s3:tests: Also clear the download area in smbget msdfs_link test

[Samba.git] / python / samba / dbchecker.py

# Samba4 AD database checker
#
# Copyright (C) Andrew Tridgell 2011
# Copyright (C) Matthieu Patou <mat@matws.net> 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/>.
#

import ldb
import samba
import time
from base64 import b64decode
from samba import dsdb
from samba import common
from samba.dcerpc import misc
from samba.dcerpc import drsuapi
from samba.ndr import ndr_unpack, ndr_pack
from samba.dcerpc import drsblobs
from samba.samdb import dsdb_Dn
from samba.dcerpc import security
from samba.descriptor import get_wellknown_sds, get_diff_sds
from samba.auth import system_session, admin_session
from samba.netcmd import CommandError
from samba.netcmd.fsmo import get_fsmo_roleowner
from samba.colour import c_RED, c_DARK_YELLOW, c_DARK_CYAN, c_DARK_GREEN

def dump_attr_values(vals):
    """Stringify a value list, using utf-8 if possible (which some tests
    want), or the python bytes representation otherwise (with leading
    'b' and escapes like b'\x00').
    """
    result = []
    for value in vals:
        try:
            result.append(value.decode('utf-8'))
        except UnicodeDecodeError:
            result.append(repr(value))
    return ','.join(result)


class dbcheck(object):
    """check a SAM database for errors"""

    def __init__(self, samdb, samdb_schema=None, verbose=False, fix=False,
                 yes=False, quiet=False, in_transaction=False,
                 quick_membership_checks=False,
                 reset_well_known_acls=False,
                 check_expired_tombstones=False,
                 colour=False):
        self.samdb = samdb
        self.dict_oid_name = None
        self.samdb_schema = (samdb_schema or samdb)
        self.verbose = verbose
        self.fix = fix
        self.yes = yes
        self.quiet = quiet
        self.colour = colour
        self.remove_all_unknown_attributes = False
        self.remove_all_empty_attributes = False
        self.fix_all_normalisation = False
        self.fix_all_duplicates = False
        self.fix_all_DN_GUIDs = False
        self.fix_all_binary_dn = False
        self.remove_implausible_deleted_DN_links = False
        self.remove_plausible_deleted_DN_links = False
        self.fix_all_string_dn_component_mismatch = False
        self.fix_all_GUID_dn_component_mismatch = False
        self.fix_all_SID_dn_component_mismatch = False
        self.fix_all_SID_dn_component_missing = False
        self.fix_all_old_dn_string_component_mismatch = False
        self.fix_all_metadata = False
        self.fix_time_metadata = False
        self.fix_undead_linked_attributes = False
        self.fix_all_missing_backlinks = False
        self.fix_all_orphaned_backlinks = False
        self.fix_all_missing_forward_links = False
        self.duplicate_link_cache = dict()
        self.recover_all_forward_links = False
        self.fix_rmd_flags = False
        self.fix_ntsecuritydescriptor = False
        self.fix_ntsecuritydescriptor_owner_group = False
        self.seize_fsmo_role = False
        self.move_to_lost_and_found = False
        self.fix_instancetype = False
        self.fix_replmetadata_zero_invocationid = False
        self.fix_replmetadata_duplicate_attid = False
        self.fix_replmetadata_wrong_attid = False
        self.fix_replmetadata_unsorted_attid = False
        self.fix_deleted_deleted_objects = False
        self.fix_dn = False
        self.fix_base64_userparameters = False
        self.fix_utf8_userparameters = False
        self.fix_doubled_userparameters = False
        self.fix_sid_rid_set_conflict = False
        self.quick_membership_checks = quick_membership_checks
        self.reset_well_known_acls = reset_well_known_acls
        self.check_expired_tombstones = check_expired_tombstones
        self.expired_tombstones = 0
        self.reset_all_well_known_acls = False
        self.in_transaction = in_transaction
        self.infrastructure_dn = ldb.Dn(samdb, "CN=Infrastructure," + samdb.domain_dn())
        self.naming_dn = ldb.Dn(samdb, "CN=Partitions,%s" % samdb.get_config_basedn())
        self.schema_dn = samdb.get_schema_basedn()
        self.rid_dn = ldb.Dn(samdb, "CN=RID Manager$,CN=System," + samdb.domain_dn())
        self.ntds_dsa = ldb.Dn(samdb, samdb.get_dsServiceName())
        self.class_schemaIDGUID = {}
        self.wellknown_sds = get_wellknown_sds(self.samdb)
        self.fix_all_missing_objectclass = False
        self.fix_missing_deleted_objects = False
        self.fix_replica_locations = False
        self.fix_missing_rid_set_master = False
        self.fix_changes_after_deletion_bug = False

        self.dn_set = set()
        self.link_id_cache = {}
        self.name_map = {}
        try:
            base_dn = "CN=DnsAdmins,%s" % samdb.get_wellknown_dn(
                                                samdb.get_default_basedn(),
                                                dsdb.DS_GUID_USERS_CONTAINER)
            res = samdb.search(base=base_dn, scope=ldb.SCOPE_BASE,
                               attrs=["objectSid"])
            dnsadmins_sid = ndr_unpack(security.dom_sid, res[0]["objectSid"][0])
            self.name_map['DnsAdmins'] = str(dnsadmins_sid)
        except ldb.LdbError as e5:
            (enum, estr) = e5.args
            if enum != ldb.ERR_NO_SUCH_OBJECT:
                raise

        self.system_session_info = system_session()
        self.admin_session_info = admin_session(None, samdb.get_domain_sid())

        res = self.samdb.search(base=self.ntds_dsa, scope=ldb.SCOPE_BASE, attrs=['msDS-hasMasterNCs', 'hasMasterNCs'])
        if "msDS-hasMasterNCs" in res[0]:
            self.write_ncs = res[0]["msDS-hasMasterNCs"]
        else:
            # If the Forest Level is less than 2003 then there is no
            # msDS-hasMasterNCs, so we fall back to hasMasterNCs
            # no need to merge as all the NCs that are in hasMasterNCs must
            # also be in msDS-hasMasterNCs (but not the opposite)
            if "hasMasterNCs" in res[0]:
                self.write_ncs = res[0]["hasMasterNCs"]
            else:
                self.write_ncs = None

        res = self.samdb.search(base="", scope=ldb.SCOPE_BASE, attrs=['namingContexts'])
        self.deleted_objects_containers = []
        self.ncs_lacking_deleted_containers = []
        self.dns_partitions = []
        try:
            self.ncs = res[0]["namingContexts"]
        except KeyError:
            pass
        except IndexError:
            pass

        for nc in self.ncs:
            try:
                dn = self.samdb.get_wellknown_dn(ldb.Dn(self.samdb, nc.decode('utf8')),
                                                 dsdb.DS_GUID_DELETED_OBJECTS_CONTAINER)
                self.deleted_objects_containers.append(dn)
            except KeyError:
                self.ncs_lacking_deleted_containers.append(ldb.Dn(self.samdb, nc.decode('utf8')))

        domaindns_zone = 'DC=DomainDnsZones,%s' % self.samdb.get_default_basedn()
        forestdns_zone = 'DC=ForestDnsZones,%s' % self.samdb.get_root_basedn()
        domain = self.samdb.search(scope=ldb.SCOPE_ONELEVEL,
                                   attrs=["msDS-NC-Replica-Locations", "msDS-NC-RO-Replica-Locations"],
                                   base=self.samdb.get_partitions_dn(),
                                   expression="(&(objectClass=crossRef)(ncName=%s))" % domaindns_zone)
        if len(domain) == 1:
            self.dns_partitions.append((ldb.Dn(self.samdb, forestdns_zone), domain[0]))

        forest = self.samdb.search(scope=ldb.SCOPE_ONELEVEL,
                                   attrs=["msDS-NC-Replica-Locations", "msDS-NC-RO-Replica-Locations"],
                                   base=self.samdb.get_partitions_dn(),
                                   expression="(&(objectClass=crossRef)(ncName=%s))" % forestdns_zone)
        if len(forest) == 1:
            self.dns_partitions.append((ldb.Dn(self.samdb, domaindns_zone), forest[0]))

        fsmo_dn = ldb.Dn(self.samdb, "CN=RID Manager$,CN=System," + self.samdb.domain_dn())
        rid_master = get_fsmo_roleowner(self.samdb, fsmo_dn, "rid")
        if ldb.Dn(self.samdb, self.samdb.get_dsServiceName()) == rid_master:
            self.is_rid_master = True
        else:
            self.is_rid_master = False

        # To get your rid set
        # 1. Get server name
        res = self.samdb.search(base=ldb.Dn(self.samdb, self.samdb.get_serverName()),
                                scope=ldb.SCOPE_BASE, attrs=["serverReference"])
        # 2. Get server reference
        self.server_ref_dn = ldb.Dn(self.samdb, res[0]['serverReference'][0].decode('utf8'))

        # 3. Get RID Set
        res = self.samdb.search(base=self.server_ref_dn,
                                scope=ldb.SCOPE_BASE, attrs=['rIDSetReferences'])
        if "rIDSetReferences" in res[0]:
            self.rid_set_dn = ldb.Dn(self.samdb, res[0]['rIDSetReferences'][0].decode('utf8'))
        else:
            self.rid_set_dn = None

        ntds_service_dn = "CN=Directory Service,CN=Windows NT,CN=Services,%s" % \
                          self.samdb.get_config_basedn().get_linearized()
        res = samdb.search(base=ntds_service_dn,
                           scope=ldb.SCOPE_BASE,
                           expression="(objectClass=nTDSService)",
                           attrs=["tombstoneLifetime"])
        if "tombstoneLifetime" in res[0]:
            self.tombstoneLifetime = int(res[0]["tombstoneLifetime"][0])
        else:
            self.tombstoneLifetime = 180

        self.compatibleFeatures = []
        self.requiredFeatures = []

        try:
            res = self.samdb.search(scope=ldb.SCOPE_BASE,
                                    base="@SAMBA_DSDB",
                                    attrs=["compatibleFeatures",
                                           "requiredFeatures"])
            if "compatibleFeatures" in res[0]:
                self.compatibleFeatures = res[0]["compatibleFeatures"]
            if "requiredFeatures" in res[0]:
                self.requiredFeatures = res[0]["requiredFeatures"]
        except ldb.LdbError as e6:
            (enum, estr) = e6.args
            if enum != ldb.ERR_NO_SUCH_OBJECT:
                raise

    def check_database(self, DN=None, scope=ldb.SCOPE_SUBTREE, controls=None,
                       attrs=None):
        '''perform a database check, returning the number of errors found'''
        res = self.samdb.search(base=DN, scope=scope, attrs=['dn'], controls=controls)
        self.report('Checking %u objects' % len(res))
        error_count = 0
        self.unfixable_errors = 0

        error_count += self.check_deleted_objects_containers()

        self.attribute_or_class_ids = set()

        for object in res:
            self.dn_set.add(str(object.dn))
            error_count += self.check_object(object.dn, requested_attrs=attrs)

        if DN is None:
            error_count += self.check_rootdse()

        if self.expired_tombstones > 0:
            self.report("NOTICE: found %d expired tombstones, "
                        "'samba' will remove them daily, "
                        "'samba-tool domain tombstones expunge' "
                        "would do that immediately." % (
                        self.expired_tombstones))

        self.report('Checked %u objects (%u errors)' %
                    (len(res), error_count + self.unfixable_errors))

        if self.unfixable_errors != 0:
            self.report(f"WARNING: {self.unfixable_errors} "
                        "of these errors cannot be automatically fixed.")

        if error_count != 0 and not self.fix:
            self.report("Please use 'samba-tool dbcheck --fix' to fix "
                        f"{error_count} errors")

        return error_count

    def check_deleted_objects_containers(self):
        """This function only fixes conflicts on the Deleted Objects
        containers, not the attributes"""
        error_count = 0
        for nc in self.ncs_lacking_deleted_containers:
            if nc == self.schema_dn:
                continue
            error_count += 1
            self.report("ERROR: NC %s lacks a reference to a Deleted Objects container" % nc)
            if not self.confirm_all('Fix missing Deleted Objects container for %s?' % (nc), 'fix_missing_deleted_objects'):
                continue

            dn = ldb.Dn(self.samdb, "CN=Deleted Objects")
            dn.add_base(nc)

            conflict_dn = None
            try:
                # If something already exists here, add a conflict
                res = self.samdb.search(base=dn, scope=ldb.SCOPE_BASE, attrs=[],
                                        controls=["show_deleted:1", "extended_dn:1:1",
                                                  "show_recycled:1", "reveal_internals:0"])
                if len(res) != 0:
                    guid = res[0].dn.get_extended_component("GUID")
                    conflict_dn = ldb.Dn(self.samdb,
                                         "CN=Deleted Objects\\0ACNF:%s" % str(misc.GUID(guid)))
                    conflict_dn.add_base(nc)

            except ldb.LdbError as e2:
                (enum, estr) = e2.args
                if enum == ldb.ERR_NO_SUCH_OBJECT:
                    pass
                else:
                    self.report("Couldn't check for conflicting Deleted Objects container: %s" % estr)
                    return 1

            if conflict_dn is not None:
                try:
                    self.samdb.rename(dn, conflict_dn, ["show_deleted:1", "relax:0", "show_recycled:1"])
                except ldb.LdbError as e1:
                    (enum, estr) = e1.args
                    self.report("Couldn't move old Deleted Objects placeholder: %s to %s: %s" % (dn, conflict_dn, estr))
                    return 1

            # Refresh wellKnownObjects links
            res = self.samdb.search(base=nc, scope=ldb.SCOPE_BASE,
                                    attrs=['wellKnownObjects'],
                                    controls=["show_deleted:1", "extended_dn:0",
                                              "show_recycled:1", "reveal_internals:0"])
            if len(res) != 1:
                self.report("wellKnownObjects was not found for NC %s" % nc)
                return 1

            # Prevent duplicate deleted objects containers just in case
            wko = res[0]["wellKnownObjects"]
            listwko = []
            proposed_objectguid = None
            for o in wko:
                dsdb_dn = dsdb_Dn(self.samdb, o.decode('utf8'), dsdb.DSDB_SYNTAX_BINARY_DN)
                if self.is_deleted_objects_dn(dsdb_dn):
                    self.report("wellKnownObjects had duplicate Deleted Objects value %s" % o)
                    # We really want to put this back in the same spot
                    # as the original one, so that on replication we
                    # merge, rather than conflict.
                    proposed_objectguid = dsdb_dn.dn.get_extended_component("GUID")
                listwko.append(str(o))

            if proposed_objectguid is not None:
                guid_suffix = "\nobjectGUID: %s" % str(misc.GUID(proposed_objectguid))
            else:
                wko_prefix = "B:32:%s" % dsdb.DS_GUID_DELETED_OBJECTS_CONTAINER
                listwko.append('%s:%s' % (wko_prefix, dn))
                guid_suffix = ""

            # Insert a brand new Deleted Objects container
            self.samdb.add_ldif("""dn: %s
objectClass: top
objectClass: container
description: Container for deleted objects
isDeleted: TRUE
isCriticalSystemObject: TRUE
showInAdvancedViewOnly: TRUE
systemFlags: -1946157056%s""" % (dn, guid_suffix),
                                controls=["relax:0", "provision:0"])

            delta = ldb.Message()
            delta.dn = ldb.Dn(self.samdb, str(res[0]["dn"]))
            delta["wellKnownObjects"] = ldb.MessageElement(listwko,
                                                           ldb.FLAG_MOD_REPLACE,
                                                           "wellKnownObjects")

