[mirror_ifupdown2.git] / ifupdown / ifupdownmain.py

#!/usr/bin/python
#
# Copyright 2014 Cumulus Networks, Inc. All rights reserved.
# Author: Roopa Prabhu, roopa@cumulusnetworks.com
#
# ifupdownMain --
#    ifupdown main module
#

import os
import re
import imp
import pprint
import logging
import sys, traceback
import copy
import json
import ifupdown.statemanager as statemanager
import ifupdown.ifupdownconfig as ifupdownConfig
import ifupdown.ifupdownflags as ifupdownflags
from networkinterfaces import *
from iface import *
from scheduler import *
from collections import deque
from collections import OrderedDict
from graph import *
from sets import Set

"""
.. module:: ifupdownmain
:synopsis: main module for ifupdown package

.. moduleauthor:: Roopa Prabhu <roopa@cumulusnetworks.com>

"""

_tickmark = u'\u2713'
_crossmark = u'\u2717'
_success_sym = '(%s)' %_tickmark
_error_sym = '(%s)' %_crossmark

class ifupdownMainFlags():
    WITH_DEPENDS = False
    ALL = False
    IFACE_CLASS = False
    COMPAT_EXEC_SCRIPTS = False
    STATEMANAGER_ENABLE = True
    STATEMANAGER_UPDATE = True
    ADDONS_ENABLE = False
    DELETE_DEPENDENT_IFACES_WITH_NOCONFIG = False
    SCHED_SKIP_CHECK_UPPERIFACES = False
    CHECK_SHARED_DEPENDENTS = True

class ifacePrivFlags():
    # priv flags to mark iface objects
    BUILTIN = False
    NOCONFIG = False

    def __init__(self, builtin=False, noconfig=False):
        self.BUILTIN = builtin
        self.NOCONFIG = noconfig
    
class ifupdownMain(ifupdownBase):
    """ ifupdown2 main class """

    scripts_dir='/etc/network'
    addon_modules_dir='/usr/share/ifupdown2/addons'
    addon_modules_configfile='/etc/network/ifupdown2/addons.conf'

    # iface dictionary in the below format:
    # { '<ifacename>' : [<ifaceobject1>, <ifaceobject2> ..] }
    # eg:
    # { 'swp1' : [<iface swp1>, <iface swp2> ..] }
    #
    # Each ifaceobject corresponds to a configuration block for
    # that interface
    # The value in the dictionary is a list because the network
    # interface configuration file supports more than one iface section
    # in the interfaces file
    ifaceobjdict = OrderedDict()

    # iface dictionary representing the curr running state of an iface
    # in the below format:
    # {'<ifacename>' : <ifaceobject>}
    ifaceobjcurrdict = OrderedDict()

    # Dictionary representing operation and modules
    # for every operation
    module_ops = OrderedDict([('pre-up', []),
                              ('up' , []),
                              ('post-up' , []),
                              ('query-checkcurr', []),
                              ('query-running', []),
                              ('query-dependency', []),
                              ('query', []),
                              ('query-raw', []),
                              ('pre-down', []),
                              ('down' , []),
                              ('post-down' , [])])

    # For old style /etc/network/ bash scripts
    script_ops = OrderedDict([('pre-up', []),
                                    ('up' , []),
                                    ('post-up' , []),
                                    ('pre-down', []),
                                    ('down' , []),
                                    ('post-down' , [])])

    # Handlers for ops that ifupdown2 owns
    def run_up(self, ifaceobj):
        # Skip link sets on ifaceobjs of type 'vlan' (used for l2 attrs).
        # there is no real interface behind it
        if ifaceobj.type == ifaceType.BRIDGE_VLAN:
            return
        if ifaceobj.link_kind & ifaceLinkKind.VRF:
            return
        if (ifaceobj.addr_method and
            ifaceobj.addr_method == 'manual'):
            return
        if self._delay_admin_state:
            self._delay_admin_state_iface_queue.append(ifaceobj.name)
            return
        # If this object is a link slave, ie its link is controlled
        # by its link master interface, then dont set the link state.
        # But do allow user to change state of the link if the interface
        # is already with its link master (hence the master check).
        if ifaceobj.link_type == ifaceLinkType.LINK_SLAVE:
            return
        if not self.link_exists(ifaceobj.name):
           return
        self.link_up(ifaceobj.name)

    def run_down(self, ifaceobj):
        if ifaceobj.link_kind & ifaceLinkKind.VRF:
            return
        # Skip link sets on ifaceobjs of type 'vlan' (used for l2 attrs)
        # there is no real interface behind it
        if ifaceobj.type == ifaceType.BRIDGE_VLAN:
            return
        if (ifaceobj.addr_method and
            ifaceobj.addr_method == 'manual'):
            return
        if self._delay_admin_state:
            self._delay_admin_state_iface_queue.append(ifaceobj.name)
            return
        # If this object is a link slave, ie its link is controlled
        # by its link master interface, then dont set the link state.
        # But do allow user to change state of the link if the interface
        # is already with its link master (hence the master check).
        if ifaceobj.link_type == ifaceLinkType.LINK_SLAVE:
           return
        if not self.link_exists(ifaceobj.name):
           return
        self.link_down(ifaceobj.name)

    # ifupdown object interface operation handlers
    ops_handlers = OrderedDict([('up', run_up),
                                ('down', run_down)])

    def run_sched_ifaceobj_posthook(self, ifaceobj, op):
        if (ifaceobj.priv_flags and (ifaceobj.priv_flags.BUILTIN or
            ifaceobj.priv_flags.NOCONFIG)):
            return
        if self.flags.STATEMANAGER_UPDATE:
            self.statemanager.ifaceobj_sync(ifaceobj, op)

    # ifupdown object interface scheduler pre and posthooks
    sched_hooks = {'posthook' : run_sched_ifaceobj_posthook}

    def __init__(self, config={},
                 force=False, dryrun=False, nowait=False,
                 perfmode=False, withdepends=False, njobs=1,
                 cache=False, addons_enable=True, statemanager_enable=True,
                 interfacesfile='/etc/network/interfaces',
                 interfacesfileiobuf=None,
                 interfacesfileformat='native',
                 withdefaults=False):
        """This member function initializes the ifupdownmain object.

        Kwargs:
            config (dict):  config dict from /etc/network/ifupdown2/ifupdown2.conf
            force (bool): force interface configuration
            dryrun (bool): dryrun interface configuration
            withdepends (bool): apply interface configuration on all depends
            interfacesfile (str): interfaces file. default is /etc/network/interfaces
            interfacesfileformat (str): default is 'native'. Other choices are 'json'

        Raises:
            AttributeError, KeyError """

        self.logger = logging.getLogger('ifupdown')
        ifupdownflags.flags.FORCE = force
        ifupdownflags.flags.DRYRUN = dryrun
        ifupdownflags.flags.WITHDEFAULTS = withdefaults
        ifupdownflags.flags.NOWAIT = nowait
        ifupdownflags.flags.PERFMODE = perfmode
        ifupdownflags.flags.CACHE = cache

