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


setsockopt - set the socket options


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

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


The setsockopt() function sets the option specified by the option_name
argument, at the protocol level specified by the level argument, to the
value pointed to by the option_value argument for the socket associated
with the file descriptor specified by the socket argument.

The level argument specifies the protocol level at which the option
resides. To set options at the socket level, specify the level argument
as SOL_SOCKET. To set 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

The option_name argument specifies a single option to set. The
option_name argument and any specified options are passed uninterpreted
to the appropriate protocol module for interpretations. The
<sys/socket.h> header defines the socket level options. The options are
as follow

Turns on recording of debugging information. This
option enables or disables debugging in the underlying
protocol modules. This option takes an int value. This
is a boolean option.

Permits sending of broadcast messages, if this is
supported by the protocol. This option takes an int
value. This is a boolean option.

Specifies that 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 takes an int value. This is a boolean option.

Keeps connections active by enabling the periodic
transmission of messages, if this is supported by the
protocol. This option takes an int value.

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 is a boolean option.

Lingers on a close(2) if data is present. This option
controls the action taken when unsent messages queue on
a socket and close(2) is performed. If SO_LINGER is
set, the system blocks the process during close(2) until
it can transmit the data or until the time expires. 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 takes a
linger structure, as defined in the <sys/socket.h>
header, to specify the state of the option and linger

Leaves received out-of-band data (data marked urgent) in
line. This option takes an int value. This is a boolean

Sets send buffer size. This option takes an int value.

Sets receive buffer size. This option takes an int

Requests that 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 takes an
int value. This is a boolean option.

Sets the mandatory access control on 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.

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).

For boolean options, 0 indicates that the option is disabled and 1
indicates that the option is enabled.

Options at other protocol levels vary in format and name.


The setsockopt() function provides an application program with the means
to control socket behavior. An application program can use setsockopt()
to allocate buffer space, control timeouts, or permit socket data
broadcasts. The <sys/socket.h> header defines the socket-level options
available to setsockopt().

Options may exist at multiple protocol levels. The SO_ options are always
present at the uppermost socket level.


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


The setsockopt() function will fail if:

The socket argument is not a valid file descriptor.

The send and receive timeout values are too big to fit
into the timeout fields in the socket structure.

The option_value parameter can not be accessed or written.

The specified option is invalid at the specified socket
level or the socket has been shut down.

The socket is already connected, and a specified option
can not be set while the socket is connected.

The option is not supported by the protocol.

The socket argument does not refer to a socket.

The setsockopt() function may fail if:

There was insufficient memory available for the operation to

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

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


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

|Interface Stability | Standard |
|MT-Level | MT-Safe |


bind(3XNET), endprotoent(3XNET), getsockopt(3XNET), socket(3XNET),
attributes(7), standards(7)

January 21, 2007 SETSOCKOPT(3XNET)