OPENSSL_config.pod revision 267258 
1=pod
2
3=head1 NAME
4
5OPENSSL_config, OPENSSL_no_config - simple OpenSSL configuration functions
6
7=head1 SYNOPSIS
8
9 #include <openssl/conf.h>
10
11 void OPENSSL_config(const char *config_name);
12 void OPENSSL_no_config(void);
13
14=head1 DESCRIPTION
15
16OPENSSL_config() configures OpenSSL using the standard B<openssl.cnf>
17configuration file name using B<config_name>. If B<config_name> is NULL then
18the default name B<openssl_conf> will be used. Any errors are ignored. Further
19calls to OPENSSL_config() will have no effect. The configuration file format
20is documented in the L<conf(5)|conf(5)> manual page.
21
22OPENSSL_no_config() disables configuration. If called before OPENSSL_config()
23no configuration takes place.
24
25=head1 NOTES
26
27It is B<strongly> recommended that B<all> new applications call OPENSSL_config()
28or the more sophisticated functions such as CONF_modules_load() during
29initialization (that is before starting any threads). By doing this
30an application does not need to keep track of all configuration options
31and some new functionality can be supported automatically.
32
33It is also possible to automatically call OPENSSL_config() when an application
34calls OPENSSL_add_all_algorithms() by compiling an application with the
35preprocessor symbol B<OPENSSL_LOAD_CONF> #define'd. In this way configuration
36can be added without source changes.
37
38The environment variable B<OPENSSL_CONF> can be set to specify the location
39of the configuration file.
40 
41Currently ASN1 OBJECTs and ENGINE configuration can be performed future
42versions of OpenSSL will add new configuration options.
43
44There are several reasons why calling the OpenSSL configuration routines is
45advisable. For example new ENGINE functionality was added to OpenSSL 0.9.7.
46In OpenSSL 0.9.7 control functions can be supported by ENGINEs, this can be
47used (among other things) to load dynamic ENGINEs from shared libraries (DSOs).
48However very few applications currently support the control interface and so
49very few can load and use dynamic ENGINEs. Equally in future more sophisticated
50ENGINEs will require certain control operations to customize them. If an
51application calls OPENSSL_config() it doesn't need to know or care about
52ENGINE control operations because they can be performed by editing a
53configuration file.
54
55Applications should free up configuration at application closedown by calling
56CONF_modules_free().
57
58=head1 RESTRICTIONS
59
60The OPENSSL_config() function is designed to be a very simple "call it and
61forget it" function. As a result its behaviour is somewhat limited. It ignores
62all errors silently and it can only load from the standard configuration file
63location for example.
64
65It is however B<much> better than nothing. Applications which need finer
66control over their configuration functionality should use the configuration
67functions such as CONF_load_modules() directly.
68
69=head1 RETURN VALUES
70
71Neither OPENSSL_config() nor OPENSSL_no_config() return a value.
72
73=head1 SEE ALSO
74
75L<conf(5)|conf(5)>, L<CONF_load_modules_file(3)|CONF_load_modules_file(3)>,
76L<CONF_modules_free(3)|CONF_modules_free(3)>
77
78=head1 HISTORY
79
80OPENSSL_config() and OPENSSL_no_config() first appeared in OpenSSL 0.9.7
81
82=cut
83