Use DN objects instead of strings

* Convert every string specifying a DN into a DN object

* Every place a dn was manipulated in some fashion it was replaced by
  the use of DN operators

* Add new DNParam parameter type for parameters which are DN's

* DN objects are used 100% of the time throughout the entire data
  pipeline whenever something is logically a dn.

* Many classes now enforce DN usage for their attributes which are
  dn's. This is implmented via ipautil.dn_attribute_property(). The
  only permitted types for a class attribute specified to be a DN are
  either None or a DN object.

* Require that every place a dn is used it must be a DN object.
  This translates into lot of::

    assert isinstance(dn, DN)

  sprinkled through out the code. Maintaining these asserts is
  valuable to preserve DN type enforcement. The asserts can be
  disabled in production.

  The goal of 100% DN usage 100% of the time has been realized, these
  asserts are meant to preserve that.

  The asserts also proved valuable in detecting functions which did
  not obey their function signatures, such as the baseldap pre and
  post callbacks.

* Moved ipalib.dn to ipapython.dn because DN class is shared with all
  components, not just the server which uses ipalib.

* All API's now accept DN's natively, no need to convert to str (or
  unicode).

* Removed ipalib.encoder and encode/decode decorators. Type conversion
  is now explicitly performed in each IPASimpleLDAPObject method which
  emulates a ldap.SimpleLDAPObject method.

* Entity & Entry classes now utilize DN's

* Removed __getattr__ in Entity & Entity clases. There were two
  problems with it. It presented synthetic Python object attributes
  based on the current LDAP data it contained. There is no way to
  validate synthetic attributes using code checkers, you can't search
  the code to find LDAP attribute accesses (because synthetic
  attriutes look like Python attributes instead of LDAP data) and
  error handling is circumscribed. Secondly __getattr__ was hiding
  Python internal methods which broke class semantics.

* Replace use of methods inherited from ldap.SimpleLDAPObject via
  IPAdmin class with IPAdmin methods. Directly using inherited methods
  was causing us to bypass IPA logic. Mostly this meant replacing the
  use of search_s() with getEntry() or getList(). Similarly direct
  access of the LDAP data in classes using IPAdmin were replaced with
  calls to getValue() or getValues().

* Objects returned by ldap2.find_entries() are now compatible with
  either the python-ldap access methodology or the Entity/Entry access
  methodology.

* All ldap operations now funnel through the common
  IPASimpleLDAPObject giving us a single location where we interface
  to python-ldap and perform conversions.

* The above 4 modifications means we've greatly reduced the
  proliferation of multiple inconsistent ways to perform LDAP
  operations. We are well on the way to having a single API in IPA for
  doing LDAP (a long range goal).

* All certificate subject bases are now DN's

* DN objects were enhanced thusly:
  - find, rfind, index, rindex, replace and insert methods were added
  - AVA, RDN and DN classes were refactored in immutable and mutable
    variants, the mutable variants are EditableAVA, EditableRDN and
    EditableDN. By default we use the immutable variants preserving
    important semantics. To edit a DN cast it to an EditableDN and
    cast it back to DN when done editing. These issues are fully
    described in other documentation.
  - first_key_match was removed
  - DN equalty comparison permits comparison to a basestring

* Fixed ldapupdate to work with DN's. This work included:
  - Enhance test_updates.py to do more checking after applying
    update. Add test for update_from_dict(). Convert code to use
    unittest classes.
  - Consolidated duplicate code.
  - Moved code which should have been in the class into the class.
  - Fix the handling of the 'deleteentry' update action. It's no longer
    necessary to supply fake attributes to make it work. Detect case
    where subsequent update applies a change to entry previously marked
    for deletetion. General clean-up and simplification of the
    'deleteentry' logic.
  - Rewrote a couple of functions to be clearer and more Pythonic.
  - Added documentation on the data structure being used.
  - Simplfy the use of update_from_dict()

* Removed all usage of get_schema() which was being called prior to
  accessing the .schema attribute of an object. If a class is using
  internal lazy loading as an optimization it's not right to require
  users of the interface to be aware of internal
  optimization's. schema is now a property and when the schema
  property is accessed it calls a private internal method to perform
  the lazy loading.

