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.TH GETSOCKOPT 3XNET "July 2, 2024"
.SH NAME
getsockopt \- get the socket options
.SH SYNOPSIS
\fBcc\fR [ \fIflag\fR... ] \fIfile\fR... \fB-lxnet\fR [ \fIlibrary\fR... ]
#include <sys/socket.h>

\fBint\fR \fBgetsockopt\fR(\fBint\fR \fIsocket\fR, \fBint\fR \fIlevel\fR, \fBint\fR \fIoption_name\fR,
     \fBvoid *restrict\fR \fIoption_value\fR, \fBsocklen_t *restrict\fR \fIoption_len\fR);
.fi

.SH DESCRIPTION
The \fBgetsockopt()\fR function retrieves the value for the option specified by
the \fIoption_name\fR argument for the socket specified by the \fIsocket\fR
argument. If the size of the option value is greater than \fIoption_len\fR, the
value stored in the object pointed to by the \fIoption_value\fR argument will
be silently truncated. Otherwise, the object pointed to by the \fIoption_len\fR
argument will be modified to indicate the actual length of the value.
.sp
.LP
The \fIlevel\fR argument specifies the protocol level at which the option
resides.  To retrieve options at the socket level, specify the \fIlevel\fR
argument as \fBSOL_SOCKET\fR. 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 \fBTCP\fR
(Transport Control Protocol), set \fIlevel\fR to the protocol number of
\fBTCP\fR, as defined in the <\fBnetinet/in.h\fR> header, or as determined by
using \fBgetprotobyname\fR(3XNET) function.
.sp
.LP
The socket in use might require the process to have appropriate privileges to
use the \fBgetsockopt()\fR function.
.sp
.LP
The \fIoption_name\fR argument specifies a single option to be retrieved.  It
can be one of the following values defined in \fB<sys/socket.h>\fR:
.sp
.ne 2
.na
\fB\fBSO_DEBUG\fR\fR
.ad
.RS 17n
Reports whether debugging information is being recorded. This option stores an
\fBint\fR value. This is a boolean option.
.RE

.sp
.ne 2
.na
\fB\fBSO_ACCEPTCONN\fR\fR
.ad
.RS 17n
Reports whether socket listening is enabled. This option stores an \fBint\fR
value.
.RE

.sp
.ne 2
.na
\fB\fBSO_BROADCAST\fR\fR
.ad
.RS 17n
Reports whether transmission of broadcast messages is supported, if this is
supported by the protocol. This option stores an \fBint\fR value. This is a
boolean option.
.RE

.sp
.ne 2
.na
\fB\fBSO_REUSEADDR\fR\fR
.ad
.RS 17n
Reports whether the rules used in validating addresses supplied to
\fBbind\fR(3XNET) should allow reuse of local addresses, if this is supported
by the protocol. This option stores an \fBint\fR value. This is a boolean
option.
.RE

.sp
.ne 2
.na
\fB\fBSO_KEEPALIVE\fR\fR
.ad
.RS 17n
Reports whether connections are kept active with periodic transmission of
messages, if this is supported by the protocol.
.sp
If the connected socket fails to respond to these messages, the connection is
broken and threads writing to that socket are notified with a \fBSIGPIPE\fR
signal. This option stores an \fBint\fR value.
.sp
This is a boolean option.
.RE

.sp
.ne 2
.na
\fB\fBSO_LINGER\fR\fR
.ad
.RS 17n
Reports whether the socket lingers on \fBclose\fR(2) if data is present. If
\fBSO_LINGER\fR is set, the system blocks the process during \fBclose\fR(2)
until it can transmit the data or until the end of the interval indicated by
the \fBl_linger\fR member, whichever comes first. If \fBSO_LINGER\fR is not
specified, and \fBclose\fR(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 \fBlinger\fR structure.
.RE

.sp
.ne 2
.na
\fB\fBSO_OOBINLINE\fR\fR
.ad
.RS 17n
Reports whether the socket leaves received out-of-band data (data marked
urgent) in line. This option stores an \fBint\fR value. This is a boolean
option.
.RE

.sp
.ne 2
.na
\fB\fBSO_SNDBUF\fR\fR
.ad
.RS 17n
Reports send buffer size information. This option stores an \fBint\fR value.
.RE

