summaryrefslogtreecommitdiffstats
path: root/ipaserver/plugins/ldap2.py
blob: 6f34984caf85fce7a8174bad10255299a45fc5d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
# Authors:
#   Pavel Zuna <pzuna@redhat.com>
#
# Copyright (C) 2009  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/>.
"""
Backend plugin for LDAP.
"""

# Entries are represented as (dn, entry_attrs), where entry_attrs is a dict
# mapping attribute names to values. Values can be a single value or list/tuple
# of virtually any type. Each method passing these values to the python-ldap
# binding encodes them into the appropriate representation. This applies to
# everything except the CrudBackend methods, where dn is part of the entry dict.

import copy
import os
import socket
import string
import shutil
import tempfile
import time

import krbV
import logging
import ldap as _ldap
import ldap.filter as _ldap_filter
import ldap.sasl as _ldap_sasl
from ldap.controls import LDAPControl
# for backward compatibility
from ldap.functions import explode_dn

import krbV

from ipalib import api, errors
from ipalib.crud import CrudBackend
from ipalib.encoder import Encoder, encode_args, decode_retval
from ipalib.request import context


# Group Member types
MEMBERS_ALL = 0
MEMBERS_DIRECT = 1
MEMBERS_INDIRECT = 2

# SASL authentication mechanism
SASL_AUTH = _ldap_sasl.sasl({}, 'GSSAPI')

# universal LDAPError handler
def _handle_errors(e, **kw):
    """
    Centralize error handling in one place.

    e is the error to be raised
    **kw is an exception-specific list of options
    """
    if not isinstance(e, _ldap.TIMEOUT):
        desc = e.args[0]['desc'].strip()
        info = e.args[0].get('info', '').strip()
    else:
        desc = ''
        info = ''

    try:
        # re-raise the error so we can handle it
        raise e
    except _ldap.NO_SUCH_OBJECT:
        # args = kw.get('args', '')
        # raise errors.NotFound(msg=notfound(args))
        raise errors.NotFound(reason='no such entry')
    except _ldap.ALREADY_EXISTS:
        raise errors.DuplicateEntry()
    except _ldap.CONSTRAINT_VIOLATION:
        # This error gets thrown by the uniqueness plugin
        if info == 'Another entry with the same attribute value already exists':
            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.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.SUCCESS:
        pass
    except _ldap.LDAPError, e:
        raise errors.DatabaseError(desc=desc, info=info)


def get_schema(url, conn=None):
    """
    Perform global initialization when the module is loaded.

    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
    has_conn = conn is not None

    if ((not api.env.in_server or api.env.context not in ['lite', 'server'])
        and conn is None):
        # The schema is only needed on the server side
        return None

    try:
        if api.env.context == 'server' and conn is None:
            try:
                # Create a new credentials cache for this Apache process
                tmpdir = tempfile.mkdtemp(prefix = "tmp-")
                ccache_file = 'FILE:%s/ccache' % tmpdir
                krbcontext = krbV.default_context()
                principal = str('HTTP/%s@%s' % (api.env.host, api.env.realm))
                keytab = krbV.Keytab(name='/etc/httpd/conf/ipa.keytab', context=krbcontext)
                principal = krbV.Principal(name=principal, context=krbcontext)
                os.environ['KRB5CCNAME'] = ccache_file
                ccache = krbV.CCache(name=ccache_file, context=krbcontext, primary_principal=principal)
                ccache.init(principal)
                ccache.init_creds_keytab(keytab=keytab, principal=principal)
            except krbV.Krb5Error, e:
                raise StandardError('Unable to retrieve LDAP schema. Error initializing principal %s in %s: %s' % (principal.name, '/etc/httpd/conf/ipa.keytab', str(e)))

        if conn is None:
            conn = _ldap.initialize(url)
            if url.startswith('ldapi://'):
                conn.set_option(_ldap.OPT_HOST_NAME, api.env.host)
            conn.sasl_interactive_bind_s('', SASL_AUTH)

        schema_entry = conn.search_s(
            'cn=schema', _ldap.SCOPE_BASE,
            attrlist=['attributetypes', 'objectclasses']
        )[0]
        if not has_conn:
            conn.unbind_s()
    except _ldap.SERVER_DOWN:
        return None
    except _ldap.LDAPError, e:
        desc = e.args[0]['desc'].strip()
        info = e.args[0].get('info', '').strip()
        raise StandardError('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])

