samba-mirror/source4/scripting/python/samba/upgradehelpers.py

#!/usr/bin/env python
#
# Helpers for provision stuff
# Copyright (C) Matthieu Patou <mat@matws.net> 2009-2010
#
# Based on provision a Samba4 server by
# Copyright (C) Jelmer Vernooij <jelmer@samba.org> 2007-2008
# Copyright (C) Andrew Bartlett <abartlet@samba.org> 2008
#
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import os
import string
import re
import shutil
import samba

from samba import Ldb, version, ntacls
from samba.dsdb import DS_DOMAIN_FUNCTION_2000
from ldb import SCOPE_SUBTREE, SCOPE_ONELEVEL, SCOPE_BASE
import ldb
from samba.provision import (ProvisionNames, provision_paths_from_lp,
                            getpolicypath, set_gpo_acl, create_gpo_struct,
                            FILL_FULL, provision, ProvisioningError,
                            setsysvolacl, secretsdb_self_join)
from samba.dcerpc import misc, security, xattr
from samba.dcerpc.misc import SEC_CHAN_BDC
from samba.ndr import ndr_unpack
from samba.samdb import SamDB

# All the ldb related to registry are commented because the path for them is relative
# in the provisionPath object
# And so opening them create a file in the current directory which is not what we want
# I still keep them commented because I plan soon to make more cleaner
ERROR =     -1
SIMPLE =     0x00
CHANGE =     0x01
CHANGESD =     0x02
GUESS =     0x04
PROVISION =    0x08
CHANGEALL =    0xff

hashAttrNotCopied = {   "dn": 1, "whenCreated": 1, "whenChanged": 1,
                        "objectGUID": 1, "uSNCreated": 1,
                        "replPropertyMetaData": 1, "uSNChanged": 1,
                        "parentGUID": 1, "objectCategory": 1,
                        "distinguishedName": 1, "nTMixedDomain": 1,
                        "showInAdvancedViewOnly": 1, "instanceType": 1,
                        "msDS-Behavior-Version":1, "nextRid":1, "cn": 1,
                        "versionNumber":1, "lmPwdHistory":1, "pwdLastSet": 1,
                        "ntPwdHistory":1, "unicodePwd":1,"dBCSPwd":1,
                        "supplementalCredentials":1, "gPCUserExtensionNames":1,
                        "gPCMachineExtensionNames":1,"maxPwdAge":1, "secret":1,
                        "possibleInferiors":1, "privilege":1,
                        "sAMAccountType":1 }

class ProvisionLDB(object):

    def __init__(self):
        self.sam = None
        self.secrets = None
        self.idmap = None
        self.privilege = None
        self.hkcr = None
        self.hkcu = None
        self.hku = None
        self.hklm = None

    def startTransactions(self):
        self.sam.transaction_start()
        self.secrets.transaction_start()
        self.idmap.transaction_start()
        self.privilege.transaction_start()
# TO BE DONE
#        self.hkcr.transaction_start()
#        self.hkcu.transaction_start()
#        self.hku.transaction_start()
#        self.hklm.transaction_start()

    def groupedRollback(self):
        ok = True
        try:
            self.sam.transaction_cancel()
        except:
            ok = False

        try:
            self.secrets.transaction_cancel()
        except:
            ok = False

        try:
            self.idmap.transaction_cancel()
        except:
            ok = False

        try:
            self.privilege.transaction_cancel()
        except:
            ok = False

        return ok
# TO BE DONE
#        self.hkcr.transaction_cancel()
#        self.hkcu.transaction_cancel()
#        self.hku.transaction_cancel()
#        self.hklm.transaction_cancel()

    def groupedCommit(self):
        try:
            self.sam.transaction_prepare_commit()
            self.secrets.transaction_prepare_commit()
            self.idmap.transaction_prepare_commit()
            self.privilege.transaction_prepare_commit()
        except:
            return self.groupedRollback()
# TO BE DONE
#        self.hkcr.transaction_prepare_commit()
#        self.hkcu.transaction_prepare_commit()
#        self.hku.transaction_prepare_commit()
#        self.hklm.transaction_prepare_commit()
        try:
            self.sam.transaction_commit()
            self.secrets.transaction_commit()
            self.idmap.transaction_commit()
            self.privilege.transaction_commit()
        except:
            return self.groupedRollback()
        
