freeipa/ipapython/ipaldap.py

# Authors: Rich Megginson <richm@redhat.com>
#          Rob Crittenden <rcritten@redhat.com>
#          John Dennis <jdennis@redhat.com>
#
# Copyright (C) 2007  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

import string
import time
import datetime
import shutil
from decimal import Decimal
from copy import deepcopy
import contextlib
import collections
import os
import pwd

import ldap
import ldap.sasl
import ldap.filter
from ldap.ldapobject import SimpleLDAPObject
from ldap.controls import SimplePagedResultsControl
import ldapurl

from ipalib import errors, _
from ipalib.constants import LDAP_GENERALIZED_TIME_FORMAT
from ipapython import ipautil
from ipapython.ipautil import (
    format_netloc, wait_for_open_socket, wait_for_open_ports, CIDict)
from ipapython.ipa_log_manager import log_mgr
from ipapython.dn import DN, RDN
from ipapython.dnsutil import DNSName

# Global variable to define SASL auth
SASL_GSSAPI = ldap.sasl.sasl({}, 'GSSAPI')

DEFAULT_TIMEOUT = 10
_debug_log_ldap = False

_missing = object()

# Autobind modes
AUTOBIND_AUTO = 1
AUTOBIND_ENABLED = 2
AUTOBIND_DISABLED = 3

def unicode_from_utf8(val):
    '''
    val is a UTF-8 encoded string, return a unicode object.
    '''
    return val.decode('utf-8')


def value_to_utf8(val):
    '''
    Coerce the val parameter to a UTF-8 encoded string representation
    of the val.
    '''

    # If val is not a string we need to convert it to a string
    # (specifically a unicode string). Naively we might think we need to
    # call str(val) to convert to a string. This is incorrect because if
    # val is already a unicode object then str() will call
    # encode(default_encoding) returning a str object encoded with
    # default_encoding. But we don't want to apply the default_encoding!
    # Rather we want to guarantee the val object has been converted to a
    # unicode string because from a unicode string we want to explicitly
    # encode to a str using our desired encoding (utf-8 in this case).
    #
    # Note: calling unicode on a unicode object simply returns the exact
    # same object (with it's ref count incremented). This means calling
    # unicode on a unicode object is effectively a no-op, thus it's not
    # inefficient.

    return unicode(val).encode('utf-8')

class _ServerSchema(object):
    '''
    Properties of a schema retrieved from an LDAP server.
    '''

    def __init__(self, server, schema):
        self.server = server
        self.schema = schema
        self.retrieve_timestamp = time.time()


class SchemaCache(object):
    '''
    Cache the schema's from individual LDAP servers.
    '''

    def __init__(self):
        self.log = log_mgr.get_logger(self)
        self.servers = {}

    def get_schema(self, url, conn, force_update=False):
        '''
        Return schema belonging to a specific LDAP server.

        For performance reasons the schema is retrieved once and
        cached unless force_update is True. force_update flushes the
        existing schema for the server from the cache and reacquires
        it.
        '''

        if force_update:
            self.flush(url)

        server_schema = self.servers.get(url)
        if server_schema is None:
            schema = self._retrieve_schema_from_server(url, conn)
            server_schema = _ServerSchema(url, schema)
            self.servers[url] = server_schema
        return server_schema.schema

    def flush(self, url):
        self.log.debug('flushing %s from SchemaCache', url)
        try:
            del self.servers[url]
        except KeyError:
            pass

    def _retrieve_schema_from_server(self, url, conn):
        """
        Retrieve the LDAP schema from the provided url and determine if
        User-Private Groups (upg) are configured.

        Bind using kerberos credentials. If in the context of the
        in-tree "lite" server then use the current ccache. If in the context of
        Apache then create a new ccache and bind using the Apache HTTP service
        principal.

        If a connection is provided then it the credentials bound to it are
        used. The connection is not closed when the request is done.
        """
        tmpdir = None
        assert conn is not None

        self.log.debug(
            'retrieving schema for SchemaCache url=%s conn=%s', url, conn)

        try:
            try:
                schema_entry = conn.search_s('cn=schema', ldap.SCOPE_BASE,
                    attrlist=['attributetypes', 'objectclasses'])[0]
            except ldap.NO_SUCH_OBJECT:
                # try different location for schema
                # openldap has schema located in cn=subschema
                self.log.debug('cn=schema not found, fallback to cn=subschema')
                schema_entry = conn.search_s('cn=subschema', ldap.SCOPE_BASE,
                    attrlist=['attributetypes', 'objectclasses'])[0]
        except ldap.SERVER_DOWN:
            raise errors.NetworkError(uri=url,
                               error=u'LDAP Server Down, unable to retrieve LDAP schema')
        except ldap.LDAPError as e:
            desc = e.args[0]['desc'].strip()
            info = e.args[0].get('info', '').strip()
            raise errors.DatabaseError(desc = u'uri=%s' % url,
                                info = u'Unable to retrieve LDAP schema: %s: %s' % (desc, info))
        except IndexError:
            # no 'cn=schema' entry in LDAP? some servers use 'cn=subschema'
            # TODO: DS uses 'cn=schema', support for other server?
            #       raise a more appropriate exception
            raise
        finally:
            if tmpdir:
                shutil.rmtree(tmpdir)

        return ldap.schema.SubSchema(schema_entry[1])

schema_cache = SchemaCache()


class LDAPEntry(collections.MutableMapping):
    __slots__ = ('_conn', '_dn', '_names', '_nice', '_raw', '_sync',
                 '_not_list', '_orig', '_raw_view', '_single_value_view')

    def __init__(self, _conn, _dn=None, _obj=None, **kwargs):
        """
        LDAPEntry constructor.

        Takes 1 to 3 positional arguments and an arbitrary number of keyword
        arguments. The 3 forms of positional arguments are:

          * LDAPEntry(entry) - create a shallow copy of an existing LDAPEntry.
          * LDAPEntry(dn, entry) - create a shallow copy of an existing
            LDAPEntry with a different DN.
          * LDAPEntry(conn, dn, mapping) - create a new LDAPEntry using the
            specified LDAPClient and DN and optionally initialize
            attributes from the specified mapping object.

