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. When manipulating socket options, the level at which the option resides and the name of the option must be specified. To manipulate options at the "socket" level, level is speci- fied as SOL_SOCKET. To manipulate options at any other level, level is the protocol number of the protocol that controls the option. For example, to indicate that an option is to be interpreted by the TCP protocol, level is set to the TCP protocol number. See getprotobyname(3SOCKET). The parameters optval and optlen are used to access option values for setsockopt(). For getsockopt(), they identify a buffer in which the value(s) for the requested option(s) are to 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. optname and any specified options are passed uninterpreted to the appropriate protocol module for interpretation. The include file contains definitions for the socket-level options described below. Options at other pro- tocol levels vary in format and name. 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: SunOS 5.10 Last change: 07 Aug 2006 1 Sockets Library Functions getsockopt(3SOCKET) 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 debug- ging information SO_REUSEADDR enable/disable local address reuse SO_KEEPALIVE enable/disable keep connections alive SO_DONTROUTE enable/disable routing bypass for outgoing messages SO_LINGER linger on close if data is present SO_BROADCAST enable/disable permission to transmit broadcast messages SO_OOBINLINE enable/disable reception of out-of- band data in band SO_SNDBUF set buffer size for output SO_RCVBUF set buffer size for input SunOS 5.10 Last change: 07 Aug 2006 2 Sockets Library Functions getsockopt(3SOCKET) SO_DGRAM_ERRIND application wants delayed error SO_TIMESTAMP enable/disable reception of times- tamp with datagrams SO_EXCLBIND enable/disable exlusive binding of the socket SO_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 avail- able only when the system is config- ured with Trusted Extensions. SO_ALLZONES bypass zone boundaries (privileged). SO_DEBUG enables debugging in the underlying protocol modules. SO_REUSEADDR indicates that the rules used in vali- dating addresses supplied in a bind(3SOCKET) call should allow reuse of local addresses. SO_KEEPALIVE 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 a SIGPIPE signal. SO_DONTROUTE indicates that outgoing messages should bypass the standard routing facilities. Instead, messages are directed to the appropri- ate network interface according to the network portion of the destination address. SO_LINGER 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 and SO_LINGER is set, the system will block the thread on the close() attempt SunOS 5.10 Last change: 07 Aug 2006 3 Sockets Library Functions getsockopt(3SOCKET) 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 in the 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 support out-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. SO_SNDBUF and SO_RCVBUF are options that adjust the normal buffer sizes allocated for output and input buffers, respec- tively. The buffer size may be increased for high-volume connections or may be decreased to limit the possible back- log of incoming data. The maximum buffer size for UDP is determined by the value of the ndd variable udp_max_buf. The maximum buffer size for TCP is determined the value of the ndd variable tcp_max_buf. Use the ndd(1M) utility to deter- mine the current default values. See the Solaris Tunable Parameters Reference Manual for information on setting the values of udp_max_buf and tcp_max_buf. By default, delayed errors (such as ICMP port unreachable packets) are returned only for connected datagram sockets. SO_DGRAM_ERRIND 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. The SO_EXCLBIND option is used to enable or disable the exclusive binding of a socket. It overrides the use of the SO_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 used only with get- sockopt(). SO_TYPE returns the type of the socket, for exam- ple, SOCK_STREAM. It is useful for servers that inherit SunOS 5.10 Last change: 07 Aug 2006 4 Sockets Library Functions getsockopt(3SOCKET) sockets on startup. SO_ERROR 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 enabled can 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 the process 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 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 out- bound 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_ip_config privilege. See zones(5). RETURN VALUES 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 descriptor. ENOMEM There was insufficient memory avail- able for the operation to complete. SunOS 5.10 Last change: 07 Aug 2006 5 Sockets Library Functions getsockopt(3SOCKET) ENOPROTOOPT The option is unknown at the level indicated. ENOSR There were insufficient STREAMS resources available for the opera- tion to complete. ENOTSOCK The argument s is not a socket. ENOBUFS SO_SNDBUF or SO_RCVBUF exceeds a system limit. EINVAL Invalid length for IP_OPTIONS. EHOSTUNREACH Invalid address for IP_MULTICAST_IF. EINVAL Not a multicast address for IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP. EADDRNOTAVAIL Bad interface address for IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP. EADDRINUSE Address already joined for IP_ADD_MEMBERSHIP. ENOENT Address not joined for IP_DROP_MEMBERSHIP. EPERM No permissions. SunOS 5.10 Last change: 07 Aug 2006 6 Sockets Library Functions getsockopt(3SOCKET) EACCES Permission denied. EINVAL The specified option is invalid at the specified socket level, or the socket has been shut down. 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 Manual SunOS 5.10 Last change: 07 Aug 2006 7