        # Can be used to provide hints for caching
        ifupdownflags.flags.CACHE_FLAGS = 0x0

        self.flags = ifupdownMainFlags()

        self.flags.WITH_DEPENDS = withdepends
        self.flags.STATEMANAGER_ENABLE = statemanager_enable
        self.interfacesfile = interfacesfile
        self.interfacesfileiobuf = interfacesfileiobuf
        self.interfacesfileformat = interfacesfileformat
        self.config = config
        self.logger.debug(self.config)
        self.blacklisted_ifaces_present = False

        self.type = ifaceType.UNKNOWN

        self.flags.DELETE_DEPENDENT_IFACES_WITH_NOCONFIG = False
        self.flags.ADDONS_ENABLE = addons_enable

        self.ifaces = OrderedDict()
        self.njobs = njobs
        self.pp = pprint.PrettyPrinter(indent=4)
        self.modules = OrderedDict({})
        self.module_attrs = {}
        
        self.load_addon_modules(self.addon_modules_dir)
        if self.flags.COMPAT_EXEC_SCRIPTS:
            self.load_scripts(self.scripts_dir)
        self.dependency_graph = OrderedDict({})

        self._cache_no_repeats = {}

        if self.flags.STATEMANAGER_ENABLE:
            try:
                self.statemanager = statemanager.statemanager_api
                self.statemanager.read_saved_state()
            except Exception, e:
                # XXX Maybe we should continue by ignoring old state
                self.logger.warning('error reading state (%s)' %str(e))
                raise
        else:
            self.flags.STATEMANAGER_UPDATE = False
        self._delay_admin_state = True if self.config.get(
                            'delay_admin_state_change', '0') == '1' else False
        self._delay_admin_state_iface_queue = []
        if self._delay_admin_state:
            self.logger.info('\'delay_admin_state_change\' is set. admin ' +
                             'state changes will be delayed till the end.')

        self._link_master_slave = True if self.config.get(
                      'link_master_slave', '0') == '1' else False
        if self._link_master_slave:
            self.logger.info('\'link_master_slave\' is set. slave admin ' +
                             'state changes will be delayed till the ' +
                             'masters admin state change.')

        # squash iface objects for same interface both internal and
        # external representation. It is off by default.
        self._ifaceobj_squash = True if self.config.get(
                            'ifaceobj_squash', '0') == '1' else False

        # squash iface objects for same interface internal
        # representation only. External representation as seen by ifquery
        # will continue to see multiple iface stanzas if it was specified
        # that way by the user. It is on by default.
        self._ifaceobj_squash_internal = True if self.config.get(
                            'ifaceobj_squash_internal', '1') == '1' else False

        # initialize global config object with config passed by the user
        # This makes config available to addon modules
        ifupdownConfig.config = self.config

    def link_master_slave_ignore_error(self, errorstr):
        # If link master slave flag is set, 
        # there may be cases where the lowerdev may not be
        # up resulting in 'Network is down' error
        # This can happen if the lowerdev is a LINK_SLAVE
        # of another interface which is not up yet
        # example of such a case:
        #   bringing up a vlan on a bond interface and the bond
        #   is a LINK_SLAVE of a bridge (in other words the bond is
        #   part of a bridge) which is not up yet
        if self._link_master_slave:
           if 'Network is down':
              return True
        return False

    def get_ifaceobjs(self, ifacename):
        return self.ifaceobjdict.get(ifacename)

    def get_ifaceobjs_saved(self, ifacename):
        """ Return ifaceobjects from statemanager """
        if self.flags.STATEMANAGER_ENABLE:
           return self.statemanager.get_ifaceobjs(ifacename)
        else:
           None

    def get_ifaceobj_first(self, ifacename):
        ifaceobjs = self.get_ifaceobjs(ifacename)
        if ifaceobjs:
            return ifaceobjs[0]
        return None

    def get_ifacenames(self):
        return self.ifaceobjdict.keys()

    def get_iface_obj_last(self, ifacename):
        return self.ifaceobjdict.get(ifacename)[-1]


    def must_follow_upperifaces(self, ifacename):
        #
        # XXX: This bleeds the knowledge of iface
        # types in the infrastructure module.
        # Cant think of a better fix at the moment.
        # In future maybe the module can set a flag
        # to indicate if we should follow upperifaces
        #
        ifaceobj = self.get_ifaceobj_first(ifacename)
        if ifaceobj.type == ifaceType.BRIDGE_VLAN:
            return False
        return True

    def create_n_save_ifaceobj(self, ifacename, priv_flags=None,
                               increfcnt=False):
        """ creates a iface object and adds it to the iface dictionary """
        ifaceobj = iface()
        ifaceobj.name = ifacename
        ifaceobj.priv_flags = priv_flags
        ifaceobj.auto = True
        if not self._link_master_slave:
            ifaceobj.link_type = ifaceLinkType.LINK_NA
        if increfcnt:
            ifaceobj.inc_refcnt()
        self.ifaceobjdict[ifacename] = [ifaceobj]
        return ifaceobj

    def create_n_save_ifaceobjcurr(self, ifaceobj):
        """ creates a copy of iface object and adds it to the iface
            dict containing current iface objects 
        """
        ifaceobjcurr = iface()
        ifaceobjcurr.name = ifaceobj.name
        ifaceobjcurr.type = ifaceobj.type
        ifaceobjcurr.lowerifaces = ifaceobj.lowerifaces
        ifaceobjcurr.priv_flags = copy.deepcopy(ifaceobj.priv_flags)
        ifaceobjcurr.auto = ifaceobj.auto
        self.ifaceobjcurrdict.setdefault(ifaceobj.name,
                                     []).append(ifaceobjcurr)
        return ifaceobjcurr

    def get_ifaceobjcurr(self, ifacename, idx=0):
        ifaceobjlist = self.ifaceobjcurrdict.get(ifacename)
        if not ifaceobjlist:
            return None
        if not idx:
            return ifaceobjlist
        else:
            return ifaceobjlist[idx]

    def get_ifaceobjrunning(self, ifacename):
        return self.ifaceobjrunningdict.get(ifacename)

    def get_iface_refcnt(self, ifacename):
        """ Return iface ref count """
        max = 0
        ifaceobjs = self.get_ifaceobjs(ifacename)
        if not ifaceobjs:
            return 0
        for i in ifaceobjs:
            if i.refcnt > max:
                max = i.refcnt
        return max

    def is_iface_builtin_byname(self, ifacename):
        """ Returns true if iface name is a builtin interface.
        
        A builtin interface is an interface which ifupdown understands.
        The following are currently considered builtin ifaces:
            - vlan interfaces in the format <ifacename>.<vlanid>
        """
        return '.' in ifacename

    def is_ifaceobj_builtin(self, ifaceobj):
        """ Returns true if iface name is a builtin interface.
        
        A builtin interface is an interface which ifupdown understands.
        The following are currently considered builtin ifaces:
            - vlan interfaces in the format <ifacename>.<vlanid>
        """

        return (ifaceobj.priv_flags and ifaceobj.priv_flags.BUILTIN)

    def is_ifaceobj_noconfig(self, ifaceobj):
        """ Returns true if iface object did not have a user defined config.
       
        These interfaces appear only when they are dependents of interfaces
        which have user defined config
        """
        return (ifaceobj.priv_flags and ifaceobj.priv_flags.NOCONFIG)

    def is_iface_noconfig(self, ifacename):
        """ Returns true if iface has no config """

        ifaceobj = self.get_ifaceobj_first(ifacename)
        if not ifaceobj: return True
        return self.is_ifaceobj_noconfig(ifaceobj)

    def check_shared_dependents(self, ifaceobj, dlist):
        """ ABSOLETE: Check if dlist intersects with any other
            interface with slave dependents.
            example: bond and bridges.
            This function logs such errors """
        setdlist = Set(dlist)
        for ifacename, ifacedlist in self.dependency_graph.items():
            if not ifacedlist:
                continue
            check_depends = False
            iobjs = self.get_ifaceobjs(ifacename)
            if not iobjs:
                continue
            for i in iobjs:
                if (i.dependency_type == ifaceDependencyType.MASTER_SLAVE):
                    check_depends = True
            if check_depends:
                common = Set(ifacedlist).intersection(setdlist)
                if common:
                    self.logger.error('misconfig..?. iface %s and %s '
                            %(ifaceobj.name, ifacename) +
                            'seem to share dependents/ports %s' %str(list(common)))

