# backend code for upgrading from Samba3
# Copyright Jelmer Vernooij 2005-2007
# Copyright Andrew Bartlett 2011
#
# 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/>.
#

"""Support code for upgrading from Samba 3 to Samba 4."""

__docformat__ = "restructuredText"

import ldb
import time
import pwd

from samba import Ldb, registry
from samba.param import LoadParm
from samba.provision import provision, ProvisioningError, setsysvolacl
from samba.provision.common import FILL_FULL
from samba.samba3 import passdb
from samba.samba3 import param as s3param
from samba.dcerpc import lsa, samr, security
from samba.dcerpc.security import dom_sid
from samba.credentials import Credentials
from samba import dsdb
from samba.ndr import ndr_pack
from samba import unix2nttime
from samba import generate_random_password


def import_sam_policy(samdb, policy, logger):
    """Import a Samba 3 policy.

    :param samdb: Samba4 SAM database
    :param policy: Samba3 account policy
    :param logger: Logger object
    """

    # Following entries are used -
    #    min password length, password history, minimum password age,
    #    maximum password age, lockout duration
    #
    # Following entries are not used -
    #    reset count minutes, user must logon to change password,
    #    bad lockout minutes, disconnect time

    m = ldb.Message()
    m.dn = samdb.get_default_basedn()

    if 'min password length' in policy:
        m['a01'] = ldb.MessageElement(str(policy['min password length']),
                                      ldb.FLAG_MOD_REPLACE, 'minPwdLength')

    if 'password history' in policy:
        m['a02'] = ldb.MessageElement(str(policy['password history']),
                                      ldb.FLAG_MOD_REPLACE, 'pwdHistoryLength')

    if 'minimum password age' in policy:
        min_pw_age_unix = policy['minimum password age']
        min_pw_age_nt = int(-min_pw_age_unix * (1e7))
        m['a03'] = ldb.MessageElement(str(min_pw_age_nt), ldb.FLAG_MOD_REPLACE,
                                      'minPwdAge')

    if 'maximum password age' in policy:
        max_pw_age_unix = policy['maximum password age']
        if max_pw_age_unix == -1 or max_pw_age_unix == 0:
            max_pw_age_nt = -0x8000000000000000
        else:
            max_pw_age_nt = int(-max_pw_age_unix * (1e7))

        m['a04'] = ldb.MessageElement(str(max_pw_age_nt), ldb.FLAG_MOD_REPLACE,
                                      'maxPwdAge')

    if 'lockout duration' in policy:
        lockout_duration_mins = policy['lockout duration']
        lockout_duration_nt = unix2nttime(lockout_duration_mins * 60)

        m['a05'] = ldb.MessageElement(str(lockout_duration_nt),
                                      ldb.FLAG_MOD_REPLACE, 'lockoutDuration')

    try:
        samdb.modify(m)
    except ldb.LdbError as e:
        logger.warn("Could not set account policy, (%s)", str(e))


def add_posix_attrs(logger, samdb, sid, name, nisdomain, xid_type, home=None,
                    shell=None, pgid=None):
    """Add posix attributes for the user/group

    :param samdb: Samba4 sam.ldb database
    :param sid: user/group sid
    :param sid: user/group name
    :param nisdomain: name of the (fake) NIS domain
    :param xid_type: type of id (ID_TYPE_UID/ID_TYPE_GID)
    :param home: user homedir (Unix homepath)
    :param shell: user shell
    :param pgid: users primary group id
    """

    try:
        m = ldb.Message()
        m.dn = ldb.Dn(samdb, "<SID=%s>" % str(sid))
        if xid_type == "ID_TYPE_UID":
            m['unixHomeDirectory'] = ldb.MessageElement(
                str(home), ldb.FLAG_MOD_REPLACE, 'unixHomeDirectory')
            m['loginShell'] = ldb.MessageElement(
                str(shell), ldb.FLAG_MOD_REPLACE, 'loginShell')
            m['gidNumber'] = ldb.MessageElement(
                str(pgid), ldb.FLAG_MOD_REPLACE, 'gidNumber')

        m['msSFU30NisDomain'] = ldb.MessageElement(
            str(nisdomain), ldb.FLAG_MOD_REPLACE, 'msSFU30NisDomain')

        samdb.modify(m)
    except ldb.LdbError as e:
        logger.warn(
            'Could not add posix attrs for AD entry for sid=%s, (%s)',
            str(sid), str(e))


def add_ad_posix_idmap_entry(samdb, sid, xid, xid_type, logger):
    """Create idmap entry

