OPENSSL_config(3)                   OpenSSL                  OPENSSL_config(3)



NAME
       OPENSSL_config, OPENSSL_no_config - simple OpenSSL configuration func-
       tions

LIBRARY
       libcrypto, -lcrypto

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 con-
       figuration 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(5) 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_con-
       fig() 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 applica-
       tion 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 loca-
       tion 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 rou-
       tines 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 cer-
       tain 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 configu-
       ration functions such as CONF_load_modules() directly.

RETURN VALUES
       Neither OPENSSL_config() nor OPENSSL_no_config() return a value.

SEE ALSO
       conf(5), CONF_load_modules_file(3), CONF_modules_free(3),CONF_mod-
       ules_free(3)

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



0.9.9-dev                         2005-11-24                 OPENSSL_config(3)
