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This documentation is for version 0.5.0 of nng, but the latest released version is v1.8.0. see the documentation for v1.8.0 for the most up-to-date information.
nng_dialer_getopt(3)

SYNOPSIS

#include <nng/nng.h>

int nng_dialer_getopt(nng_dialer d, const char *opt, void *val, size_t *valszp);
int nng_dialer_getopt_int(nng_dialer d, const char *opt, int *ivalp);
int nng_dialer_getopt_ms(nng_dialer d, const char *opt, nng_duration *durp);
int nng_dialer_getopt_ptr(nng_dialer d, const char *opt, void **ptr);
int nng_dialer_setopt_size(nng_dialer d, const char *opt, size_t *zp);
int nng_dialer_getopt_uint64(nng_dialer d, const char *opt, uint64_t *u64p);

DESCRIPTION

The nng_dialer_getopt() functions are used to retrieve option values for the dialer d. The actual options that may be retrieved in this way vary, and are documented in the nng_getopt(3) manual. Additionally some transport-specific options are documented with the transports themselves.

In all of these forms, the option opt is retrieved from the dialer d.

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.

The first form of this function, nng_dialer_getopt(), can be used to retrieve the value of any option. It is untyped. The caller must store a pointer to a buffer to receive the value in val, and the size of the buffer shall be stored at the location referenced by valszp.

When the function returns, the actual size of the data copied (or that would have been copied if sufficient space were present) is stored at the location referened by valszp. If the caller’s buffer is not large enough to hold the entire object, then the copy is truncated. Therefore the caller should validate that the returned size in valszp does not exceed the original buffer size to check for truncation.

It is acceptable to pass NULL for val if the value in valszp is zero. This can be used to determine the size of the buffer needed to receive the object.

Generally, it will be easier to use one of the typed forms instead. Note however that 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.

The second form, nng_dialer_getopt_int(), is for options which take an integer (or boolean). The value will be stored at ivalp. For booleans the value will be eiher 0 (false) or 1 (true).

The third form, nng_dialer_getopt_ms(), is used to retrieve time durations (such as timeouts), stored in durp as a number of milliseconds. (The special value NNG_DUR_INFINITE means an infinite amount of time, and the special value NNG_DUR_DEFAULT means a context-specific default.)

The fourth form, nng_dialer_getopt_ptr(), 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.

The fifth form, nng_dialer_getopt_size(), is used to retrieve a size into the pointer zp, typically for buffer sizes, message maximum sizes, and similar options.

The sixth form, nng_diale_getopt_uint64(), 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

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

ERRORS

NNG_ECLOSED

Parameter d does not refer to an open dialer.

NNG_ENOTSUP

The option opt is not supported.

NNG_EWRITEONLY

The option opt is write-only.

NNG Reference Manual v0.5.0 © 2019 Staysail Systems, Inc, © 2018 Capitar IT Group BV
This document is supplied under the MIT License.
nanomsg™ and nng™ are trademarks of Garrett D'Amore.