    :param samdb: Samba4 sam.ldb database
    :param sid: user/group sid
    :param xid: user/group id
    :param xid_type: type of id (ID_TYPE_UID/ID_TYPE_GID)
    :param logger: Logger object
    """

    try:
        m = ldb.Message()
        m.dn = ldb.Dn(samdb, "<SID=%s>" % str(sid))
        if xid_type == "ID_TYPE_UID":
            m['uidNumber'] = ldb.MessageElement(
                str(xid), ldb.FLAG_MOD_REPLACE, 'uidNumber')
            m['objectClass'] = ldb.MessageElement(
                "posixAccount", ldb.FLAG_MOD_ADD, 'objectClass')
        elif xid_type == "ID_TYPE_GID":
            m['gidNumber'] = ldb.MessageElement(
                str(xid), ldb.FLAG_MOD_REPLACE, 'gidNumber')
            m['objectClass'] = ldb.MessageElement(
                "posixGroup", ldb.FLAG_MOD_ADD, 'objectClass')

        samdb.modify(m)
    except ldb.LdbError as e:
        logger.warn(
            'Could not modify AD idmap entry for sid=%s, id=%s, type=%s (%s)',
            str(sid), str(xid), xid_type, str(e))


def add_idmap_entry(idmapdb, sid, xid, xid_type, logger):
    """Create idmap entry

    :param idmapdb: Samba4 IDMAP database
    :param sid: user/group sid
    :param xid: user/group id
    :param xid_type: type of id (ID_TYPE_UID/ID_TYPE_GID)
    :param logger: Logger object
    """

    # First try to see if we already have this entry
    found = False
    msg = idmapdb.search(expression='objectSid=%s' % str(sid))
    if msg.count == 1:
        found = True

    if found:
        try:
            m = ldb.Message()
            m.dn = msg[0]['dn']
            m['xidNumber'] = ldb.MessageElement(
                str(xid), ldb.FLAG_MOD_REPLACE, 'xidNumber')
            m['type'] = ldb.MessageElement(
                xid_type, ldb.FLAG_MOD_REPLACE, 'type')
            idmapdb.modify(m)
        except ldb.LdbError as e:
            logger.warn(
                'Could not modify idmap entry for sid=%s, id=%s, type=%s (%s)',
                str(sid), str(xid), xid_type, str(e))
    else:
        try:
            idmapdb.add({"dn": "CN=%s" % str(sid),
                         "cn": str(sid),
                         "objectClass": "sidMap",
                         "objectSid": ndr_pack(sid),
                         "type": xid_type,
                         "xidNumber": str(xid)})
        except ldb.LdbError as e:
            logger.warn(
                'Could not add idmap entry for sid=%s, id=%s, type=%s (%s)',
                str(sid), str(xid), xid_type, str(e))


def import_idmap(idmapdb, samba3, logger):
    """Import idmap data.

    :param idmapdb: Samba4 IDMAP database
    :param samba3_idmap: Samba3 IDMAP database to import from
    :param logger: Logger object
    """

    try:
        samba3_idmap = samba3.get_idmap_db()
    except IOError as e:
        logger.warn('Cannot open idmap database, Ignoring: %s', str(e))
        return

    currentxid = max(samba3_idmap.get_user_hwm(), samba3_idmap.get_group_hwm())
    lowerbound = currentxid
    # FIXME: upperbound

    m = ldb.Message()
    m.dn = ldb.Dn(idmapdb, 'CN=CONFIG')
    m['lowerbound'] = ldb.MessageElement(
        str(lowerbound), ldb.FLAG_MOD_REPLACE, 'lowerBound')
    m['xidNumber'] = ldb.MessageElement(
        str(currentxid), ldb.FLAG_MOD_REPLACE, 'xidNumber')
    idmapdb.modify(m)

    for id_type, xid in samba3_idmap.ids():
        if id_type == 'UID':
            xid_type = 'ID_TYPE_UID'
        elif id_type == 'GID':
            xid_type = 'ID_TYPE_GID'
        else:
            logger.warn('Wrong type of entry in idmap (%s), Ignoring', id_type)
            continue

        sid = samba3_idmap.get_sid(xid, id_type)
        add_idmap_entry(idmapdb, dom_sid(sid), xid, xid_type, logger)


def add_group_from_mapping_entry(samdb, groupmap, logger):
    """Add or modify group from group mapping entry

    param samdb: Samba4 SAM database
    param groupmap: Groupmap entry
    param logger: Logger object
    """

