/usr/man/cat.3/OBJ_dup.3(/usr/man/cat.3/OBJ_dup.3)
OBJ_nid2obj(3) OpenSSL OBJ_nid2obj(3)
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
#include <openssl/objects.h>
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. For convenience, OIDs are usually
represented in source code as numeric identifiers, or NIDs.
OpenSSL has an internal table of OIDs that are generated
when the library is built, and their corresponding NIDs are
available as defined constants. For the functions below,
application code should treat all returned values -- OIDs,
NIDs, or names -- as constants.
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 if 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.
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OBJ_nid2obj(3) OpenSSL OBJ_nid2obj(3)
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.
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OBJ_nid2obj(3) OpenSSL OBJ_nid2obj(3)
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.
Some objects are used to represent algorithms which do not
have a corresponding ASN.1 OBJECT IDENTIFIER encoding (for
example no OID currently exists for a particular algorithm).
As a result they cannot be encoded or decoded as part of
ASN.1 structures. Applications can determine if there is a
corresponding OBJECT IDENTIFIER by checking OBJ_length() is
not zero.
These functions cannot return const because an ASN1_OBJECT
can represent both an internal, constant, OID and a
dynamically-created one. The latter cannot be constant
because it needs to be freed after use.
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);
BUGS
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
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OBJ_nid2obj(3) OpenSSL OBJ_nid2obj(3)
error occurred. It returns a pointer to an internal table
and does not allocate memory; ASN1_OBJECT_free() will have
no effect.
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.
SEE ALSO
ERR_get_error(3)
HISTORY
TBA
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See also OBJ_cleanup(3)
See also OBJ_cmp(3)
See also OBJ_create(3)
See also OBJ_ln2nid(3)
See also OBJ_nid2ln(3)
See also OBJ_nid2obj(3)
See also OBJ_nid2sn(3)
See also OBJ_obj2nid(3)
See also OBJ_obj2txt(3)
See also OBJ_sn2nid(3)
See also OBJ_txt2nid(3)
See also OBJ_txt2obj(3)
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