        Keyword arguments can be used to override values of specific attributes.
        """
        super(LDAPEntry, self).__init__()

        if isinstance(_conn, LDAPEntry):
            assert _dn is None
            _dn = _conn
            _conn = _conn._conn
        assert isinstance(_conn, LDAPClient)

        if isinstance(_dn, LDAPEntry):
            assert _obj is None
            _obj = _dn
            _dn = _dn._dn
        assert isinstance(_dn, DN)

        if _obj is None:
            _obj = {}

        self._conn = _conn
        self._dn = _dn
        self._names = CIDict()
        self._nice = {}
        self._raw = {}
        self._sync = {}
        self._not_list = set()
        self._orig = {}
        self._raw_view = None
        self._single_value_view = None

        if isinstance(_obj, LDAPEntry):
            #pylint: disable=E1103
            self._not_list = set(_obj._not_list)
            self._orig = dict(_obj._orig)
            if _obj.conn is _conn:
                self._names = CIDict(_obj._names)
                self._nice = dict(_obj._nice)
                self._raw = dict(_obj._raw)
                self._sync = dict(_obj._sync)
            else:
                self.raw.update(_obj.raw)

            _obj = {}

        self.update(_obj, **kwargs)

    @property
    def conn(self):
        return self._conn

    @property
    def dn(self):
        return self._dn

    @dn.setter
    def dn(self, value):
        assert isinstance(value, DN)
        self._dn = value

    @property
    def raw(self):
        if self._raw_view is None:
            self._raw_view = RawLDAPEntryView(self)
        return self._raw_view

    @property
    def single_value(self):
        if self._single_value_view is None:
            self._single_value_view = SingleValueLDAPEntryView(self)
        return self._single_value_view

    def __repr__(self):
        data = dict(self._raw)
        data.update((k, v) for k, v in self._nice.iteritems() if v is not None)
        return '%s(%r, %r)' % (type(self).__name__, self._dn, data)

    def copy(self):
        return LDAPEntry(self)

    def _sync_attr(self, name):
        nice = self._nice[name]
        assert isinstance(nice, list)

        raw = self._raw[name]
        assert isinstance(raw, list)

        nice_sync, raw_sync = self._sync.setdefault(name, ([], []))
        if nice == nice_sync and raw == raw_sync:
            return

        nice_adds = set(nice) - set(nice_sync)
        nice_dels = set(nice_sync) - set(nice)
        raw_adds = set(raw) - set(raw_sync)
        raw_dels = set(raw_sync) - set(raw)

        for value in nice_dels:
            value = self._conn.encode(value)
            if value in raw_adds:
                continue
            raw.remove(value)

        for value in raw_dels:
            value = self._conn.decode(value, name)
            if value in nice_adds:
                continue
            nice.remove(value)

        for value in nice_adds:
            value = self._conn.encode(value)
            if value in raw_dels:
                continue
            raw.append(value)

        for value in raw_adds:
            value = self._conn.decode(value, name)
            if value in nice_dels:
                continue
            nice.append(value)

        self._sync[name] = (deepcopy(nice), deepcopy(raw))

        if len(nice) > 1:
            self._not_list.discard(name)

    def _attr_name(self, name):
        if not isinstance(name, basestring):
            raise TypeError(
                "attribute name must be unicode or str, got %s object %r" % (
                    name.__class__.__name__, name))

        if isinstance(name, str):
            name = name.decode('utf-8')

        return name

    def _add_attr_name(self, name):
        if name in self._names:
            return self._names[name]

        if self._conn.schema is not None:
            attrtype = self._conn.schema.get_obj(
                ldap.schema.AttributeType, name.encode('utf-8'))
            if attrtype is not None:
                for altname in attrtype.names:
                    altname = altname.decode('utf-8')
                    self._names[altname] = name

        self._names[name] = name

        for oldname in self._orig.keys():
            if self._names.get(oldname) == name:
                self._orig[name] = self._orig.pop(oldname)
                break

        return name

    def _set_nice(self, name, value):
        name = self._attr_name(name)
        name = self._add_attr_name(name)

        if not isinstance(value, list):
            if value is None:
                value = []
            else:
                value = [value]
            self._not_list.add(name)
        else:
            self._not_list.discard(name)

        if self._nice.get(name) is not value:
            self._nice[name] = value
            self._raw[name] = None
            self._sync.pop(name, None)

        if self._raw[name] is not None:
            self._sync_attr(name)

    def _set_raw(self, name, value):
        name = self._attr_name(name)

        if not isinstance(value, list):
            raise TypeError("%s value must be list, got %s object %r" % (
                name, value.__class__.__name__, value))
        for (i, item) in enumerate(value):
            if not isinstance(item, str):
                raise TypeError("%s[%d] value must be str, got %s object %r" % (
                    name, i, item.__class__.__name__, item))

        name = self._add_attr_name(name)

        if self._raw.get(name) is not value:
            self._raw[name] = value
            self._nice[name] = None
            self._sync.pop(name, None)

        if self._nice[name] is not None:
            self._sync_attr(name)

    def __setitem__(self, name, value):
        self._set_nice(name, value)

    def _get_attr_name(self, name):
        name = self._attr_name(name)
        name = self._names[name]
        return name

    def _get_nice(self, name):
        name = self._get_attr_name(name)

        value = self._nice[name]
        if value is None:
            value = self._nice[name] = []
        assert isinstance(value, list)

        if self._raw[name] is not None:
            self._sync_attr(name)

        if name in self._not_list:
            assert len(value) <= 1
            if value:
                value = value[0]
            else:
                value = None

        return value

    def _get_raw(self, name):
        name = self._get_attr_name(name)

        value = self._raw[name]
        if value is None:
            value = self._raw[name] = []
        assert isinstance(value, list)

        if self._nice[name] is not None:
            self._sync_attr(name)

        return value

    def __getitem__(self, name):
        return self._get_nice(name)

    def __delitem__(self, name):
        name = self._get_attr_name(name)

        for (altname, keyname) in self._names.items():
            if keyname == name:
                del self._names[altname]

        del self._nice[name]
        del self._raw[name]
        self._sync.pop(name, None)
        self._not_list.discard(name)

    def clear(self):
        self._names.clear()
        self._nice.clear()
        self._raw.clear()
        self._sync.clear()
        self._not_list.clear()

    def __len__(self):
        return len(self._nice)

    def __contains__(self, name):
        return name in self._names

    def has_key(self, name):
        return name in self

    def __eq__(self, other):
        if not isinstance(other, LDAPEntry):
            return NotImplemented
        return other is self

    def __ne__(self, other):
        if not isinstance(other, LDAPEntry):
            return NotImplemented
        return other is not self

    def reset_modlist(self, other=None):
        if other is None:
            other = self
        assert isinstance(other, LDAPEntry)
        self._orig = deepcopy(dict(other.raw))

    def generate_modlist(self):
        modlist = []

        names = set(self.iterkeys())
        names.update(self._orig)
        for name in names:
            new = self.raw.get(name, [])
            old = self._orig.get(name, [])
            if old and not new:
                modlist.append((ldap.MOD_DELETE, name, None))
                continue
            if not old and new:
                modlist.append((ldap.MOD_REPLACE, name, new))
                continue