    # First try to see if we already have this entry
    try:
        msg = samdb.search(
            base='<SID=%s>' % str(groupmap.sid), scope=ldb.SCOPE_BASE)
        found = True
    except ldb.LdbError as e1:
        (ecode, emsg) = e1.args
        if ecode == ldb.ERR_NO_SUCH_OBJECT:
            found = False
        else:
            raise ldb.LdbError(ecode, emsg)

    if found:
        logger.warn('Group already exists sid=%s, groupname=%s existing_groupname=%s, Ignoring.',
                    str(groupmap.sid), groupmap.nt_name, msg[0]['sAMAccountName'][0])
    else:
        if groupmap.sid_name_use == lsa.SID_NAME_WKN_GRP:
            # In a lot of Samba3 databases, aliases are marked as well known groups
            (group_dom_sid, rid) = groupmap.sid.split()
            if (group_dom_sid != security.dom_sid(security.SID_BUILTIN)):
                return

        m = ldb.Message()
        # We avoid using the format string to avoid needing to escape the CN values
        m.dn = ldb.Dn(samdb, "CN=X,CN=Users")
        m.dn.set_component(0, "CN", groupmap.nt_name)
        m.dn.add_base(samdb.get_default_basedn())
        m['objectClass'] = ldb.MessageElement('group', ldb.FLAG_MOD_ADD, 'objectClass')
        m['objectSid'] = ldb.MessageElement(ndr_pack(groupmap.sid), ldb.FLAG_MOD_ADD,
                                            'objectSid')
        m['sAMAccountName'] = ldb.MessageElement(groupmap.nt_name, ldb.FLAG_MOD_ADD,
                                                 'sAMAccountName')

        if groupmap.comment:
            m['description'] = ldb.MessageElement(groupmap.comment, ldb.FLAG_MOD_ADD,
                                                  'description')

        # Fix up incorrect 'well known' groups that are actually builtin (per test above) to be aliases
        if groupmap.sid_name_use == lsa.SID_NAME_ALIAS or groupmap.sid_name_use == lsa.SID_NAME_WKN_GRP:
            m['groupType'] = ldb.MessageElement(str(dsdb.GTYPE_SECURITY_DOMAIN_LOCAL_GROUP),
                                                ldb.FLAG_MOD_ADD, 'groupType')

        try:
            samdb.add(m, controls=["relax:0"])
        except ldb.LdbError as e:
            logger.warn('Could not add group name=%s (%s)', groupmap.nt_name, str(e))


def add_users_to_group(samdb, group, members, logger):
    """Add user/member to group/alias

    param samdb: Samba4 SAM database
    param group: Groupmap object
    param members: List of member SIDs
    param logger: Logger object
    """
    for member_sid in members:
        m = ldb.Message()
        m.dn = ldb.Dn(samdb, "<SID=%s>" % str(group.sid))
        m['a01'] = ldb.MessageElement("<SID=%s>" % str(member_sid), ldb.FLAG_MOD_ADD, 'member')

        try:
            samdb.modify(m)
        except ldb.LdbError as e:
            (ecode, emsg) = e.args
            if ecode == ldb.ERR_ENTRY_ALREADY_EXISTS:
                logger.debug("skipped re-adding member '%s' to group '%s': %s", member_sid, group.sid, emsg)
            elif ecode == ldb.ERR_NO_SUCH_OBJECT:
                raise ProvisioningError("Could not add member '%s' to group '%s' as either group or user record doesn't exist: %s" % (member_sid, group.sid, emsg))
            else:
                raise ProvisioningError("Could not add member '%s' to group '%s': %s" % (member_sid, group.sid, emsg))


def import_wins(samba4_winsdb, samba3_winsdb):
    """Import settings from a Samba3 WINS database.

