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