    def _set_iface_role(self, ifaceobj, role, upperifaceobj):
        if (self.flags.CHECK_SHARED_DEPENDENTS and
            (ifaceobj.role & ifaceRole.SLAVE) and
            (role == ifaceRole.SLAVE) and (upperifaceobj.role == ifaceRole.MASTER)):
		self.logger.error("misconfig..? %s %s is enslaved to multiple interfaces %s"
                                  %(ifaceobj.name,
                                    ifaceLinkPrivFlags.get_all_str(ifaceobj.link_privflags), str(ifaceobj.upperifaces)))
                ifaceobj.set_status(ifaceStatus.ERROR)
                return
        ifaceobj.role = role

    def _set_iface_role_n_kind(self, ifaceobj, upperifaceobj):

        if (upperifaceobj.link_kind & ifaceLinkKind.BOND):
            self._set_iface_role(ifaceobj, ifaceRole.SLAVE, upperifaceobj)
            ifaceobj.link_privflags |= ifaceLinkPrivFlags.BOND_SLAVE

        if (upperifaceobj.link_kind & ifaceLinkKind.BRIDGE):
            self._set_iface_role(ifaceobj, ifaceRole.SLAVE, upperifaceobj)
            ifaceobj.link_privflags |= ifaceLinkPrivFlags.BRIDGE_PORT

        if (ifaceobj.link_kind & ifaceLinkKind.VXLAN) \
                and (upperifaceobj.link_kind & ifaceLinkKind.BRIDGE):
            upperifaceobj.link_privflags |= ifaceLinkPrivFlags.BRIDGE_VXLAN

        # vrf masters get processed after slaves, which means
        # check both link_kind vrf and vrf slave
        if ((upperifaceobj.link_kind & ifaceLinkKind.VRF) or
            (ifaceobj.link_privflags & ifaceLinkPrivFlags.VRF_SLAVE)):
            self._set_iface_role(ifaceobj, ifaceRole.SLAVE, upperifaceobj)
            ifaceobj.link_privflags |= ifaceLinkPrivFlags.VRF_SLAVE
        if self._link_master_slave:
            if upperifaceobj.link_type == ifaceLinkType.LINK_MASTER:
                ifaceobj.link_type = ifaceLinkType.LINK_SLAVE
        else:
            upperifaceobj.link_type = ifaceLinkType.LINK_NA
            ifaceobj.link_type = ifaceLinkType.LINK_NA

    def dump_iface_dependency_info(self):
        """ debug funtion to print raw dependency 
        info - lower and upper devices"""

        for ifacename, ifaceobjs in self.ifaceobjdict.iteritems():
            iobj = ifaceobjs[0]
            self.logger.info("%s: refcnt: %d, lower: %s, upper: %s" %(ifacename,
                             self.get_iface_refcnt(ifacename),
                             str(iobj.lowerifaces) if iobj.lowerifaces else [],
                             str(iobj.upperifaces) if iobj.upperifaces else []))


    def preprocess_dependency_list(self, upperifaceobj, dlist, ops):
        """ We go through the dependency list and
            delete or add interfaces from the interfaces dict by
            applying the following rules:
                if flag DELETE_DEPENDENT_IFACES_WITH_NOCONFIG is True:
                    we only consider devices whose configuration was
                    specified in the network interfaces file. We delete
                    any interface whose config was not specified except
                    for vlan devices. vlan devices get special treatment.
                    Even if they are not present they are created and added
                    to the ifacesdict
                elif flag DELETE_DEPENDENT_IFACES_WITH_NOCONFIG is False:
                    we create objects for all dependent devices that are not
                    present in the ifacesdict
        """
        del_list = []

        for d in dlist:
            dilist = self.get_ifaceobjs(d)
            if not dilist:
                ni = None
                if self.is_iface_builtin_byname(d):
                    ni = self.create_n_save_ifaceobj(d,
                            ifacePrivFlags(True, True), True)
                elif not self.flags.DELETE_DEPENDENT_IFACES_WITH_NOCONFIG:
                    ni = self.create_n_save_ifaceobj(d,
                                    ifacePrivFlags(False, True), True)
                else:
                    del_list.append(d)
                if ni:
                    ni.add_to_upperifaces(upperifaceobj.name)
                    self._set_iface_role_n_kind(ni, upperifaceobj)
            else:
                for di in dilist:
                    di.inc_refcnt()
                    di.add_to_upperifaces(upperifaceobj.name)
                    self._set_iface_role_n_kind(di, upperifaceobj)
        for d in del_list:
            dlist.remove(d)

    def preprocess_upperiface(self, lowerifaceobj, ulist, ops):
        for u in ulist:
            if (lowerifaceobj.upperifaces and
                u in lowerifaceobj.upperifaces):
                continue
            lowerifaceobj.add_to_upperifaces(u)
            uifacelist = self.get_ifaceobjs(u)
            if uifacelist:
                for ui in uifacelist:
                    lowerifaceobj.inc_refcnt()
                    self._set_iface_role_n_kind(lowerifaceobj, ui)
                    ui.add_to_lowerifaces(lowerifaceobj.name)

    def query_lowerifaces(self, ifaceobj, ops, ifacenames, type=None):
        """ Gets iface dependents by calling into respective modules """
        ret_dlist = []

        # Get dependents for interface by querying respective modules
        for module in self.modules.values():
            try:
                if ops[0] == 'query-running':
                    if (not hasattr(module,
                        'get_dependent_ifacenames_running')):
                        continue
                    dlist = module.get_dependent_ifacenames_running(ifaceobj)
                else:
                    if (not hasattr(module, 'get_dependent_ifacenames')):
                        continue
                    dlist = module.get_dependent_ifacenames(ifaceobj,
                                        ifacenames)
            except Exception, e:
                self.logger.warn('%s: error getting dependent interfaces (%s)'
                        %(ifaceobj.name, str(e)))
                dlist = None
                pass
            if dlist: ret_dlist.extend(dlist)
        return list(set(ret_dlist))

    def query_upperifaces(self, ifaceobj, ops, ifacenames, type=None):
        """ Gets iface upperifaces by calling into respective modules """
        ret_ulist = []

        # Get upperifaces for interface by querying respective modules
        for module in self.modules.values():
            try:
                if ops[0] == 'query-running':
                    if (not hasattr(module,
                        'get_upper_ifacenames_running')):
                        continue
                    ulist = module.get_upper_ifacenames_running(ifaceobj)
                else:
                    if (not hasattr(module, 'get_upper_ifacenames')):
                        continue
                    ulist = module.get_upper_ifacenames(ifaceobj, ifacenames)
            except Exception, e:
                self.logger.warn('%s: error getting upper interfaces (%s)'
                                 %(ifaceobj.name, str(e)))
                ulist = None
                pass
            if ulist: ret_ulist.extend(ulist)
        return list(set(ret_ulist))

    def populate_dependency_info(self, ops, ifacenames=None):
        """ recursive function to generate iface dependency info """

        if not ifacenames:
            ifacenames = self.ifaceobjdict.keys()

        iqueue = deque(ifacenames)
        while iqueue:
            i = iqueue.popleft()
            # Go through all modules and find dependent ifaces
            dlist = None
            ulist = None
            ifaceobjs = self.get_ifaceobjs(i)
            if not ifaceobjs:
                continue
            dependents_processed = False

