1OBJ_nid2obj(3) OpenSSL OBJ_nid2obj(3)
2
6 OBJ_nid2obj, OBJ_nid2ln, OBJ_nid2sn, OBJ_obj2nid, OBJ_txt2nid,
7 OBJ_ln2nid, OBJ_sn2nid, OBJ_cmp, OBJ_dup, OBJ_txt2obj, OBJ_obj2txt,
8 OBJ_create, OBJ_cleanup - ASN1 object utility functions
9
11 #include <openssl/objects.h>
12 ASN1_OBJECT * OBJ_nid2obj(int n);
14 const char * OBJ_nid2ln(int n);
15 const char * OBJ_nid2sn(int n);
16 int OBJ_obj2nid(const ASN1_OBJECT *o);
18 int OBJ_ln2nid(const char *ln);
19 int OBJ_sn2nid(const char *sn);
20 int OBJ_txt2nid(const char *s);
22 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 int OBJ_cmp(const ASN1_OBJECT *a,const ASN1_OBJECT *b);
27 ASN1_OBJECT * OBJ_dup(const ASN1_OBJECT *o);
28 int OBJ_create(const char *oid,const char *sn,const char *ln);
30 void OBJ_cleanup(void);
31
33 The ASN1 object utility functions process ASN1_OBJECT structures which
34 are a representation of the ASN1 OBJECT IDENTIFIER (OID) type. For
35 convenience, OIDs are usually represented in source code as numeric
36 identifiers, or NIDs. OpenSSL has an internal table of OIDs that are
37 generated when the library is built, and their corresponding NIDs are
38 available as defined constants. For the functions below, application
39 code should treat all returned values -- OIDs, NIDs, or names -- as
40 constants.
41 OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID n to an
43 ASN1_OBJECT structure, its long name and its short name respectively,
44 or NULL is an error occurred.
45 OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding NID
47 for the object o, the long name <ln> or the short name <sn>
48 respectively or NID_undef if an error occurred.
49 OBJ_txt2nid() returns NID corresponding to text string <s>. s can be a
51 long name, a short name or the numerical respresentation of an object.
52 OBJ_txt2obj() converts the text string s into an ASN1_OBJECT structure.
54 If no_name is 0 then long names and short names will be interpreted as
55 well as numerical forms. If no_name is 1 only the numerical form is
56 acceptable.
57 OBJ_obj2txt() converts the ASN1_OBJECT a into a textual representation.
59 The representation is written as a null terminated string to buf at
60 most buf_len bytes are written, truncating the result if necessary.
61 The total amount of space required is returned. If no_name is 0 then if
62 the object has a long or short name then that will be used, otherwise
63 the numerical form will be used. If no_name is 1 then the numerical
64 form will always be used.
65 OBJ_cmp() compares a to b. If the two are identical 0 is returned.
67 OBJ_dup() returns a copy of o.
69 OBJ_create() adds a new object to the internal table. oid is the
71 numerical form of the object, sn the short name and ln the long name. A
72 new NID is returned for the created object.
73 OBJ_cleanup() cleans up OpenSSLs internal object table: this should be
75 called before an application exits if any new objects were added using
76 OBJ_create().
77
79 Objects in OpenSSL can have a short name, a long name and a numerical
80 identifier (NID) associated with them. A standard set of objects is
81 represented in an internal table. The appropriate values are defined in
82 the header file objects.h.
83 For example the OID for commonName has the following definitions:
85 #define SN_commonName "CN"
87 #define LN_commonName "commonName"
88 #define NID_commonName 13
89 New objects can be added by calling OBJ_create().
91 Table objects have certain advantages over other objects: for example
93 their NIDs can be used in a C language switch statement. They are also
94 static constant structures which are shared: that is there is only a
95 single constant structure for each table object.
96 Objects which are not in the table have the NID value NID_undef.
98 Objects do not need to be in the internal tables to be processed, the
100 functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical
101 form of an OID.
102 Some objects are used to represent algorithms which do not have a
104 corresponding ASN.1 OBJECT IDENTIFIER encoding (for example no OID
105 currently exists for a particular algorithm). As a result they cannot
106 be encoded or decoded as part of ASN.1 structures. Applications can
107 determine if there is a corresponding OBJECT IDENTIFIER by checking
108 OBJ_length() is not zero.
109 These functions cannot return const because an ASN1_OBJECT can
111 represent both an internal, constant, OID and a dynamically-created
112 one. The latter cannot be constant because it needs to be freed after
113 use.
114
116 Create an object for commonName:
117 ASN1_OBJECT *o;
119 o = OBJ_nid2obj(NID_commonName);
120 Check if an object is commonName
122 if (OBJ_obj2nid(obj) == NID_commonName)
124 /* Do something */
125 Create a new NID and initialize an object from it:
127 int new_nid;
129 ASN1_OBJECT *obj;
130 new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
132 obj = OBJ_nid2obj(new_nid);
134 Create a new object directly:
136 obj = OBJ_txt2obj("1.2.3.4", 1);
138
140 OBJ_obj2txt() is awkward and messy to use: it doesn't follow the
141 convention of other OpenSSL functions where the buffer can be set to
142 NULL to determine the amount of data that should be written. Instead
143 buf must point to a valid buffer and buf_len should be set to a
144 positive value. A buffer length of 80 should be more than enough to
145 handle any OID encountered in practice.
146
148 OBJ_nid2obj() returns an ASN1_OBJECT structure or NULL is an error
149 occurred. It returns a pointer to an internal table and does not
150 allocate memory; ASN1_OBJECT_free() will have no effect.
151 OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or NULL on error.
153 OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return a
155 NID or NID_undef on error.
156
158 ERR_get_error(3)
159
161 TBA
1621.0.2o 2019-09-10 OBJ_nid2obj(3)