            # Insert the link to the brand new container
            if self.do_modify(delta, ["relax:0"],
                              "NC %s lacks Deleted Objects WKGUID" % nc,
                              validate=False):
                self.report("Added %s well known guid link" % dn)

            self.deleted_objects_containers.append(dn)

        return error_count

    def report(self, msg):
        '''print a message unless quiet is set'''
        if self.quiet:
            return
        if self.colour:
            if msg.startswith('ERROR'):
                msg = c_RED('ERROR') + msg[5:]
            elif msg.startswith('WARNING'):
                msg = c_DARK_YELLOW('WARNING') + msg[7:]
            elif msg.startswith('INFO'):
                msg = c_DARK_CYAN('INFO') + msg[4:]
            elif msg.startswith('NOTICE'):
                msg = c_DARK_CYAN('NOTICE') + msg[6:]
            elif msg.startswith('NOTE'):
                msg = c_DARK_CYAN('NOTE') + msg[4:]
            elif msg.startswith('SKIPPING'):
                msg = c_DARK_GREEN('SKIPPING') + msg[8:]

        print(msg)

    def confirm(self, msg, allow_all=False, forced=False):
        '''confirm a change'''
        if not self.fix:
            return False
        if self.quiet:
            return self.yes
        if self.yes:
            forced = True
        return common.confirm(msg, forced=forced, allow_all=allow_all)

    ################################################################
    # a local confirm function with support for 'all'
    def confirm_all(self, msg, all_attr):
        '''confirm a change with support for "all" '''
        if not self.fix:
            return False
        if getattr(self, all_attr) == 'NONE':
            return False
        if getattr(self, all_attr) == 'ALL':
            forced = True
        else:
            forced = self.yes
        if self.quiet:
            return forced
        c = common.confirm(msg, forced=forced, allow_all=True)
        if c == 'ALL':
            setattr(self, all_attr, 'ALL')
            return True
        if c == 'NONE':
            setattr(self, all_attr, 'NONE')
            return False
        return c

    def do_delete(self, dn, controls, msg):
        '''delete dn with optional verbose output'''
        if self.verbose:
            self.report("delete DN %s" % dn)
        try:
            controls = controls + ["local_oid:%s:0" % dsdb.DSDB_CONTROL_DBCHECK]
            self.samdb.delete(dn, controls=controls)
        except Exception as err:
            if self.in_transaction:
                raise CommandError("%s : %s" % (msg, err))
            self.report("%s : %s" % (msg, err))
            return False
        return True

    def do_modify(self, m, controls, msg, validate=True):
        '''perform a modify with optional verbose output'''
        controls = controls + ["local_oid:%s:0" % dsdb.DSDB_CONTROL_DBCHECK]
        if self.verbose:
            self.report(self.samdb.write_ldif(m, ldb.CHANGETYPE_MODIFY))
            self.report("controls: %r" % controls)
        try:
            self.samdb.modify(m, controls=controls, validate=validate)
        except Exception as err:
            if self.in_transaction:
                raise CommandError("%s : %s" % (msg, err))
            self.report("%s : %s" % (msg, err))
            return False
        return True

    def do_rename(self, from_dn, to_rdn, to_base, controls, msg):
        '''perform a rename with optional verbose output'''
        if self.verbose:
            self.report("""dn: %s
changeType: modrdn
newrdn: %s
deleteOldRdn: 1
newSuperior: %s""" % (str(from_dn), str(to_rdn), str(to_base)))
        try:
            to_dn = to_rdn + to_base
            controls = controls + ["local_oid:%s:0" % dsdb.DSDB_CONTROL_DBCHECK]
            self.samdb.rename(from_dn, to_dn, controls=controls)
        except Exception as err:
            if self.in_transaction:
                raise CommandError("%s : %s" % (msg, err))
            self.report("%s : %s" % (msg, err))
            return False
        return True

    def get_attr_linkID_and_reverse_name(self, attrname):
        if attrname in self.link_id_cache:
            return self.link_id_cache[attrname]
        linkID = self.samdb_schema.get_linkId_from_lDAPDisplayName(attrname)
        if linkID:
            revname = self.samdb_schema.get_backlink_from_lDAPDisplayName(attrname)
        else:
            revname = None
        self.link_id_cache[attrname] = (linkID, revname)
        return linkID, revname

    def err_empty_attribute(self, dn, attrname):
        '''fix empty attributes'''
        self.report("ERROR: Empty attribute %s in %s" % (attrname, dn))
        if not self.confirm_all('Remove empty attribute %s from %s?' % (attrname, dn), 'remove_all_empty_attributes'):
            self.report("Not fixing empty attribute %s" % attrname)
            return

        m = ldb.Message()
        m.dn = dn
        m[attrname] = ldb.MessageElement('', ldb.FLAG_MOD_DELETE, attrname)
        if self.do_modify(m, ["relax:0", "show_recycled:1"],
                          "Failed to remove empty attribute %s" % attrname, validate=False):
            self.report("Removed empty attribute %s" % attrname)

    def err_normalise_mismatch(self, dn, attrname, values):
        '''fix attribute normalisation errors, without altering sort order'''
        self.report("ERROR: Normalisation error for attribute %s in %s" % (attrname, dn))
        mod_list = []
        for val in values:
            normalised = self.samdb.dsdb_normalise_attributes(
                self.samdb_schema, attrname, [val])
            if len(normalised) != 1:
                self.report("Unable to normalise value '%s'" % val)
                mod_list.append((val, ''))
            elif (normalised[0] != val):
                self.report("value '%s' should be '%s'" % (val, normalised[0]))
                mod_list.append((val, normalised[0]))
        if not self.confirm_all('Fix normalisation for %s from %s?' % (attrname, dn), 'fix_all_normalisation'):
            self.report("Not fixing attribute %s" % attrname)
            return

        m = ldb.Message()
        m.dn = dn
        for i in range(0, len(mod_list)):
            (val, nval) = mod_list[i]
            m['value_%u' % i] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)
            if nval != '':
                m['normv_%u' % i] = ldb.MessageElement(nval, ldb.FLAG_MOD_ADD,
                                                       attrname)

        if self.do_modify(m, ["relax:0", "show_recycled:1"],
                          "Failed to normalise attribute %s" % attrname,
                          validate=False):
            self.report("Normalised attribute %s" % attrname)

    def err_normalise_mismatch_replace(self, dn, attrname, values):
        '''fix attribute normalisation and/or sort errors'''
        normalised = self.samdb.dsdb_normalise_attributes(self.samdb_schema, attrname, values)
        if list(normalised) == values:
            # how we got here is a mystery.
            return
        self.report("ERROR: Normalisation error for attribute '%s' in '%s'" % (attrname, dn))
        self.report("Values/Order of values do/does not match: %s/%s!" % (values, list(normalised)))
        if not self.confirm_all("Fix normalisation for '%s' from '%s'?" % (attrname, dn), 'fix_all_normalisation'):
            self.report("Not fixing attribute '%s'" % attrname)
            return

        m = ldb.Message()
        m.dn = dn
        m[attrname] = ldb.MessageElement(normalised, ldb.FLAG_MOD_REPLACE, attrname)

        if self.do_modify(m, ["relax:0", "show_recycled:1"],
                          "Failed to normalise attribute %s" % attrname,
                          validate=False):
            self.report("Normalised attribute %s" % attrname)

    def err_duplicate_values(self, dn, attrname, dup_values, values):
        '''fix duplicate attribute values'''
        self.report("ERROR: Duplicate values for attribute '%s' in '%s'" % (attrname, dn))
        self.report("Values contain a duplicate: [%s]/[%s]!" %
                    (dump_attr_values(dup_values), dump_attr_values(values)))
        if not self.confirm_all("Fix duplicates for '%s' from '%s'?" % (attrname, dn), 'fix_all_duplicates'):
            self.report("Not fixing attribute '%s'" % attrname)
            return

        m = ldb.Message()
        m.dn = dn
        m[attrname] = ldb.MessageElement(values, ldb.FLAG_MOD_REPLACE, attrname)

        if self.do_modify(m, ["relax:0", "show_recycled:1"],
                          "Failed to remove duplicate value on attribute %s" % attrname,
                          validate=False):
            self.report("Removed duplicate value on attribute %s" % attrname)

    def is_deleted_objects_dn(self, dsdb_dn):
        '''see if a dsdb_Dn is the special Deleted Objects DN'''
        return dsdb_dn.prefix == "B:32:%s:" % dsdb.DS_GUID_DELETED_OBJECTS_CONTAINER

    def err_missing_objectclass(self, dn):
        """handle object without objectclass"""
        self.report("ERROR: missing objectclass in object %s.  If you have another working DC, please run 'samba-tool drs replicate --full-sync --local <destinationDC> <sourceDC> %s'" % (dn, self.samdb.get_nc_root(dn)))
        if not self.confirm_all("If you cannot re-sync from another DC, do you wish to delete object '%s'?" % dn, 'fix_all_missing_objectclass'):
            self.report("Not deleting object with missing objectclass '%s'" % dn)
            return
        if self.do_delete(dn, ["relax:0"],
                          "Failed to remove DN %s" % dn):
            self.report("Removed DN %s" % dn)

    def err_deleted_dn(self, dn, attrname, val, dsdb_dn, correct_dn, remove_plausible=False):
        """handle a DN pointing to a deleted object"""
        if not remove_plausible:
            self.report("ERROR: target DN is deleted for %s in object %s - %s" % (attrname, dn, val))
            self.report("Target GUID points at deleted DN %r" % str(correct_dn))
            if not self.confirm_all('Remove DN link?', 'remove_implausible_deleted_DN_links'):
                self.report("Not removing")
                return
        else:
            self.report("WARNING: target DN is deleted for %s in object %s - %s" % (attrname, dn, val))
            self.report("Target GUID points at deleted DN %r" % str(correct_dn))
            if not self.confirm_all('Remove stale DN link?', 'remove_plausible_deleted_DN_links'):
                self.report("Not removing")
                return

        m = ldb.Message()
        m.dn = dn
        m['old_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)
        if self.do_modify(m, ["show_recycled:1",
                              "local_oid:%s:0" % dsdb.DSDB_CONTROL_REPLMD_VANISH_LINKS],
                          "Failed to remove deleted DN attribute %s" % attrname):
            self.report("Removed deleted DN on attribute %s" % attrname)

    def err_missing_target_dn_or_GUID(self, dn, attrname, val, dsdb_dn):
        """handle a missing target DN (if specified, GUID form can't be found,
        and otherwise DN string form can't be found)"""

        # Don't change anything if the object itself is deleted
        if str(dn).find('\\0ADEL') != -1:
            # We don't bump the error count as Samba produces these
            # in normal operation
            self.report("WARNING: no target object found for GUID "
                        "component link %s in deleted object "
                        "%s - %s" % (attrname, dn, val))
            self.report("Not removing dangling one-way "
                        "link on deleted object "
                        "(tombstone garbage collection in progress?)")
            return 0

        # check if its a backlink
        linkID, _ = self.get_attr_linkID_and_reverse_name(attrname)
        if (linkID & 1 == 0) and str(dsdb_dn).find('\\0ADEL') == -1:

            linkID, reverse_link_name \
                = self.get_attr_linkID_and_reverse_name(attrname)
            if reverse_link_name is not None:
                self.report("WARNING: no target object found for GUID "
                            "component for one-way forward link "
                            "%s in object "
                            "%s - %s" % (attrname, dn, val))
                self.report("Not removing dangling forward link")
                return 0

            nc_root = self.samdb.get_nc_root(dn)
            try:
                target_nc_root = self.samdb.get_nc_root(dsdb_dn.dn)
            except ldb.LdbError as e:
                (enum, estr) = e.args
                if enum != ldb.ERR_NO_SUCH_OBJECT:
                    raise
                target_nc_root = None

            if target_nc_root is None:
                # We don't bump the error count as Samba produces
                # these in normal operation creating a lab domain (due
                # to the way the rename is handled, links to
                # now-expunged objects will never be fixed to stay
                # inside the NC
                self.report("WARNING: no target object found for GUID "
                            "component for link "
                            "%s in object to %s outside our NCs"
                            "%s - %s" % (attrname, dsdb_dn.dn, dn, val))
                self.report("Not removing dangling one-way "
                            "left-over link outside our NCs "
                            "(we might be building a renamed/lab domain)")
                return 0

            if nc_root != target_nc_root:
                # We don't bump the error count as Samba produces these
                # in normal operation
                self.report("WARNING: no target object found for GUID "
                            "component for cross-partition link "
                            "%s in object "
                            "%s - %s" % (attrname, dn, val))
                self.report("Not removing dangling one-way "
                            "cross-partition link "
                            "(we might be mid-replication)")
                return 0

            # Due to our link handling one-way links pointing to
            # missing objects are plausible.
            #
            # We don't bump the error count as Samba produces these
            # in normal operation
            self.report("WARNING: no target object found for GUID "
                        "component for DN value %s in object "
                        "%s - %s" % (attrname, dn, val))
            self.err_deleted_dn(dn, attrname, val,
                                dsdb_dn, dsdb_dn, True)
            return 0