# TO BE DONE
#        self.hkcr.transaction_commit()
#        self.hkcu.transaction_commit()
#        self.hku.transaction_commit()
#        self.hklm.transaction_commit()
        return True

def get_ldbs(paths, creds, session, lp):
    """Return LDB object mapped on most important databases

    :param paths: An object holding the different importants paths for provision object
    :param creds: Credential used for openning LDB files
    :param session: Session to use for openning LDB files
    :param lp: A loadparam object
    :return: A ProvisionLDB object that contains LDB object for the different LDB files of the provision"""

    ldbs = ProvisionLDB()

    ldbs.sam = SamDB(paths.samdb, session_info=session, credentials=creds, lp=lp, options=["modules:samba_dsdb"])
    ldbs.secrets = Ldb(paths.secrets, session_info=session, credentials=creds, lp=lp)
    ldbs.idmap = Ldb(paths.idmapdb, session_info=session, credentials=creds, lp=lp)
    ldbs.privilege = Ldb(paths.privilege, session_info=session, credentials=creds, lp=lp)
#    ldbs.hkcr = Ldb(paths.hkcr, session_info=session, credentials=creds, lp=lp)
#    ldbs.hkcu = Ldb(paths.hkcu, session_info=session, credentials=creds, lp=lp)
#    ldbs.hku = Ldb(paths.hku, session_info=session, credentials=creds, lp=lp)
#    ldbs.hklm = Ldb(paths.hklm, session_info=session, credentials=creds, lp=lp)

    return ldbs


def usn_in_range(usn, range):
    """Check if the usn is in one of the range provided.
    To do so, the value is checked to be between the lower bound and
    higher bound of a range

    :param usn: A integer value corresponding to the usn that we want to update
    :param range: A list of integer representing ranges, lower bounds are in
                  the even indices, higher in odd indices
    :return: True if the usn is in one of the range, False otherwise
    """

    idx = 0
    cont = True
    ok = False
    while cont:
        if idx ==  len(range):
            cont = False
            continue
        if usn < int(range[idx]):
            if idx %2 == 1:
                ok = True
            cont = False
        if usn == int(range[idx]):
            cont = False
            ok = True
        idx = idx + 1
    return ok


def get_paths(param, targetdir=None, smbconf=None):
    """Get paths to important provision objects (smb.conf, ldb files, ...)

    :param param: Param object
    :param targetdir: Directory where the provision is (or will be) stored
    :param smbconf: Path to the smb.conf file
    :return: A list with the path of important provision objects"""
    if targetdir is not None:
        etcdir = os.path.join(targetdir, "etc")
        if not os.path.exists(etcdir):
            os.makedirs(etcdir)
        smbconf = os.path.join(etcdir, "smb.conf")
    if smbconf is None:
        smbconf = param.default_path()

    if not os.path.exists(smbconf):
        raise ProvisioningError("Unable to find smb.conf")

    lp = param.LoadParm()
    lp.load(smbconf)
    paths = provision_paths_from_lp(lp, lp.get("realm"))
    return paths

def update_policyids(names, samdb):
    """Update policy ids that could have changed after sam update

    :param names: List of key provision parameters
    :param samdb: An Ldb object conntected with the sam DB
    """
    # policy guid
    res = samdb.search(expression="(displayName=Default Domain Policy)",
                        base="CN=Policies,CN=System," + str(names.rootdn),
                        scope=SCOPE_ONELEVEL, attrs=["cn","displayName"])
    names.policyid = str(res[0]["cn"]).replace("{","").replace("}","")
    # dc policy guid
    res2 = samdb.search(expression="(displayName=Default Domain Controllers" \
                                   " Policy)",
                            base="CN=Policies,CN=System," + str(names.rootdn),
                            scope=SCOPE_ONELEVEL, attrs=["cn","displayName"])
    if len(res2) == 1:
        names.policyid_dc = str(res2[0]["cn"]).replace("{","").replace("}","")
    else:
        names.policyid_dc = None


def find_provision_key_parameters(samdb, secretsdb, idmapdb, paths, smbconf, lp):
    """Get key provision parameters (realm, domain, ...) from a given provision

