xref: /openssl/doc/man3/OSSL_DISPATCH.pod (revision da1c088f)
1=pod
2
3=head1 NAME
4
5OSSL_DISPATCH, OSSL_DISPATCH_END - OpenSSL Core type to define a dispatchable function table
6
7=head1 SYNOPSIS
8
9 #include <openssl/core.h>
10
11 typedef struct ossl_dispatch_st OSSL_DISPATCH;
12 struct ossl_dispatch_st {
13     int function_id;
14     void (*function)(void);
15 };
16
17 #define OSSL_DISPATCH_END
18
19=head1 DESCRIPTION
20
21This type is a tuple of function identity and function pointer.
22Arrays of this type are passed between the OpenSSL libraries and the
23providers to describe what functionality one side provides to the other.
24
25Arrays of this type must be terminated with the OSSL_DISPATCH_END macro.
26
27=head2 B<OSSL_DISPATCH> fields
28
29=over 4
30
31=item I<function_id>
32
33OpenSSL defined function identity of the implemented function.
34
35=item I<function>
36
37Pointer to the implemented function itself.  Despite the generic definition
38of this field, the implemented function it points to must have a function
39signature that corresponds to the I<function_id>
40
41=back
42
43Available function identities and corresponding function signatures are
44defined in L<openssl-core_dispatch.h(7)>.
45Furthermore, the chosen function identities and associated function
46signature must be chosen specifically for the operation that it's intended
47for, as determined by the intended L<OSSL_ALGORITHM(3)> array.
48
49Any function identity not recognised by the recipient of this type
50will be ignored.
51This ensures that providers built with one OpenSSL version in mind
52will work together with any other OpenSSL version that supports this
53mechanism.
54
55=begin comment RETURN VALUES doesn't make sense for a manual that only
56describes a type, but document checkers still want that section, and
57to have more than just the section title.
58
59=head1 RETURN VALUES
60
61txt
62
63=end comment
64
65=head1 SEE ALSO
66
67L<crypto(7)>, L<openssl-core_dispatch.h(7)>, L<OSSL_ALGORITHM(3)>
68
69=head1 HISTORY
70
71B<OSSL_DISPATCH> was added in OpenSSL 3.0.
72
73=head1 COPYRIGHT
74
75Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
76
77Licensed under the Apache License 2.0 (the "License").  You may not use
78this file except in compliance with the License.  You can obtain a copy
79in the file LICENSE in the source distribution or at
80L<https://www.openssl.org/source/license.html>.
81
82=cut
83