            # We used to convert to sets and use difference to calculate
            # the changes but this did not preserve order which is important
            # particularly for schema
            adds = [value for value in new if value not in old]
            dels = [value for value in old if value not in new]
            if adds and self.conn.get_attribute_single_value(name):
                if len(adds) > 1:
                    raise errors.OnlyOneValueAllowed(attr=name)
                modlist.append((ldap.MOD_REPLACE, name, adds))
            else:
                if adds:
                    modlist.append((ldap.MOD_ADD, name, adds))
                if dels:
                    modlist.append((ldap.MOD_DELETE, name, dels))

        # Usually the modlist order does not matter.
        # However, for schema updates, we want 'attributetypes' before
        # 'objectclasses'.
        # A simple sort will ensure this.
        modlist.sort(key=lambda m: m[1].lower() != 'attributetypes')

        return modlist

    def __iter__(self):
        return iter(self._nice)


class LDAPEntryView(collections.MutableMapping):
    __slots__ = ('_entry',)

    def __init__(self, entry):
        assert isinstance(entry, LDAPEntry)
        self._entry = entry

    def __delitem__(self, name):
        del self._entry[name]

    def clear(self):
        self._entry.clear()

    def __iter__(self):
        return self._entry.iterkeys()

    def __len__(self):
        return len(self._entry)

    def __contains__(self, name):
        return name in self._entry

    def has_key(self, name):
        return name in self

class RawLDAPEntryView(LDAPEntryView):
    def __getitem__(self, name):
        return self._entry._get_raw(name)

    def __setitem__(self, name, value):
        self._entry._set_raw(name, value)

class SingleValueLDAPEntryView(LDAPEntryView):
    def __getitem__(self, name):
        value = self._entry[name]
        if not isinstance(value, list):
            # FIXME: remove when we enforce lists
            return value
        elif not value:
            return None
        elif len(value) == 1:
            return value[0]
        else:
            raise ValueError(
                '%s has %s values, one expected' % (name, len(value)))

    def __setitem__(self, name, value):
        if value is None:
            self._entry[name] = None
        else:
            self._entry[name] = [value]


class LDAPClient(object):
    """LDAP backend class

    This class abstracts a LDAP connection, providing methods that work with
    LADPEntries.

    The purpose of this class is to provide a boundary between IPA and
    python-ldap. In IPA we use IPA defined types because they are
    richer and are designed to meet our needs. We also require that we
    consistently use those types without exception. On the other hand
    python-ldap uses different types. The goal is to be able to have
    IPA code call python-ldap methods using the types native to
    IPA. This class accomplishes that goal by exposing python-ldap
    methods which take IPA types, convert them to python-ldap types,
    call python-ldap, and then convert the results returned by
    python-ldap into IPA types.
    """

    # rules for generating filters from entries
    MATCH_ANY = '|'   # (|(filter1)(filter2))
    MATCH_ALL = '&'   # (&(filter1)(filter2))
    MATCH_NONE = '!'  # (!(filter1)(filter2))

    # search scope for find_entries()
    SCOPE_BASE = ldap.SCOPE_BASE
    SCOPE_ONELEVEL = ldap.SCOPE_ONELEVEL
    SCOPE_SUBTREE = ldap.SCOPE_SUBTREE

    _SYNTAX_MAPPING = {
        '1.3.6.1.4.1.1466.115.121.1.1'   : str, # ACI item
        '1.3.6.1.4.1.1466.115.121.1.4'   : str, # Audio
        '1.3.6.1.4.1.1466.115.121.1.5'   : str, # Binary
        '1.3.6.1.4.1.1466.115.121.1.8'   : str, # Certificate
        '1.3.6.1.4.1.1466.115.121.1.9'   : str, # Certificate List
        '1.3.6.1.4.1.1466.115.121.1.10'  : str, # Certificate Pair
        '1.3.6.1.4.1.1466.115.121.1.12'  : DN,  # Distinguished Name
        '1.3.6.1.4.1.1466.115.121.1.23'  : str, # Fax
        '1.3.6.1.4.1.1466.115.121.1.24'  : datetime.datetime,
        '1.3.6.1.4.1.1466.115.121.1.28'  : str, # JPEG
        '1.3.6.1.4.1.1466.115.121.1.40'  : str, # OctetString (same as Binary)
        '1.3.6.1.4.1.1466.115.121.1.49'  : str, # Supported Algorithm
        '1.3.6.1.4.1.1466.115.121.1.51'  : str, # Teletext Terminal Identifier

        '2.16.840.1.113730.3.8.3.3'      : DN,  # enrolledBy
        '2.16.840.1.113730.3.8.3.18'     : DN,  # managedBy
        '2.16.840.1.113730.3.8.3.5'      : DN,  # memberUser
        '2.16.840.1.113730.3.8.3.7'      : DN,  # memberHost
        '2.16.840.1.113730.3.8.3.20'     : DN,  # memberService
        '2.16.840.1.113730.3.8.11.4'     : DN,  # ipaNTFallbackPrimaryGroup
        '2.16.840.1.113730.3.8.11.21'    : DN,  # ipaAllowToImpersonate
        '2.16.840.1.113730.3.8.11.22'    : DN,  # ipaAllowedTarget
        '2.16.840.1.113730.3.8.7.1'      : DN,  # memberAllowCmd
        '2.16.840.1.113730.3.8.7.2'      : DN,  # memberDenyCmd

        '2.16.840.1.113719.1.301.4.14.1' : DN,  # krbRealmReferences
        '2.16.840.1.113719.1.301.4.17.1' : DN,  # krbKdcServers
        '2.16.840.1.113719.1.301.4.18.1' : DN,  # krbPwdServers
        '2.16.840.1.113719.1.301.4.26.1' : DN,  # krbPrincipalReferences
        '2.16.840.1.113719.1.301.4.29.1' : DN,  # krbAdmServers
        '2.16.840.1.113719.1.301.4.36.1' : DN,  # krbPwdPolicyReference
        '2.16.840.1.113719.1.301.4.40.1' : DN,  # krbTicketPolicyReference
        '2.16.840.1.113719.1.301.4.41.1' : DN,  # krbSubTrees
        '2.16.840.1.113719.1.301.4.52.1' : DN,  # krbObjectReferences
        '2.16.840.1.113719.1.301.4.53.1' : DN,  # krbPrincContainerRef
    }

