source4/scripting/bin/samba_dnsupdate

   1 #!/usr/bin/env python
   2 #
   3 # update our DNS names using TSIG-GSS
   4 #
   5 # Copyright (C) Andrew Tridgell 2010
   6 #
   7 # This program is free software; you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # This program is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19
  20
  21 import os
  22 import fcntl
  23 import sys
  24 import tempfile
  25 import subprocess
  26
  27 # ensure we get messages out immediately, so they get in the samba logs,
  28 # and don't get swallowed by a timeout
  29 os.environ['PYTHONUNBUFFERED'] = '1'
  30
  31 # forcing GMT avoids a problem in some timezones with kerberos. Both MIT
  32 # heimdal can get mutual authentication errors due to the 24 second difference
  33 # between UTC and GMT when using some zone files (eg. the PDT zone from
  34 # the US)
  35 os.environ["TZ"] = "GMT"
  36
  37 # Find right directory when running from source tree
  38 sys.path.insert(0, "bin/python")
  39
  40 import samba
  41 import optparse
  42 from samba import getopt as options
  43 from ldb import SCOPE_BASE
  44 from samba.auth import system_session
  45 from samba.samdb import SamDB
  46 from samba.dcerpc import netlogon, winbind
  47
  48 samba.ensure_external_module("dns", "dnspython")
  49 import dns.resolver
  50 import dns.exception
  51
  52 default_ttl = 900
  53 am_rodc = False
  54 error_count = 0
  55
  56 parser = optparse.OptionParser("samba_dnsupdate")
  57 sambaopts = options.SambaOptions(parser)
  58 parser.add_option_group(sambaopts)
  59 parser.add_option_group(options.VersionOptions(parser))
  60 parser.add_option("--verbose", action="store_true")
  61 parser.add_option("--all-names", action="store_true")
  62 parser.add_option("--all-interfaces", action="store_true")
  63 parser.add_option("--use-file", type="string", help="Use a file, rather than real DNS calls")
  64 parser.add_option("--update-list", type="string", help="Add DNS names from the given file")
  65 parser.add_option("--fail-immediately", action='store_true', help="Exit on first failure")
  66
  67 creds = None
  68 ccachename = None
  69
  70 opts, args = parser.parse_args()
  71
  72 if len(args) != 0:
  73     parser.print_usage()
  74     sys.exit(1)
  75
  76 lp = sambaopts.get_loadparm()
  77
  78 domain = lp.get("realm")
  79 host = lp.get("netbios name")
  80 if opts.all_interfaces:
  81     all_interfaces = True
  82 else:
  83     all_interfaces = False
  84
  85 IPs = samba.interface_ips(lp, all_interfaces)
  86 nsupdate_cmd = lp.get('nsupdate command')
  87
  88 if len(IPs) == 0:
  89     print "No IP interfaces - skipping DNS updates"
  90     sys.exit(0)
  91
  92 IP6s = []
  93 IP4s = []
  94 for i in IPs:
  95     if i.find(':') != -1:
  96         if i.find('%') == -1:
  97             # we don't want link local addresses for DNS updates
  98             IP6s.append(i)
  99     else:
 100         IP4s.append(i)
 101
 102
 103 if opts.verbose:
 104     print "IPs: %s" % IPs
 105
 106 ########################################################
 107 # get credentials if we haven't got them already
 108 def get_credentials(lp):
 109     from samba import credentials
 110     global ccachename, creds
 111     if creds is not None:
 112         return
 113     creds = credentials.Credentials()
 114     creds.guess(lp)
 115     creds.set_machine_account(lp)
 116     creds.set_krb_forwardable(credentials.NO_KRB_FORWARDABLE)
 117     (tmp_fd, ccachename) = tempfile.mkstemp()
 118     creds.get_named_ccache(lp, ccachename)
 119
 120
 121 #############################################
 122 # an object to hold a parsed DNS line
 123 class dnsobj(object):
 124     def __init__(self, string_form):
 125         list = string_form.split()
 126         self.dest = None
 127         self.port = None
 128         self.ip = None
 129         self.existing_port = None
 130         self.existing_weight = None
 131         self.type = list[0]
 132         self.name = list[1].lower()
 133         if self.type == 'SRV':
 134             self.dest = list[2].lower()
 135             self.port = list[3]
 136         elif self.type in ['A', 'AAAA']:
 137             self.ip   = list[2] # usually $IP, which gets replaced
 138         elif self.type == 'CNAME':
 139             self.dest = list[2].lower()
 140         else:
 141             print "Received unexpected DNS reply of type %s" % self.type
 142             raise
 143
 144     def __str__(self):
 145         if d.type == "A":     return "%s %s %s" % (self.type, self.name, self.ip)
 146         if d.type == "AAAA":  return "%s %s %s" % (self.type, self.name, self.ip)
 147         if d.type == "SRV":   return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
 148         if d.type == "CNAME": return "%s %s %s" % (self.type, self.name, self.dest)
 149
 150
 151 ################################################
 152 # parse a DNS line from
 153 def parse_dns_line(line, sub_vars):
 154     subline = samba.substitute_var(line, sub_vars)
 155     d = dnsobj(subline)
 156     return d
 157
 158 ############################################
 159 # see if two hostnames match
 160 def hostname_match(h1, h2):
 161     h1 = str(h1)
 162     h2 = str(h2)
 163     return h1.lower().rstrip('.') == h2.lower().rstrip('.')
