samba-mirror/source4/scripting/bin/samba_dnsupdate

#!/usr/bin/env python
# vim: expandtab
#
# 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 import dsdb
from samba.auth import system_session
from samba.samdb import SamDB
from samba.dcerpc import netlogon, winbind
from samba.netcmd.dns import cmd_dns
from samba import gensec

samba.ensure_third_party_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("--use-samba-tool", action="store_true", help="Use samba-tool to make updates over RPC, rather than over DNS")
parser.add_option("--use-nsupdate", action="store_true", help="Use nsupdate command to make updates over DNS (default, if kinit successful)")
parser.add_option("--all-names", action="store_true")
parser.add_option("--all-interfaces", action="store_true")
parser.add_option("--current-ip", action="append", help="IP address to update DNS to match (helpful if behind NAT, valid multiple times, defaults to values from interfaces=)")
parser.add_option("--rpc-server-ip", type="string", help="IP address of server to use with samba-tool (defaults to first --current-ip)")
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("--update-cache", type="string", help="Cache database of already registered records")
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")
parser.add_option("--no-substitutions", dest='nosubs', action='store_true', help="don't try and expands variables in file specified by --update-list")

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

if opts.current_ip:
    IPs = opts.current_ip
else:
    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)

if opts.rpc_server_ip:
    rpc_server_ip = opts.rpc_server_ip
else:
    rpc_server_ip = IPs[0]

IP6s = []
IP4s = []
for i in IPs:
    if i.find(':') != -1:
        IP6s.append(i)
    else:
        IP4s.append(i)


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


def get_credentials(lp):
    """# get credentials if we haven't got them already."""
    from samba import credentials
    global ccachename
    creds = credentials.Credentials()
    creds.guess(lp)
    creds.set_machine_account(lp)
    creds.set_krb_forwardable(credentials.NO_KRB_FORWARDABLE)
    (tmp_fd, ccachename) = tempfile.mkstemp()
    try:
        creds.get_named_ccache(lp, ccachename)

        if opts.use_file is not None:
            return

        # Now confirm we can get a ticket to a DNS server
        ans = check_one_dns_name(sub_vars['DNSDOMAIN'] + '.', 'NS')
        for i in range(len(ans)):
            target_hostname = str(ans[i].target).rstrip('.')
            settings = {}
            settings["lp_ctx"] = lp
            settings["target_hostname"] = target_hostname

            gensec_client = gensec.Security.start_client(settings)
            gensec_client.set_credentials(creds)
            gensec_client.set_target_service("DNS")
            gensec_client.set_target_hostname(target_hostname)
            gensec_client.want_feature(gensec.FEATURE_SEAL)
            gensec_client.start_mech_by_sasl_name("GSSAPI")
            server_to_client = ""
            try:
                (client_finished, client_to_server) = gensec_client.update(server_to_client)
                if opts.verbose:
                    print "Successfully obtained Kerberos ticket to DNS/%s as %s" \
                            % (target_hostname, creds.get_username())
                return
            except RuntimeError:
                # Only raise an exception if they all failed
                if i != len(ans) - 1:
                    pass
                raise

    except RuntimeError as e:
        os.unlink(ccachename)
        raise e


class dnsobj(object):
    """an object to hold a parsed DNS line"""

    def __init__(self, string_form):
        list = string_form.split()
        if len(list) < 3:
            raise Exception("Invalid DNS entry %r" % string_form)
        self.dest = None
        self.port = None
        self.ip = None
        self.existing_port = None
        self.existing_weight = None
        self.existing_cname_target = None
        self.rpc = False
        self.zone = None
        if list[0] == "RPC":
            self.rpc = True
            self.zone = list[1]
            list = list[2:]
        self.type = list[0]
        self.name = list[1]
        self.nameservers = []
        if self.type == 'SRV':
            if len(list) < 4:
                raise Exception("Invalid DNS entry %r" % string_form)
            self.dest = list[2]
            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]
        elif self.type == 'NS':
            self.dest = list[2]
        else:
            raise Exception("Received unexpected DNS reply of type %s: %s" % (self.type, string_form))

