oracular (3) OSSL_CALLBACK.3ssl.gz

Provided by: libssl-doc_3.3.1-2ubuntu2.1_all bug

NAME
       OSSL_CALLBACK, OSSL_PASSPHRASE_CALLBACK - OpenSSL Core type to define callbacks


SYNOPSIS
        #include <openssl/core.h>
        typedef int (OSSL_CALLBACK)(const OSSL_PARAM params[], void *arg);
        typedef int (OSSL_PASSPHRASE_CALLBACK)(char *pass, size_t pass_size,
                                               size_t *pass_len,
                                               const OSSL_PARAM params[],
                                               void *arg);


DESCRIPTION
       For certain events or activities, provider functionality may need help from the application or the
       calling OpenSSL libraries themselves.  For example, user input or direct (possibly optional) user output
       could be implemented this way.

       Callback functions themselves are always provided by or through the calling OpenSSL libraries, along with
       a generic pointer to data arg.  As far as the function receiving the pointer to the function pointer and
       arg is concerned, the data that arg points at is opaque, and the pointer should simply be passed back to
       the callback function when it's called.

       OSSL_CALLBACK
           This is a generic callback function.  When calling this callback function, the caller is expected to
           build an OSSL_PARAM(3) array of data it wants or is expected to pass back, and pass that as params,
           as well as the opaque data pointer it received, as arg.

       OSSL_PASSPHRASE_CALLBACK
           This is a specialised callback function, used specifically to prompt the user for a passphrase.  When
           calling this callback function, a buffer to store the pass phrase needs to be given with pass, and
           its size with pass_size.  The length of the prompted pass phrase will be given back in *pass_len.

           Additional parameters can be passed with the OSSL_PARAM(3) array params,


SEE ALSO
       openssl-core.h(7)


HISTORY
       The types described here were added in OpenSSL 3.0.


       Copyright 2022 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>.