146 lines
5.2 KiB
Text
146 lines
5.2 KiB
Text
= nng_dialer_get(3)
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//
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// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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//
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// This document is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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== NAME
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nng_dialer_get - get dialer option
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== SYNOPSIS
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[source, c]
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----
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#include <nng/nng.h>
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int nng_dialer_get(nng_dialer d, const char *opt, void *val, size_t *valszp);
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int nng_dialer_get_bool(nng_dialer d, const char *opt, bool *bvalp);
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int nng_dialer_get_int(nng_dialer d, const char *opt, int *ivalp);
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int nng_dialer_get_ms(nng_dialer d, const char *opt, nng_duration *durp);
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int nng_dialer_get_ptr(nng_dialer d, const char *opt, void **ptr);
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int nng_dialer_get_size(nng_dialer d, const char *opt, size_t *zp);
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int nng_dialer_get_addr(nng_dialer d, const char *opt, nng_sockaddr *sap);
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int nng_dialer_get_string(nng_dialer d, const char *opt, char **strp);
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int nng_dialer_get_uint64(nng_dialer d, const char *opt, uint64_t *u64p);
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----
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== DESCRIPTION
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(((options, dialer)))
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The `nng_dialer_get()` functions are used to retrieve option values for
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the xref:nng_dialer.5.adoc[dialer] _d_.
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The actual options that may be retrieved in this way
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vary, and many are documented in xref:nng_options.5.adoc[nng_options(5)].
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Additionally some transport-specific options are documented with the transports themselves.
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=== Forms
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In all of these forms, the option _opt_ is retrieved from the dialer _d_.
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The forms vary based on the type of the option they take.
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The details of the type, size, and semantics of the option will depend
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on the actual option, and will be documented with the option itself.
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`nng_dialer_get()`::
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This function is untyped and can be used to retrieve the value of any option.
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The caller must store a pointer to a buffer to receive the value in _val_,
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and the size of the buffer shall be stored at the location referenced
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by _valszp_. +
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+
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When the function returns, the actual size of the data copied (or that
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would have been copied if sufficient space were present) is stored at
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the location referenced by _valszp_.
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If the caller's buffer is not large
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enough to hold the entire object, then the copy is truncated.
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Therefore the caller should validate that the returned size in _valszp_ does not
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exceed the original buffer size to check for truncation. +
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+
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It is acceptable to pass `NULL` for _val_ if the value in _valszp_ is zero.
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This can be used to determine the size of the buffer needed to receive
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the object.
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TIP: It may be easier to use one of the typed forms of this function.
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`nng_dialer_get_bool()`::
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This function is for options which take a Boolean (`bool`).
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The value will be stored at _bvalp_.
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`nng_dialer_get_int()`::
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This function is for options which take an integer (`int`).
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The value will be stored at _ivalp_.
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`nng_dialer_get_ms()`::
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This function is used to retrieve time xref:nng_duration.5.adoc[durations]
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(such as timeouts), stored in _durp_ as a number of milliseconds.
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(The special value ((`NNG_DURATION_INFINITE`)) means an infinite amount of time, and
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the special value ((`NNG_DURATION_DEFAULT`)) means a context-specific default.)
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`nng_dialer_get_ptr()`::
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This function is used to retrieve a pointer, _ptr_, to structured data.
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The data referenced by _ptr_ is generally managed using other functions.
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Note that this form is somewhat special in that the object is generally
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not copied, but instead the *pointer* to the object is copied.
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`nng_dialer_get_size()`::
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This function is used to retrieve a size into the pointer _zp_,
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typically for buffer sizes, message maximum sizes, and similar options.
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`nng_dialer_get_addr()`::
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This function is used to retrieve an xref:nng_sockaddr.5.adoc[`nng_sockaddr`]
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into the value referenced by _sap_.
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`nng_dialer_get_string()`::
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This function is used to retrieve a string into _strp_.
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This string is created from the source using xref:nng_strdup.3.adoc[`nng_strdup()`]
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and consequently must be freed by the caller using
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xref:nng_strfree.3.adoc[`nng_strfree()`] when it is no longer needed.
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`nng_dialer_get_uint64()`::
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This function is used to retrieve a 64-bit unsigned value into the value
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referenced by _u64p_.
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This is typically used for options related to identifiers, network
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numbers, and similar.
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== RETURN VALUES
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These functions returns 0 on success, and non-zero otherwise.
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== ERRORS
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[horizontal]
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`NNG_EBADTYPE`:: Incorrect type for option.
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`NNG_ECLOSED`:: Parameter _d_ does not refer to an open dialer.
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`NNG_EINVAL`:: Size of destination _val_ too small for object.
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`NNG_ENOMEM`:: Insufficient memory exists.
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`NNG_ENOTSUP`:: The option _opt_ is not supported.
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`NNG_EWRITEONLY`:: The option _opt_ is write-only.
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== SEE ALSO
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[.text-left]
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xref:nng_dialer_create.3.adoc[nng_dialer_create(3)]
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xref:nng_dialer_set.3.adoc[nng_dialer_set(3)]
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xref:nng_strdup.3.adoc[nng_strdup(3)],
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xref:nng_strerror.3.adoc[nng_strerror(3)],
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xref:nng_strfree.3.adoc[nng_strfree(3)],
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xref:nng_dialer.5.adoc[nng_dialer(5)],
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xref:nng_duration.5.adoc[nng_duration(5)],
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xref:nng_options.5.adoc[nng_options(5)],
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xref:nng_sockaddr.5.adoc[nng_sockaddr(5)],
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xref:nng.7.adoc[nng(7)]
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