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


def parse_dns_line(line, sub_vars):
    """parse a DNS line from."""
    if line.startswith("SRV _ldap._tcp.pdc._msdcs.") and not samdb.am_pdc():
        # We keep this as compat to the dns_update_list of 4.0/4.1
        if opts.verbose:
            print "Skipping PDC entry (%s) as we are not a PDC" % line
        return None
    subline = samba.substitute_var(line, sub_vars)
    if subline == '' or subline[0] == "#":
        return None
    return dnsobj(subline)


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

def check_one_dns_name(name, name_type, d=None):
    resolv_conf = os.getenv('RESOLV_CONF')
    if not resolv_conf:
        resolv_conf = '/etc/resolv.conf'
    resolver = dns.resolver.Resolver(filename=resolv_conf, configure=True)

    if d is not None and d.nameservers != []:
        resolver.nameservers = d.nameservers
    elif d is not None:
        d.nameservers = resolver.nameservers

    ans = resolver.query(name, name_type)
    return ans

def check_dns_name(d):
    """check that a DNS entry exists."""
    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

    try:
        ans = check_one_dns_name(normalised_name, d.type, d)
    except dns.exception.Timeout:
        raise Exception("Timeout while waiting to contact a working DNS server while looking for %s as %s" % (d, normalised_name))
    except dns.resolver.NoNameservers:
        raise Exception("Unable to contact a working DNS server while looking for %s as %s" % (d, normalised_name))
    except dns.resolver.NXDOMAIN:
        if opts.verbose:
            print "The DNS entry %s, queried as %s does not exist" % (d, normalised_name)
        return False
    except dns.resolver.NoAnswer:
        if opts.verbose:
            print "The DNS entry %s, queried as %s does not hold this record type" % (d, normalised_name)
        return False
    except dns.exception.DNSException:
        raise Exception("Failure while trying to resolve %s as %s" % (d, normalised_name))
    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
    elif d.type == 'CNAME':
        for i in range(len(ans)):
            if hostname_match(ans[i].target, d.dest):
                return True
            else:
                d.existing_cname_target = str(ans[i].target)
    elif d.type == 'NS':
        for i in range(len(ans)):
            if hostname_match(ans[i].target, d.dest):
                return True
    elif 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 "Lookup of %s succeeded, but we failed to find a matching DNS entry for %s" % (normalised_name, d)

    return False


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

    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

    vars['IF_DC'] = ""
    vars['IF_RWDC'] = "# "
    vars['IF_RODC'] = "# "
    vars['IF_PDC'] = "# "
    vars['IF_GC'] = "# "
    vars['IF_RWGC'] = "# "
    vars['IF_ROGC'] = "# "
    vars['IF_DNS_DOMAIN'] = "# "
    vars['IF_RWDNS_DOMAIN'] = "# "
    vars['IF_RODNS_DOMAIN'] = "# "
    vars['IF_DNS_FOREST'] = "# "
    vars['IF_RWDNS_FOREST'] = "# "
    vars['IF_R0DNS_FOREST'] = "# "

    am_rodc = samdb.am_rodc()
    if am_rodc:
        vars['IF_RODC'] = ""
    else:
        vars['IF_RWDC'] = ""

    if samdb.am_pdc():
        vars['IF_PDC'] = ""

    # check if we "are DNS server"
    res = samdb.search(base=samdb.get_config_basedn(),
                   expression='(objectguid=%s)' % vars['NTDSGUID'],
                   attrs=["options", "msDS-hasMasterNCs"])

    if len(res) == 1:
        if "options" in res[0]:
            options = int(res[0]["options"][0])
            if (options & dsdb.DS_NTDSDSA_OPT_IS_GC) != 0:
                vars['IF_GC'] = ""
                if am_rodc:
                    vars['IF_ROGC'] = ""
                else:
                    vars['IF_RWGC'] = ""

        basedn = str(samdb.get_default_basedn())
        forestdn = str(samdb.get_root_basedn())