        # We bump the error count here, as we should have deleted this
        self.report("ERROR: no target object found for GUID "
                    "component for link %s in object "
                    "%s - %s" % (attrname, dn, val))
        self.err_deleted_dn(dn, attrname, val, dsdb_dn, dsdb_dn, False)
        return 1

    def err_missing_dn_GUID_component(self, dn, attrname, val, dsdb_dn, errstr):
        """handle a missing GUID extended DN component"""
        self.report("ERROR: %s component for %s in object %s - %s" % (errstr, attrname, dn, val))
        controls = ["extended_dn:1:1", "show_recycled:1"]
        try:
            res = self.samdb.search(base=str(dsdb_dn.dn), scope=ldb.SCOPE_BASE,
                                    attrs=[], controls=controls)
        except ldb.LdbError as e7:
            (enum, estr) = e7.args
            self.report("unable to find object for DN %s - (%s)" % (dsdb_dn.dn, estr))
            if enum != ldb.ERR_NO_SUCH_OBJECT:
                raise
            self.err_missing_target_dn_or_GUID(dn, attrname, val, dsdb_dn)
            return
        if len(res) == 0:
            self.report("unable to find object for DN %s" % dsdb_dn.dn)
            self.err_missing_target_dn_or_GUID(dn, attrname, val, dsdb_dn)
            return
        dsdb_dn.dn = res[0].dn

        if not self.confirm_all('Change DN to %s?' % str(dsdb_dn), 'fix_all_DN_GUIDs'):
            self.report("Not fixing %s" % errstr)
            return
        m = ldb.Message()
        m.dn = dn
        m['old_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)
        m['new_value'] = ldb.MessageElement(str(dsdb_dn), ldb.FLAG_MOD_ADD, attrname)

        if self.do_modify(m, ["show_recycled:1"],
                          "Failed to fix %s on attribute %s" % (errstr, attrname)):
            self.report("Fixed %s on attribute %s" % (errstr, attrname))

    def err_incorrect_binary_dn(self, dn, attrname, val, dsdb_dn, errstr):
        """handle an incorrect binary DN component"""
        self.report("ERROR: %s binary component for %s in object %s - %s" % (errstr, attrname, dn, val))

        if not self.confirm_all('Change DN to %s?' % str(dsdb_dn), 'fix_all_binary_dn'):
            self.report("Not fixing %s" % errstr)
            return
        m = ldb.Message()
        m.dn = dn
        m['old_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)
        m['new_value'] = ldb.MessageElement(str(dsdb_dn), ldb.FLAG_MOD_ADD, attrname)

        if self.do_modify(m, ["show_recycled:1"],
                          "Failed to fix %s on attribute %s" % (errstr, attrname)):
            self.report("Fixed %s on attribute %s" % (errstr, attrname))

    def err_dn_string_component_old(self, dn, attrname, val, dsdb_dn, correct_dn):
        """handle a DN string being incorrect due to a rename or delete"""
        self.report("NOTE: old (due to rename or delete) DN string component for %s in object %s - %s" % (attrname, dn, val))
        dsdb_dn.dn = correct_dn

        if not self.confirm_all('Change DN to %s?' % str(dsdb_dn),
                                'fix_all_old_dn_string_component_mismatch'):
            self.report("Not fixing old string component")
            return
        m = ldb.Message()
        m.dn = dn
        m['old_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)
        m['new_value'] = ldb.MessageElement(str(dsdb_dn), ldb.FLAG_MOD_ADD, attrname)
        if self.do_modify(m, ["show_recycled:1",
                              "local_oid:%s:1" % dsdb.DSDB_CONTROL_DBCHECK_FIX_LINK_DN_NAME],
                          "Failed to fix old DN string on attribute %s" % (attrname)):
            self.report("Fixed old DN string on attribute %s" % (attrname))

    def err_dn_component_target_mismatch(self, dn, attrname, val, dsdb_dn, correct_dn, mismatch_type):
        """handle a DN string being incorrect"""
        self.report("ERROR: incorrect DN %s component for %s in object %s - %s" % (mismatch_type, attrname, dn, val))
        dsdb_dn.dn = correct_dn

        if not self.confirm_all('Change DN to %s?' % str(dsdb_dn),
                                'fix_all_%s_dn_component_mismatch' % mismatch_type):
            self.report("Not fixing %s component mismatch" % mismatch_type)
            return
        m = ldb.Message()
        m.dn = dn
        m['old_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)
        m['new_value'] = ldb.MessageElement(str(dsdb_dn), ldb.FLAG_MOD_ADD, attrname)
        if self.do_modify(m, ["show_recycled:1"],
                          "Failed to fix incorrect DN %s on attribute %s" % (mismatch_type, attrname)):
            self.report("Fixed incorrect DN %s on attribute %s" % (mismatch_type, attrname))

    def err_dn_component_missing_target_sid(self, dn, attrname, val, dsdb_dn, target_sid_blob):
        """fix missing <SID=...> on linked attributes"""
        self.report("ERROR: missing DN SID component for %s in object %s - %s" % (attrname, dn, val))

        if len(dsdb_dn.prefix) != 0:
            self.report("Not fixing missing DN SID on DN+BINARY or DN+STRING")
            return

        correct_dn = ldb.Dn(self.samdb, dsdb_dn.dn.extended_str())
        correct_dn.set_extended_component("SID", target_sid_blob)

        if not self.confirm_all('Change DN to %s?' % correct_dn.extended_str(),
                                'fix_all_SID_dn_component_missing'):
            self.report("Not fixing missing DN SID component")
            return

        target_guid_blob = correct_dn.get_extended_component("GUID")
        guid_sid_dn = ldb.Dn(self.samdb, "")
        guid_sid_dn.set_extended_component("GUID", target_guid_blob)
        guid_sid_dn.set_extended_component("SID", target_sid_blob)

        m = ldb.Message()
        m.dn = dn
        m['new_value'] = ldb.MessageElement(guid_sid_dn.extended_str(), ldb.FLAG_MOD_ADD, attrname)
        controls = [
            "show_recycled:1",
            "local_oid:%s:1" % dsdb.DSDB_CONTROL_DBCHECK_FIX_LINK_DN_SID
        ]
        if self.do_modify(m, controls,
                          "Failed to ADD missing DN SID on attribute %s" % (attrname)):
            self.report("Fixed missing DN SID on attribute %s" % (attrname))

    def err_unknown_attribute(self, obj, attrname):
        '''handle an unknown attribute error'''
        self.report("ERROR: unknown attribute '%s' in %s" % (attrname, obj.dn))
        if not self.confirm_all('Remove unknown attribute %s' % attrname, 'remove_all_unknown_attributes'):
            self.report("Not removing %s" % attrname)
            return
        m = ldb.Message()
        m.dn = obj.dn
        m['old_value'] = ldb.MessageElement([], ldb.FLAG_MOD_DELETE, attrname)
        if self.do_modify(m, ["relax:0", "show_recycled:1"],
                          "Failed to remove unknown attribute %s" % attrname):
            self.report("Removed unknown attribute %s" % (attrname))

    def err_undead_linked_attribute(self, obj, attrname, val):
        '''handle a link that should not be there on a deleted object'''
        self.report("ERROR: linked attribute '%s' to '%s' is present on "
                    "deleted object %s" % (attrname, val, obj.dn))
        if not self.confirm_all('Remove linked attribute %s' % attrname, 'fix_undead_linked_attributes'):
            self.report("Not removing linked attribute %s" % attrname)
            return
        m = ldb.Message()
        m.dn = obj.dn
        m['old_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_DELETE, attrname)

        if self.do_modify(m, ["show_recycled:1", "show_deleted:1", "reveal_internals:0",
                              "local_oid:%s:0" % dsdb.DSDB_CONTROL_REPLMD_VANISH_LINKS],
                          "Failed to delete forward link %s" % attrname):
            self.report("Fixed undead forward link %s" % (attrname))

    def err_missing_backlink(self, obj, attrname, val, backlink_name, target_dn):
        '''handle a missing backlink value'''
        self.report("ERROR: missing backlink attribute '%s' in %s for link %s in %s" % (backlink_name, target_dn, attrname, obj.dn))
        if not self.confirm_all('Fix missing backlink %s' % backlink_name, 'fix_all_missing_backlinks'):
            self.report("Not fixing missing backlink %s" % backlink_name)
            return
        m = ldb.Message()
        m.dn = target_dn
        m['new_value'] = ldb.MessageElement(val, ldb.FLAG_MOD_ADD, backlink_name)
        if self.do_modify(m, ["show_recycled:1", "relax:0"],
                          "Failed to fix missing backlink %s" % backlink_name):
            self.report("Fixed missing backlink %s" % (backlink_name))

    def err_incorrect_rmd_flags(self, obj, attrname, revealed_dn):
        '''handle a incorrect RMD_FLAGS value'''
        rmd_flags = int(revealed_dn.dn.get_extended_component("RMD_FLAGS"))
        self.report("ERROR: incorrect RMD_FLAGS value %u for attribute '%s' in %s for link %s" % (rmd_flags, attrname, obj.dn, revealed_dn.dn.extended_str()))
        if not self.confirm_all('Fix incorrect RMD_FLAGS %u' % rmd_flags, 'fix_rmd_flags'):
            self.report("Not fixing incorrect RMD_FLAGS %u" % rmd_flags)
            return
        m = ldb.Message()
        m.dn = obj.dn
        m['old_value'] = ldb.MessageElement(str(revealed_dn), ldb.FLAG_MOD_DELETE, attrname)
        if self.do_modify(m, ["show_recycled:1", "reveal_internals:0", "show_deleted:0"],
                          "Failed to fix incorrect RMD_FLAGS %u" % rmd_flags):
            self.report("Fixed incorrect RMD_FLAGS %u" % (rmd_flags))

    def err_orphaned_backlink(self, obj_dn, backlink_attr, backlink_val,
                              target_dn, forward_attr, forward_syntax,
                              check_duplicates=True):
        '''handle a orphaned backlink value'''
        if check_duplicates is True and self.has_duplicate_links(target_dn, forward_attr, forward_syntax):
            self.report("WARNING: Keep orphaned backlink attribute " +
                        "'%s' in '%s' for link '%s' in '%s'" % (
                            backlink_attr, obj_dn, forward_attr, target_dn))
            return
        self.report("ERROR: orphaned backlink attribute '%s' in %s for link %s in %s" % (backlink_attr, obj_dn, forward_attr, target_dn))
        if not self.confirm_all('Remove orphaned backlink %s' % backlink_attr, 'fix_all_orphaned_backlinks'):
            self.report("Not removing orphaned backlink %s" % backlink_attr)
            return
        m = ldb.Message()
        m.dn = obj_dn
        m['value'] = ldb.MessageElement(backlink_val, ldb.FLAG_MOD_DELETE, backlink_attr)
        if self.do_modify(m, ["show_recycled:1", "relax:0"],
                          "Failed to fix orphaned backlink %s" % backlink_attr):
            self.report("Fixed orphaned backlink %s" % (backlink_attr))

    def err_recover_forward_links(self, obj, forward_attr, forward_vals):
        '''handle a duplicate links value'''

        self.report("RECHECK: 'Missing/Duplicate/Correct link' lines above for attribute '%s' in '%s'" % (forward_attr, obj.dn))

        if not self.confirm_all("Commit fixes for (missing/duplicate) forward links in attribute '%s'" % forward_attr, 'recover_all_forward_links'):
            self.report("Not fixing corrupted (missing/duplicate) forward links in attribute '%s' of '%s'" % (
                        forward_attr, obj.dn))
            return
        m = ldb.Message()
        m.dn = obj.dn
        m['value'] = ldb.MessageElement(forward_vals, ldb.FLAG_MOD_REPLACE, forward_attr)
        if self.do_modify(m, ["local_oid:%s:1" % dsdb.DSDB_CONTROL_DBCHECK_FIX_DUPLICATE_LINKS],
                          "Failed to fix duplicate links in attribute '%s'" % forward_attr):
            self.report("Fixed duplicate links in attribute '%s'" % (forward_attr))
            duplicate_cache_key = "%s:%s" % (str(obj.dn), forward_attr)
            assert duplicate_cache_key in self.duplicate_link_cache
            self.duplicate_link_cache[duplicate_cache_key] = False

    def err_no_fsmoRoleOwner(self, obj):
        '''handle a missing fSMORoleOwner'''
        self.report("ERROR: fSMORoleOwner not found for role %s" % (obj.dn))
        res = self.samdb.search("",
                                scope=ldb.SCOPE_BASE, attrs=["dsServiceName"])
        assert len(res) == 1
        serviceName = str(res[0]["dsServiceName"][0])
        if not self.confirm_all('Seize role %s onto current DC by adding fSMORoleOwner=%s' % (obj.dn, serviceName), 'seize_fsmo_role'):
            self.report("Not Seizing role %s onto current DC by adding fSMORoleOwner=%s" % (obj.dn, serviceName))
            return
        m = ldb.Message()
        m.dn = obj.dn
        m['value'] = ldb.MessageElement(serviceName, ldb.FLAG_MOD_ADD, 'fSMORoleOwner')
        if self.do_modify(m, [],
                          "Failed to seize role %s onto current DC by adding fSMORoleOwner=%s" % (obj.dn, serviceName)):
            self.report("Seized role %s onto current DC by adding fSMORoleOwner=%s" % (obj.dn, serviceName))

    def err_missing_parent(self, obj):
        '''handle a missing parent'''
        self.report("ERROR: parent object not found for %s" % (obj.dn))
        if not self.confirm_all('Move object %s into LostAndFound?' % (obj.dn), 'move_to_lost_and_found'):
            self.report('Not moving object %s into LostAndFound' % (obj.dn))
            return

        keep_transaction = False
        self.samdb.transaction_start()
        try:
            nc_root = self.samdb.get_nc_root(obj.dn)
            lost_and_found = self.samdb.get_wellknown_dn(nc_root, dsdb.DS_GUID_LOSTANDFOUND_CONTAINER)
            new_dn = ldb.Dn(self.samdb, str(obj.dn))
            new_dn.remove_base_components(len(new_dn) - 1)
            if self.do_rename(obj.dn, new_dn, lost_and_found, ["show_deleted:0", "relax:0"],
                              "Failed to rename object %s into lostAndFound at %s" % (obj.dn, new_dn + lost_and_found)):
                self.report("Renamed object %s into lostAndFound at %s" % (obj.dn, new_dn + lost_and_found))

                m = ldb.Message()
                m.dn = obj.dn
                m['lastKnownParent'] = ldb.MessageElement(str(obj.dn.parent()), ldb.FLAG_MOD_REPLACE, 'lastKnownParent')

                if self.do_modify(m, [],
                                  "Failed to set lastKnownParent on lostAndFound object at %s" % (new_dn + lost_and_found)):
                    self.report("Set lastKnownParent on lostAndFound object at %s" % (new_dn + lost_and_found))
                    keep_transaction = True
        except:
            self.samdb.transaction_cancel()
            raise

        if keep_transaction:
            self.samdb.transaction_commit()
        else:
            self.samdb.transaction_cancel()

    def err_wrong_dn(self, obj, new_dn, rdn_attr, rdn_val, name_val, controls):
        '''handle a wrong dn'''

        new_rdn = ldb.Dn(self.samdb, str(new_dn))
        new_rdn.remove_base_components(len(new_rdn) - 1)
        new_parent = new_dn.parent()

        attributes = ""
        if rdn_val != name_val:
            attributes += "%s=%r " % (rdn_attr, rdn_val)
        attributes += "name=%r" % (name_val)

        self.report("ERROR: wrong dn[%s] %s new_dn[%s]" % (obj.dn, attributes, new_dn))
        if not self.confirm_all("Rename %s to %s?" % (obj.dn, new_dn), 'fix_dn'):
            self.report("Not renaming %s to %s" % (obj.dn, new_dn))
            return

        if self.do_rename(obj.dn, new_rdn, new_parent, controls,
                          "Failed to rename object %s into %s" % (obj.dn, new_dn)):
            self.report("Renamed %s into %s" % (obj.dn, new_dn))

    def err_wrong_instancetype(self, obj, calculated_instancetype):
        '''handle a wrong instanceType'''
        self.report("ERROR: wrong instanceType %s on %s, should be %d" % (obj["instanceType"], obj.dn, calculated_instancetype))
        if not self.confirm_all('Change instanceType from %s to %d on %s?' % (obj["instanceType"], calculated_instancetype, obj.dn), 'fix_instancetype'):
            self.report('Not changing instanceType from %s to %d on %s' % (obj["instanceType"], calculated_instancetype, obj.dn))
            return

        m = ldb.Message()
        m.dn = obj.dn
        m['value'] = ldb.MessageElement(str(calculated_instancetype), ldb.FLAG_MOD_REPLACE, 'instanceType')
        if self.do_modify(m, ["local_oid:%s:0" % dsdb.DSDB_CONTROL_DBCHECK_MODIFY_RO_REPLICA],
                          "Failed to correct missing instanceType on %s by setting instanceType=%d" % (obj.dn, calculated_instancetype)):
            self.report("Corrected instancetype on %s by setting instanceType=%d" % (obj.dn, calculated_instancetype))

