1=pod 2 3=head1 NAME 4 5OSSL_ENCODER_CTX, 6OSSL_ENCODER_CTX_new, 7OSSL_ENCODER_settable_ctx_params, 8OSSL_ENCODER_CTX_set_params, 9OSSL_ENCODER_CTX_free, 10OSSL_ENCODER_CTX_set_selection, 11OSSL_ENCODER_CTX_set_output_type, 12OSSL_ENCODER_CTX_set_output_structure, 13OSSL_ENCODER_CTX_add_encoder, 14OSSL_ENCODER_CTX_add_extra, 15OSSL_ENCODER_CTX_get_num_encoders, 16OSSL_ENCODER_INSTANCE, 17OSSL_ENCODER_INSTANCE_get_encoder, 18OSSL_ENCODER_INSTANCE_get_encoder_ctx, 19OSSL_ENCODER_INSTANCE_get_output_type, 20OSSL_ENCODER_INSTANCE_get_output_structure, 21OSSL_ENCODER_CONSTRUCT, 22OSSL_ENCODER_CLEANUP, 23OSSL_ENCODER_CTX_set_construct, 24OSSL_ENCODER_CTX_set_construct_data, 25OSSL_ENCODER_CTX_set_cleanup 26- Encoder context routines 27 28=head1 SYNOPSIS 29 30 #include <openssl/encoder.h> 31 32 typedef struct ossl_encoder_ctx_st OSSL_ENCODER_CTX; 33 34 OSSL_ENCODER_CTX *OSSL_ENCODER_CTX_new(); 35 const OSSL_PARAM *OSSL_ENCODER_settable_ctx_params(OSSL_ENCODER *encoder); 36 int OSSL_ENCODER_CTX_set_params(OSSL_ENCODER_CTX *ctx, 37 const OSSL_PARAM params[]); 38 void OSSL_ENCODER_CTX_free(OSSL_ENCODER_CTX *ctx); 39 40 int OSSL_ENCODER_CTX_set_selection(OSSL_ENCODER_CTX *ctx, int selection); 41 int OSSL_ENCODER_CTX_set_output_type(OSSL_ENCODER_CTX *ctx, 42 const char *output_type); 43 int OSSL_ENCODER_CTX_set_output_structure(OSSL_ENCODER_CTX *ctx, 44 const char *output_structure); 45 46 int OSSL_ENCODER_CTX_add_encoder(OSSL_ENCODER_CTX *ctx, OSSL_ENCODER *encoder); 47 int OSSL_ENCODER_CTX_add_extra(OSSL_ENCODER_CTX *ctx, 48 OSSL_LIB_CTX *libctx, const char *propq); 49 int OSSL_ENCODER_CTX_get_num_encoders(OSSL_ENCODER_CTX *ctx); 50 51 typedef struct ossl_encoder_instance_st OSSL_ENCODER_INSTANCE; 52 OSSL_ENCODER * 53 OSSL_ENCODER_INSTANCE_get_encoder(OSSL_ENCODER_INSTANCE *encoder_inst); 54 void * 55 OSSL_ENCODER_INSTANCE_get_encoder_ctx(OSSL_ENCODER_INSTANCE *encoder_inst); 56 const char * 57 OSSL_ENCODER_INSTANCE_get_output_type(OSSL_ENCODER_INSTANCE *encoder_inst); 58 const char * 59 OSSL_ENCODER_INSTANCE_get_output_structure(OSSL_ENCODER_INSTANCE *encoder_inst); 60 61 typedef const void *OSSL_ENCODER_CONSTRUCT(OSSL_ENCODER_INSTANCE *encoder_inst, 62 void *construct_data); 63 typedef void OSSL_ENCODER_CLEANUP(void *construct_data); 64 65 int OSSL_ENCODER_CTX_set_construct(OSSL_ENCODER_CTX *ctx, 66 OSSL_ENCODER_CONSTRUCT *construct); 67 int OSSL_ENCODER_CTX_set_construct_data(OSSL_ENCODER_CTX *ctx, 68 void *construct_data); 69 int OSSL_ENCODER_CTX_set_cleanup(OSSL_ENCODER_CTX *ctx, 70 OSSL_ENCODER_CLEANUP *cleanup); 71 72=head1 DESCRIPTION 73 74Encoding an input object to the desired encoding may be done with a chain of 75encoder implementations, which means that the output from one encoder may be 76the input for the next in the chain. The B<OSSL_ENCODER_CTX> holds all the 77data about these encoders. This allows having generic format encoders such 78as DER to PEM, as well as more specialized encoders like RSA to DER. 79 80The final output type must be given, and a chain of encoders must end with 81an implementation that produces that output type. 82 83At the beginning of the encoding process, a constructor provided by the 84caller is called to ensure that there is an appropriate provider-side object 85to start with. 86The constructor is set with OSSL_ENCODER_CTX_set_construct(). 87 88B<OSSL_ENCODER_INSTANCE> is an opaque structure that contains data about the 89encoder that is going to be used, and that may be useful for the 90constructor. There are some functions to extract data from this type, 91described in L</Constructor> below. 92 93=head2 Functions 94 95OSSL_ENCODER_CTX_new() creates a B<OSSL_ENCODER_CTX>. 96 97OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)> 98array of parameter descriptors. 99 100OSSL_ENCODER_CTX_set_params() attempts to set parameters specified 101with an L<OSSL_PARAM(3)> array I<params>. Parameters that the 102implementation doesn't recognise should be ignored. 103 104OSSL_ENCODER_CTX_free() frees the given context I<ctx>. 105 106OSSL_ENCODER_CTX_add_encoder() populates the B<OSSL_ENCODER_CTX> 107I<ctx> with a encoder, to be used to encode an input object. 