    :param samba4_winsdb: WINS database to import to
    :param samba3_winsdb: WINS database to import from
    """

    version_id = 0

    for (name, (ttl, ips, nb_flags)) in samba3_winsdb.items():
        version_id += 1

        type = int(name.split("#", 1)[1], 16)

        if type == 0x1C:
            rType = 0x2
        elif type & 0x80:
            if len(ips) > 1:
                rType = 0x2
            else:
                rType = 0x1
        else:
            if len(ips) > 1:
                rType = 0x3
            else:
                rType = 0x0

        if ttl > time.time():
            rState = 0x0  # active
        else:
            rState = 0x1  # released

        nType = ((nb_flags & 0x60) >> 5)

        samba4_winsdb.add({"dn": "name=%s,type=0x%s" % tuple(name.split("#")),
                           "type": name.split("#")[1],
                           "name": name.split("#")[0],
                           "objectClass": "winsRecord",
                           "recordType": str(rType),
                           "recordState": str(rState),
                           "nodeType": str(nType),
                           "expireTime": ldb.timestring(ttl),
                           "isStatic": "0",
                           "versionID": str(version_id),
                           "address": ips})

    samba4_winsdb.add({"dn": "cn=VERSION",
                       "cn": "VERSION",
                       "objectClass": "winsMaxVersion",
                       "maxVersion": str(version_id)})


SAMBA3_PREDEF_NAMES = {
        'HKLM': registry.HKEY_LOCAL_MACHINE,
}


def import_registry(samba4_registry, samba3_regdb):
    """Import a Samba 3 registry database into the Samba 4 registry.

    :param samba4_registry: Samba 4 registry handle.
    :param samba3_regdb: Samba 3 registry database handle.
    """
    def ensure_key_exists(keypath):
        (predef_name, keypath) = keypath.split("/", 1)
        predef_id = SAMBA3_PREDEF_NAMES[predef_name]
        keypath = keypath.replace("/", "\\")
        return samba4_registry.create_key(predef_id, keypath)

    for key in samba3_regdb.keys():
        key_handle = ensure_key_exists(key)
        for subkey in samba3_regdb.subkeys(key):
            ensure_key_exists(subkey)
        for (value_name, (value_type, value_data)) in samba3_regdb.values(key).items():
            key_handle.set_value(value_name, value_type, value_data)


def get_posix_attr_from_ldap_backend(logger, ldb_object, base_dn, user, attr):
    """Get posix attributes from a samba3 ldap backend
    :param ldbs: a list of ldb connection objects
    :param base_dn: the base_dn of the connection
    :param user: the user to get the attribute for
    :param attr: the attribute to be retrieved
    """
    try:
        msg = ldb_object.search(base_dn, scope=ldb.SCOPE_SUBTREE,
                                expression=("(&(objectClass=posixAccount)(uid=%s))"
                                            % (user)), attrs=[attr])
    except ldb.LdbError as e:
        raise ProvisioningError("Failed to retrieve attribute %s for user %s, the error is: %s" % (attr, user, e))
    else:
        if msg.count <= 1:
            # This will raise KeyError (which is what we want) if there isn't a entry for this user
            return msg[0][attr][0]
        else:
            logger.warning("LDAP entry for user %s contains more than one %s", user, attr)
            raise KeyError


def upgrade_from_samba3(samba3, logger, targetdir, session_info=None,
                        useeadb=False, dns_backend=None, use_ntvfs=False):
    """Upgrade from samba3 database to samba4 AD database

    :param samba3: samba3 object
    :param logger: Logger object
    :param targetdir: samba4 database directory
    :param session_info: Session information
    """
    serverrole = samba3.lp.server_role()

    domainname = samba3.lp.get("workgroup")
    realm = samba3.lp.get("realm")
    netbiosname = samba3.lp.get("netbios name")

    if samba3.lp.get("ldapsam:trusted") is None:
        samba3.lp.set("ldapsam:trusted", "yes")

