openssl/doc/man3/CONF_modules_load_file.pod
Viktor Dukhovni df1f538f28 More configurable crypto and ssl library initialization
1.  In addition to overriding the default application name,
    one can now also override the configuration file name
    and flags passed to CONF_modules_load_file().

2.  By default we still keep going when configuration file
    processing fails.  But, applications that want to be strict
    about initialization errors can now make explicit flag
    choices via non-null OPENSSL_INIT_SETTINGS that omit the
    CONF_MFLAGS_IGNORE_RETURN_CODES flag (which had so far been
    both undocumented and unused).

3.  In OPENSSL_init_ssl() do not request OPENSSL_INIT_LOAD_CONFIG
    if the options already include OPENSSL_INIT_NO_LOAD_CONFIG.

4.  Don't set up atexit() handlers when called with INIT_BASE_ONLY.

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7986)
2019-01-07 14:02:28 -05:00

144 lines
5.1 KiB
Text

=pod
=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 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 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 SEE ALSO
L<config(5)>, L<OPENSSL_config(3)>
=head1 COPYRIGHT
Copyright 2004-2017 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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>.
=cut