    :param samdb: An LDB object connected to the sam.ldb file
    :param secretsdb: An LDB object connected to the secrets.ldb file
    :param idmapdb: An LDB object connected to the idmap.ldb file
    :param paths: A list of path to provision object
    :param smbconf: Path to the smb.conf file
    :param lp: A LoadParm object
    :return: A list of key provision parameters
    """
    names = ProvisionNames()
    names.adminpass = None

    # NT domain, kerberos realm, root dn, domain dn, domain dns name
    names.domain = string.upper(lp.get("workgroup"))
    names.realm = lp.get("realm")
    basedn = "DC=" + names.realm.replace(".",",DC=")
    names.dnsdomain = names.realm.lower()
    names.realm = string.upper(names.realm)
    # netbiosname
    # Get the netbiosname first (could be obtained from smb.conf in theory)
    res = secretsdb.search(expression="(flatname=%s)" % \
                            names.domain,base="CN=Primary Domains",
                            scope=SCOPE_SUBTREE, attrs=["sAMAccountName"])
    names.netbiosname = str(res[0]["sAMAccountName"]).replace("$","")

    names.smbconf = smbconf

    # That's a bit simplistic but it's ok as long as we have only 3
    # partitions
    current = samdb.search(expression="(objectClass=*)", 
        base="", scope=SCOPE_BASE,
        attrs=["defaultNamingContext", "schemaNamingContext",
               "configurationNamingContext","rootDomainNamingContext"])

    names.configdn = current[0]["configurationNamingContext"]
    configdn = str(names.configdn)
    names.schemadn = current[0]["schemaNamingContext"]
    if not (ldb.Dn(samdb, basedn) == (ldb.Dn(samdb,
                                       current[0]["defaultNamingContext"][0]))):
        raise ProvisioningError(("basedn in %s (%s) and from %s (%s)"
                                 "is not the same ..." % (paths.samdb,
                                    str(current[0]["defaultNamingContext"][0]),
                                    paths.smbconf, basedn)))

    names.domaindn=current[0]["defaultNamingContext"]
    names.rootdn=current[0]["rootDomainNamingContext"]
    # default site name
    res3 = samdb.search(expression="(objectClass=*)", 
        base="CN=Sites," + configdn, scope=SCOPE_ONELEVEL, attrs=["cn"])
    names.sitename = str(res3[0]["cn"])

    # dns hostname and server dn
    res4 = samdb.search(expression="(CN=%s)" % names.netbiosname,
                            base="OU=Domain Controllers,%s" % basedn,
                            scope=SCOPE_ONELEVEL, attrs=["dNSHostName"])
    names.hostname = str(res4[0]["dNSHostName"]).replace("." + names.dnsdomain,"")

    server_res = samdb.search(expression="serverReference=%s" % res4[0].dn,
                                attrs=[], base=configdn)
    names.serverdn = server_res[0].dn

    # invocation id/objectguid
    res5 = samdb.search(expression="(objectClass=*)",
            base="CN=NTDS Settings,%s" % str(names.serverdn), scope=SCOPE_BASE,
            attrs=["invocationID", "objectGUID"])
    names.invocation = str(ndr_unpack(misc.GUID, res5[0]["invocationId"][0]))
    names.ntdsguid = str(ndr_unpack(misc.GUID, res5[0]["objectGUID"][0]))

    # domain guid/sid
    res6 = samdb.search(expression="(objectClass=*)", base=basedn,
            scope=SCOPE_BASE, attrs=["objectGUID",
                "objectSid","msDS-Behavior-Version" ])
    names.domainguid = str(ndr_unpack(misc.GUID, res6[0]["objectGUID"][0]))
    names.domainsid = ndr_unpack( security.dom_sid, res6[0]["objectSid"][0])
    if res6[0].get("msDS-Behavior-Version") is None or \
        int(res6[0]["msDS-Behavior-Version"][0]) < DS_DOMAIN_FUNCTION_2000:
        names.domainlevel = DS_DOMAIN_FUNCTION_2000
    else:
        names.domainlevel = int(res6[0]["msDS-Behavior-Version"][0])