    # secrets db
    try:
        secrets_db = samba3.get_secrets_db()
    except IOError as e:
        raise ProvisioningError("Could not open '%s', the Samba3 secrets database: %s.  Perhaps you specified the incorrect smb.conf, --testparm or --dbdir option?" % (samba3.privatedir_path("secrets.tdb"), str(e)))

    if not domainname:
        domainname = secrets_db.domains()[0]
        logger.warning("No workgroup specified in smb.conf file, assuming '%s'",
                       domainname)

    if not realm:
        if serverrole == "ROLE_DOMAIN_BDC" or serverrole == "ROLE_DOMAIN_PDC":
            raise ProvisioningError("No realm specified in smb.conf file and being a DC. That upgrade path doesn't work! Please add a 'realm' directive to your old smb.conf to let us know which one you want to use (it is the DNS name of the AD domain you wish to create.")
        else:
            realm = domainname.upper()
            logger.warning("No realm specified in smb.conf file, assuming '%s'",
                           realm)

    # Find machine account and password
    next_rid = 1000

    try:
        machinepass = secrets_db.get_machine_password(netbiosname)
    except KeyError:
        machinepass = None

    if samba3.lp.get("passdb backend").split(":")[0].strip() == "ldapsam":
        base_dn = samba3.lp.get("ldap suffix")
        ldapuser = samba3.lp.get("ldap admin dn")
        ldappass = secrets_db.get_ldap_bind_pw(ldapuser)
        if ldappass is None:
            raise ProvisioningError("ldapsam passdb backend detected but no LDAP Bind PW found in secrets.tdb for user %s.  Please point this tool at the secrets.tdb that was used by the previous installation.")
        ldappass = ldappass.strip('\x00')
        ldap = True
    else:
        ldapuser = None
        ldappass = None
        ldap = False

    # We must close the direct pytdb database before the C code loads it
    secrets_db.close()

    # Connect to old password backend
    passdb.set_secrets_dir(samba3.lp.get("private dir"))
    s3db = samba3.get_sam_db()

    # Get domain sid
    try:
        domainsid = passdb.get_global_sam_sid()
    except passdb.error:
        raise Exception("Can't find domain sid for '%s', Exiting." % domainname)

    # Get machine account, sid, rid
    try:
        machineacct = s3db.getsampwnam('%s$' % netbiosname)
    except passdb.error:
        machinerid = None
        machinesid = None
    else:
        machinesid, machinerid = machineacct.user_sid.split()

    # Export account policy
    logger.info("Exporting account policy")
    policy = s3db.get_account_policy()

    # Export groups from old passdb backend
    logger.info("Exporting groups")
    grouplist = s3db.enum_group_mapping()
    groupmembers = {}
    for group in grouplist:
        sid, rid = group.sid.split()
        if sid == domainsid:
            if rid >= next_rid:
                next_rid = rid + 1

        # Get members for each group/alias
        if group.sid_name_use == lsa.SID_NAME_ALIAS:
            try:
                members = s3db.enum_aliasmem(group.sid)
                groupmembers[str(group.sid)] = members
            except passdb.error as e:
                logger.warn("Ignoring group '%s' %s listed but then not found: %s",
                            group.nt_name, group.sid, e)
                continue
        elif group.sid_name_use == lsa.SID_NAME_DOM_GRP:
            try:
                members = s3db.enum_group_members(group.sid)
                groupmembers[str(group.sid)] = members
            except passdb.error as e:
                logger.warn("Ignoring group '%s' %s listed but then not found: %s",
                            group.nt_name, group.sid, e)
                continue
        elif group.sid_name_use == lsa.SID_NAME_WKN_GRP:
            (group_dom_sid, rid) = group.sid.split()
            if (group_dom_sid != security.dom_sid(security.SID_BUILTIN)):
                logger.warn("Ignoring 'well known' group '%s' (should already be in AD, and have no members)",
                            group.nt_name)
                continue
            # A number of buggy databases mix up well known groups and aliases.
            try:
                members = s3db.enum_aliasmem(group.sid)
                groupmembers[str(group.sid)] = members
            except passdb.error as e:
                logger.warn("Ignoring group '%s' %s listed but then not found: %s",
                            group.nt_name, group.sid, e)
                continue
        else:
            logger.warn("Ignoring group '%s' %s with sid_name_use=%d",
                        group.nt_name, group.sid, group.sid_name_use)
            continue

