OSSL_DECODER.pod 6.4 KB

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  1. =pod
  2. =head1 NAME
  3. OSSL_DECODER,
  4. OSSL_DECODER_fetch,
  5. OSSL_DECODER_up_ref,
  6. OSSL_DECODER_free,
  7. OSSL_DECODER_get0_provider,
  8. OSSL_DECODER_get0_properties,
  9. OSSL_DECODER_is_a,
  10. OSSL_DECODER_get0_name,
  11. OSSL_DECODER_get0_description,
  12. OSSL_DECODER_do_all_provided,
  13. OSSL_DECODER_names_do_all,
  14. OSSL_DECODER_gettable_params,
  15. OSSL_DECODER_get_params
  16. - Decoder method routines
  17. =head1 SYNOPSIS
  18. #include <openssl/decoder.h>
  19. typedef struct ossl_decoder_st OSSL_DECODER;
  20. OSSL_DECODER *OSSL_DECODER_fetch(OSSL_LIB_CTX *ctx, const char *name,
  21. const char *properties);
  22. int OSSL_DECODER_up_ref(OSSL_DECODER *decoder);
  23. void OSSL_DECODER_free(OSSL_DECODER *decoder);
  24. const OSSL_PROVIDER *OSSL_DECODER_get0_provider(const OSSL_DECODER *decoder);
  25. const char *OSSL_DECODER_get0_properties(const OSSL_DECODER *decoder);
  26. int OSSL_DECODER_is_a(const OSSL_DECODER *decoder, const char *name);
  27. const char *OSSL_DECODER_get0_name(const OSSL_DECODER *decoder);
  28. const char *OSSL_DECODER_get0_description(const OSSL_DECODER *decoder);
  29. void OSSL_DECODER_do_all_provided(OSSL_LIB_CTX *libctx,
  30. void (*fn)(OSSL_DECODER *decoder, void *arg),
  31. void *arg);
  32. int OSSL_DECODER_names_do_all(const OSSL_DECODER *decoder,
  33. void (*fn)(const char *name, void *data),
  34. void *data);
  35. const OSSL_PARAM *OSSL_DECODER_gettable_params(OSSL_DECODER *decoder);
  36. int OSSL_DECODER_get_params(OSSL_DECODER_CTX *ctx, const OSSL_PARAM params[]);
  37. =head1 DESCRIPTION
  38. B<OSSL_DECODER> is a method for decoders, which know how to
  39. decode encoded data into an object of some type that the rest
  40. of OpenSSL knows how to handle.
  41. OSSL_DECODER_fetch() looks for an algorithm within the provider that
  42. has been loaded into the B<OSSL_LIB_CTX> given by I<ctx>, having the
  43. name given by I<name> and the properties given by I<properties>.
  44. The I<name> determines what type of object the fetched decoder
  45. method is expected to be able to decode, and the properties are
  46. used to determine the expected output type.
  47. For known properties and the values they may have, please have a look
  48. in L<provider-encoder(7)/Names and properties>.
  49. OSSL_DECODER_up_ref() increments the reference count for the given
  50. I<decoder>.
  51. OSSL_DECODER_free() decrements the reference count for the given
  52. I<decoder>, and when the count reaches zero, frees it.
  53. OSSL_DECODER_get0_provider() returns the provider of the given
  54. I<decoder>.
  55. OSSL_DECODER_get0_properties() returns the property definition associated
  56. with the given I<decoder>.
  57. OSSL_DECODER_is_a() checks if I<decoder> is an implementation
  58. of an algorithm that's identifiable with I<name>.
  59. OSSL_DECODER_get0_name() returns the name used to fetch the given I<decoder>.
  60. OSSL_DECODER_get0_description() returns a description of the I<decoder>, meant
  61. for display and human consumption. The description is at the discretion
  62. of the I<decoder> implementation.
  63. OSSL_DECODER_names_do_all() traverses all names for the given
  64. I<decoder>, and calls I<fn> with each name and I<data> as arguments.
  65. OSSL_DECODER_do_all_provided() traverses all decoder
  66. implementations by all activated providers in the library context
  67. I<libctx>, and for each of the implementations, calls I<fn> with the
  68. implementation method and I<arg> as arguments.