    # policy guid
    res7 = samdb.search(expression="(displayName=Default Domain Policy)",
                        base="CN=Policies,CN=System," + basedn,
                        scope=SCOPE_ONELEVEL, attrs=["cn","displayName"])
    names.policyid = str(res7[0]["cn"]).replace("{","").replace("}","")
    # dc policy guid
    res8 = samdb.search(expression="(displayName=Default Domain Controllers" \
                                   " Policy)",
                            base="CN=Policies,CN=System," + basedn,
                            scope=SCOPE_ONELEVEL, attrs=["cn","displayName"])
    if len(res8) == 1:
        names.policyid_dc = str(res8[0]["cn"]).replace("{","").replace("}","")
    else:
        names.policyid_dc = None
    res9 = idmapdb.search(expression="(cn=%s)" % \
                            (security.SID_BUILTIN_ADMINISTRATORS),
                            attrs=["xidNumber"])
    if len(res9) == 1:
        names.wheel_gid = res9[0]["xidNumber"]
    else:
        raise ProvisioningError("Unable to find uid/gid for Domain Admins rid")
    return names


def newprovision(names, setup_dir, creds, session, smbconf, provdir, logger):
    """Create a new provision.

    This provision will be the reference for knowing what has changed in the
    since the latest upgrade in the current provision

    :param names: List of provision parameters
    :param setup_dis: Directory where the setup files are stored
    :param creds: Credentials for the authentification
    :param session: Session object
    :param smbconf: Path to the smb.conf file
    :param provdir: Directory where the provision will be stored
    :param logger: A `Logger`
    """
    if os.path.isdir(provdir):
        shutil.rmtree(provdir)
    os.chdir(os.path.join(setup_dir,".."))
    os.mkdir(provdir)
    logger.info("Provision stored in %s", provdir)
    provision(setup_dir, logger, session, creds, smbconf=smbconf,
            targetdir=provdir, samdb_fill=FILL_FULL, realm=names.realm,
            domain=names.domain, domainguid=names.domainguid,
            domainsid=str(names.domainsid), ntdsguid=names.ntdsguid,
            policyguid=names.policyid, policyguid_dc=names.policyid_dc,
            hostname=names.netbiosname, hostip=None, hostip6=None,
            invocationid=names.invocation, adminpass=names.adminpass,
            krbtgtpass=None, machinepass=None, dnspass=None, root=None,
            nobody=None, wheel=None, users=None,
            serverrole="domain controller", ldap_backend_extra_port=None,
            backend_type=None, ldapadminpass=None, ol_mmr_urls=None,
            slapd_path=None, setup_ds_path=None, nosync=None,
            dom_for_fun_level=names.domainlevel,
            ldap_dryrun_mode=None, useeadb=True)


def dn_sort(x, y):
    """Sorts two DNs in the lexicographical order it and put higher level DN
    before.

    So given the dns cn=bar,cn=foo and cn=foo the later will be return as
    smaller

    :param x: First object to compare
    :param y: Second object to compare
    """
    p = re.compile(r'(?<!\\), ?')
    tab1 = p.split(str(x))
    tab2 = p.split(str(y))
    minimum = min(len(tab1), len(tab2))
    len1 = len(tab1)-1
    len2 = len(tab2)-1
    # Note: python range go up to upper limit but do not include it
    for i in range(0, minimum):
        ret = cmp(tab1[len1-i], tab2[len2-i])
        if ret != 0:
            return ret
        else:
            if i == minimum-1:
                assert len1!=len2,"PB PB PB" + " ".join(tab1)+" / " + " ".join(tab2)
                if len1 > len2:
                    return 1
                else:
                    return -1
    return ret


def identic_rename(ldbobj, dn):
    """Perform a back and forth rename to trigger renaming on attribute that
    can't be directly modified.

    :param lbdobj: An Ldb Object
    :param dn: DN of the object to manipulate
    """
    (before, after) = str(dn).split('=', 1)
    ldbobj.rename(dn, ldb.Dn(ldbobj, "%s=foo%s" % (before, after)))
    ldbobj.rename(ldb.Dn(ldbobj, "%s=foo%s" % (before, after)), dn)


def chunck_acl(acl):
    """Return separate ACE of an ACL

    :param acl: A string representing the ACL
    :return: A hash with different parts
    """

    p = re.compile(r'(\w+)?(\(.*?\))')
    tab = p.findall(acl)

    hash = {}
    hash["aces"] = []
    for e in tab:
        if len(e[0]) > 0:
            hash["flags"] = e[0]
        hash["aces"].append(e[1])

    return hash


def chunck_sddl(sddl):
    """ Return separate parts of the SDDL (owner, group, ...)

