summaryrefslogtreecommitdiff
path: root/source4/scripting/bin/samba_dnsupdate
blob: aa307eeed4c8c7b2c7a54641e0d7c78cad6626c9 (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
#!/usr/bin/env python
#
# update our DNS names using TSIG-GSS
#
# Copyright (C) Andrew Tridgell 2010
#
# 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 os
import fcntl
import sys
import tempfile
import subprocess

# ensure we get messages out immediately, so they get in the samba logs,
# and don't get swallowed by a timeout
os.environ['PYTHONUNBUFFERED'] = '1'

# forcing GMT avoids a problem in some timezones with kerberos. Both MIT
# heimdal can get mutual authentication errors due to the 24 second difference
# between UTC and GMT when using some zone files (eg. the PDT zone from
# the US)
os.environ["TZ"] = "GMT"

# Find right directory when running from source tree
sys.path.insert(0, "bin/python")

import samba
import optparse
from samba import getopt as options
from ldb import SCOPE_BASE
from samba.auth import system_session
from samba.samdb import SamDB
from samba.dcerpc import netlogon, winbind

samba.ensure_external_module("dns", "dnspython")
import dns.resolver
import dns.exception

default_ttl = 900
am_rodc = False
error_count = 0

parser = optparse.OptionParser("samba_dnsupdate")
sambaopts = options.SambaOptions(parser)
parser.add_option_group(sambaopts)
parser.add_option_group(options.VersionOptions(parser))
parser.add_option("--verbose", action="store_true")
parser.add_option("--all-names", action="store_true")
parser.add_option("--all-interfaces", action="store_true")
parser.add_option("--use-file", type="string", help="Use a file, rather than real DNS calls")
parser.add_option("--update-list", type="string", help="Add DNS names from the given file")
parser.add_option("--fail-immediately", action='store_true', help="Exit on first failure")
parser.add_option("--no-credentials", dest='nocreds', action='store_true', help="don't try and get credentials")

creds = None
ccachename = None

opts, args = parser.parse_args()

if len(args) != 0:
    parser.print_usage()
    sys.exit(1)

lp = sambaopts.get_loadparm()

domain = lp.get("realm")
host = lp.get("netbios name")
if opts.all_interfaces:
    all_interfaces = True
else:
    all_interfaces = False

IPs = samba.interface_ips(lp, all_interfaces)
nsupdate_cmd = lp.get('nsupdate command')

if len(IPs) == 0:
    print "No IP interfaces - skipping DNS updates"
    sys.exit(0)

IP6s = []
IP4s = []
for i in IPs:
    if i.find(':') != -1:
        if i.find('%') == -1:
            # we don't want link local addresses for DNS updates
            IP6s.append(i)
    else:
        IP4s.append(i)


if opts.verbose:
    print "IPs: %s" % IPs

########################################################
# get credentials if we haven't got them already
def get_credentials(lp):
    from samba import credentials
    global ccachename, creds
    if creds is not None:
        return
    creds = credentials.Credentials()
    creds.guess(lp)
    creds.set_machine_account(lp)
    creds.set_krb_forwardable(credentials.NO_KRB_FORWARDABLE)
    (tmp_fd, ccachename) = tempfile.mkstemp()
    creds.get_named_ccache(lp, ccachename)


#############################################
# an object to hold a parsed DNS line
class dnsobj(object):
    def __init__(self, string_form):
        list = string_form.split()
        self.dest = None
        self.port = None
        self.ip = None
        self.existing_port = None
        self.existing_weight = None
        self.type = list[0]
        self.name = list[1].lower()
        if self.type == 'SRV':
            self.dest = list[2].lower()
            self.port = list[3]
        elif self.type in ['A', 'AAAA']:
            self.ip   = list[2] # usually $IP, which gets replaced
        elif self.type == 'CNAME':
            self.dest = list[2].lower()
        elif self.type == 'NS':
            self.dest = list[2].lower()
        else:
            print "Received unexpected DNS reply of type %s" % self.type
            raise

    def __str__(self):
        if d.type == "A":     return "%s %s %s" % (self.type, self.name, self.ip)
        if d.type == "AAAA":  return "%s %s %s" % (self.type, self.name, self.ip)
        if d.type == "SRV":   return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
        if d.type == "CNAME": return "%s %s %s" % (self.type, self.name, self.dest)
        if d.type == "NS":    return "%s %s %s" % (self.type, self.name, self.dest)