        if "msDS-hasMasterNCs" in res[0]:
            for e in res[0]["msDS-hasMasterNCs"]:
                if str(e) == "DC=DomainDnsZones,%s" % basedn:
                    vars['IF_DNS_DOMAIN'] = ""
                    if am_rodc:
                        vars['IF_RODNS_DOMAIN'] = ""
                    else:
                        vars['IF_RWDNS_DOMAIN'] = ""
                if str(e) == "DC=ForestDnsZones,%s" % forestdn:
                    vars['IF_DNS_FOREST'] = ""
                    if am_rodc:
                        vars['IF_RODNS_FOREST'] = ""
                    else:
                        vars['IF_RWDNS_FOREST'] = ""

    return vars


def call_nsupdate(d, op="add"):
    """call nsupdate for an entry."""
    global ccachename, nsupdate_cmd, krb5conf

    assert(op in ["add", "delete"])

    if opts.verbose:
        print "Calling nsupdate for %s (%s)" % (d, op)

    if opts.use_file is not None:
        try:
            rfile = open(opts.use_file, 'r+')
        except IOError:
            # Perhaps create it
            rfile = open(opts.use_file, 'w+')
            # Open it for reading again, in case someone else got to it first
            rfile = open(opts.use_file, 'r+')
        fcntl.lockf(rfile, fcntl.LOCK_EX)
        (file_dir, file_name) = os.path.split(opts.use_file)
        (tmp_fd, tmpfile) = tempfile.mkstemp(dir=file_dir, prefix=file_name, suffix="XXXXXX")
        wfile = os.fdopen(tmp_fd, 'a')
        rfile.seek(0)
        for line in rfile:
            if op == "delete":
                l = parse_dns_line(line, {})
                if str(l).lower() == str(d).lower():
                    continue
            wfile.write(line)
        if op == "add":
            wfile.write(str(d)+"\n")
        os.rename(tmpfile, opts.use_file)
        fcntl.lockf(rfile, fcntl.LOCK_UN)
        return

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

    (tmp_fd, tmpfile) = tempfile.mkstemp()
    f = os.fdopen(tmp_fd, 'w')
    if d.nameservers != []:
        f.write('server %s\n' % d.nameservers[0])
    if d.type == "A":
        f.write("update %s %s %u A %s\n" % (op, normalised_name, default_ttl, d.ip))
    if d.type == "AAAA":
        f.write("update %s %s %u AAAA %s\n" % (op, normalised_name, default_ttl, d.ip))
    if d.type == "SRV":
        if op == "add" and 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 %s %s %u SRV 0 100 %s %s\n" % (op, normalised_name, default_ttl, d.port, d.dest))
    if d.type == "CNAME":
        f.write("update %s %s %u CNAME %s\n" % (op, normalised_name, default_ttl, d.dest))
    if d.type == "NS":
        f.write("update %s %s %u NS %s\n" % (op, normalised_name, default_ttl, d.dest))
    if opts.verbose:
        f.write("show\n")
    f.write("send\n")
    f.close()

    # Set a bigger MTU size to work around a bug in nsupdate's doio_send()
    os.environ["SOCKET_WRAPPER_MTU"] = "2000"

    global error_count
    if ccachename:
        os.environ["KRB5CCNAME"] = ccachename
    try:
        cmd = nsupdate_cmd[:]
        cmd.append(tmpfile)
        env = os.environ
        if krb5conf:
            env["KRB5_CONFIG"] = krb5conf
        if ccachename:
            env["KRB5CCNAME"] = ccachename
        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)

    # Let socket_wrapper set the default MTU size
    os.environ["SOCKET_WRAPPER_MTU"] = "0"


def call_samba_tool(d, op="add", zone=None):
    """call samba-tool dns to update an entry."""

