summaryrefslogtreecommitdiffstats
path: root/ipalib/util.py
blob: 67865eb04e85ffaf34475f0324cc9cc0703cf45b (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
# Authors:
#   Jason Gerard DeRose <jderose@redhat.com>
#
# Copyright (C) 2008  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/>.

"""
Various utility functions.
"""

from __future__ import absolute_import

import os
import socket
import re
import decimal
import dns
import encodings
from weakref import WeakKeyDictionary

import netaddr
from dns import resolver, rdatatype
from dns.exception import DNSException
from dns.resolver import NXDOMAIN
from netaddr.core import AddrFormatError
import six

from ipalib import errors, messages
from ipalib.constants import DOMAIN_LEVEL_0
from ipalib.text import _
from ipapython.ssh import SSHPublicKey
from ipapython.dn import DN, RDN
from ipapython.dnsutil import DNSName
from ipapython.dnsutil import resolve_ip_addresses

if six.PY3:
    unicode = str


def json_serialize(obj):
    if isinstance(obj, (list, tuple)):
        return [json_serialize(o) for o in obj]
    if isinstance(obj, dict):
        return {k: json_serialize(v) for (k, v) in obj.items()}
    if isinstance(obj, (bool, float, unicode, type(None), six.integer_types)):
        return obj
    if isinstance(obj, str):
        return obj.decode('utf-8')
    if isinstance(obj, (decimal.Decimal, DN)):
        return str(obj)
    if not callable(getattr(obj, '__json__', None)):
        # raise TypeError('%r is not JSON serializable')
        return ''
    return json_serialize(obj.__json__())


def verify_host_resolvable(fqdn):
    try:
        if not resolve_ip_addresses(fqdn):
            raise errors.DNSNotARecordError(hostname=fqdn)
    except dns.exception.DNSException as ex:
        # wrap DNSException in a PublicError
        raise errors.DNSResolverError(exception=ex)


def has_soa_or_ns_record(domain):
    """
    Checks to see if given domain has SOA or NS record.
    Returns True or False.
    """
    try:
        resolver.query(domain, rdatatype.SOA)
        soa_record_found = True
    except DNSException:
        soa_record_found = False

    try:
        resolver.query(domain, rdatatype.NS)
        ns_record_found = True
    except DNSException:
        ns_record_found = False

    return soa_record_found or ns_record_found


def normalize_name(name):
    result = dict()
    components = name.split('@')
    if len(components) == 2:
        result['domain'] = unicode(components[1]).lower()
        result['name'] = unicode(components[0]).lower()
    else:
        components = name.split('\\')
        if len(components) == 2:
            result['flatname'] = unicode(components[0]).lower()
            result['name'] = unicode(components[1]).lower()
        else:
            result['name'] = unicode(name).lower()
    return result

def isvalid_base64(data):
    """
    Validate the incoming data as valid base64 data or not.

    The character set must only include of a-z, A-Z, 0-9, + or / and
    be padded with = to be a length divisible by 4 (so only 0-2 =s are
    allowed). Its length must be divisible by 4. White space is
    not significant so it is removed.

    This doesn't guarantee we have a base64-encoded value, just that it
    fits the base64 requirements.
    """

    data = ''.join(data.split())

    if len(data) % 4 > 0 or \
        re.match('^[a-zA-Z0-9\+\/]+\={0,2}$', data) is None:
        return False
    else:
        return True

def validate_ipaddr(ipaddr):
    """
    Check to see if the given IP address is a valid IPv4 or IPv6 address.