    def err_short_userParameters(self, obj, attrname, value):
        # This is a truncated userParameters due to a pre 4.1 replication bug
        self.report("ERROR: incorrect userParameters value on object %s.  If you have another working DC that does not give this warning, please run 'samba-tool drs replicate --full-sync --local <destinationDC> <sourceDC> %s'" % (obj.dn, self.samdb.get_nc_root(obj.dn)))

    def err_base64_userParameters(self, obj, attrname, value):
        '''handle a userParameters that is wrongly base64 encoded'''
        self.report("ERROR: wrongly formatted userParameters %s on %s, should not be base64-encoded" % (value, obj.dn))
        if not self.confirm_all('Convert userParameters from base64 encoding on %s?' % (obj.dn), 'fix_base64_userparameters'):
            self.report('Not changing userParameters from base64 encoding on %s' % (obj.dn))
            return

        m = ldb.Message()
        m.dn = obj.dn
        m['value'] = ldb.MessageElement(b64decode(obj[attrname][0]), ldb.FLAG_MOD_REPLACE, 'userParameters')
        if self.do_modify(m, [],
                          "Failed to correct base64-encoded userParameters on %s by converting from base64" % (obj.dn)):
            self.report("Corrected base64-encoded userParameters on %s by converting from base64" % (obj.dn))

    def err_utf8_userParameters(self, obj, attrname, value):
        '''handle a userParameters that is wrongly utf-8 encoded'''
        self.report("ERROR: wrongly formatted userParameters on %s, "
                    "should not be pseudo-UTF8 encoded" % (obj.dn))
        if not self.confirm_all('Convert userParameters from UTF8 encoding on %s?' % (obj.dn), 'fix_utf8_userparameters'):
            self.report('Not changing userParameters from UTF8 encoding on %s' % (obj.dn))
            return

        m = ldb.Message()
        m.dn = obj.dn
        m['value'] = ldb.MessageElement(obj[attrname][0].decode('utf8').encode('utf-16-le'),
                                        ldb.FLAG_MOD_REPLACE, 'userParameters')
        if self.do_modify(m, [],
                          "Failed to correct psudo-UTF8 encoded userParameters on %s by converting from UTF8" % (obj.dn)):
            self.report("Corrected psudo-UTF8 encoded userParameters on %s by converting from UTF8" % (obj.dn))

    def err_doubled_userParameters(self, obj, attrname, value):
        '''handle a userParameters that has been utf-16 encoded twice'''
        self.report("ERROR: wrongly formatted userParameters on %s, should not be double UTF16 encoded" % (obj.dn))
        if not self.confirm_all('Convert userParameters from doubled UTF-16 encoding on %s?' % (obj.dn), 'fix_doubled_userparameters'):
            self.report('Not changing userParameters from doubled UTF-16 encoding on %s' % (obj.dn))
            return

        m = ldb.Message()
        m.dn = obj.dn
        # m['value'] = ldb.MessageElement(obj[attrname][0].decode('utf-16-le').decode('utf-16-le').encode('utf-16-le'),
        # hmm the above old python2 code doesn't make sense to me and cannot
        # work in python3 because a string doesn't have a decode method.
        # However in python2 for some unknown reason this double decode
        # followed by encode seems to result in what looks like utf8.
        # In python2 just .decode('utf-16-le').encode('utf-16-le') does nothing
        # but trigger the 'double UTF16 encoded' condition again :/
        #
        # In python2 and python3 value.decode('utf-16-le').encode('utf8') seems
        # to do the trick and work as expected.
        m['value'] = ldb.MessageElement(obj[attrname][0].decode('utf-16-le').encode('utf8'),
                                        ldb.FLAG_MOD_REPLACE, 'userParameters')

        if self.do_modify(m, [],
                          "Failed to correct doubled-UTF16 encoded userParameters on %s by converting" % (obj.dn)):
            self.report("Corrected doubled-UTF16 encoded userParameters on %s by converting" % (obj.dn))

    def err_odd_userParameters(self, obj, attrname):
        """Fix a truncated userParameters due to a pre 4.1 replication bug"""
        self.report("ERROR: incorrect userParameters value on object %s (odd length).  If you have another working DC that does not give this warning, please run 'samba-tool drs replicate --full-sync --local <destinationDC> <sourceDC> %s'" % (obj.dn, self.samdb.get_nc_root(obj.dn)))

    def find_revealed_link(self, dn, attrname, guid):
        '''return a revealed link in an object'''
        res = self.samdb.search(base=dn, scope=ldb.SCOPE_BASE, attrs=[attrname],
                                controls=["show_deleted:0", "extended_dn:0", "reveal_internals:0"])
        syntax_oid = self.samdb_schema.get_syntax_oid_from_lDAPDisplayName(attrname)
        for val in res[0][attrname]:
            dsdb_dn = dsdb_Dn(self.samdb, val.decode('utf8'), syntax_oid)
            guid2 = dsdb_dn.dn.get_extended_component("GUID")
            if guid == guid2:
                return dsdb_dn
        return None

    def check_duplicate_links(self, obj, forward_attr, forward_syntax, forward_linkID, backlink_attr):
        '''check a linked values for duplicate forward links'''
        error_count = 0

        duplicate_dict = dict()
        unique_dict = dict()

        # Only forward links can have this problem
        if forward_linkID & 1:
            # If we got the reverse, skip it
            return (error_count, duplicate_dict, unique_dict)

        if backlink_attr is None:
            return (error_count, duplicate_dict, unique_dict)

        duplicate_cache_key = "%s:%s" % (str(obj.dn), forward_attr)
        if duplicate_cache_key not in self.duplicate_link_cache:
            self.duplicate_link_cache[duplicate_cache_key] = False

        for val in obj[forward_attr]:
            dsdb_dn = dsdb_Dn(self.samdb, val.decode('utf8'), forward_syntax)

            # all DNs should have a GUID component
            guid = dsdb_dn.dn.get_extended_component("GUID")
            if guid is None:
                continue
            guidstr = str(misc.GUID(guid))
            keystr = guidstr + dsdb_dn.prefix
            if keystr not in unique_dict:
                unique_dict[keystr] = dsdb_dn
                continue
            error_count += 1
            if keystr not in duplicate_dict:
                duplicate_dict[keystr] = dict()
                duplicate_dict[keystr]["keep"] = None
                duplicate_dict[keystr]["delete"] = list()

            # Now check for the highest RMD_VERSION
            v1 = int(unique_dict[keystr].dn.get_extended_component("RMD_VERSION"))
            v2 = int(dsdb_dn.dn.get_extended_component("RMD_VERSION"))
            if v1 > v2:
                duplicate_dict[keystr]["keep"] = unique_dict[keystr]
                duplicate_dict[keystr]["delete"].append(dsdb_dn)
                continue
            if v1 < v2:
                duplicate_dict[keystr]["keep"] = dsdb_dn
                duplicate_dict[keystr]["delete"].append(unique_dict[keystr])
                unique_dict[keystr] = dsdb_dn
                continue
            # Fallback to the highest RMD_LOCAL_USN
            u1 = int(unique_dict[keystr].dn.get_extended_component("RMD_LOCAL_USN"))
            u2 = int(dsdb_dn.dn.get_extended_component("RMD_LOCAL_USN"))
            if u1 >= u2:
                duplicate_dict[keystr]["keep"] = unique_dict[keystr]
                duplicate_dict[keystr]["delete"].append(dsdb_dn)
                continue
            duplicate_dict[keystr]["keep"] = dsdb_dn
            duplicate_dict[keystr]["delete"].append(unique_dict[keystr])
            unique_dict[keystr] = dsdb_dn

        if error_count != 0:
            self.duplicate_link_cache[duplicate_cache_key] = True

        return (error_count, duplicate_dict, unique_dict)

    def has_duplicate_links(self, dn, forward_attr, forward_syntax):
        '''check a linked values for duplicate forward links'''
        error_count = 0

        duplicate_cache_key = "%s:%s" % (str(dn), forward_attr)
        if duplicate_cache_key in self.duplicate_link_cache:
            return self.duplicate_link_cache[duplicate_cache_key]

        forward_linkID, backlink_attr = self.get_attr_linkID_and_reverse_name(forward_attr)

        attrs = [forward_attr]
        controls = ["extended_dn:1:1", "reveal_internals:0"]

        # check its the right GUID
        try:
            res = self.samdb.search(base=str(dn), scope=ldb.SCOPE_BASE,
                                    attrs=attrs, controls=controls)
        except ldb.LdbError as e8:
            (enum, estr) = e8.args
            if enum != ldb.ERR_NO_SUCH_OBJECT:
                raise

            return False

        obj = res[0]
        error_count, duplicate_dict, unique_dict = \
            self.check_duplicate_links(obj, forward_attr, forward_syntax, forward_linkID, backlink_attr)

        if duplicate_cache_key in self.duplicate_link_cache:
            return self.duplicate_link_cache[duplicate_cache_key]

        return False

    def find_missing_forward_links_from_backlinks(self, obj,
                                                  forward_attr,
                                                  forward_syntax,
                                                  backlink_attr,
                                                  forward_unique_dict):
        '''Find all backlinks linking to obj_guid_str not already in forward_unique_dict'''
        missing_forward_links = []
        error_count = 0

        if backlink_attr is None:
            return (missing_forward_links, error_count)

        if forward_syntax != ldb.SYNTAX_DN:
            self.report("Not checking for missing forward links for syntax: %s" %
                        forward_syntax)
            return (missing_forward_links, error_count)

        if "sortedLinks" in self.compatibleFeatures:
            self.report("Not checking for missing forward links because the db " +
                        "has the sortedLinks feature")
            return (missing_forward_links, error_count)

        try:
            obj_guid = obj['objectGUID'][0]
            obj_guid_str = str(ndr_unpack(misc.GUID, obj_guid))
            filter = "(%s=<GUID=%s>)" % (backlink_attr, obj_guid_str)

            res = self.samdb.search(expression=filter,
                                    scope=ldb.SCOPE_SUBTREE, attrs=["objectGUID"],
                                    controls=["extended_dn:1:1",
                                              "search_options:1:2",
                                              "paged_results:1:1000"])
        except ldb.LdbError as e9:
            (enum, estr) = e9.args
            raise

        for r in res:
            target_dn = dsdb_Dn(self.samdb, r.dn.extended_str(), forward_syntax)

            guid = target_dn.dn.get_extended_component("GUID")
            guidstr = str(misc.GUID(guid))
            if guidstr in forward_unique_dict:
                continue

            # A valid forward link looks like this:
            #
            #    <GUID=9f92d30a-fc23-11e4-a5f6-30be15454808>;
            #    <RMD_ADDTIME=131607546230000000>;
            #    <RMD_CHANGETIME=131607546230000000>;
            #    <RMD_FLAGS=0>;
            #    <RMD_INVOCID=4e4496a3-7fb8-4f97-8a33-d238db8b5e2d>;
            #    <RMD_LOCAL_USN=3765>;
            #    <RMD_ORIGINATING_USN=3765>;
            #    <RMD_VERSION=1>;
            #    <SID=S-1-5-21-4177067393-1453636373-93818738-1124>;
            #    CN=unsorted-u8,CN=Users,DC=release-4-5-0-pre1,DC=samba,DC=corp
            #
            # Note that versions older than Samba 4.8 create
            # links with RMD_VERSION=0.
            #
            # Try to get the local_usn and time from objectClass
            # if possible and fallback to any other one.
            repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob,
                              obj['replPropertyMetadata'][0])
            for o in repl.ctr.array:
                local_usn = o.local_usn
                t = o.originating_change_time
                if o.attid == drsuapi.DRSUAPI_ATTID_objectClass:
                    break

            # We use a magic invocationID for restoring missing
            # forward links to recover from bug #13228.
            # This should allow some more future magic to fix the
            # problem.
            #
            # It also means it looses the conflict resolution
            # against almost every real invocation, if the
            # version is also 0.
            originating_invocid = misc.GUID("ffffffff-4700-4700-4700-000000b13228")
            originating_usn = 1

            rmd_addtime = t
            rmd_changetime = t
            rmd_flags = 0
            rmd_invocid = originating_invocid
            rmd_originating_usn = originating_usn
            rmd_local_usn = local_usn
            rmd_version = 0

            target_dn.dn.set_extended_component("RMD_ADDTIME", str(rmd_addtime))
            target_dn.dn.set_extended_component("RMD_CHANGETIME", str(rmd_changetime))
            target_dn.dn.set_extended_component("RMD_FLAGS", str(rmd_flags))
            target_dn.dn.set_extended_component("RMD_INVOCID", ndr_pack(rmd_invocid))
            target_dn.dn.set_extended_component("RMD_ORIGINATING_USN", str(rmd_originating_usn))
            target_dn.dn.set_extended_component("RMD_LOCAL_USN", str(rmd_local_usn))
            target_dn.dn.set_extended_component("RMD_VERSION", str(rmd_version))

            error_count += 1
            missing_forward_links.append(target_dn)

        return (missing_forward_links, error_count)

    def check_dn(self, obj, attrname, syntax_oid):
        '''check a DN attribute for correctness'''
        error_count = 0
        obj_guid = obj['objectGUID'][0]

        linkID, reverse_link_name = self.get_attr_linkID_and_reverse_name(attrname)
        if reverse_link_name is not None:
            reverse_syntax_oid = self.samdb_schema.get_syntax_oid_from_lDAPDisplayName(reverse_link_name)
        else:
            reverse_syntax_oid = None

        is_member_link = attrname in ("member", "memberOf")
        if is_member_link and self.quick_membership_checks:
            duplicate_dict = {}
        else:
            error_count, duplicate_dict, unique_dict = \
                self.check_duplicate_links(obj, attrname, syntax_oid,
                                           linkID, reverse_link_name)

        if len(duplicate_dict) != 0:

            missing_forward_links, missing_error_count = \
                self.find_missing_forward_links_from_backlinks(obj,
                                                               attrname, syntax_oid,
                                                               reverse_link_name,
                                                               unique_dict)
            error_count += missing_error_count

            forward_links = [dn for dn in unique_dict.values()]

            if missing_error_count != 0:
                self.report("ERROR: Missing and duplicate forward link values for attribute '%s' in '%s'" % (
                            attrname, obj.dn))
            else:
                self.report("ERROR: Duplicate forward link values for attribute '%s' in '%s'" % (attrname, obj.dn))
            for m in missing_forward_links:
                self.report("Missing   link '%s'" % (m))
                if not self.confirm_all("Schedule readding missing forward link for attribute %s" % attrname,
                                        'fix_all_missing_forward_links'):
                    self.err_orphaned_backlink(m.dn, reverse_link_name,
                                               obj.dn.extended_str(), obj.dn,
                                               attrname, syntax_oid,
                                               check_duplicates=False)
                    continue
                forward_links += [m]
            for keystr in duplicate_dict.keys():
                d = duplicate_dict[keystr]
                for dd in d["delete"]:
                    self.report("Duplicate link '%s'" % dd)
                self.report("Correct   link '%s'" % d["keep"])

            # We now construct the sorted dn values.
            # They're sorted by the objectGUID of the target
            # See dsdb_Dn.__cmp__()
            vals = [str(dn) for dn in sorted(forward_links)]
            self.err_recover_forward_links(obj, attrname, vals)
            # We should continue with the fixed values
            obj[attrname] = ldb.MessageElement(vals, 0, attrname)

        for val in obj[attrname]:
            dsdb_dn = dsdb_Dn(self.samdb, val.decode('utf8'), syntax_oid)

