=pod

=head1 NAME

X509_get_default_cert_file, X509_get_default_cert_file_env,
X509_get_default_cert_dir, X509_get_default_cert_dir_env -
retrieve default locations for trusted CA certificates

=head1 SYNOPSIS

 #include <openssl/x509.h>

 const char *X509_get_default_cert_file(void);
 const char *X509_get_default_cert_dir(void);

 const char *X509_get_default_cert_file_env(void);
 const char *X509_get_default_cert_dir_env(void);

=head1 DESCRIPTION

The X509_get_default_cert_file() function returns the default path
to a file containing trusted CA certificates. OpenSSL will use this as
the default path when it is asked to load trusted CA certificates
from a file and no other path is specified. If the file exists, CA certificates
are loaded from the file.

The X509_get_default_cert_dir() function returns a default delimeter-separated
list of paths to a directories containing trusted CA certificates named in the
hashed format. OpenSSL will use this as the default list of paths when it is
asked to load trusted CA certificates from a directory and no other path is
specified. If a given directory in the list exists, OpenSSL attempts to lookup
CA certificates in this directory by calculating a filename based on a hash of
the certificate's subject name.

X509_get_default_cert_file_env() returns an environment variable name which is
recommended to specify a nondefault value to be used instead of the value
returned by X509_get_default_cert_file(). The value returned by the latter
function is not affected by these environment variables; you must check for this
environment variable yourself, using this function to retrieve the correct
environment variable name. If an environment variable is not set, the value
returned by the X509_get_default_cert_file() should be used.

X509_get_default_cert_dir_env() returns the environment variable name which is
recommended to specify a nondefault value to be used instead of the value
returned by X509_get_default_cert_dir(). The value specified by this environment
variable can also be a store URI (but see BUGS below).

=head1 BUGS

By default (for example, when L<X509_STORE_set_default_paths(3)> is used), the
environment variable name returned by X509_get_default_cert_dir_env() is
interpreted both as a delimiter-separated list of paths, and as a store URI.
This is ambiguous. For example, specifying a value of B<"file:///etc/certs">
would cause instantiation of the "file" store provided as part of the default
provider, but would also cause an L<X509_LOOKUP_hash_dir(3)> instance to look
for certificates in the directory B<"file"> (relative to the current working
directory) and the directory B<"///etc/certs">. This can be avoided by avoiding
use of the environment variable mechanism and using other methods to construct
X509_LOOKUP instances.

=head1 RETURN VALUES

These functions return pointers to constant strings with static storage
duration.

=head1 SEE ALSO

L<X509_LOOKUP(3)>,
L<SSL_CTX_set_default_verify_file(3)>,
L<SSL_CTX_set_default_verify_dir(3)>,
L<SSL_CTX_set_default_verify_store(3)>,
L<SSL_CTX_load_verify_file(3)>,
L<SSL_CTX_load_verify_dir(3)>,
L<SSL_CTX_load_verify_store(3)>,
L<SSL_CTX_load_verify_locations(3)>

=head1 COPYRIGHT

Copyright 2022-2023 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