    :param sddl: An string containing the SDDL to chunk
    :return: A hash with the different chunk
    """

    p = re.compile(r'([OGDS]:)(.*?)(?=(?:[GDS]:|$))')
    tab = p.findall(sddl)

    hash = {}
    for e in tab:
        if e[0] == "O:":
            hash["owner"] = e[1]
        if e[0] == "G:":
            hash["group"] = e[1]
        if e[0] == "D:":
            hash["dacl"] = e[1]
        if e[0] == "S:":
            hash["sacl"] = e[1]

    return hash

def get_diff_sddls(refsddl, cursddl):
    """Get the difference between 2 sddl
       This function split the textual representation of ACL into smaller
       chunck in order to not to report a simple permutation as a difference

       :param refsddl: First sddl to compare
       :param cursddl: Second sddl to compare
       :return: A string that explain difference between sddls"""

    txt = ""
    hash_new = chunck_sddl(cursddl)
    hash_ref = chunck_sddl(refsddl)

    if hash_new["owner"] != hash_ref["owner"]:
        txt = "\tOwner mismatch: %s (in ref) %s" \
              "(in current)\n" % (hash_ref["owner"], hash_new["owner"])

    if hash_new["group"] != hash_ref["group"]:
        txt = "%s\tGroup mismatch: %s (in ref) %s" \
              "(in current)\n" % (txt, hash_ref["group"], hash_new["group"])

    for part in ["dacl", "sacl"]:
        if hash_new.has_key(part) and hash_ref.has_key(part):

            # both are present, check if they contain the same ACE
            h_new = set()
            h_ref = set()
            c_new = chunck_acl(hash_new[part])
            c_ref = chunck_acl(hash_ref[part])

            for elem in c_new["aces"]:
                h_new.add(elem)

            for elem in c_ref["aces"]:
                h_ref.add(elem)

            for k in set(h_ref):
                if k in h_new:
                    h_new.remove(k)
                    h_ref.remove(k)

            if len(h_new) + len(h_ref) > 0:
                txt = "%s\tPart %s is different between reference" \
                      " and current here is the detail:\n" % (txt, part)

                for item in h_new:
                    txt = "%s\t\t%s ACE is not present in the" \
                          " reference\n" % (txt, item)

                for item in h_ref:
                    txt = "%s\t\t%s ACE is not present in the" \
                          " current\n" % (txt, item)

        elif hash_new.has_key(part) and not hash_ref.has_key(part):
            txt = "%s\tReference ACL hasn't a %s part\n" % (txt, part)
        elif not hash_new.has_key(part) and hash_ref.has_key(part):
            txt = "%s\tCurrent ACL hasn't a %s part\n" % (txt, part)

    return txt


def update_secrets(newsecrets_ldb, secrets_ldb, messagefunc):
    """Update secrets.ldb

    :param newsecrets_ldb: An LDB object that is connected to the secrets.ldb
                            of the reference provision
    :param secrets_ldb: An LDB object that is connected to the secrets.ldb
                            of the updated provision
    """

    messagefunc(SIMPLE, "update secrets.ldb")
    reference = newsecrets_ldb.search(expression="dn=@MODULES", base="",
                                        scope=SCOPE_SUBTREE)
    current = secrets_ldb.search(expression="dn=@MODULES", base="",
                                        scope=SCOPE_SUBTREE)
    assert reference, "Reference modules list can not be empty"
    if len(current) == 0:
        # No modules present
        delta = secrets_ldb.msg_diff(ldb.Message(), reference[0])
        delta.dn = reference[0].dn
        secrets_ldb.add(reference[0])
    else:
        delta = secrets_ldb.msg_diff(current[0], reference[0])
        delta.dn = current[0].dn
        secrets_ldb.modify(delta)

    reference = newsecrets_ldb.search(expression="objectClass=top", base="",
                                        scope=SCOPE_SUBTREE, attrs=["dn"])
    current = secrets_ldb.search(expression="objectClass=top", base="",
                                        scope=SCOPE_SUBTREE, attrs=["dn"])
    hash_new = {}
    hash = {}
    listMissing = []
    listPresent = []

    empty = ldb.Message()
    for i in range(0, len(reference)):
        hash_new[str(reference[i]["dn"]).lower()] = reference[i]["dn"]