    # In most cases we lookup the syntax from the schema returned by
    # the server. However, sometimes attributes may not be defined in
    # the schema (e.g. extensibleObject which permits undefined
    # attributes), or the schema was incorrectly defined (i.e. giving
    # an attribute the syntax DirectoryString when in fact it's really
    # a DN). This (hopefully sparse) table allows us to trap these
    # anomalies and force them to be the syntax we know to be in use.
    #
    # FWIW, many entries under cn=config are undefined :-(

    _SYNTAX_OVERRIDE = CIDict({
        'managedtemplate': DN,
        'managedbase':     DN,
        'memberindirect':  DN,
        'memberofindirect':DN,
        'originscope':     DN,
        'idnsname':        DNSName,
        'idnssoamname':    DNSName,
        'idnssoarname':    DNSName,
        'dnszoneidnsname': DNSName,
        'nsds5replicalastupdatestart': unicode,
        'nsds5replicalastupdateend': unicode,
        'nsds5replicalastinitstart': unicode,
        'nsds5replicalastinitend': unicode,
    })
    _SINGLE_VALUE_OVERRIDE = CIDict({
        'nsslapd-ssl-check-hostname': True,
        'nsslapd-lookthroughlimit': True,
        'nsslapd-idlistscanlimit': True,
        'nsslapd-anonlimitsdn': True,
        'nsslapd-minssf-exclude-rootdse': True,
    })

    def __init__(self, ldap_uri, start_tls=False, force_schema_updates=False,
                 no_schema=False, decode_attrs=True):
        """Create LDAPClient object.

        :param ldap_uri: The LDAP URI to connect to
        :param start_tls: Use STARTTLS
        :param force_schema_updates:
            If true, this object will always request a new schema from the
            server. If false, a cached schema will be reused if it exists.

            Generally, it should be true if the API context is 'installer' or
            'updates', but it must be given explicitly since the API object
            is not always available
        :param no_schema: If true, schema is never requested from the server.
        :param decode_attrs:
            If true, attributes are decoded to Python types according to their
            syntax.
        """
        self.ldap_uri = ldap_uri
        self._start_tls = start_tls
        self._force_schema_updates = force_schema_updates
        self._no_schema = no_schema
        self._decode_attrs = decode_attrs

        self.log = log_mgr.get_logger(self)
        self._conn = None
        self._has_schema = False
        self._schema = None

        self._connect()

    @property
    def conn(self):
        return self._conn

    def _get_schema(self):
        if self._no_schema:
            return None

        if not self._has_schema:
            try:
                schema = schema_cache.get_schema(
                    self.ldap_uri, self.conn,
                    force_update=self._force_schema_updates)
            except (errors.ExecutionError, IndexError):
                schema = None

            # bypass ldap2's locking
            object.__setattr__(self, '_schema', schema)
            object.__setattr__(self, '_has_schema', True)

        return self._schema

    def _flush_schema(self):
        '''
        Force this instance to forget it's cached schema and reacquire
        it from the schema cache.
        '''

        # Currently this is called during bind operations to assure
        # we're working with valid schema for a specific
        # connection. This causes self._get_schema() to query the
        # schema cache for the server's schema passing along a flag
        # indicating if we're in a context that requires freshly
        # loading the schema vs. returning the last cached version of
        # the schema. If we're in a mode that permits use of
        # previously cached schema the flush and reacquire is a very
        # low cost operation.
        #
        # The schema is reacquired whenever this object is
        # instantiated or when binding occurs. The schema is not
        # reacquired for operations during a bound connection, it is
        # presumed schema cannot change during this interval. This
        # provides for maximum efficiency in contexts which do need
        # schema refreshing by only peforming the refresh inbetween
        # logical operations that have the potential to cause a schema
        # change.

        # bypass ldap2's locking
        object.__setattr__(self, '_has_schema', False)
        object.__setattr__(self, '_schema', None)

    def get_attribute_type(self, name_or_oid):
        if not self._decode_attrs:
            return str

        if isinstance(name_or_oid, unicode):
            name_or_oid = name_or_oid.encode('utf-8')

        # Is this a special case attribute?
        if name_or_oid in self._SYNTAX_OVERRIDE:
            return self._SYNTAX_OVERRIDE[name_or_oid]

        schema = self._get_schema()
        if schema is not None:
            # Try to lookup the syntax in the schema returned by the server
            obj = schema.get_obj(ldap.schema.AttributeType, name_or_oid)
            if obj is not None and obj.syntax in self._SYNTAX_MAPPING:
                return self._SYNTAX_MAPPING[obj.syntax]

        return unicode

    def has_dn_syntax(self, name_or_oid):
        """
        Check the schema to see if the attribute uses DN syntax.

        Returns True/False
        """
        return self.get_attribute_type(name_or_oid) is DN

    def get_attribute_single_value(self, name_or_oid):
        """
        Check the schema to see if the attribute is single-valued.

        If the attribute is in the schema then returns True/False

        If there is a problem loading the schema or the attribute is
        not in the schema return None
        """
        if isinstance(name_or_oid, unicode):
            name_or_oid = name_or_oid.encode('utf-8')

        if name_or_oid in self._SINGLE_VALUE_OVERRIDE:
            return self._SINGLE_VALUE_OVERRIDE[name_or_oid]

        schema = self._get_schema()
        if schema is not None:
            obj = schema.get_obj(ldap.schema.AttributeType, name_or_oid)
            if obj is not None:
                return obj.single_value

        return None

    def encode(self, val):
        """
        Encode attribute value to LDAP representation (str).
        """
        # Booleans are both an instance of bool and int, therefore
        # test for bool before int otherwise the int clause will be
        # entered for a boolean value instead of the boolean clause.
        if isinstance(val, bool):
            if val:
                return 'TRUE'
            else:
                return 'FALSE'
        elif isinstance(val, (unicode, float, int, long, Decimal, DN)):
            return value_to_utf8(val)
        elif isinstance(val, DNSName):
            return str(val)
        elif isinstance(val, str):
            return val
        elif isinstance(val, list):
            return [self.encode(m) for m in val]
        elif isinstance(val, tuple):
            return tuple(self.encode(m) for m in val)
        elif isinstance(val, dict):
            dct = dict((self.encode(k), self.encode(v)) for k, v in val.iteritems())
            return dct
        elif isinstance(val, datetime.datetime):
            return val.strftime(LDAP_GENERALIZED_TIME_FORMAT)
        elif val is None:
            return None
        else:
            raise TypeError("attempt to pass unsupported type to ldap, value=%s type=%s" %(val, type(val)))

