Sockets Library Functions getsockopt(3SOCKET)
NAME
getsockopt, setsockopt - get and set options on sockets
SYNOPSIS
cc [ flag ... ] file ... -lsocket -lnsl [ library ... ]
#include
#include
int getsockopt(int s, int level, int optname, void *optval,
int *optlen); int setsockopt(int s, int level, int optname, const void *optval, int optlen);DESCRIPTION
The getsockopt() and setsockopt() functions manipulate
options associated with a socket. Options may exist at mul-
tiple protocol levels; they are always present at the upper-
most "socket" level. The level argument specifies the protocol level at which the option resides. To manipulate options at the socket level,specify the level argument as SOL_SOCKET. To manipulate
options at the protocol level, supply the appropriate proto-
col number for the protocol controlling the option. For example, to indicate that an option will be interpreted by the TCP, set level to the protocol number of TCP, as defined in theheader, or as determined by using getprotobyname(3SOCKET). Some socket protocol families may also define additional levels, such as SOL_ROUTE. Only
socket-level options are described here.
The parameters optval and optlen are used to access optionvalues for setsockopt(). For getsockopt(), they identify a
buffer in which the value(s) for the requested option(s) areto be returned. For getsockopt(), optlen is a value-result
parameter, initially containing the size of the buffer pointed to by optval, and modified on return to indicate the actual size of the value returned. Use a 0 optval if no option value is to be supplied or returned.The optname and any specified options are passed uninter-
preted to the appropriate protocol module for interpreta-
tion. The include filecontains definitions for the socket-level options described below. Options at
other protocol levels vary in format and name.SunOS 5.11 Last change: 27 Jan 2009 1
Sockets Library Functions getsockopt(3SOCKET)
Most socket-level options take an int for optval. For set-
sockopt(), the optval parameter should be non-zero to enable
a boolean option, or zero if the option is to be disabled.SO_LINGER uses a struct linger parameter that specifies the
desired state of the option and the linger interval. struct linger is defined in. struct linger contains the following members: l_onoff on = 1/off = 0
l_linger linger time, in seconds
The following options are recognized at the socket level.Except as noted, each may be examined with getsockopt() and
set with setsockopt().SO_DEBUG enable/disable recording of debugging
informationSO_REUSEADDR enable/disable local address reuse
SO_KEEPALIVE enable/disable keep connections alive
SO_DONTROUTE enable/disable routing bypass for outgo-
ing messagesSO_LINGER linger on close if data is present
SO_BROADCAST enable/disable permission to transmit
broadcast messagesSO_OOBINLINE enable/disable reception of out-of-band
data in bandSO_SNDBUF set buffer size for output
SO_RCVBUF set buffer size for input
SO_DGRAM_ERRIND application wants delayed error
SunOS 5.11 Last change: 27 Jan 2009 2
Sockets Library Functions getsockopt(3SOCKET)
SO_TIMESTAMP enable/disable reception of timestamp
with datagramsSO_EXCLBIND enable/disable exclusive binding of the
socketSO_TYPE get the type of the socket (get only)
SO_ERROR get and clear error on the socket (get
only)SO_MAC_EXEMPT get or set mandatory access control on
the socket. This option is available only when the system is configured with Trusted Extensions.SO_ALLZONES bypass zone boundaries (privileged).
SO_DOMAIN get the domain used in the socket (get
only)SO_PROTOTYPE for socket in domains PF_INET and
PF_INET6, get the underlying protocol
number used in the socket. For socket indomain PF_ROUTE, get the address family
used in the socket.The SO_DEBUG option enables debugging in the underlying pro-
tocol modules. The SO_REUSEADDR option indicates that the
rules used in validating addresses supplied in a bind(3SOCKET) call should allow reuse of local addresses.The SO_KEEPALIVE option enables the periodic transmission of
messages on a connected socket. If the connected party fails to respond to these messages, the connection is considered broken and threads using the socket are notified using aSIGPIPE signal. The SO_DONTROUTE option indicates that out-
going messages should bypass the standard routing facili-
ties. Instead, messages are directed to the appropriate net-
work interface according to the network portion of the des-
tination address.SunOS 5.11 Last change: 27 Jan 2009 3
Sockets Library Functions getsockopt(3SOCKET)
The SO_LINGER option controls the action taken when unsent
messages are queued on a socket and a close(2) is performed. If the socket promises reliable delivery of data andSO_LINGER is set, the system will block the thread on the
close() attempt until it is able to transmit the data or until it decides it is unable to deliver the information (a timeout period, termed the linger interval, is specified inthe setsockopt() call when SO_LINGER is requested). If
SO_LINGER is disabled and a close() is issued, the system
will process the close() in a manner that allows the thread to continue as quickly as possible.The option SO_BROADCAST requests permission to send broad-
cast datagrams on the socket. With protocols that supportout-of-band data, the SO_OOBINLINE option requests that
out-of-band data be placed in the normal data input queue as
received; it will then be accessible with recv() or read()calls without the MSG_OOB flag.