    # Create a hash for speeding the search of existing object in the
    # current provision
    for i in range(0, len(current)):
        hash[str(current[i]["dn"]).lower()] = current[i]["dn"]

    for k in hash_new.keys():
        if not hash.has_key(k):
            listMissing.append(hash_new[k])
        else:
            listPresent.append(hash_new[k])

    for entry in listMissing:
        reference = newsecrets_ldb.search(expression="dn=%s" % entry,
                                            base="", scope=SCOPE_SUBTREE)
        current = secrets_ldb.search(expression="dn=%s" % entry,
                                            base="", scope=SCOPE_SUBTREE)
        delta = secrets_ldb.msg_diff(empty, reference[0])
        for att in hashAttrNotCopied.keys():
            delta.remove(att)
        messagefunc(CHANGE, "Entry %s is missing from secrets.ldb" % \
                    reference[0].dn)
        for att in delta:
            messagefunc(CHANGE, " Adding attribute %s" % att)
        delta.dn = reference[0].dn
        secrets_ldb.add(delta)

    for entry in listPresent:
        reference = newsecrets_ldb.search(expression="dn=%s" % entry,
                                            base="", scope=SCOPE_SUBTREE)
        current = secrets_ldb.search(expression="dn=%s" % entry, base="",
                                            scope=SCOPE_SUBTREE)
        delta = secrets_ldb.msg_diff(current[0], reference[0])
        for att in hashAttrNotCopied.keys():
            delta.remove(att)
        for att in delta:
            if att == "name":
                messagefunc(CHANGE, "Found attribute name on  %s," \
                                    " must rename the DN" % (current[0].dn))
                identic_rename(secrets_ldb, reference[0].dn)
            else:
                delta.remove(att)

    for entry in listPresent:
        reference = newsecrets_ldb.search(expression="dn=%s" % entry, base="",
                                            scope=SCOPE_SUBTREE)
        current = secrets_ldb.search(expression="dn=%s" % entry, base="",
                                            scope=SCOPE_SUBTREE)
        delta = secrets_ldb.msg_diff(current[0], reference[0])
        for att in hashAttrNotCopied.keys():
            delta.remove(att)
        for att in delta:
            if att == "msDS-KeyVersionNumber":
                delta.remove(att)
            if att != "dn":
                messagefunc(CHANGE,
                            "Adding/Changing attribute %s to %s" % \
                            (att, current[0].dn))

        delta.dn = current[0].dn
        secrets_ldb.modify(delta)

def getOEMInfo(samdb, rootdn):
    """Return OEM Information on the top level
    Samba4 use to store version info in this field

    :param samdb: An LDB object connect to sam.ldb
    :param rootdn: Root DN of the domain
    :return: The content of the field oEMInformation (if any)"""
    res = samdb.search(expression="(objectClass=*)", base=str(rootdn),
                            scope=SCOPE_BASE, attrs=["dn", "oEMInformation"])
    if len(res) > 0:
        info = res[0]["oEMInformation"]
        return info
    else:
        return ""

def updateOEMInfo(samdb, rootdn):
    """Update the OEMinfo field to add information about upgrade
       :param samdb: an LDB object connected to the sam DB
       :param rootdn: The string representation of the root DN of
                      the provision (ie. DC=...,DC=...)
    """
    res = samdb.search(expression="(objectClass=*)", base=rootdn,
                            scope=SCOPE_BASE, attrs=["dn", "oEMInformation"])
    if len(res) > 0:
        info = res[0]["oEMInformation"]
        info = "%s, upgrade to %s" % (info, version)
        delta = ldb.Message()
        delta.dn = ldb.Dn(samdb, str(res[0]["dn"]))
        delta["oEMInformation"] = ldb.MessageElement(info, ldb.FLAG_MOD_REPLACE,
                                                        "oEMInformation" )
        samdb.modify(delta)

def update_gpo(paths, samdb, names, lp, message, force=0):
    """Create missing GPO file object if needed

