NAME

       nng_getopt - get socket option

SYNOPSIS

           #include <nng/nng.h>

           int nng_getopt(nng_socket s, const char *opt, void *val, size_t *valszp);

           int nng_getopt_bool(nng_socket s, const char *opt, bool *bvalp);

           int nng_getopt_int(nng_socket s, const char *opt, int *ivalp);

           int nng_getopt_ms(nng_socket s, const char *opt, nng_duration *durp);

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

           int nng_getopt_size(nng_socket s, const char *opt, size_t *zp);

           int nng_getopt_string(nng_socket s, const char *opt, char **strp);

           int nng_getopt_uint64(nng_socket s, const char *opt, uint64_t *u64p);

DESCRIPTION

           Important
           These functions are deprecated. Please see nng_socket_get. They may not be present if
           the library was built with NNG_ELIDE_DEPRECATED.

       The nng_getopt() functions are used to retrieve option values for the socket s. The actual
       options that may be retrieved in this way vary. A number of them are documented in
       nng_options(5).

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

   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_getopt()
           This function is untyped and can be used to retrieve the value of any option. 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 referenced 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 check for truncation by verifying that
           the returned size in valszp does not exceed the original buffer size.

           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.

               Tip
               It may be easier to use one of the typed forms of this function.

       nng_getopt_bool()
           This function is for options which take a Boolean (bool). The value will be stored at
           bvalp.

       nng_getopt_int()
           This function is for options which take an integer (int). The value will be stored at
           ivalp.

       nng_getopt_ms()
           This function is used to retrieve time 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_getopt_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_getopt_size()
           This function is used to retrieve a size into the pointer zp, typically for buffer
           sizes, message maximum sizes, and similar options.

       nng_getopt_string()
           This function is used to retrieve a string into strp. This string is created from the
           source using nng_strdup() and consequently must be freed by the caller using
           nng_strfree() when it is no longer needed.

       nng_getopt_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

       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

       nng_dialer_getopt(3), nng_listener_getopt(3), nng_pipe_getopt(3), nng_setopt(3),
       nng_strdup(3), nng_strerror(3), nng_strfree(3), nng_duration(5), nng_options(5),
       nng_socket(5), nng(7)

                                            2024-10-11                              NNG_GETOPT(3)