NAME

       OPENSSL_init_ssl - OpenSSL (libssl and libcrypto) initialisation

SYNOPSIS

        #include <openssl/ssl.h>

        int OPENSSL_init_ssl(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings);

DESCRIPTION

       During normal operation OpenSSL (libssl and libcrypto) will allocate various resources at
       start up that must, subsequently, be freed on close down of the library. Additionally some
       resources are allocated on a per thread basis (if the application is multi-threaded), and
       these resources must be freed prior to the thread closing.

       As of version 1.1.0 OpenSSL will automatically allocate all resources that it needs so no
       explicit initialisation is required. Similarly it will also automatically deinitialise as
       required.

       However, there may be situations when explicit initialisation is desirable or needed, for
       example when some nondefault initialisation is required. The function OPENSSL_init_ssl()
       can be used for this purpose. Calling this function will explicitly initialise BOTH
       libcrypto and libssl. To explicitly initialise ONLY libcrypto see the
       OPENSSL_init_crypto(3) function.

       Numerous internal OpenSSL functions call OPENSSL_init_ssl().  Therefore, in order to
       perform nondefault initialisation, OPENSSL_init_ssl() MUST be called by application code
       prior to any other OpenSSL function calls.

       The opts parameter specifies which aspects of libssl and libcrypto should be initialised.
       Valid options for libcrypto are described on the OPENSSL_init_crypto(3) page. In addition
       to any libcrypto specific option the following libssl options can also be used:

       OPENSSL_INIT_NO_LOAD_SSL_STRINGS
           Suppress automatic loading of the libssl error strings. This option is not a default
           option. Once selected subsequent calls to OPENSSL_init_ssl() with the option
           OPENSSL_INIT_LOAD_SSL_STRINGS will be ignored.

       OPENSSL_INIT_LOAD_SSL_STRINGS
           Automatic loading of the libssl error strings. This option is a default option. Once
           selected subsequent calls to OPENSSL_init_ssl() with the option
           OPENSSL_INIT_LOAD_SSL_STRINGS will be ignored.

       OPENSSL_init_ssl() takes a settings parameter which can be used to set parameter values.
       See OPENSSL_init_crypto(3) for details.

RETURN VALUES

       The function OPENSSL_init_ssl() returns 1 on success or 0 on error.

SEE ALSO

       OPENSSL_init_crypto(3)

HISTORY

       The OPENSSL_init_ssl() function was added in OpenSSL 1.1.0.

COPYRIGHT

       Copyright 2016-2020 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 <https://www.openssl.org/source/license.html>.