 164
 165
 166 ############################################
 167 # check that a DNS entry exists
 168 def check_dns_name(d):
 169     normalised_name = d.name.rstrip('.') + '.'
 170     if opts.verbose:
 171         print "Looking for DNS entry %s as %s" % (d, normalised_name)
 172
 173     if opts.use_file is not None:
 174         try:
 175             dns_file = open(opts.use_file, "r")
 176         except IOError:
 177             return False
 178
 179         for line in dns_file:
 180             line = line.strip()
 181             if line == '' or line[0] == "#":
 182                 continue
 183             if line.lower() == str(d).lower():
 184                 return True
 185         return False
 186
 187     try:
 188         ans = dns.resolver.query(normalised_name, d.type)
 189     except dns.exception.DNSException:
 190         if opts.verbose:
 191             print "Failed to find DNS entry %s" % d
 192         return False
 193     if d.type in ['A', 'AAAA']:
 194         # we need to be sure that our IP is there
 195         for rdata in ans:
 196             if str(rdata) == str(d.ip):
 197                 return True
 198     if d.type == 'CNAME':
 199         for i in range(len(ans)):
 200             if hostname_match(ans[i].target, d.dest):
 201                 return True
 202     if d.type == 'SRV':
 203         for rdata in ans:
 204             if opts.verbose:
 205                 print "Checking %s against %s" % (rdata, d)
 206             if hostname_match(rdata.target, d.dest):
 207                 if str(rdata.port) == str(d.port):
 208                     return True
 209                 else:
 210                     d.existing_port     = str(rdata.port)
 211                     d.existing_weight = str(rdata.weight)
 212
 213     if opts.verbose:
 214         print "Failed to find matching DNS entry %s" % d
 215
 216     return False
 217
 218
 219 ###########################################
 220 # get the list of substitution vars
 221 def get_subst_vars():
 222     global lp, am_rodc
 223     vars = {}
 224
 225     samdb = SamDB(url=lp.samdb_url(), session_info=system_session(),
 226                   lp=lp)
 227
 228     vars['DNSDOMAIN'] = samdb.domain_dns_name()
 229     vars['DNSFOREST'] = samdb.forest_dns_name()
 230     vars['HOSTNAME']  = samdb.host_dns_name()
 231     vars['NTDSGUID']  = samdb.get_ntds_GUID()
 232     vars['SITE']      = samdb.server_site_name()
 233     res = samdb.search(base=samdb.get_default_basedn(), scope=SCOPE_BASE, attrs=["objectGUID"])
 234     guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
 235     vars['DOMAINGUID'] = guid
 236     am_rodc = samdb.am_rodc()
 237
 238     return vars
 239
 240
 241 ############################################
 242 # call nsupdate for an entry
 243 def call_nsupdate(d):
 244     global ccachename, nsupdate_cmd
 245
 246     if opts.verbose:
 247         print "Calling nsupdate for %s" % d
 248
 249     if opts.use_file is not None:
 250         wfile = open(opts.use_file, 'a')
 251         fcntl.lockf(wfile, fcntl.LOCK_EX)
 252         wfile.write(str(d)+"\n")
 253         fcntl.lockf(wfile, fcntl.LOCK_UN)
 254         return
 255
 256     normalised_name = d.name.rstrip('.') + '.'
