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(5).


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


SO_PROTOTYPE
for socket in domains AF_INET and AF_INET6, get the
underlying protocol number used in the socket. For
socket in domain AF_ROUTE, get the address family used
in the socket.


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.


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO


close(2), bind(3XNET), endprotoent(3XNET), setsockopt(3XNET),
socket(3XNET), attributes, standards(5)


January 21, 2007 GETSOCKOPT(3XNET)