MirBSD manpage: OPENSSL_config(3), OPENSSL_no_config(3)

OPENSSL_CONFIG(3)            OpenSSL            OPENSSL_CONFIG(3)


     OPENSSL_config, OPENSSL_no_config - simple OpenSSL confi-
     guration functions


      #include <openssl/conf.h>

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


     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(5) manual page.

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


     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 per-
     formed future versions of OpenSSL will add new configuration

     There are several reasons why calling the OpenSSL configura-
     tion routines is advisable. For example new ENGINE func-
     tionality was added to OpenSSL 0.9.7. In OpenSSL 0.9.7 con-
     trol 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

MirBSD #10-current         2014-06-05                           1

OPENSSL_CONFIG(3)            OpenSSL            OPENSSL_CONFIG(3)

     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().


     The OPENSSL_config() function is designed to be a very sim-
     ple "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 configura-
     tion 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.


     Neither OPENSSL_config() nor OPENSSL_no_config() return a


     conf(5), CONF_load_modules_file(3), CONF_modules_free(3)


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

MirBSD #10-current         2014-06-05                           2

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