    def decode(self, val, attr):
        """
        Decode attribute value from LDAP representation (str).
        """
        if isinstance(val, str):
            target_type = self.get_attribute_type(attr)
            try:
                if target_type is str:
                    return val
                elif target_type is unicode:
                    return val.decode('utf-8')
                elif target_type is datetime.datetime:
                    return datetime.datetime.strptime(val, LDAP_GENERALIZED_TIME_FORMAT)
                else:
                    return target_type(val)
            except Exception as e:
                msg = 'unable to convert the attribute %r value %r to type %s' % (attr, val, target_type)
                self.log.error(msg)
                raise ValueError(msg)
        elif isinstance(val, list):
            return [self.decode(m, attr) for m in val]
        elif isinstance(val, tuple):
            return tuple(self.decode(m, attr) for m in val)
        elif isinstance(val, dict):
            dct = dict((unicode_from_utf8(k), self.decode(v, k)) for k, v in val.iteritems())
            return dct
        elif val is None:
            return None
        else:
            raise TypeError("attempt to pass unsupported type from ldap, value=%s type=%s" %(val, type(val)))

    def _convert_result(self, result):
        '''
        result is a python-ldap result tuple of the form (dn, attrs),
        where dn is a string containing the dn (distinguished name) of
        the entry, and attrs is a dictionary containing the attributes
        associated with the entry. The keys of attrs are strings, and
        the associated values are lists of strings.

        We convert the tuple to an LDAPEntry object.
        '''

        ipa_result = []
        for dn_tuple in result:
            original_dn = dn_tuple[0]
            original_attrs = dn_tuple[1]

            # original_dn is None if referral instead of an entry was
            # returned from the LDAP server, we need to skip this item
            if original_dn is None:
                log_msg = 'Referral entry ignored: {ref}'\
                          .format(ref=str(original_attrs))
                self.log.debug(log_msg)

                continue

            ipa_entry = LDAPEntry(self, DN(original_dn))

            for attr, original_values in original_attrs.items():
                ipa_entry.raw[attr] = original_values
            ipa_entry.reset_modlist()

            ipa_result.append(ipa_entry)

        if _debug_log_ldap:
            self.log.debug('ldap.result: %s', ipa_result)
        return ipa_result

    @contextlib.contextmanager
    def error_handler(self, arg_desc=None):
        """Context manager that handles LDAPErrors
        """
        try:
            try:
                yield
            except ldap.TIMEOUT:
                raise errors.DatabaseTimeout()
            except ldap.LDAPError as e:
                desc = e.args[0]['desc'].strip()
                info = e.args[0].get('info', '').strip()
                if arg_desc is not None:
                    info = "%s arguments: %s" % (info, arg_desc)
                raise
        except ldap.NO_SUCH_OBJECT:
            raise errors.NotFound(reason=arg_desc or 'no such entry')
        except ldap.ALREADY_EXISTS:
            raise errors.DuplicateEntry()
        except ldap.CONSTRAINT_VIOLATION:
            # This error gets thrown by the uniqueness plugin
            _msg = 'Another entry with the same attribute value already exists'
            if info.startswith(_msg):
                raise errors.DuplicateEntry()
            else:
                raise errors.DatabaseError(desc=desc, info=info)
        except ldap.INSUFFICIENT_ACCESS:
            raise errors.ACIError(info=info)
        except ldap.INVALID_CREDENTIALS:
            raise errors.ACIError(info="%s %s" % (info, desc))
        except ldap.INAPPROPRIATE_AUTH:
            raise errors.ACIError(info="%s: %s" % (desc, info))
        except ldap.NO_SUCH_ATTRIBUTE:
            # this is raised when a 'delete' attribute isn't found.
            # it indicates the previous attribute was removed by another
            # update, making the oldentry stale.
            raise errors.MidairCollision()
        except ldap.INVALID_SYNTAX:
            raise errors.InvalidSyntax(attr=info)
        except ldap.OBJECT_CLASS_VIOLATION:
            raise errors.ObjectclassViolation(info=info)
        except ldap.ADMINLIMIT_EXCEEDED:
            raise errors.LimitsExceeded()
        except ldap.SIZELIMIT_EXCEEDED:
            raise errors.LimitsExceeded()
        except ldap.TIMELIMIT_EXCEEDED:
            raise errors.LimitsExceeded()
        except ldap.NOT_ALLOWED_ON_RDN:
            raise errors.NotAllowedOnRDN(attr=info)
        except ldap.FILTER_ERROR:
            raise errors.BadSearchFilter(info=info)
        except ldap.NOT_ALLOWED_ON_NONLEAF:
            raise errors.NotAllowedOnNonLeaf()
        except ldap.SERVER_DOWN:
            raise errors.NetworkError(uri=self.ldap_uri,
                                      error=info)
        except ldap.LOCAL_ERROR:
            raise errors.ACIError(info=info)
        except ldap.SUCCESS:
            pass
        except ldap.CONNECT_ERROR:
            raise errors.DatabaseError(desc=desc, info=info)
        except ldap.UNWILLING_TO_PERFORM:
            raise errors.DatabaseError(desc=desc, info=info)
        except ldap.AUTH_UNKNOWN:
            raise errors.ACIError(info='%s (%s)' % (info,desc))
        except ldap.LDAPError as e:
            if 'NOT_ALLOWED_TO_DELEGATE' in info:
                raise errors.ACIError(
                    info="KDC returned NOT_ALLOWED_TO_DELEGATE")
            self.log.debug(
                'Unhandled LDAPError: %s: %s' % (type(e).__name__, str(e)))
            raise errors.DatabaseError(desc=desc, info=info)

    @property
    def schema(self):
        """schema associated with this LDAP server"""
        return self._get_schema()

    def get_allowed_attributes(self, objectclasses, raise_on_unknown=False):
        if self.schema is None:
            return None
        allowed_attributes = []
        for oc in objectclasses:
            obj = self.schema.get_obj(ldap.schema.ObjectClass, oc)
            if obj is not None:
                allowed_attributes += obj.must + obj.may
            elif raise_on_unknown:
                raise errors.NotFound(
                    reason=_('objectclass %s not found') % oc)
        return [unicode(a).lower() for a in list(set(allowed_attributes))]

    def __del__(self):
        self.close()

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.close()

    def close(self):
        """
        Close the connection.
        """
        if self._conn is not None:
            self._disconnect()

    def _connect(self):
        if self._conn is not None:
            raise errors.DatabaseError(
                desc="Can't connect to server", info="Already connected")

        with self.error_handler():
            # bypass ldap2's locking
            object.__setattr__(self, '_conn',
                               ldap.initialize(self.ldap_uri))

            if self._start_tls:
                self._conn.start_tls_s()

    def _disconnect(self):
        if self._conn is None:
            raise errors.DatabaseError(
                desc="Can't disconnect from server", info="Not connected")