.sp
.ne 2
.na
\fB\fBSO_RCVBUF\fR\fR
.ad
.RS 17n
Reports receive buffer size information. This option stores an \fBint\fR value.
.RE

.sp
.ne 2
.na
\fB\fBSO_ERROR\fR\fR
.ad
.RS 17n
Reports information about error status and clears it. This option stores an
\fBint\fR value.
.RE

.sp
.ne 2
.na
\fB\fBSO_TYPE\fR\fR
.ad
.RS 17n
Reports the socket type. This option stores an \fBint\fR value.
.RE

.sp
.ne 2
.na
\fB\fBSO_DONTROUTE\fR\fR
.ad
.RS 17n
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 \fBint\fR value. This is a boolean option.
.RE

.sp
.ne 2
.na
\fB\fBSO_MAC_EXEMPT\fR\fR
.ad
.RS 17n
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. \fB\fR\fBSO_MAC_EXEMPT\fR is a boolean option that is
available only when the system is configured with Trusted Extensions.
.RE

.sp
.ne 2
.na
\fB\fBSO_ALLZONES\fR\fR
.ad
.RS 17n
Bypasses zone boundaries (privileged). This option stores an \fBint\fR value.
This is a boolean option.
.sp
The \fBSO_ALLZONES\fR 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, \fBSO_ALLZONES\fR 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 \fBSO_ALLZONES\fR 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 \fBsys_net_config\fR
privilege. See \fBzones\fR(7).
.RE

.sp
.ne 2
.na
\fB\fBSO_DOMAIN\fR\fR
.ad
.RS 17n
get the domain used in the socket (get only)
.RE

.sp
.ne 2
.na
\fB\fBSO_PROTOTYPE\fR\fR,
.B SO_PROTOCOL
.ad
.RS 17n
Get the protocol used in the socket. This may not be the protocol passed in
during a call to \fBsocket\fR(3SOCKET). For example, when protocol 0 is used
with sockets in the domain, \fBPF_INET\fR and \fBPF_INET6\fR, this will return
the underlying protocol that is in use, such as \fBIPPROTO_TCP\fR.
\fBSO_PROTOCOL\fR is the standard POSIX name for this option. \fBSO_PROTOTYPE\fR
is the traditional operating system name for this option. Most sockets do not
support setting this option.
.RE

.sp
.LP
For boolean options, a zero value indicates that the option is disabled and a
non-zero value indicates that the option is enabled.
.sp
.LP
Options at other protocol levels vary in format and name.
.sp
.LP
The socket in use may require the process to have appropriate privileges to use
the \fBgetsockopt()\fR function.
.SH RETURN VALUES
Upon successful completion, \fBgetsockopt()\fR returns \fB0\fR. Otherwise,
\fB\(mi1\fR is returned and \fBerrno\fR is set to indicate the error.
.SH ERRORS
The \fBgetsockopt()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEBADF\fR\fR
.ad
.RS 15n
The \fIsocket\fR argument is not a valid file descriptor.
.RE

.sp
.ne 2
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 15n
The \fIoption_value\fR or \fIoption_len\fR parameter can not be accessed or
written.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 15n
The specified option is invalid at the specified socket level.
.RE

.sp
.ne 2
.na
\fB\fBENOPROTOOPT\fR\fR
.ad
.RS 15n
The option is not supported by the protocol.
.RE

.sp
.ne 2
.na
\fB\fBENOTSOCK\fR\fR
.ad
.RS 15n
The \fIsocket\fR argument does not refer to a socket.
.RE

.sp
.LP
The \fBgetsockopt()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBEACCES\fR\fR
.ad
.RS 11n
The calling process does not have the appropriate privileges.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 11n
The socket has been shut down.
.RE

.sp
.ne 2
.na
\fB\fBENOBUFS\fR\fR
.ad
.RS 11n
Insufficient resources are available in the system to complete the call.
.RE

.sp
.ne 2
.na
\fB\fBENOSR\fR\fR
.ad
.RS 11n
There were insufficient STREAMS resources available for the operation to
complete.
.RE

.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
\fBclose\fR(2), \fBbind\fR(3XNET), \fBendprotoent\fR(3XNET),
\fBsetsockopt\fR(3XNET), \fBsocket\fR(3XNET), \fBattributes\fR,
.BR standards (7)