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 with no
77 further checks to the I<< to->data >> storage.
79 =item B<OSSL_PARAM_OCTET_STRING>
81 If I<key> started with "hex", I<value> is assumed to contain
82 I<value_n> hexadecimal characters, which are decoded, and the
83 resulting bytes are stored in the I<< to->data >> storage.
84 If I<value> contains characters that couldn't be decoded as
85 hexadecimal or decimal characters, OSSL_PARAM_allocate_from_text()
86 considers that an error.
88 If I<key> didn't start with "hex", I<value_n> bytes from I<value> are
89 copied to the I<< to->data >> storage.
95 OSSL_PARAM_allocate_from_text() returns 1 if I<key> was found in
96 I<paramdefs> and there was no other failure, otherwise 0.
100 The parameter descriptor array comes from functions dedicated to
102 The following B<OSSL_PARAM> attributes are used:
114 All other attributes are ignored.
116 The I<data_size> attribute can be zero, meaning that the parameter it
117 describes expects arbitrary length data.
121 Code that looked like this:
123 int mac_ctrl_string(EVP_PKEY_CTX *ctx, const char *value)
126 char *stmp, *vtmp = NULL;
128 stmp = OPENSSL_strdup(value);
131 vtmp = strchr(stmp, ':');
134 rv = EVP_MAC_ctrl_str(ctx, stmp, vtmp);
142 for (i = 0; i < sk_OPENSSL_STRING_num(macopts); i++) {
143 char *macopt = sk_OPENSSL_STRING_value(macopts, i);
145 if (pkey_ctrl_string(mac_ctx, macopt) <= 0) {
147 "MAC parameter error \"%s\"\n", macopt);
148 ERR_print_errors(bio_err);
153 Can be written like this instead:
156 OPENSSL_zalloc(sizeof(*params)
157 * (sk_OPENSSL_STRING_num(opts) + 1));
158 const OSSL_PARAM *paramdefs = EVP_MAC_settable_ctx_params(mac);
160 char *opt = "<unknown>";
162 for (params_n = 0; params_n < (size_t)sk_OPENSSL_STRING_num(opts);
164 char *stmp, *vtmp = NULL;
166 opt = sk_OPENSSL_STRING_value(opts, (int)params_n);
167 if ((stmp = OPENSSL_strdup(opt)) == NULL
168 || (vtmp = strchr(stmp, ':')) == NULL)
172 if (!OSSL_PARAM_allocate_from_text(¶ms[params_n],
174 vtmp, strlen(vtmp), NULL))
177 params[params_n] = OSSL_PARAM_construct_end();
178 if (!EVP_MAC_CTX_set_params(ctx, params))
180 while (params_n-- > 0)
181 OPENSSL_free(params[params_n].data);
182 OPENSSL_free(params);
187 BIO_printf(bio_err, "MAC parameter error '%s'\n", opt);
188 ERR_print_errors(bio_err);
193 L<OSSL_PARAM(3)>, L<OSSL_PARAM_int(3)>
197 Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
199 Licensed under the Apache License 2.0 (the "License"). You may not use
200 this file except in compliance with the License. You can obtain a copy
201 in the file LICENSE in the source distribution or at
202 L<https://www.openssl.org/source/license.html>.