Schema support

[Hans A. <Han...@Ph...>]

I have finished a first version of schema support for python-ldap. 
There are four simple wrapper for the functions str2objectclass(), 
str2attributetype(), str2matchingrule(), and str2syntax() in the _ldap 
module (and thus in the ldap module --- I guess it would be a good idea 
to del() them from the ldap module in the ldap/__init__.py file...). 
These functions should not be used directly, since they are (probably) 
not thread safe.

There exists a new module ldap.schema, which proviedes the following 
functions/classes:

* Thread safe wrappers for the four C functions (str2xyz), which return 
  lists of entries which correspond to the C data types (defined in 
  ldap_schema.h). For thread safety, they simply use the _ldap_call()
  function (Michael, is this a good idea?).

* Four simple classes (attributeType, objectClass, ldapSyntax,
  matchingRule). Their constructors take a string description
  of the schema, pass it to the wrapper functions and fill in the
  object attributes. See RFC2252 for details.

* The class rootDSESchema (looking for a better name...), which takes
  an initialize()'d and simple_bind_s()'ed ldap object. The constructor 
  queries the rootDSE and fills the attributeTypes, objectClasses,
  ldapSyntaxes, and matchingRules which are known by the ldap server
  into 8 dictionaries: for each of the four classes, there is one
  dictionary which takes the oid's as keys (these are those funny
  "1.2.3.4" things, which are supposed to be unique), and one
  dictionary takes the names as keys. The latter is necessary, since
  for example, in objectClasses, the allowed or required attributes are
  referred to by name rather than by oid. The names of the
  dictionaries are:

        objectClasses
        objectClassesByName
        attributeTypes
        attributeTypesByName
        ldapSyntaxes
        ldapSyntaxesByName
        matchingRules
        matchingRulesByName

I've attached four files (a patch for setup.py, and the newly created 
files Modules/schema.c, Modules/schema.h, Lib/ldap/schema.py). 

Any comments? Does the user interface make sense? Could someone please 
try it with a _server_ different from OpenLDAP 2? As long as untested, 
I would say that it is only compatible with OpenLDAP --- there was some 
try/error involved in the RootDSE search...

Hans

-- 
Han...@Ph...