            # Store all dependency info in the first ifaceobj
            # but get dependency info from all ifaceobjs
            ifaceobj = ifaceobjs[0]
            for iobj in ifaceobjs:
                ulist = self.query_upperifaces(iobj, ops, ifacenames)
                if iobj.lowerifaces:
                    dependents_processed = True
                    break
                dlist = self.query_lowerifaces(iobj, ops, ifacenames)
                if dlist:
                   break
            if ulist:
                self.preprocess_upperiface(ifaceobj, ulist, ops)
            if dependents_processed:
                continue
            if dlist:
                self.preprocess_dependency_list(ifaceobj,
                                                dlist, ops)
                ifaceobj.lowerifaces = dlist
                [iqueue.append(d) for d in dlist]
            #if not self.dependency_graph.get(i):
            #    self.dependency_graph[i] = dlist

        for i in self.ifaceobjdict.keys():
            iobj = self.get_ifaceobj_first(i)
            if iobj.lowerifaces:
                self.dependency_graph[i] = iobj.lowerifaces
            else:
                self.dependency_graph[i] = []

        if not self.blacklisted_ifaces_present:
            return

        # Walk through the dependency graph and remove blacklisted
        # interfaces that were picked up as dependents
        for i in self.dependency_graph.keys():
            ifaceobj = self.get_ifaceobj_first(i)
            if not ifaceobj:
                continue

            if ifaceobj.blacklisted and not ifaceobj.upperifaces:
                # if blacklisted and was not picked up as a
                # dependent of a upper interface, delete the
                # interface from the dependency graph
                dlist = ifaceobj.lowerifaces
                if dlist:
                    for d in dlist:
                        difaceobjs = self.get_ifaceobjs(d)
                        if not difaceobjs:
                            continue
                        try:
                            for d in difaceobjs:
                                d.dec_refcnt()
                                d.upperifaces.remove(i)
                        except:
                            self.logger.debug('error removing %s from %s upperifaces' %(i, d))
                            pass
                self.logger.debug("populate_dependency_info: deleting blacklisted interface %s" %i)
                del self.dependency_graph[i]
                continue

    def _check_config_no_repeats(self, ifaceobj):
        """ check if object has an attribute that is
        restricted to a single object in the system.
        if yes, warn and return """
        for k,v in self._cache_no_repeats.items():
            iv = ifaceobj.config.get(k)
            if iv and iv[0] == v:
                self.logger.error('ignoring interface %s. ' %ifaceobj.name +
                        'Only one object with attribute ' +
                        '\'%s %s\' allowed.' %(k, v))
                return True
        for k, v in self.config.get('no_repeats', {}).items():
            iv = ifaceobj.config.get(k)
            if iv and iv[0] == v:
                self._cache_no_repeats[k] = v
        return False

    def _save_iface_squash(self, ifaceobj):
        """ squash ifaceobjects belonging to same iface
        into a single object """
        if self._check_config_no_repeats(ifaceobj):
           return
        ifaceobj.priv_flags = ifacePrivFlags()
        if not self._link_master_slave:
           ifaceobj.link_type = ifaceLinkType.LINK_NA
        currentifaceobjlist = self.ifaceobjdict.get(ifaceobj.name)
        if not currentifaceobjlist:
            self.ifaceobjdict[ifaceobj.name] = [ifaceobj]
            return
        if ifaceobj.compare(currentifaceobjlist[0]):
            self.logger.warn('duplicate interface %s found' %ifaceobj.name)
            return
        if ifaceobj.type == ifaceType.BRIDGE_VLAN:
            self.ifaceobjdict[ifaceobj.name].append(ifaceobj)
        else:
            currentifaceobjlist[0].squash(ifaceobj)

    def _save_iface(self, ifaceobj):
        if self._check_config_no_repeats(ifaceobj):
           return
        ifaceobj.priv_flags = ifacePrivFlags()
        if not self._link_master_slave:
           ifaceobj.link_type = ifaceLinkType.LINK_NA
        currentifaceobjlist = self.ifaceobjdict.get(ifaceobj.name)
        if not currentifaceobjlist:
            self.ifaceobjdict[ifaceobj.name]= [ifaceobj]
            if not self._ifaceobj_squash:
                ifaceobj.flags |= ifaceobj.YOUNGEST_SIBLING
            return
        if ifaceobj.compare(currentifaceobjlist[0]):
            self.logger.warn('duplicate interface %s found' %ifaceobj.name)
            return
        if currentifaceobjlist[0].type == ifaceobj.type:
            currentifaceobjlist[0].flags |= ifaceobj.HAS_SIBLINGS
            ifaceobj.flags |= ifaceobj.HAS_SIBLINGS
        # clear the OLDEST_SIBLING from all the siblings
        for iface in self.ifaceobjdict[ifaceobj.name]:
            iface.flags &= ~ifaceobj.OLDEST_SIBLING
        # current sibling is the oldest
        ifaceobj.flags |= ifaceobj.OLDEST_SIBLING
        self.ifaceobjdict[ifaceobj.name].append(ifaceobj)

    def _iface_configattr_syntax_checker(self, attrname, attrval):
        for m, mdict in self.module_attrs.items():
            if not mdict:
                continue
            attrsdict = mdict.get('attrs')
            try:
                a = attrsdict.get(attrname)
                if a:
                    if a.get('deprecated'):
                        newa = a.get('new-attribute')
                        if newa:
                            self.logger.warn('attribute %s is deprecated. Use %s instead' %(attrname, newa))
                        else:
                            self.logger.warn('attribute %s is deprecated'
                                             %attrname)
                    return True
            except AttributeError:
                pass
        return False

    def _ifaceobj_syntax_checker(self, ifaceobj):
        ret = True
        for attrname, attrvalue in ifaceobj.config.items():
            found = False
            for k, v in self.module_attrs.items():
                if v and v.get('attrs', {}).get(attrname):
                    found = True
                    break
            if not found:
                ret = False
                self.logger.warn('%s: unsupported attribute \'%s\'' \
                                 % (ifaceobj.name, attrname))
                continue
        return ret

    def read_iface_config(self):
        """ Reads default network interface config /etc/network/interfaces. """
        ret = True
        nifaces = networkInterfaces(self.interfacesfile,
                        self.interfacesfileiobuf,
                        self.interfacesfileformat,
                        template_engine=self.config.get('template_engine'),
                template_lookuppath=self.config.get('template_lookuppath'))
        if self._ifaceobj_squash or self._ifaceobj_squash_internal:
            nifaces.subscribe('iface_found', self._save_iface_squash)
        else:
            nifaces.subscribe('iface_found', self._save_iface)
        nifaces.subscribe('validateifaceattr',
                          self._iface_configattr_syntax_checker)
        nifaces.subscribe('validateifaceobj', self._ifaceobj_syntax_checker)
        nifaces.load()
        if nifaces.errors or nifaces.warns:
            ret = False
        return ret

    def read_old_iface_config(self):
        """ Reads the saved iface config instead of default iface config.
        And saved iface config is already read by the statemanager """
        self.ifaceobjdict = copy.deepcopy(self.statemanager.ifaceobjdict)

    def _load_addon_modules_config(self):
        """ Load addon modules config file """

        with open(self.addon_modules_configfile, 'r') as f:
            lines = f.readlines()
            for l in lines:
                try:
                    litems = l.strip(' \n\t\r').split(',')
                    if not litems or len(litems) < 2:
                        continue
                    operation = litems[0]
                    mname = litems[1]
                    self.module_ops[operation].append(mname)
                except Exception, e:
                    self.logger.warn('error reading line \'%s\'' %(l, str(e)))
                    continue

    def load_addon_modules(self, modules_dir):
        """ load python modules from modules_dir

        Default modules_dir is /usr/share/ifupdownmodules

        """
        self.logger.info('loading builtin modules from %s' %modules_dir)
        self._load_addon_modules_config()
        if not modules_dir in sys.path:
            sys.path.append(modules_dir)
        try:
            for op, mlist in self.module_ops.items():
                for mname in mlist:
                    if self.modules.get(mname):
                        continue
                    mpath = modules_dir + '/' + mname + '.py'
                    if os.path.exists(mpath):
                        try:
                            m = __import__(mname)
                            mclass = getattr(m, mname)
                        except:
                            raise
                        minstance = mclass()
                        self.modules[mname] = minstance
                        try:
                            self.module_attrs[mname] = minstance.get_modinfo()
                        except:
                            pass
        except: 
            raise