    Set ACL correctly also.
    Check ACLs for sysvol/netlogon dirs also
    """
    resetacls = False
    try:
        ntacls.checkset_backend(lp, None, None)
        eadbname = lp.get("posix:eadb")
        if eadbname is not None and eadbname != "":
            try:
                attribute = samba.xattr_tdb.wrap_getxattr(eadbname,
                                paths.sysvol, xattr.XATTR_NTACL_NAME)
            except:
                attribute = samba.xattr_native.wrap_getxattr(paths.sysvol,
                                xattr.XATTR_NTACL_NAME)
        else:
            attribute = samba.xattr_native.wrap_getxattr(paths.sysvol,
                                xattr.XATTR_NTACL_NAME)
    except:
       resetacls = True

    if force:
        resetacls = True

    dir = getpolicypath(paths.sysvol, names.dnsdomain, names.policyid)
    if not os.path.isdir(dir):
        create_gpo_struct(dir)

    if names.policyid_dc is None:
        raise ProvisioningError("Policy ID for Domain controller is missing")
    dir = getpolicypath(paths.sysvol, names.dnsdomain, names.policyid_dc)
    if not os.path.isdir(dir):
        create_gpo_struct(dir)
    # We always reinforce acls on GPO folder because they have to be in sync
    # with the one in DS
    try:
        set_gpo_acl(paths.sysvol, names.dnsdomain, names.domainsid,
            names.domaindn, samdb, lp)
    except TypeError, e:
        message(ERROR, "Unable to set ACLs on policies related objects,"
                       " if not using posix:eadb, you must be root to do it")

    if resetacls:
       try:
            setsysvolacl(samdb, paths.netlogon, paths.sysvol, names.wheel_gid,
                        names.domainsid, names.dnsdomain, names.domaindn, lp)
       except TypeError, e:
            message(ERROR, "Unable to set ACLs on sysvol share, if not using"
                           "posix:eadb, you must be root to do it")

def increment_calculated_keyversion_number(samdb, rootdn, hashDns):
    """For a given hash associating dn and a number, this function will
    update the replPropertyMetaData of each dn in the hash, so that the
    calculated value of the msDs-KeyVersionNumber is equal or superior to the
    one associated to the given dn.

    :param samdb: An SamDB object pointing to the sam
    :param rootdn: The base DN where we want to start
    :param hashDns: A hash with dn as key and number representing the
                 minimum value of msDs-KeyVersionNumber that we want to
                 have
    """
    entry = samdb.search(expression='(objectClass=user)',
                         base=ldb.Dn(samdb,str(rootdn)),
                         scope=SCOPE_SUBTREE, attrs=["msDs-KeyVersionNumber"],
                         controls=["search_options:1:2"])
    done = 0
    if len(entry) == 0:
        raise ProvisioningError("Unable to find msDs-KeyVersionNumber")
    else:
        for e in entry:
            if hashDns.has_key(str(e.dn).lower()):
                done = done + 1
                val = e.get("msDs-KeyVersionNumber")
                if not val:
                    continue
                version = int(str(hashDns[str(e.dn).lower()]))
                if int(str(val)) < version:
                    samdb.set_attribute_replmetadata_version(str(e.dn),
                                                              "unicodePwd",
                                                              version)

def delta_update_basesamdb(refsam, sam, creds, session, lp, message):
    """Update the provision container db: sam.ldb
    This function is aimed for alpha9 and newer;

    :param refsam: Path to the samdb in the reference provision
    :param sam: Path to the samdb in the upgraded provision
    :param creds: Credential used for openning LDB files
    :param session: Session to use for openning LDB files
    :param lp: A loadparam object"""

    message(SIMPLE,
            "Update base samdb by searching difference with reference one")
    refsam = Ldb(refsam, session_info=session, credentials=creds,
                    lp=lp, options=["modules:"])
    sam = Ldb(sam, session_info=session, credentials=creds, lp=lp,
                options=["modules:"])

    empty = ldb.Message()

    reference = refsam.search(expression="")

