NAME
OBJ_nid2obj, OBJ_nid2ln, OBJ_nid2sn, OBJ_obj2nid, OBJ_txt2nid, OBJ_ln2nid, OBJ_sn2nid, OBJ_cmp, OBJ_dup, OBJ_txt2obj, OBJ_obj2txt, OBJ_create, OBJ_cleanup — ASN1 object utility functions
Synopsis
ASN1_OBJECT * OBJ_nid2obj(int n);
const
char * OBJ_nid2ln(int n);
const char * OBJ_nid2sn(int
n);
int OBJ_obj2nid(const ASN1_OBJECT *o);
int
OBJ_ln2nid(const char *ln);
int OBJ_sn2nid(const char
*sn);
int OBJ_txt2nid(const char *s);
ASN1_OBJECT
* OBJ_txt2obj(const char *s, int no_name);
int OBJ_obj2txt(char
*buf, int buf_len, const ASN1_OBJECT *a, int no_name);
int
OBJ_cmp(const ASN1_OBJECT *a,const ASN1_OBJECT *b);
ASN1_OBJECT
* OBJ_dup(const ASN1_OBJECT *o);
int OBJ_create(const
char *oid,const char *sn,const char *ln);
void OBJ_cleanup(void);
DESCRIPTION
The ASN1 object utility functions process ASN1_OBJECT structures
which are a representation of the ASN1 OBJECT IDENTIFIER (OID) type.
OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID n to
an ASN1_OBJECT structure, its long name and its short name respectively,
or NULL is an error occurred.
OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding
NID for the object o, the long name <ln> or
the short name <sn> respectively or NID_undef
if an error occurred.
OBJ_txt2nid() returns NID corresponding to text string <s>. s can
be a long name, a short name or the numerical respresentation of
an object.
OBJ_txt2obj() converts the text string s into
an ASN1_OBJECT structure. If no_name is 0 then
long names and short names will be interpreted as well as numerical
forms. If no_name is 1 only the numerical form
is acceptable.
OBJ_obj2txt() converts the ASN1_OBJECT a into
a textual representation. The representation is written as a null
terminated string to buf at most buf_len bytes
are written, truncating the result if necessary. The total amount
of space required is returned. If no_name is
0 then if the object has a long or short name then that will be
used, otherwise the numerical form will be used. If no_name is
1 then the numerical form will always be used.
OBJ_cmp() compares a to b.
If the two are identical 0 is returned.
OBJ_dup() returns a copy of o.
OBJ_create() adds a new object to the internal table. oid is
the numerical form of the object, sn the short name
and ln the long name. A new NID is returned
for the created object.
OBJ_cleanup() cleans up OpenSSLs internal object table: this
should be called before an application exits if any new objects
were added using OBJ_create().
NOTES
Objects in OpenSSL can have a short name, a long name and
a numerical identifier (NID) associated with them. A standard set
of objects is represented in an internal table. The appropriate
values are defined in the header file objects.h.
For example the OID for commonName has the following definitions:
#define SN_commonName "CN"
#define LN_commonName "commonName"
#define NID_commonName 13 |
New objects can be added by calling OBJ_create().
Table objects have certain advantages over other objects:
for example their NIDs can be used in a C language switch statement.
They are also static constant structures which are shared: that
is there is only a single constant structure for each table object.
Objects which are not in the table have the NID value NID_undef.
Objects do not need to be in the internal tables to be processed,
the functions OBJ_txt2obj() and OBJ_obj2txt() can process the numerical
form of an OID.
EXAMPLES
Create an object for commonName:
ASN1_OBJECT *o;
o = OBJ_nid2obj(NID_commonName); |
Check if an object is commonName
if (OBJ_obj2nid(obj) == NID_commonName)
/* Do something */ |
Create a new NID and initialize an object from it:
int new_nid;
ASN1_OBJECT *obj;
new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
obj = OBJ_nid2obj(new_nid);
Create a new object directly:
obj = OBJ_txt2obj("1.2.3.4", 1); |
Restrictions
OBJ_obj2txt() is awkward and messy to use: it doesn't follow
the convention of other OpenSSL functions where the buffer can be
set to NULL to determine the amount of data
that should be written. Instead buf must point
to a valid buffer and buf_len should be set
to a positive value. A buffer length of 80 should be more than enough
to handle any OID encountered in practice.
RETURN VALUES
OBJ_nid2obj() returns an ASN1_OBJECT structure
or NULL is an error occurred.
OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or NULL on
error.
OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid()
return a NID or NID_undef on error.