* Added SchemaCache class to cache the schema's from individual
  servers. This was done because of the observation we talk to
  different LDAP servers, each of which may have it's own
  schema. Previously we globally cached the schema from the first
  server we connected to and returned that schema in all contexts. The
  cache includes controls to invalidate it thus forcing a schema
  refresh.

* Schema caching is now senstive to the run time context. During
  install and upgrade the schema can change leading to errors due to
  out-of-date cached schema. The schema cache is refreshed in these
  contexts.

* We are aware of the LDAP syntax of all LDAP attributes. Every
  attribute returned from an LDAP operation is passed through a
  central table look-up based on it's LDAP syntax. The table key is
  the LDAP syntax it's value is a Python callable that returns a
  Python object matching the LDAP syntax. There are a handful of LDAP
  attributes whose syntax is historically incorrect
  (e.g. DistguishedNames that are defined as DirectoryStrings). The
  table driven conversion mechanism is augmented with a table of
  hard coded exceptions.

  Currently only the following conversions occur via the table:

  - dn's are converted to DN objects

  - binary objects are converted to Python str objects (IPA
    convention).

  - everything else is converted to unicode using UTF-8 decoding (IPA
    convention).

  However, now that the table driven conversion mechanism is in place
  it would be trivial to do things such as converting attributes
  which have LDAP integer syntax into a Python integer, etc.

* Expected values in the unit tests which are a DN no longer need to
  use lambda expressions to promote the returned value to a DN for
  equality comparison. The return value is automatically promoted to
  a DN. The lambda expressions have been removed making the code much
  simpler and easier to read.

* Add class level logging to a number of classes which did not support
  logging, less need for use of root_logger.

* Remove ipaserver/conn.py, it was unused.

* Consolidated duplicate code wherever it was found.

* Fixed many places that used string concatenation to form a new
  string rather than string formatting operators. This is necessary
  because string formatting converts it's arguments to a string prior
  to building the result string. You can't concatenate a string and a
  non-string.

* Simplify logic in rename_managed plugin. Use DN operators to edit
  dn's.

* The live version of ipa-ldap-updater did not generate a log file.
  The offline version did, now both do.

https://fedorahosted.org/freeipa/ticket/1670
https://fedorahosted.org/freeipa/ticket/1671
https://fedorahosted.org/freeipa/ticket/1672
https://fedorahosted.org/freeipa/ticket/1673
https://fedorahosted.org/freeipa/ticket/1674
https://fedorahosted.org/freeipa/ticket/1392
https://fedorahosted.org/freeipa/ticket/2872

1 files changed, 124 insertions, 64 deletions

diff --git a/ipalib/plugins/baseldap.py b/ipalib/plugins/baseldap.py
index 32dae5160..e05f59ff4 100644
--- a/ipalib/plugins/baseldap.py
+++ b/ipalib/plugins/baseldap.py
@@ -34,7 +34,7 @@ from ipalib.cli import to_cli, from_cli
 from ipalib import output
 from ipalib.text import _
 from ipalib.util import json_serialize, validate_hostname
-from ipalib.dn import *
+from ipapython.dn import DN, RDN
 
 global_output_params = (
     Flag('has_password',
@@ -200,6 +200,7 @@ def validate_attribute(ugettext, name, attr):
         raise errors.ValidationError(name=name, error='Invalid format. Should be name=value')
 
 def get_effective_rights(ldap, dn, attrs=None):
+    assert isinstance(dn, DN)
     if attrs is None:
         attrs = ['*', 'nsaccountlock', 'cospriority']
     rights = ldap.get_effective_rights(dn, attrs)
@@ -332,6 +333,7 @@ def add_external_pre_callback(membertype, ldap, dn, keys, options):
 