    for refentry in reference:
        entry = sam.search(expression="dn=%s" % refentry["dn"],
                            scope=SCOPE_SUBTREE)
        if not len(entry):
            delta = sam.msg_diff(empty, refentry)
            message(CHANGE, "Adding %s to sam db" % str(refentry.dn))
            if str(refentry.dn) == "@PROVISION" and\
                delta.get(samba.provision.LAST_PROVISION_USN_ATTRIBUTE):
                delta.remove(samba.provision.LAST_PROVISION_USN_ATTRIBUTE)
            delta.dn = refentry.dn
            sam.add(delta)
        else:
            delta = sam.msg_diff(entry[0], refentry)
            if str(refentry.dn) == "@PROVISION" and\
                delta.get(samba.provision.LAST_PROVISION_USN_ATTRIBUTE):
                delta.remove(samba.provision.LAST_PROVISION_USN_ATTRIBUTE)
            if len(delta.items()) > 1:
                delta.dn = refentry.dn
                sam.modify(delta)


def construct_existor_expr(attrs):
    """Construct a exists or LDAP search expression.
    ie (|(foo=*)(bar=*)

    :param attrs: List of attribute on which we want to create the search
                  expression.
    :return: A string representing the expression, if attrs is empty an
             empty string is returned"""
    expr = ""
    if len(attrs) > 0:
        expr = "(|"
        for att in attrs:
            expr = "%s(%s=*)"%(expr,att)
        expr = "%s)"%expr
    return expr

def update_machine_account_password(samdb, secrets_ldb, names):
    """Update (change) the password of the current DC both in the SAM db and in
       secret one

    :param samdb: An LDB object related to the sam.ldb file of a given provision
    :param secrets_ldb: An LDB object related to the secrets.ldb file of a given
                        provision
    :param names: List of key provision parameters"""

    expression = "samAccountName=%s$" % names.netbiosname
    secrets_msg = secrets_ldb.search(expression=expression,
                                        attrs=["secureChannelType"])
    if int(secrets_msg[0]["secureChannelType"][0]) == SEC_CHAN_BDC:
        res = samdb.search(expression=expression, attrs=[])
        assert(len(res) == 1)

        msg = ldb.Message(res[0].dn)
        machinepass = samba.generate_random_password(128, 255)
        msg["userPassword"] = ldb.MessageElement(machinepass,
                                                ldb.FLAG_MOD_REPLACE,
                                                "userPassword")
        samdb.modify(msg)

        res = samdb.search(expression=("samAccountName=%s$" % names.netbiosname),
                     attrs=["msDs-keyVersionNumber"])
        assert(len(res) == 1)
        kvno = int(str(res[0]["msDs-keyVersionNumber"]))
        secChanType = int(secrets_msg[0]["secureChannelType"][0])

        secretsdb_self_join(secrets_ldb, domain=names.domain,
                    realm=names.realm,
                    domainsid=names.domainsid,
                    dnsdomain=names.dnsdomain,
                    netbiosname=names.netbiosname,
                    machinepass=machinepass,
                    key_version_number=kvno,
                    secure_channel_type=secChanType)
    else:
        raise ProvisioningError("Unable to find a Secure Channel"
                                "of type SEC_CHAN_BDC")


def search_constructed_attrs_stored(samdb, rootdn, attrs):
    """Search a given sam DB for calculated attributes that are
    still stored in the db.

    :param samdb: An LDB object pointing to the sam
    :param rootdn: The base DN where the search should start
    :param attrs: A list of attributes to be searched
    :return: A hash with attributes as key and an array of
             array. Each array contains the dn and the associated
             values for this attribute as they are stored in the
             sam."""

    hashAtt = {}
    expr = construct_existor_expr(attrs)
    if expr == "":
        return hashAtt
    entry = samdb.search(expression=expr, base=ldb.Dn(samdb, str(rootdn)),
                         scope=SCOPE_SUBTREE, attrs=attrs,
                         controls=["search_options:1:2","bypassoperational:0"])
    if len(entry) == 0:
        # Nothing anymore
        return hashAtt

    for ent in entry:
        for att in attrs:
            if ent.get(att):
                if hashAtt.has_key(att):
                    hashAtt[att][str(ent.dn).lower()] = str(ent[att])
                else:
                    hashAtt[att] = {}
                    hashAtt[att][str(ent.dn).lower()] = str(ent[att])

    return hashAtt