1OPENSSL_config(3) OpenSSL OPENSSL_config(3)
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6 OPENSSL_config, OPENSSL_no_config - simple OpenSSL configuration func‐
7 tions
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10 #include <openssl/conf.h>
11 void OPENSSL_config(const char *config_name);
13 void OPENSSL_no_config(void);
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16 OPENSSL_config() configures OpenSSL using the standard openssl.cnf con‐
17 figuration file name using config_name. If config_name is NULL then the
18 default name openssl_conf will be used. Any errors are ignored. Further
19 calls to OPENSSL_config() will have no effect. The configuration file
20 format is documented in the conf(5) manual page.
21 OPENSSL_no_config() disables configuration. If called before
23 OPENSSL_config() no configuration takes place.
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26 It is strongly recommended that all new applications call OPENSSL_con‐
27 fig() or the more sophisticated functions such as CONF_modules_load()
28 during initialization (that is before starting any threads). By doing
29 this an application does not need to keep track of all configuration
30 options and some new functionality can be supported automatically.
31 It is also possible to automatically call OPENSSL_config() when an
33 application calls OPENSSL_add_all_algorithms() by compiling an applica‐
34 tion with the preprocessor symbol OPENSSL_LOAD_CONF #define'd. In this
35 way configuration can be added without source changes.
36 The environment variable OPENSSL_CONF can be set to specify the loca‐
38 tion of the configuration file.
39 Currently ASN1 OBJECTs and ENGINE configuration can be performed future
41 versions of OpenSSL will add new configuration options.
42 There are several reasons why calling the OpenSSL configuration rou‐
44 tines is advisable. For example new ENGINE functionality was added to
45 OpenSSL 0.9.7. In OpenSSL 0.9.7 control functions can be supported by
46 ENGINEs, this can be used (among other things) to load dynamic ENGINEs
47 from shared libraries (DSOs). However very few applications currently
48 support the control interface and so very few can load and use dynamic
49 ENGINEs. Equally in future more sophisticated ENGINEs will require cer‐
50 tain control operations to customize them. If an application calls
51 OPENSSL_config() it doesn't need to know or care about ENGINE control
52 operations because they can be performed by editing a configuration
53 file.
54 Applications should free up configuration at application closedown by
56 calling CONF_modules_free().
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59 The OPENSSL_config() function is designed to be a very simple "call it
60 and forget it" function. As a result its behaviour is somewhat limited.
61 It ignores all errors silently and it can only load from the standard
62 configuration file location for example.
63 It is however much better than nothing. Applications which need finer
65 control over their configuration functionality should use the configu‐
66 ration functions such as CONF_load_modules() directly.
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69 Neither OPENSSL_config() nor OPENSSL_no_config() return a value.
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72 conf(5), CONF_load_modules_file(3), CONF_modules_free(3),CONF_mod‐
73 ules_free(3)
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76 OPENSSL_config() and OPENSSL_no_config() first appeared in OpenSSL
77 0.9.7
780.9.8b 2005-06-02 OPENSSL_config(3)