 257
 258     (tmp_fd, tmpfile) = tempfile.mkstemp()
 259     f = os.fdopen(tmp_fd, 'w')
 260     if d.type == "A":
 261         f.write("update add %s %u A %s\n" % (normalised_name, default_ttl, d.ip))
 262     if d.type == "AAAA":
 263         f.write("update add %s %u AAAA %s\n" % (normalised_name, default_ttl, d.ip))
 264     if d.type == "SRV":
 265         if d.existing_port is not None:
 266             f.write("update delete %s SRV 0 %s %s %s\n" % (normalised_name, d.existing_weight,
 267                                                            d.existing_port, d.dest))
 268         f.write("update add %s %u SRV 0 100 %s %s\n" % (normalised_name, default_ttl, d.port, d.dest))
 269     if d.type == "CNAME":
 270         f.write("update add %s %u CNAME %s\n" % (normalised_name, default_ttl, d.dest))
 271     if opts.verbose:
 272         f.write("show\n")
 273     f.write("send\n")
 274     f.close()
 275
 276     global error_count
 277     os.environ["KRB5CCNAME"] = ccachename
 278     try:
 279         cmd = nsupdate_cmd[:]
 280         cmd.append(tmpfile)
 281         ret = subprocess.call(cmd, shell=False, env={"KRB5CCNAME": ccachename})
 282         if ret != 0:
 283             if opts.fail_immediately:
 284                 sys.exit(1)
 285             error_count = error_count + 1
 286             if opts.verbose:
 287                 print("Failed nsupdate: %d" % ret)
 288     except Exception, estr:
 289         if opts.fail_immediately:
 290             sys.exit(1)
 291         error_count = error_count + 1
 292         if opts.verbose:
 293             print("Failed nsupdate: %s : %s" % (str(d), estr))
 294     os.unlink(tmpfile)
 295
 296
 297
 298 def rodc_dns_update(d, t):
 299     '''a single DNS update via the RODC netlogon call'''
 300     global sub_vars
 301
 302     if opts.verbose:
 303         print "Calling netlogon RODC update for %s" % d
 304
 305     typemap = {
 306         netlogon.NlDnsLdapAtSite       : netlogon.NlDnsInfoTypeNone,
 307         netlogon.NlDnsGcAtSite         : netlogon.NlDnsDomainNameAlias,
 308         netlogon.NlDnsDsaCname         : netlogon.NlDnsDomainNameAlias,
 309         netlogon.NlDnsKdcAtSite        : netlogon.NlDnsInfoTypeNone,
 310         netlogon.NlDnsDcAtSite         : netlogon.NlDnsInfoTypeNone,
 311         netlogon.NlDnsRfc1510KdcAtSite : netlogon.NlDnsInfoTypeNone,
 312         netlogon.NlDnsGenericGcAtSite  : netlogon.NlDnsDomainNameAlias
 313         }
 314
 315     w = winbind.winbind("irpc:winbind_server", lp)
 316     dns_names = netlogon.NL_DNS_NAME_INFO_ARRAY()
 317     dns_names.count = 1
 318     name = netlogon.NL_DNS_NAME_INFO()
 319     name.type = t
 320     name.dns_domain_info_type = typemap[t]
 321     name.priority = 0
 322     name.weight   = 0
 323     if d.port is not None:
 324         name.port = int(d.port)
 325     name.dns_register = True
 326     dns_names.names = [ name ]
 327     site_name = sub_vars['SITE'].decode('utf-8')
 328
 329     global error_count
 330
 331     try:
 332         ret_names = w.DsrUpdateReadOnlyServerDnsRecords(site_name, default_ttl, dns_names)
 333         if ret_names.names[0].status != 0:
 334             print("Failed to set DNS entry: %s (status %u)" % (d, ret_names.names[0].status))
 335             error_count = error_count + 1
 336     except RuntimeError, reason:
 337         print("Error setting DNS entry of type %u: %s: %s" % (t, d, reason))
 338         error_count = error_count + 1
 339
 340     if error_count != 0 and opts.fail_immediately:
 341         sys.exit(1)
 342
 343
 344 def call_rodc_update(d):
 345     '''RODCs need to use the netlogon API for nsupdate'''
 346     global lp, sub_vars
 347
 348     # we expect failure for 3268 if we aren't a GC