# Global schema
_schema = None

# The UPG setting will be cached the first time a module checks it
_upg = None

class ldap2(CrudBackend, Encoder):
    """
    LDAP Backend Take 2.
    """
    # attribute syntax to python type mapping, 'SYNTAX OID': type
    # everything not in this dict is considered human readable unicode
    _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
        '1.3.6.1.4.1.1466.115.121.1.23': str, # Fax
        '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
    }

    # attributes in this list cannot be deleted by update_entry
    # only MOD_REPLACE operations are generated for them
    _FORCE_REPLACE_ON_UPDATE_ATTRS = []

    # 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

    def __init__(self, shared_instance=True, ldap_uri=None, base_dn=None,
                 schema=None):
        global _schema
        CrudBackend.__init__(self, shared_instance=shared_instance)
        Encoder.__init__(self)
        self.encoder_settings.encode_dict_keys = True
        self.encoder_settings.decode_dict_keys = True
        self.encoder_settings.decode_dict_vals_postprocess = False
        self.encoder_settings.decode_dict_vals_table = self._SYNTAX_MAPPING
        self.encoder_settings.decode_dict_vals_table_keygen = self.get_syntax
        self.encoder_settings.decode_postprocessor = lambda x: string.lower(x)
        try:
            self.ldap_uri = ldap_uri or api.env.ldap_uri
        except AttributeError:
            self.ldap_uri = 'ldap://example.com'
        try:
            if base_dn is not None:
                self.base_dn = base_dn
            else:
                self.base_dn = api.env.basedn
        except AttributeError:
            self.base_dn = ''
        self.schema = schema or _schema

    def __del__(self):
        if self.isconnected():
            self.disconnect()

    def __str__(self):
        return self.ldap_uri

    def get_syntax(self, attr, value):
        if not self.schema:
            self.get_schema()
        obj = self.schema.get_obj(_ldap.schema.AttributeType, attr)
        if obj is not None:
            return obj.syntax
        else:
            return None

    def get_allowed_attributes(self, objectclasses):
        if not self.schema:
            self.get_schema()
        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
        return [unicode(a).lower() for a in list(set(allowed_attributes))]

    def get_single_value(self, attr):
        """
        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 not self.schema:
            self.get_schema()
        obj = self.schema.get_obj(_ldap.schema.AttributeType, attr)
        return obj and obj.single_value

    @encode_args(2, 3, 'bind_dn', 'bind_pw')
    def create_connection(self, ccache=None, bind_dn='', bind_pw='',
            tls_cacertfile=None, tls_certfile=None, tls_keyfile=None,
            debug_level=0):
        """
        Connect to LDAP server.

        Keyword arguments:
        ldapuri -- the LDAP server to connect to
        ccache -- Kerberos V5 ccache name
        bind_dn -- dn used to bind to the server
        bind_pw -- password used to bind to the server
        debug_level -- LDAP debug level option
        tls_cacertfile -- TLS CA certificate filename
        tls_certfile -- TLS certificate filename
        tls_keyfile - TLS bind key filename

        Extends backend.Connectible.create_connection.
        """
        global _schema
        if tls_cacertfile is not None:
            _ldap.set_option(_ldap.OPT_X_TLS_CACERTFILE, tls_cacertfile)
        if tls_certfile is not None:
            _ldap.set_option(_ldap.OPT_X_TLS_CERTFILE, tls_certfile)
        if tls_keyfile is not None:
            _ldap.set_option(_ldap.OPT_X_TLS_KEYFILE, tls_keyfile)

        if debug_level:
            _ldap.set_option(_ldap.OPT_DEBUG_LEVEL, debug_level)

