=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