    Returns True or False
    """
    try:
        socket.inet_pton(socket.AF_INET, ipaddr)
    except socket.error:
        try:
            socket.inet_pton(socket.AF_INET6, ipaddr)
        except socket.error:
            return False
    return True

def check_writable_file(filename):
    """
    Determine if the file is writable. If the file doesn't exist then
    open the file to test writability.
    """
    if filename is None:
        raise errors.FileError(reason=_('Filename is empty'))
    try:
        if os.path.exists(filename):
            if not os.access(filename, os.W_OK):
                raise errors.FileError(reason=_('Permission denied: %(file)s') % dict(file=filename))
        else:
            fp = open(filename, 'w')
            fp.close()
    except (IOError, OSError) as e:
        raise errors.FileError(reason=str(e))

def normalize_zonemgr(zonemgr):
    if not zonemgr or not isinstance(zonemgr, six.string_types):
        return zonemgr
    if '@' in zonemgr:
        # local-part needs to be normalized
        name, at, domain = zonemgr.partition('@')
        name = name.replace('.', '\\.')
        zonemgr = u''.join((name, u'.', domain))

    return zonemgr

def normalize_zone(zone):
    if zone[-1] != '.':
        return zone + '.'
    else:
        return zone


def validate_dns_label(dns_label, allow_underscore=False, allow_slash=False):
    base_chars = 'a-z0-9'
    extra_chars = ''
    middle_chars = ''

    if allow_underscore:
        extra_chars += '_'
    if allow_slash:
        middle_chars += '/'

    middle_chars = middle_chars + '-' #has to be always the last in the regex [....-]

    label_regex = r'^[%(base)s%(extra)s]([%(base)s%(extra)s%(middle)s]?[%(base)s%(extra)s])*$' \
        % dict(base=base_chars, extra=extra_chars, middle=middle_chars)
    regex = re.compile(label_regex, re.IGNORECASE)

    if not dns_label:
        raise ValueError(_('empty DNS label'))

    if len(dns_label) > 63:
        raise ValueError(_('DNS label cannot be longer that 63 characters'))

    if not regex.match(dns_label):
        chars = ', '.join("'%s'" % c for c in extra_chars + middle_chars)
        chars2 = ', '.join("'%s'" % c for c in middle_chars)
        raise ValueError(_("only letters, numbers, %(chars)s are allowed. " \
                           "DNS label may not start or end with %(chars2)s") \
                           % dict(chars=chars, chars2=chars2))


def validate_domain_name(domain_name, allow_underscore=False, allow_slash=False):
    if domain_name.endswith('.'):
        domain_name = domain_name[:-1]

    domain_name = domain_name.split(".")

    # apply DNS name validator to every name part
    for label in domain_name:
        validate_dns_label(label, allow_underscore, allow_slash)


def validate_zonemgr(zonemgr):
    assert isinstance(zonemgr, DNSName)
    if any('@' in label for label in zonemgr.labels):
        raise ValueError(_('too many \'@\' characters'))


def validate_zonemgr_str(zonemgr):
    zonemgr = normalize_zonemgr(zonemgr)
    validate_idna_domain(zonemgr)
    zonemgr = DNSName(zonemgr)
    return validate_zonemgr(zonemgr)

def validate_hostname(hostname, check_fqdn=True, allow_underscore=False, allow_slash=False):
    """ See RFC 952, 1123

    :param hostname Checked value
    :param check_fqdn Check if hostname is fully qualified
    """
    if len(hostname) > 255:
        raise ValueError(_('cannot be longer that 255 characters'))

    if hostname.endswith('.'):
        hostname = hostname[:-1]

    if '..' in hostname:
        raise ValueError(_('hostname contains empty label (consecutive dots)'))

    if '.' not in hostname:
        if check_fqdn:
            raise ValueError(_('not fully qualified'))
        validate_dns_label(hostname, allow_underscore, allow_slash)
    else:
        validate_domain_name(hostname, allow_underscore, allow_slash)

def normalize_sshpubkey(value):
    return SSHPublicKey(value).openssh()

def validate_sshpubkey(ugettext, value):
    try:
        SSHPublicKey(value)
    except (ValueError, UnicodeDecodeError):
        return _('invalid SSH public key')

def validate_sshpubkey_no_options(ugettext, value):
    try:
        pubkey = SSHPublicKey(value)
    except (ValueError, UnicodeDecodeError):
        return _('invalid SSH public key')

    if pubkey.has_options():
        return _('options are not allowed')


def convert_sshpubkey_post(entry_attrs):
    pubkeys = entry_attrs.get('ipasshpubkey')
    if not pubkeys:
        return

