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- =pod
- =head1 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
- =head1 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);
- =head1 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 B<n> to
- an ASN1_OBJECT structure, its long name and its short name respectively,
- or B<NULL> is an error occurred.
- OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() return the corresponding NID
- for the object B<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>. B<s> can be
- a long name, a short name or the numerical respresentation of an object.
- OBJ_txt2obj() converts the text string B<s> into an ASN1_OBJECT structure.
- If B<no_name> is 0 then long names and short names will be interpreted
- as well as numerical forms. If B<no_name> is 1 only the numerical form
- is acceptable.
- OBJ_obj2txt() converts the B<ASN1_OBJECT> B<a> into a textual representation.
- The representation is written as a null terminated string to B<buf>
- at most B<buf_len> bytes are written, truncating the result if necessary.
- The total amount of space required is returned. If B<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 B<no_name> is 1 then the numerical
- form will always be used.
- OBJ_cmp() compares B<a> to B<b>. If the two are identical 0 is returned.
- OBJ_dup() returns a copy of B<o>.
- OBJ_create() adds a new object to the internal table. B<oid> is the
- numerical form of the object, B<sn> the short name and B<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().
- =head1 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 B<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.
- =head1 EXAMPLES
- Create an object for B<commonName>:
- ASN1_OBJECT *o;
- o = OBJ_nid2obj(NID_commonName);
- Check if an object is B<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);
- =head1 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 B<NULL> to determine the amount of data that should be written.
- Instead B<buf> must point to a valid buffer and B<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.
- =head1 RETURN VALUES
- OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an
- error occurred.
- OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL>
- on error.
- OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return
- a NID or B<NID_undef> on error.
- =head1 SEE ALSO
- L<ERR_get_error(3)|ERR_get_error(3)>
- =head1 HISTORY
- TBA
- =cut
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