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1=pod
2
3=head1 NAME
4
5i2t_ASN1_OBJECT,
6OBJ_length, OBJ_get0_data, OBJ_nid2obj, OBJ_nid2ln,
7OBJ_nid2sn, OBJ_obj2nid, OBJ_txt2nid, OBJ_ln2nid, OBJ_sn2nid, OBJ_cmp,
8OBJ_dup, OBJ_txt2obj, OBJ_obj2txt, OBJ_create, OBJ_cleanup
9- ASN1 object utility functions
10
11=head1 SYNOPSIS
12
13 #include <openssl/objects.h>
14
15 ASN1_OBJECT *OBJ_nid2obj(int n);
16 const char *OBJ_nid2ln(int n);
17 const char *OBJ_nid2sn(int n);
18
19 int OBJ_obj2nid(const ASN1_OBJECT *o);
20 int OBJ_ln2nid(const char *ln);
21 int OBJ_sn2nid(const char *sn);
22
23 int OBJ_txt2nid(const char *s);
24
25 ASN1_OBJECT *OBJ_txt2obj(const char *s, int no_name);
26 int OBJ_obj2txt(char *buf, int buf_len, const ASN1_OBJECT *a, int no_name);
27
28 int i2t_ASN1_OBJECT(char *buf, int buf_len, const ASN1_OBJECT *a);
29
30 int OBJ_cmp(const ASN1_OBJECT *a, const ASN1_OBJECT *b);
31 ASN1_OBJECT *OBJ_dup(const ASN1_OBJECT *o);
32
33 int OBJ_create(const char *oid, const char *sn, const char *ln);
34
35 size_t OBJ_length(const ASN1_OBJECT *obj);
36 const unsigned char *OBJ_get0_data(const ASN1_OBJECT *obj);
37
38Deprecated:
39
40 #if OPENSSL_API_COMPAT < 0x10100000L
41 void OBJ_cleanup(void)
42 #endif
43
44=head1 DESCRIPTION
45
46The ASN1 object utility functions process ASN1_OBJECT structures which are
47a representation of the ASN1 OBJECT IDENTIFIER (OID) type.
48For convenience, OIDs are usually represented in source code as numeric
49identifiers, or I<NID>s.  OpenSSL has an internal table of OIDs that
50are generated when the library is built, and their corresponding NIDs
51are available as defined constants.  For the functions below, application
52code should treat all returned values -- OIDs, NIDs, or names -- as
53constants.
54
55OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID I<n> to
56an ASN1_OBJECT structure, its long name and its short name respectively,
57or B<NULL> if an error occurred.
58
59OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding NID
60for the object I<o>, the long name <ln> or the short name <sn> respectively
61or NID_undef if an error occurred.
62
63OBJ_txt2nid() returns NID corresponding to text string I<s>. I<s> can be
64a long name, a short name or the numerical representation of an object.
65
66OBJ_txt2obj() converts the text string I<s> into an ASN1_OBJECT structure.
67If I<no_name> is 0 then long names and short names will be interpreted
68as well as numerical forms. If I<no_name> is 1 only the numerical form
69is acceptable.
70
71OBJ_obj2txt() converts the B<ASN1_OBJECT> I<a> into a textual representation.
72Unless I<buf> is NULL,
73the representation is written as a NUL-terminated string to I<buf>, where
74at most I<buf_len> bytes are written, truncating the result if necessary.
75In any case it returns the total string length, excluding the NUL character,
76required for non-truncated representation, or -1 on error.
77If I<no_name> is 0 then if the object has a long or short name
78then that will be used, otherwise the numerical form will be used.
79If I<no_name> is 1 then the numerical form will always be used.
80
81i2t_ASN1_OBJECT() is the same as OBJ_obj2txt() with the I<no_name> set to zero.
82
83OBJ_cmp() compares I<a> to I<b>. If the two are identical 0 is returned.
84
85OBJ_dup() returns a copy of I<o>.
86
87OBJ_create() adds a new object to the internal table. I<oid> is the
88numerical form of the object, I<sn> the short name and I<ln> the
89long name. A new NID is returned for the created object in case of
90success and NID_undef in case of failure.
91
92OBJ_length() returns the size of the content octets of I<obj>.
93
94OBJ_get0_data() returns a pointer to the content octets of I<obj>.
95The returned pointer is an internal pointer which B<must not> be freed.
96
97OBJ_cleanup() releases any resources allocated by creating new objects.
98
99=head1 NOTES
100
101Objects in OpenSSL can have a short name, a long name and a numerical
102identifier (NID) associated with them. A standard set of objects is
103represented in an internal table. The appropriate values are defined
104in the header file B<objects.h>.
105
106For example the OID for commonName has the following definitions:
107
108 #define SN_commonName                   "CN"
109 #define LN_commonName                   "commonName"
110 #define NID_commonName                  13
111
112New objects can be added by calling OBJ_create().
113
114Table objects have certain advantages over other objects: for example
115their NIDs can be used in a C language switch statement. They are
116also static constant structures which are shared: that is there
117is only a single constant structure for each table object.
118
119Objects which are not in the table have the NID value NID_undef.
120
121Objects do not need to be in the internal tables to be processed,
122the functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical
123form of an OID.
124
125Some objects are used to represent algorithms which do not have a
126corresponding ASN.1 OBJECT IDENTIFIER encoding (for example no OID currently
127exists for a particular algorithm). As a result they B<cannot> be encoded or
128decoded as part of ASN.1 structures. Applications can determine if there
129is a corresponding OBJECT IDENTIFIER by checking OBJ_length() is not zero.
130
131These functions cannot return B<const> because an B<ASN1_OBJECT> can
132represent both an internal, constant, OID and a dynamically-created one.
133The latter cannot be constant because it needs to be freed after use.
134
135=head1 RETURN VALUES
136
137OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an
138error occurred.
139
140OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL>
141on error.
142
143OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return
144a NID or B<NID_undef> on error.
145
146OBJ_add_sigid() returns 1 on success or 0 on error.
147
148i2t_ASN1_OBJECT() an OBJ_obj2txt() return -1 on error.
149On success, they return the length of the string written to I<buf> if I<buf> is
150not NULL and I<buf_len> is big enough, otherwise the total string length.
151Note that this does not count the trailing NUL character.
152
153=head1 EXAMPLES
154
155Create an object for B<commonName>:
156
157 ASN1_OBJECT *o = OBJ_nid2obj(NID_commonName);
158
159Check if an object is B<commonName>
160
161 if (OBJ_obj2nid(obj) == NID_commonName)
162     /* Do something */
163
164Create a new NID and initialize an object from it:
165
166 int new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
167 ASN1_OBJECT *obj = OBJ_nid2obj(new_nid);
168
169Create a new object directly:
170
171 obj = OBJ_txt2obj("1.2.3.4", 1);
172
173=head1 SEE ALSO
174
175L<ERR_get_error(3)>
176
177=head1 HISTORY
178
179OBJ_cleanup() was deprecated in OpenSSL 1.1.0 by L<OPENSSL_init_crypto(3)>
180and should not be used.
181
182=head1 COPYRIGHT
183
184Copyright 2002-2022 The OpenSSL Project Authors. All Rights Reserved.
185
186Licensed under the OpenSSL license (the "License").  You may not use
187this file except in compliance with the License.  You can obtain a copy
188in the file LICENSE in the source distribution or at
189L<https://www.openssl.org/source/license.html>.
190
191=cut
192