    newpubkeys = []
    fingerprints = []
    for pubkey in pubkeys:
        try:
            pubkey = SSHPublicKey(pubkey)
        except (ValueError, UnicodeDecodeError):
            continue

        fp = pubkey.fingerprint_hex_md5()
        comment = pubkey.comment()
        if comment:
            fp = u'%s %s' % (fp, comment)
        fp = u'%s (%s)' % (fp, pubkey.keytype())

        newpubkeys.append(pubkey.openssh())
        fingerprints.append(fp)

    if 'ipasshpubkey' in entry_attrs:
        entry_attrs['ipasshpubkey'] = newpubkeys or None
    if fingerprints:
        entry_attrs['sshpubkeyfp'] = fingerprints


def add_sshpubkey_to_attrs_pre(context, attrs_list):
    """
    Attribute ipasshpubkey should be added to attrs_list to be able compute
    ssh fingerprint. This attribute must be removed later if was added here
    (see remove_sshpubkey_from_output_post).
    """
    if not ('ipasshpubkey' in attrs_list or '*' in attrs_list):
        setattr(context, 'ipasshpubkey_added', True)
        attrs_list.append('ipasshpubkey')


def remove_sshpubkey_from_output_post(context, entry_attrs):
    """
    Remove ipasshpubkey from output if it was added in pre_callbacks
    """
    if getattr(context, 'ipasshpubkey_added', False):
        entry_attrs.pop('ipasshpubkey', None)
        delattr(context, 'ipasshpubkey_added')


def remove_sshpubkey_from_output_list_post(context, entries):
    """
    Remove ipasshpubkey from output if it was added in pre_callbacks
    """
    if getattr(context, 'ipasshpubkey_added', False):
        for entry_attrs in entries:
            entry_attrs.pop('ipasshpubkey', None)
        delattr(context, 'ipasshpubkey_added')


class cachedproperty(object):
    """
    A property-like attribute that caches the return value of a method call.

    When the attribute is first read, the method is called and its return
    value is saved and returned. On subsequent reads, the saved value is
    returned.

    Typical usage:
    class C(object):
        @cachedproperty
        def attr(self):
            return 'value'
    """
    __slots__ = ('getter', 'store')

    def __init__(self, getter):
        self.getter = getter
        self.store = WeakKeyDictionary()

    def __get__(self, obj, cls):
        if obj is None:
            return None
        if obj not in self.store:
            self.store[obj] = self.getter(obj)
        return self.store[obj]

    def __set__(self, obj, value):
        raise AttributeError("can't set attribute")

    def __delete__(self, obj):
        raise AttributeError("can't delete attribute")

# regexp matching signed floating point number (group 1) followed by
# optional whitespace followed by time unit, e.g. day, hour (group 7)
time_duration_re = re.compile(r'([-+]?((\d+)|(\d+\.\d+)|(\.\d+)|(\d+\.)))\s*([a-z]+)', re.IGNORECASE)

# number of seconds in a time unit
time_duration_units = {
    'year'    : 365*24*60*60,
    'years'   : 365*24*60*60,
    'y'       : 365*24*60*60,
    'month'   : 30*24*60*60,
    'months'  : 30*24*60*60,
    'week'    : 7*24*60*60,
    'weeks'   : 7*24*60*60,
    'w'       : 7*24*60*60,
    'day'     : 24*60*60,
    'days'    : 24*60*60,
    'd'       : 24*60*60,
    'hour'    : 60*60,
    'hours'   : 60*60,
    'h'       : 60*60,
    'minute'  : 60,
    'minutes' : 60,
    'min'     : 60,
    'second'  : 1,
    'seconds' : 1,
    'sec'     : 1,
    's'       : 1,
}

def parse_time_duration(value):
    '''

    Given a time duration string, parse it and return the total number
    of seconds represented as a floating point value. Negative values
    are permitted.

    The string should be composed of one or more numbers followed by a
    time unit. Whitespace and punctuation is optional. The numbers may
    be optionally signed.  The time units are case insenstive except
    for the single character 'M' or 'm' which means month and minute
    respectively.

