mirror of https://github.com/openssl/openssl.git
130 lines
4.2 KiB
Plaintext
130 lines
4.2 KiB
Plaintext
=pod
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=head1 NAME
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openssl/core.h - OpenSSL Core types
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=head1 SYNOPSIS
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#include <openssl/core.h>
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=head1 DESCRIPTION
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The F<< <openssl/core.h> >> header defines a number of public types that
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are used to communicate between the OpenSSL libraries and
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implementation providers.
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These types are designed to minimise the need for intimate knowledge
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of internal structures between the OpenSSL libraries and the providers.
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The types are:
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=over 4
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=item B<OSSL_DISPATCH>
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This type is a tuple of function identity and function pointer.
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Arrays of this type are passed between the OpenSSL libraries and the
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providers to describe what functionality one side provides to the
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other.
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Arrays of this type must be terminated with a tuple having function
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identity zero and function pointer NULL.
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The available function identities and corresponding function
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signatures are defined in L<openssl-core_dispatch.h(7)>.
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Any function identity not recognised by the recipient of this type
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will be ignored.
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This ensures that providers built with one OpenSSL version in mind
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will work together with any other OpenSSL version that supports this
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mechanism.
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=item B<OSSL_ITEM>
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This type is a tuple of integer and pointer.
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It's a generic type used as a generic descriptor, its exact meaning
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being defined by how it's used.
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Arrays of this type are passed between the OpenSSL libraries and the
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providers, and must be terminated with a tuple where the integer is
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zero and the pointer NULL.
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=item B<OSSL_ALGORITHM>
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This type is a tuple of an algorithm name (string), a property
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definition (string) and a dispatch table (array of B<OSSL_DISPATCH>).
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Arrays of this type are passed on demand from the providers to the
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OpenSSL libraries to describe what algorithms the providers provide
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implementations of, and with what properties.
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Arrays of this type must be terminated with a tuple having function
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identity zero and function pointer NULL.
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The algorithm names and property definitions are defined by the
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providers.
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=item B<OSSL_PARAM>
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This type is a structure that allows passing arbitrary object data
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between two parties that have no or very little shared knowledge about
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their respective internal structures for that object.
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It's normally passed in arrays, where the array is terminated with an
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element where all fields are zero (for non-pointers) or NULL (for
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pointers).
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These arrays can be used to set parameters for some object, to request
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parameters, and to describe parameters.
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B<OSSL_PARAM> is further described in L<OSSL_PARAM(3)>
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=item B<OSSL_CALLBACK>
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This is a function type for a generic feedback callback function:
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typedef int (OSSL_CALLBACK)(const OSSL_PARAM params[], void *arg);
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A function that takes a pointer of this type should also take a
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pointer to caller data. When calling this callback, the function is
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expected to build an B<OSSL_PARAM> array of data it wants or is
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expected to pass back, and pass that as I<params>, as well as
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the caller data pointer it received, as I<arg>.
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=item B<OSSL_PASSPHRASE_CALLBACK>
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This is a function type for a generic pass phrase callback function:
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typedef int (OSSL_PASSPHRASE_CALLBACK)(char *pass, size_t pass_size,
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size_t *pass_len,
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const OSSL_PARAM params[],
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void *arg);
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This callback can be used to prompt the user for a passphrase. When
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calling it, a buffer to store the pass phrase needs to be given with
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I<pass>, and its size with I<pass_size>. The length of the prompted
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pass phrase will be given back in I<*pass_len>.
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Additional parameters can be passed with the B<OSSL_PARAM> array
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I<params>.
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A function that takes a pointer of this type should also take a
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pointer to caller data, which should be passed as I<arg> to this
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callback.
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=back
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=head1 SEE ALSO
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L<openssl-core_dispatch.h(7)>
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=head1 HISTORY
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The types described here were added in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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