     membertype is the type of member
     """
+    assert isinstance(dn, DN)
     # validate hostname with allowed underscore characters, non-fqdn
     # hostnames are allowed
     def validate_host(hostname):
@@ -361,12 +363,14 @@ def add_external_post_callback(memberattr, membertype, externalattr, ldap, compl
     membertype is the type of member: user,
     externalattr is one of externaluser,
     """
+    assert isinstance(dn, DN)
     completed_external = 0
     normalize = options.get('external_callback_normalize', True)
     # Sift through the failures. We assume that these are all
     # entries that aren't stored in IPA, aka external entries.
     if memberattr in failed and membertype in failed[memberattr]:
         (dn, entry_attrs_) = ldap.get_entry(dn, [externalattr])
+        assert isinstance(dn, DN)
         members = entry_attrs.get(memberattr, [])
         external_entries = entry_attrs_.get(externalattr, [])
         lc_external_entries = set(e.lower() for e in external_entries)
@@ -374,6 +378,7 @@ def add_external_post_callback(memberattr, membertype, externalattr, ldap, compl
         for entry in failed[memberattr][membertype]:
             membername = entry[0].lower()
             member_dn = api.Object[membertype].get_dn(membername)
+            assert isinstance(member_dn, DN)
             if (membername not in lc_external_entries and
                 member_dn not in members):
                 # Not an IPA entry, assume external
@@ -406,6 +411,7 @@ def add_external_post_callback(memberattr, membertype, externalattr, ldap, compl
     return (completed + completed_external, dn)
 
 def remove_external_post_callback(memberattr, membertype, externalattr, ldap, completed, failed, dn, entry_attrs, *keys, **options):
+    assert isinstance(dn, DN)
     # Run through the failures and gracefully remove any member defined
     # as an external member.
     if memberattr in failed and membertype in failed[memberattr]:
@@ -440,7 +446,7 @@ def host_is_master(ldap, fqdn):
 
     Raises an exception if a master, otherwise returns nothing.
     """
-    master_dn = str(DN('cn=%s' % fqdn, 'cn=masters,cn=ipa,cn=etc', api.env.basedn))
+    master_dn = DN(('cn', fqdn), ('cn', 'masters'), ('cn', 'ipa'), ('cn', 'etc'), api.env.basedn)
     try:
         (dn, entry_attrs) = ldap.get_entry(master_dn, ['objectclass'])
         raise errors.ValidationError(name='hostname', error=_('An IPA master host cannot be deleted or disabled'))
@@ -518,9 +524,11 @@ class LDAPObject(Object):
             return self.backend.make_dn_from_attr(
                 self.primary_key.name, keys[-1], parent_dn
             )
+        assert isinstance(parent_dn, DN)
         return parent_dn
 
     def get_primary_key_from_dn(self, dn):
+        assert isinstance(dn, DN)
         try:
             if self.rdn_attribute:
                 (dn, entry_attrs) = self.backend.get_entry(
@@ -532,8 +540,6 @@ class LDAPObject(Object):
                     return ''
         except errors.NotFound:
             pass
-        # DN object assures we're returning a decoded (unescaped) value
-        dn = DN(dn)
         try:
             return dn[self.primary_key.name]
         except KeyError:
@@ -567,7 +573,7 @@ class LDAPObject(Object):
             for member in entry_attrs.setdefault(attr, []):
                 for ldap_obj_name in self.attribute_members[attr]:
                     ldap_obj = self.api.Object[ldap_obj_name]
-                    if member.find(ldap_obj.container_dn) > 0:
+                    if ldap_obj.container_dn in member:
                         new_attr = '%s_%s' % (attr, ldap_obj.name)
                         entry_attrs.setdefault(new_attr, []).append(
                             ldap_obj.get_primary_key_from_dn(member)
@@ -623,7 +629,6 @@ class LDAPObject(Object):
 
     def __json__(self):
         ldap = self.backend
-        ldap.get_schema()
         json_dict = dict(
             (a, getattr(self, a)) for a in self.json_friendly_attributes
         )
@@ -777,52 +782,47 @@ last, after all sets and adds."""),
 
     _callback_registry = dict(pre={}, post={}, exc={}, interactive_prompt={})
 
-    def _convert_2_dict(self, attrs):
+    def _convert_2_dict(self, ldap, attrs):
         """
         Convert a string in the form of name/value pairs into a dictionary.
 
