBUF
Reports send buffer size information. This option
stores an int value.

SO_RCVBUF
Reports receive buffer size information. This option
stores an int value.

SO_ERROR
Reports information about error status and clears
it. This option stores an int value.

SO_TYPE
Reports the socket type. This option stores an int
value.

SO_DONTROUTE
Reports whether outgoing messages bypass the
standard routing facilities. The destination must be
on a directly-connected network, and messages are
directed to the appropriate network interface
according to the destination address. The effect, if
any, of this option depends on what protocol is in
use. This option stores an int value. This is a
boolean option.

SO_MAC_EXEMPT
Gets the mandatory access control status of the
socket. A socket that has this option enabled can
communicate with an unlabeled peer if the socket is
in the global zone or has a label that dominates the
default label of the peer. Otherwise, the socket
must have a label that is equal to the default label
of the unlabeled peer. SO_MAC_EXEMPT is a boolean
option that is available only when the system is
configured with Trusted Extensions.

SO_ALLZONES
Bypasses zone boundaries (privileged). This option
stores an int value. This is a boolean option.

The SO_ALLZONES option can be used to bypass zone
boundaries between shared-IP zones. Normally, the
system prevents a socket from being bound to an
address that is not assigned to the current zone. It
also prevents a socket that is bound to a wildcard
address from receiving traffic for other zones.
However, some daemons which run in the global zone
might need to send and receive traffic using
addresses that belong to other shared-IP zones. If
set before a socket is bound, SO_ALLZONES causes the
socket to ignore zone boundaries between shared-IP
zones and permits the socket to be bound to any
address assigned to the shared-IP zones. If the
socket is bound to a wildcard address, it receives
traffic intended for all shared-IP zones and behaves
as if an equivalent socket were bound in each active
shared-IP zone. Applications that use the
SO_ALLZONES option to initiate connections or send
datagram traffic should specify the source address
for outbound traffic by binding to a specific
address. There is no effect from setting this option
in an exclusive-IP zone. Setting this option
requires the sys_net_config privilege. See zones(7).

SO_DOMAIN
get the domain used in the socket (get only)

SO_PROTOTYPE, SO_PROTOCOL
Get the protocol used in the socket. This may not be
the protocol passed in during a call to
socket(3SOCKET). For example, when protocol 0 is
used with sockets in the domain, PF_INET and
PF_INET6, this will return the underlying protocol
that is in use, such as IPPROTO_TCP. SO_PROTOCOL is
the standard POSIX name for this option.
SO_PROTOTYPE is the traditional operating system
name for this option. Most sockets do not support
setting this option.

For boolean options, a zero value indicates that the option is
disabled and a non-zero value indicates that the option is enabled.

Options at other protocol levels vary in format and name.

The socket in use may require the process to have appropriate
privileges to use the getsockopt() function.

RETURN VALUES

Upon successful completion, getsockopt() returns 0. Otherwise, -1 is
returned and errno is set to indicate the error.

ERRORS

The getsockopt() function will fail if:

EBADF
The socket argument is not a valid file descriptor.

EFAULT
The option_value or option_len parameter can not be
accessed or written.

EINVAL
The specified option is invalid at the specified
socket level.

ENOPROTOOPT
The option is not supported by the protocol.

ENOTSOCK
The socket argument does not refer to a socket.

The getsockopt() function may fail if:

EACCES
The calling process does not have the appropriate
privileges.

EINVAL
The socket has been shut down.

ENOBUFS
Insufficient resources are available in the system to
complete the call.

ENOSR
There were insufficient STREAMS resources available for
the operation to complete.