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=head1 NAME

CONF_modules_load_file, CONF_modules_load - OpenSSL configuration functions

=head1 SYNOPSIS

 #include <openssl/conf.h>

 int CONF_modules_load_file(const char *filename, const char *appname,

                            unsigned long flags);

 int CONF_modules_load(const CONF *cnf, const char *appname,

                       unsigned long flags);

=head1 DESCRIPTION

The function CONF_modules_load_file() configures OpenSSL using file

B<filename> and application name B<appname>. If B<filename> is NULL

the standard OpenSSL configuration file is used. If B<appname> is

NULL the standard OpenSSL application name B<openssl_conf> is used.

The behaviour can be customized using B<flags>.

CONF_modules_load() is identical to CONF_modules_load_file() except it

reads configuration information from B<cnf>.

=head1 NOTES

The following B<flags> are currently recognized:

If B<CONF_MFLAGS_IGNORE_ERRORS> is set errors returned by individual

configuration modules are ignored. If not set the first module error is

considered fatal and no further modules are loaded.

Normally any modules errors will add error information to the error queue. If

B<CONF_MFLAGS_SILENT> is set no error information is added.

If B<CONF_MFLAGS_IGNORE_RETURN_CODES> is set the function unconditionally

returns success.

This is used by default in L<OPENSSL_init_crypto(3)> to ignore any errors in

the default system-wide configuration file, as having all OpenSSL applications

fail to start when there are potentially minor issues in the file is too risky.

Applications calling B<CONF_modules_load_file> explicitly should not generally

set this flag.

If B<CONF_MFLAGS_NO_DSO> is set configuration module loading from DSOs is

disabled.

B<CONF_MFLAGS_IGNORE_MISSING_FILE> if set will make CONF_load_modules_file()

ignore missing configuration files. Normally a missing configuration file

return an error.

B<CONF_MFLAGS_DEFAULT_SECTION> if set and B<appname> is not NULL will use the

default section pointed to by B<openssl_conf> if B<appname> does not exist.

By using CONF_modules_load_file() with appropriate flags an application can

customise application configuration to best suit its needs. In some cases the

use of a configuration file is optional and its absence is not an error: in

this case B<CONF_MFLAGS_IGNORE_MISSING_FILE> would be set.

Errors during configuration may also be handled differently by different

applications. For example in some cases an error may simply print out a warning

message and the application continue. In other cases an application might

consider a configuration file error as fatal and exit immediately.

Applications can use the CONF_modules_load() function if they wish to load a

configuration file themselves and have finer control over how errors are

treated.

=head1 RETURN VALUES

These functions return 1 for success and a zero or negative value for

failure. If module errors are not ignored the return code will reflect the

return value of the failing module (this will always be zero or negative).

=head1 EXAMPLES

Load a configuration file and print out any errors and exit (missing file

considered fatal):

 if (CONF_modules_load_file(NULL, NULL, 0) <= 0) {

     fprintf(stderr, "FATAL: error loading configuration file\n");

     ERR_print_errors_fp(stderr);

     exit(1);

 }

Load default configuration file using the section indicated by "myapp",

tolerate missing files, but exit on other errors:

 if (CONF_modules_load_file(NULL, "myapp",

                            CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {

     fprintf(stderr, "FATAL: error loading configuration file\n");

     ERR_print_errors_fp(stderr);

     exit(1);

 }

Load custom configuration file and section, only print warnings on error,

missing configuration file ignored:

 if (CONF_modules_load_file("/something/app.cnf", "myapp",

                            CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {

     fprintf(stderr, "WARNING: error loading configuration file\n");

     ERR_print_errors_fp(stderr);

 }

Load and parse configuration file manually, custom error handling:

 FILE *fp;

 CONF *cnf = NULL;

 long eline;

 fp = fopen("/somepath/app.cnf", "r");

 if (fp == NULL) {

     fprintf(stderr, "Error opening configuration file\n");

     /* Other missing configuration file behaviour */

 } else {

     cnf = NCONF_new(NULL);

     if (NCONF_load_fp(cnf, fp, &eline) == 0) {

         fprintf(stderr, "Error on line %ld of configuration file\n", eline);

         ERR_print_errors_fp(stderr);

         /* Other malformed configuration file behaviour */

     } else if (CONF_modules_load(cnf, "appname", 0) <= 0) {

         fprintf(stderr, "Error configuring application\n");

         ERR_print_errors_fp(stderr);

         /* Other configuration error behaviour */

     }

     fclose(fp);

     NCONF_free(cnf);

 }

=head1 SEE ALSO

L<config(5)>, L<OPENSSL_config(3)>

=head1 COPYRIGHT

Copyright 2004-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License").  You may not use

this file except in compliance with the License.  You can obtain a copy

in the file LICENSE in the source distribution or at

L<https://www.openssl.org/source/license.html>.

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