datapath: Additional fixes for datapath device renaming.

[ovs.git] / xenserver / opt_xensource_libexec_interface-reconfigure

#!/usr/bin/python
#
# Copyright (c) 2008,2009 Citrix Systems, Inc. All rights reserved.
# Copyright (c) 2009 Nicira Networks.
#
"""Usage:

    %(command-name)s --session <SESSION-REF> --pif <PIF-REF> [up|down|rewrite]
    %(command-name)s --force <BRIDGE> [up|down|rewrite <CONFIG>]
    %(command-name)s --force all down

    where,
          <CONFIG> = --device=<INTERFACE> --mode=dhcp
          <CONFIG> = --device=<INTERFACE> --mode=static --ip=<IPADDR> --netmask=<NM> [--gateway=<GW>]

  Options:
    --session		A session reference to use to access the xapi DB
    --pif               A PIF reference.
    --force-interface	An interface name. Mutually exclusive with --session/--pif.

  Either both --session and --pif  or just --pif-uuid.
  
  <ACTION> is either "up" or "down" or "rewrite"
"""

#
# Undocumented parameters for test & dev:
#
#  --output-directory=<DIR>	Write configuration to <DIR>. Also disables actually
#                               raising/lowering the interfaces
#  --pif-uuid			A PIF UUID, use instead of --session/--pif.
#
#
#
# Notes:
# 1. Every pif belongs to exactly one network
# 2. Every network has zero or one pifs
# 3. A network may have an associated bridge, allowing vifs to be attached
# 4. A network may be bridgeless (there's no point having a bridge over a storage pif)

# XXX: --force-interface=all down

# XXX: --force-interface rewrite

# XXX: Sometimes this leaves "orphaned" datapaths, e.g. a datapath whose
#      only port is the local port.  Should delete those.

# XXX: This can leave crud in ovs-vswitchd.conf in this scenario:
#      - Create bond in XenCenter.
#      - Create VLAN on bond in XenCenter.
#      - Attempt to delete bond in XenCenter (this will fail because there
#        is a VLAN on the bond, although the error may not be reported
#        until the next step)
#      - Delete VLAN in XenCenter.
#      - Delete bond in XenCenter.
# At this point there will still be some configuration data for the bond
# or the VLAN in ovs-vswitchd.conf.

import XenAPI
import os, sys, getopt, time, signal
import syslog
import traceback
import time
import re
import pickle
import random

output_directory = None

db = None
management_pif = None

dbcache_file = "/etc/ovs-vswitch.dbcache"
vswitch_config_dir = "/etc/openvswitch"

class Usage(Exception):
    def __init__(self, msg):
        Exception.__init__(self)
        self.msg = msg

class Error(Exception):
    def __init__(self, msg):
        Exception.__init__(self)
        self.msg = msg

class ConfigurationFile(object):
    """Write a file, tracking old and new versions.

    Supports writing a new version of a file and applying and
    reverting those changes.
    """

    __STATE = {"OPEN":"OPEN",
               "NOT-APPLIED":"NOT-APPLIED", "APPLIED":"APPLIED",
               "REVERTED":"REVERTED", "COMMITTED": "COMMITTED"}
    
    def __init__(self, fname, path="/etc/sysconfig/network-scripts"):

        self.__state = self.__STATE['OPEN']
        self.__fname = fname
        self.__children = []
        
        if debug_mode():
            dirname = output_directory
        else:
            dirname = path
            
        self.__path    = os.path.join(dirname, fname)
        self.__oldpath = os.path.join(dirname, "." + fname + ".xapi-old")
        self.__newpath = os.path.join(dirname, "." + fname + ".xapi-new")
        self.__unlink = False
        
        self.__f = open(self.__newpath, "w")

    def attach_child(self, child):
        self.__children.append(child)

    def path(self):
        return self.__path

    def readlines(self):
        try:
            return open(self.path()).readlines()
        except:
            return ""
        
    def write(self, args):
        if self.__state != self.__STATE['OPEN']:
            raise Error("Attempt to write to file in state %s" % self.__state)
        self.__f.write(args)

    def unlink(self):
        if self.__state != self.__STATE['OPEN']:
            raise Error("Attempt to unlink file in state %s" % self.__state)
        self.__unlink = True
        self.__f.close()
        self.__state = self.__STATE['NOT-APPLIED']
    
    def close(self):
        if self.__state != self.__STATE['OPEN']:
            raise Error("Attempt to close file in state %s" % self.__state)
        
        self.__f.close()
        self.__state = self.__STATE['NOT-APPLIED']

    def changed(self):
        if self.__state != self.__STATE['NOT-APPLIED']:
            raise Error("Attempt to compare file in state %s" % self.__state)

        return True

    def apply(self):
        if self.__state != self.__STATE['NOT-APPLIED']:
            raise Error("Attempt to apply configuration from state %s" % self.__state)

        for child in self.__children:
            child.apply()

        log("Applying changes to %s configuration" % self.__fname)

