= nng_setopt(3)
//
// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
//
// This document is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt).  A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//

== NAME

nng_setopt - set socket option

== SYNOPSIS

[source, c]
----
#include <nng/nng.h>

int nng_setopt(nng_socket s, const char *opt, const void *val, size_t valsz);

int nng_setopt_bool(nng_socket s, const char *opt, int bval);

int nng_setopt_int(nng_socket s, const char *opt, int ival);

int nng_setopt_ms(nng_socket s, const char *opt, nng_duration dur);

int nng_setopt_ptr(nng_socket s, const char *opt, void *ptr);

int nng_setopt_size(nng_socket s, const char *opt, size_t z);

int nng_setopt_string(nng_socket s, const char *opt, const char *str);

int nng_setopt_uint64(nng_socket s, const char *opt, uint64_t u64);
----

== DESCRIPTION
(((options, socket)))
The `nng_setopt()` functions are used to configure options for
the socket _s_.
The actual options that may be configured in this way vary, and are
specified by _opt_.
A number of them are documented in <<nng_options.5#,nng_options(5)>>.

Additionally some transport-specific and protocol-specific options are
documented with the transports and protocols themselves.

The details of the type, size, and semantics of the option will depend
on the actual option, and will be documented with the option itself.

TIP: Generally, it will be easier to use one of the typed versions
of this function.

NOTE: No validation that the option is actually of the associated
type is performed, so the caller must take care to use the *correct* typed form.

`nng_setopt()`::
This function is untyped, and can be used to configure any arbitrary data.
The _val_ pointer addresses the data to copy, and _valsz_ is the
size of the objected located at _val_.

`nng_setopt_bool()`::
This function is for options which take a boolean (`bool`).
The _bval_ is passed to the option.

`nng_setopt_int()`::
This function is for options which take an integer (`int`).
The _ival_ is passed to the option.

`nng_setopt_ms()`::
This function is used to configure time durations (such as timeouts) using
type <<nng_duration.5#,`nng_duration`>>.
The duration _dur_ is an integer number of milliseconds.

`nng_setopt_ptr()`::
This function is used to pass a pointer, _ptr_, to structured data.
The data referenced by _ptr_ is generally managed by other functions.
For example, TLS configuration objects created with
(<<nng_tls_config_alloc.3tls#,`nng_tls_config_alloc()`>>)
can be passed this way.
Note that this form is somewhat special in that the object is generally
not copied, but instead the *pointer* to the object is copied.

`nng_setopt_size()`::
This function is used to configure a size, _z_, typically for buffer sizes,
message maximum sizes, and similar options.

`nng_setopt_string()`::
This function is used to pass configure a string, _str_.
Strings passed this way must be legal UTF-8 or ASCII strings, terminated
with a `NUL` (`\0`) byte.
(Other constraints may apply as well, see the documentation for each option
for details.)

`nng_setopt_uint64()`::
This function is used to configure a 64-bit unsigned value, _u64_.
This is typically used for options related to identifiers, network numbers,
and similar.

== RETURN VALUES

This function returns 0 on success, and non-zero otherwise.

== ERRORS

`NNG_ECLOSED`:: Parameter _s_ does not refer to an open socket.
`NNG_EINVAL`:: The value being passed is invalid.
`NNG_ENOTSUP`:: The option _opt_ is not supported.
`NNG_EREADONLY`:: The option _opt_ is read-only.
`NNG_ESTATE`:: The socket is in an inappropriate state for setting this option.

== SEE ALSO

<<nng_getopt.3#,nng_getopt(3)>>,
<<nng_dialer_setopt.3#,nng_dialer_setopt(3)>>,
<<nng_listener_setopt.3#,nng_listener_setopt(3)>>,
<<nng_strerror.3#,nng_strerror(3)>>,
<<nng_options.5#,nng_options(5)>>,
<<nng_socket.5#,nng_socket(5)>>,
<<nng.7#,nng(7)>>