    # Export users from old passdb backend
    logger.info("Exporting users")
    userlist = s3db.search_users(0)
    userdata = {}
    uids = {}
    admin_user = None
    for entry in userlist:
        if machinerid and machinerid == entry['rid']:
            continue
        username = entry['account_name']
        if entry['rid'] < 1000:
            logger.info("  Skipping wellknown rid=%d (for username=%s)", entry['rid'], username)
            continue
        if entry['rid'] >= next_rid:
            next_rid = entry['rid'] + 1

        user = s3db.getsampwnam(username)
        acct_type = (user.acct_ctrl & (samr.ACB_NORMAL |
                                       samr.ACB_WSTRUST |
                                       samr.ACB_SVRTRUST |
                                       samr.ACB_DOMTRUST))
        if acct_type == samr.ACB_SVRTRUST:
            logger.warn("  Demoting BDC account trust for %s, this DC must be elevated to an AD DC using 'samba-tool domain dcpromo'" % username[:-1])
            user.acct_ctrl = (user.acct_ctrl & ~samr.ACB_SVRTRUST) | samr.ACB_WSTRUST

        elif acct_type == samr.ACB_DOMTRUST:
            logger.warn("  Skipping inter-domain trust from domain %s, this trust must be re-created as an AD trust" % username[:-1])
            continue

        elif acct_type == (samr.ACB_WSTRUST) and username[-1] != '$':
            logger.warn("  Skipping account %s that has ACB_WSTRUST (W) set but does not end in $.  This account can not have worked, and is probably left over from a misconfiguration." % username)
            continue

        elif acct_type == (samr.ACB_NORMAL | samr.ACB_WSTRUST) and username[-1] == '$':
            logger.warn("  Fixing account %s which had both ACB_NORMAL (U) and ACB_WSTRUST (W) set.  Account will be marked as ACB_WSTRUST (W), i.e. as a domain member" % username)
            user.acct_ctrl = (user.acct_ctrl & ~samr.ACB_NORMAL)

        elif acct_type == (samr.ACB_NORMAL | samr.ACB_SVRTRUST) and username[-1] == '$':
            logger.warn("  Fixing account %s which had both ACB_NORMAL (U) and ACB_SVRTRUST (S) set.  Account will be marked as ACB_WSTRUST (S), i.e. as a domain member" % username)
            user.acct_ctrl = (user.acct_ctrl & ~samr.ACB_NORMAL)

        elif acct_type == 0 and username[-1] != '$':
            user.acct_ctrl = (user.acct_ctrl | samr.ACB_NORMAL)

        elif (acct_type == samr.ACB_NORMAL or acct_type == samr.ACB_WSTRUST):
            pass

        else:
            raise ProvisioningError("""Failed to upgrade due to invalid account %s, account control flags 0x%08X must have exactly one of
ACB_NORMAL (N, 0x%08X), ACB_WSTRUST (W 0x%08X), ACB_SVRTRUST (S 0x%08X) or ACB_DOMTRUST (D 0x%08X).

Please fix this account before attempting to upgrade again
"""
                                    % (username, user.acct_ctrl,
                                       samr.ACB_NORMAL, samr.ACB_WSTRUST, samr.ACB_SVRTRUST, samr.ACB_DOMTRUST))

        userdata[username] = user
        try:
            uids[username] = s3db.sid_to_id(user.user_sid)[0]
        except passdb.error:
            try:
                uids[username] = pwd.getpwnam(username).pw_uid
            except KeyError:
                pass

        if not admin_user and username.lower() == 'root':
            admin_user = username
        if username.lower() == 'administrator':
            admin_user = username

        try:
            group_memberships = s3db.enum_group_memberships(user)
            for group in group_memberships:
                if str(group) in groupmembers:
                    if user.user_sid not in groupmembers[str(group)]:
                        groupmembers[str(group)].append(user.user_sid)
                else:
                    groupmembers[str(group)] = [user.user_sid]
        except passdb.error as e:
            logger.warn("Ignoring group memberships of '%s' %s: %s",
                        username, user.user_sid, e)

    logger.info("Next rid = %d", next_rid)

    # Check for same username/groupname
    group_names = set([g.nt_name for g in grouplist])
    user_names = set([u['account_name'] for u in userlist])
    common_names = group_names.intersection(user_names)
    if common_names:
        logger.error("Following names are both user names and group names:")
        for name in common_names:
            logger.error("   %s" % name)
        raise ProvisioningError("Please remove common user/group names before upgrade.")

