---
name: "nng_tls_config_alloc"
section: "3tls"
platform: "linux"
package: "libnng-dev"
version: "1.10.1-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nng_tls_config_alloc"
---

# nng\_tls\_config\_alloc(3tls)

allocate TLS configuration object

## NAME

nng\_tls\_config\_alloc - allocate TLS configuration object

## SYNOPSIS

```
#include <nng/nng.h>
#include <nng/supplemental/tls/tls.h>
typedef enum nng_tls_mode {
    NNG_TLS_MODE_CLIENT,
    NNG_TLS_MODE_SERVER
} nng_tls_mode;
int nng_tls_config_alloc(nng_tls_config **cfgp, nng_tls_mode mode);
```

## DESCRIPTION

The `nng_tls_config_alloc()` function creates a newly initialized *Transport Layer Security* \<https://tools.ietf.org/html/rfc5246\>) configuration object, and stores a pointer to it in the value pointed to by *cfgp*.

This object is initialized for use when acting as either a client (`NNG_TLS_MODE_CLIENT`) or as a server (`NNG_TLS_MODE_SERVER`), depending on the value of *mode*.

A TLS object can be further modified by functions that set the security keys used, peer certificates, protocol policies, and so forth.

A single TLS configuration object can be used with multiple TLS streams or services. The underlying system uses reference counting to ensure that object is not inadvertently freed while in use.

A configuration object created with `nng_tls_config_alloc()` starts with a reference count of one. The reference count may be incremented using `nng_tls_config_hold()` and may be decremented with `nng_tls_config_free()`.

Also note that a TLS configuration object becomes read-only after it is first used with a service. After this points, attempts to apply further changes to the configuration will result in `NNG_EBUSY`.

## RETURN VALUES

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

## ERRORS

`NNG_ENOMEM`

Insufficient memory is available.

`NNG_EINVAL`

An invalid *mode* was specified.

## SEE ALSO

[nng\_strerror(3)](/nng_strerror/3.md), [nng\_tls\_config\_auth\_mode(3tls)](/nng_tls_config_auth_mode/3tls.md), [nng\_tls\_config\_ca\_chain(3tls)](/nng_tls_config_ca_chain/3tls.md), [nng\_tls\_config\_own\_cert(3tls)](/nng_tls_config_own_cert/3tls.md), [nng\_tls\_config\_free(3tls)](/nng_tls_config_free/3tls.md), [nng\_tls\_config\_hold(3tls)](/nng_tls_config_hold/3tls.md), [nng\_tls\_config\_server\_name(3tls)](/nng_tls_config_server_name/3tls.md), [nng\_tls\_config(5)](/nng_tls_config/5.md), [nng(7)](/nng/7.md)