        # bypass ldap2's locking
        object.__setattr__(self, '_conn', None)

    def simple_bind(self, bind_dn, bind_password, server_controls=None,
                    client_controls=None):
        """
        Perform simple bind operation.
        """
        with self.error_handler():
            self._flush_schema()
            if bind_dn is None:
                bind_dn = DN()
            assert isinstance(bind_dn, DN)
            bind_dn = str(bind_dn)
            bind_password = self.encode(bind_password)
            self._conn.simple_bind_s(
                bind_dn, bind_password, server_controls, client_controls)

    def external_bind(self, user_name, server_controls=None,
                      client_controls=None):
        """
        Perform SASL bind operation using the SASL EXTERNAL mechanism.
        """
        with self.error_handler():
            auth_tokens = ldap.sasl.external(user_name)
            self._flush_schema()
            self._conn.sasl_interactive_bind_s(
                '', auth_tokens, server_controls, client_controls)

    def gssapi_bind(self, server_controls=None, client_controls=None):
        """
        Perform SASL bind operation using the SASL GSSAPI mechanism.
        """
        with self.error_handler():
            auth_tokens = ldap.sasl.sasl({}, 'GSSAPI')
            self._flush_schema()
            self._conn.sasl_interactive_bind_s(
                '', auth_tokens, server_controls, client_controls)

    def unbind(self):
        """
        Perform unbind operation.
        """
        with self.error_handler():
            self._flush_schema()
            self._conn.unbind_s()

    def make_dn_from_attr(self, attr, value, parent_dn=None):
        """
        Make distinguished name from attribute.

        Keyword arguments:
        parent_dn -- DN of the parent entry (default '')
        """
        if parent_dn is None:
            parent_dn = DN()

        if isinstance(value, (list, tuple)):
            value = value[0]

        return DN((attr, value), parent_dn)

    def make_dn(self, entry_attrs, primary_key='cn', parent_dn=None):
        """
        Make distinguished name from entry attributes.

        Keyword arguments:
        primary_key -- attribute from which to make RDN (default 'cn')
        parent_dn -- DN of the parent entry (default '')
        """

        assert primary_key in entry_attrs
        assert isinstance(parent_dn, DN)

        return DN((primary_key, entry_attrs[primary_key]), parent_dn)

    def make_entry(self, _dn=None, _obj=None, **kwargs):
        return LDAPEntry(self, _dn, _obj, **kwargs)

    # generating filters for find_entry
    # some examples:
    # f1 = ldap2.make_filter_from_attr(u'firstName', u'Pavel')
    # f2 = ldap2.make_filter_from_attr(u'lastName', u'Zuna')
    # f = ldap2.combine_filters([f1, f2], ldap2.MATCH_ALL)
    # # f should be (&(firstName=Pavel)(lastName=Zuna))
    # # it should be equivalent to:
    # entry_attrs = {u'firstName': u'Pavel', u'lastName': u'Zuna'}
    # f = ldap2.make_filter(entry_attrs, rules=ldap2.MATCH_ALL)

    def combine_filters(self, filters, rules='|'):
        """
        Combine filters into one for ldap2.find_entries.

        Keyword arguments:
        rules -- see ldap2.make_filter
        """

        assert isinstance(filters, (list, tuple))

        filters = [f for f in filters if f]
        if filters and rules == self.MATCH_NONE:  # unary operator
            return '(%s%s)' % (self.MATCH_NONE,
                               self.combine_filters(filters, self.MATCH_ANY))

        if len(filters) > 1:
            flt = '(%s' % rules
        else:
            flt = ''
        for f in filters:
            if not f.startswith('('):
                f = '(%s)' % f
            flt = '%s%s' % (flt, f)
        if len(filters) > 1:
            flt = '%s)' % flt
        return flt

    def make_filter_from_attr(
            self, attr, value, rules='|', exact=True,
            leading_wildcard=True, trailing_wildcard=True):
        """
        Make filter for ldap2.find_entries from attribute.

        Keyword arguments:
        rules -- see ldap2.make_filter
        exact -- boolean, True - make filter as (attr=value)
                          False - make filter as (attr=*value*)
        leading_wildcard -- boolean:
            True - allow heading filter wildcard when exact=False
            False - forbid heading filter wildcard when exact=False
        trailing_wildcard -- boolean:
            True - allow trailing filter wildcard when exact=False
            False - forbid trailing filter wildcard when exact=False
        """
        if isinstance(value, (list, tuple)):
            if rules == self.MATCH_NONE:
                make_filter_rules = self.MATCH_ANY
            else:
                make_filter_rules = rules
            flts = [
                self.make_filter_from_attr(
                    attr, v, exact=exact,
                    leading_wildcard=leading_wildcard,
                    trailing_wildcard=trailing_wildcard)
                for v in value
            ]
            return self.combine_filters(flts, rules)
        elif value is not None:
            value = ldap.filter.escape_filter_chars(value_to_utf8(value))
            if not exact:
                template = '%s'
                if leading_wildcard:
                    template = '*' + template
                if trailing_wildcard:
                    template = template + '*'
                value = template % value
            if rules == self.MATCH_NONE:
                return '(!(%s=%s))' % (attr, value)
            return '(%s=%s)' % (attr, value)
        return ''

    def make_filter(
            self, entry_attrs, attrs_list=None, rules='|', exact=True,
            leading_wildcard=True, trailing_wildcard=True):
        """
        Make filter for ldap2.find_entries from entry attributes.

        Keyword arguments:
        attrs_list -- list of attributes to use, all if None (default None)
        rules -- specifies how to determine a match (default ldap2.MATCH_ANY)
        exact -- boolean, True - make filter as (attr=value)
                          False - make filter as (attr=*value*)
        leading_wildcard -- boolean:
            True - allow heading filter wildcard when exact=False
            False - forbid heading filter wildcard when exact=False
        trailing_wildcard -- boolean:
            True - allow trailing filter wildcard when exact=False
            False - forbid trailing filter wildcard when exact=False

        rules can be one of the following:
        ldap2.MATCH_NONE - match entries that do not match any attribute
        ldap2.MATCH_ALL - match entries that match all attributes
        ldap2.MATCH_ANY - match entries that match any of attribute
        """
        if rules == self.MATCH_NONE:
            make_filter_rules = self.MATCH_ANY
        else:
            make_filter_rules = rules
        flts = []
        if attrs_list is None:
            for (k, v) in entry_attrs.iteritems():
                flts.append(
                    self.make_filter_from_attr(
                        k, v, make_filter_rules, exact,
                        leading_wildcard, trailing_wildcard)
                )
        else:
            for a in attrs_list:
                value = entry_attrs.get(a, None)
                if value is not None:
                    flts.append(
                        self.make_filter_from_attr(
                            a, value, make_filter_rules, exact,
                            leading_wildcard, trailing_wildcard)
                    )
        return self.combine_filters(flts, rules)

    def get_entries(self, base_dn, scope=ldap.SCOPE_SUBTREE, filter=None,
                    attrs_list=None):
        """Return a list of matching entries.