    Recognized time units are:

        * year, years, y
        * month, months, M
        * week, weeks, w
        * day, days, d
        * hour, hours, h
        * minute, minutes, min, m
        * second, seconds, sec, s

    Examples:
        "1h"                    # 1 hour
        "2 HOURS, 30 Minutes"   # 2.5 hours
        "1week -1 day"          # 6 days
        ".5day"                 # 12 hours
        "2M"                    # 2 months
        "1h:15m"                # 1.25 hours
        "1h, -15min"            # 45 minutes
        "30 seconds"            # .5 minute

    Note: Despite the appearance you can perform arithmetic the
    parsing is much simpler, the parser searches for signed values and
    adds the signed value to a running total. Only + and - are permitted
    and must appear prior to a digit.

    :parameters:
        value : string
            A time duration string in the specified format
    :returns:
        total number of seconds as float (may be negative)
    '''

    matches = 0
    duration = 0.0
    for match in time_duration_re.finditer(value):
        matches += 1
        magnitude = match.group(1)
        unit = match.group(7)

        # Get the unit, only M and m are case sensitive
        if unit == 'M':         # month
            seconds_per_unit = 30*24*60*60
        elif unit == 'm':       # minute
            seconds_per_unit = 60
        else:
            unit = unit.lower()
            seconds_per_unit = time_duration_units.get(unit)
            if seconds_per_unit is None:
                raise ValueError('unknown time duration unit "%s"' % unit)
        magnitude = float(magnitude)
        seconds = magnitude * seconds_per_unit
        duration += seconds

    if matches == 0:
        raise ValueError('no time duration found in "%s"' % value)

    return duration

def get_dns_forward_zone_update_policy(realm, rrtypes=('A', 'AAAA', 'SSHFP')):
    """
    Generate update policy for a forward DNS zone (idnsUpdatePolicy
    attribute). Bind uses this policy to grant/reject access for client
    machines trying to dynamically update their records.

    :param realm: A realm of the of the client
    :param rrtypes: A list of resource records types that client shall be
                    allowed to update
    """
    policy_element = "grant %(realm)s krb5-self * %(rrtype)s"
    policies = [ policy_element % dict(realm=realm, rrtype=rrtype) \
               for rrtype in rrtypes ]
    policy = "; ".join(policies)
    policy += ";"

    return policy

def get_dns_reverse_zone_update_policy(realm, reverse_zone, rrtypes=('PTR',)):
    """
    Generate update policy for a reverse DNS zone (idnsUpdatePolicy
    attribute). Bind uses this policy to grant/reject access for client
    machines trying to dynamically update their records.

    :param realm: A realm of the of the client
    :param reverse_zone: Name of the actual zone. All clients with IPs in this
                         sub-domain will be allowed to perform changes
    :param rrtypes: A list of resource records types that client shall be
                    allowed to update
    """
    policy_element = "grant %(realm)s krb5-subdomain %(zone)s %(rrtype)s"
    policies = [ policy_element \
                    % dict(realm=realm, zone=reverse_zone, rrtype=rrtype) \
                 for rrtype in rrtypes ]
    policy = "; ".join(policies)
    policy += ";"

    return policy

# dictionary of valid reverse zone -> number of address components
REVERSE_DNS_ZONES = {
    DNSName.ip4_rev_zone : 4,
    DNSName.ip6_rev_zone : 32,
}

def zone_is_reverse(zone_name):
    return DNSName(zone_name).is_reverse()

def get_reverse_zone_default(ip_address):
    ip = netaddr.IPAddress(str(ip_address))
    items = ip.reverse_dns.split('.')

