3 # update our DNS names using TSIG-GSS
5 # Copyright (C) Andrew Tridgell 2010
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.
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.
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/>.
26 # ensure we get messages out immediately, so they get in the samba logs,
27 # and don't get swallowed by a timeout
28 os.putenv('PYTHONUNBUFFERED', '1')
30 # Find right directory when running from source tree
31 sys.path.insert(0, "bin/python")
35 from samba import getopt as options
36 from ldb import SCOPE_BASE
37 from samba.auth import system_session
38 from samba.samdb import SamDB
40 samba.ensure_external_module("dns", "dnspython")
41 import dns.resolver as resolver
45 parser = optparse.OptionParser("samba_dnsupdate")
46 sambaopts = options.SambaOptions(parser)
47 parser.add_option_group(sambaopts)
48 parser.add_option_group(options.VersionOptions(parser))
49 parser.add_option("--verbose", action="store_true")
50 parser.add_option("--all-interfaces", action="store_true")
51 parser.add_option("--use-file", type="string", help="Use a file, rather than real DNS calls")
56 opts, args = parser.parse_args()
62 lp = sambaopts.get_loadparm()
64 domain = lp.get("realm")
65 host = lp.get("netbios name")
66 if opts.all_interfaces:
69 all_interfaces = False
71 IPs = samba.interface_ips(lp, all_interfaces)
72 nsupdate_cmd = lp.get('nsupdate command')
75 print "No IP interfaces - skipping DNS updates"
80 ########################################################
81 # get credentials if we haven't got them already
82 def get_credentials(lp):
83 from samba import credentials
84 global ccachename, creds
87 creds = credentials.Credentials()
89 creds.set_machine_account(lp)
90 creds.set_krb_forwardable(credentials.NO_KRB_FORWARDABLE)
91 (tmp_fd, ccachename) = tempfile.mkstemp()
92 creds.get_named_ccache(lp, ccachename)
95 #############################################
96 # an object to hold a parsed DNS line
98 def __init__(self, string_form):
99 list = string_form.split()
103 self.existing_port = None
104 self.existing_weight = None
107 if self.type == 'SRV':
110 elif self.type == 'A':
111 self.ip = list[2] # usually $IP, which gets replaced
112 elif self.type == 'CNAME':
115 print "Received unexpected DNS reply of type %s" % self.type
119 if d.type == "A": return "%s %s %s" % (self.type, self.name, self.ip)
120 if d.type == "SRV": return "%s %s %s %s" % (self.type, self.name, self.dest, self.port)
121 if d.type == "CNAME": return "%s %s %s" % (self.type, self.name, self.dest)
124 ################################################
125 # parse a DNS line from
126 def parse_dns_line(line, sub_vars):
127 subline = samba.substitute_var(line, sub_vars)
131 ############################################
132 # see if two hostnames match
133 def hostname_match(h1, h2):
136 return h1.lower().rstrip('.') == h2.lower().rstrip('.')
139 ############################################
140 # check that a DNS entry exists
141 def check_dns_name(d):
142 normalised_name = d.name.rstrip('.') + '.'
144 print "Looking for DNS entry %s as %s" % (d, normalised_name)
146 if opts.use_file is not None:
148 dns_file = open(opts.use_file, "r")
152 for line in dns_file:
154 if line == '' or line[0] == "#":
156 if line.lower() == str(d).lower():
161 ans = resolver.query(normalised_name, d.type)
162 except resolver.NXDOMAIN:
165 # we need to be sure that our IP is there
167 if str(rdata) == str(d.ip):
169 if d.type == 'CNAME':
170 for i in range(len(ans)):
171 if hostname_match(ans[i].target, d.dest):
176 print "Checking %s against %s" % (rdata, d)
177 if hostname_match(rdata.target, d.dest):
178 if str(rdata.port) == str(d.port):
181 d.existing_port = str(rdata.port)
182 d.existing_weight = str(rdata.weight)
184 print "Failed to find DNS entry %s" % d
189 ###########################################
190 # get the list of substitution vars
191 def get_subst_vars():
195 samdb = SamDB(url=lp.get("sam database"), session_info=system_session(),
198 vars['DNSDOMAIN'] = lp.get('realm').lower()
199 vars['HOSTNAME'] = lp.get('netbios name').lower() + "." + vars['DNSDOMAIN']
200 vars['NTDSGUID'] = samdb.get_ntds_GUID()
201 vars['SITE'] = samdb.server_site_name()
202 res = samdb.search(base=None, scope=SCOPE_BASE, attrs=["objectGUID"])
203 guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
204 vars['DOMAINGUID'] = guid
208 ############################################
209 # call nsupdate for an entry
210 def call_nsupdate(d):
211 global ccachename, nsupdate_cmd
214 print "Calling nsupdate for %s" % d
216 if opts.use_file is not None:
217 wfile = open(opts.use_file, 'a')
218 fcntl.lockf(wfile, fcntl.LOCK_EX)
219 wfile.write(str(d)+"\n")
220 fcntl.lockf(wfile, fcntl.LOCK_UN)
223 (tmp_fd, tmpfile) = tempfile.mkstemp()
224 f = os.fdopen(tmp_fd, 'w')
226 f.write("update add %s %u A %s\n" % (d.name, default_ttl, d.ip))
228 if d.existing_port is not None:
229 f.write("update delete %s SRV 0 %s %s %s\n" % (d.name, d.existing_weight,
230 d.existing_port, d.dest))
231 f.write("update add %s %u SRV 0 100 %s %s\n" % (d.name, default_ttl, d.port, d.dest))
232 if d.type == "CNAME":
233 f.write("update add %s %u CNAME %s\n" % (d.name, default_ttl, d.dest))
239 os.putenv("KRB5CCNAME", ccachename)
240 os.system("%s %s" % (nsupdate_cmd, tmpfile))
244 # get the list of DNS entries we should have
245 dns_update_list = lp.private_path('dns_update_list')
247 file = open(dns_update_list, "r")
249 # get the substitution dictionary
250 sub_vars = get_subst_vars()
252 # build up a list of update commands to pass to nsupdate
256 # read each line, and check that the DNS name exists
259 if line == '' or line[0] == "#":
261 d = parse_dns_line(line, sub_vars)
264 # now expand the entries, if any are A record with ip set to $IP
265 # then replace with multiple entries, one for each interface IP
267 if d.type == 'A' and d.ip == "$IP":
269 for i in range(len(IPs)-1):
274 # now check if the entries already exist on the DNS server
276 if not check_dns_name(d):
277 update_list.append(d)
279 if len(update_list) == 0:
281 print "No DNS updates needed"
287 # ask nsupdate to add entries as needed
288 for d in update_list:
291 # delete the ccache if we created it
292 if ccachename is not None:
293 os.unlink(ccachename)