        try:
            conn = _ldap.initialize(self.ldap_uri)
            if self.ldap_uri.startswith('ldapi://'):
                conn.set_option(_ldap.OPT_HOST_NAME, api.env.host)
            if ccache is not None:
                os.environ['KRB5CCNAME'] = ccache
                conn.sasl_interactive_bind_s('', SASL_AUTH)
                principal = krbV.CCache(name=ccache,
                            context=krbV.default_context()).principal().name
                setattr(context, 'principal', principal)
            else:
                # no kerberos ccache, use simple bind
                conn.simple_bind_s(bind_dn, bind_pw)
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

        if _schema:
            object.__setattr__(self, 'schema', _schema)
        return conn

    def destroy_connection(self):
        """Disconnect from LDAP server."""
        try:
            self.conn.unbind_s()
        except _ldap.LDAPError:
            # ignore when trying to unbind multiple times
            pass

    def normalize_dn(self, dn):
        """
        Normalize distinguished name.

        Note: You don't have to normalize DN's before passing them to
              ldap2 methods. It's done internally for you.
        """
        rdns = explode_dn(dn)
        if rdns:
            dn = ','.join(rdns)
            if not dn.endswith(self.base_dn):
                dn = '%s,%s' % (dn, self.base_dn)
            return dn
        return self.base_dn

    def get_container_rdn(self, name):
        """Get relative distinguished name of cotainer."""
        env_container = 'container_%s' % name
        if env_container in self.api.env:
            return self.api.env[env_container]
        return ''

    def make_rdn_from_attr(self, attr, value):
        """Make relative distinguished name from attribute."""
        if isinstance(value, (list, tuple)):
            value = value[0]
        attr = _ldap.dn.escape_dn_chars(attr)
        value = _ldap.dn.escape_dn_chars(value)
        return '%s=%s' % (attr, value)

    def make_dn_from_rdn(self, rdn, parent_dn=''):
        """
        Make distinguished name from relative distinguished name.

        Keyword arguments:
        parent_dn -- DN of the parent entry (default '')
        """
        parent_dn = self.normalize_dn(parent_dn)
        return '%s,%s' % (rdn, parent_dn)

    def make_dn_from_attr(self, attr, value, parent_dn=''):
        """
        Make distinguished name from attribute.

        Keyword arguments:
        parent_dn -- DN of the parent entry (default '')
        """
        rdn = self.make_rdn_from_attr(attr, value)
        return self.make_dn_from_rdn(rdn, parent_dn)

    def make_dn(self, entry_attrs, primary_key='cn', parent_dn=''):
        """
        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
        rdn = self.make_rdn_from_attr(primary_key, entry_attrs[primary_key])
        return self.make_dn_from_rdn(rdn, parent_dn)

    @encode_args(1, 2)
    def add_entry(self, dn, entry_attrs, normalize=True):
        """Create a new entry."""
        if normalize:
            dn = self.normalize_dn(dn)
        # remove all None values, python-ldap hates'em
        entry_attrs = dict(
            (k, v) for (k, v) in entry_attrs.iteritems() if v
        )
        try:
            self.conn.add_s(dn, list(entry_attrs.iteritems()))
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

    # 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 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

    @encode_args(1, 2)
    def make_filter_from_attr(self, attr, value, rules='|', exact=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*)
        """
        if isinstance(value, (list, tuple)):
            flts = []
            if rules == self.MATCH_NONE:
                for v in value:
                    flts.append(
                        self.make_filter_from_attr(attr, v, exact=exact)
                    )
                return '(!%s)' % self.combine_filters(flts)
            for v in value:
                flts.append(self.make_filter_from_attr(attr, v, rules, exact))
            return self.combine_filters(flts, rules)
        elif value is not None:
            value = _ldap_filter.escape_filter_chars(value)
            if not exact:
                value = '*%s*' % 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):
        """
        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*)

        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
        """
        flts = []
        if attrs_list is None:
            for (k, v) in entry_attrs.iteritems():
                flts.append(
                    self.make_filter_from_attr(k, v, rules, exact)
                )
        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, rules, exact)
                    )
        return self.combine_filters(flts, rules)

