1=pod 2 3=head1 NAME 4 5OSSL_STORE_CTX, OSSL_STORE_post_process_info_fn, OSSL_STORE_open, 6OSSL_STORE_ctrl, OSSL_STORE_load, OSSL_STORE_eof, OSSL_STORE_error, 7OSSL_STORE_close - Types and functions to read objects from a URI 8 9=head1 SYNOPSIS 10 11 #include <openssl/store.h> 12 13 typedef struct ossl_store_ctx_st OSSL_STORE_CTX; 14 15 typedef OSSL_STORE_INFO *(*OSSL_STORE_post_process_info_fn)(OSSL_STORE_INFO *, 16 void *); 17 18 OSSL_STORE_CTX *OSSL_STORE_open(const char *uri, const UI_METHOD *ui_method, 19 void *ui_data, 20 OSSL_STORE_post_process_info_fn post_process, 21 void *post_process_data); 22 int OSSL_STORE_ctrl(OSSL_STORE_CTX *ctx, int cmd, ... /* args */); 23 OSSL_STORE_INFO *OSSL_STORE_load(OSSL_STORE_CTX *ctx); 24 int OSSL_STORE_eof(OSSL_STORE_CTX *ctx); 25 int OSSL_STORE_error(OSSL_STORE_CTX *ctx); 26 int OSSL_STORE_close(OSSL_STORE_CTX *ctx); 27 28=head1 DESCRIPTION 29 30These functions help the application to fetch supported objects (see 31L<OSSL_STORE_INFO(3)/SUPPORTED OBJECTS> for information on which those are) 32from a given URI (see L</SUPPORTED SCHEMES> for more information on 33the supported URI schemes). 34The general method to do so is to "open" the URI using OSSL_STORE_open(), 35read each available and supported object using OSSL_STORE_load() as long as 36OSSL_STORE_eof() hasn't been reached, and finish it off with OSSL_STORE_close(). 37 38The retrieved information is stored in a B<OSSL_STORE_INFO>, which is further 39described in L<OSSL_STORE_INFO(3)>. 40 41=head2 Types 42 43B<OSSL_STORE_CTX> is a context variable that holds all the internal 44information for OSSL_STORE_open(), OSSL_STORE_load(), OSSL_STORE_eof() and 45OSSL_STORE_close() to work together. 46 47=head2 Functions 48 49OSSL_STORE_open() takes a uri or path I<uri>, password UI method 50I<ui_method> with associated data I<ui_data>, and post processing 51callback I<post_process> with associated data I<post_process_data>, 52opens a channel to the data located at that URI and returns a 53B<OSSL_STORE_CTX> with all necessary internal information. 54The given I<ui_method> and I<ui_data> will be reused by all 55functions that use B<OSSL_STORE_CTX> when interaction is needed, 56for instance to provide a password. 57The given I<post_process> and I<post_process_data> will be reused by 58OSSL_STORE_load() to manipulate or drop the value to be returned. 59The I<post_process> function drops values by returning NULL, which 60will cause OSSL_STORE_load() to start its process over with loading 61the next object, until I<post_process> returns something other than 62NULL, or the end of data is reached as indicated by OSSL_STORE_eof(). 63 64OSSL_STORE_ctrl() takes a B<OSSL_STORE_CTX>, and command number I<cmd> and 65more arguments not specified here. 66The available loader specific command numbers and arguments they each 67take depends on the loader that's used and is documented together with 68that loader. 69 70There are also global controls available: 71 72=over 4 73 74=item B<OSSL_STORE_C_USE_SECMEM> 75 76Controls if the loader should attempt to use secure memory for any 77allocated B<OSSL_STORE_INFO> and its contents. 78This control expects one argument, a pointer to an B<int> that is expected to 79have the value 1 (yes) or 0 (no). 80Any other value is an error. 81 82=back 83 84OSSL_STORE_load() takes a B<OSSL_STORE_CTX>, tries to load the next available 85object and return it wrapped with B<OSSL_STORE_INFO>. 86 87OSSL_STORE_eof() takes a B<OSSL_STORE_CTX> and checks if we've reached the end 88of data. 89 90OSSL_STORE_error() takes a B<OSSL_STORE_CTX> and checks if an error occurred in 91the last OSSL_STORE_load() call. 92Note that it may still be meaningful to try and load more objects, unless 93OSSL_STORE_eof() shows that the end of data has been reached. 94 95OSSL_STORE_close() takes a B<OSSL_STORE_CTX>, closes the channel that was opened 96by OSSL_STORE_open() and frees all other information that was stored in the 97B<OSSL_STORE_CTX>, as well as the B<OSSL_STORE_CTX> itself. 98If I<ctx> is NULL it does nothing. 99 100=head1 SUPPORTED SCHEMES 101 102The basic supported scheme is B<file:>. 103Any other scheme can be added dynamically, using 104OSSL_STORE_register_loader(). 105 106=head1 NOTES 107 108A string without a scheme prefix (that is, a non-URI string) is 109implicitly interpreted as using the F<file:> scheme. 110 111There are some tools that can be used together with 112OSSL_STORE_open() to determine if any failure is caused by an unparsable 113URI, or if it's a different error (such as memory allocation 114failures); if the URI was parsable but the scheme unregistered, the 115top error will have the reason C<OSSL_STORE_R_UNREGISTERED_SCHEME>. 116 117These functions make no direct assumption regarding the pass phrase received 118from the password callback. 119The loaders may make assumptions, however. 120For example, the B<file:> scheme loader inherits the assumptions made by 121OpenSSL functionality that handles the different file types; this is mostly 122relevant for PKCS#12 objects. 123See L<passphrase-encoding(7)> for further information. 124 125=head1 RETURN VALUES 126 127OSSL_STORE_open() returns a pointer to a B<OSSL_STORE_CTX> on success, or 128NULL on failure. 129 130OSSL_STORE_load() returns a pointer to a B<OSSL_STORE_INFO> on success, or 131NULL on error or when end of data is reached. 132Use OSSL_STORE_error() and OSSL_STORE_eof() to determine the meaning of a 133returned NULL. 134 135OSSL_STORE_eof() returns 1 if the end of data has been reached, otherwise 1360. 137 138OSSL_STORE_error() returns 1 if an error occurred in an OSSL_STORE_load() call, 139otherwise 0. 140 141OSSL_STORE_ctrl() and OSSL_STORE_close() returns 1 on success, or 0 on failure. 142 143=head1 SEE ALSO 144 145L<ossl_store(7)>, L<OSSL_STORE_INFO(3)>, L<OSSL_STORE_register_loader(3)>, 146L<passphrase-encoding(7)> 147 148=head1 HISTORY 149 150OSSL_STORE_CTX(), OSSL_STORE_post_process_info_fn(), OSSL_STORE_open(), 151OSSL_STORE_ctrl(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close() 152were added in OpenSSL 1.1.1. 153 154Handling of NULL I<ctx> argument for OSSL_STORE_close() 155was introduced in OpenSSL 1.1.1h. 156 157=head1 COPYRIGHT 158 159Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved. 160 161Licensed under the OpenSSL license (the "License"). You may not use 162this file except in compliance with the License. You can obtain a copy 163in the file LICENSE in the source distribution or at 164L<https://www.openssl.org/source/license.html>. 165 166=cut 167