################################################
# parse a DNS line from
def parse_dns_line(line, sub_vars):
    subline = samba.substitute_var(line, sub_vars)
    d = dnsobj(subline)
    return d

############################################
# see if two hostnames match
def hostname_match(h1, h2):
    h1 = str(h1)
    h2 = str(h2)
    return h1.lower().rstrip('.') == h2.lower().rstrip('.')


############################################
# check that a DNS entry exists
def check_dns_name(d):
    normalised_name = d.name.rstrip('.') + '.'
    if opts.verbose:
        print "Looking for DNS entry %s as %s" % (d, normalised_name)
 
    if opts.use_file is not None:
        try:
            dns_file = open(opts.use_file, "r")
        except IOError:
            return False
        
        for line in dns_file:
            line = line.strip()
            if line == '' or line[0] == "#":
                continue
            if line.lower() == str(d).lower():
                return True
        return False

    resolver = dns.resolver.Resolver()
    if d.type == "NS":
        # we need to lookup the nameserver for the parent domain,
        # and use that to check the NS record
        parent_domain = '.'.join(normalised_name.split('.')[1:])
        try:
            ans = resolver.query(parent_domain, 'NS')
        except dns.exception.DNSException:
            if opts.verbose:
                print "Failed to find parent NS for %s" % d
            return False
        nameservers = set()
        for i in range(len(ans)):
            try:
                ns = resolver.query(str(ans[i]), 'A')
            except dns.exception.DNSException:
                continue
            for j in range(len(ns)):
                nameservers.add(str(ns[j]))
        d.nameservers = list(nameservers)

    try:
        if getattr(d, 'nameservers', None):
            resolver.nameservers = list(d.nameservers)
        ans = resolver.query(normalised_name, d.type)
    except dns.exception.DNSException:
        if opts.verbose:
            print "Failed to find DNS entry %s" % d
        return False
    if d.type in ['A', 'AAAA']:
        # we need to be sure that our IP is there
        for rdata in ans:
            if str(rdata) == str(d.ip):
                return True
    if d.type == 'CNAME':
        for i in range(len(ans)):
            if hostname_match(ans[i].target, d.dest):
                return True
    if d.type == 'NS':
        for i in range(len(ans)):
            if hostname_match(ans[i].target, d.dest):
                return True
    if d.type == 'SRV':
        for rdata in ans:
            if opts.verbose:
                print "Checking %s against %s" % (rdata, d)
            if hostname_match(rdata.target, d.dest):
                if str(rdata.port) == str(d.port):
                    return True
                else:
                    d.existing_port     = str(rdata.port)
                    d.existing_weight = str(rdata.weight)

    if opts.verbose:
        print "Failed to find matching DNS entry %s" % d

    return False


###########################################
# get the list of substitution vars
def get_subst_vars():
    global lp, am_rodc
    vars = {}

    samdb = SamDB(url=lp.samdb_url(), session_info=system_session(),
                  lp=lp)

    vars['DNSDOMAIN'] = samdb.domain_dns_name()
    vars['DNSFOREST'] = samdb.forest_dns_name()
    vars['HOSTNAME']  = samdb.host_dns_name()
    vars['NTDSGUID']  = samdb.get_ntds_GUID()
    vars['SITE']      = samdb.server_site_name()
    res = samdb.search(base=samdb.get_default_basedn(), scope=SCOPE_BASE, attrs=["objectGUID"])
    guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
    vars['DOMAINGUID'] = guid
    am_rodc = samdb.am_rodc()

    return vars


############################################
# call nsupdate for an entry
def call_nsupdate(d):
    global ccachename, nsupdate_cmd

    if opts.verbose:
        print "Calling nsupdate for %s" % d

    if opts.use_file is not None:
        wfile = open(opts.use_file, 'a')
        fcntl.lockf(wfile, fcntl.LOCK_EX)
        wfile.write(str(d)+"\n")
        fcntl.lockf(wfile, fcntl.LOCK_UN)
        return

    normalised_name = d.name.rstrip('.') + '.'