    @encode_args(1, 2, 3)
    @decode_retval()
    def find_entries(self, filter=None, attrs_list=None, base_dn='',
            scope=_ldap.SCOPE_SUBTREE, time_limit=None, size_limit=None,
            normalize=True, search_refs=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 use IPA config values)
        size_limit -- size (number of entries returned) limit (default use IPA config values)
        normalize -- normalize the DN (default True)
        search_refs -- allow search references to be returned (default skips these entries)
        """
        if normalize:
            base_dn = self.normalize_dn(base_dn)
        if not filter:
            filter = '(objectClass=*)'
        res = []
        truncated = False

        if time_limit is None or size_limit is None:
            (cdn, config) = self.get_ipa_config()
            if time_limit is None:
                time_limit = config.get('ipasearchtimelimit', [-1])[0]
            if size_limit is None:
                size_limit = config.get('ipasearchrecordslimit', [0])[0]
        if time_limit == 0:
            time_limit = -1
        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 = list(set(attrs_list))

        # pass arguments to python-ldap
        try:
            id = self.conn.search_ext(
                base_dn, scope, filter, attrs_list, timeout=time_limit,
                sizelimit=size_limit
            )
            while True:
                (objtype, res_list) = self.conn.result(id, 0)
                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])
        except (_ldap.ADMINLIMIT_EXCEEDED, _ldap.TIMELIMIT_EXCEEDED,
                _ldap.SIZELIMIT_EXCEEDED), e:
            truncated = True
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

        if not res:
            raise errors.NotFound(reason='no such entry')

        if attrs_list and ('memberindirect' in attrs_list or '*' in attrs_list):
            for r in res:
                if not 'member' in r[1]:
                    continue
                else:
                    members = r[1]['member']
                    indirect = self.get_members(r[0], members, membertype=MEMBERS_INDIRECT,
                        time_limit=time_limit, size_limit=size_limit, normalize=normalize)
                    if len(indirect) > 0:
                        r[1]['memberindirect'] = indirect
        if attrs_list and ('memberofindirect' in attrs_list or '*' in attrs_list):
            for r in res:
                if 'memberof' in r[1]:
                    memberof = r[1]['memberof']
                    del r[1]['memberof']
                elif 'memberOf' in r[1]:
                    memberof = r[1]['memberOf']
                    del r[1]['memberOf']
                else:
                    continue
                (direct, indirect) = self.get_memberof(r[0], memberof, time_limit=time_limit, size_limit=size_limit, normalize=normalize)
                if len(direct) > 0:
                    r[1]['memberof'] = direct
                if len(indirect) > 0:
                    r[1]['memberofindirect'] = indirect

        return (res, truncated)

    def find_entry_by_attr(self, attr, value, object_class, attrs_list=None,
            base_dn=''):
        """
        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 '')
        """
        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:
            return entries[0]

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

        Keyword arguments:
        attrs_list - list of attributes to return, all if None (default None)
        """
        return self.find_entries(
            None, attrs_list, dn, self.SCOPE_BASE, time_limit=time_limit,
            size_limit=size_limit, normalize=normalize
        )[0][0]

    config_defaults = {'ipasearchtimelimit': [2], 'ipasearchrecordslimit': [0]}
    def get_ipa_config(self, attrs_list=None):
        """Returns the IPA configuration entry (dn, entry_attrs)."""
        cdn = "%s,%s" % (api.Object.config.get_dn(), api.env.basedn)
        try:
            config_entry = getattr(context, 'config_entry')
            return (cdn, copy.deepcopy(config_entry))
        except AttributeError:
            # Not in our context yet
            pass
        try:
            (cdn, config_entry) = self.find_entries(
                None, attrs_list, base_dn=cdn, scope=self.SCOPE_BASE,
                time_limit=2, size_limit=10
            )[0][0]
        except errors.NotFound:
            config_entry = {}
        for a in self.config_defaults:
            if a not in config_entry:
                config_entry[a] = self.config_defaults[a]
        setattr(context, 'config_entry', copy.deepcopy(config_entry))
        return (cdn, config_entry)

