xref: /openssl/doc/man3/OSSL_STORE_open.pod (revision 556009c5) 
1=pod
2
3=head1 NAME
4
5OSSL_STORE_CTX, OSSL_STORE_post_process_info_fn,
6OSSL_STORE_open, OSSL_STORE_open_ex,
7OSSL_STORE_ctrl, OSSL_STORE_load, OSSL_STORE_eof, OSSL_STORE_delete,
8OSSL_STORE_error, OSSL_STORE_close
9- Types and functions to read objects from a URI
10
11=head1 SYNOPSIS
12
13 #include <openssl/store.h>
14
15 typedef struct ossl_store_ctx_st OSSL_STORE_CTX;
16
17 typedef OSSL_STORE_INFO *(*OSSL_STORE_post_process_info_fn)(OSSL_STORE_INFO *,
18                                                             void *);
19
20 OSSL_STORE_CTX *OSSL_STORE_open(const char *uri, const UI_METHOD *ui_method,
21                                 void *ui_data,
22                                 OSSL_STORE_post_process_info_fn post_process,
23                                 void *post_process_data);
24 OSSL_STORE_CTX *
25 OSSL_STORE_open_ex(const char *uri, OSSL_LIB_CTX *libctx, const char *propq,
26                    const UI_METHOD *ui_method, void *ui_data,
27                    const OSSL_PARAM params[],
28                    OSSL_STORE_post_process_info_fn post_process,
29                    void *post_process_data);
30
31 OSSL_STORE_INFO *OSSL_STORE_load(OSSL_STORE_CTX *ctx);
32 int OSSL_STORE_eof(OSSL_STORE_CTX *ctx);
33 int OSSL_STORE_delete(const char *uri, OSSL_LIB_CTX *libctx, const char *propq,
34                       const UI_METHOD *ui_method, void *ui_data,
35                       const OSSL_PARAM params[]);
36 int OSSL_STORE_error(OSSL_STORE_CTX *ctx);
37 int OSSL_STORE_close(OSSL_STORE_CTX *ctx);
38
39The following function has been deprecated since OpenSSL 3.0, and can be
40hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
41see L<openssl_user_macros(7)>:
42
43 int OSSL_STORE_ctrl(OSSL_STORE_CTX *ctx, int cmd, ... /* args */);
44
45=head1 DESCRIPTION
46
47These functions help the application to fetch supported objects (see
48L<OSSL_STORE_INFO(3)/SUPPORTED OBJECTS> for information on which those are)
49from a given URI.
50The general method to do so is to "open" the URI using OSSL_STORE_open(),
51read each available and supported object using OSSL_STORE_load() as long as
52OSSL_STORE_eof() hasn't been reached, and finish it off with OSSL_STORE_close().
53
54The retrieved information is stored in a B<OSSL_STORE_INFO>, which is further
55described in L<OSSL_STORE_INFO(3)>.
56
57=head2 Types
58
59B<OSSL_STORE_CTX> is a context variable that holds all the internal
60information for OSSL_STORE_open(), OSSL_STORE_open_ex(),
61OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close() to work
62together.
63
64=head2 Functions
65
66OSSL_STORE_open_ex() takes a uri or path I<uri>, password UI method
67I<ui_method> with associated data I<ui_data>, and post processing
68callback I<post_process> with associated data I<post_process_data>,
69a library context I<libctx> with an associated property query I<propq>,
70and opens a channel to the data located at the URI and returns a
71B<OSSL_STORE_CTX> with all necessary internal information.
72The given I<ui_method> and I<ui_data> will be reused by all
73functions that use B<OSSL_STORE_CTX> when interaction is needed,
74for instance to provide a password.
75The auxiliary L<OSSL_PARAM(3)> parameters in I<params> can be set to further
76modify the store operation.
77The given I<post_process> and I<post_process_data> will be reused by
78OSSL_STORE_load() to manipulate or drop the value to be returned.
79The I<post_process> function drops values by returning NULL, which
80will cause OSSL_STORE_load() to start its process over with loading
81the next object, until I<post_process> returns something other than
82NULL, or the end of data is reached as indicated by OSSL_STORE_eof().
83
84OSSL_STORE_open() is similar to OSSL_STORE_open_ex() but uses NULL for
85the I<params>, the library context I<libctx> and property query I<propq>.
86
87OSSL_STORE_ctrl() takes a B<OSSL_STORE_CTX>, and command number I<cmd> and
88more arguments not specified here.
