5 OSSL_PARAM_allocate_from_text
6 - OSSL_PARAM construction utilities
10 #include <openssl/params.h>
12 int OSSL_PARAM_allocate_from_text(OSSL_PARAM *to,
13 const OSSL_PARAM *paramdefs,
14 const char *key, const char *value,
20 With OpenSSL before version 3.0, parameters were passed down to or
21 retrieved from algorithm implementations via control functions.
22 Some of these control functions existed in variants that took string
23 parameters, for example L<EVP_PKEY_CTX_ctrl_str(3)>.
25 OpenSSL 3.0 introduces a new mechanism to do the same thing with an
26 array of parameters that contain name, value, value type and value
27 size (see L<OSSL_PARAM(3)> for more information).
29 OSSL_PARAM_allocate_from_text() uses I<key> to look up an item in
30 I<paramdefs>. If an item was found, it converts I<value> to something
31 suitable for that item's I<data_type>, and stores the result in
32 I<< to->data >> as well as its size in I<< to->data_size >>.
33 I<< to->key >> and I<< to->data_type >> are assigned the corresponding
34 values from the item that was found, and I<< to->return_size >> is set
37 I<< to->data >> is always allocated using L<OPENSSL_zalloc(3)> and
38 needs to be freed by the caller when it's not useful any more, using
41 If I<found> is not NULL, I<*found> is set to 1 if I<key> could be
42 located in I<paramdefs>, and to 0 otherwise.
44 =head2 The use of I<key> and I<value> in detail
46 OSSL_PARAM_allocate_from_text() takes note if I<key> starts with
47 "hex", and will only use the rest of I<key> to look up an item in
48 I<paramdefs> in that case. As an example, if I<key> is "hexid", "id"
49 will be looked up in I<paramdefs>.
51 When an item in I<paramdefs> has been found, I<value> is converted
52 depending on that item's I<data_type>, as follows:
56 =item B<OSSL_PARAM_INTEGER> and B<OSSL_PARAM_UNSIGNED_INTEGER>
58 If I<key> started with "hex", I<value> is assumed to contain
59 I<value_n> hexadecimal characters, which are decoded, and the
60 resulting bytes become the number stored in the I<< to->data >>
63 If I<key> didn't start with "hex", I<value> is assumed to contain
64 I<value_n> decimal characters, which are decoded, and the resulting
65 bytes become the number stored in the I<< to->data >> storage.
67 If I<value> contains characters that couldn't be decoded as
68 hexadecimal or decimal characters, OSSL_PARAM_allocate_from_text()
69 considers that an error.
71 =item B<OSSL_PARAM_UTF8_STRING>
73 If I<key> started with "hex", OSSL_PARAM_allocate_from_text()
74 considers that an error.
76 Otherwise, I<value> is considered a C string and is copied to the
77 I<< to->data >> storage.
78 On systems where the native character encoding is EBCDIC, the bytes in
79 I<< to->data >> are converted to ASCII.
81 =item B<OSSL_PARAM_OCTET_STRING>
83 If I<key> started with "hex", I<value> is assumed to contain
84 I<value_n> hexadecimal characters, which are decoded, and the
85 resulting bytes are stored in the I<< to->data >> storage.
86 If I<value> contains characters that couldn't be decoded as
87 hexadecimal or decimal characters, OSSL_PARAM_allocate_from_text()
88 considers that an error.
90 If I<key> didn't start with "hex", I<value_n> bytes from I<value> are
91 copied to the I<< to->data >> storage.
97 OSSL_PARAM_allocate_from_text() returns 1 if I<key> was found in
98 I<paramdefs> and there was no other failure, otherwise 0.
102 The parameter descriptor array comes from functions dedicated to
104 The following B<OSSL_PARAM> attributes are used:
116 All other attributes are ignored.
118 The I<data_size> attribute can be zero, meaning that the parameter it
119 describes expects arbitrary length data.
123 Code that looked like this:
125 int mac_ctrl_string(EVP_PKEY_CTX *ctx, const char *value)
128 char *stmp, *vtmp = NULL;
130 stmp = OPENSSL_strdup(value);
133 vtmp = strchr(stmp, ':');
136 rv = EVP_MAC_ctrl_str(ctx, stmp, vtmp);
144 for (i = 0; i < sk_OPENSSL_STRING_num(macopts); i++) {
145 char *macopt = sk_OPENSSL_STRING_value(macopts, i);
147 if (pkey_ctrl_string(mac_ctx, macopt) <= 0) {
149 "MAC parameter error \"%s\"\n", macopt);
150 ERR_print_errors(bio_err);
155 Can be written like this instead:
158 OPENSSL_zalloc(sizeof(*params)
159 * (sk_OPENSSL_STRING_num(opts) + 1));
160 const OSSL_PARAM *paramdefs = EVP_MAC_settable_ctx_params(mac);
162 char *opt = "<unknown>";
164 for (params_n = 0; params_n < (size_t)sk_OPENSSL_STRING_num(opts);
166 char *stmp, *vtmp = NULL;
168 opt = sk_OPENSSL_STRING_value(opts, (int)params_n);
169 if ((stmp = OPENSSL_strdup(opt)) == NULL
170 || (vtmp = strchr(stmp, ':')) == NULL)
174 if (!OSSL_PARAM_allocate_from_text(¶ms[params_n],
176 vtmp, strlen(vtmp), NULL))
179 params[params_n] = OSSL_PARAM_construct_end();
180 if (!EVP_MAC_CTX_set_params(ctx, params))
182 while (params_n-- > 0)
183 OPENSSL_free(params[params_n].data);
184 OPENSSL_free(params);
189 BIO_printf(bio_err, "MAC parameter error '%s'\n", opt);
190 ERR_print_errors(bio_err);
195 L<OSSL_PARAM(3)>, L<OSSL_PARAM_int(3)>
199 Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
201 Licensed under the Apache License 2.0 (the "License"). You may not use
202 this file except in compliance with the License. You can obtain a copy
203 in the file LICENSE in the source distribution or at
204 L<https://www.openssl.org/source/license.html>.