    (tmp_fd, tmpfile) = tempfile.mkstemp()
    f = os.fdopen(tmp_fd, 'w')
    if getattr(d, 'nameservers', None):
        f.write('server %s\n' % d.nameservers[0])
    if d.type == "A":
        f.write("update add %s %u A %s\n" % (normalised_name, default_ttl, d.ip))
    if d.type == "AAAA":
        f.write("update add %s %u AAAA %s\n" % (normalised_name, default_ttl, d.ip))
    if d.type == "SRV":
        if d.existing_port is not None:
            f.write("update delete %s SRV 0 %s %s %s\n" % (normalised_name, d.existing_weight,
                                                           d.existing_port, d.dest))
        f.write("update add %s %u SRV 0 100 %s %s\n" % (normalised_name, default_ttl, d.port, d.dest))
    if d.type == "CNAME":
        f.write("update add %s %u CNAME %s\n" % (normalised_name, default_ttl, d.dest))
    if d.type == "NS":
        f.write("update add %s %u NS %s\n" % (normalised_name, default_ttl, d.dest))
    if opts.verbose:
        f.write("show\n")
    f.write("send\n")
    f.close()

    global error_count
    if ccachename:
        os.environ["KRB5CCNAME"] = ccachename
    try:
        cmd = nsupdate_cmd[:]
        cmd.append(tmpfile)
        if ccachename:
            env = {"KRB5CCNAME": ccachename}
        else:
            env = {}
        ret = subprocess.call(cmd, shell=False, env=env)
        if ret != 0:
            if opts.fail_immediately:
                if opts.verbose:
                    print("Failed update with %s" % tmpfile)
                sys.exit(1)
            error_count = error_count + 1
            if opts.verbose:
                print("Failed nsupdate: %d" % ret)
    except Exception, estr:
        if opts.fail_immediately:
            sys.exit(1)
        error_count = error_count + 1
        if opts.verbose:
            print("Failed nsupdate: %s : %s" % (str(d), estr))
    os.unlink(tmpfile)



def rodc_dns_update(d, t):
    '''a single DNS update via the RODC netlogon call'''
    global sub_vars

    if opts.verbose:
        print "Calling netlogon RODC update for %s" % d

    typemap = {
        netlogon.NlDnsLdapAtSite       : netlogon.NlDnsInfoTypeNone,
        netlogon.NlDnsGcAtSite         : netlogon.NlDnsDomainNameAlias,
        netlogon.NlDnsDsaCname         : netlogon.NlDnsDomainNameAlias,
        netlogon.NlDnsKdcAtSite        : netlogon.NlDnsInfoTypeNone,
        netlogon.NlDnsDcAtSite         : netlogon.NlDnsInfoTypeNone,
        netlogon.NlDnsRfc1510KdcAtSite : netlogon.NlDnsInfoTypeNone,
        netlogon.NlDnsGenericGcAtSite  : netlogon.NlDnsDomainNameAlias
        }

    w = winbind.winbind("irpc:winbind_server", lp)
    dns_names = netlogon.NL_DNS_NAME_INFO_ARRAY()
    dns_names.count = 1
    name = netlogon.NL_DNS_NAME_INFO()
    name.type = t
    name.dns_domain_info_type = typemap[t]
    name.priority = 0
    name.weight   = 0
    if d.port is not None:
        name.port = int(d.port)
    name.dns_register = True
    dns_names.names = [ name ]
    site_name = sub_vars['SITE'].decode('utf-8')

    global error_count

    try:
        ret_names = w.DsrUpdateReadOnlyServerDnsRecords(site_name, default_ttl, dns_names)
        if ret_names.names[0].status != 0:
            print("Failed to set DNS entry: %s (status %u)" % (d, ret_names.names[0].status))
            error_count = error_count + 1
    except RuntimeError, reason:
        print("Error setting DNS entry of type %u: %s: %s" % (t, d, reason))
        error_count = error_count + 1

    if error_count != 0 and opts.fail_immediately:
        sys.exit(1)


def call_rodc_update(d):
    '''RODCs need to use the netlogon API for nsupdate'''
    global lp, sub_vars

