5 evp_generic_fetch - generic algorithm fetcher and method creator for EVP
9 /* Only for EVP source */
12 void *evp_generic_fetch(OPENSSL_CTX *libctx, int operation_id,
13 const char *algorithm, const char *properties,
14 void *(*new_method)(int nid, const OSSL_DISPATCH *fns,
16 int (*upref_method)(void *),
17 void (*free_method)(void *));
21 evp_generic_fetch() calls ossl_method_construct() with the given
22 C<libctx>, C<operation_id>, C<algorithm>, and C<properties> and uses
23 it to create an EVP method with the help of the functions
24 C<new_method>, C<upref_method>, and C<free_method>.
26 The three functions are supposed to:
32 creates an internal method from function pointers found in the
33 dispatch table C<fns>.
37 increments the reference counter for the given method, if there is
42 frees the given method.
48 evp_generic_fetch() returns a method on success, or B<NULL> on error.
52 This is a short example of the fictitious EVP API and operation called
55 To begin with, let's assume something like this in
56 C<include/openssl/core_numbers.h>:
58 #define OSSL_OP_FOO 100
60 #define OSSL_OP_FOO_NEWCTX_FUNC 2001
61 #define OSSL_OP_FOO_INIT 2002
62 #define OSSL_OP_FOO_OPERATE 2003
63 #define OSSL_OP_FOO_CLEANCTX_FUNC 2004
64 #define OSSL_OP_FOO_FREECTX_FUNC 2005
65 OSSL_CORE_MAKE_FUNC(void *,OP_foo_newctx,(void))
66 OSSL_CORE_MAKE_FUNC(int,OP_foo_init,(void *vctx))
67 OSSL_CORE_MAKE_FUNC(int,OP_foo_operate,(void *vctx,
68 unsigned char *out, size_t *out_l,
69 unsigned char *in, size_t in_l))
70 OSSL_CORE_MAKE_FUNC(void,OP_foo_cleanctx,(void *vctx))
71 OSSL_CORE_MAKE_FUNC(void,OP_foo_freectx,(void *vctx))
73 And here's the implementation of the FOO method fetcher:
75 /* typedef struct evp_foo_st EVP_FOO */
79 CRYPTO_REF_COUNT refcnt;
80 OSSL_OP_foo_newctx_fn *newctx;
81 OSSL_OP_foo_init_fn *init;
82 OSSL_OP_foo_operate_fn *operate;
83 OSSL_OP_foo_cleanctx_fn *cleanctx;
84 OSSL_OP_foo_freectx_fn *freectx;
88 * In this example, we have a public method creator and destructor.
89 * It's not absolutely necessary, but is in the spirit of OpenSSL.
91 EVP_FOO *EVP_FOO_meth_from_dispatch(int foo_type, const OSSL_DISPATCH *fns,
96 if ((foo = OPENSSL_zalloc(sizeof(*foo))) == NULL)
99 for (; fns->function_id != 0; fns++) {
100 switch (fns->function_id) {
101 case OSSL_OP_FOO_NEWCTX_FUNC:
102 foo->newctx = OSSL_get_OP_foo_newctx(fns);
104 case OSSL_OP_FOO_INIT:
105 foo->init = OSSL_get_OP_foo_init(fns);
107 case OSSL_OP_FOO_OPERATE:
108 foo->operate = OSSL_get_OP_foo_operate(fns);
110 case OSSL_OP_FOO_CLEANCTX_FUNC:
111 foo->cleanctx = OSSL_get_OP_foo_cleanctx(fns);
113 case OSSL_OP_FOO_FREECTX_FUNC:
114 foo->freectx = OSSL_get_OP_foo_freectx(fns);
121 ossl_provider_upref(prov);
126 EVP_FOO_meth_free(EVP_FOO *foo)
129 OSSL_PROVIDER *prov = foo->prov;
132 ossl_provider_free(prov);
136 static void *foo_from_dispatch(int nid, const OSSL_DISPATCH *fns,
139 return EVP_FOO_meth_from_dispatch(nid, fns, prov);
142 static int foo_upref(void *vfoo)
147 CRYPTO_UP_REF(&foo->refcnt, &ref, foo_lock);
151 static void foo_free(void *vfoo)
153 EVP_FOO_meth_free(vfoo);
156 EVP_FOO *EVP_FOO_fetch(OPENSSL_CTX *ctx,
157 const char *algorithm,
158 const char *properties)
160 return evp_generic_fetch(ctx, OSSL_OP_FOO, algorithm, properties,
161 foo_from_dispatch, foo_upref, foo_free);
164 And finally, the library functions:
166 /* typedef struct evp_foo_st EVP_FOO_CTX */
167 struct evp_foo_ctx_st {
169 void *provctx; /* corresponding provider context */
172 int EVP_FOO_CTX_reset(EVP_FOO_CTX *c)
176 if (c->foo != NULL && c->foo->cleanctx != NULL)
177 c->foo->cleanctx(c->provctx);
181 EVP_FOO_CTX *EVP_FOO_CTX_new(void)
183 return OPENSSL_zalloc(sizeof(EVP_FOO_CTX));
186 void EVP_FOO_CTX_free(EVP_FOO_CTX *c)
188 EVP_FOO_CTX_reset(c);
189 c->foo->freectx(c->provctx);
193 int EVP_FooInit(EVP_FOO_CTX *c, const EVP_FOO *foo)
198 if (c->provctx == NULL)
199 c->provctx = c->foo->newctx();
201 ok = c->foo->init(c->provctx);
206 int EVP_FooOperate(EVP_FOO_CTX *c, unsigned char *out, size_t *outl,
207 const unsigned char *in, size_t inl)
211 ok = c->foo->update(c->provctx, out, inl, &outl, in, inl);
217 L<ossl_method_construct>
221 The functions described here were all added in OpenSSL 3.0.
225 Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
227 Licensed under the Apache License 2.0 (the "License"). You may not use
228 this file except in compliance with the License. You can obtain a copy
229 in the file LICENSE in the source distribution or at
230 L<https://www.openssl.org/source/license.html>.