The SO_SNDBUF and SO_RCVBUF options adjust the normal buffer
sizes allocated for output and input buffers, respectively.The buffer size may be increased for high-volume connections
or may be decreased to limit the possible backlog of incom-
ing data. The maximum buffer size for UDP is determined bythe value of the ndd variable udp_max_buf. The maximum
buffer size for TCP is determined the value of the ndd vari-
able tcp_max_buf. Use the ndd(1M) utility to determine the
current default values. See the Solaris Tunable Parameters Reference Manual for information on setting the values ofudp_max_buf and tcp_max_buf. At present, lowering SO_RCVBUF
on a TCP connection after it has been established has no effect. By default, delayed errors (such as ICMP port unreachable packets) are returned only for connected datagram sockets.The SO_DGRAM_ERRIND option makes it possible to receive
errors for datagram sockets that are not connected. When this option is set, certain delayed errors received after completion of a sendto() or sendmsg() operation will cause a subsequent sendto() or sendmsg() operation using the same destination address (to parameter) to fail with the appropriate error. See send(3SOCKET).If the SO_TIMESTAMP option is enabled on a SO_DGRAM or a
SO_RAW socket, the recvmsg(3XNET) call will return a times-
tamp in the native data format, corresponding to when the datagram was received.SunOS 5.11 Last change: 27 Jan 2009 4
Sockets Library Functions getsockopt(3SOCKET)
The SO_EXCLBIND option is used to enable or disable the
exclusive binding of a socket. It overrides the use of theSO_REUSEADDR option to reuse an address on bind(3SOCKET).
The actual semantics of the SO_EXCLBIND option depend on the
underlying protocol. See tcp(7P) or udp(7P) for more infor-
mation.The SO_TYPE and SO_ERROR options are used only with get-
sockopt(). The SO_TYPE option returns the type of the
socket, for example, SOCK_STREAM. It is useful for servers
that inherit sockets on startup. The SO_ERROR option returns
any pending error on the socket and clears the error status. It may be used to check for asynchronous errors on connected datagram sockets or for other asynchronous errors.The SO_MAC_EXEMPT option is used to toggle socket behavior
with unlabeled peers. A socket that has this option enabledcan communicate with an unlabeled peer if it is in the glo-
bal 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. Calling setsockopt() with this option returns an EACCES error if theprocess lacks the NET_MAC_AWARE privilege or if the socket
is bound. The SO_MAC_EXEMPT option is available only when
the system is configured with Trusted Extensions.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 thatbelong to other shared-IP zones. If set before a socket is
bound, SO_ALLZONES causes the socket to ignore zone boun-
daries 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 trafficintended 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 anexclusive-IP zone. Setting this option requires the
sys_net_config privilege. See zones(5).
RETURN VALUES
SunOS 5.11 Last change: 27 Jan 2009 5
Sockets Library Functions getsockopt(3SOCKET)
If successful, getsockopt() and setsockopt() return 0. Oth-
erwise, the functions return -1 and set errno to indicate
the error.ERRORS
The getsockopt() and setsockopt() calls succeed unless:
EBADF The argument s is not a valid file descrip-
tor. EACCES Permission denied. EADDRINUSE Address already joined forIP_ADD_MEMBERSHIP.
EADDRNOTAVAIL Bad interface address for IP_ADD_MEMBERSHIP
and IP_DROP_MEMBERSHIP.
EHOSTUNREACH Invalid address for IP_MULTICAST_IF.
EINVAL Invalid length for IP_OPTIONS.
Not a multicast address forIP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP.
The specified option is invalid at the specified socket level, or the socket has been shut down.ENOBUFS SO_SNDBUF or SO_RCVBUF exceeds a system
limit.ENOENT Address not joined for IP_DROP_MEMBERSHIP.
ENOMEM There was insufficient memory available for the operation to complete.ENOPROTOOPT The option is unknown at the level indi-
cated. ENOSR There were insufficient STREAMS resources available for the operation to complete.SunOS 5.11 Last change: 27 Jan 2009 6
Sockets Library Functions getsockopt(3SOCKET)
ENOTSOCK The argument s is not a socket. EPERM No permissions.ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| MT-Level | Safe |
|_____________________________|_____________________________|
SEE ALSO
ndd(1M), close(2), ioctl(2), read(2), bind(3SOCKET), getprotobyname(3SOCKET), recv(3SOCKET), recvmsg(3XNET),send(3SOCKET), socket(3SOCKET), socket.h(3HEAD), attri-
butes(5), zones(5), tcp(7P), udp(7P) Solaris Tunable Parameters Reference ManualSunOS 5.11 Last change: 27 Jan 2009 7