    if ip.version == 4:
        items = items[1:]   # /24 for IPv4
    elif ip.version == 6:
        items = items[16:]  # /64 for IPv6

    return normalize_zone('.'.join(items))

def validate_rdn_param(ugettext, value):
    try:
        rdn = RDN(value)
    except Exception as e:
        return str(e)
    return None

def validate_hostmask(ugettext, hostmask):
    try:
        netaddr.IPNetwork(hostmask)
    except (ValueError, AddrFormatError):
        return _('invalid hostmask')


class ForwarderValidationError(Exception):
    format = None

    def __init__(self, format=None, message=None, **kw):
        messages.process_message_arguments(self, format, message, **kw)
        super(ForwarderValidationError, self).__init__(self.msg)


class UnresolvableRecordError(ForwarderValidationError):
    format = _("query '%(owner)s %(rtype)s': %(error)s")


class EDNS0UnsupportedError(ForwarderValidationError):
    format = _("query '%(owner)s %(rtype)s' with EDNS0: %(error)s")


class DNSSECSignatureMissingError(ForwarderValidationError):
    format = _("answer to query '%(owner)s %(rtype)s' is missing DNSSEC "
               "signatures (no RRSIG data)")


class DNSSECValidationError(ForwarderValidationError):
    format = _("record '%(owner)s %(rtype)s' "
               "failed DNSSEC validation on server %(ip)s")


def _log_response(log, e):
    """
    If exception contains response from server, log this response to debug log
    :param log: if log is None, do not log
    :param e: DNSException
    """
    assert isinstance(e, DNSException)
    if log is not None:
        response = getattr(e, 'kwargs', {}).get('response')
        if response:
            log.debug("DNSException: %s; server response: %s", e, response)


def _resolve_record(owner, rtype, nameserver_ip=None, edns0=False,
                    dnssec=False, flag_cd=False, timeout=10):
    """
    :param nameserver_ip: if None, default resolvers will be used
    :param edns0: enables EDNS0
    :param dnssec: enabled EDNS0, flags: DO
    :param flag_cd: requires dnssec=True, adds flag CD
    :raise DNSException: if error occurs
    """
    assert isinstance(nameserver_ip, six.string_types)
    assert isinstance(rtype, six.string_types)

    res = dns.resolver.Resolver()
    if nameserver_ip:
        res.nameservers = [nameserver_ip]
    res.lifetime = timeout

    # Recursion Desired,
    # this option prevents to get answers in authority section instead of answer
    res.set_flags(dns.flags.RD)

    if dnssec:
        res.use_edns(0, dns.flags.DO, 4096)
        flags = dns.flags.RD
        if flag_cd:
            flags = flags | dns.flags.CD
        res.set_flags(flags)
    elif edns0:
        res.use_edns(0, 0, 4096)

    return res.query(owner, rtype)


def _validate_edns0_forwarder(owner, rtype, ip_addr, log=None, timeout=10):
    """
    Validate if forwarder supports EDNS0

    :raise UnresolvableRecordError: record cannot be resolved
    :raise EDNS0UnsupportedError: EDNS0 is not supported by forwarder
    """

    try:
        _resolve_record(owner, rtype, nameserver_ip=ip_addr, timeout=timeout)
    except DNSException as e:
        _log_response(log, e)
        raise UnresolvableRecordError(owner=owner, rtype=rtype, ip=ip_addr,
                                      error=e)

    try:
        _resolve_record(owner, rtype, nameserver_ip=ip_addr, edns0=True,
                        timeout=timeout)
    except DNSException as e:
        _log_response(log, e)
        raise EDNS0UnsupportedError(owner=owner, rtype=rtype, ip=ip_addr,
                                    error=e)


def validate_dnssec_global_forwarder(ip_addr, log=None, timeout=10):
    """Test DNS forwarder properties. against root zone.

    Global forwarders should be able return signed root zone

    :raise UnresolvableRecordError: record cannot be resolved
    :raise EDNS0UnsupportedError: EDNS0 is not supported by forwarder
    :raise DNSSECSignatureMissingError: did not receive RRSIG for root zone
    """

    ip_addr = str(ip_addr)
    owner = "."
    rtype = "SOA"

    _validate_edns0_forwarder(owner, rtype, ip_addr, log=log, timeout=timeout)