    def get_schema(self, deepcopy=False):
        """Returns either a reference to current schema or its deep copy"""
        global _schema
        if not _schema:
            _schema = get_schema(self.ldap_uri, self.conn)
            if not _schema:
                raise errors.DatabaseError(desc='Unable to retrieve LDAP schema', info='Unable to proceed with request')
            # explicitly use setattr here so the schema can be set after
            # the object is finalized.
            object.__setattr__(self, 'schema', _schema)

        if (deepcopy):
            return copy.deepcopy(self.schema)
        else:
            return self.schema

    def has_upg(self):
        """Returns True/False whether User-Private Groups are enabled.
           This is determined based on whether the UPG Template exists.
           We determine this at module load so we don't have to test for
           it every time.
        """
        global _upg

        if _upg is None:
            try:
                upg_entry = self.conn.search_s(
                    'cn=UPG Template,cn=etc,%s' % api.env.basedn,
                    _ldap.SCOPE_BASE,
                    attrlist=['*']
                )[0]
                _upg = True
            except _ldap.NO_SUCH_OBJECT, e:
                _upg = False

        return _upg

    @encode_args(1, 2)
    def get_effective_rights(self, dn, entry_attrs):
        """Returns the rights the currently bound user has for the given DN.

           Returns 2 attributes, the attributeLevelRights for the given list of
           attributes and the entryLevelRights for the entry itself.
        """
        principal = getattr(context, 'principal')
        (binddn, attrs) = self.find_entry_by_attr("krbprincipalname", principal, "krbPrincipalAux")
        sctrl = [LDAPControl("1.3.6.1.4.1.42.2.27.9.5.2", True, "dn: " + binddn.encode('UTF-8'))]
        self.conn.set_option(_ldap.OPT_SERVER_CONTROLS, sctrl)
        (dn, attrs) = self.get_entry(dn, entry_attrs)
        # remove the control so subsequent operations don't include GER
        self.conn.set_option(_ldap.OPT_SERVER_CONTROLS, [])
        return (dn, attrs)

    @encode_args(1, 2)
    def can_write(self, dn, attr):
        """Returns True/False if the currently bound user has write permissions
           on the attribute. This only operates on a single attribute at a time.
        """
        (dn, attrs) = self.get_effective_rights(dn, [attr])
        if 'attributelevelrights' in attrs:
            attr_rights = attrs.get('attributelevelrights')[0].decode('UTF-8')
            (attr, rights) = attr_rights.split(':')
            if 'w' in rights:
                return True

        return False

    @encode_args(1, 2)
    def can_read(self, dn, attr):
        """Returns True/False if the currently bound user has read permissions
           on the attribute. This only operates on a single attribute at a time.
        """
        (dn, attrs) = self.get_effective_rights(dn, [attr])
        if 'attributelevelrights' in attrs:
            attr_rights = attrs.get('attributelevelrights')[0].decode('UTF-8')
            (attr, rights) = attr_rights.split(':')
            if 'r' in rights:
                return True

        return False

    #
    # Entry-level effective rights
    #
    # a - Add
    # d - Delete
    # n - Rename the DN
    # v - View the entry
    #

    @encode_args(1)
    def can_delete(self, dn):
        """Returns True/False if the currently bound user has delete permissions
           on the entry.
        """
        (dn, attrs) = self.get_effective_rights(dn, ["*"])
        if 'entrylevelrights' in attrs:
            entry_rights = attrs['entrylevelrights'][0].decode('UTF-8')
            if 'd' in entry_rights:
                return True

        return False

    @encode_args(1)
    def can_add(self, dn):
        """Returns True/False if the currently bound user has add permissions
           on the entry.
        """
        (dn, attrs) = self.get_effective_rights(dn, ["*"])
        if 'entrylevelrights' in attrs:
            entry_rights = attrs['entrylevelrights'][0].decode('UTF-8')
            if 'a' in entry_rights:
                return True

        return False

    @encode_args(1, 2)
    def update_entry_rdn(self, dn, new_rdn, del_old=True):
        """
        Update entry's relative distinguished name.