108 109OSSL_ENCODER_CTX_add_extra() finds encoders that further encodes output 110from already added encoders, and adds them as well. This is used to build 111encoder chains. 112 113OSSL_ENCODER_CTX_set_output_type() sets the ending output type. This must 114be specified, and determines if a complete encoder chain is available. 115 116OSSL_ENCODER_CTX_set_output_structure() sets the desired output structure. 117This may be used to determines what encoder implementations may be used. 118Depending on the type of object being encoded, the output structure may 119not be relevant. 120 121OSSL_ENCODER_CTX_get_num_encoders() gets the number of encoders currently 122added to the context I<ctx>. 123 124OSSL_ENCODER_CTX_set_construct() sets the constructor I<construct>. 125 126OSSL_ENCODER_CTX_set_construct_data() sets the constructor data that is 127passed to the constructor every time it's called. 128 129OSSL_ENCODER_CTX_set_cleanup() sets the constructor data I<cleanup> 130function. This is called by L<OSSL_ENCODER_CTX_free(3)>. 131 132=head2 Constructor 133 134A B<OSSL_ENCODER_CONSTRUCT> gets the following arguments: 135 136=over 4 137 138=item I<encoder_inst> 139 140The B<OSSL_ENCODER_INSTANCE> for the encoder from which the constructor gets 141its data. 142 143=item I<construct_data> 144 145The pointer that was set with OSSL_ENCODE_CTX_set_construct_data(). 146 147=back 148 149The constructor is expected to return a valid (non-NULL) pointer to a 150provider-native object that can be used as first input of an encoding chain, 151or NULL to indicate that an error has occurred. 152 153These utility functions may be used by a constructor: 154 155OSSL_ENCODER_INSTANCE_get_encoder() can be used to get the encoder 156implementation of the encoder instance I<encoder_inst>. 157 158OSSL_ENCODER_INSTANCE_get_encoder_ctx() can be used to get the encoder 159implementation's provider context of the encoder instance I<encoder_inst>. 160 161OSSL_ENCODER_INSTANCE_get_output_type() can be used to get the output type 162for the encoder implementation of the encoder instance I<encoder_inst>. 163This will never be NULL. 164 165OSSL_ENCODER_INSTANCE_get_output_structure() can be used to get the output 166structure for the encoder implementation of the encoder instance 167I<encoder_inst>. 168This may be NULL. 169 170=head1 RETURN VALUES 171 172OSSL_ENCODER_CTX_new() returns a pointer to a B<OSSL_ENCODER_CTX>, or NULL 173if the context structure couldn't be allocated. 174 175OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)> array, or 176NULL if none is available. 177 178OSSL_ENCODER_CTX_set_params() returns 1 if all recognised parameters were 179valid, or 0 if one of them was invalid or caused some other failure in the 180implementation. 181 182OSSL_ENCODER_CTX_add_encoder(), OSSL_ENCODER_CTX_add_extra(), 183OSSL_ENCODER_CTX_set_construct(), OSSL_ENCODER_CTX_set_construct_data() and 184OSSL_ENCODER_CTX_set_cleanup() return 1 on success, or 0 on failure. 185 186OSSL_ENCODER_CTX_get_num_encoders() returns the current number of encoders. 187It returns 0 if I<ctx> is NULL. 188 189OSSL_ENCODER_INSTANCE_get_encoder() returns an B<OSSL_ENCODER> pointer on 190success, or NULL on failure. 191 192OSSL_ENCODER_INSTANCE_get_encoder_ctx() returns a provider context pointer on 193success, or NULL on failure. 194 195OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the 196input type, if relevant. NULL is a valid returned value. 197 198OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the 199output type. 200 201OSSL_ENCODER_INSTANCE_get_output_structure() returns a string with the name 202of the output structure. 203 204=head1 SEE ALSO 205 206L<provider(7)>, L<OSSL_ENCODER(3)> 207 208=head1 HISTORY 209 210The functions described here were added in OpenSSL 3.0. 211 212=head1 COPYRIGHT 213 214Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved. 215 216Licensed under the Apache License 2.0 (the "License"). You may not use 217this file except in compliance with the License. You can obtain a copy 218in the file LICENSE in the source distribution or at 219L<https://www.openssl.org/source/license.html>. 220 221=cut 222