$NetBSD: OSSL_CALLBACK.3,v 1.5 2024/09/08 13:08:26 christos Exp $
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Title "OSSL_CALLBACK 3"
way too many mistakes in technical documents.
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Title "OSSL_CALLBACK 3"
OSSL_CALLBACK 3 2024-09-03 3.0.15 OpenSSL
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NAME
OSSL_CALLBACK, OSSL_PASSPHRASE_CALLBACK - OpenSSL Core type to define callbacks
SYNOPSIS
Header "SYNOPSIS" .Vb 6
#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);
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DESCRIPTION
Header "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 4
Item "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 4
Item "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
\fIpass_size. The length of the prompted pass phrase will be given back in
\fI*pass_len.
.Sp
Additional parameters can be passed with the OSSL_PARAM\|(3) array params,
"SEE ALSO"
Header "SEE ALSO" \fBopenssl-core.h\|(7)
HISTORY
Header "HISTORY" The types described here were added in OpenSSL 3.0.
COPYRIGHT
Header "COPYRIGHT" 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>.