    # Check for same user sid/group sid
    group_sids = set([str(g.sid) for g in grouplist])
    if len(grouplist) != len(group_sids):
        raise ProvisioningError("Please remove duplicate group sid entries before upgrade.")
    user_sids = set(["%s-%u" % (domainsid, u['rid']) for u in userlist])
    if len(userlist) != len(user_sids):
        raise ProvisioningError("Please remove duplicate user sid entries before upgrade.")
    common_sids = group_sids.intersection(user_sids)
    if common_sids:
        logger.error("Following sids are both user and group sids:")
        for sid in common_sids:
            logger.error("   %s" % str(sid))
        raise ProvisioningError("Please remove duplicate sid entries before upgrade.")

    # Get posix attributes from ldap or the os
    homes = {}
    shells = {}
    pgids = {}
    if ldap:
        creds = Credentials()
        creds.guess(samba3.lp)
        creds.set_bind_dn(ldapuser)
        creds.set_password(ldappass)
        urls = samba3.lp.get("passdb backend").split(":", 1)[1].strip('"')
        for url in urls.split():
            try:
                ldb_object = Ldb(url, credentials=creds)
            except ldb.LdbError as e:
                raise ProvisioningError("Could not open ldb connection to %s, the error message is: %s" % (url, e))
            else:
                break
    logger.info("Exporting posix attributes")
    userlist = s3db.search_users(0)
    for entry in userlist:
        username = entry['account_name']
        if username in uids.keys():
            try:
                if ldap:
                    homes[username] = get_posix_attr_from_ldap_backend(logger, ldb_object, base_dn, username, "homeDirectory")
                else:
                    homes[username] = pwd.getpwnam(username).pw_dir
            except KeyError:
                pass
            except IndexError:
                pass

            try:
                if ldap:
                    shells[username] = get_posix_attr_from_ldap_backend(logger, ldb_object, base_dn, username, "loginShell")
                else:
                    shells[username] = pwd.getpwnam(username).pw_shell
            except KeyError:
                pass
            except IndexError:
                pass

            try:
                if ldap:
                    pgids[username] = get_posix_attr_from_ldap_backend(logger, ldb_object, base_dn, username, "gidNumber")
                else:
                    pgids[username] = pwd.getpwnam(username).pw_gid
            except KeyError:
                pass
            except IndexError:
                pass

    logger.info("Reading WINS database")
    samba3_winsdb = None
    try:
        samba3_winsdb = samba3.get_wins_db()
    except IOError as e:
        logger.warn('Cannot open wins database, Ignoring: %s', str(e))

    if not (serverrole == "ROLE_DOMAIN_BDC" or serverrole == "ROLE_DOMAIN_PDC"):
        dns_backend = "NONE"

    # If we found an admin user, set a fake pw that we will override.
    # This avoids us printing out an admin password that we won't actually
    # set.
    if admin_user:
        adminpass = generate_random_password(12, 32)
    else:
        adminpass = None

    # Do full provision
    result = provision(logger, session_info,
                       targetdir=targetdir, realm=realm, domain=domainname,
                       domainsid=domainsid, next_rid=next_rid,
                       dc_rid=machinerid, adminpass=adminpass,
                       dom_for_fun_level=dsdb.DS_DOMAIN_FUNCTION_2003,
                       hostname=netbiosname.lower(), machinepass=machinepass,
                       serverrole=serverrole, samdb_fill=FILL_FULL,
                       useeadb=useeadb, dns_backend=dns_backend, use_rfc2307=True,
                       use_ntvfs=use_ntvfs, skip_sysvolacl=True)
    result.report_logger(logger)

    # Import WINS database
    logger.info("Importing WINS database")

    if samba3_winsdb:
        import_wins(Ldb(result.paths.winsdb), samba3_winsdb)

    # Set Account policy
    logger.info("Importing Account policy")
    import_sam_policy(result.samdb, policy, logger)

    # Migrate IDMAP database
    logger.info("Importing idmap database")
    import_idmap(result.idmap, samba3, logger)

    # Set the s3 context for samba4 configuration
    new_lp_ctx = s3param.get_context()
    new_lp_ctx.load(result.lp.configfile)
    new_lp_ctx.set("private dir", result.lp.get("private dir"))
    new_lp_ctx.set("state directory", result.lp.get("state directory"))
    new_lp_ctx.set("lock directory", result.lp.get("lock directory"))