        Keyword arguments:
        del_old -- delete old RDN value (default True)
        """
        dn = self.normalize_dn(dn)
        if dn.startswith(new_rdn + ","):
            raise errors.EmptyModlist()
        try:
            self.conn.rename_s(dn, new_rdn, delold=int(del_old))
            time.sleep(.3) # Give memberOf plugin a chance to work
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

    def _generate_modlist(self, dn, entry_attrs, normalize):
        # get original entry
        (dn, entry_attrs_old) = self.get_entry(dn, entry_attrs.keys(), normalize=normalize)
        # get_entry returns a decoded entry, encode it back
        # we could call search_s directly, but this saves a lot of code at
        # the expense of a little bit of performace
        entry_attrs_old = self.encode(entry_attrs_old)
        # generate modlist
        # for multi value attributes: no MOD_REPLACE to handle simultaneous
        # updates better
        # for single value attribute: always MOD_REPLACE
        modlist = []
        for (k, v) in entry_attrs.iteritems():
            if v is None and k in entry_attrs_old:
                modlist.append((_ldap.MOD_DELETE, k, None))
            else:
                if not isinstance(v, (list, tuple)):
                    v = [v]
                v = set(filter(lambda value: value is not None, v))
                old_v = set(entry_attrs_old.get(k.lower(), []))

                adds = list(v.difference(old_v))
                rems = list(old_v.difference(v))

                is_single_value = self.get_single_value(k)

                value_count = len(old_v) + len(adds) - len(rems)
                if is_single_value and value_count > 1:
                    raise errors.OnlyOneValueAllowed(attr=k)

                force_replace = False
                if k in self._FORCE_REPLACE_ON_UPDATE_ATTRS or is_single_value:
                    force_replace = True
                elif len(v) > 0 and len(v.intersection(old_v)) == 0:
                    force_replace = True

                if adds:
                    if force_replace:
                        modlist.append((_ldap.MOD_REPLACE, k, adds))
                    else:
                        modlist.append((_ldap.MOD_ADD, k, adds))
                if rems:
                    if not force_replace:
                        modlist.append((_ldap.MOD_DELETE, k, rems))

        return modlist

    @encode_args(1, 2)
    def update_entry(self, dn, entry_attrs, normalize=True):
        """
        Update entry's attributes.

        An attribute value set to None deletes all current values.
        """
        if normalize:
            dn = self.normalize_dn(dn)

        # generate modlist
        modlist = self._generate_modlist(dn, entry_attrs, normalize)
        if not modlist:
            raise errors.EmptyModlist()

        # pass arguments to python-ldap
        try:
            self.conn.modify_s(dn, modlist)
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

    @encode_args(1)
    def delete_entry(self, dn, normalize=True):
        """Delete entry."""
        if normalize:
            dn = self.normalize_dn(dn)
        try:
            self.conn.delete_s(dn)
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

    @encode_args(1, 2, 3)
    def modify_password(self, dn, new_pass, old_pass=''):
        """Set user password."""
        dn = self.normalize_dn(dn)
        try:
            self.conn.passwd_s(dn, old_pass, new_pass)
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

    def add_entry_to_group(self, dn, group_dn, member_attr='member', allow_same=False):
        """
        Add entry designaed by dn to group group_dn in the member attribute
        member_attr.

        Adding a group as a member of itself is not allowed unless allow_same
        is True.
        """
        # check if the entry exists
        (dn, entry_attrs) = self.get_entry(dn, ['objectclass'])

        # get group entry
        (group_dn, group_entry_attrs) = self.get_entry(group_dn, [member_attr])

        # check if we're not trying to add group into itself
        if dn == group_dn and not allow_same:
            raise errors.SameGroupError()

        # add dn to group entry's `member_attr` attribute
        members = group_entry_attrs.get(member_attr, [])
        members.append(dn)
        group_entry_attrs[member_attr] = members

        # update group entry
        try:
            self.update_entry(group_dn, group_entry_attrs)
        except errors.EmptyModlist:
            raise errors.AlreadyGroupMember()

    def remove_entry_from_group(self, dn, group_dn, member_attr='member'):
        """Remove entry from group."""
        # get group entry
        (group_dn, group_entry_attrs) = self.get_entry(group_dn, [member_attr])