        # Remove previous backup.
        if os.access(self.__oldpath, os.F_OK):
            os.unlink(self.__oldpath)

        # Save current configuration.
        if os.access(self.__path, os.F_OK):
            os.link(self.__path, self.__oldpath)
            os.unlink(self.__path)

        # Apply new configuration.
        assert(os.path.exists(self.__newpath))
        if not self.__unlink:
            os.link(self.__newpath, self.__path)
        else:
            pass # implicit unlink of original file 

        # Remove temporary file.
        os.unlink(self.__newpath)

        self.__state = self.__STATE['APPLIED']

    def revert(self):
        if self.__state != self.__STATE['APPLIED']:
            raise Error("Attempt to revert configuration from state %s" % self.__state)

        for child in self.__children:
            child.revert()

        log("Reverting changes to %s configuration" % self.__fname)

        # Remove existing new configuration
        if os.access(self.__newpath, os.F_OK):
            os.unlink(self.__newpath)

        # Revert new configuration.
        if os.access(self.__path, os.F_OK):
            os.link(self.__path, self.__newpath)
            os.unlink(self.__path)

        # Revert to old configuration.
        if os.access(self.__oldpath, os.F_OK):
            os.link(self.__oldpath, self.__path)
            os.unlink(self.__oldpath)

        # Leave .*.xapi-new as an aid to debugging.
        
        self.__state = self.__STATE['REVERTED']
    
    def commit(self):
        if self.__state != self.__STATE['APPLIED']:
            raise Error("Attempt to commit configuration from state %s" % self.__state)

        for child in self.__children:
            child.commit()

        log("Committing changes to %s configuration" % self.__fname)
        
        if os.access(self.__oldpath, os.F_OK):
            os.unlink(self.__oldpath)
        if os.access(self.__newpath, os.F_OK):
            os.unlink(self.__newpath)

        self.__state = self.__STATE['COMMITTED']

def debug_mode():
    return output_directory is not None

def log(s):
    if debug_mode():
        print >>sys.stderr, s
    else:
        syslog.syslog(s)

def check_allowed(pif):
    pifrec = db.get_pif_record(pif)
    try:
        f = open("/proc/ardence")
        macline = filter(lambda x: x.startswith("HWaddr:"), f.readlines())
        f.close()
        if len(macline) == 1:
            p = re.compile(".*\s%(MAC)s\s.*" % pifrec, re.IGNORECASE)
            if p.match(macline[0]):
                log("Skipping PVS device %(device)s (%(MAC)s)" % pifrec)
                return False
    except IOError:
        pass
    return True

def interface_exists(i):
    return os.path.exists("/sys/class/net/" + i)

def get_netdev_mac(device):
    try:
        return read_first_line_of_file("/sys/class/net/%s/address" % device)
    except:
        # Probably no such device.
        return None

def get_netdev_tx_queue_len(device):
    try:
        return int(read_first_line_of_file("/sys/class/net/%s/tx_queue_len"
                                           % device))
    except:
        # Probably no such device.
        return None

def get_netdev_by_mac(mac):
    maybe = None
    for device in os.listdir("/sys/class/net"):
        dev_mac = get_netdev_mac(device)
        if dev_mac and mac.lower() == dev_mac.lower():
            if get_netdev_tx_queue_len(device):
                return device
            if not maybe:
                # Probably a datapath internal port.
                maybe = device
    return maybe

class DatabaseCache(object):
    def __init__(self, session_ref=None, cache_file=None):
        if session_ref and cache_file:
            raise Error("can't specify session reference and cache file")

        if cache_file == None:
            session = XenAPI.xapi_local()

            if not session_ref:
                log("No session ref given on command line, logging in.")
                session.xenapi.login_with_password("root", "")
            else:
                session._session = session_ref

