Replumbing: Add include/openssl/core.h, initially with core types

=pod

=head1 NAME

OSSL_PARAM - a structure to pass or request object parameters

=head1 SYNOPSIS

 #include <openssl/core.h>

 typedef struct ossl_param_st OSSL_PARAM;

 struct ossl_param_st {

     const char *key;             /* the name of the parameter */

     unsigned char data_type;     /* declare what kind of content is in buffer */

     void *buffer;                /* value being passed in or out */

     size_t buffer_size;          /* buffer size */

     size_t *return_size;         /* OPTIONAL: address to content size */

 };

=head1 DESCRIPTION

C<OSSL_PARAM> is a type that allows passing arbitrary data for some

object between two parties that have no or very little shared

knowledge about their respective internal structures for that object.

A typical usage example could be an application that wants to set some

parameters for an object, or wants to find out some parameters of an

object.

Arrays of this type can be used for two purposes:

=over 4

=item *

Setting parameters for some object.

The caller sets up the C<OSSL_PARAM> array and calls some function

(the I<setter>) that has intimate knowledge about the object that can

take the data from the C<OSSL_PARAM> array and assign them in a

suitable form for the internal structure of the object.

=item *

Request parameters of some object.

The caller (the I<requestor>) sets up the C<OSSL_PARAM> array and

calls some function (the I<responder>) that has intimate knowledge

about the object, which can take the internal data of the object and

copy (possibly convert) that to the buffers prepared by the

I<requestor>.

=back

=head2 C<OSSL_PARAM> fields

=over 4

=item C<key>

The identity of the parameter in the form of a string.

=item C<data_type>

=for comment It's still debated if this field should be present, or if

the type should always be implied by how it's used.

Either way, these data types will have to be passed together with the

names as an array of OSSL_ITEM, for discovery purposes.

The C<data_type> is a value that describes the type and organization of

the data.

See L</Supported types> below for a description of the types.

=item C<buffer>

=item C<buffer_size>

C<buffer> is a pointer to the memory where the parameter data is (when

setting parameters) or shall (when requesting parameters) be stored,

and C<buffer_size> is its size in bytes.

The organization of the data depends on the parameter type and flag.

=item C<return_size>

When an array of C<OSSL_PARAM> is used to request data, the

I<responder> must set this field to indicate the actual size of the

parameter data.

In case the C<buffer_size> is too small for the data, the I<responder>

must still set this field to indicate the minimum buffer size

required.

=back

B<NOTE:>

The key names and associated types are defined by the entity that

offers these parameters, i.e. names for parameters provided by the

OpenSSL libraries are defined by the libraries, and names for

parameters provided by providers are defined by those providers,

except for the pointer form of strings (see data type descriptions

below).

Entities that want to set or request parameters need to know what

those keys are and of what type, any functionality between those two

entities should remain oblivious and just pass the C<OSSL_PARAM> array

along.

=head2 Supported types

The C<data_type> field can be one of the following types:

=over 4

=item C<OSSL_PARAM_INTEGER>

=item C<OSSL_PARAM_UNSIGNED_INTEGER>

The parameter data is an integer (signed or unsigned) of arbitrary

length, organized in native form, i.e. most significant byte first on

Big-Endian systems, and least significant byte first on Little-Endian

systems.

=item C<OSSL_PARAM_REAL>

=for comment It's still debated if we need this or not.

The parameter data is a floating point value in native form.

=item C<OSSL_PARAM_UTF8_STRING>

The parameter data is a printable string.

=item C<OSSL_PARAM_OCTET_STRING>

The parameter data is an arbitrary string of bytes.

=back

Additionally, this flag can be added to any type:

=over 4

=item C<OSSL_PARAM_POINTER_FLAG>

With this flag, C<buffer> doesn't point directly at the data, but at a

pointer that points at the data.

This can be used to indicate that constant data is or will be passed,

and there is therefore no need to copy the data that is passed, just

the pointer to it.

If an C<OSSL_PARAM> with this flag set is used to set a parameter,

C<buffer_size> must be set to the size of the data, not the size of

the pointer to the data.

If this C<OSSL_PARAM> is used in a parameter request, C<buffer_size>

is not relevant.

However, the I<responder> will set C<*return_size> to the size of the

data (again, not the size of the pointer to the data).

Note that the use of this flag is B<fragile> and can only be safely

used for data that remains constant and in a constant location for a

long enough duration (such as the life-time of the entity that

offers these parameters).

=back

For convenience, these types are provided:

=over 4

=item C<OSSL_PARAM_UTF8_STRING_PTR>

=item C<OSSL_PARAM_OCTET_STRING_PTR>

These are combinations of C<OSSL_PARAM_UTF8_STRING> as well as

C<OSSL_PARAM_OCTET_STRING> with C<OSSL_PARAM_POINTER_FLAG>.