        :raises: errors.LimitsExceeded if the list is truncated by the server
        :raises: errors.NotFound if result set is empty
                                 or base_dn doesn't exist

        :param base_dn: dn of the entry at which to start the search
        :param scope: search scope, see LDAP docs (default ldap2.SCOPE_SUBTREE)
        :param filter: LDAP filter to apply
        :param attrs_list: ist of attributes to return, all if None (default)

        Use the find_entries method for more options.
        """
        entries, truncated = self.find_entries(
            base_dn=base_dn, scope=scope, filter=filter, attrs_list=attrs_list)
        if truncated:
            raise errors.LimitsExceeded()
        return entries

    def find_entries(self, filter=None, attrs_list=None, base_dn=None,
                     scope=ldap.SCOPE_SUBTREE, time_limit=None,
                     size_limit=None, search_refs=False, paged_search=False):
        """
        Return a list of entries and indication of whether the results were
        truncated ([(dn, entry_attrs)], truncated) matching specified search
        parameters followed by truncated flag. If the truncated flag is True,
        search hit a server limit and its results are incomplete.

        Keyword arguments:
        attrs_list -- list of attributes to return, all if None (default None)
        base_dn -- dn of the entry at which to start the search (default '')
        scope -- search scope, see LDAP docs (default ldap2.SCOPE_SUBTREE)
        time_limit -- time limit in seconds (default unlimited)
        size_limit -- size (number of entries returned) limit
            (default unlimited)
        search_refs -- allow search references to be returned
            (default skips these entries)
        paged_search -- search using paged results control

        :raises: errors.NotFound if result set is empty
                                 or base_dn doesn't exist
        """
        if base_dn is None:
            base_dn = DN()
        assert isinstance(base_dn, DN)
        if not filter:
            filter = '(objectClass=*)'
        res = []
        truncated = False

        if time_limit is None or time_limit == 0:
            time_limit = -1.0
        if size_limit is None:
            size_limit = 0
        if not isinstance(size_limit, int):
            size_limit = int(size_limit)
        if not isinstance(time_limit, float):
            time_limit = float(time_limit)

        if attrs_list:
            attrs_list = [a.lower() for a in set(attrs_list)]

        sctrls = None
        cookie = ''
        page_size = (size_limit if size_limit > 0 else 2000) - 1
        if page_size == 0:
            paged_search = False

        # pass arguments to python-ldap
        with self.error_handler():
            filter = self.encode(filter)
            attrs_list = self.encode(attrs_list)

            while True:
                if paged_search:
                    sctrls = [SimplePagedResultsControl(0, page_size, cookie)]

                try:
                    id = self.conn.search_ext(
                        str(base_dn), scope, filter, attrs_list,
                        serverctrls=sctrls, timeout=time_limit,
                        sizelimit=size_limit
                    )
                    while True:
                        result = self.conn.result3(id, 0)
                        objtype, res_list, res_id, res_ctrls = result
                        res_list = self._convert_result(res_list)
                        if not res_list:
                            break
                        if (objtype == ldap.RES_SEARCH_ENTRY or
                                (search_refs and
                                    objtype == ldap.RES_SEARCH_REFERENCE)):
                            res.append(res_list[0])

                    if paged_search:
                        # Get cookie for the next page
                        for ctrl in res_ctrls:
                            if isinstance(ctrl, SimplePagedResultsControl):
                                cookie = ctrl.cookie
                                break
                        else:
                            cookie = ''
                except ldap.LDAPError as e:
                    # If paged search is in progress, try to cancel it
                    if paged_search and cookie:
                        sctrls = [SimplePagedResultsControl(0, 0, cookie)]
                        try:
                            self.conn.search_ext_s(
                                str(base_dn), scope, filter, attrs_list,
                                serverctrls=sctrls, timeout=time_limit,
                                sizelimit=size_limit)
                        except ldap.LDAPError as e:
                            self.log.warning(
                                "Error cancelling paged search: %s", e)
                        cookie = ''

                    try:
                        raise e
                    except (ldap.ADMINLIMIT_EXCEEDED, ldap.TIMELIMIT_EXCEEDED,
                            ldap.SIZELIMIT_EXCEEDED):
                        truncated = True
                        break

                if not paged_search or not cookie:
                    break

        if not res and not truncated:
            raise errors.EmptyResult(reason='no matching entry found')

        return (res, truncated)

    def find_entry_by_attr(self, attr, value, object_class, attrs_list=None,
                           base_dn=None):
        """
        Find entry (dn, entry_attrs) by attribute and object class.

        Keyword arguments:
        attrs_list - list of attributes to return, all if None (default None)
        base_dn - dn of the entry at which to start the search (default '')
        """

        if base_dn is None:
            base_dn = DN()
        assert isinstance(base_dn, DN)

        search_kw = {attr: value, 'objectClass': object_class}
        filter = self.make_filter(search_kw, rules=self.MATCH_ALL)
        (entries, truncated) = self.find_entries(filter, attrs_list, base_dn)

        if len(entries) > 1:
            raise errors.SingleMatchExpected(found=len(entries))
        else:
            if truncated:
                raise errors.LimitsExceeded()
            else:
                return entries[0]

    def get_entry(self, dn, attrs_list=None, time_limit=None,
                  size_limit=None):
        """
        Get entry (dn, entry_attrs) by dn.

        Keyword arguments:
        attrs_list - list of attributes to return, all if None (default None)
        """

        assert isinstance(dn, DN)

        (entries, truncated) = self.find_entries(
            None, attrs_list, dn, self.SCOPE_BASE, time_limit=time_limit,
            size_limit=size_limit
        )

        if truncated:
            raise errors.LimitsExceeded()
        return entries[0]

    def add_entry(self, entry):
        """Create a new entry.

