# nng_socket_set(3) Manual Page

## NAME

nng_socket_set - set socket option

## SYNOPSIS

    #include <nng/nng.h>

    int nng_socket_set(nng_socket s, const char *opt, const void *val, size_t valsz);

    int nng_socket_set_bool(nng_socket s, const char *opt, bool bval);

    int nng_socket_set_int(nng_socket s, const char *opt, int ival);

    int nng_socket_set_ms(nng_socket s, const char *opt, nng_duration dur);

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

    int nng_socket_set_size(nng_socket s, const char *opt, size_t z);

    int nng_socket_set_string(nng_socket s, const char *opt, const char *str);

    int nng_socket_set_uint64(nng_socket s, const char *opt, uint64_t u64);

## DESCRIPTION

The `nng_socket_set()` 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).

Protocol-specific options are documented with the protocol in question.

| Access to transport options via this function is deprecated, and may be removed from a future release. Applications should instead make use of nng_dialer_get or nng_listener_get for specific dialers or listeners.

### Forms

The details of the type, size, and semantics of the option will depend on the actual option, and is documented with the option itself.

`nng_socket_set()`

  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.

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

`nng_socket_set_bool()`

  This function is for options which take a Boolean (`bool`). The bval is passed to the option.

`nng_socket_set_int()`

  This function is for options which take an integer (`int`). The ival is passed to the option.

`nng_socket_set_ms()`

  This function is used to configure time durations (such as timeouts) using type `nng_duration`. The duration dur is an integer number of milliseconds.

`nng_socket_set_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()`) can be passed this way.

| This form is somewhat special in that the object is generally not copied, but instead the pointer to the object is copied.

`nng_socket_set_size()`

  This function is used to configure a size, z, typically for buffer sizes, message maximum sizes, and similar options.

`nng_socket_set_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_socket_set_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

`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

nng_socket_get(3), nng_dialer_set(3), nng_listener_set(3), nng_strerror(3), nng_options(5), nng_socket(5), nng(7)