        # Assign all modules to query operations
        self.module_ops['query-checkcurr'] = self.modules.keys()
        self.module_ops['query-running'] = self.modules.keys()
        self.module_ops['query-dependency'] = self.modules.keys()
        self.module_ops['query'] = self.modules.keys()
        self.module_ops['query-raw'] = self.modules.keys()


    def _modules_help(self):
        """ Prints addon modules supported syntax """

        indent = '  '
        for m, mdict in self.module_attrs.items():
            if not mdict:
                continue
            print('%s: %s' %(m, mdict.get('mhelp')))
            attrdict = mdict.get('attrs')
            if not attrdict:
                continue
            try:
                for attrname, attrvaldict in attrdict.items():
                    if attrvaldict.get('compat', False):
                        continue
                    print('%s%s' %(indent, attrname))
                    print('%shelp: %s' %(indent + '  ',
                          attrvaldict.get('help', '')))
                    print ('%srequired: %s' %(indent + '  ',
                            attrvaldict.get('required', False)))
                    default = attrvaldict.get('default')
                    if default:
                        print('%sdefault: %s' %(indent + '  ', default))

                    validrange = attrvaldict.get('validrange')
                    if validrange:
                        print('%svalidrange: %s-%s'
                              %(indent + '  ', validrange[0], validrange[1]))

                    validvals = attrvaldict.get('validvals')
                    if validvals:
                        print('%svalidvals: %s'
                              %(indent + '  ', ','.join(validvals)))

                    examples = attrvaldict.get('example')
                    if not examples:
                        continue

                    print '%sexample:' %(indent + '  ')
                    for e in examples:
                        print '%s%s' %(indent + '    ', e)
            except:
                pass
            print ''
            
    def load_scripts(self, modules_dir):
        """ loading user modules from /etc/network/.

        Note that previously loaded python modules override modules found
        under /etc/network if any

        """

        self.logger.info('looking for user scripts under %s' %modules_dir)
        for op, mlist in self.script_ops.items():
            msubdir = modules_dir + '/if-%s.d' %op
            self.logger.info('loading scripts under %s ...' %msubdir)
            try:
                module_list = os.listdir(msubdir)
                for module in module_list:
                    if  self.modules.get(module) is not None:
                        continue
                    self.script_ops[op].append(
                                    msubdir + '/' + module)
            except: 
                # continue reading
                pass

    def _sched_ifaces(self, ifacenames, ops, skipupperifaces=False,
                      followdependents=True, sort=False):
        self.logger.debug('scheduling \'%s\' for %s'
                          %(str(ops), str(ifacenames)))
        self._pretty_print_ordered_dict('dependency graph',
                    self.dependency_graph)
        ifaceScheduler.sched_ifaces(self, ifacenames, ops,
                        dependency_graph=self.dependency_graph,
                        order=ifaceSchedulerFlags.INORDER
                            if 'down' in ops[0]
                                else ifaceSchedulerFlags.POSTORDER,
                        followdependents=followdependents,
                        skipupperifaces=skipupperifaces,
                        sort=True if (sort or self.flags.IFACE_CLASS) else False)
        return ifaceScheduler.get_sched_status()

    def _render_ifacename(self, ifacename):
        new_ifacenames = []
        vlan_match = re.match("^([\d]+)-([\d]+)", ifacename)
        if vlan_match:
            vlan_groups = vlan_match.groups()
            if vlan_groups[0] and vlan_groups[1]:
                [new_ifacenames.append('%d' %v)
                    for v in range(int(vlan_groups[0]),
                            int(vlan_groups[1])+1)]
        return new_ifacenames

    def _preprocess_ifacenames(self, ifacenames):
        """ validates interface list for config existance.
       
        returns -1 if one or more interface not found. else, returns 0

        """
        new_ifacenames = []
        err_iface = ''
        for i in ifacenames:
            ifaceobjs = self.get_ifaceobjs(i)
            if not ifaceobjs:
                # if name not available, render interface name and check again
                rendered_ifacenames = utils.expand_iface_range(i)
                if rendered_ifacenames:
                    for ri in rendered_ifacenames:
                        ifaceobjs = self.get_ifaceobjs(ri)
                        if not ifaceobjs:
                            err_iface += ' ' + ri
                        else:
                            new_ifacenames.append(ri)
                else:
                    err_iface += ' ' + i
            else:
                new_ifacenames.append(i)
        if err_iface:
            raise Exception('cannot find interfaces:%s' %err_iface)
        return new_ifacenames 

    def _iface_whitelisted(self, auto, allow_classes, excludepats, ifacename):
        """ Checks if interface is whitelisted depending on set of parameters.

        interfaces are checked against the allow_classes and auto lists.

        """

        ret = True

	    # Check if interface matches the exclude patter
        if excludepats:
            for e in excludepats:
                if re.search(e, ifacename):
                    ret = False
        ifaceobjs = self.get_ifaceobjs(ifacename)
        if not ifaceobjs:
            if ret:
                self.logger.debug('iface %s' %ifacename + ' not found')
            return ret
        # If matched exclude pattern, return false
        if not ret:
            for i in ifaceobjs:
                i.blacklisted = True
                self.blacklisted_ifaces_present = True
            return ret
        # Check if interface belongs to the class
        # the user is interested in, if not return false
        if allow_classes:
            ret = False
            for i in ifaceobjs:
                if i.classes:
                    common = Set([allow_classes]).intersection(
                                Set(i.classes))
                    if common:
                        ret = True
            if not ret:
                # If a class was requested and interface does not belong
                # to the class, only then mark the ifaceobjs as blacklisted
                self.blacklisted_ifaces_present = True
                for i in ifaceobjs:
                    i.blacklisted = True
            return ret
        # If the user has requested auto class, check if the interface
        # is marked auto
        if auto:
            ret = False
            for i in ifaceobjs:
                if i.auto:
                    ret = True
            if not ret:
                # If auto was requested and interface was not marked auto,
                # only then mark all of them as blacklisted
                self.blacklisted_ifaces_present = True
                for i in ifaceobjs:
                    i.blacklisted = True
        return ret

    def _compat_conv_op_to_mode(self, op):
        """ Returns old op name to work with existing scripts """
        if op == 'pre-up':
            return 'start'
        elif op == 'pre-down':
            return 'stop'
        else:
            return op

    def generate_running_env(self, ifaceobj, op):
        """ Generates a dictionary with env variables required for
        an interface. Used to support script execution for interfaces.
        """

        cenv = None
        iface_env = ifaceobj.env
        if iface_env:
            cenv = os.environ
            if cenv:
                cenv.update(iface_env)
            else:
                cenv = iface_env
            cenv['MODE'] = self._compat_conv_op_to_mode(op)
        return cenv

    def _save_state(self):
        if (not self.flags.STATEMANAGER_ENABLE or
            not self.flags.STATEMANAGER_UPDATE):
            return
        try:
            # Update persistant iface states
            self.statemanager.save_state()
        except Exception, e:
            if self.logger.isEnabledFor(logging.DEBUG):
                t = sys.exc_info()[2]
                traceback.print_tb(t)
                self.logger.warning('error saving state (%s)' %str(e))

    def set_type(self, type):
        if type == 'iface':
            self.type = ifaceType.IFACE
        elif type == 'vlan':
            self.type = ifaceType.BRIDGE_VLAN
        else:
            self.type = ifaceType.UNKNOWN

    def _process_delay_admin_state_queue(self, op):
        if not self._delay_admin_state_iface_queue:
           return
        if op == 'up':
           func = self.link_up
        elif op == 'down':
           func = self.link_down
        else:
           return
        for i in self._delay_admin_state_iface_queue:
            try:
                if self.link_exists(i):
                   func(i)
            except Exception, e:
                self.logger.warn(str(e))
                pass

    def up(self, ops, auto=False, allow_classes=None, ifacenames=None,
           excludepats=None, printdependency=None, syntaxcheck=False,
           type=None, skipupperifaces=False):
        """This brings the interface(s) up
        