  69. OSSL_DECODER_gettable_params() returns an L<OSSL_PARAM(3)>
  70. array of parameter descriptors.
  71. OSSL_DECODER_get_params() attempts to get parameters specified
  72. with an L<OSSL_PARAM(3)> array I<params>. Parameters that the
  73. implementation doesn't recognise should be ignored.
  74. =head1 RETURN VALUES
  75. OSSL_DECODER_fetch() returns a pointer to an OSSL_DECODER object,
  76. or NULL on error.
  77. OSSL_DECODER_up_ref() returns 1 on success, or 0 on error.
  78. OSSL_DECODER_free() doesn't return any value.
  79. OSSL_DECODER_get0_provider() returns a pointer to a provider object, or
  80. NULL on error.
  81. OSSL_DECODER_get0_properties() returns a pointer to a property
  82. definition string, or NULL on error.
  83. OSSL_DECODER_is_a() returns 1 if I<decoder> was identifiable,
  84. otherwise 0.
  85. OSSL_DECODER_get0_name() returns the algorithm name from the provided
  86. implementation for the given I<decoder>. Note that the I<decoder> may have
  87. multiple synonyms associated with it. In this case the first name from the
  88. algorithm definition is returned. Ownership of the returned string is retained
  89. by the I<decoder> object and should not be freed by the caller.
  90. OSSL_DECODER_get0_description() returns a pointer to a description, or NULL if
  91. there isn't one.
  92. OSSL_DECODER_names_do_all() returns 1 if the callback was called for all
  93. names. A return value of 0 means that the callback was not called for any names.
  94. =head1 NOTES
  95. OSSL_DECODER_fetch() may be called implicitly by other fetching
  96. functions, using the same library context and properties.
  97. Any other API that uses keys will typically do this.
  98. =head1 EXAMPLES
  99. To list all decoders in a provider to a bio_out:
  100. static void collect_decoders(OSSL_DECODER *decoder, void *stack)
  101. {
  102. STACK_OF(OSSL_DECODER) *decoder_stack = stack;
  103. sk_OSSL_DECODER_push(decoder_stack, decoder);
  104. OSSL_DECODER_up_ref(decoder);
  105. }
  106. void print_name(const char *name, void *vdata)
  107. {
  108. BIO *bio = vdata;
  109. BIO_printf(bio, "%s ", name);
  110. }
  111. STACK_OF(OSSL_DECODER) *decoders;
  112. int i;
  113. decoders = sk_OSSL_DECODER_new_null();
  114. BIO_printf(bio_out, "DECODERs provided by %s:\n", provider);
  115. OSSL_DECODER_do_all_provided(NULL, collect_decoders,
  116. decoders);
  117. for (i = 0; i < sk_OSSL_DECODER_num(decoders); i++) {
  118. OSSL_DECODER *decoder = sk_OSSL_DECODER_value(decoders, i);
  119. if (strcmp(OSSL_PROVIDER_get0_name(OSSL_DECODER_get0_provider(decoder)),
  120. provider) != 0)
  121. continue;
  122. if (OSSL_DECODER_names_do_all(decoder, print_name, bio_out))
  123. BIO_printf(bio_out, "\n");
  124. }
  125. sk_OSSL_DECODER_pop_free(decoders, OSSL_DECODER_free);
  126. =head1 SEE ALSO
  127. L<provider(7)>, L<OSSL_DECODER_CTX(3)>, L<OSSL_DECODER_from_bio(3)>,
  128. L<OSSL_DECODER_CTX_new_for_pkey(3)>, L<OSSL_LIB_CTX(3)>
  129. =head1 HISTORY
  130. The functions described here were added in OpenSSL 3.0.
  131. =head1 COPYRIGHT
  132. Copyright 2020-2022 The OpenSSL Project Authors. All Rights Reserved.
  133. Licensed under the Apache License 2.0 (the "License"). You may not use
  134. this file except in compliance with the License. You can obtain a copy
  135. in the file LICENSE in the source distribution or at
  136. L<https://www.openssl.org/source/license.html>.
  137. =cut