    assert(op in ["add", "delete"])

    if (sub_vars['DNSFOREST'] != sub_vars['DNSDOMAIN']) and \
       sub_vars['DNSFOREST'].endswith('.' + sub_vars['DNSDOMAIN']):
        print "Refusing to use samba-tool when forest %s is under domain %s" \
            % (sub_vars['DNSFOREST'], sub_vars['DNSDOMAIN'])

    if opts.verbose:
        print "Calling samba-tool dns for %s (%s)" % (d, op)

    normalised_name = d.name.rstrip('.') + '.'
    if zone is None:
        if normalised_name == (sub_vars['DNSDOMAIN'] + '.'):
            short_name = '@'
            zone = sub_vars['DNSDOMAIN']
        elif normalised_name == (sub_vars['DNSFOREST'] + '.'):
            short_name = '@'
            zone = sub_vars['DNSFOREST']
        elif normalised_name == ('_msdcs.' + sub_vars['DNSFOREST'] + '.'):
            short_name = '@'
            zone = '_msdcs.' + sub_vars['DNSFOREST']
        else:
            if not normalised_name.endswith('.' + sub_vars['DNSDOMAIN'] + '.'):
                print "Not Calling samba-tool dns for %s (%s), %s not in %s" % (d, op, normalised_name, sub_vars['DNSDOMAIN'] + '.')
                return False
            elif normalised_name.endswith('._msdcs.' + sub_vars['DNSFOREST'] + '.'):
                zone = '_msdcs.' + sub_vars['DNSFOREST']
            else:
                zone = sub_vars['DNSDOMAIN']
            len_zone = len(zone)+2
            short_name = normalised_name[:-len_zone]
    else:
        len_zone = len(zone)+2
        short_name = normalised_name[:-len_zone]

    if d.type == "A":
        args = [rpc_server_ip, zone, short_name, "A", d.ip]
    if d.type == "AAAA":
        args = [rpc_server_ip, zone, short_name, "AAAA", d.ip]
    if d.type == "SRV":
        if op == "add" and d.existing_port is not None:
            print "Not handling modify of exising SRV %s using samba-tool" % d
            return False
            op = "update"
            args = [rpc_server_ip, zone, short_name, "SRV",
                    "%s %s %s %s" % (d.existing_weight,
                                     d.existing_port, "0", "100"),
                    "%s %s %s %s" % (d.dest, d.port, "0", "100")]
        else:
            args = [rpc_server_ip, zone, short_name, "SRV", "%s %s %s %s" % (d.dest, d.port, "0", "100")]
    if d.type == "CNAME":
        if d.existing_cname_target is None:
            args = [rpc_server_ip, zone, short_name, "CNAME", d.dest]
        else:
            op = "update"
            args = [rpc_server_ip, zone, short_name, "CNAME",
                    d.existing_cname_target.rstrip('.'), d.dest]

    if d.type == "NS":
        args = [rpc_server_ip, zone, short_name, "NS", d.dest]

    global error_count
    try:
        cmd = cmd_dns()
        if opts.verbose:
            print "Calling samba-tool dns %s -k no -P %s" % (op, args)
        ret = cmd._run("dns", op, "-k", "no", "-P", *args)
        if ret == -1:
            if opts.fail_immediately:
                sys.exit(1)
            error_count = error_count + 1
            if opts.verbose:
                print("Failed 'samba-tool dns' based update: %s : %s" % (str(d), estr))
    except Exception, estr:
        raise
        if opts.fail_immediately:
            sys.exit(1)
        error_count = error_count + 1
        if opts.verbose:
            print("Failed 'samba-tool dns' based update: %s : %s" % (str(d), estr))

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

    assert(op in ["add", "delete"])

    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)
    if op == "add":
        name.dns_register = True
    else:
        name.dns_register = False
    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, op="add"):
    '''RODCs need to use the netlogon API for nsupdate'''
    global lp, sub_vars

    assert(op in ["add", "delete"])

    # 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, op)
            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')

if opts.update_cache:
    dns_update_cache = opts.update_cache
else:
    dns_update_cache = lp.private_path('dns_update_cache')

# 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")

if opts.nosubs:
    sub_vars = {}
else:
    samdb = SamDB(url=lp.samdb_url(), session_info=system_session(), lp=lp)

    # get the substitution dictionary
    sub_vars = get_subst_vars(samdb)

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

dup_set = set()
cache_set = set()

rebuild_cache = False
try:
    cfile = open(dns_update_cache, 'r+')
except IOError:
    # Perhaps create it
    cfile = open(dns_update_cache, 'w+')
    # Open it for reading again, in case someone else got to it first
    cfile = open(dns_update_cache, 'r+')
fcntl.lockf(cfile, fcntl.LOCK_EX)
for line in cfile:
    line = line.strip()
    if line == '' or line[0] == "#":
        continue
    c = parse_dns_line(line, {})
    if c is None:
        continue
    if str(c) not in cache_set:
        cache_list.append(c)
        cache_set.add(str(c))