        Args:
            ops (list): list of ops to perform on the interface(s).
            Eg: ['pre-up', 'up', 'post-up'

        Kwargs:
            auto (bool): act on interfaces marked auto
            allow_classes (list): act on interfaces belonging to classes in the list
            ifacenames (list): act on interfaces specified in this list
            excludepats (list): list of patterns of interfaces to exclude
            syntaxcheck (bool): only perform syntax check
        """

        self.set_type(type)

        if allow_classes:
            self.flags.IFACE_CLASS = True
        if not self.flags.ADDONS_ENABLE:
            self.flags.STATEMANAGER_UPDATE = False
        if auto:
            self.flags.ALL = True
            self.flags.WITH_DEPENDS = True
        try:
            iface_read_ret = self.read_iface_config()
        except Exception:
            raise

        if ifacenames:
            ifacenames = self._preprocess_ifacenames(ifacenames)

        # if iface list not given by user, assume all from config file
        if not ifacenames: ifacenames = self.ifaceobjdict.keys()

        # filter interfaces based on auto and allow classes
        filtered_ifacenames = [i for i in ifacenames
                               if self._iface_whitelisted(auto, allow_classes,
                                                excludepats, i)]
        if not filtered_ifacenames:
            raise Exception('no ifaces found matching given allow lists')

        if printdependency:
            self.populate_dependency_info(ops, filtered_ifacenames)
            self.print_dependency(filtered_ifacenames, printdependency)
            return
        else:
            self.populate_dependency_info(ops)

        # If only syntax check was requested, return here.
        # return here because we want to make sure most
        # errors above are caught and reported.
        if syntaxcheck:
            if not iface_read_ret:
                raise Exception()
            return

        try:
            ret = self._sched_ifaces(filtered_ifacenames, ops,
                                     skipupperifaces=skipupperifaces,
                                     followdependents=True
                                     if self.flags.WITH_DEPENDS else False)
        finally:
            self._process_delay_admin_state_queue('up')
            if not ifupdownflags.flags.DRYRUN and self.flags.ADDONS_ENABLE:
                self._save_state()

        if not iface_read_ret or not ret:
            raise Exception()

    def down(self, ops, auto=False, allow_classes=None, ifacenames=None,
             excludepats=None, printdependency=None, usecurrentconfig=False,
             type=None):
        """ down an interface """

        self.set_type(type)

        if allow_classes:
            self.flags.IFACE_CLASS = True
        if not self.flags.ADDONS_ENABLE:
            self.flags.STATEMANAGER_UPDATE = False
        if auto:
            self.flags.ALL = True
            self.flags.WITH_DEPENDS = True
        # For down we need to look at old state, unless usecurrentconfig
        # is set
        if (not usecurrentconfig and self.flags.STATEMANAGER_ENABLE and
                    self.statemanager.ifaceobjdict):
            # Since we are using state manager objects,
            # skip the updating of state manager objects
            self.logger.debug('Looking at old state ..')
            self.read_old_iface_config()
        else:
            # If no old state available 
            try:
                self.read_iface_config()
            except Exception, e:
                raise Exception('error reading iface config (%s)' %str(e))
        if ifacenames:
            # If iface list is given by the caller, always check if iface
            # is present
            try:
               ifacenames = self._preprocess_ifacenames(ifacenames)
            except Exception, e:
               raise Exception('%s' %str(e) +
                       ' (interface was probably never up ?)')

        # if iface list not given by user, assume all from config file
        if not ifacenames: ifacenames = self.ifaceobjdict.keys()

        # filter interfaces based on auto and allow classes
        filtered_ifacenames = [i for i in ifacenames
                               if self._iface_whitelisted(auto, allow_classes,
                                                excludepats, i)]
        if not filtered_ifacenames:
            raise Exception('no ifaces found matching given allow lists ' +
                    '(or interfaces were probably never up ?)')

        if printdependency:
            self.populate_dependency_info(ops, filtered_ifacenames)
            self.print_dependency(filtered_ifacenames, printdependency)
            return
        else:
            self.populate_dependency_info(ops)

        try:
            self._sched_ifaces(filtered_ifacenames, ops,
                               followdependents=True
                               if self.flags.WITH_DEPENDS else False)
        finally:
            self._process_delay_admin_state_queue('down')
            if not ifupdownflags.flags.DRYRUN and self.flags.ADDONS_ENABLE:
                self._save_state()

    def query(self, ops, auto=False, format_list=False, allow_classes=None,
              ifacenames=None,
              excludepats=None, printdependency=None,
              format='native', type=None):
        """ query an interface """

        self.set_type(type)

        # Let us forget internal squashing when it comes to 
        # ifquery. It can surprise people relying of ifquery
        # output
        self._ifaceobj_squash_internal = False

        if allow_classes:
            self.flags.IFACE_CLASS = True
        if self.flags.STATEMANAGER_ENABLE and ops[0] == 'query-savedstate':
            return self.statemanager.dump_pretty(ifacenames)
        self.flags.STATEMANAGER_UPDATE = False
        if auto:
            self.logger.debug('setting flag ALL')
            self.flags.ALL = True
            self.flags.WITH_DEPENDS = True

        if ops[0] == 'query-syntax':
            self._modules_help()
            return
        elif ops[0] == 'query-running':
            # create fake devices to all dependents that dont have config
            map(lambda i: self.create_n_save_ifaceobj(i,
                                ifacePrivFlags(False, True)), ifacenames)
        else:
            try:
                self.read_iface_config()
            except Exception:
                raise

        if ifacenames and ops[0] != 'query-running':
           # If iface list is given, always check if iface is present
           ifacenames = self._preprocess_ifacenames(ifacenames)

        # if iface list not given by user, assume all from config file
        if not ifacenames: ifacenames = self.ifaceobjdict.keys()

        # filter interfaces based on auto and allow classes
        if ops[0] == 'query-running':
            filtered_ifacenames = ifacenames
        else:
            filtered_ifacenames = [i for i in ifacenames
                if self._iface_whitelisted(auto, allow_classes,
                        excludepats, i)]
        if not filtered_ifacenames:
                raise Exception('no ifaces found matching ' +
                        'given allow lists')

        self.populate_dependency_info(ops)
        if ops[0] == 'query-dependency' and printdependency:
            self.print_dependency(filtered_ifacenames, printdependency)
            return

        if format_list and (ops[0] == 'query' or ops[0] == 'query-raw'):
            return self.print_ifaceobjs_list(filtered_ifacenames)

        if ops[0] == 'query' and not ifupdownflags.flags.WITHDEFAULTS:
            return self.print_ifaceobjs_pretty(filtered_ifacenames, format)
        elif ops[0] == 'query-raw':
            return self.print_ifaceobjs_raw(filtered_ifacenames)

        ret = self._sched_ifaces(filtered_ifacenames, ops,
                           followdependents=True
                           if self.flags.WITH_DEPENDS else False)

        if ops[0] == 'query' and ifupdownflags.flags.WITHDEFAULTS:
            return self.print_ifaceobjs_pretty(filtered_ifacenames, format)
        elif ops[0] == 'query-checkcurr':
            ret = self.print_ifaceobjscurr_pretty(filtered_ifacenames, format)
            if ret != 0:
                # if any of the object has an error, signal that silently
                raise Exception('')
        elif ops[0] == 'query-running':
            self.print_ifaceobjsrunning_pretty(filtered_ifacenames, format)
            return

    def _reload_currentlyup(self, upops, downops, auto=True, allow=None,
            ifacenames=None, excludepats=None, usecurrentconfig=False,
            syntaxcheck=False, **extra_args):
        """ reload currently up interfaces """
        new_ifaceobjdict = {}