            # all DNs should have a GUID component
            guid = dsdb_dn.dn.get_extended_component("GUID")
            if guid is None:
                error_count += 1
                self.err_missing_dn_GUID_component(obj.dn, attrname, val, dsdb_dn,
                                                   "missing GUID")
                continue

            guidstr = str(misc.GUID(guid))
            attrs = ['isDeleted', 'replPropertyMetaData']

            if (str(attrname).lower() == 'msds-hasinstantiatedncs') and (obj.dn == self.ntds_dsa):
                fixing_msDS_HasInstantiatedNCs = True
                attrs.append("instanceType")
            else:
                fixing_msDS_HasInstantiatedNCs = False

            if reverse_link_name is not None:
                attrs.append(reverse_link_name)

            # check its the right GUID
            try:
                res = self.samdb.search(base="<GUID=%s>" % guidstr, scope=ldb.SCOPE_BASE,
                                        attrs=attrs, controls=["extended_dn:1:1", "show_recycled:1",
                                                               "reveal_internals:0"
                                                               ])
            except ldb.LdbError as e3:
                (enum, estr) = e3.args
                if enum != ldb.ERR_NO_SUCH_OBJECT:
                    raise

                # We don't always want to
                error_count += self.err_missing_target_dn_or_GUID(obj.dn,
                                                                  attrname,
                                                                  val,
                                                                  dsdb_dn)
                continue

            if fixing_msDS_HasInstantiatedNCs:
                dsdb_dn.prefix = "B:8:%08X:" % int(res[0]['instanceType'][0])
                dsdb_dn.binary = "%08X" % int(res[0]['instanceType'][0])

                if str(dsdb_dn) != str(val):
                    error_count += 1
                    self.err_incorrect_binary_dn(obj.dn, attrname, val, dsdb_dn, "incorrect instanceType part of Binary DN")
                    continue

            # now we have two cases - the source object might or might not be deleted
            is_deleted = 'isDeleted' in obj and str(obj['isDeleted'][0]).upper() == 'TRUE'
            target_is_deleted = 'isDeleted' in res[0] and str(res[0]['isDeleted'][0]).upper() == 'TRUE'

            if is_deleted and obj.dn not in self.deleted_objects_containers and linkID:
                # A fully deleted object should not have any linked
                # attributes. (MS-ADTS 3.1.1.5.5.1.1 Tombstone
                # Requirements and 3.1.1.5.5.1.3 Recycled-Object
                # Requirements)
                self.err_undead_linked_attribute(obj, attrname, val)
                error_count += 1
                continue
            elif target_is_deleted and not self.is_deleted_objects_dn(dsdb_dn) and linkID:
                # the target DN is not allowed to be deleted, unless the target DN is the
                # special Deleted Objects container
                error_count += 1
                local_usn = dsdb_dn.dn.get_extended_component("RMD_LOCAL_USN")
                if local_usn:
                    if 'replPropertyMetaData' in res[0]:
                        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob,
                                          res[0]['replPropertyMetadata'][0])
                        found_data = False
                        for o in repl.ctr.array:
                            if o.attid == drsuapi.DRSUAPI_ATTID_isDeleted:
                                deleted_usn = o.local_usn
                                if deleted_usn >= int(local_usn):
                                    # If the object was deleted after the link
                                    # was last modified then, clean it up here
                                    found_data = True
                                    break

                        if found_data:
                            self.err_deleted_dn(obj.dn, attrname,
                                                val, dsdb_dn, res[0].dn, True)
                            continue

                self.err_deleted_dn(obj.dn, attrname, val, dsdb_dn, res[0].dn, False)
                continue

            # We should not check for incorrect
            # components on deleted links, as these are allowed to
            # go stale (we just need the GUID, not the name)
            rmd_blob = dsdb_dn.dn.get_extended_component("RMD_FLAGS")
            rmd_flags = 0
            if rmd_blob is not None:
                rmd_flags = int(rmd_blob)

            # assert the DN matches in string form, where a reverse
            # link exists, otherwise (below) offer to fix it as a non-error.
            # The string form is essentially only kept for forensics,
            # as we always re-resolve by GUID in normal operations.
            if not rmd_flags & 1 and reverse_link_name is not None:
                if str(res[0].dn) != str(dsdb_dn.dn):
                    error_count += 1
                    self.err_dn_component_target_mismatch(obj.dn, attrname, val, dsdb_dn,
                                                          res[0].dn, "string")
                    continue

            if res[0].dn.get_extended_component("GUID") != dsdb_dn.dn.get_extended_component("GUID"):
                error_count += 1
                self.err_dn_component_target_mismatch(obj.dn, attrname, val, dsdb_dn,
                                                      res[0].dn, "GUID")
                continue

            target_sid = res[0].dn.get_extended_component("SID")
            link_sid = dsdb_dn.dn.get_extended_component("SID")
            if link_sid is None and target_sid is not None:
                error_count += 1
                self.err_dn_component_missing_target_sid(obj.dn, attrname, val,
                                                         dsdb_dn, target_sid)
                continue
            if link_sid != target_sid:
                error_count += 1
                self.err_dn_component_target_mismatch(obj.dn, attrname, val, dsdb_dn,
                                                      res[0].dn, "SID")
                continue

            # Only for non-links, not even forward-only links
            # (otherwise this breaks repl_meta_data):
            #
            # Now we have checked the GUID and SID, offer to fix old
            # DN strings as a non-error (DNs, not links so no
            # backlink).  Samba does not maintain this string
            # otherwise, so we don't increment error_count.
            if reverse_link_name is None:
                if linkID == 0 and str(res[0].dn) != str(dsdb_dn.dn):
                    # Pass in the old/bad DN without the <GUID=...> part,
                    # otherwise the LDB code will correct it on the way through
                    # (Note: we still want to preserve the DSDB DN prefix in the
                    # case of binary DNs)
                    bad_dn = dsdb_dn.prefix + dsdb_dn.dn.get_linearized()
                    self.err_dn_string_component_old(obj.dn, attrname, bad_dn,
                                                     dsdb_dn, res[0].dn)
                continue

            if is_member_link and self.quick_membership_checks:
                continue

            # check the reverse_link is correct if there should be one
            match_count = 0
            if reverse_link_name in res[0]:
                for v in res[0][reverse_link_name]:
                    v_dn = dsdb_Dn(self.samdb, v.decode('utf8'))
                    v_guid = v_dn.dn.get_extended_component("GUID")
                    v_blob = v_dn.dn.get_extended_component("RMD_FLAGS")
                    v_rmd_flags = 0
                    if v_blob is not None:
                        v_rmd_flags = int(v_blob)
                    if v_rmd_flags & 1:
                        continue
                    if v_guid == obj_guid:
                        match_count += 1

            if match_count != 1:
                if syntax_oid == dsdb.DSDB_SYNTAX_BINARY_DN or reverse_syntax_oid == dsdb.DSDB_SYNTAX_BINARY_DN:
                    if not linkID & 1:
                        # Forward binary multi-valued linked attribute
                        forward_count = 0
                        for w in obj[attrname]:
                            w_guid = dsdb_Dn(self.samdb, w.decode('utf8')).dn.get_extended_component("GUID")
                            if w_guid == guid:
                                forward_count += 1

                        if match_count == forward_count:
                            continue
            expected_count = 0
            for v in obj[attrname]:
                v_dn = dsdb_Dn(self.samdb, v.decode('utf8'))
                v_guid = v_dn.dn.get_extended_component("GUID")
                v_blob = v_dn.dn.get_extended_component("RMD_FLAGS")
                v_rmd_flags = 0
                if v_blob is not None:
                    v_rmd_flags = int(v_blob)
                if v_rmd_flags & 1:
                    continue
                if v_guid == guid:
                    expected_count += 1

            if match_count == expected_count:
                continue

            diff_count = expected_count - match_count

            if linkID & 1:
                # If there's a backward link on binary multi-valued linked attribute,
                # let the check on the forward link remedy the value.
                # UNLESS, there is no forward link detected.
                if match_count == 0:
                    error_count += 1
                    self.err_orphaned_backlink(obj.dn, attrname,
                                               val, dsdb_dn.dn,
                                               reverse_link_name,
                                               reverse_syntax_oid)
                    continue
                # Only warn here and let the forward link logic fix it.
                self.report("WARNING: Link (back) mismatch for '%s' (%d) on '%s' to '%s' (%d) on '%s'" % (
                            attrname, expected_count, str(obj.dn),
                            reverse_link_name, match_count, str(dsdb_dn.dn)))
                continue

            assert not target_is_deleted

            self.report("ERROR: Link (forward) mismatch for '%s' (%d) on '%s' to '%s' (%d) on '%s'" % (
                        attrname, expected_count, str(obj.dn),
                        reverse_link_name, match_count, str(dsdb_dn.dn)))

            # Loop until the difference between the forward and
            # the backward links is resolved.
            while diff_count != 0:
                error_count += 1
                if diff_count > 0:
                    if match_count > 0 or diff_count > 1:
                        # TODO no method to fix these right now
                        self.report("ERROR: Can't fix missing "
                                    "multi-valued backlinks on %s" % str(dsdb_dn.dn))
                        break
                    self.err_missing_backlink(obj, attrname,
                                              obj.dn.extended_str(),
                                              reverse_link_name,
                                              dsdb_dn.dn)
                    diff_count -= 1
                else:
                    self.err_orphaned_backlink(res[0].dn, reverse_link_name,
                                               obj.dn.extended_str(), obj.dn,
                                               attrname, syntax_oid)
                    diff_count += 1

        return error_count

    def find_repl_attid(self, repl, attid):
        for o in repl.ctr.array:
            if o.attid == attid:
                return o

        return None

    def get_originating_time(self, val, attid):
        '''Read metadata properties and return the originating time for
           a given attributeId.

           :return: the originating time or 0 if not found
        '''

        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob, val)
        o = self.find_repl_attid(repl, attid)
        if o is not None:
            return o.originating_change_time
        return 0

    def process_metadata(self, dn, val):
        '''Read metadata properties and list attributes in it.
           raises KeyError if the attid is unknown.'''

        set_att = set()
        wrong_attids = set()
        list_attid = []
        in_schema_nc = dn.is_child_of(self.schema_dn)

        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob, val)

        for o in repl.ctr.array:
            att = self.samdb_schema.get_lDAPDisplayName_by_attid(o.attid)
            set_att.add(att.lower())
            list_attid.append(o.attid)
            correct_attid = self.samdb_schema.get_attid_from_lDAPDisplayName(att,
                                                                             is_schema_nc=in_schema_nc)
            if correct_attid != o.attid:
                wrong_attids.add(o.attid)

        return (set_att, list_attid, wrong_attids)

    def fix_metadata(self, obj, attr):
        '''re-write replPropertyMetaData elements for a single attribute for a
        object. This is used to fix missing replPropertyMetaData elements'''
        guid_str = str(ndr_unpack(misc.GUID, obj['objectGUID'][0]))
        dn = ldb.Dn(self.samdb, "<GUID=%s>" % guid_str)
        res = self.samdb.search(base=dn, scope=ldb.SCOPE_BASE, attrs=[attr],
                                controls=["search_options:1:2",
                                          "show_recycled:1"])
        msg = res[0]
        nmsg = ldb.Message()
        nmsg.dn = dn
        nmsg[attr] = ldb.MessageElement(msg[attr], ldb.FLAG_MOD_REPLACE, attr)
        if self.do_modify(nmsg, ["relax:0", "provision:0", "show_recycled:1"],
                          "Failed to fix metadata for attribute %s" % attr):
            self.report("Fixed metadata for attribute %s" % attr)

    def ace_get_effective_inherited_type(self, ace):
        if ace.flags & security.SEC_ACE_FLAG_INHERIT_ONLY:
            return None

        check = False
        if ace.type == security.SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
            check = True
        elif ace.type == security.SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
            check = True
        elif ace.type == security.SEC_ACE_TYPE_SYSTEM_AUDIT_OBJECT:
            check = True
        elif ace.type == security.SEC_ACE_TYPE_SYSTEM_ALARM_OBJECT:
            check = True

        if not check:
            return None

        if not ace.object.flags & security.SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT:
            return None

        return str(ace.object.inherited_type)

    def lookup_class_schemaIDGUID(self, cls):
        if cls in self.class_schemaIDGUID:
            return self.class_schemaIDGUID[cls]

        flt = "(&(ldapDisplayName=%s)(objectClass=classSchema))" % cls
        res = self.samdb.search(base=self.schema_dn,
                                expression=flt,
                                attrs=["schemaIDGUID"])
        t = str(ndr_unpack(misc.GUID, res[0]["schemaIDGUID"][0]))

        self.class_schemaIDGUID[cls] = t
        return t

    def process_sd(self, dn, obj):
        sd_attr = "nTSecurityDescriptor"
        sd_val = obj[sd_attr]

        sd = ndr_unpack(security.descriptor, sd_val[0])

        is_deleted = 'isDeleted' in obj and str(obj['isDeleted'][0]).upper() == 'TRUE'
        if is_deleted:
            # we don't fix deleted objects
            return (sd, None)

        sd_clean = security.descriptor()
        sd_clean.owner_sid = sd.owner_sid
        sd_clean.group_sid = sd.group_sid
        sd_clean.type = sd.type
        sd_clean.revision = sd.revision

        broken = False
        last_inherited_type = None

        aces = []
        if sd.sacl is not None:
            aces = sd.sacl.aces
        for i in range(0, len(aces)):
            ace = aces[i]

            if not ace.flags & security.SEC_ACE_FLAG_INHERITED_ACE:
                sd_clean.sacl_add(ace)
                continue

            t = self.ace_get_effective_inherited_type(ace)
            if t is None:
                continue

            if last_inherited_type is not None:
                if t != last_inherited_type:
                    # if it inherited from more than
                    # one type it's very likely to be broken
                    #
                    # If not the recalculation will calculate
                    # the same result.
                    broken = True
                continue

            last_inherited_type = t

        aces = []
        if sd.dacl is not None:
            aces = sd.dacl.aces
        for i in range(0, len(aces)):
            ace = aces[i]

            if not ace.flags & security.SEC_ACE_FLAG_INHERITED_ACE:
                sd_clean.dacl_add(ace)
                continue

            t = self.ace_get_effective_inherited_type(ace)
            if t is None:
                continue

            if last_inherited_type is not None:
                if t != last_inherited_type:
                    # if it inherited from more than
                    # one type it's very likely to be broken
                    #
                    # If not the recalculation will calculate
                    # the same result.
                    broken = True
                continue

            last_inherited_type = t

        if broken:
            return (sd_clean, sd)

        if last_inherited_type is None:
            # ok
            return (sd, None)

        cls = None
        try:
            cls = obj["objectClass"][-1]
        except KeyError as e:
            pass

        if cls is None:
            res = self.samdb.search(base=dn, scope=ldb.SCOPE_BASE,
                                    attrs=["isDeleted", "objectClass"],
                                    controls=["show_recycled:1"])
            o = res[0]
            is_deleted = 'isDeleted' in o and str(o['isDeleted'][0]).upper() == 'TRUE'
            if is_deleted:
                # we don't fix deleted objects
                return (sd, None)
            cls = o["objectClass"][-1]

        t = self.lookup_class_schemaIDGUID(cls)

        if t != last_inherited_type:
            # broken
            return (sd_clean, sd)