         :param attrs: A list of name/value pair strings, in the "name=value"
             format. May also be a single string, or None.
         """
-        if attrs is None:
-            return {}
-
-        if not isinstance(attrs, (tuple, list)):
-            attrs = [attrs]
 
         newdict = {}
+        if attrs is None:
+            attrs = []
+        elif not type(attrs) in (list, tuple):
+            attrs = [attrs]
         for a in attrs:
-            m = re.match("^\s*(?P<attr>.*?)\s*=\s*(?P<value>.*?)\s*$", a)
-            attr = str(m.group('attr').lower())
-            value = m.group('value')
-
+            m = re.match("\s*(.*?)\s*=\s*(.*?)\s*$", a)
+            attr = str(m.group(1)).lower()
+            value = m.group(2)
             if attr in self.obj.params and attr not in self.params:
                 # The attribute is managed by IPA, but it didn't get cloned
                 # to the command. This happens with no_update/no_create attrs.
                 raise errors.ValidationError(
                     name=attr, error=_('attribute is not configurable'))
+            if len(value) == 0:
+                # None means "delete this attribute"
+                value = None
 
-            newdict.setdefault(attr, []).append(value)
+            if ldap.has_dn_syntax(attr):
+                value = DN(value)
 
+            if attr in newdict:
+                if type(value) in (tuple,):
+                    newdict[attr] += list(value)
+                else:
+                    newdict[attr].append(value)
+            else:
+                if type(value) in (tuple,):
+                    newdict[attr] = list(value)
+                else:
+                    newdict[attr] = [value]
         return newdict
 
-    def _convert_entry(self, entry_attrs):
-        result = {}
-        for attr, val in entry_attrs.iteritems():
-            if val is None:
-                val = []
-            elif not isinstance(val, (tuple, list)):
-                val = [val]
-
-            result[attr] = []
-            for v in val:
-                if isinstance(v, str):
-                    # This is a Binary value, base64 encode it
-                    v = base64.b64encode(v)
-                result[attr].append(unicode(v))
-
-        return result
-
     def process_attr_options(self, entry_attrs, dn, keys, options):
         """
         Process all --setattr, --addattr, and --delattr options and add the
@@ -847,14 +847,15 @@ last, after all sets and adds."""),
         :param keys: List of command arguments
         :param options: List of options
         """
+
         if all(k not in options for k in ("setattr", "addattr", "delattr")):
             return
 
         ldap = self.obj.backend
 
-        adddict = self._convert_2_dict(options.get('addattr', []))
-        setdict = self._convert_2_dict(options.get('setattr', []))
-        deldict = self._convert_2_dict(options.get('delattr', []))
+        adddict = self._convert_2_dict(ldap, options.get('addattr', []))
+        setdict = self._convert_2_dict(ldap, options.get('setattr', []))
+        deldict = self._convert_2_dict(ldap, options.get('delattr', []))
 
         setattrs = set(setdict.keys())
         addattrs = set(adddict.keys())
@@ -865,24 +866,24 @@ last, after all sets and adds."""),
             direct_del = delattrs
             needldapattrs = []
         else:
+            assert isinstance(dn, DN)
             direct_add = setattrs & addattrs
             direct_del = setattrs & delattrs
             needldapattrs = list((addattrs | delattrs) - setattrs)
 
-        mod_attrs = self._convert_entry(entry_attrs)
-
         for attr, val in setdict.iteritems():
-            mod_attrs[attr] = val
+            entry_attrs[attr] = val
 
         for attr in direct_add:
-            mod_attrs.setdefault(attr, []).extend(adddict[attr])
+            entry_attrs.setdefault(attr, []).extend(adddict[attr])
 
         for attr in direct_del:
             for delval in deldict[attr]:
                 try:
-                    mod_attrs[attr].remove(delval)
+                    entry_attrs[attr].remove(delval)
                 except ValueError:
-                    raise errors.AttrValueNotFound(attr=attr, value=delval)
+                    raise errors.AttrValueNotFound(attr=attr,
+                                                   value=delval)
 
         if needldapattrs:
             try:
@@ -901,27 +902,28 @@ last, after all sets and adds."""),
                 raise errors.ValidationError(name=del_nonexisting.pop(),
                     error=_('No such attribute on this entry'))
 
-            old_entry = self._convert_entry(old_entry)
-
             for attr in needldapattrs:
-                mod_attrs[attr] = old_entry.get(attr, [])
+                entry_attrs[attr] = old_entry.get(attr, [])
 
                 if attr in addattrs:
-                    mod_attrs[attr].extend(adddict.get(attr, []))
+                    entry_attrs[attr].extend(adddict.get(attr, []))
 
                 for delval in deldict.get(attr, []):
                     try:
-                        mod_attrs[attr].remove(delval)
+                        entry_attrs[attr].remove(delval)
                     except ValueError:
+                        if isinstance(delval, str):
+                            # This is a Binary value, base64 encode it
+                            delval = unicode(base64.b64encode(delval))
                         raise errors.AttrValueNotFound(attr=attr, value=delval)
 
