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= nng_socket_get(3)
//
// Copyright 2024 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_socket_get - get socket option
== SYNOPSIS
[source, c]
----
#include <nng/nng.h>
int nng_socket_get_bool(nng_socket s, const char *opt, bool *bvalp);
int nng_socket_get_int(nng_socket s, const char *opt, int *ivalp);
int nng_socket_get_size(nng_socket s, const char *opt, size_t *zp);
int nng_socket_get_uint64(nng_socket s, const char *opt, uint64_t *u64p);
int nng_socket_get_string(nng_socket s, const char *opt, char **strp);
int nng_socket_get_ptr(nng_socket s, const char *opt, void **ptr);
int nng_socket_get_ms(nng_socket s, const char *opt, nng_duration *durp);
int nng_socket_get_addr(nng_socket s, const char *opt, nng_sockaddr *addrp);
----
== DESCRIPTION
(((options, socket)))
The `nng_socket_get` functions are used to retrieve option values for
the xref:nng_socket.5.adoc[socket] _s_.
The actual options that may be retrieved in this way vary.
A number of them are documented in xref:nng_options.5.adoc[nng_options(5)].
Additionally protocol-specific options are documented with the protocols themselves.
IMPORTANT: Access to transport options via this function is deprecated, and may be
removed from a future release. Applications should instead make use of
xref:nng_dialer_get.3.adoc[nng_dialer_get] or
xref:nng_listener_get.3.adoc[nng_listener_get] for specific dialers or listeners.
=== Forms
In all of these forms, the option _opt_ is retrieved from the socket _s_.
The forms vary based on the type of the option they take.
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.
`nng_socket_get_bool()`::
This function is for options which take a Boolean (`bool`).
The value will be stored at _bvalp_.
`nng_socket_get_int()`::
This function is for options which take an integer (`int`).
The value will be stored at _ivalp_.
`nng_socket_get_ms()`::
This function is used to retrieve time xref:nng_duration.5.adoc[durations]
(such as timeouts), stored in _durp_ as a number of milliseconds.
(The special value ((`NNG_DURATION_INFINITE`)) means an infinite amount of time, and
the special value ((`NNG_DURATION_DEFAULT`)) means a context-specific default.)
`nng_socket_get_ptr()`::
This function is used to retrieve a pointer, _ptr_, to structured data.
The data referenced by _ptr_ is generally managed using other functions.
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_socket_get_size()`::
This function is used to retrieve a size into the pointer _zp_,
typically for buffer sizes, message maximum sizes, and similar options.
`nng_socket_get_string()`::
This function is used to retrieve a string into _strp_.
This string is created from the source using xref:nng_strdup.3.adoc[`nng_strdup()`]
and consequently must be freed by the caller using
xref:nng_strfree.3.adoc[`nng_strfree()`] when it is no longer needed.
`nng_socket_get_uint64()`::
This function is used to retrieve a 64-bit unsigned value into the value
referenced by _u64p_.
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_EBADTYPE`:: Incorrect type for option.
`NNG_ECLOSED`:: Parameter _s_ does not refer to an open socket.
`NNG_EINVAL`:: Size of destination _val_ too small for object.
`NNG_ENOMEM`:: Insufficient memory exists.
`NNG_ENOTSUP`:: The option _opt_ is not supported.
`NNG_EWRITEONLY`:: The option _opt_ is write-only.
== SEE ALSO
[.text-left]
xref:nng_dialer_get.3.adoc[nng_dialer_get(3)],
xref:nng_listener_get.3.adoc[nng_listener_get(3)],
xref:nng_pipe_get.3.adoc[nng_pipe_get(3)],
xref:nng_socket_set.3.adoc[nng_socket_set(3)],
xref:nng_strdup.3.adoc[nng_strdup(3)],
xref:nng_strerror.3.adoc[nng_strerror(3)],
xref:nng_strfree.3.adoc[nng_strfree(3)],
xref:nng_duration.5.adoc[nng_duration(5)],
xref:nng_options.5.adoc[nng_options(5)],
xref:nng_socket.5.adoc[nng_socket(5)],
xref:nng.7.adoc[nng(7)]
|