        # Override auto to true
        auto = True
        try:
            iface_read_ret = self.read_iface_config()
        except:
            raise
        if not self.ifaceobjdict:
            self.logger.warn("nothing to reload ..exiting.")
            return
        already_up_ifacenames = []
        if not ifacenames: ifacenames = self.ifaceobjdict.keys()
        filtered_ifacenames = [i for i in ifacenames
                               if self._iface_whitelisted(auto, allow,
                               excludepats, i)]

        # generate dependency graph of interfaces
        self.populate_dependency_info(upops)

        # If only syntax check was requested, return here.
        # return here because we want to make sure most
        # errors above are caught and reported.
        if syntaxcheck:
            if not iface_read_ret:
                raise Exception()
            return

        if (not usecurrentconfig and self.flags.STATEMANAGER_ENABLE
                and self.statemanager.ifaceobjdict):
            already_up_ifacenames = self.statemanager.ifaceobjdict.keys()

        # Get already up interfaces that still exist in the interfaces file
        already_up_ifacenames_not_present = Set(
                        already_up_ifacenames).difference(ifacenames)
        already_up_ifacenames_still_present = Set(
                        already_up_ifacenames).difference(
                        already_up_ifacenames_not_present)
        interfaces_to_up = Set(already_up_ifacenames_still_present).union(
                                            filtered_ifacenames)

        if (already_up_ifacenames_not_present and
                self.config.get('ifreload_currentlyup_down_notpresent') == '1'):
           self.logger.info('reload: schedule down on interfaces: %s'
                            %str(already_up_ifacenames_not_present))

           # Save a copy of new iface objects and dependency_graph
           new_ifaceobjdict = dict(self.ifaceobjdict)
           new_dependency_graph = dict(self.dependency_graph)

           # old interface config is read into self.ifaceobjdict
           self.read_old_iface_config()

           # reinitialize dependency graph 
           self.dependency_graph = OrderedDict({})
           falready_up_ifacenames_not_present = [i for i in
                                    already_up_ifacenames_not_present
                                    if self._iface_whitelisted(auto, allow,
                                    excludepats, i)]
           self.populate_dependency_info(downops,
                                         falready_up_ifacenames_not_present)
           self._sched_ifaces(falready_up_ifacenames_not_present, downops,
                              followdependents=False, sort=True)
        else:
           self.logger.debug('no interfaces to down ..')

        # Now, run 'up' with new config dict
        # reset statemanager update flag to default
        if auto:
            self.flags.ALL = True
            self.flags.WITH_DEPENDS = True
        if new_ifaceobjdict:
            # and now, ifaceobjdict is back to current config
            self.ifaceobjdict = new_ifaceobjdict
            self.dependency_graph = new_dependency_graph

        if not self.ifaceobjdict:
           return
        self.logger.info('reload: scheduling up on interfaces: %s'
                         %str(interfaces_to_up))
        ret = self._sched_ifaces(interfaces_to_up, upops,
                                 followdependents=True
                                 if self.flags.WITH_DEPENDS else False)
        if ifupdownflags.flags.DRYRUN:
            return
        self._save_state()

        if not iface_read_ret or not ret:
            raise Exception()

    def _reload_default(self, upops, downops, auto=False, allow=None,
            ifacenames=None, excludepats=None, usecurrentconfig=False,
            syntaxcheck=False, **extra_args):
        """ reload interface config """
        new_ifaceobjdict = {}

        try:
            iface_read_ret = self.read_iface_config()
        except:
            raise

        if not self.ifaceobjdict:
            self.logger.warn("nothing to reload ..exiting.")
            return

        if not ifacenames: ifacenames = self.ifaceobjdict.keys()
        new_filtered_ifacenames = [i for i in ifacenames
                               if self._iface_whitelisted(auto, allow,
                               excludepats, i)]
        # generate dependency graph of interfaces
        self.populate_dependency_info(upops)

        # If only syntax check was requested, return here.
        # return here because we want to make sure most
        # errors above are caught and reported.
        if syntaxcheck:
            if not iface_read_ret:
                raise Exception()
            return

        if (not usecurrentconfig and self.flags.STATEMANAGER_ENABLE
                and self.statemanager.ifaceobjdict):
            # Save a copy of new iface objects and dependency_graph
            new_ifaceobjdict = dict(self.ifaceobjdict)
            new_dependency_graph = dict(self.dependency_graph)

            self.ifaceobjdict = OrderedDict({})
            self.dependency_graph = OrderedDict({})

            # if old state is present, read old state and mark op for 'down'
            # followed by 'up' aka: reload
            # old interface config is read into self.ifaceobjdict
            self.read_old_iface_config()
            op = 'reload'
        else:
            # oldconfig not available, continue with 'up' with new config
            op = 'up'
            new_ifaceobjdict = self.ifaceobjdict
            new_dependency_graph = self.dependency_graph

        if op == 'reload' and ifacenames:
            ifacenames = self.ifaceobjdict.keys()
            old_filtered_ifacenames = [i for i in ifacenames
                               if self._iface_whitelisted(auto, allow,
                               excludepats, i)]

            # generate dependency graph of old interfaces,
            # This should make sure built in interfaces are
            # populated. disable check shared dependents as an optimization.
            # these are saved interfaces and dependency for these
            # have been checked before they became part of saved state.
            try:
                self.flags.CHECK_SHARED_DEPENDENTS = False 
                self.populate_dependency_info(upops)
                self.flags.CHECK_SHARED_DEPENDENTS = True
            except Exception, e:
                self.logger.info("error generating dependency graph for "
                                 "saved interfaces (%s)" %str(e))
                pass
            
            # make sure we pick up built-in interfaces
            # if config file had 'ifreload_down_changed' variable
            # set, also look for interfaces that changed to down them
            down_changed = int(self.config.get('ifreload_down_changed', '1'))

            # Generate the interface down list
            # Interfaces that go into the down list:
            #   - interfaces that were present in last config and are not
            #     present in the new config
            #   - interfaces that were changed between the last and current
            #     config
            ifacedownlist = []
            for ifname in self.ifaceobjdict.keys():
                lastifaceobjlist = self.ifaceobjdict.get(ifname)
                if not self.is_ifaceobj_builtin(lastifaceobjlist[0]):
                    # if interface is not built-in and is not in
                    # old filtered ifacenames
                    if ifname not in old_filtered_ifacenames:
                        continue
                objidx = 0
                # If interface is not present in the new file
                # append it to the down list
                newifaceobjlist = new_ifaceobjdict.get(ifname)
                if not newifaceobjlist:
                    ifacedownlist.append(ifname)
                    continue
                # If ifaceobj was present in the old interfaces file,
                # and does not have a config in the new interfaces file
                # but has been picked up as a dependent of another
                # interface, catch it here. This catches a common error
                # for example: remove a bond section from the interfaces
                # file, but leave it around as a bridge port
                # XXX: Ideally its better to just add it to the
                # ifacedownlist. But we will be cautious here 
                # and just print a warning
                if (self.is_ifaceobj_noconfig(newifaceobjlist[0]) and
                    not self.is_ifaceobj_builtin(newifaceobjlist[0]) and
                    lastifaceobjlist[0].is_config_present()):
                    self.logger.warn('%s: misconfig ? removed but still exists as a dependency of %s' %(newifaceobjlist[objidx].name,
                         str(newifaceobjlist[objidx].upperifaces)))
                if not down_changed:
                    continue
                if len(newifaceobjlist) != len(lastifaceobjlist):
                    ifacedownlist.append(ifname)
                    continue

                # If interface has changed between the current file
                # and the last installed append it to the down list
                # compare object list
                for objidx in range(0, len(lastifaceobjlist)):
                    oldobj = lastifaceobjlist[objidx]
                    newobj = newifaceobjlist[objidx]
                    if not newobj.compare(oldobj):
                        ifacedownlist.append(ifname)
                        continue

            if ifacedownlist:
                self.logger.info('reload: scheduling down on interfaces: %s'
                                  %str(ifacedownlist))
                # reinitialize dependency graph 
                self.dependency_graph = OrderedDict({})

                # Generate dependency info for old config
                self.flags.CHECK_SHARED_DEPENDENTS = False
                self.populate_dependency_info(downops, ifacedownlist)
                self.flags.CHECK_SHARED_DEPENDENTS = True

                try:
                    # XXX: Hack to skip checking upperifaces during down.
                    # the dependency list is not complete here
                    # and we dont want to down the upperiface.
                    # Hence during reload, set  this to true.
                    # This is being added to avoid a failure in
                    # scheduler._check_upperifaces when we are dowing
                    # a builtin bridge port 
                    self.flags.SCHED_SKIP_CHECK_UPPERIFACES = True
                    self._sched_ifaces(ifacedownlist, downops,
                                       followdependents=False,
                                       sort=True)
                except Exception, e:
                    self.logger.error(str(e))
                    pass
                finally:
                    self.flags.SCHED_SKIP_CHECK_UPPERIFACES = False
                    self._process_delay_admin_state_queue('down')
            else:
                self.logger.debug('no interfaces to down ..')