        # remove dn from group entry's `member_attr` attribute
        members = group_entry_attrs.get(member_attr, [])
        try:
            members.remove(dn.lower())
        except ValueError:
            raise errors.NotGroupMember()
        group_entry_attrs[member_attr] = members

        # update group entry
        self.update_entry(group_dn, group_entry_attrs)

    def get_members(self, group_dn, members, attr_list=[], membertype=MEMBERS_ALL, time_limit=None, size_limit=None, normalize=True):
        """Do a memberOf search of groupdn and return the attributes in
           attr_list (an empty list returns all attributes).

           membertype = MEMBERS_ALL all members returned
           membertype = MEMBERS_DIRECT only direct members are returned
           membertype = MEMBERS_INDIRECT only inherited members are returned

           Members may be included in a group as a result of being a member
           of a group that is a member of the group being queried.

           Returns a list of DNs.
        """
        if membertype not in [MEMBERS_ALL, MEMBERS_DIRECT, MEMBERS_INDIRECT]:
            return None

        search_group_dn = _ldap_filter.escape_filter_chars(group_dn)
        searchfilter = "(memberof=%s)" % search_group_dn

        attr_list.append("member")

        # Verify group membership

        results = []
        if membertype == MEMBERS_ALL or membertype == MEMBERS_INDIRECT:
            checkmembers = copy.deepcopy(members)
            for member in checkmembers:
                try:
                    (result, truncated) = self.find_entries(searchfilter,
                        attr_list, member, time_limit=time_limit,
                        size_limit=size_limit, normalize=normalize)
                    results.append(list(result[0]))
                    for m in result[0][1].get('member', []):
                        # This member may contain other members, add it to our
                        # candidate list
                        if m not in checkmembers:
                            checkmembers.append(m)
                except errors.NotFound:
                    pass

        if membertype == MEMBERS_ALL:
            entries = []
            for e in results:
                entries.append(e[0])

            return entries

        (dn, group) = self.get_entry(group_dn, ['dn', 'member'],
            size_limit=size_limit, time_limit=time_limit)
        real_members = group.get('member')
        if isinstance(real_members, basestring):
            real_members = [real_members]
        if real_members is None:
            real_members = []

        entries = []
        for e in results:
            if unicode(e[0]) not in real_members and unicode(e[0]) not in entries:
                if membertype == MEMBERS_INDIRECT:
                    entries.append(e[0])
            else:
                if membertype == MEMBERS_DIRECT:
                    entries.append(e[0])

        return entries

    def get_memberof(self, entry_dn, memberof, time_limit=None, size_limit=None, normalize=True):
        """
        Examine the objects that an entry is a member of and determine if they
        are a direct or indirect member of that group.

        entry_dn: dn of the entry we want the direct/indirect members of
        memberof: the memberOf attribute for entry_dn

        Returns two memberof lists: (direct, indirect)
        """

        if not type(memberof) in (list, tuple):
            return ([], [])
        if len(memberof) == 0:
            return ([], [])

        search_entry_dn = _ldap_filter.escape_filter_chars(entry_dn)
        attr_list = ["dn", "memberof"]
        searchfilter = "(|(member=%s)(memberhost=%s)(memberuser=%s))" % (
            search_entry_dn, search_entry_dn, search_entry_dn)

        # Search only the groups for which the object is a member to
        # determine if it is directly or indirectly associated.

        results = []
        for group in memberof:
            try:
                (result, truncated) = self.find_entries(searchfilter, attr_list,
                    group, time_limit=time_limit,size_limit=size_limit,
                    normalize=normalize)
                results.extend(list(result))
            except errors.NotFound:
                pass

        direct = []
        indirect = []
        # If there is an exception here, it is likely due to a failure in
        # referential integrity. All members should have corresponding
        # memberOf entries.
        for m in memberof:
            indirect.append(m.lower())
        for r in results:
            direct.append(r[0])
            try:
                indirect.remove(r[0].lower())
            except ValueError, e:
                logging.info('Failed to remove'
                    ' indirect entry %s from %s' % r[0], entry_dn)
                raise e

        return (direct, indirect)

    def set_entry_active(self, dn, active):
        """Mark entry active/inactive."""
        assert isinstance(active, bool)
        # get the entry in question
        (dn, entry_attrs) = self.get_entry(dn, ['nsaccountlock'])

