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 B<uri>, password UI method 50B<ui_method> with associated data B<ui_data>, and post processing 51callback B<post_process> with associated data B<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 B<ui_method> and B<ui_data_data> will be reused by all 55functions that use B<OSSL_STORE_CTX> when interaction is needed. 56The given B<post_process> and B<post_process_data> will be reused by 57OSSL_STORE_load() to manipulate or drop the value to be returned. 58The B<post_process> function drops values by returning B<NULL>, which 59will cause OSSL_STORE_load() to start its process over with loading 60the next object, until B<post_process> returns something other than 61B<NULL>, or the end of data is reached as indicated by OSSL_STORE_eof(). 62 63OSSL_STORE_ctrl() takes a B<OSSL_STORE_CTX>, and command number B<cmd> and 64more arguments not specified here. 65The available loader specific command numbers and arguments they each 66take depends on the loader that's used and is documented together with 67that loader. 68 69There are also global controls available: 70 71=over 4 72 73=item B<OSSL_STORE_C_USE_SECMEM> 74 75Controls if the loader should attempt to use secure memory for any 76allocated B<OSSL_STORE_INFO> and its contents. 77This control expects one argument, a pointer to an B<int> that is expected to 78have the value 1 (yes) or 0 (no). 79Any other value is an error. 80 81=back 82 83OSSL_STORE_load() takes a B<OSSL_STORE_CTX>, tries to load the next available 84object and return it wrapped with B<OSSL_STORE_INFO>. 85 86OSSL_STORE_eof() takes a B<OSSL_STORE_CTX> and checks if we've reached the end 87of data. 88 89OSSL_STORE_error() takes a B<OSSL_STORE_CTX> and checks if an error occurred in 90the last OSSL_STORE_load() call. 91Note that it may still be meaningful to try and load more objects, unless 92OSSL_STORE_eof() shows that the end of data has been reached. 93 94OSSL_STORE_close() takes a B<OSSL_STORE_CTX>, closes the channel that was opened 95by OSSL_STORE_open() and frees all other information that was stored in the 96B<OSSL_STORE_CTX>, as well as the B<OSSL_STORE_CTX> itself. 97 98=head1 SUPPORTED SCHEMES 99 100The basic supported scheme is B<file:>. 101Any other scheme can be added dynamically, using 102OSSL_STORE_register_loader(). 103 104=head1 NOTES 105 106A string without a scheme prefix (that is, a non-URI string) is 107implicitly interpreted as using the F<file:> scheme. 108 109There are some tools that can be used together with 110OSSL_STORE_open() to determine if any failure is caused by an unparsable 111URI, or if it's a different error (such as memory allocation 112failures); if the URI was parsable but the scheme unregistered, the 113top error will have the reason C<OSSL_STORE_R_UNREGISTERED_SCHEME>. 114 115These functions make no direct assumption regarding the pass phrase received 116from the password callback. 117The loaders may make assumptions, however. 118For example, the B<file:> scheme loader inherits the assumptions made by 119OpenSSL functionality that handles the different file types; this is mostly 120relevant for PKCS#12 objects. 121See L<passphrase-encoding(7)> for further information. 122 123=head1 RETURN VALUES 124 125OSSL_STORE_open() returns a pointer to a B<OSSL_STORE_CTX> on success, or 126B<NULL> on failure. 127 128OSSL_STORE_load() returns a pointer to a B<OSSL_STORE_INFO> on success, or 129B<NULL> on error or when end of data is reached. 130Use OSSL_STORE_error() and OSSL_STORE_eof() to determine the meaning of a 131returned B<NULL>. 132 133OSSL_STORE_eof() returns 1 if the end of data has been reached, otherwise 1340. 135 136OSSL_STORE_error() returns 1 if an error occurred in an OSSL_STORE_load() call, 137otherwise 0. 138 139OSSL_STORE_ctrl() and OSSL_STORE_close() returns 1 on success, or 0 on failure. 140 141=head1 SEE ALSO 142 143L<ossl_store(7)>, L<OSSL_STORE_INFO(3)>, L<OSSL_STORE_register_loader(3)>, 144L<passphrase-encoding(7)> 145 146=head1 HISTORY 147 148OSSL_STORE_CTX(), OSSL_STORE_post_process_info_fn(), OSSL_STORE_open(), 149OSSL_STORE_ctrl(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close() 150were added in OpenSSL 1.1.1. 151 152=head1 COPYRIGHT 153 154Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved. 155 156Licensed under the OpenSSL license (the "License"). You may not use 157this file except in compliance with the License. You can obtain a copy 158in the file LICENSE in the source distribution or at 159L<https://www.openssl.org/source/license.html>. 160 161=cut 162