1=pod
2
3=head1 NAME
4
5OBJ_nid2obj, OBJ_nid2ln, OBJ_nid2sn, OBJ_obj2nid, OBJ_txt2nid, OBJ_ln2nid, OBJ_sn2nid,
6OBJ_cmp, OBJ_dup, OBJ_txt2obj, OBJ_obj2txt, OBJ_create, OBJ_cleanup - ASN1 object utility
7functions
8
9=head1 SYNOPSIS
10
11 #include <openssl/objects.h>
12
13 ASN1_OBJECT * OBJ_nid2obj(int n);
14 const char *  OBJ_nid2ln(int n);
15 const char *  OBJ_nid2sn(int n);
16
17 int OBJ_obj2nid(const ASN1_OBJECT *o);
18 int OBJ_ln2nid(const char *ln);
19 int OBJ_sn2nid(const char *sn);
20
21 int OBJ_txt2nid(const char *s);
22
23 ASN1_OBJECT * OBJ_txt2obj(const char *s, int no_name);
24 int OBJ_obj2txt(char *buf, int buf_len, const ASN1_OBJECT *a, int no_name);
25
26 int OBJ_cmp(const ASN1_OBJECT *a,const ASN1_OBJECT *b);
27 ASN1_OBJECT * OBJ_dup(const ASN1_OBJECT *o);
28
29 int OBJ_create(const char *oid,const char *sn,const char *ln);
30 void OBJ_cleanup(void);
31
32=head1 DESCRIPTION
33
34The ASN1 object utility functions process ASN1_OBJECT structures which are
35a representation of the ASN1 OBJECT IDENTIFIER (OID) type.
36
37OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID B<n> to
38an ASN1_OBJECT structure, its long name and its short name respectively,
39or B<NULL> is an error occurred.
40
41OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding NID
42for the object B<o>, the long name <ln> or the short name <sn> respectively
43or NID_undef if an error occurred.
44
45OBJ_txt2nid() returns NID corresponding to text string <s>. B<s> can be
46a long name, a short name or the numerical respresentation of an object.
47
48OBJ_txt2obj() converts the text string B<s> into an ASN1_OBJECT structure.
49If B<no_name> is 0 then long names and short names will be interpreted
50as well as numerical forms. If B<no_name> is 1 only the numerical form
51is acceptable.
52
53OBJ_obj2txt() converts the B<ASN1_OBJECT> B<a> into a textual representation.
54The representation is written as a null terminated string to B<buf>
55at most B<buf_len> bytes are written, truncating the result if necessary.
56The total amount of space required is returned. If B<no_name> is 0 then
57if the object has a long or short name then that will be used, otherwise
58the numerical form will be used. If B<no_name> is 1 then the numerical
59form will always be used.
60
61OBJ_cmp() compares B<a> to B<b>. If the two are identical 0 is returned.
62
63OBJ_dup() returns a copy of B<o>.
64
65OBJ_create() adds a new object to the internal table. B<oid> is the
66numerical form of the object, B<sn> the short name and B<ln> the
67long name. A new NID is returned for the created object.
68
69OBJ_cleanup() cleans up OpenSSLs internal object table: this should
70be called before an application exits if any new objects were added
71using OBJ_create().
72
73=head1 NOTES
74
75Objects in OpenSSL can have a short name, a long name and a numerical
76identifier (NID) associated with them. A standard set of objects is
77represented in an internal table. The appropriate values are defined
78in the header file B<objects.h>.
79
80For example the OID for commonName has the following definitions:
81
82 #define SN_commonName                   "CN"
83 #define LN_commonName                   "commonName"
84 #define NID_commonName                  13
85
86New objects can be added by calling OBJ_create().
87
88Table objects have certain advantages over other objects: for example
89their NIDs can be used in a C language switch statement. They are
90also static constant structures which are shared: that is there
91is only a single constant structure for each table object.
92
93Objects which are not in the table have the NID value NID_undef.
94
95Objects do not need to be in the internal tables to be processed,
96the functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical
97form of an OID.
98
99=head1 EXAMPLES
100
101Create an object for B<commonName>:
102
103 ASN1_OBJECT *o;
104 o = OBJ_nid2obj(NID_commonName);
105
106Check if an object is B<commonName>
107
108 if (OBJ_obj2nid(obj) == NID_commonName)
109	/* Do something */
110
111Create a new NID and initialize an object from it:
112
113 int new_nid;
114 ASN1_OBJECT *obj;
115 new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
116
117 obj = OBJ_nid2obj(new_nid);
118
119Create a new object directly:
120
121 obj = OBJ_txt2obj("1.2.3.4", 1);
122
123=head1 BUGS
124
125OBJ_obj2txt() is awkward and messy to use: it doesn't follow the
126convention of other OpenSSL functions where the buffer can be set
127to B<NULL> to determine the amount of data that should be written.
128Instead B<buf> must point to a valid buffer and B<buf_len> should
129be set to a positive value. A buffer length of 80 should be more
130than enough to handle any OID encountered in practice.
131
132=head1 RETURN VALUES
133
134OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an
135error occurred.
136
137OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL>
138on error.
139
140OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return
141a NID or B<NID_undef> on error.
142
143=head1 SEE ALSO
144
145L<ERR_get_error(3)|ERR_get_error(3)>
146
147=head1 HISTORY
148
149TBA
150
151=cut
152