Fix DSA parameter generation control error

[oweals/openssl.git] / doc / crypto / OBJ_nid2obj.pod

diff --git a/doc/crypto/OBJ_nid2obj.pod b/doc/crypto/OBJ_nid2obj.pod
index 7388f2002bd538772424bd8a2b2cafd02f0db8de..b8d289673deedc16306bea8d99f502819010e325 100644 (file)
--- a/doc/crypto/OBJ_nid2obj.pod
+++ b/doc/crypto/OBJ_nid2obj.pod
@@ -33,11 +33,11 @@ functions
 
 The ASN1 object utility functions process ASN1_OBJECT structures which are
 a representation of the ASN1 OBJECT IDENTIFIER (OID) type.
-For convenience, OID's are usually represented in source code as numeric
-identifiers, or B<NID>'s.  OpenSSL has an internal table of OID's that
-are generated when the library is built, and their corresponding NID's
-are available as define'd constants.  For the functions below, application
-code should treat all returned values -- OID's, NID's, or names -- as
+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 
@@ -102,6 +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>:
@@ -112,7 +122,7 @@ 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:
 
@@ -136,13 +146,12 @@ 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.
 
-Many of the functions here should probably be changed to return B<const>
-pointers. But the lack of consistency makes that too awkward to do.
-
 =head1 RETURN VALUES
 
 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.