    # DNS root has to be signed
    try:
        ans = _resolve_record(owner, rtype, nameserver_ip=ip_addr, dnssec=True,
                              timeout=timeout)
    except DNSException as e:
        _log_response(log, e)
        raise UnresolvableRecordError(owner=owner, rtype=rtype, ip=ip_addr,
                                      error=e)

    try:
        ans.response.find_rrset(
            ans.response.answer, dns.name.root, dns.rdataclass.IN,
            dns.rdatatype.RRSIG, dns.rdatatype.SOA
        )
    except KeyError:
        raise DNSSECSignatureMissingError(owner=owner, rtype=rtype, ip=ip_addr)


def validate_dnssec_zone_forwarder_step1(ip_addr, fwzone, log=None, timeout=10):
    """
    Only forwarders in forward zones can be validated in this way
    :raise UnresolvableRecordError: record cannot be resolved
    :raise EDNS0UnsupportedError: ENDS0 is not supported by forwarder
    """
    _validate_edns0_forwarder(fwzone, "SOA", ip_addr, log=log, timeout=timeout)


def validate_dnssec_zone_forwarder_step2(ipa_ip_addr, fwzone, log=None,
                                         timeout=10):
    """
    This step must be executed after forwarders are added into LDAP, and only
    when we are sure the forwarders work.
    Query will be send to IPA DNS server, to verify if reply passed,
    or DNSSEC validation failed.
    Only forwarders in forward zones can be validated in this way
    :raise UnresolvableRecordError: record cannot be resolved
    :raise DNSSECValidationError: response from forwarder is not DNSSEC valid
    """
    rtype = "SOA"
    try:
        ans_cd = _resolve_record(fwzone, rtype, nameserver_ip=ipa_ip_addr,
                                 edns0=True, dnssec=True, flag_cd=True,
                                 timeout=timeout)
    except NXDOMAIN as e:
        # sometimes CD flag is ignored and NXDomain is returned
        _log_response(log, e)
        raise DNSSECValidationError(owner=fwzone, rtype=rtype, ip=ipa_ip_addr)
    except DNSException as e:
        _log_response(log, e)
        raise UnresolvableRecordError(owner=fwzone, rtype=rtype,
                                      ip=ipa_ip_addr, error=e)

    try:
        ans_do = _resolve_record(fwzone, rtype, nameserver_ip=ipa_ip_addr,
                                 edns0=True, dnssec=True, timeout=timeout)
    except DNSException as e:
        _log_response(log, e)
        raise DNSSECValidationError(owner=fwzone, rtype=rtype, ip=ipa_ip_addr)
    else:
        if (ans_do.canonical_name == ans_cd.canonical_name
            and ans_do.rrset == ans_cd.rrset):
            return
        # records received with and without CD flag are not equivalent:
        # this might be caused by an DNSSEC validation failure in cases where
        # existing zone id being 'shadowed' by another zone on forwarder
        raise DNSSECValidationError(owner=fwzone, rtype=rtype, ip=ipa_ip_addr)


def validate_idna_domain(value):
    """
    Validate if value is valid IDNA domain.

    If domain is not valid, raises ValueError
    :param value:
    :return:
    """
    error = None

    try:
        DNSName(value)
    except dns.name.BadEscape:
        error = _('invalid escape code in domain name')
    except dns.name.EmptyLabel:
        error = _('empty DNS label')
    except dns.name.NameTooLong:
        error = _('domain name cannot be longer than 255 characters')
    except dns.name.LabelTooLong:
        error = _('DNS label cannot be longer than 63 characters')
    except dns.exception.SyntaxError:
        error = _('invalid domain name')
    else:
        #compare if IDN normalized and original domain match
        #there is N:1 mapping between unicode and IDNA names
        #user should use normalized names to avoid mistakes
        labels = re.split(u'[.\uff0e\u3002\uff61]', value, flags=re.UNICODE)
        try:
            for label in labels:
                label.encode("ascii")
        except UnicodeError:
            # IDNA
            is_nonnorm = any(encodings.idna.nameprep(x) != x for x in labels)
            if is_nonnorm:
                error = _("domain name '%(domain)s' should be normalized to"
                          ": %(normalized)s") % {
                          'domain': value,
                          'normalized': '.'.join([encodings.idna.nameprep(x)
                                                  for x in labels])}

    if error:
        raise ValueError(error)


def detect_dns_zone_realm_type(api, domain):
    """
    Detects the type of the realm that the given DNS zone belongs to.
    Note: This method is heuristic. Possible values:
      - 'current': For IPA domains belonging in the current realm.
      - 'foreign': For domains belonging in a foreing kerberos realm.
      - 'unknown': For domains whose allegiance could not be detected.
    """

