+from samba.samdb import SamDB
+
+default_ttl = 900
+
+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")
+
+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")
+IPs = glue.interface_ips(lp)
+nsupdate_cmd = lp.get('nsupdate command')
+
+if len(IPs) == 0:
+ print "No IP interfaces - skipping DNS updates"
+ sys.exit(0)
+
+
+
+########################################################
+# get credentials if we haven't got them already
+def get_credentials(lp):
+ from samba.credentials import Credentials
+ global ccachename, creds
+ if creds is not None:
+ return
+ creds = Credentials()
+ creds.guess(lp)
+ try:
+ creds.set_machine_account(lp)
+ except:
+ print "Failed to set machine account"
+ raise
+
+ (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):
+ self.type = None
+ self.name = None
+ self.dest = None
+ self.port = None
+ self.ip = None
+ def __str__(self):
+ if d.type == "A": 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)
+
+
+################################################
+# parse a DNS line from
+def parse_dns_line(line, sub_vars):
+ d = dnsobj()
+ subline = samba.substitute_var(line, sub_vars)
+ list = subline.split()
+ d.type = list[0]
+ d.name = list[1]
+ if d.type == 'SRV':
+ d.dest = list[2]
+ d.port = list[3]
+ elif d.type == 'A':
+ d.ip = list[2] # usually $IP, which gets replaced
+ elif d.type == 'CNAME':
+ d.dest = list[2]
+ else:
+ print "Received unexpected DNS reply of type %s" % d.type
+ raise
+ 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):
+ if opts.verbose:
+ print "Looking for DNS entry %s" % d
+ try:
+ ans = dns.resolver.query(d.name, d.type)
+ except dns.resolver.NXDOMAIN:
+ return False
+ if d.type == 'A':
+ # 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 == 'SRV':
+ if opts.verbose:
+ print "Got %u replies in SRV lookup for %s" % (len(ans), d.name)
+ for i in range(len(ans)):
+ rdata = ans[i]
+ if opts.verbose:
+ print "Checking %s against %s" % (rdata, d)
+ if str(rdata.port) == str(d.port) and hostname_match(rdata.target, d.dest):
+ return True
+ if opts.verbose:
+ print "Failed to find DNS entry %s" % d
+ return False
+
+
+###########################################
+# get the list of substitution vars
+def get_subst_vars():
+ global lp
+ vars = {}
+
+ samdb = SamDB(url=lp.get("sam database"), session_info=system_session(), lp=lp)
+
+ vars['DNSDOMAIN'] = lp.get('realm').lower()
+ vars['HOSTNAME'] = lp.get('netbios name').lower() + "." + vars['DNSDOMAIN']
+ vars['NTDSGUID'] = samdb.get_ntds_GUID()
+ vars['SITE'] = samdb.server_site_name()
+ res = samdb.search(base=None, scope=SCOPE_BASE, attrs=["objectGUID"])
+ guid = samdb.schema_format_value("objectGUID", res[0]['objectGUID'][0])
+ vars['DOMAINGUID'] = guid
+ return vars
+
+
+############################################
+# call nsupdate for an entry
+def call_nsupdate(d):
+ global ccachename, nsupdate_cmd
+
+ if opts.verbose:
+ print "Calling nsupdate for %s" % d
+ (tmp_fd, tmpfile) = tempfile.mkstemp()
+ f = os.fdopen(tmp_fd, 'w')
+ if d.type == "A":
+ f.write("update add %s %u A %s\n" % (d.name, default_ttl, d.ip))
+ if d.type == "SRV":
+ f.write("update add %s %u SRV 0 100 %s %s\n" % (d.name, default_ttl, d.port, d.dest))
+ if d.type == "CNAME":
+ f.write("update add %s %u SRV %s\n" % (d.name, default_ttl, d.dest))
+ if opts.verbose:
+ f.write("show\n")
+ f.write("send\n")
+ f.close()
+
+ os.putenv("KRB5CCNAME", ccachename)
+ os.system("%s %s" % (nsupdate_cmd, tmpfile))
+ os.unlink(tmpfile)
+
+
+# get the list of DNS entries we should have
+dns_update_list = lp.private_path('dns_update_list')
+
+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 = []
+
+# read each line, and check that the DNS name exists
+line = file.readline()
+while line:
+ line = line.rstrip().lstrip()
+ if line[0] == "#":
+ line = file.readline()
+ continue
+ d = parse_dns_line(line, sub_vars)
+ dns_list.append(d)
+ line = file.readline()
+
+# now expand the entries, if any are A record with ip set to $IP
+# then replace with multiple entries, one for each interface IP
+for d in dns_list:
+ if d.type == 'A' and d.ip == "$IP":
+ d.ip = IPs[0]
+ for i in range(len(IPs)-1):
+ d2 = d
+ d2.ip = IPs[i+1]
+ dns_list.append(d2)
+
+# now check if the entries already exist on the DNS server
+for d in dns_list:
+ if 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
+get_credentials(lp)
+
+# ask nsupdate to add entries as needed
+for d in update_list:
+ call_nsupdate(d)
+
+# delete the ccache if we created it
+if ccachename is not None:
+ os.unlink(ccachename)
+
git.samba.org / samba.git / commitdiff