         # normalize all values
         changedattrs = setattrs | addattrs | delattrs
         for attr in changedattrs:
-            value = mod_attrs[attr]
             if attr in self.params and self.params[attr].attribute:
-                param = self.params[attr]
                 # convert single-value params to scalars
+                param = self.params[attr]
+                value = entry_attrs[attr]
                 if not param.multivalue:
                     if len(value) == 1:
                         value = value[0]
@@ -931,19 +933,19 @@ last, after all sets and adds."""),
                         raise errors.OnlyOneValueAllowed(attr=attr)
                 # validate, convert and encode params
                 try:
-                    value = param(value)
+                   value = param(value)
                 except errors.ValidationError, err:
                     raise errors.ValidationError(name=attr, error=err.error)
                 except errors.ConversionError, err:
                     raise errors.ConversionError(name=attr, error=err.error)
+                entry_attrs[attr] = value
             else:
                 # unknown attribute: remove duplicite and invalid values
-                value = list(set([val for val in value if val]))
-                if not value:
-                    value = None
-                elif isinstance(value, (tuple, list)) and len(value) == 1:
-                    value = value[0]
-            entry_attrs[attr] = value
+                entry_attrs[attr] = list(set([val for val in entry_attrs[attr] if val]))
+                if not entry_attrs[attr]:
+                    entry_attrs[attr] = None
+                elif isinstance(entry_attrs[attr], (tuple, list)) and len(entry_attrs[attr]) == 1:
+                    entry_attrs[attr] = entry_attrs[attr][0]
 
     @classmethod
     def register_pre_callback(cls, callback, first=False):
@@ -1021,8 +1023,13 @@ class LDAPCreate(BaseLDAPCommand, crud.Create):
             entry_attrs[self.obj.uuid_attribute] = 'autogenerate'
 
         dn = self.obj.get_dn(*keys, **options)
+        assert isinstance(dn, DN)
         if self.obj.rdn_attribute:
-            if not dn.startswith('%s=' % self.obj.primary_key.name):
+            try:
+                dn_attr = dn[0].attr
+            except (IndexError, KeyError):
+                dn_attr = None
+            if dn_attr != self.obj.primary_key.name:
                 self.obj.handle_duplicate_entry(*keys)
             dn = ldap.make_dn(
                 entry_attrs, self.obj.rdn_attribute, self.obj.container_dn
@@ -1038,9 +1045,9 @@ class LDAPCreate(BaseLDAPCommand, crud.Create):
         for callback in self.get_callbacks('pre'):
             dn = callback(
                 self, ldap, dn, entry_attrs, attrs_list, *keys, **options)
+            assert isinstance(dn, DN)
 
         _check_single_value_attrs(self.params, entry_attrs)
-        ldap.get_schema()
         _check_limit_object_class(self.api.Backend.ldap2.schema.attribute_types(self.obj.limit_object_classes), entry_attrs.keys(), allow_only=True)
         _check_limit_object_class(self.api.Backend.ldap2.schema.attribute_types(self.obj.disallow_object_classes), entry_attrs.keys(), allow_only=False)
 
@@ -1074,16 +1081,19 @@ class LDAPCreate(BaseLDAPCommand, crud.Create):
                     self.obj.primary_key.name, keys[-1], object_class, attrs_list,
                     self.obj.container_dn
                 )
+                assert isinstance(dn, DN)
             else:
                 (dn, entry_attrs) = self._exc_wrapper(keys, options, ldap.get_entry)(
                     dn, attrs_list, normalize=self.obj.normalize_dn
                 )
+                assert isinstance(dn, DN)
         except errors.NotFound:
             self.obj.handle_not_found(*keys)
 
         for callback in self.get_callbacks('post'):
             dn = callback(self, ldap, dn, entry_attrs, *keys, **options)
 