        # ok
        return (sd, None)

    def err_wrong_sd(self, dn, sd, sd_broken):
        '''re-write the SD due to incorrect inherited ACEs'''
        sd_attr = "nTSecurityDescriptor"
        sd_val = ndr_pack(sd)
        sd_flags = security.SECINFO_DACL | security.SECINFO_SACL

        if not self.confirm_all('Fix %s on %s?' % (sd_attr, dn), 'fix_ntsecuritydescriptor'):
            self.report('Not fixing %s on %s\n' % (sd_attr, dn))
            return

        nmsg = ldb.Message()
        nmsg.dn = dn
        nmsg[sd_attr] = ldb.MessageElement(sd_val, ldb.FLAG_MOD_REPLACE, sd_attr)
        if self.do_modify(nmsg, ["sd_flags:1:%d" % sd_flags],
                          "Failed to fix attribute %s" % sd_attr):
            self.report("Fixed attribute '%s' of '%s'\n" % (sd_attr, dn))

    def err_wrong_default_sd(self, dn, sd, diff):
        '''re-write the SD due to not matching the default (optional mode for fixing an incorrect provision)'''
        sd_attr = "nTSecurityDescriptor"
        sd_val = ndr_pack(sd)
        sd_flags = security.SECINFO_DACL | security.SECINFO_SACL
        if sd.owner_sid is not None:
            sd_flags |= security.SECINFO_OWNER
        if sd.group_sid is not None:
            sd_flags |= security.SECINFO_GROUP

        if not self.confirm_all('Reset %s on %s back to provision default?\n%s' % (sd_attr, dn, diff), 'reset_all_well_known_acls'):
            self.report('Not resetting %s on %s\n' % (sd_attr, dn))
            return

        m = ldb.Message()
        m.dn = dn
        m[sd_attr] = ldb.MessageElement(sd_val, ldb.FLAG_MOD_REPLACE, sd_attr)
        if self.do_modify(m, ["sd_flags:1:%d" % sd_flags],
                          "Failed to reset attribute %s" % sd_attr):
            self.report("Fixed attribute '%s' of '%s'\n" % (sd_attr, dn))

    def err_missing_sd_owner(self, dn, sd):
        '''re-write the SD due to a missing owner or group'''
        sd_attr = "nTSecurityDescriptor"
        sd_val = ndr_pack(sd)
        sd_flags = security.SECINFO_OWNER | security.SECINFO_GROUP

        if not self.confirm_all('Fix missing owner or group in %s on %s?' % (sd_attr, dn), 'fix_ntsecuritydescriptor_owner_group'):
            self.report('Not fixing missing owner or group %s on %s\n' % (sd_attr, dn))
            return

        nmsg = ldb.Message()
        nmsg.dn = dn
        nmsg[sd_attr] = ldb.MessageElement(sd_val, ldb.FLAG_MOD_REPLACE, sd_attr)

        # By setting the session_info to admin_session_info and
        # setting the security.SECINFO_OWNER | security.SECINFO_GROUP
        # flags we cause the descriptor module to set the correct
        # owner and group on the SD, replacing the None/NULL values
        # for owner_sid and group_sid currently present.
        #
        # The admin_session_info matches that used in provision, and
        # is the best guess we can make for an existing object that
        # hasn't had something specifically set.
        #
        # This is important for the dns related naming contexts.
        self.samdb.set_session_info(self.admin_session_info)
        if self.do_modify(nmsg, ["sd_flags:1:%d" % sd_flags],
                          "Failed to fix metadata for attribute %s" % sd_attr):
            self.report("Fixed attribute '%s' of '%s'\n" % (sd_attr, dn))
        self.samdb.set_session_info(self.system_session_info)

    def is_expired_tombstone(self, dn, repl_val):
        if self.check_expired_tombstones:
            # This is not the default, it's just
            # used to keep dbcheck tests work with
            # old static provision dumps
            return False

        if dn in self.deleted_objects_containers:
            # The Deleted Objects container will look like an expired
            # tombstone
            return False

        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob, repl_val)

        isDeleted = self.find_repl_attid(repl, drsuapi.DRSUAPI_ATTID_isDeleted)

        delete_time = samba.nttime2unix(isDeleted.originating_change_time)
        current_time = time.time()

        tombstone_delta = self.tombstoneLifetime * (24 * 60 * 60)

        delta = current_time - delete_time
        if delta <= tombstone_delta:
            return False

        expunge_time = delete_time + tombstone_delta

        delta_days = delta / (24 * 60 * 60)

        if delta_days <= 2:
            self.report("SKIPPING additional checks on object "
                        "%s which very recently "
                        "became an expired tombstone (normal)" % dn)
            self.report("INFO: it is expected this will be expunged "
                        "by the next daily task some time after %s, "
                        "%d hours ago"
                        % (time.ctime(expunge_time), delta // (60 * 60)))
        else:
            self.report("SKIPPING: object %s is an expired tombstone" % dn)
            self.report("INFO: it was expected this object would have "
                        "been expunged soon after"
                        "%s, %d days ago"
                        % (time.ctime(expunge_time), delta_days))

        self.report("isDeleted: attid=0x%08x version=%d invocation=%s usn=%s (local=%s) at %s" % (
                    isDeleted.attid,
                    isDeleted.version,
                    isDeleted.originating_invocation_id,
                    isDeleted.originating_usn,
                    isDeleted.local_usn,
                    time.ctime(samba.nttime2unix(isDeleted.originating_change_time))))
        self.expired_tombstones += 1
        return True

    def find_changes_after_deletion(self, repl_val):
        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob, repl_val)

        isDeleted = self.find_repl_attid(repl, drsuapi.DRSUAPI_ATTID_isDeleted)

        delete_time = samba.nttime2unix(isDeleted.originating_change_time)

        tombstone_delta = self.tombstoneLifetime * (24 * 60 * 60)

        found = []
        for o in repl.ctr.array:
            if o.attid == drsuapi.DRSUAPI_ATTID_isDeleted:
                continue

            if o.local_usn <= isDeleted.local_usn:
                continue

            if o.originating_change_time <= isDeleted.originating_change_time:
                continue

            change_time = samba.nttime2unix(o.originating_change_time)

            delta = change_time - delete_time
            if delta <= tombstone_delta:
                continue

            # If the modification happened after the tombstone lifetime
            # has passed, we have a bug as the object might be deleted
            # already on other DCs and won't be able to replicate
            # back
            found.append(o)

        return found, isDeleted

    def has_changes_after_deletion(self, dn, repl_val):
        found, isDeleted = self.find_changes_after_deletion(repl_val)
        if len(found) == 0:
            return False

        def report_attid(o):
            try:
                attname = self.samdb_schema.get_lDAPDisplayName_by_attid(o.attid)
            except KeyError:
                attname = "<unknown:0x%x08x>" % o.attid

            self.report("%s: attid=0x%08x version=%d invocation=%s usn=%s (local=%s) at %s" % (
                        attname, o.attid, o.version,
                        o.originating_invocation_id,
                        o.originating_usn,
                        o.local_usn,
                        time.ctime(samba.nttime2unix(o.originating_change_time))))

        self.report("ERROR: object %s, has changes after deletion" % dn)
        report_attid(isDeleted)
        for o in found:
            report_attid(o)

        return True

    def err_changes_after_deletion(self, dn, repl_val):
        found, isDeleted = self.find_changes_after_deletion(repl_val)

        in_schema_nc = dn.is_child_of(self.schema_dn)
        rdn_attr = dn.get_rdn_name()
        rdn_attid = self.samdb_schema.get_attid_from_lDAPDisplayName(rdn_attr,
                                                     is_schema_nc=in_schema_nc)

        unexpected = []
        for o in found:
            if o.attid == rdn_attid:
                continue
            if o.attid == drsuapi.DRSUAPI_ATTID_name:
                continue
            if o.attid == drsuapi.DRSUAPI_ATTID_lastKnownParent:
                continue
            try:
                attname = self.samdb_schema.get_lDAPDisplayName_by_attid(o.attid)
            except KeyError:
                attname = "<unknown:0x%x08x>" % o.attid
            unexpected.append(attname)

        if len(unexpected) > 0:
            self.report('Unexpeted attributes: %s' % ",".join(unexpected))
            self.report('Not fixing changes after deletion bug')
            return

        if not self.confirm_all('Delete broken tombstone object %s deleted %s days ago?' % (
                                dn, self.tombstoneLifetime), 'fix_changes_after_deletion_bug'):
            self.report('Not fixing changes after deletion bug')
            return

        if self.do_delete(dn, ["relax:0"],
                          "Failed to remove DN %s" % dn):
            self.report("Removed DN %s" % dn)

    def has_replmetadata_zero_invocationid(self, dn, repl_meta_data):
        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob,
                          repl_meta_data)
        ctr = repl.ctr
        found = False
        for o in ctr.array:
            # Search for a zero invocationID
            if o.originating_invocation_id != misc.GUID("00000000-0000-0000-0000-000000000000"):
                continue

            found = True
            self.report('''ERROR: on replPropertyMetaData of %s, the instanceType on attribute 0x%08x,
                           version %d changed at %s is 00000000-0000-0000-0000-000000000000,
                           but should be non-zero.  Proposed fix is to set to our invocationID (%s).'''
                        % (dn, o.attid, o.version,
                           time.ctime(samba.nttime2unix(o.originating_change_time)),
                           self.samdb.get_invocation_id()))

        return found

    def err_replmetadata_zero_invocationid(self, dn, attr, repl_meta_data):
        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob,
                          repl_meta_data)
        ctr = repl.ctr
        now = samba.unix2nttime(int(time.time()))
        found = False
        for o in ctr.array:
            # Search for a zero invocationID
            if o.originating_invocation_id != misc.GUID("00000000-0000-0000-0000-000000000000"):
                continue

            found = True
            seq = self.samdb.sequence_number(ldb.SEQ_NEXT)
            o.version = o.version + 1
            o.originating_change_time = now
            o.originating_invocation_id = misc.GUID(self.samdb.get_invocation_id())
            o.originating_usn = seq
            o.local_usn = seq

        if found:
            replBlob = ndr_pack(repl)
            msg = ldb.Message()
            msg.dn = dn

            if not self.confirm_all('Fix %s on %s by setting originating_invocation_id on some elements to our invocationID %s?'
                                    % (attr, dn, self.samdb.get_invocation_id()), 'fix_replmetadata_zero_invocationid'):
                self.report('Not fixing zero originating_invocation_id in %s on %s\n' % (attr, dn))
                return

            nmsg = ldb.Message()
            nmsg.dn = dn
            nmsg[attr] = ldb.MessageElement(replBlob, ldb.FLAG_MOD_REPLACE, attr)
            if self.do_modify(nmsg, ["local_oid:%s:0" % dsdb.DSDB_CONTROL_DBCHECK_MODIFY_RO_REPLICA,
                                     "local_oid:1.3.6.1.4.1.7165.4.3.14:0"],
                              "Failed to fix attribute %s" % attr):
                self.report("Fixed attribute '%s' of '%s'\n" % (attr, dn))

    def err_replmetadata_unknown_attid(self, dn, attr, repl_meta_data):
        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob,
                          repl_meta_data)
        ctr = repl.ctr
        for o in ctr.array:
            # Search for an invalid attid
            try:
                att = self.samdb_schema.get_lDAPDisplayName_by_attid(o.attid)
            except KeyError:
                self.report('ERROR: attributeID 0X%0X is not known in our schema, not fixing %s on %s\n' % (o.attid, attr, dn))
                return

    def err_replmetadata_incorrect_attid(self, dn, attr, repl_meta_data, wrong_attids):
        repl = ndr_unpack(drsblobs.replPropertyMetaDataBlob,
                          repl_meta_data)
        fix = False

        set_att = set()
        remove_attid = set()
        hash_att = {}

        in_schema_nc = dn.is_child_of(self.schema_dn)

        ctr = repl.ctr
        # Sort the array, except for the last element.  This strange
        # construction, creating a new list, due to bugs in samba's
        # array handling in IDL generated objects.
        ctr.array = sorted(ctr.array[:], key=lambda o: o.attid)
        # Now walk it in reverse, so we see the low (and so incorrect,
        # the correct values are above 0x80000000) values first and
        # remove the 'second' value we see.
        for o in reversed(ctr.array):
            print("%s: 0x%08x" % (dn, o.attid))
            att = self.samdb_schema.get_lDAPDisplayName_by_attid(o.attid)
            if att.lower() in set_att:
                self.report('ERROR: duplicate attributeID values for %s in %s on %s\n' % (att, attr, dn))
                if not self.confirm_all('Fix %s on %s by removing the duplicate value 0x%08x for %s (keeping 0x%08x)?'
                                        % (attr, dn, o.attid, att, hash_att[att].attid),
                                        'fix_replmetadata_duplicate_attid'):
                    self.report('Not fixing duplicate value 0x%08x for %s in %s on %s\n'
                                % (o.attid, att, attr, dn))
                    return
                fix = True
                remove_attid.add(o.attid)
                # We want to set the metadata for the most recent
                # update to have been applied locally, that is the metadata
                # matching the (eg string) value in the attribute
                if o.local_usn > hash_att[att].local_usn:
                    # This is always what we would have sent over DRS,
                    # because the DRS server will have sent the
                    # msDS-IntID, but with the values from both
                    # attribute entries.
                    hash_att[att].version = o.version
                    hash_att[att].originating_change_time = o.originating_change_time
                    hash_att[att].originating_invocation_id = o.originating_invocation_id
                    hash_att[att].originating_usn = o.originating_usn
                    hash_att[att].local_usn = o.local_usn

                # Do not re-add the value to the set or overwrite the hash value
                continue

            hash_att[att] = o
            set_att.add(att.lower())

        # Generate a real list we can sort on properly
        new_list = [o for o in ctr.array if o.attid not in remove_attid]

        if (len(wrong_attids) > 0):
            for o in new_list:
                if o.attid in wrong_attids:
                    att = self.samdb_schema.get_lDAPDisplayName_by_attid(o.attid)
                    correct_attid = self.samdb_schema.get_attid_from_lDAPDisplayName(att, is_schema_nc=in_schema_nc)
                    self.report('ERROR: incorrect attributeID values in %s on %s\n' % (attr, dn))
                    if not self.confirm_all('Fix %s on %s by replacing incorrect value 0x%08x for %s (new 0x%08x)?'
                                            % (attr, dn, o.attid, att, hash_att[att].attid), 'fix_replmetadata_wrong_attid'):
                        self.report('Not fixing incorrect value 0x%08x with 0x%08x for %s in %s on %s\n'
                                    % (o.attid, correct_attid, att, attr, dn))
                        return
                    fix = True
                    o.attid = correct_attid
            if fix:
                # Sort the array, (we changed the value so must re-sort)
                new_list[:] = sorted(new_list[:], key=lambda o: o.attid)