=back

=head1 NOTES

Both when setting and requesting parameters, the functions that are

called will have to decide what is and what is not an error.

The recommended behaviour is:

=over 4

=item *

Keys that a I<setter> or I<responder> doesn't recognise should simply

be ignored.

That in itself isn't an error.

=item *

If the keys that a called I<setter> recognises form a consistent

enough set of data, that call should succeed.

=item *

A I<responder> must never change the fields of an C<OSSL_PARAM>, it

may only change the contents of the buffers that C<buffer> and

C<return_size> point at.

=item *

If the data type for a key that it's associated with is incorrect,

the called function may return an error.

The called function may also try to convert the data to a suitable

form (for example, it's plausible to pass a large number as an octet

string, so even though a given key is defined as an

C<OSSL_PARAM_UNSIGNED_INTEGER>, is plausible to pass the value as an

C<OSSL_PARAM_OCTET_STRING>), but this is in no way mandatory.

=item *

If a I<responder> finds that some buffers are too small for the

requested data, it must set C<*return_size> for each such

C<OSSL_PARAM> item to the required size, and eventually return an

error.

=back

=begin comment RETURN VALUES doesn't make sense for a manual that only

describes a type, but document checkers still want that section, and

to have more than just the section title.

=head1 RETURN VALUES

txt

=end comment

=head1 EXAMPLES

A couple of examples to just show how C<OSSL_PARAM> arrays could be

set up.

=head3 Example 1

This example is for setting parameters on some object:

    #include <openssl/core.h>

    const char *foo = "some string";

    size_t foo_l = strlen(foo) + 1;

    const char bar[] = "some other string";

    const OSSL_PARAM set[] = {

        { "foo", OSSL_PARAM_UTF8_STRING_PTR, &foo, foo_l, NULL },

        { "bar", OSSL_PARAM_UTF8_STRING, &bar, sizeof(bar), NULL },

        { NULL, 0, NULL, 0, NULL }

    };

=head3 Example 2

This example is for requesting parameters on some object:

    const char *foo = NULL;

    size_t foo_l;

    char bar[1024];

    size_t bar_l;

    const OSSL_PARAM request[] = {

        { "foo", OSSL_PARAM_UTF8_STRING_PTR, &foo, 0 /*irrelevant*/, &foo_l },

        { "bar", OSSL_PARAM_UTF8_STRING, &bar, sizeof(bar), &bar_l },

        { NULL, 0, NULL, 0, NULL }

    };

A I<responder> that receives this array (as C<params> in this example)

could fill in the parameters like this:

    /* const OSSL_PARAM *params */

    int i;

    for (i = 0; params[i].key != NULL; i++) {

        if (strcmp(params[i].key, "foo") == 0) {

            *(char **)params[i].buffer = "foo value";

            *params[i].return_size = 10; /* size of "foo value" */

        } else if (strcmp(params[i].key, "bar") == 0) {

            memcpy(params[1].buffer, "bar value", 10);

            *params[1].return_size = 10; /* size of "bar value" */

        }

        /* Ignore stuff we don't know */

    }

=head1 SEE ALSO

L<openssl-core.h(7)>

=head1 HISTORY

C<OSSL_PARAM> was added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2019 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

L<https://www.openssl.org/source/license.html>.

=cut

=pod

=head1 NAME

openssl/core.h - OpenSSL Core types

=head1 SYNOPSIS

 #include <openssl/core.h>

=head1 DESCRIPTION

The <openssl/core.h> header file 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:

=over 4

=item C<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 C<NULL>.

The available function identities and corresponding function

signatures are defined by L<openssl-core_numbers.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.

=item C<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 C<NULL>.

=item C<OSSL_ALGORITHM>

This type is a tuple of an algorithm name (string), a property

definition (string) and a dispatch table (array of C<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 C<NULL>.

The algorithm names and property definitions are defined by the

providers.

=item C<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 C<NULL> (for

pointers).

These arrays can be used both to set parameters for some object, and

to request parameters.

C<OSSL_PARAM> is further described in L<OSSL_PARAM(3)>

=back

=head1 SEE ALSO

L<openssl-core_numbers.h(7)>

=head1 HISTORY

The types described here were added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2019 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

L<https://www.openssl.org/source/license.html>.

=cut

/*

 * Copyright 2019 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

 */

#ifndef OSSL_CORE_H

# define OSSL_CORE_H

# include <stddef.h>

# include <openssl/ossl_typ.h>

# ifdef __cplusplus

extern "C" {

# endif

/*-

 * Base types

 * ----------

 *

 * These are the types that the OpenSSL core and providers have in common

 * to communicate data between them.