            try:
                self.__vlans = session.xenapi.VLAN.get_all_records()
                self.__bonds = session.xenapi.Bond.get_all_records()
                self.__pifs = session.xenapi.PIF.get_all_records()
                self.__networks = session.xenapi.network.get_all_records()
            finally:
                if not session_ref:
                    session.xenapi.session.logout()
        else:
            log("Loading xapi database cache from %s" % cache_file)
            f = open(cache_file, 'r')
            members = pickle.load(f)
            self.extras = pickle.load(f)
            f.close()

            self.__vlans = members['vlans']
            self.__bonds = members['bonds']
            self.__pifs = members['pifs']
            self.__networks = members['networks']

    def save(self, cache_file, extras):
        f = open(cache_file, 'w')
        pickle.dump({'vlans': self.__vlans,
                     'bonds': self.__bonds,
                     'pifs': self.__pifs,
                     'networks': self.__networks}, f)
        pickle.dump(extras, f)
        f.close()

    def get_pif_by_uuid(self, uuid):
        pifs = map(lambda (ref,rec): ref,
                  filter(lambda (ref,rec): uuid == rec['uuid'],
                         self.__pifs.items()))
        if len(pifs) == 0:
            raise Error("Unknown PIF \"%s\"" % uuid)
        elif len(pifs) > 1:
            raise Error("Non-unique PIF \"%s\"" % uuid)

        return pifs[0]

    def get_pifs_by_record(self, record):
        """record is partial pif record.
        Get the pif(s) whose record matches.
        """
        def match(pifrec):
            for key in record:
                if record[key] != pifrec[key]:
                    return False
            return True
            
        return map(lambda (ref,rec): ref,
                   filter(lambda (ref,rec): match(rec),
                          self.__pifs.items()))

    def get_pif_by_record(self, record):
        """record is partial pif record.
        Get the pif whose record matches.
        """
        pifs = self.get_pifs_by_record(record)
        if len(pifs) == 0:
            raise Error("No matching PIF \"%s\"" % str(record))
        elif len(pifs) > 1:
            raise Error("Multiple matching PIFs \"%s\"" % str(record))

        return pifs[0]

    def get_pif_by_bridge(self, host, bridge):
        networks = map(lambda (ref,rec): ref,
                       filter(lambda (ref,rec): rec['bridge'] == bridge,
                              self.__networks.items()))
        if len(networks) == 0:
            raise Error("No matching network \"%s\"")

        answer = None
        for network in networks:
            nwrec = self.get_network_record(network)
            for pif in nwrec['PIFs']:
                pifrec = self.get_pif_record(pif)
                if pifrec['host'] != host:
                    continue
                if answer:
                    raise Error("Multiple PIFs on %s for network %s" % (host, bridge))
                answer = pif
        if not answer:
            raise Error("No PIF on %s for network %s" % (host, bridge))
        return answer

    def get_pif_record(self, pif):
        if self.__pifs.has_key(pif):
            return self.__pifs[pif]
        raise Error("Unknown PIF \"%s\"" % pif)
    def get_all_pifs(self):
        return self.__pifs
    def pif_exists(self, pif):
        return self.__pifs.has_key(pif)
    
    def get_management_pif(self, host):
        """ Returns the management pif on host
        """
        all = self.get_all_pifs()
        for pif in all: 
            pifrec = self.get_pif_record(pif)
            if pifrec['management'] and pifrec['host'] == host :
                return pif
        return None

    def get_network_record(self, network):
        if self.__networks.has_key(network):
            return self.__networks[network]
        raise Error("Unknown network \"%s\"" % network)
    def get_all_networks(self):
        return self.__networks

    def get_bond_record(self, bond):
        if self.__bonds.has_key(bond):
            return self.__bonds[bond]
        else:
            return None
        
    def get_vlan_record(self, vlan):
        if self.__vlans.has_key(vlan):
            return self.__vlans[vlan]
        else:
            return None
            
def bridge_name(pif):
    """Return the bridge name associated with pif, or None if network is bridgeless"""
    pifrec = db.get_pif_record(pif)
    nwrec = db.get_network_record(pifrec['network'])

    if nwrec['bridge']:
        # TODO: sanity check that nwrec['bridgeless'] != 'true'
        return nwrec['bridge']
    else:
        # TODO: sanity check that nwrec['bridgeless'] == 'true'
        return None

def interface_name(pif):
    """Construct an interface name from the given PIF record."""