    # Connect to samba4 backend
    s4_passdb = passdb.PDB(new_lp_ctx.get("passdb backend"))

    # Start a new transaction (should speed this up a little, due to index churn)
    result.samdb.transaction_start()

    logger.info("Adding groups")
    try:
        # Export groups to samba4 backend
        logger.info("Importing groups")
        for g in grouplist:
            # Ignore uninitialized groups (gid = -1)
            if g.gid != -1:
                add_group_from_mapping_entry(result.samdb, g, logger)
                add_ad_posix_idmap_entry(result.samdb, g.sid, g.gid, "ID_TYPE_GID", logger)
                add_posix_attrs(samdb=result.samdb, sid=g.sid, name=g.nt_name, nisdomain=domainname.lower(), xid_type="ID_TYPE_GID", logger=logger)

    except:
        # We need this, so that we do not give even more errors due to not cancelling the transaction
        result.samdb.transaction_cancel()
        raise

    logger.info("Committing 'add groups' transaction to disk")
    result.samdb.transaction_commit()

    logger.info("Adding users")

    # Export users to samba4 backend
    logger.info("Importing users")
    for username in userdata:
        if username.lower() == 'administrator':
            if userdata[username].user_sid != dom_sid(str(domainsid) + "-500"):
                logger.error("User 'Administrator' in your existing directory has SID %s, expected it to be %s" % (userdata[username].user_sid, dom_sid(str(domainsid) + "-500")))
                raise ProvisioningError("User 'Administrator' in your existing directory does not have SID ending in -500")
        if username.lower() == 'root':
            if userdata[username].user_sid == dom_sid(str(domainsid) + "-500"):
                logger.warn('User root has been replaced by Administrator')
            else:
                logger.warn('User root has been kept in the directory, it should be removed in favour of the Administrator user')

        s4_passdb.add_sam_account(userdata[username])
        if username in uids:
            add_ad_posix_idmap_entry(result.samdb, userdata[username].user_sid, uids[username], "ID_TYPE_UID", logger)
            if (username in homes) and (homes[username] is not None) and \
               (username in shells) and (shells[username] is not None) and \
               (username in pgids) and (pgids[username] is not None):
                add_posix_attrs(samdb=result.samdb, sid=userdata[username].user_sid, name=username, nisdomain=domainname.lower(), xid_type="ID_TYPE_UID", home=homes[username], shell=shells[username], pgid=pgids[username], logger=logger)

    logger.info("Adding users to groups")
    # Start a new transaction (should speed this up a little, due to index churn)
    result.samdb.transaction_start()

    try:
        for g in grouplist:
            if str(g.sid) in groupmembers:
                add_users_to_group(result.samdb, g, groupmembers[str(g.sid)], logger)

    except:
        # We need this, so that we do not give even more errors due to not cancelling the transaction
        result.samdb.transaction_cancel()
        raise

    logger.info("Committing 'add users to groups' transaction to disk")
    result.samdb.transaction_commit()

    # Set password for administrator
    if admin_user:
        logger.info("Setting password for administrator")
        admin_userdata = s4_passdb.getsampwnam("administrator")
        admin_userdata.nt_passwd = userdata[admin_user].nt_passwd
        if userdata[admin_user].lanman_passwd:
            admin_userdata.lanman_passwd = userdata[admin_user].lanman_passwd
        admin_userdata.pass_last_set_time = userdata[admin_user].pass_last_set_time
        if userdata[admin_user].pw_history:
            admin_userdata.pw_history = userdata[admin_user].pw_history
        s4_passdb.update_sam_account(admin_userdata)
        logger.info("Administrator password has been set to password of user '%s'", admin_user)

    if result.server_role == "active directory domain controller":
        setsysvolacl(result.samdb, result.paths.netlogon, result.paths.sysvol,
                     result.paths.root_uid, result.paths.root_gid,
                     security.dom_sid(result.domainsid), result.names.dnsdomain,
                     result.names.domaindn, result.lp, use_ntvfs)

    # FIXME: import_registry(registry.Registry(), samba3.get_registry())
    # FIXME: shares
