nn_getsockopt(3compat)

SYNOPSIS

#include <nanomsg/nn.h>
+
+int nn_getsockopt(int sock, int level, int option, void *val, size_t *szp);

DESCRIPTION

The nn_getsockopt() function gets a socket option on socket sock. +The option retrieved is determined by the level and option.

+ + + + + +

+ +	+This function is provided for API +compatibility with legacy libnanomsg. +Consider using the relevant modern API instead. +

The value pointed to by szp must be initialized to the size of the buffer +pointed to by val. +No more than this many bytes of the option will be copied into the destination +buffer on success. +On success, the value pointed to by szp will be updated with the actual +size of the option.

+ + + + + +

+ +	+To determine the size to receive an option, first call this function +with val set to `NULL` and the value addressed by szp initialized to zero. +

The level determines whether the option is a generic socket option, +or is transport-specific. +The values possible for level are as follows:

+ + + + + + + + + + + + + + + + + +

+`NN_SOL_SOCKET` +	+ Generic socket option +
+`NN_IPC` +	+ Transport specific option for IPC. +
+`NN_TCP` +	+ Transport specific option for TCP. +
+`NN_WS` +	+ Transport specific option for WebSocket. +

The following generic socket options are possible (all are of type int and +thus size 4, unless otherwise indicated.)

NN_SNDBUF: +
Send buffer size in bytes.
+

+ + + + + +

+ +

+In nng buffers are sized as a count of messages rather than +bytes; accordingly this value is the nng queue depth multiplied by 1024 +(representing an estimate that the average message size is 1kB). +Applications that have unusual message sizes may wish to adjust the value +used here accordingly. +

NN_RCVBUF: +
Receive buffer size in bytes.
+

+ + + + + +

+ +	+The same caveats for `NN_SNDBUF` apply here as well. +

NN_SNDTIMEO: +
Send time-out in milliseconds. +Send operations will fail with ETIMEDOUT if no message can be received +after this many milliseconds have transpired since the operation was started. +A value of -1 means that no timeout is applied.
+
NN_RCVTIMEO: +
Receive time-out in milliseconds. +Receive operations will fail with ETIMEDOUT if no message can be received +after this many milliseconds have transpired since the operation was started. +A value of -1 means that no timeout is applied.
+
NN_RCVMAXSIZE: +
Maximum receive size in bytes. +The socket will discard messages larger than this on receive. +The default, 1MB, is intended to prevent denial-of-service attacks. +The value -1 removes any limit.
+
NN_RECONNECT_IVL: +
Reconnect interval in milliseconds. +After an outgoing connection is closed or fails, the socket will +automatically attempt to reconnect after this many milliseconds. +This is the starting value for the time, and is used in the first +reconnection attempt after a successful connection is made. +The default is 100.
+
NN_RECONNECT_IVL_MAX: +
Maximum reconnect interval in milliseconds. +Subsequent reconnection attempts after a failed attempt are made at +exponentially increasing intervals (back-off), but the interval is +capped by this value. +If this value is smaller than NN_RECONNECT_IVL, then no exponential +back-off is performed, and each reconnect interval will be determined +solely by NN_RECONNECT_IVL. +The default is zero.
+
NN_LINGER: +
This option is always zero and exists only for compatibility.
+

+ + + + + +

+ + +This option was unreliable in early releases of libnanomsg, and +is unsupported in nng and recent libnanomsg releases. +Applications needing assurance of message delivery should either include an +explicit notification (automatic with the NN_REQ protocol) or allow +sufficient time for the socket to drain before closing the socket or exiting. +

NN_SNDPRIO: +
This option is not implemented at this time.
+
NN_RCVPRIO: +
This option is not implemented at this time.
+
NN_IPV4ONLY: +
This option is not implemented at this time.
+
NN_SOCKET_NAME: +
This option is a string, and represents the socket name. +It can be changed to help with identifying different sockets with +their different application-specific purposes.
+
NN_MAXTTL: +
Maximum “hops” through proxies and devices a message may go through. +This value, if positive, provides some protection against forwarding loops in +device chains.
+

+ + + + + +

+ +	+Not all protocols offer this protection, so care should still be used +in configuring device forwarding. +

NN_DOMAIN: +
This option of type int represents either the value AF_SP or AF_SP_RAW, +corresponding to the value that the socket was created with.
+
NN_PROTOCOL: +
This option option of type int contains the numeric protocol number +that the socket is used with.
+
NN_RCVFD: +
This option returns a file descriptor suitable for use in with poll() or +select() (or other system-specific polling functions). +This descriptor will be readable when a message is available for receiving +at the socket. +This option is of type int on all systems except Windows, where it is of +type SOCKET.
+

+ + + + + +

+ +	+The file descriptor should not be read or written by the application, +and is not the same as any underlying descriptor used for network sockets. +

NN_SNDFD: +
This option returns a file descriptor suitable for use in with poll() or +select() (or other system-specific polling functions). +This descriptor will be readable when the socket is able to accept a message +for sending. +This option is of type int on all systems except Windows, where it is of +type SOCKET.
+

+ + + + + +

+ +	+The file descriptor should not be read or written by the application, +and is not the same as any underlying descriptor used for network sockets. +Furthermore, the file descriptor should only be polled for readability. +

The following option is available for NN_REQ sockets +using the NN_REQ level:

NN_REQ_RESEND_IVL: +
Request retry interval in milliseconds. +If an NN_REQ socket does not receive a reply to a request within this +period of time, the socket will automatically resend the request. +The default value is 60000 (one minute).
+

The following option is available for NN_SURVEYOR sockets +using the NN_SURVEYOR level:

NN_SURVEYOR_DEADLINE: +
Survey deadline in milliseconds for NN_SURVEYOR sockets. +After sending a survey message, the socket will only accept responses +from respondents for this long. +Any responses arriving after this expires are silently discarded.
+

In addition, the following transport specific options are offered:

NN_IPC_SEC_ATTR: +
This NN_IPC option is not supported at this time.
+
NN_IPC_OUTBUFSZ: +
This NN_IPC option is not supported at this time.
+
NN_IPC_INBUFSZE: +
This NN_IPC option is not supported at this time.
+
NN_TCP_NODELAY: +
This NN_TCP option is not supported at this time.
+
NN_WS_MSG_TYPE: +
This NN_WS option is not supported, as nng only supports binary messages +in this implementation.
+

RETURN VALUES

This function returns zero on success, and -1 on failure.

ERRORS

+ + + + + + + + + + + + + + + + + + + + + + + + + +

+`EBADF` +	+ The socket sock is not an open socket. +
+`ENOMEM` +	+ Insufficient memory is available. +
+`ENOPROTOOPT` +	+ The level and/or option is invalid. +
+`EINVAL` +	+ The option, or the value passed, is invalid. +
+`ETERM` +	+ The library is shutting down. +
+`EACCES` +	+ The option cannot be changed. +

nn_getsockopt(3compat) Manual Page

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUES

ERRORS

SEE ALSO