OPENSSL-CORE.H(7SSL) OpenSSL OPENSSL-CORE.H(7SSL)
NAME
openssl/core.h - OpenSSL Core types
SYNOPSIS
#include <openssl/core.h>
DESCRIPTION
The <openssl/core.h> header defines a number of public types that are
used to communicate between the OpenSSL libraries and implementation
providers. These types are designed to minimise the need for intimate
knowledge of internal structures between the OpenSSL libraries and the
providers.
The types are:
OSSL_DISPATCH
This type is a tuple of function identity and function pointer.
Arrays of this type are passed between the OpenSSL libraries and
the providers to describe what functionality one side provides to
the other. Arrays of this type must be terminated with a tuple
having function identity zero and function pointer NULL.
The available function identities and corresponding function
signatures are defined in openssl-core_dispatch.h(7).
Any function identity not recognised by the recipient of this type
will be ignored. This ensures that providers built with one
OpenSSL version in mind will work together with any other OpenSSL
version that supports this mechanism.
OSSL_ITEM
This type is a tuple of integer and pointer. It's a generic type
used as a generic descriptor, its exact meaning being defined by
how it's used. Arrays of this type are passed between the OpenSSL
libraries and the providers, and must be terminated with a tuple
where the integer is zero and the pointer NULL.
OSSL_ALGORITHM
This type is a tuple of an algorithm name (string), a property
definition (string) and a dispatch table (array of OSSL_DISPATCH).
Arrays of this type are passed on demand from the providers to the
OpenSSL libraries to describe what algorithms the providers provide
implementations of, and with what properties. Arrays of this type
must be terminated with a tuple having function identity zero and
function pointer NULL.
The algorithm names and property definitions are defined by the
providers.
The OpenSSL libraries use the first of the algorithm names as the
main or canonical name, on a per algorithm implementation basis.
OSSL_PARAM
This type is a structure that allows passing arbitrary object data
between two parties that have no or very little shared knowledge
about their respective internal structures for that object. It's
normally passed in arrays, where the array is terminated with an
element where all fields are zero (for non-pointers) or NULL (for
pointers).
These arrays can be used to set parameters for some object, to
request parameters, and to describe parameters.
OSSL_PARAM is further described in OSSL_PARAM(3)
OSSL_CALLBACK
This is a function type for a generic feedback callback function:
typedef int (OSSL_CALLBACK)(const OSSL_PARAM params[], void *arg);
A function that takes a pointer of this type should also take a
pointer to caller data. When calling this callback, the function
is expected to build an OSSL_PARAM array of data it wants or is
expected to pass back, and pass that as params, as well as the
caller data pointer it received, as arg.
OSSL_PASSPHRASE_CALLBACK
This is a function type for a generic pass phrase callback
function:
typedef int (OSSL_PASSPHRASE_CALLBACK)(char *pass, size_t pass_size,
size_t *pass_len,
const OSSL_PARAM params[],
void *arg);
This callback can be used to prompt the user for a passphrase.
When calling it, 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 array
params.
A function that takes a pointer of this type should also take a
pointer to caller data, which should be passed as arg to this
callback.
SEE ALSO
openssl-core_dispatch.h(7)
HISTORY
The types described here were added in OpenSSL 3.0.
COPYRIGHT
Copyright 2019-2021 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>.
3.0.2 2024-08-20 OPENSSL-CORE.H(7SSL)
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