83 lines
3.1 KiB
Plaintext
83 lines
3.1 KiB
Plaintext
=pod
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=head1 NAME
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OPENSSL_config, OPENSSL_no_config - simple OpenSSL configuration functions
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=head1 SYNOPSIS
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#include <openssl/conf.h>
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void OPENSSL_config(const char *config_name);
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void OPENSSL_no_config(void);
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=head1 DESCRIPTION
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OPENSSL_config() configures OpenSSL using the standard B<openssl.cnf>
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configuration file name using B<config_name>. If B<config_name> is NULL then
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the default name B<openssl_conf> will be used. Any errors are ignored. Further
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calls to OPENSSL_config() will have no effect. The configuration file format
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is documented in the L<conf(5)|conf(5)> manual page.
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OPENSSL_no_config() disables configuration. If called before OPENSSL_config()
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no configuration takes place.
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=head1 NOTES
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It is B<strongly> recommended that B<all> new applications call OPENSSL_config()
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or the more sophisticated functions such as CONF_modules_load() during
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initialization (that is before starting any threads). By doing this
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an application does not need to keep track of all configuration options
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and some new functionality can be supported automatically.
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It is also possible to automatically call OPENSSL_config() when an application
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calls OPENSSL_add_all_algorithms() by compiling an application with the
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preprocessor symbol B<OPENSSL_LOAD_CONF> #define'd. In this way configuration
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can be added without source changes.
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The environment variable B<OPENSSL_CONF> can be set to specify the location
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of the configuration file.
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Currently ASN1 OBJECTs and ENGINE configuration can be performed future
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versions of OpenSSL will add new configuration options.
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There are several reasons why calling the OpenSSL configuration routines is
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advisable. For example new ENGINE functionality was added to OpenSSL 0.9.7.
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In OpenSSL 0.9.7 control functions can be supported by ENGINEs, this can be
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used (among other things) to load dynamic ENGINEs from shared libraries (DSOs).
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However very few applications currently support the control interface and so
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very few can load and use dynamic ENGINEs. Equally in future more sophisticated
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ENGINEs will require certain control operations to customize them. If an
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application calls OPENSSL_config() it doesn't need to know or care about
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ENGINE control operations because they can be performed by editing a
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configuration file.
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Applications should free up configuration at application closedown by calling
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CONF_modules_free().
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=head1 RESTRICTIONS
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The OPENSSL_config() function is designed to be a very simple "call it and
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forget it" function. As a result its behaviour is somewhat limited. It ignores
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all errors silently and it can only load from the standard configuration file
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location for example.
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It is however B<much> better than nothing. Applications which need finer
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control over their configuration functionality should use the configuration
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functions such as CONF_load_modules() directly.
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=head1 RETURN VALUES
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Neither OPENSSL_config() nor OPENSSL_no_config() return a value.
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=head1 SEE ALSO
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L<conf(5)|conf(5)>, L<CONF_load_modules_file(3)|CONF_load_modules_file(3)>,
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L<CONF_modules_free(3),CONF_modules_free(3)>
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=head1 HISTORY
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OPENSSL_config() and OPENSSL_no_config() first appeared in OpenSSL 0.9.7
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=cut
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