    # First, try to detect _kerberos TXT record in the domain
    # This would indicate that the domain belongs to IPA realm

    kerberos_prefix = DNSName('_kerberos')
    domain_suffix = DNSName(domain)
    kerberos_record_name = kerberos_prefix + domain_suffix

    response = None

    try:
        result = resolver.query(kerberos_record_name, rdatatype.TXT)
        answer = result.response.answer

        # IPA domain will have only one _kerberos TXT record
        if (len(answer) == 1 and
            len(answer[0]) == 1 and
            answer[0].rdtype == rdatatype.TXT):

            record = answer[0][0]

            # If the record contains our current realm, it is 'ipa-current'
            if record.to_text() == '"{0}"'.format(api.env.realm):
                return 'current'
            else:
                return 'foreign'

    except DNSException as e:
        pass

    # Try to detect AD specific record in the zone.
    # This would indicate that the domain belongs to foreign (AD) realm

    gc_prefix = DNSName('_ldap._tcp.gc._msdcs')
    ad_specific_record_name = gc_prefix + domain_suffix

    try:
        # The presence of this record is enough, return foreign in such case
        result = resolver.query(ad_specific_record_name, rdatatype.SRV)
        return 'foreign'

    except DNSException as e:
        pass

    # If we could not detect type with certainity, return unknown
    return 'unknown'

def has_managed_topology(api):
    domainlevel = api.Command['domainlevel_get']().get('result', DOMAIN_LEVEL_0)
    return domainlevel > DOMAIN_LEVEL_0


class classproperty(object):
    __slots__ = ('__doc__', 'fget')

    def __init__(self, fget=None, doc=None):
        if doc is None and fget is not None:
            doc = fget.__doc__

        self.fget = fget
        self.__doc__ = doc

    def __get__(self, obj, obj_type):
        if self.fget is not None:
            return self.fget.__get__(obj, obj_type)()
        raise AttributeError("unreadable attribute")

    def __set__(self, obj, value):
        raise AttributeError("can't set attribute")

    def __delete__(self, obj):
        raise AttributeError("can't delete attribute")

    def getter(self, fget):
        self.fget = fget
        return self


def normalize_hostname(hostname):
    """Use common fqdn form without the trailing dot"""
    if hostname.endswith(u'.'):
        hostname = hostname[:-1]
    hostname = hostname.lower()
    return hostname


def hostname_validator(ugettext, value):
    try:
        validate_hostname(value)
    except ValueError as e:
        return _('invalid domain-name: %s') % unicode(e)

    return None


def ipaddr_validator(ugettext, ipaddr, ip_version=None):
    try:
        ip = netaddr.IPAddress(str(ipaddr), flags=netaddr.INET_PTON)

        if ip_version is not None:
            if ip.version != ip_version:
                return _(
                    'invalid IP address version (is %(value)d, must be '
                    '%(required_value)d)!') % dict(
                    value=ip.version,
                    required_value=ip_version
                )
    except (netaddr.AddrFormatError, ValueError):
        return _('invalid IP address format')
    return None


def validate_bind_forwarder(ugettext, forwarder):
    ip_address, sep, port = forwarder.partition(u' port ')

    ip_address_validation = ipaddr_validator(ugettext, ip_address)

    if ip_address_validation is not None:
        return ip_address_validation

    if sep:
        try:
            port = int(port)
            if port < 0 or port > 65535:
                raise ValueError()
        except ValueError:
            return _('%(port)s is not a valid port' % dict(port=port))

    return None


def set_krbcanonicalname(entry_attrs):
    objectclasses = set(i.lower() for i in entry_attrs['objectclass'])

    if 'krbprincipalaux' not in objectclasses:
        return

    if ('krbprincipalname' in entry_attrs
            and 'krbcanonicalname' not in entry_attrs):
        entry_attrs['krbcanonicalname'] = entry_attrs['krbprincipalname']