        # If we did not already need to fix it, then ask about sorting
        if not fix:
            self.report('ERROR: unsorted attributeID values in %s on %s\n' % (attr, dn))
            if not self.confirm_all('Fix %s on %s by sorting the attribute list?'
                                    % (attr, dn), 'fix_replmetadata_unsorted_attid'):
                self.report('Not fixing %s on %s\n' % (attr, dn))
                return

            # The actual sort done is done at the top of the function

        ctr.count = len(new_list)
        ctr.array = new_list
        replBlob = ndr_pack(repl)

        nmsg = ldb.Message()
        nmsg.dn = dn
        nmsg[attr] = ldb.MessageElement(replBlob, ldb.FLAG_MOD_REPLACE, attr)
        if self.do_modify(nmsg, ["local_oid:%s:0" % dsdb.DSDB_CONTROL_DBCHECK_MODIFY_RO_REPLICA,
                                 "local_oid:1.3.6.1.4.1.7165.4.3.14:0",
                                 "local_oid:1.3.6.1.4.1.7165.4.3.25:0"],
                          "Failed to fix attribute %s" % attr):
            self.report("Fixed attribute '%s' of '%s'\n" % (attr, dn))

    def is_deleted_deleted_objects(self, obj):
        faulty = False
        if "description" not in obj:
            self.report("ERROR: description not present on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "showInAdvancedViewOnly" not in obj or str(obj['showInAdvancedViewOnly'][0]).upper() == 'FALSE':
            self.report("ERROR: showInAdvancedViewOnly not present on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "objectCategory" not in obj:
            self.report("ERROR: objectCategory not present on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "isCriticalSystemObject" not in obj or str(obj['isCriticalSystemObject'][0]).upper() == 'FALSE':
            self.report("ERROR: isCriticalSystemObject not present on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "isRecycled" in obj:
            self.report("ERROR: isRecycled present on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "isDeleted" in obj and str(obj['isDeleted'][0]).upper() == 'FALSE':
            self.report("ERROR: isDeleted not set on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "objectClass" not in obj or (len(obj['objectClass']) != 2 or
                                        str(obj['objectClass'][0]) != 'top' or
                                        str(obj['objectClass'][1]) != 'container'):
            self.report("ERROR: objectClass incorrectly set on Deleted Objects container %s" % obj.dn)
            faulty = True
        if "systemFlags" not in obj or str(obj['systemFlags'][0]) != '-1946157056':
            self.report("ERROR: systemFlags incorrectly set on Deleted Objects container %s" % obj.dn)
            faulty = True
        return faulty

    def err_deleted_deleted_objects(self, obj):
        nmsg = ldb.Message()
        nmsg.dn = dn = obj.dn

        if "description" not in obj:
            nmsg["description"] = ldb.MessageElement("Container for deleted objects", ldb.FLAG_MOD_REPLACE, "description")
        if "showInAdvancedViewOnly" not in obj:
            nmsg["showInAdvancedViewOnly"] = ldb.MessageElement("TRUE", ldb.FLAG_MOD_REPLACE, "showInAdvancedViewOnly")
        if "objectCategory" not in obj:
            nmsg["objectCategory"] = ldb.MessageElement("CN=Container,%s" % self.schema_dn, ldb.FLAG_MOD_REPLACE, "objectCategory")
        if "isCriticalSystemObject" not in obj:
            nmsg["isCriticalSystemObject"] = ldb.MessageElement("TRUE", ldb.FLAG_MOD_REPLACE, "isCriticalSystemObject")
        if "isRecycled" in obj:
            nmsg["isRecycled"] = ldb.MessageElement("TRUE", ldb.FLAG_MOD_DELETE, "isRecycled")

        nmsg["isDeleted"] = ldb.MessageElement("TRUE", ldb.FLAG_MOD_REPLACE, "isDeleted")
        nmsg["systemFlags"] = ldb.MessageElement("-1946157056", ldb.FLAG_MOD_REPLACE, "systemFlags")
        nmsg["objectClass"] = ldb.MessageElement(["top", "container"], ldb.FLAG_MOD_REPLACE, "objectClass")

        if not self.confirm_all('Fix Deleted Objects container %s by restoring default attributes?'
                                % (dn), 'fix_deleted_deleted_objects'):
            self.report('Not fixing missing/incorrect attributes on %s\n' % (dn))
            return

        if self.do_modify(nmsg, ["relax:0"],
                          "Failed to fix Deleted Objects container  %s" % dn):
            self.report("Fixed Deleted Objects container '%s'\n" % (dn))

    def err_replica_locations(self, obj, cross_ref, attr):
        nmsg = ldb.Message()
        nmsg.dn = cross_ref
        target = self.samdb.get_dsServiceName()

        if self.samdb.am_rodc():
            self.report('Not fixing %s %s for the RODC' % (attr, obj.dn))
            return

        if not self.confirm_all('Add yourself to the replica locations for %s?'
                                % (obj.dn), 'fix_replica_locations'):
            self.report('Not fixing missing/incorrect attributes on %s\n' % (obj.dn))
            return

        nmsg[attr] = ldb.MessageElement(target, ldb.FLAG_MOD_ADD, attr)
        if self.do_modify(nmsg, [], "Failed to add %s for %s" % (attr, obj.dn)):
            self.report("Fixed %s for %s" % (attr, obj.dn))

    def is_fsmo_role(self, dn):
        if dn == self.samdb.domain_dn:
            return True
        if dn == self.infrastructure_dn:
            return True
        if dn == self.naming_dn:
            return True
        if dn == self.schema_dn:
            return True
        if dn == self.rid_dn:
            return True

        return False

    def calculate_instancetype(self, dn):
        instancetype = 0
        nc_root = self.samdb.get_nc_root(dn)
        if dn == nc_root:
            instancetype |= dsdb.INSTANCE_TYPE_IS_NC_HEAD
            try:
                self.samdb.search(base=dn.parent(), scope=ldb.SCOPE_BASE, attrs=[], controls=["show_recycled:1"])
            except ldb.LdbError as e4:
                (enum, estr) = e4.args
                if enum != ldb.ERR_NO_SUCH_OBJECT:
                    raise
            else:
                instancetype |= dsdb.INSTANCE_TYPE_NC_ABOVE
        if self.write_ncs is not None and str(nc_root) in [str(x) for x in self.write_ncs]:
            instancetype |= dsdb.INSTANCE_TYPE_WRITE

        return instancetype

    def get_wellknown_sd(self, dn):
        for [sd_dn, descriptor_fn] in self.wellknown_sds:
            if dn == sd_dn:
                domain_sid = security.dom_sid(self.samdb.get_domain_sid())
                return ndr_unpack(security.descriptor,
                                  descriptor_fn(domain_sid,
                                                name_map=self.name_map))

        raise KeyError

    def find_checkable_attrs(self, dn, requested_attrs):
        """A helper function for check_object() that calculates the list of
        attributes that need to be checked, and returns that as a list
        in the original case, and a set normalised to lowercase (for
        easy existence checks).
        """
        if requested_attrs is None:
            attrs = ['*']
        else:
            attrs = list(requested_attrs)

        lc_attrs = set(x.lower() for x in attrs)

        def add_attr(a):
            if a.lower() not in lc_attrs:
                attrs.append(a)
                lc_attrs.add(a.lower())

        if ("dn" in lc_attrs or
            "distinguishedname" in lc_attrs or
            dn.get_rdn_name().lower() in lc_attrs):
            attrs.append("name")
            lc_attrs.add('name')

        if 'name' in lc_attrs:
            for a in (dn.get_rdn_name(),
                      "isDeleted",
                      "systemFlags"):
                add_attr(a)

        need_replPropertyMetaData = False
        if '*' in lc_attrs:
            need_replPropertyMetaData = True
        else:
            for a in attrs:
                linkID, _ = self.get_attr_linkID_and_reverse_name(a)
                if linkID == 0:
                    continue
                if linkID & 1:
                    continue
                need_replPropertyMetaData = True
                break
        if need_replPropertyMetaData:
            add_attr("replPropertyMetaData")

        add_attr("objectGUID")

        return attrs, lc_attrs

    def check_object(self, dn, requested_attrs=None):
        '''check one object'''
        if self.verbose:
            self.report("Checking object %s" % dn)

        # search attrs are used to find the attributes, lc_attrs are
        # used for existence checks
        search_attrs, lc_attrs = self.find_checkable_attrs(dn, requested_attrs)

        try:
            sd_flags = 0
            sd_flags |= security.SECINFO_OWNER
            sd_flags |= security.SECINFO_GROUP
            sd_flags |= security.SECINFO_DACL
            sd_flags |= security.SECINFO_SACL

            res = self.samdb.search(base=dn, scope=ldb.SCOPE_BASE,
                                    controls=[
                                        "extended_dn:1:1",
                                        "show_recycled:1",
                                        "show_deleted:1",
                                        "sd_flags:1:%d" % sd_flags,
                                        "reveal_internals:0",
                                    ],
                                    attrs=search_attrs)
        except ldb.LdbError as e10:
            (enum, estr) = e10.args
            if enum == ldb.ERR_NO_SUCH_OBJECT:
                if self.in_transaction:
                    self.report("ERROR: Object %s disappeared during check" % dn)
                    return 1
                return 0
            raise
        if len(res) != 1:
            self.report("ERROR: Object %s failed to load during check" % dn)
            return 1
        obj = res[0]
        error_count = 0
        set_attrs_from_md = set()
        set_attrs_seen = set()
        got_objectclass = False

        nc_dn = self.samdb.get_nc_root(obj.dn)
        try:
            deleted_objects_dn = self.samdb.get_wellknown_dn(nc_dn,
                                                             samba.dsdb.DS_GUID_DELETED_OBJECTS_CONTAINER)
        except KeyError:
            # We have no deleted objects DN for schema, and we check for this above for the other
            # NCs
            deleted_objects_dn = None

        object_rdn_attr = None
        object_rdn_val = None
        name_val = None
        isDeleted = False
        systemFlags = 0
        repl_meta_data_val = None

        for attrname in obj:
            if attrname.lower() == 'isdeleted':
                if str(obj[attrname][0]) != "FALSE":
                    isDeleted = True

            if attrname.lower() == 'systemflags':
                systemFlags = int(obj[attrname][0])

            if attrname.lower() == 'replpropertymetadata':
                repl_meta_data_val = obj[attrname][0]

        if isDeleted and repl_meta_data_val:
            if self.has_changes_after_deletion(dn, repl_meta_data_val):
                error_count += 1
                self.err_changes_after_deletion(dn, repl_meta_data_val)
                return error_count
            if self.is_expired_tombstone(dn, repl_meta_data_val):
                return error_count

        for attrname in obj:
            if attrname == 'dn' or attrname == "distinguishedName":
                continue

            if attrname.lower() == 'objectclass':
                got_objectclass = True

            if attrname.lower() == "name":
                if len(obj[attrname]) != 1:
                    self.unfixable_errors += 1
                    self.report("ERROR: Not fixing num_values(%d) for '%s' on '%s'" %
                                (len(obj[attrname]), attrname, str(obj.dn)))
                else:
                    name_val = str(obj[attrname][0])

            if attrname.lower() == str(obj.dn.get_rdn_name()).lower():
                object_rdn_attr = attrname
                if len(obj[attrname]) != 1:
                    self.unfixable_errors += 1
                    self.report("ERROR: Not fixing num_values(%d) for '%s' on '%s'" %
                                (len(obj[attrname]), attrname, str(obj.dn)))
                else:
                    object_rdn_val = str(obj[attrname][0])

            if attrname.lower() == 'replpropertymetadata':
                if self.has_replmetadata_zero_invocationid(dn, obj[attrname][0]):
                    error_count += 1
                    self.err_replmetadata_zero_invocationid(dn, attrname, obj[attrname][0])
                    # We don't continue, as we may also have other fixes for this attribute
                    # based on what other attributes we see.

                try:
                    (set_attrs_from_md, list_attid_from_md, wrong_attids) \
                        = self.process_metadata(dn, obj[attrname][0])
                except KeyError:
                    error_count += 1
                    self.err_replmetadata_unknown_attid(dn, attrname, obj[attrname])
                    continue

                if len(set_attrs_from_md) < len(list_attid_from_md) \
                   or len(wrong_attids) > 0 \
                   or sorted(list_attid_from_md) != list_attid_from_md:
                    error_count += 1
                    self.err_replmetadata_incorrect_attid(dn, attrname, obj[attrname][0], wrong_attids)

                else:
                    # Here we check that the first attid is 0
                    # (objectClass).
                    if list_attid_from_md[0] != 0:
                        self.unfixable_errors += 1
                        self.report("ERROR: Not fixing incorrect initial attributeID in '%s' on '%s', it should be objectClass" %
                                    (attrname, str(dn)))

                continue

            if attrname.lower() == 'ntsecuritydescriptor':
                (sd, sd_broken) = self.process_sd(dn, obj)
                if sd_broken is not None:
                    self.err_wrong_sd(dn, sd, sd_broken)
                    error_count += 1
                    continue

                if sd.owner_sid is None or sd.group_sid is None:
                    self.err_missing_sd_owner(dn, sd)
                    error_count += 1
                    continue

                if self.reset_well_known_acls:
                    try:
                        well_known_sd = self.get_wellknown_sd(dn)
                    except KeyError:
                        continue

                    current_sd = ndr_unpack(security.descriptor,
                                            obj[attrname][0])

                    diff = get_diff_sds(well_known_sd, current_sd, security.dom_sid(self.samdb.get_domain_sid()))
                    if diff != "":
                        self.err_wrong_default_sd(dn, well_known_sd, diff)
                        error_count += 1
                        continue
                continue

            if attrname.lower() == 'objectclass':
                normalised = self.samdb.dsdb_normalise_attributes(self.samdb_schema, attrname, obj[attrname])
                # Do not consider the attribute incorrect if:
                #  - The sorted (alphabetically) list is the same, inclding case
                #  - The first and last elements are the same
                #
                # This avoids triggering an error due to
                # non-determinism in the sort routine in (at least)
                # 4.3 and earlier, and the fact that any AUX classes
                # in these attributes are also not sorted when
                # imported from Windows (they are just in the reverse
                # order of last set)
                if sorted(normalised) != sorted(obj[attrname]) \
                   or normalised[0] != obj[attrname][0] \
                   or normalised[-1] != obj[attrname][-1]:
                    self.err_normalise_mismatch_replace(dn, attrname, list(obj[attrname]))
                    error_count += 1
                continue

            if attrname.lower() == 'userparameters':
                userparams = obj[attrname][0]
                if userparams == b' ':
                    error_count += 1
                    self.err_short_userParameters(obj, attrname, obj[attrname])
                    continue

                elif userparams[:16] == b'\x20\x00' * 8:
                    # This is the correct, normal prefix
                    continue

                elif userparams[:20] == b'IAAgACAAIAAgACAAIAAg':
                    # this is the typical prefix from a windows migration
                    error_count += 1
                    self.err_base64_userParameters(obj, attrname, obj[attrname])
                    continue