    # we expect failure for 3268 if we aren't a GC
    if d.port is not None and int(d.port) == 3268:
        return

    # map the DNS request to a netlogon update type
    map = {
        netlogon.NlDnsLdapAtSite       : '_ldap._tcp.${SITE}._sites.${DNSDOMAIN}',
        netlogon.NlDnsGcAtSite         : '_ldap._tcp.${SITE}._sites.gc._msdcs.${DNSDOMAIN}',
        netlogon.NlDnsDsaCname         : '${NTDSGUID}._msdcs.${DNSFOREST}',
        netlogon.NlDnsKdcAtSite        : '_kerberos._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
        netlogon.NlDnsDcAtSite         : '_ldap._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
        netlogon.NlDnsRfc1510KdcAtSite : '_kerberos._tcp.${SITE}._sites.${DNSDOMAIN}',
        netlogon.NlDnsGenericGcAtSite  : '_gc._tcp.${SITE}._sites.${DNSFOREST}'
        }

    for t in map:
        subname = samba.substitute_var(map[t], sub_vars)
        if subname.lower() == d.name.lower():
            # found a match - do the update
            rodc_dns_update(d, t)
            return
    if opts.verbose:
        print("Unable to map to netlogon DNS update: %s" % d)


# get the list of DNS entries we should have
if opts.update_list:
    dns_update_list = opts.update_list
else:
    dns_update_list = lp.private_path('dns_update_list')

# use our private krb5.conf to avoid problems with the wrong domain
# bind9 nsupdate wants the default domain set
krb5conf = lp.private_path('krb5.conf')
os.environ['KRB5_CONFIG'] = krb5conf

file = open(dns_update_list, "r")

# get the substitution dictionary
sub_vars = get_subst_vars()

# build up a list of update commands to pass to nsupdate
update_list = []
dns_list = []

dup_set = set()

# read each line, and check that the DNS name exists
for line in file:
    line = line.strip()
    if line == '' or line[0] == "#":
        continue
    d = parse_dns_line(line, sub_vars)
    if d.type == 'A' and len(IP4s) == 0:
        continue
    if d.type == 'AAAA' and len(IP6s) == 0:
        continue
    if str(d) not in dup_set:
        dns_list.append(d)
        dup_set.add(str(d))

# now expand the entries, if any are A record with ip set to $IP
# then replace with multiple entries, one for each interface IP
for d in dns_list:
    if d.ip != "$IP":
        continue
    if d.type == 'A':
        d.ip = IP4s[0]
        for i in range(len(IP4s)-1):
            d2 = dnsobj(str(d))
            d2.ip = IP4s[i+1]
            dns_list.append(d2)
    if d.type == 'AAAA':
        d.ip = IP6s[0]
        for i in range(len(IP6s)-1):
            d2 = dnsobj(str(d))
            d2.ip = IP6s[i+1]
            dns_list.append(d2)

# now check if the entries already exist on the DNS server
for d in dns_list:
    if opts.all_names or not check_dns_name(d):
        update_list.append(d)

if len(update_list) == 0:
    if opts.verbose:
        print "No DNS updates needed"
    sys.exit(0)

# get our krb5 creds
if not opts.nocreds:
    get_credentials(lp)

# ask nsupdate to add entries as needed
for d in update_list:
    if am_rodc:
        if d.name.lower() == domain.lower():
            continue
        if not d.type in [ 'A', 'AAAA' ]:
            call_rodc_update(d)
        else:
            call_nsupdate(d)
    else:
        call_nsupdate(d)

# delete the ccache if we created it
if ccachename is not None:
    os.unlink(ccachename)

if error_count != 0:
    print("Failed update of %u entries" % error_count)
sys.exit(error_count)