    pifrec = db.get_pif_record(pif)

    if pifrec['VLAN'] == '-1':
        return pifrec['device']
    else:
        return "%(device)s.%(VLAN)s" % pifrec

def datapath_name(pif):
    """Return the OpenFlow datapath name associated with pif.
For a non-VLAN PIF, the datapath name is the bridge name.
For a VLAN PIF, the datapath name is the bridge name for the PIF's VLAN slave.
(xapi will create a datapath named with the bridge name even though we won't
use it.)
"""

    pifrec = db.get_pif_record(pif)

    if pifrec['VLAN'] == '-1':
        return bridge_name(pif)
    else:
        return bridge_name(get_vlan_slave_of_pif(pif))

def ipdev_name(pif):
    """Return the the name of the network device that carries the
IP configuration (if any) associated with pif.
The ipdev name is the same as the bridge name.
"""

    pifrec = db.get_pif_record(pif)
    return bridge_name(pif)

def get_physdev_pifs(pif):
    """Return the PIFs for the physical network device(s) associated with pif.
For a VLAN PIF, this is the VLAN slave's physical device PIF.
For a bond master PIF, these are the bond slave PIFs.
For a non-VLAN, non-bond master PIF, the PIF is its own physical device PIF.
"""

    pifrec = db.get_pif_record(pif)

    if pifrec['VLAN'] != '-1':
        return [get_vlan_slave_of_pif(pif)]
    elif len(pifrec['bond_master_of']) != 0:
        return get_bond_slaves_of_pif(pif)
    else:
        return [pif]

def get_physdev_names(pif):
    """Return the name(s) of the physical network device(s) associated with pif.
For a VLAN PIF, the physical devices are the VLAN slave's physical devices.
For a bond master PIF, the physical devices are the bond slaves.
For a non-VLAN, non-bond master PIF, the physical device is the PIF itself.
"""

    return [db.get_pif_record(phys)['device'] for phys in get_physdev_pifs(pif)]

def log_pif_action(action, pif):
    pifrec = db.get_pif_record(pif)
    pifrec['action'] = action
    pifrec['interface-name'] = interface_name(pif)
    if action == "rewrite":
        pifrec['message'] = "Rewrite PIF %(uuid)s configuration" % pifrec
    else:
        pifrec['message'] = "Bring %(action)s PIF %(uuid)s" % pifrec
    log("%(message)s: %(interface-name)s configured as %(ip_configuration_mode)s" % pifrec)

def get_bond_masters_of_pif(pif):
    """Returns a list of PIFs which are bond masters of this PIF"""

    pifrec = db.get_pif_record(pif)

    bso = pifrec['bond_slave_of']

    # bond-slave-of is currently a single reference but in principle a
    # PIF could be a member of several bonds which are not
    # concurrently attached. Be robust to this possibility.
    if not bso or bso == "OpaqueRef:NULL":
        bso = []
    elif not type(bso) == list:
        bso = [bso]

    bondrecs = [db.get_bond_record(bond) for bond in bso]
    bondrecs = [rec for rec in bondrecs if rec]

    return [bond['master'] for bond in bondrecs]

def get_bond_slaves_of_pif(pif):
    """Returns a list of PIFs which make up the given bonded pif."""
    
    pifrec = db.get_pif_record(pif)
    host = pifrec['host']

    bmo = pifrec['bond_master_of']
    if len(bmo) > 1:
        raise Error("Bond-master-of contains too many elements")
    
    if len(bmo) == 0:
        return []
    
    bondrec = db.get_bond_record(bmo[0])
    if not bondrec:
        raise Error("No bond record for bond master PIF")

    return bondrec['slaves']

def get_vlan_slave_of_pif(pif):
    """Find the PIF which is the VLAN slave of pif.

