= 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.

=== Forms

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.

==== `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

These functions return 0 on success, and non-zero otherwise.

== ERRORS

[horizontal]
`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

[.text-left]
<<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)>>
