/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/crypto
Page 1 (printed 10/20/05)
OPENSSL_config(3) 2/Mar/2004 (0.9.7e) OPENSSL_config(3)
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(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_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_CONFIG 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
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OPENSSL_config(3) 2/Mar/2004 (0.9.7e) OPENSSL_config(3)
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(5), CONF_load_modules_file(3), the
CONF_modules_free(3),CONF_modules_free(3) manpage
HISTORY
OPENSSL_config() and OPENSSL_no_config() first appeared in
OpenSSL 0.9.7
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