        # check nsAccountLock attribute
        account_lock_attr = entry_attrs.get('nsaccountlock', ['false'])
        account_lock_attr = account_lock_attr[0].lower()
        if active:
            if account_lock_attr == 'false':
                raise errors.AlreadyActive()
        else:
            if account_lock_attr == 'true':
                raise errors.AlreadyInactive()

        # LDAP expects string instead of Bool but it also requires it to be TRUE or FALSE,
        # not True or False as Python stringification does. Thus, we uppercase it.
        account_lock_attr = str(not active).upper()

        entry_attrs['nsaccountlock'] = account_lock_attr
        self.update_entry(dn, entry_attrs)

    def activate_entry(self, dn):
        """Mark entry active."""
        self.set_entry_active(dn, True)

    def deactivate_entry(self, dn):
        """Mark entry inactive."""
        self.set_entry_active(dn, False)

    def remove_principal_key(self, dn):
        """Remove a kerberos principal key."""

        dn = self.normalize_dn(dn)

        # We need to do this directly using the LDAP library because we
        # don't have read access to krbprincipalkey so we need to delete
        # it in the blind.
        mod = [(_ldap.MOD_REPLACE, 'krbprincipalkey', None),
               (_ldap.MOD_REPLACE, 'krblastpwdchange', None)]

        try:
            self.conn.modify_s(dn, mod)
        except _ldap.LDAPError, e:
            _handle_errors(e, **{})

    # CrudBackend methods

    def _get_normalized_entry_for_crud(self, dn, attrs_list=None):
        (dn, entry_attrs) = self.get_entry(dn, attrs_list)
        entry_attrs['dn'] = dn
        return entry_attrs

    def create(self, **kw):
        """
        Create a new entry and return it as one dict (DN included).

        Extends CrudBackend.create.
        """
        assert 'dn' in kw
        dn = kw['dn']
        del kw['dn']
        self.add_entry(dn, kw)
        return self._get_normalized_entry_for_crud(dn)

    def retrieve(self, primary_key, attributes):
        """
        Get entry by primary_key (DN) as one dict (DN included).

        Extends CrudBackend.retrieve.
        """
        return self._get_normalized_entry_for_crud(primary_key, attributes)

    def update(self, primary_key, **kw):
        """
        Update entry's attributes and return it as one dict (DN included).

        Extends CrudBackend.update.
        """
        self.update_entry(primary_key, kw)
        return self._get_normalized_entry_for_crud(primary_key)

    def delete(self, primary_key):
        """
        Delete entry by primary_key (DN).

        Extends CrudBackend.delete.
        """
        self.delete_entry(primary_key)

    def search(self, **kw):
        """
        Return a list of entries (each entry is one dict, DN included) matching
        the specified criteria.

        Keyword arguments:
        filter -- search filter (default: '')
        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)

        Extends CrudBackend.search.
        """
        # get keyword arguments
        filter = kw.pop('filter', None)
        attrs_list = kw.pop('attrs_list', None)
        base_dn = kw.pop('base_dn', '')
        scope = kw.pop('scope', self.SCOPE_SUBTREE)

        # generate filter
        filter_tmp = self.make_filter(kw)
        if filter:
            filter = self.combine_filters((filter, filter_tmp), self.MATCH_ALL)
        else:
            filter = filter_tmp
        if not filter:
            filter = '(objectClass=*)'

        # find entries and normalize the output for CRUD
        output = []
        (entries, truncated) = self.find_entries(
            filter, attrs_list, base_dn, scope
        )
        for (dn, entry_attrs) in entries:
            entry_attrs['dn'] = [dn]
            output.append(entry_attrs)

        if truncated:
            return (-1, output)
        return (len(output), output)

api.register(ldap2)