        # Now, run 'up' with new config dict
        # reset statemanager update flag to default
        if not new_ifaceobjdict:
            self.logger.debug('no interfaces to up')
            return

        if auto:
            self.flags.ALL = True
            self.flags.WITH_DEPENDS = True
        # and now, we are back to the current config in ifaceobjdict
        self.ifaceobjdict = new_ifaceobjdict
        self.dependency_graph = new_dependency_graph

        self.logger.info('reload: scheduling up on interfaces: %s'
                         %str(new_filtered_ifacenames))
        ifupdownflags.flags.CACHE = True
        try:
            ret = self._sched_ifaces(new_filtered_ifacenames, upops,
                                     followdependents=True
                                     if self.flags.WITH_DEPENDS else False)
        except Exception, e:
            self.logger.error(str(e))
            pass
        finally:
            self._process_delay_admin_state_queue('up')
        if ifupdownflags.flags.DRYRUN:
            return
        self._save_state()

        if not iface_read_ret or not ret:
            raise Exception()

    def reload(self, *args, **kargs):
        """ reload interface config """
        self.logger.debug('reloading interface config ..')
        if kargs.get('currentlyup', False):
            self._reload_currentlyup(*args, **kargs)
        else:
            self._reload_default(*args, **kargs)

    def _pretty_print_ordered_dict(self, prefix, argdict):
        outbuf = prefix + ' {\n'
        for k, vlist in argdict.items():
            outbuf += '\t%s : %s\n' %(k, str(vlist))
        self.logger.debug(outbuf + '}')

    def print_dependency(self, ifacenames, format):
        """ prints iface dependency information """

        if not ifacenames:
            ifacenames = self.ifaceobjdict.keys()
        if format == 'list':
            for k,v in self.dependency_graph.items():
                print '%s : %s' %(k, str(v))
        elif format == 'dot':
            indegrees = {}
            map(lambda i: indegrees.update({i :
                self.get_iface_refcnt(i)}),
                self.dependency_graph.keys())
            graph.generate_dots(self.dependency_graph, indegrees)

    def print_ifaceobjs_list(self, ifacenames):
        for i in ifacenames:
            print i

    def print_ifaceobjs_raw(self, ifacenames):
        """ prints raw lines for ifaces from config file """

        for i in ifacenames:
            for ifaceobj in self.get_ifaceobjs(i):
                if (self.is_ifaceobj_builtin(ifaceobj) or 
                    not ifaceobj.is_config_present()):
                    continue
                ifaceobj.dump_raw(self.logger)
                print '\n'
                if self.flags.WITH_DEPENDS and not self.flags.ALL:
                    dlist = ifaceobj.lowerifaces
                    if not dlist: continue
                    self.print_ifaceobjs_raw(dlist)

    def _get_ifaceobjs_pretty(self, ifacenames, ifaceobjs, running=False):
        """ returns iface obj list """

        for i in ifacenames:
            for ifaceobj in self.get_ifaceobjs(i):
                if ((not running and self.is_ifaceobj_noconfig(ifaceobj)) or
                    (running and not ifaceobj.is_config_present())):
                    continue
                ifaceobjs.append(ifaceobj)
                if self.flags.WITH_DEPENDS and not self.flags.ALL:
                    dlist = ifaceobj.lowerifaces
                    if not dlist: continue
                    self._get_ifaceobjs_pretty(dlist, ifaceobjs, running)

    def print_ifaceobjs_pretty(self, ifacenames, format='native'):
        """ pretty prints iface in format given by keyword arg format """

        ifaceobjs = []
        self._get_ifaceobjs_pretty(ifacenames, ifaceobjs)
        if not ifaceobjs: return
        if format == 'json':
            print json.dumps(ifaceobjs, cls=ifaceJsonEncoder,
                             indent=4, separators=(',', ': '))
        else:
            expand = int(self.config.get('ifquery_ifacename_expand_range', '0'))
            for i in ifaceobjs:
                if not expand and (i.flags & iface.IFACERANGE_ENTRY):
                    # print only the first one
                    if i.flags & iface.IFACERANGE_START:
                       i.dump_pretty(use_realname=True)
                else:
                    i.dump_pretty()

    def _get_ifaceobjscurr_pretty(self, ifacenames, ifaceobjs):
        ret = 0
        for i in ifacenames:
            ifaceobjscurr = self.get_ifaceobjcurr(i)
            if not ifaceobjscurr: continue
            for ifaceobj in ifaceobjscurr:
                if (ifaceobj.status == ifaceStatus.NOTFOUND or
                    ifaceobj.status == ifaceStatus.ERROR):
                    ret = 1
                if self.is_ifaceobj_noconfig(ifaceobj):
                    continue
                ifaceobjs.append(ifaceobj)
                if self.flags.WITH_DEPENDS and not self.flags.ALL:
                    dlist = ifaceobj.lowerifaces
                    if not dlist: continue
                    dret = self._get_ifaceobjscurr_pretty(dlist, ifaceobjs)
                    if dret: ret = 1
        return ret

    def print_ifaceobjscurr_pretty(self, ifacenames, format='native'):
        """ pretty prints current running state of interfaces with status.

        returns 1 if any of the interface has an error,
        else returns 0
        """

        ifaceobjs = []
        ret = self._get_ifaceobjscurr_pretty(ifacenames, ifaceobjs)
        if not ifaceobjs: return

        # override ifaceStatusUserStrs
        ifaceStatusUserStrs.SUCCESS = self.config.get('ifquery_check_success_str', _success_sym)
        ifaceStatusUserStrs.ERROR = self.config.get('ifquery_check_error_str', _error_sym)
        ifaceStatusUserStrs.UNKNOWN = self.config.get('ifquery_check_unknown_str', '')
        if format == 'json':
            print json.dumps(ifaceobjs, cls=ifaceJsonEncoderWithStatus,
                             indent=2, separators=(',', ': '))
        else:
            map(lambda i: i.dump_pretty(with_status=True), ifaceobjs)
        return ret

    def print_ifaceobjsrunning_pretty(self, ifacenames, format='native'):
        """ pretty prints iface running state """

        ifaceobjs = []
        self._get_ifaceobjs_pretty(ifacenames, ifaceobjs, running=True)
        if not ifaceobjs: return
        if format == 'json':
            print json.dumps(ifaceobjs, cls=ifaceJsonEncoder, indent=2,
                       separators=(',', ': '))
        else:
            map(lambda i: i.dump_pretty(), ifaceobjs)

    def _dump(self):
        print 'ifupdown main object dump'
        print self.pp.pprint(self.modules)
        print self.pp.pprint(self.ifaceobjdict)

    def _dump_ifaceobjs(self, ifacenames):
        for i in ifacenames:
            ifaceobjs = self.get_ifaceobjs(i)
            for i in ifaceobjs:
                i.dump(self.logger)
                print '\n'