OBJ_nid2obj.pod 6.7 KB

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  1. =pod
  2. =head1 NAME
  3. i2t_ASN1_OBJECT,
  4. OBJ_length, OBJ_get0_data, OBJ_nid2obj, OBJ_nid2ln,
  5. OBJ_nid2sn, OBJ_obj2nid, OBJ_txt2nid, OBJ_ln2nid, OBJ_sn2nid, OBJ_cmp,
  6. OBJ_dup, OBJ_txt2obj, OBJ_obj2txt, OBJ_create, OBJ_cleanup
  7. - ASN1 object utility functions
  8. =head1 SYNOPSIS
  9. #include <openssl/objects.h>
  10. ASN1_OBJECT *OBJ_nid2obj(int n);
  11. const char *OBJ_nid2ln(int n);
  12. const char *OBJ_nid2sn(int n);
  13. int OBJ_obj2nid(const ASN1_OBJECT *o);
  14. int OBJ_ln2nid(const char *ln);
  15. int OBJ_sn2nid(const char *sn);
  16. int OBJ_txt2nid(const char *s);
  17. ASN1_OBJECT *OBJ_txt2obj(const char *s, int no_name);
  18. int OBJ_obj2txt(char *buf, int buf_len, const ASN1_OBJECT *a, int no_name);
  19. int i2t_ASN1_OBJECT(char *buf, int buf_len, const ASN1_OBJECT *a);
  20. int OBJ_cmp(const ASN1_OBJECT *a, const ASN1_OBJECT *b);
  21. ASN1_OBJECT *OBJ_dup(const ASN1_OBJECT *o);
  22. int OBJ_create(const char *oid, const char *sn, const char *ln);
  23. size_t OBJ_length(const ASN1_OBJECT *obj);
  24. const unsigned char *OBJ_get0_data(const ASN1_OBJECT *obj);
  25. Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining
  26. B<OPENSSL_API_COMPAT> with a suitable version value, see
  27. L<openssl_user_macros(7)>:
  28. void OBJ_cleanup(void);
  29. =head1 DESCRIPTION
  30. The ASN1 object utility functions process ASN1_OBJECT structures which are
  31. a representation of the ASN1 OBJECT IDENTIFIER (OID) type.
  32. For convenience, OIDs are usually represented in source code as numeric
  33. identifiers, or B<NID>s. OpenSSL has an internal table of OIDs that
  34. are generated when the library is built, and their corresponding NIDs
  35. are available as defined constants. For the functions below, application
  36. code should treat all returned values -- OIDs, NIDs, or names -- as
  37. constants.
  38. OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID B<n> to
  39. an ASN1_OBJECT structure, its long name and its short name respectively,
  40. or B<NULL> if an error occurred.
  41. OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding NID
  42. for the object B<o>, the long name <ln> or the short name <sn> respectively
  43. or NID_undef if an error occurred.
  44. OBJ_txt2nid() returns NID corresponding to text string <s>. B<s> can be
  45. a long name, a short name or the numerical representation of an object.
  46. OBJ_txt2obj() converts the text string B<s> into an ASN1_OBJECT structure.
  47. If B<no_name> is 0 then long names and short names will be interpreted
  48. as well as numerical forms. If B<no_name> is 1 only the numerical form
  49. is acceptable.
  50. OBJ_obj2txt() converts the B<ASN1_OBJECT> B<a> into a textual representation.
  51. The representation is written as a null terminated string to B<buf>
  52. at most B<buf_len> bytes are written, truncating the result if necessary.
  53. The total amount of space required is returned. If B<no_name> is 0 then
  54. if the object has a long or short name then that will be used, otherwise
  55. the numerical form will be used. If B<no_name> is 1 then the numerical
  56. form will always be used.
  57. i2t_ASN1_OBJECT() is the same as OBJ_obj2txt() with the B<no_name> set to zero.
  58. OBJ_cmp() compares B<a> to B<b>. If the two are identical 0 is returned.
  59. OBJ_dup() returns a copy of B<o>.
  60. OBJ_create() adds a new object to the internal table. B<oid> is the
  61. numerical form of the object, B<sn> the short name and B<ln> the
  62. long name. A new NID is returned for the created object in case of
  63. success and NID_undef in case of failure.
  64. OBJ_length() returns the size of the content octets of B<obj>.
  65. OBJ_get0_data() returns a pointer to the content octets of B<obj>.
  66. The returned pointer is an internal pointer which B<must not> be freed.
  67. OBJ_cleanup() releases any resources allocated by creating new objects.
  68. =head1 NOTES
  69. Objects in OpenSSL can have a short name, a long name and a numerical
  70. identifier (NID) associated with them. A standard set of objects is
  71. represented in an internal table. The appropriate values are defined
  72. in the header file B<objects.h>.
  73. For example the OID for commonName has the following definitions:
  74. #define SN_commonName "CN"
  75. #define LN_commonName "commonName"
  76. #define NID_commonName 13
  77. New objects can be added by calling OBJ_create().
  78. Table objects have certain advantages over other objects: for example
  79. their NIDs can be used in a C language switch statement. They are
  80. also static constant structures which are shared: that is there
  81. is only a single constant structure for each table object.
  82. Objects which are not in the table have the NID value NID_undef.
  83. Objects do not need to be in the internal tables to be processed,
  84. the functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical
  85. form of an OID.
  86. Some objects are used to represent algorithms which do not have a
  87. corresponding ASN.1 OBJECT IDENTIFIER encoding (for example no OID currently
  88. exists for a particular algorithm). As a result they B<cannot> be encoded or
  89. decoded as part of ASN.1 structures. Applications can determine if there
  90. is a corresponding OBJECT IDENTIFIER by checking OBJ_length() is not zero.
  91. These functions cannot return B<const> because an B<ASN1_OBJECT> can
  92. represent both an internal, constant, OID and a dynamically-created one.
  93. The latter cannot be constant because it needs to be freed after use.
  94. =head1 RETURN VALUES
  95. OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an
  96. error occurred.
  97. OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL>
  98. on error.
  99. OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return
  100. a NID or B<NID_undef> on error.
  101. =head1 EXAMPLES
  102. Create an object for B<commonName>:
  103. ASN1_OBJECT *o = OBJ_nid2obj(NID_commonName);
  104. Check if an object is B<commonName>
  105. if (OBJ_obj2nid(obj) == NID_commonName)
  106. /* Do something */
  107. Create a new NID and initialize an object from it:
  108. int new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
  109. ASN1_OBJECT *obj = OBJ_nid2obj(new_nid);
  110. Create a new object directly:
  111. obj = OBJ_txt2obj("1.2.3.4", 1);
  112. =head1 BUGS
  113. OBJ_obj2txt() is awkward and messy to use: it doesn't follow the
  114. convention of other OpenSSL functions where the buffer can be set
  115. to B<NULL> to determine the amount of data that should be written.
  116. Instead B<buf> must point to a valid buffer and B<buf_len> should
  117. be set to a positive value. A buffer length of 80 should be more
  118. than enough to handle any OID encountered in practice.
  119. =head1 SEE ALSO
  120. L<ERR_get_error(3)>
  121. =head1 HISTORY
  122. OBJ_cleanup() was deprecated in OpenSSL 1.1.0 by L<OPENSSL_init_crypto(3)>
  123. and should not be used.
  124. =head1 COPYRIGHT
  125. Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.
  126. Licensed under the Apache License 2.0 (the "License"). You may not use
  127. this file except in compliance with the License. You can obtain a copy
  128. in the file LICENSE in the source distribution or at
  129. L<https://www.openssl.org/source/license.html>.
  130. =cut