- NAME
- SYNOPSIS
- DESCRIPTION
- NOTES
- RESTRICTIONS
- RETURN VALUES
- SEE ALSO
- HISTORY

# NAME

OPENSSL_config, OPENSSL_no_config - simple OpenSSL configuration functions

# SYNOPSIS

     #include <openssl/conf.h>

     void OPENSSL_config(const char *config_name);
     void OPENSSL_no_config(void);

# DESCRIPTION

`OPENSSL_config()` configures OpenSSL using the standard openssl.cnf configuration file name using config_name. If config_name is NULL then the default name openssl_conf will be used. Any errors are ignored. Further calls to `OPENSSL_config()` will have no effect. The configuration file format is documented in the conf manual page.

`OPENSSL_no_config()` disables configuration. If called before `OPENSSL_config()` no configuration takes place.

# NOTES

It is strongly recommended that all new applications call `OPENSSL_config()` or the more sophisticated functions such as `CONF_modules_load()` during initialization (that is before starting any threads). By doing this an application does not need to keep track of all configuration options and some new functionality can be supported automatically.

It is also possible to automatically call `OPENSSL_config()` when an application calls `OPENSSL_add_all_algorithms()` by compiling an application with the preprocessor symbol OPENSSL_LOAD_CONF #define'd. In this way configuration can be added without source changes.

The environment variable OPENSSL_CONF can be set to specify the location of the configuration file.

    Currently ASN1 OBJECTs and ENGINE configuration can be performed future
    versions of OpenSSL will add new configuration options.

There are several reasons why calling the OpenSSL configuration routines is advisable. For example new ENGINE functionality was added to OpenSSL 0.9.7. In OpenSSL 0.9.7 control functions can be supported by ENGINEs, this can be used (among other things) to load dynamic ENGINEs from shared libraries (DSOs). However very few applications currently support the control interface and so very few can load and use dynamic ENGINEs. Equally in future more sophisticated ENGINEs will require certain control operations to customize them. If an application calls `OPENSSL_config()` it doesn't need to know or care about ENGINE control operations because they can be performed by editing a configuration file.

Applications should free up configuration at application closedown by calling CONF_modules_free().

# RESTRICTIONS

The `OPENSSL_config()` function is designed to be a very simple ``call it and forget it'' function. As a result its behaviour is somewhat limited. It ignores all errors silently and it can only load from the standard configuration file location for example.

It is however much better than nothing. Applications which need finer control over their configuration functionality should use the configuration functions such as `CONF_load_modules()` directly.

# RETURN VALUES

Neither `OPENSSL_config()` nor `OPENSSL_no_config()` return a value.

# SEE ALSO

conf, CONF_load_modules_file, CONF_modules_free

# HISTORY

`OPENSSL_config()` and `OPENSSL_no_config()` first appeared in OpenSSL 0.9.7