--- modules/univention/s4connector/s4/__init__.py	(Revision 70207)
+++ modules/univention/s4connector/s4/__init__.py	(Arbeitskopie)
@@ -39,6 +39,7 @@ 
 import univention.debug2 as ud
 from ldap.controls import LDAPControl
 from ldap.controls import SimplePagedResultsControl, LDAPControl
+from ldap.filter import filter_format
 from samba.dcerpc import security
 from samba.ndr import ndr_pack, ndr_unpack
 from samba.dcerpc import misc
@@ -2422,6 +2423,39 @@ 
 				ud.debug(ud.LDAP, ud.ALL, "sync_from_ucs: addlist: %s" % addlist)
 				try:
 					self.lo_s4.lo.add_ext_s(compatible_modstring(object['dn']), compatible_addlist(addlist), serverctrls=ctrls) #FIXME encoding
+				except ldap.ALREADY_EXISTS as ex:
+					sAMAccountName_attr_value = object['attributes'].get('sAMAccountName')[0]
+					objectSid_attr_value = object['attributes'].get('objectSid')[0]
+					objectSid = decode_sid(objectSid_attr_value)
+					if not (sAMAccountName_attr_value and objectSid):
+						raise	## unknown situation
+					filter_s4 = filter_format('(&(sAMAccountName=%s)(objectSid=%s)(isDeleted=TRUE))', (sAMAccountName_attr_value, objectSid))
+					ud.debug(ud.LDAP, ud.WARN, "sync_from_ucs: Error during add, searching for conflicting deleted object in S4. Filter: %s" % filter_s4)
+					result = self.lo_s4.lo.search_ext_s(self.lo_s4.base, ldap.SCOPE_SUBTREE, filter_s4, ['objectClass', 'objectCategory', 'isDeleted', 'isRecycled', 'lastKnownParent'], serverctrls=[self.ctrl_show_deleted, LDAPControl(LDB_CONTROL_DOMAIN_SCOPE_OID, criticality=0)])
+					if not result or len(result)>1:	## the latter would indicate corruption
+						ud.debug(ud.LDAP, ud.WARN,"sync_from_ucs: No conflicting object found.")
+						raise	## unknown situation
+					(deleted_object_dn, deleted_object) = result[0]
+					ud.debug(ud.LDAP, ud.WARN, "sync_from_ucs: Reanimating deleted object in S4: %s" % deleted_object_dn)
+					## Currently tombstone_reanimate.c and tests/python/tombstone_reanimation.py
+					## which implement https://msdn.microsoft.com/en-us/library/cc223467.aspx (MS-ADTS 3.1.1.5.3.7)
+					## are disabled in Samba. Workaround:
+					idx = deleted_object_dn.find('\\0ADEL:')
+					if idx == -1:
+						raise
+					reanimate_modlist = [(ldap.MOD_DELETE, 'isDeleted', ['TRUE'])]
+					reanimate_modlist.append((ldap.MOD_DELETE, 'lastKnownParent', [deleted_object['lastKnownParent'][0]]))
+					reanimate_modlist.append((ldap.MOD_DELETE, 'isRecycled', ['TRUE']))
+					if not deleted_object.get('objectCategory'):
+						top_most_structural_objectclass = deleted_object['objectClass'][-1]
+						result = self.lo_s4.lo.search_ext_s("CN=Schema,CN=Configuration,%s" % self.lo_s4.base, ldap.SCOPE_SUBTREE, filter_format('lDAPDisplayName=%s', (top_most_structural_objectclass,)), ['defaultObjectCategory'])
+						reanimate_modlist.append((ldap.MOD_ADD, 'objectCategory', [result[0][1]['defaultObjectCategory'][0]]))
+					ud.debug(ud.LDAP, ud.ALL,"sync_from_ucs: modlist: %s" % reanimate_modlist)
+					self.lo_s4.lo.modify_ext_s(compatible_modstring(deleted_object_dn), compatible_modlist(reanimate_modlist), serverctrls=[self.ctrl_show_deleted,])
+					ud.debug(ud.LDAP, ud.ALL, "rename_s: from %s to %s parent %s" % (deleted_object_dn, deleted_object_dn[:idx], deleted_object['lastKnownParent'][0]))
+					self.lo_s4.lo.rename_s(compatible_modstring(deleted_object_dn), deleted_object_dn[:idx], newsuperior=deleted_object['lastKnownParent'][0], delold=1)
+					## and retry
+					return self.sync_from_ucs(property_type, object, pre_mapped_ucs_dn, old_dn, old_ucs_object, new_ucs_object)
 				except:
 					ud.debug(ud.LDAP, ud.ERROR, "sync_from_ucs: traceback during add object: %s" % object['dn'])
 					ud.debug(ud.LDAP, ud.ERROR, "sync_from_ucs: traceback due to addlist: %s" % addlist)