+        assert isinstance(dn, DN)
         entry_attrs['dn'] = dn
 
         self.obj.convert_attribute_members(entry_attrs, *keys, **options)
@@ -1092,9 +1102,11 @@ class LDAPCreate(BaseLDAPCommand, crud.Create):
         return dict(result=entry_attrs, value=u'')
 
     def pre_callback(self, ldap, dn, entry_attrs, attrs_list, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -1181,6 +1193,7 @@ class LDAPRetrieve(LDAPQuery):
         ldap = self.obj.backend
 
         dn = self.obj.get_dn(*keys, **options)
+        assert isinstance(dn, DN)
 
         if options.get('all', False):
             attrs_list = ['*'] + self.obj.default_attributes
@@ -1189,11 +1202,13 @@ class LDAPRetrieve(LDAPQuery):
 
         for callback in self.get_callbacks('pre'):
             dn = callback(self, ldap, dn, attrs_list, *keys, **options)
+            assert isinstance(dn, DN)
 
         try:
             (dn, entry_attrs) = self._exc_wrapper(keys, options, ldap.get_entry)(
                 dn, attrs_list, normalize=self.obj.normalize_dn
             )
+            assert isinstance(dn, DN)
         except errors.NotFound:
             self.obj.handle_not_found(*keys)
 
@@ -1202,17 +1217,21 @@ class LDAPRetrieve(LDAPQuery):
 
         for callback in self.get_callbacks('post'):
             dn = callback(self, ldap, dn, entry_attrs, *keys, **options)
+            assert isinstance(dn, DN)
 
         self.obj.convert_attribute_members(entry_attrs, *keys, **options)
+        assert isinstance(dn, DN)
         entry_attrs['dn'] = dn
         if self.obj.primary_key and keys[-1] is not None:
             return dict(result=entry_attrs, value=keys[-1])
         return dict(result=entry_attrs, value=u'')
 
     def pre_callback(self, ldap, dn, attrs_list, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -1261,6 +1280,7 @@ class LDAPUpdate(LDAPQuery, crud.Update):
             raise errors.EmptyModlist()
 
         dn = self.obj.get_dn(*keys, **options)
+        assert isinstance(dn, DN)
 
         entry_attrs = self.args_options_2_entry(**options)
 
@@ -1279,8 +1299,8 @@ class LDAPUpdate(LDAPQuery, crud.Update):
         for callback in self.get_callbacks('pre'):
             dn = callback(
                 self, ldap, dn, entry_attrs, attrs_list, *keys, **options)
+            assert isinstance(dn, DN)
 
-        ldap.get_schema()
         _check_limit_object_class(self.api.Backend.ldap2.schema.attribute_types(self.obj.limit_object_classes), entry_attrs.keys(), allow_only=True)
         _check_limit_object_class(self.api.Backend.ldap2.schema.attribute_types(self.obj.disallow_object_classes), entry_attrs.keys(), allow_only=False)
 
@@ -1294,10 +1314,10 @@ class LDAPUpdate(LDAPQuery, crud.Update):
             if self.obj.rdn_is_primary_key and self.obj.primary_key.name in entry_attrs:
                 # RDN change
                 self._exc_wrapper(keys, options, ldap.update_entry_rdn)(dn,
-                    unicode('%s=%s' % (self.obj.primary_key.name,
-                    entry_attrs[self.obj.primary_key.name])))
+                    RDN((self.obj.primary_key.name, entry_attrs[self.obj.primary_key.name])))
                 rdnkeys = keys[:-1] + (entry_attrs[self.obj.primary_key.name], )
                 dn = self.obj.get_dn(*rdnkeys)
+                assert isinstance(dn, DN)
                 del entry_attrs[self.obj.primary_key.name]
                 options['rdnupdate'] = True
                 rdnupdate = True
@@ -1306,6 +1326,7 @@ class LDAPUpdate(LDAPQuery, crud.Update):
             # to decide what to do. An EmptyModlist in this context doesn't
             # mean an error occurred, just that there were no other updates to
             # perform.
+            assert isinstance(dn, DN)
             self._exc_wrapper(keys, options, ldap.update_entry)(dn, entry_attrs, normalize=self.obj.normalize_dn)
         except errors.EmptyModlist, e:
             if not rdnupdate:
@@ -1327,6 +1348,7 @@ class LDAPUpdate(LDAPQuery, crud.Update):
 