        This should be called as add_entry(entry).
        """
        # remove all [] values (python-ldap hates 'em)
        attrs = dict((k, v) for k, v in entry.raw.iteritems() if v)

        with self.error_handler():
            attrs = self.encode(attrs)
            self.conn.add_s(str(entry.dn), attrs.items())

        entry.reset_modlist()

    def move_entry(self, dn, new_dn, del_old=True):
        """
        Move an entry (either to a new superior or/and changing relative distinguished name)

        Keyword arguments:
        dn: DN of the source entry
        new_dn: DN of the target entry
        del_old -- delete old RDN value (default True)

        :raises:
        errors.NotFound if source entry or target superior entry doesn't exist
        errors.EmptyModlist if source and target are identical
        """
        assert isinstance(dn, DN)
        assert isinstance(new_dn, DN)

        if new_dn == dn:
            raise errors.EmptyModlist()

        new_rdn = new_dn[0]

        if new_dn[1:] == dn[1:]:
            new_superior = None
        else:
            new_superior = str(DN(*new_dn[1:]))

        with self.error_handler():
            self.conn.rename_s(str(dn), str(new_rdn), newsuperior=new_superior,
                               delold=int(del_old))
            time.sleep(.3)  # Give memberOf plugin a chance to work

    def update_entry(self, entry):
        """Update entry's attributes.

        This should be called as update_entry(entry).
        """
        # generate modlist
        modlist = entry.generate_modlist()
        if not modlist:
            raise errors.EmptyModlist()

        # pass arguments to python-ldap
        with self.error_handler():
            modlist = [(a, self.encode(b), self.encode(c))
                       for a, b, c in modlist]
            self.conn.modify_s(str(entry.dn), modlist)

        entry.reset_modlist()

    def delete_entry(self, entry_or_dn):
        """Delete an entry given either the DN or the entry itself"""
        if isinstance(entry_or_dn, DN):
            dn = entry_or_dn
        else:
            dn = entry_or_dn.dn

        with self.error_handler():
            self.conn.delete_s(str(dn))

    def entry_exists(self, dn):
        """
        Test whether the given object exists in LDAP.
        """
        assert isinstance(dn, DN)
        try:
            self.get_entry(dn, attrs_list=[])
        except errors.NotFound:
            return False
        else:
            return True


class IPAdmin(LDAPClient):

    def __get_ldap_uri(self, protocol):
        if protocol == 'ldaps':
            return 'ldaps://%s' % format_netloc(self.host, self.port)
        elif protocol == 'ldapi':
            return 'ldapi://%%2fvar%%2frun%%2fslapd-%s.socket' % (
                "-".join(self.realm.split(".")))
        elif protocol == 'ldap':
            return 'ldap://%s' % format_netloc(self.host, self.port)
        else:
            raise ValueError('Protocol %r not supported' % protocol)


    def __guess_protocol(self):
        """Return the protocol to use based on flags passed to the constructor

        Only used when "protocol" is not specified explicitly.

        If a CA certificate is provided then it is assumed that we are
        doing SSL client authentication with proxy auth.

        If a CA certificate is not present then it is assumed that we are
        using a forwarded kerberos ticket for SASL auth. SASL provides
        its own encryption.
        """
        if self.cacert is not None:
            return 'ldaps'
        elif self.ldapi:
            return 'ldapi'
        else:
            return 'ldap'

    def __init__(self, host='', port=389, cacert=None, debug=None, ldapi=False,
                 realm=None, protocol=None, force_schema_updates=True,
                 start_tls=False, ldap_uri=None, no_schema=False,
                 decode_attrs=True, sasl_nocanon=False, demand_cert=False):
        self._conn = None
        log_mgr.get_logger(self, True)
        if debug and debug.lower() == "on":
            ldap.set_option(ldap.OPT_DEBUG_LEVEL,255)
        if cacert is not None:
            ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, cacert)

        self.port = port
        self.host = host
        self.cacert = cacert
        self.ldapi = ldapi
        self.realm = realm
        self.suffixes = {}

        if not ldap_uri:
            ldap_uri = self.__get_ldap_uri(protocol or self.__guess_protocol())

        super(IPAdmin, self).__init__(
            ldap_uri, force_schema_updates=force_schema_updates,
            no_schema=no_schema, decode_attrs=decode_attrs)

        with self.error_handler():
            if demand_cert:
                ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, True)
                self.conn.set_option(ldap.OPT_X_TLS_DEMAND, True)

            if sasl_nocanon:
                self.conn.set_option(ldap.OPT_X_SASL_NOCANON, ldap.OPT_ON)

            if start_tls:
                self.conn.start_tls_s()

    def __str__(self):
        return self.host + ":" + str(self.port)

    def __wait_for_connection(self, timeout):
        lurl = ldapurl.LDAPUrl(self.ldap_uri)
        if lurl.urlscheme == 'ldapi':
            wait_for_open_socket(lurl.hostport, timeout)
        else:
            (host,port) = lurl.hostport.split(':')
            wait_for_open_ports(host, int(port), timeout)

    def __bind_with_wait(self, bind_func, timeout, *args, **kwargs):
        try:
            bind_func(*args, **kwargs)
        except errors.NetworkError as e:
            if not timeout and 'TLS' in e.error:
                # No connection to continue on if we have a TLS failure
                # https://bugzilla.redhat.com/show_bug.cgi?id=784989
                raise
        except errors.DatabaseError:
            pass
        else:
            return
        self.__wait_for_connection(timeout)
        bind_func(*args, **kwargs)

    def do_simple_bind(self, binddn=DN(('cn', 'directory manager')), bindpw="",
                       timeout=DEFAULT_TIMEOUT):
        self.__bind_with_wait(self.simple_bind, timeout, binddn, bindpw)

    def do_sasl_gssapi_bind(self, timeout=DEFAULT_TIMEOUT):
        self.__bind_with_wait(self.gssapi_bind, timeout)

    def do_external_bind(self, user_name=None, timeout=DEFAULT_TIMEOUT):
        self.__bind_with_wait(self.external_bind, timeout, user_name)

    def do_bind(self, dm_password="", autobind=AUTOBIND_AUTO, timeout=DEFAULT_TIMEOUT):
        if dm_password:
            self.do_simple_bind(bindpw=dm_password, timeout=timeout)
            return
        if autobind != AUTOBIND_DISABLED and os.getegid() == 0 and self.ldapi:
            try:
                # autobind
                pw_name = pwd.getpwuid(os.geteuid()).pw_name
                self.do_external_bind(pw_name, timeout=timeout)
                return
            except errors.NotFound as e:
                if autobind == AUTOBIND_ENABLED:
                    # autobind was required and failed, raise
                    # exception that it failed
                    raise

        #fall back
        self.do_sasl_gssapi_bind(timeout=timeout)

    def modify_s(self, dn, modlist):
        # FIXME: for backwards compatibility only
        assert isinstance(dn, DN)
        dn = str(dn)
        modlist = [(a, self.encode(b), self.encode(c)) for a, b, c in modlist]
        return self.conn.modify_s(dn, modlist)