89The available loader specific command numbers and arguments they each
90take depends on the loader that's used and is documented together with
91that loader.
92
93There are also global controls available:
94
95=over 4
96
97=item B<OSSL_STORE_C_USE_SECMEM>
98
99Controls if the loader should attempt to use secure memory for any
100allocated B<OSSL_STORE_INFO> and its contents.
101This control expects one argument, a pointer to an I<int> that is expected to
102have the value 1 (yes) or 0 (no).
103Any other value is an error.
104
105=back
106
107OSSL_STORE_load() takes a B<OSSL_STORE_CTX> and tries to load the next
108available object and return it wrapped with B<OSSL_STORE_INFO>.
109
110OSSL_STORE_delete() deletes the object identified by I<uri>.
111
112OSSL_STORE_eof() takes a B<OSSL_STORE_CTX> and checks if we've reached the end
113of data.
114
115OSSL_STORE_error() takes a B<OSSL_STORE_CTX> and checks if an error occurred in
116the last OSSL_STORE_load() call.
117Note that it may still be meaningful to try and load more objects, unless
118OSSL_STORE_eof() shows that the end of data has been reached.
119
120OSSL_STORE_close() takes a B<OSSL_STORE_CTX>, closes the channel that was opened
121by OSSL_STORE_open() and frees all other information that was stored in the
122B<OSSL_STORE_CTX>, as well as the B<OSSL_STORE_CTX> itself.
123If I<ctx> is NULL it does nothing.
124
125=head1 NOTES
126
127A string without a scheme prefix (that is, a non-URI string) is
128implicitly interpreted as using the F<file:> scheme.
129
130There are some tools that can be used together with
131OSSL_STORE_open() to determine if any failure is caused by an unparsable
132URI, or if it's a different error (such as memory allocation
133failures); if the URI was parsable but the scheme unregistered, the
134top error will have the reason C<OSSL_STORE_R_UNREGISTERED_SCHEME>.
135
136These functions make no direct assumption regarding the pass phrase received
137from the password callback.
138The loaders may make assumptions, however.
139For example, the B<file:> scheme loader inherits the assumptions made by
140OpenSSL functionality that handles the different file types; this is mostly
141relevant for PKCS#12 objects.
142See L<passphrase-encoding(7)> for further information.
143
144=head1 RETURN VALUES
145
146OSSL_STORE_open() returns a pointer to a B<OSSL_STORE_CTX> on success, or
147NULL on failure.
148
149OSSL_STORE_load() returns a pointer to a B<OSSL_STORE_INFO> on success, or NULL
150on error or when end of data is reached.
151Use OSSL_STORE_error() and OSSL_STORE_eof() to determine the meaning of a
152returned NULL.
153
154OSSL_STORE_eof() returns 1 if the end of data has been reached
155or an error occurred, 0 otherwise.
156
157OSSL_STORE_error() returns 1 if an error occurred in an OSSL_STORE_load() call,
158otherwise 0.
159
160OSSL_STORE_delete(), OSSL_STORE_ctrl() and OSSL_STORE_close() return 1 on
161success, or 0 on failure.
162
163=head1 SEE ALSO
164
165L<ossl_store(7)>, L<OSSL_STORE_INFO(3)>, L<OSSL_STORE_register_loader(3)>,
166L<passphrase-encoding(7)>
167
168=head1 HISTORY
169
170OSSL_STORE_delete() was added in OpenSSL 3.2.
171
172OSSL_STORE_open_ex() was added in OpenSSL 3.0.
173
174B<OSSL_STORE_CTX>, OSSL_STORE_post_process_info_fn(), OSSL_STORE_open(),
175OSSL_STORE_ctrl(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close()
176were added in OpenSSL 1.1.1.
177
178Handling of NULL I<ctx> argument for OSSL_STORE_close()
179was introduced in OpenSSL 1.1.1h.
180
181OSSL_STORE_ctrl() and OSSL_STORE_vctrl() were deprecated in OpenSSL 3.0.
182
183=head1 COPYRIGHT
184
185Copyright 2016-2023 The OpenSSL Project Authors. All Rights Reserved.
186
187Licensed under the Apache License 2.0 (the "License").  You may not use
188this file except in compliance with the License.  You can obtain a copy
189in the file LICENSE in the source distribution or at
190L<https://www.openssl.org/source/license.html>.
191
192=cut
193