Returns the 'physical' PIF underneath the a VLAN PIF @pif."""
    
    pifrec = db.get_pif_record(pif)

    vlan = pifrec['VLAN_master_of']
    if not vlan or vlan == "OpaqueRef:NULL":
        raise Error("PIF is not a VLAN master")

    vlanrec = db.get_vlan_record(vlan)
    if not vlanrec:
        raise Error("No VLAN record found for PIF")

    return vlanrec['tagged_PIF']

def get_vlan_masters_of_pif(pif):
    """Returns a list of PIFs which are VLANs on top of the given pif."""
    
    pifrec = db.get_pif_record(pif)
    vlans = [db.get_vlan_record(v) for v in pifrec['VLAN_slave_of']]
    return [v['untagged_PIF'] for v in vlans if v and db.pif_exists(v['untagged_PIF'])]

def interface_deconfigure_commands(interface):
    # The use of [!0-9] keeps an interface of 'eth0' from matching
    # VLANs attached to eth0 (such as 'eth0.123'), which are distinct
    # interfaces.
    return ['--del-match=bridge.*.port=%s' % interface,
            '--del-match=bonding.%s.[!0-9]*' % interface,
            '--del-match=bonding.*.slave=%s' % interface,
            '--del-match=vlan.%s.[!0-9]*' % interface,
            '--del-match=port.%s.[!0-9]*' % interface,
            '--del-match=iface.%s.[!0-9]*' % interface]

def run_command(command):
    log("Running command: " + ' '.join(command))
    if os.spawnl(os.P_WAIT, command[0], *command) != 0:
        log("Command failed: " + ' '.join(command))
        return False
    return True

def rename_netdev(old_name, new_name):
    log("Changing the name of %s to %s" % (old_name, new_name))
    run_command(['/sbin/ifconfig', old_name, 'down'])
    if not run_command(['/sbin/ip', 'link', 'set', old_name,
                        'name', new_name]):
        raise Error("Could not rename %s to %s" % (old_name, new_name))

# Check whether 'pif' exists and has the correct MAC.
# If not, try to find a device with the correct MAC and rename it.
# 'already_renamed' is used to avoid infinite recursion.
def remap_pif(pif, already_renamed=[]):
    pifrec = db.get_pif_record(pif)
    device = pifrec['device']
    mac = pifrec['MAC']

    # Is there a network device named 'device' at all?
    device_exists = interface_exists(device)
    if device_exists:
        # Yes.  Does it have MAC 'mac'?
        found_mac = get_netdev_mac(device)
        if found_mac and mac.lower() == found_mac.lower():
            # Yes, everything checks out the way we want.  Nothing to do.
            return
    else:
        log("No network device %s" % device)

    # What device has MAC 'mac'?
    cur_device = get_netdev_by_mac(mac)
    if not cur_device:
        log("No network device has MAC %s" % mac)
        return

    # First rename 'device', if it exists, to get it out of the way
    # for 'cur_device' to replace it.
    if device_exists:
        rename_netdev(device, "dev%d" % random.getrandbits(24))

    # Rename 'cur_device' to 'device'.
    rename_netdev(cur_device, device)

def read_first_line_of_file(name):
    file = None
    try:
        file = open(name, 'r')
        return file.readline().rstrip('\n')
    finally:
        if file != None:
            file.close()

def down_netdev(interface, deconfigure=True):
    if not interface_exists(interface):
        log("down_netdev: interface %s does not exist, ignoring" % interface)
        return
    if deconfigure:
        # Kill dhclient.
        pidfile_name = '/var/run/dhclient-%s.pid' % interface
        try:
            os.kill(int(read_first_line_of_file(pidfile_name)), signal.SIGTERM)
        except:
            pass

        # Remove dhclient pidfile.
        try:
            os.remove(pidfile_name)
        except:
            pass
        
        run_command(["/sbin/ifconfig", interface, '0.0.0.0'])

    run_command(["/sbin/ifconfig", interface, 'down'])

def up_netdev(interface):
    run_command(["/sbin/ifconfig", interface, 'up'])

def find_distinguished_pifs(pif):
    """Returns the PIFs on host that own DNS and the default route.
The peerdns pif will be the one with pif::other-config:peerdns=true, or the mgmt pif if none have this set.
The gateway pif will be the one with pif::other-config:defaultroute=true, or the mgmt pif if none have this set.

Note: we prune out the bond master pif (if it exists).
This is because when we are called to bring up an interface with a bond master, it is implicit that
we should bring down that master."""