 349     if d.port is not None and int(d.port) == 3268:
 350         return
 351
 352     # map the DNS request to a netlogon update type
 353     map = {
 354         netlogon.NlDnsLdapAtSite       : '_ldap._tcp.${SITE}._sites.${DNSDOMAIN}',
 355         netlogon.NlDnsGcAtSite         : '_ldap._tcp.${SITE}._sites.gc._msdcs.${DNSDOMAIN}',
 356         netlogon.NlDnsDsaCname         : '${NTDSGUID}._msdcs.${DNSFOREST}',
 357         netlogon.NlDnsKdcAtSite        : '_kerberos._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 358         netlogon.NlDnsDcAtSite         : '_ldap._tcp.${SITE}._sites.dc._msdcs.${DNSDOMAIN}',
 359         netlogon.NlDnsRfc1510KdcAtSite : '_kerberos._tcp.${SITE}._sites.${DNSDOMAIN}',
 360         netlogon.NlDnsGenericGcAtSite  : '_gc._tcp.${SITE}._sites.${DNSFOREST}'
 361         }
 362
 363     for t in map:
 364         subname = samba.substitute_var(map[t], sub_vars)
 365         if subname.lower() == d.name.lower():
 366             # found a match - do the update
 367             rodc_dns_update(d, t)
 368             return
 369     if opts.verbose:
 370         print("Unable to map to netlogon DNS update: %s" % d)
 371
 372
 373 # get the list of DNS entries we should have
 374 if opts.update_list:
 375     dns_update_list = opts.update_list
 376 else:
 377     dns_update_list = lp.private_path('dns_update_list')
 378
 379 # use our private krb5.conf to avoid problems with the wrong domain
 380 # bind9 nsupdate wants the default domain set
 381 krb5conf = lp.private_path('krb5.conf')
 382 os.environ['KRB5_CONFIG'] = krb5conf
 383
 384 file = open(dns_update_list, "r")
 385
 386 # get the substitution dictionary
 387 sub_vars = get_subst_vars()
 388
 389 # build up a list of update commands to pass to nsupdate
 390 update_list = []
 391 dns_list = []
 392
 393 # read each line, and check that the DNS name exists
 394 for line in file:
 395     line = line.strip()
 396     if line == '' or line[0] == "#":
 397         continue
 398     d = parse_dns_line(line, sub_vars)
 399     if d.type == 'A' and len(IP4s) == 0:
 400         continue
 401     if d.type == 'AAAA' and len(IP6s) == 0:
 402         continue
 403     dns_list.append(d)
 404
 405 # now expand the entries, if any are A record with ip set to $IP
 406 # then replace with multiple entries, one for each interface IP
 407 for d in dns_list:
 408     if d.ip != "$IP":
 409         continue
 410     if d.type == 'A':
 411         d.ip = IP4s[0]
 412         for i in range(len(IP4s)-1):
 413             d2 = dnsobj(str(d))
 414             d2.ip = IP4s[i+1]
 415             dns_list.append(d2)
 416     if d.type == 'AAAA':
 417         d.ip = IP6s[0]
 418         for i in range(len(IP6s)-1):
 419             d2 = dnsobj(str(d))
 420             d2.ip = IP6s[i+1]
 421             dns_list.append(d2)
 422
 423 # now check if the entries already exist on the DNS server
 424 for d in dns_list:
 425     if opts.all_names or not check_dns_name(d):
 426         update_list.append(d)
 427
 428 if len(update_list) == 0:
 429     if opts.verbose:
 430         print "No DNS updates needed"
 431     sys.exit(0)
 432
 433 # get our krb5 creds
 434 get_credentials(lp)
 435
 436 # ask nsupdate to add entries as needed
 437 for d in update_list:
 438     if am_rodc:
 439         if d.name.lower() == domain.lower():
 440             continue
 441         if not d.type in [ 'A', 'AAAA' ]:
 442             call_rodc_update(d)
 443         else:
 444             call_nsupdate(d)
 445     else:
 446         call_nsupdate(d)
 447
 448 # delete the ccache if we created it
 449 if ccachename is not None:
 450     os.unlink(ccachename)
 451
 452 if error_count != 0:
 453     print("Failed update of %u entries" % error_count)
 454 sys.exit(error_count)