# 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 is None:
        continue
    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:
    found = False
    for c in cache_list:
        if str(c).lower() == str(d).lower():
            found = True
            break
    if not found:
        rebuild_cache = True
    if opts.all_names:
        update_list.append(d)
        if opts.verbose:
            print "force update: %s" % d
    elif not check_dns_name(d):
        update_list.append(d)
        if opts.verbose:
            print "need update: %s" % d


for c in cache_list:
    found = False
    for d in dns_list:
        if str(c).lower() == str(d).lower():
            found = True
            break
    if found:
        continue
    rebuild_cache = True
    if not opts.all_names and not check_dns_name(c):
        continue
    delete_list.append(c)
    if opts.verbose:
        print "need delete: %s" % c

if len(delete_list) == 0 and len(update_list) == 0 and not rebuild_cache:
    if opts.verbose:
        print "No DNS updates needed"
    sys.exit(0)
else:
    if opts.verbose:
        print "%d DNS updates and %d DNS deletes needed" % (len(update_list), len(delete_list))

use_samba_tool = opts.use_samba_tool
use_nsupdate = opts.use_nsupdate
# get our krb5 creds
if len(delete_list) != 0 or len(update_list) != 0 and not opts.nocreds:
    try:
        creds = get_credentials(lp)
    except RuntimeError as e:
        ccachename = None

        if sub_vars['IF_RWDNS_DOMAIN'] == "# ":
            raise

        if use_nsupdate:
            raise

        print "Failed to get Kerberos credentials, falling back to samba-tool: %s" % e
        use_samba_tool = True


# ask nsupdate to delete entries as needed
for d in delete_list:
    if d.rpc or (not use_nsupdate and use_samba_tool):
        if opts.verbose:
            print "update (samba-tool): %s" % d
        call_samba_tool(d, op="delete", zone=d.zone)

    elif am_rodc:
        if d.name.lower() == domain.lower():
            if opts.verbose:
                print "skip delete (rodc): %s" % d
            continue
        if not d.type in [ 'A', 'AAAA' ]:
            if opts.verbose:
                print "delete (rodc): %s" % d
            call_rodc_update(d, op="delete")
        else:
            if opts.verbose:
                print "delete (nsupdate): %s" % d
            call_nsupdate(d, op="delete")
    else:
        if opts.verbose:
            print "delete (nsupdate): %s" % d
        call_nsupdate(d, op="delete")

# ask nsupdate to add entries as needed
for d in update_list:
    if d.rpc or (not use_nsupdate and use_samba_tool):
        if opts.verbose:
            print "update (samba-tool): %s" % d
        call_samba_tool(d, zone=d.zone)

    elif am_rodc:
        if d.name.lower() == domain.lower():
            if opts.verbose:
                print "skip (rodc): %s" % d
            continue
        if not d.type in [ 'A', 'AAAA' ]:
            if opts.verbose:
                print "update (rodc): %s" % d
            call_rodc_update(d)
        else:
            if opts.verbose:
                print "update (nsupdate): %s" % d
            call_nsupdate(d)
    else:
        if opts.verbose:
            print "update(nsupdate): %s" % d
        call_nsupdate(d)

if rebuild_cache:
    print "Rebuilding cache at %s" % dns_update_cache
    (file_dir, file_name) = os.path.split(dns_update_cache)
    (tmp_fd, tmpfile) = tempfile.mkstemp(dir=file_dir, prefix=file_name, suffix="XXXXXX")
    wfile = os.fdopen(tmp_fd, 'a')
    for d in dns_list:
        if opts.verbose:
            print "Adding %s to %s" % (str(d), file_name)
        wfile.write(str(d)+"\n")
    os.rename(tmpfile, dns_update_cache)
fcntl.lockf(cfile, fcntl.LOCK_UN)

# 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)