         for callback in self.get_callbacks('post'):
             dn = callback(self, ldap, dn, entry_attrs, *keys, **options)
+            assert isinstance(dn, DN)
 
         self.obj.convert_attribute_members(entry_attrs, *keys, **options)
         if self.obj.primary_key and keys[-1] is not None:
@@ -1334,9 +1356,11 @@ class LDAPUpdate(LDAPQuery, crud.Update):
         return dict(result=entry_attrs, value=u'')
 
     def pre_callback(self, ldap, dn, entry_attrs, attrs_list, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -1360,11 +1384,14 @@ class LDAPDelete(LDAPMultiQuery):
         def delete_entry(pkey):
             nkeys = keys[:-1] + (pkey, )
             dn = self.obj.get_dn(*nkeys, **options)
+            assert isinstance(dn, DN)
 
             for callback in self.get_callbacks('pre'):
                 dn = callback(self, ldap, dn, *nkeys, **options)
+                assert isinstance(dn, DN)
 
             def delete_subtree(base_dn):
+                assert isinstance(base_dn, DN)
                 truncated = True
                 while truncated:
                     try:
@@ -1412,9 +1439,11 @@ class LDAPDelete(LDAPMultiQuery):
         return dict(result=dict(failed=u''), value=u'')
 
     def pre_callback(self, ldap, dn, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, dn, *keys, **options):
+        assert isinstance(dn, DN)
         return True
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -1495,14 +1524,17 @@ class LDAPAddMember(LDAPModMember):
         (member_dns, failed) = self.get_member_dns(**options)
 
         dn = self.obj.get_dn(*keys, **options)
+        assert isinstance(dn, DN)
 
         for callback in self.get_callbacks('pre'):
             dn = callback(self, ldap, dn, member_dns, failed, *keys, **options)
+            assert isinstance(dn, DN)
 
         completed = 0
         for (attr, objs) in member_dns.iteritems():
             for ldap_obj_name in objs:
                 for m_dn in member_dns[attr][ldap_obj_name]:
+                    assert isinstance(m_dn, DN)
                     if not m_dn:
                         continue
                     try:
@@ -1534,7 +1566,9 @@ class LDAPAddMember(LDAPModMember):
             (completed, dn) = callback(
                 self, ldap, completed, failed, dn, entry_attrs, *keys,
                 **options)
+            assert isinstance(dn, DN)
 
+        assert isinstance(dn, DN)
         entry_attrs['dn'] = dn
         self.obj.convert_attribute_members(entry_attrs, *keys, **options)
         return dict(
@@ -1544,9 +1578,11 @@ class LDAPAddMember(LDAPModMember):
         )
 
     def pre_callback(self, ldap, dn, found, not_found, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, completed, failed, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return (completed, dn)
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -1583,14 +1619,17 @@ class LDAPRemoveMember(LDAPModMember):
         (member_dns, failed) = self.get_member_dns(**options)
 
         dn = self.obj.get_dn(*keys, **options)
+        assert isinstance(dn, DN)
 
         for callback in self.get_callbacks('pre'):
             dn = callback(self, ldap, dn, member_dns, failed, *keys, **options)
+            assert isinstance(dn, DN)
 
         completed = 0
         for (attr, objs) in member_dns.iteritems():
             for ldap_obj_name, m_dns in objs.iteritems():
                 for m_dn in m_dns:
+                    assert isinstance(m_dn, DN)
                     if not m_dn:
                         continue
                     try:
@@ -1625,7 +1664,9 @@ class LDAPRemoveMember(LDAPModMember):
             (completed, dn) = callback(
                 self, ldap, completed, failed, dn, entry_attrs, *keys,
                 **options)
+            assert isinstance(dn, DN)
 
+        assert isinstance(dn, DN)
         entry_attrs['dn'] = dn
 
         self.obj.convert_attribute_members(entry_attrs, *keys, **options)
@@ -1636,9 +1677,11 @@ class LDAPRemoveMember(LDAPModMember):
         )
 
     def pre_callback(self, ldap, dn, found, not_found, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, completed, failed, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return (completed, dn)
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -1765,6 +1808,7 @@ class LDAPSearch(BaseLDAPCommand, crud.Search):
             base_dn = self.api.Object[self.obj.parent_object].get_dn(*args[:-1])
         else:
             base_dn = self.obj.container_dn
+        assert isinstance(base_dn, DN)
 
         search_kw = self.args_options_2_entry(**options)
 