                #43:00:00:00:74:00:00:00:78
                elif (userparams[1] != 0 and
                      userparams[3] != 0 and
                      userparams[5] != 0 and
                      userparams[7] != 0 and
                      userparams[9] != 0):
                    # This is a prefix that is not in UTF-16 format
                    # for the space or munged dialback prefix
                    error_count += 1
                    self.err_utf8_userParameters(obj, attrname, obj[attrname])
                    continue

                elif len(userparams) % 2 != 0:
                    # This is a value that isn't even in length
                    error_count += 1
                    self.err_odd_userParameters(obj, attrname)
                    continue

                elif (userparams[1] == 0 and
                      userparams[2] == 0 and
                      userparams[3] == 0 and
                      userparams[4] != 0 and
                      userparams[5] == 0):
                    # This is a prefix that would happen if a
                    # SAMR-written value was replicated from a Samba
                    # 4.1 server to a working server
                    error_count += 1
                    self.err_doubled_userParameters(obj, attrname, obj[attrname])
                    continue

            if attrname.lower() == 'attributeid' or attrname.lower() == 'governsid':
                if obj[attrname][0] in self.attribute_or_class_ids:
                    self.unfixable_errors += 1
                    self.report('Error: %s %s on %s already exists as an attributeId or governsId'
                                % (attrname, obj.dn, obj[attrname][0]))
                else:
                    self.attribute_or_class_ids.add(obj[attrname][0])

            # check for empty attributes
            for val in obj[attrname]:
                if val == b'':
                    self.err_empty_attribute(dn, attrname)
                    error_count += 1
                    continue

            # get the syntax oid for the attribute, so we can can have
            # special handling for some specific attribute types
            try:
                syntax_oid = self.samdb_schema.get_syntax_oid_from_lDAPDisplayName(attrname)
            except Exception as msg:
                self.err_unknown_attribute(obj, attrname)
                error_count += 1
                continue

            linkID, reverse_link_name = self.get_attr_linkID_and_reverse_name(attrname)

            flag = self.samdb_schema.get_systemFlags_from_lDAPDisplayName(attrname)
            if (not flag & dsdb.DS_FLAG_ATTR_NOT_REPLICATED
                and not flag & dsdb.DS_FLAG_ATTR_IS_CONSTRUCTED
                and not linkID):
                set_attrs_seen.add(attrname.lower())

            if syntax_oid in [dsdb.DSDB_SYNTAX_BINARY_DN, dsdb.DSDB_SYNTAX_OR_NAME,
                              dsdb.DSDB_SYNTAX_STRING_DN, ldb.SYNTAX_DN]:
                # it's some form of DN, do specialised checking on those
                error_count += self.check_dn(obj, attrname, syntax_oid)
            else:

                values = set()
                # check for incorrectly normalised attributes
                for val in obj[attrname]:
                    values.add(val)

                    normalised = self.samdb.dsdb_normalise_attributes(self.samdb_schema, attrname, [val])
                    if len(normalised) != 1 or normalised[0] != val:
                        self.err_normalise_mismatch(dn, attrname, obj[attrname])
                        error_count += 1
                        break

                if len(obj[attrname]) != len(values):
                    self.err_duplicate_values(dn, attrname, obj[attrname], list(values))
                    error_count += 1
                    break

            if attrname.lower() == "instancetype":
                calculated_instancetype = self.calculate_instancetype(dn)
                if len(obj["instanceType"]) != 1 or int(obj["instanceType"][0]) != calculated_instancetype:
                    error_count += 1
                    self.err_wrong_instancetype(obj, calculated_instancetype)

        if not got_objectclass and ("*" in lc_attrs or "objectclass" in lc_attrs):
            error_count += 1
            self.err_missing_objectclass(dn)

        if ("*" in lc_attrs or "name" in lc_attrs):
            if name_val is None:
                self.unfixable_errors += 1
                self.report("ERROR: Not fixing missing 'name' on '%s'" % (str(obj.dn)))
            if object_rdn_attr is None:
                self.unfixable_errors += 1
                self.report("ERROR: Not fixing missing '%s' on '%s'" % (obj.dn.get_rdn_name(), str(obj.dn)))

        if name_val is not None:
            parent_dn = None
            controls = ["show_recycled:1", "relax:0"]
            if isDeleted:
                if not (systemFlags & samba.dsdb.SYSTEM_FLAG_DISALLOW_MOVE_ON_DELETE):
                    parent_dn = deleted_objects_dn
                controls += ["local_oid:%s:1" % dsdb.DSDB_CONTROL_DBCHECK_FIX_LINK_DN_NAME]
            if parent_dn is None:
                parent_dn = obj.dn.parent()

            try:
                expected_dn = ldb.Dn(self.samdb, "RDN=RDN,%s" % (parent_dn))
            except ValueError as e:
                self.unfixable_errors += 1
                self.report(f"ERROR: could not handle parent DN '{parent_dn}': "
                            "skipping RDN checks")
            else:
                expected_dn.set_component(0, obj.dn.get_rdn_name(), name_val)

                if obj.dn == deleted_objects_dn:
                    expected_dn = obj.dn

                if expected_dn != obj.dn:
                    error_count += 1
                    self.err_wrong_dn(obj, expected_dn, object_rdn_attr,
                            object_rdn_val, name_val, controls)
                elif obj.dn.get_rdn_value() != object_rdn_val:
                    self.unfixable_errors += 1
                    self.report("ERROR: Not fixing %s=%r on '%s'" % (object_rdn_attr,
                                                                     object_rdn_val,
                                                                     obj.dn))

        show_dn = True
        if repl_meta_data_val:
            if obj.dn == deleted_objects_dn:
                isDeletedAttId = 131120
                # It's 29/12/9999 at 23:59:59 UTC as specified in MS-ADTS 7.1.1.4.2 Deleted Objects Container

                expectedTimeDo = 2650466015990000000
                originating = self.get_originating_time(repl_meta_data_val, isDeletedAttId)
                if originating != expectedTimeDo:
                    if self.confirm_all("Fix isDeleted originating_change_time on '%s'" % str(dn), 'fix_time_metadata'):
                        nmsg = ldb.Message()
                        nmsg.dn = dn
                        nmsg["isDeleted"] = ldb.MessageElement("TRUE", ldb.FLAG_MOD_REPLACE, "isDeleted")
                        error_count += 1
                        self.samdb.modify(nmsg, controls=["provision:0"])

                    else:
                        self.report("Not fixing isDeleted originating_change_time on '%s'" % str(dn))

            for att in set_attrs_seen.difference(set_attrs_from_md):
                if show_dn:
                    self.report("On object %s" % dn)
                    show_dn = False
                error_count += 1
                self.report("ERROR: Attribute %s not present in replication metadata" % att)
                if not self.confirm_all("Fix missing replPropertyMetaData element '%s'" % att, 'fix_all_metadata'):
                    self.report("Not fixing missing replPropertyMetaData element '%s'" % att)
                    continue
                self.fix_metadata(obj, att)

        if self.is_fsmo_role(dn):
            if "fSMORoleOwner" not in obj and ("*" in lc_attrs or "fsmoroleowner" in lc_attrs):
                self.err_no_fsmoRoleOwner(obj)
                error_count += 1

        try:
            if dn != self.samdb.get_root_basedn() and str(dn.parent()) not in self.dn_set:
                res = self.samdb.search(base=dn.parent(), scope=ldb.SCOPE_BASE,
                                        controls=["show_recycled:1", "show_deleted:1"])
        except ldb.LdbError as e11:
            (enum, estr) = e11.args
            if enum == ldb.ERR_NO_SUCH_OBJECT:
                if isDeleted:
                    self.report("WARNING: parent object not found for %s" % (obj.dn))
                    self.report("Not moving to LostAndFound "
                                "(tombstone garbage collection in progress?)")
                else:
                    self.err_missing_parent(obj)
                    error_count += 1
            else:
                raise

        if dn in self.deleted_objects_containers and '*' in lc_attrs:
            if self.is_deleted_deleted_objects(obj):
                self.err_deleted_deleted_objects(obj)
                error_count += 1

        for (dns_part, msg) in self.dns_partitions:
            if dn == dns_part and 'repsFrom' in obj:
                location = "msDS-NC-Replica-Locations"
                if self.samdb.am_rodc():
                    location = "msDS-NC-RO-Replica-Locations"

                if location not in msg:
                    # There are no replica locations!
                    self.err_replica_locations(obj, msg.dn, location)
                    error_count += 1
                    continue

                found = False
                for loc in msg[location]:
                    if str(loc) == self.samdb.get_dsServiceName():
                        found = True
                if not found:
                    # This DC is not in the replica locations
                    self.err_replica_locations(obj, msg.dn, location)
                    error_count += 1

        if dn == self.server_ref_dn:
            # Check we have a valid RID Set
            if "*" in lc_attrs or "ridsetreferences" in lc_attrs:
                if "rIDSetReferences" not in obj:
                    # NO RID SET reference
                    # We are RID master, allocate it.
                    error_count += 1

                    if self.is_rid_master:
                        # Allocate a RID Set
                        if self.confirm_all('Allocate the missing RID set for '
                                            'RID master?',
                                            'fix_missing_rid_set_master'):

                            # We don't have auto-transaction logic on
                            # extended operations, so we have to do it
                            # here.

                            self.samdb.transaction_start()

                            try:
                                self.samdb.create_own_rid_set()

                            except:
                                self.samdb.transaction_cancel()
                                raise

                            self.samdb.transaction_commit()

                    elif not self.samdb.am_rodc():
                        self.report("No RID Set found for this server: %s, "
                                    "and we are not the RID Master (so can "
                                    "not self-allocate)" % dn)

        # Check some details of our own RID Set
        #
        # Note that the attributes have very bad names.  From ridalloc.c:
        #
        #   Note: the RID allocation attributes in AD are very badly named.
        #     Here is what we think they really do:
        #
        #     in RID Set object:
        #       - rIDPreviousAllocationPool: the pool which a DC is currently
        #         pulling RIDs from. Managed by client DC
        #
        #       - rIDAllocationPool: the pool that the DC will switch to next,
        #         when rIDPreviousAllocationPool is exhausted. Managed by RID
        #         Manager.
        #
        #       - rIDNextRID: the last RID allocated by this DC. Managed by
        #         client DC
        #
        #     in RID Manager object:
        #       - rIDAvailablePool: the pool where the RID Manager gets new rID
        #         pools from when it gets a EXOP_RID_ALLOC getncchanges call
        #         (or locally when the DC is the RID Manager)

        if dn == self.rid_set_dn:
            pool_attrs = ["rIDAllocationPool", "rIDPreviousAllocationPool"]

            res = self.samdb.search(base=self.rid_set_dn, scope=ldb.SCOPE_BASE,
                                    attrs=pool_attrs)

            for pool_attr in pool_attrs:
                if pool_attr not in res[0]:
                    continue

                pool = int(res[0][pool_attr][0])

                high = pool >> 32
                low = 0xFFFFFFFF & pool

                if pool != 0 and low >= high:
                    self.report("Invalid RID pool %d-%d, %d >= %d!" %
                                (low, high, low, high))
                    self.unfixable_errors += 1

            if "rIDAllocationPool" not in res[0]:
                self.report("No rIDAllocationPool found in %s" % dn)
                self.unfixable_errors += 1

            try:
                next_free_rid, high = self.samdb.free_rid_bounds()
            except ldb.LdbError as err:
                enum, estr = err.args
                self.report("Couldn't get available RIDs: %s" % estr)
                self.unfixable_errors += 1
            else:
                # Check the remainder of this pool for conflicts.  If
                # ridalloc_allocate_rid() moves to a new pool, this
                # will be above high, so we will stop.
                domain_sid = self.samdb.get_domain_sid()
                while next_free_rid <= high:
                    sid = "%s-%d" % (domain_sid, next_free_rid)
                    try:
                        res = self.samdb.search(base="<SID=%s>" % sid,
                                                scope=ldb.SCOPE_BASE,
                                                attrs=[])
                    except ldb.LdbError as e:
                        (enum, estr) = e.args
                        if enum != ldb.ERR_NO_SUCH_OBJECT:
                            raise
                        res = None
                    if res is not None:
                        self.report("SID %s for %s conflicts with our current "
                                    "RID set in %s" % (sid, res[0].dn, dn))
                        error_count += 1

                        if self.confirm_all('Fix conflict between SID %s and '
                                            'RID pool in %s by allocating a '
                                            'new RID?'
                                            % (sid, dn),
                                            'fix_sid_rid_set_conflict'):
                            self.samdb.transaction_start()

                            # This will burn RIDs, which will move
                            # past the conflict.  We then check again
                            # to see if the new RID conflicts, until
                            # the end of the current pool.  We don't
                            # look at the next pool to avoid burning
                            # all RIDs in one go in some strange
                            # failure case.
                            try:
                                while True:
                                    allocated_rid = self.samdb.allocate_rid()
                                    if allocated_rid >= next_free_rid:
                                        next_free_rid = allocated_rid + 1
                                        break
                            except:
                                self.samdb.transaction_cancel()
                                raise

                            self.samdb.transaction_commit()
                        else:
                            break
                    else:
                        next_free_rid += 1

        return error_count

    ################################################################
    # check special @ROOTDSE attributes
    def check_rootdse(self):
        '''check the @ROOTDSE special object'''
        dn = ldb.Dn(self.samdb, '@ROOTDSE')
        if self.verbose:
            self.report("Checking object %s" % dn)
        res = self.samdb.search(base=dn, scope=ldb.SCOPE_BASE)
        if len(res) != 1:
            self.report("Object %s disappeared during check" % dn)
            return 1
        obj = res[0]
        error_count = 0

        # check that the dsServiceName is in GUID form
        if 'dsServiceName' not in obj:
            self.report('ERROR: dsServiceName missing in @ROOTDSE')
            return error_count + 1

        if not str(obj['dsServiceName'][0]).startswith('<GUID='):
            self.report('ERROR: dsServiceName not in GUID form in @ROOTDSE')
            error_count += 1
            if not self.confirm('Change dsServiceName to GUID form?'):
                return error_count
            res = self.samdb.search(base=ldb.Dn(self.samdb, obj['dsServiceName'][0].decode('utf8')),
                                    scope=ldb.SCOPE_BASE, attrs=['objectGUID'])
            guid_str = str(ndr_unpack(misc.GUID, res[0]['objectGUID'][0]))
            m = ldb.Message()
            m.dn = dn
            m['dsServiceName'] = ldb.MessageElement("<GUID=%s>" % guid_str,
                                                    ldb.FLAG_MOD_REPLACE, 'dsServiceName')
            if self.do_modify(m, [], "Failed to change dsServiceName to GUID form", validate=False):
                self.report("Changed dsServiceName to GUID form")
        return error_count

    ###############################################
    # re-index the database

    def reindex_database(self):
        '''re-index the whole database'''
        m = ldb.Message()
        m.dn = ldb.Dn(self.samdb, "@ATTRIBUTES")
        m['add']    = ldb.MessageElement('NONE', ldb.FLAG_MOD_ADD, 'force_reindex')
        m['delete'] = ldb.MessageElement('NONE', ldb.FLAG_MOD_DELETE, 'force_reindex')
        return self.do_modify(m, [], 're-indexed database', validate=False)

    ###############################################
    # reset @MODULES
    def reset_modules(self):
        '''reset @MODULES to that needed for current sam.ldb (to read a very old database)'''
        m = ldb.Message()
        m.dn = ldb.Dn(self.samdb, "@MODULES")
        m['@LIST'] = ldb.MessageElement('samba_dsdb', ldb.FLAG_MOD_REPLACE, '@LIST')
        return self.do_modify(m, [], 'reset @MODULES on database', validate=False)