int getsockopt(

int socket,

int level,

int option_name,

void *option_value,

int *option_len

);

Type

Meaning

SO_ACCEPTCONN

Reports whether socket listening is enabled. This option  stores an int value. This is a Boolean option.

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 allows 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. This option shall store an int value. This is a Boolean option.

SO_LINGER

Reports whether the socket lingers on closesocket if data is present. If SO_LINGER is set, the system blocks the calling thread during closesocket 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 closesocket is issued, the system handles the call in a way that allows the calling thread 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) inline. 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 shall store 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 shall 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_RCVLOWAT

Reports the minimum number of bytes to process for socket input operations. The default value for SO_RCVLOWAT is 1. If SO_RCVLOWAT is set to a larger value, blocking receive calls normally wait until they have received the smaller of the low water mark value or the requested amount. (They may return less than the low water mark if an error occurs, a signal is caught, or the type of data next in the receive queue is different from that returned; for example, out-of-band data.) This option stores an int value.

SO_RCVTIMEO

Reports the timeout value for input operations. This option stores a timeval structure with the number of seconds and microseconds specifying the limit on how long to wait for an input operation to complete. If a receive operation has blocked for this much time without receiving additional data, it returns with a partial count or errno set to [EAGAIN] or [EWOULDBLOCK] if no data was received. The default for this option is zero, which indicates that a receive operation shall not time out.

SO_SNDLOWAT

Reports the minimum number of bytes to process for socket output operations. Non-blocking output operations process no data if flow control does not allow the smaller of the send low water mark value or the entire request to be processed. This option shall store an int value.

SO_SNDTIMEO

Reports the timeout value specifying the amount of time that an output function blocks because flow control prevents data from being sent. If a send operation has blocked for this time, it returns with a partial count or with errno set to [EAGAIN] or [EWOULDBLOCK] if no data was sent. The default for this option is zero, which indicates that a send operation shall not time out. The option stores a timeval structure.