@@ -1812,6 +1856,7 @@ class LDAPSearch(BaseLDAPCommand, crud.Search):
         for callback in self.get_callbacks('pre'):
             (filter, base_dn, scope) = callback(
                 self, ldap, filter, attrs_list, base_dn, scope, *args, **options)
+            assert isinstance(base_dn, DN)
 
         try:
             (entries, truncated) = self._exc_wrapper(args, options, ldap.find_entries)(
@@ -1827,14 +1872,16 @@ class LDAPSearch(BaseLDAPCommand, crud.Search):
 
         if self.sort_result_entries:
             if self.obj.primary_key:
-                sortfn=lambda x,y: cmp(x[1][self.obj.primary_key.name][0].lower(), y[1][self.obj.primary_key.name][0].lower())
-                entries.sort(sortfn)
+                def sort_key(x):
+                    return x[1][self.obj.primary_key.name][0].lower()
+                entries.sort(key=sort_key)
 
         if not options.get('raw', False):
             for e in entries:
                 self.obj.convert_attribute_members(e[1], *args, **options)
 
         for e in entries:
+            assert isinstance(e[0], DN)
             e[1]['dn'] = e[0]
         entries = [e for (dn, e) in entries]
 
@@ -1845,6 +1892,7 @@ class LDAPSearch(BaseLDAPCommand, crud.Search):
         )
 
     def pre_callback(self, ldap, filters, attrs_list, base_dn, scope, *args, **options):
+        assert isinstance(base_dn, DN)
         return (filters, base_dn, scope)
 
     def post_callback(self, ldap, entries, truncated, *args, **options):
@@ -1926,9 +1974,11 @@ class LDAPAddReverseMember(LDAPModReverseMember):
         # Ensure our target exists
         result = self.api.Command[self.show_command](keys[-1])['result']
         dn = result['dn']
+        assert isinstance(dn, DN)
 
         for callback in self.get_callbacks('pre'):
             dn = callback(self, ldap, dn, *keys, **options)
+            assert isinstance(dn, DN)
 
         if options.get('all', False):
             attrs_list = ['*'] + self.obj.default_attributes
@@ -1967,7 +2017,9 @@ class LDAPAddReverseMember(LDAPModReverseMember):
             (completed, dn) = callback(
                 self, ldap, completed, failed, dn, entry_attrs, *keys,
                 **options)
+            assert isinstance(dn, DN)
 
+        assert isinstance(dn, DN)
         entry_attrs['dn'] = dn
         return dict(
             completed=completed,
@@ -1976,9 +2028,11 @@ class LDAPAddReverseMember(LDAPModReverseMember):
         )
 
     def pre_callback(self, ldap, dn, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, completed, failed, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return (completed, dn)
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):
@@ -2022,9 +2076,11 @@ class LDAPRemoveReverseMember(LDAPModReverseMember):
         # Ensure our target exists
         result = self.api.Command[self.show_command](keys[-1])['result']
         dn = result['dn']
+        assert isinstance(dn, DN)
 
         for callback in self.get_callbacks('pre'):
             dn = callback(self, ldap, dn, *keys, **options)
+            assert isinstance(dn, DN)
 
         if options.get('all', False):
             attrs_list = ['*'] + self.obj.default_attributes
@@ -2063,7 +2119,9 @@ class LDAPRemoveReverseMember(LDAPModReverseMember):
             (completed, dn) = callback(
                 self, ldap, completed, failed, dn, entry_attrs, *keys,
                 **options)
+            assert isinstance(dn, DN)
 
+        assert isinstance(dn, DN)
         entry_attrs['dn'] = dn
         return dict(
             completed=completed,
@@ -2072,9 +2130,11 @@ class LDAPRemoveReverseMember(LDAPModReverseMember):
         )
 
     def pre_callback(self, ldap, dn, *keys, **options):
+        assert isinstance(dn, DN)
         return dn
 
     def post_callback(self, ldap, completed, failed, dn, entry_attrs, *keys, **options):
+        assert isinstance(dn, DN)
         return (completed, dn)
 
     def exc_callback(self, keys, options, exc, call_func, *call_args, **call_kwargs):