diff options
Diffstat (limited to 'crypto/openssl/doc/crypto/OBJ_nid2obj.pod')
| -rw-r--r-- | crypto/openssl/doc/crypto/OBJ_nid2obj.pod | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/crypto/openssl/doc/crypto/OBJ_nid2obj.pod b/crypto/openssl/doc/crypto/OBJ_nid2obj.pod index 1e45dd4..b8d2896 100644 --- a/crypto/openssl/doc/crypto/OBJ_nid2obj.pod +++ b/crypto/openssl/doc/crypto/OBJ_nid2obj.pod @@ -33,6 +33,12 @@ functions 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 B<NID>s. 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 B<n> to an ASN1_OBJECT structure, its long name and its short name respectively, @@ -96,6 +102,16 @@ 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 B<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 B<const> because an B<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. + =head1 EXAMPLES Create an object for B<commonName>: @@ -106,12 +122,13 @@ Create an object for B<commonName>: Check if an object is B<commonName> if (OBJ_obj2nid(obj) == NID_commonName) - /* Do something */ + /* 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); @@ -133,6 +150,8 @@ than enough to handle any OID encountered in practice. OBJ_nid2obj() returns an B<ASN1_OBJECT> structure or B<NULL> is an 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 B<NULL> on error. |