 */

/*

 * Dispatch table element.  function_id numbers are defined further down,

 * see macros with '_FUNC' in their names.

 *

 * An array of these is always terminated by function_id == 0

 */

struct ossl_dispatch_st {

    int function_id;

    void (*function)(void);

};

/*

 * Other items, essentially an int<->pointer map element.

 *

 * We make this type distinct from OSSL_DISPATCH to ensure that dispatch

 * tables remain tables with function pointers only.

 *

 * This is used whenever we need to pass things like a table of error reason

 * codes <-> reason string maps, parameter name <-> parameter type maps, ...

 *

 * Usage determines which field works as key if any, rather than field order.

 *

 * An array of these is always terminated by id == 0 && ptr == NULL

 */

struct ossl_item_st {

    unsigned int id;

    void *ptr;

};

/*

 * Type to tie together algorithm name, property definition string and

 * the algorithm implementation in the form of a dispatch table.

 *

 * An array of these is always terminated by algorithm_name == NULL

 */

struct ossl_algorithm_st {

    const char *algorithm_name;      /* key */

    const char *property_definition; /* key */

    const OSSL_DISPATCH *implementation;

};

/*

 * Type to pass object data in a uniform way, without exposing the object

 * structure.

 *

 * An array of these is always terminated by key == NULL

 */

struct ossl_param_st {

    const char *key;             /* the name of the parameter */

    unsigned int data_type;      /* declare what kind of content is in buffer */

    void *buffer;                /* value being passed in or out */

    size_t buffer_size;          /* buffer size */

    size_t *return_size;         /* OPTIONAL: address to content size */

};

/* Currently supported OSSL_PARAM data types */

/*

 * OSSL_PARAM_INTEGER and OSSL_PARAM_UNSIGNED_INTEGER

 * are arbitrary length and therefore require an arbitrarily sized buffer,

 * since they may be used to pass numbers larger than what is natively

 * available.

 *

 * The number must be buffered in native form, i.e. MSB first on B_ENDIAN

 * systems and LSB first on L_ENDIAN systems.  This means that arbitrary

 * native integers can be stored in the buffer, just make sure that the

 * buffer size is correct and the buffer itself is properly aligned (for

 * example by having the buffer field point at a C integer).

 */

# define OSSL_PARAM_INTEGER              1

# define OSSL_PARAM_UNSIGNED_INTEGER     2

/*-

 * OSSL_PARAM_REAL

 * is a C binary floating point values in native form and alignment.

 */

# define OSSL_PARAM_REAL                 3

/*-

 * OSSL_PARAM_UTF8_STRING

 * is a printable string.  Is expteced to be printed as it is.

 */

# define OSSL_PARAM_UTF8_STRING          4

/*-

 * OSSL_PARAM_OCTET_STRING

 * is a string of bytes with no further specification.  Is expected to be

 * printed as a hexdump.

 */

# define OSSL_PARAM_OCTET_STRING         5

/*-

 * Pointer flag

 *

 * This flag can be added to any type to signify that the buffer

 * pointer is set to point at a pointer to the data instead of

 * pointing directly at the data.

 *

 * This is more relevant for parameter requests, where the responding

 * function doesn't need to copy the data to the provided buffer, but

 * sets the provided buffer to point at the actual data instead.

 *

 * WARNING!  Using these is FRAGILE, as it assumes that the actual

 * data and its location are constant.

 */

# define OSSL_PARAM_POINTER_FLAG    0x80000000UL

/*

 * Convenience pointer types for strings.

 */

# define OSSL_PARAM_UTF8_STRING_PTR                     \

    (OSSL_PARAM_UTF8_STRING|OSSL_PARAM_POINTER_FLAG)

# define OSSL_PARAM_OCTET_STRING_PTR                    \

    (OSSL_PARAM_OCTET_STRING|OSSL_PARAM_POINTER_FLAG)

# ifdef __cplusplus

}

# endif

#endif

typedef struct openssl_ctx_st OPENSSL_CTX;

typedef struct ossl_dispatch_st OSSL_DISPATCH;

typedef struct ossl_item_st OSSL_ITEM;

typedef struct ossl_algorithm_st OSSL_ALGORITHM;

typedef struct ossl_param_st OSSL_PARAM;

#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L && \

    defined(INTMAX_MAX) && defined(UINTMAX_MAX)

typedef intmax_t ossl_intmax_t;

OPENSSL_Applink                         external

OPENSSL_CTX                             datatype

NAMING_AUTHORITY                        datatype

OSSL_PARAM                              datatype

OSSL_STORE_CTX                          datatype

OSSL_STORE_INFO                         datatype

OSSL_STORE_LOADER                       datatype