    pifrec = db.get_pif_record(pif)
    host = pifrec['host']

    pifs_on_host = [ __pif for __pif in db.get_all_pifs() if
                     db.get_pif_record(__pif)['host'] == host and 
                     (not  __pif in get_bond_masters_of_pif(pif)) ]

    peerdns_pif = None
    defaultroute_pif = None
    
    # loop through all the pifs on this host looking for one with
    #   other-config:peerdns = true, and one with
    #   other-config:default-route=true
    for __pif in pifs_on_host:
        __pifrec = db.get_pif_record(__pif)
        __oc = __pifrec['other_config']
        if __oc.has_key('peerdns') and __oc['peerdns'] == 'true':
            if peerdns_pif == None:
                peerdns_pif = __pif
            else:
                log('Warning: multiple pifs with "peerdns=true" - choosing %s and ignoring %s' % \
                        (db.get_pif_record(peerdns_pif)['device'], __pifrec['device']))
        if __oc.has_key('defaultroute') and __oc['defaultroute'] == 'true':
            if defaultroute_pif == None:
                defaultroute_pif = __pif
            else:
                log('Warning: multiple pifs with "defaultroute=true" - choosing %s and ignoring %s' % \
                        (db.get_pif_record(defaultroute_pif)['device'], __pifrec['device']))
    
    # If no pif is explicitly specified then use the mgmt pif for peerdns/defaultroute
    if peerdns_pif == None:
        peerdns_pif = management_pif
    if defaultroute_pif == None:
        defaultroute_pif = management_pif

    return peerdns_pif, defaultroute_pif

def run_ethtool(device, oc):
    # Run "ethtool -s" if there are any settings.
    settings = []
    if oc.has_key('ethtool-speed'):
        val = oc['ethtool-speed']
        if val in ["10", "100", "1000"]:
            settings += ['speed', val]
        else:
            log("Invalid value for ethtool-speed = %s. Must be 10|100|1000." % val)
    if oc.has_key('ethtool-duplex'):
        val = oc['ethtool-duplex']
        if val in ["10", "100", "1000"]:
            settings += ['duplex', 'val']
        else:
            log("Invalid value for ethtool-duplex = %s. Must be half|full." % val)
    if oc.has_key('ethtool-autoneg'):
        val = oc['ethtool-autoneg']
        if val in ["true", "on"]:
            settings += ['autoneg', 'on']
        elif val in ["false", "off"]:
            settings += ['autoneg', 'off']
        else:
            log("Invalid value for ethtool-autoneg = %s. Must be on|true|off|false." % val)
    if settings:
        run_command(['/sbin/ethtool', '-s', device] + settings)

    # Run "ethtool -K" if there are any offload settings.
    offload = []
    for opt in ("rx", "tx", "sg", "tso", "ufo", "gso"):
        if oc.has_key("ethtool-" + opt):
            val = oc["ethtool-" + opt]
            if val in ["true", "on"]:
                offload += [opt, 'on']
            elif val in ["false", "off"]:
                offload += [opt, 'off']
            else:
                log("Invalid value for ethtool-%s = %s. Must be on|true|off|false." % (opt, val))
    if offload:
        run_command(['/sbin/ethtool', '-K', device] + offload)

def mtu_setting(oc):
    if oc.has_key('mtu'):
        try:
            int(oc['mtu'])      # Check that the value is an integer
            return ['mtu', oc['mtu']]
        except ValueError, x:
            log("Invalid value for mtu = %s" % mtu)
    return []

def configure_local_port(pif):
    pifrec = db.get_pif_record(pif)
    datapath = datapath_name(pif)
    ipdev = ipdev_name(pif)

    host = pifrec['host']
    nw = pifrec['network']
    nwrec = db.get_network_record(nw)

    pif_oc = pifrec['other_config']
    nw_oc = nwrec['other_config']

    # IP (except DHCP) and MTU.
    ifconfig_argv = ['/sbin/ifconfig', ipdev, 'up']
    gateway = ''
    if pifrec['ip_configuration_mode'] == "DHCP":
        pass
    elif pifrec['ip_configuration_mode'] == "Static":
        ifconfig_argv += [pifrec['IP']]
        ifconfig_argv += ['netmask', pifrec['netmask']]
        gateway = pifrec['gateway']
    elif pifrec['ip_configuration_mode'] == "None":
        # Nothing to do.
        pass
    else:
        raise Error("Unknown IP-configuration-mode %s" % pifrec['ip_configuration_mode'])
    ifconfig_argv += mtu_setting(nw_oc)
    run_command(ifconfig_argv)
    
    (peerdns_pif, defaultroute_pif) = find_distinguished_pifs(pif)

    # /etc/resolv.conf
    if peerdns_pif == pif:
        f = ConfigurationFile('resolv.conf', "/etc")
        if pif_oc.has_key('domain'):
            f.write("search %s\n" % pif_oc['domain'])
        for dns in pifrec['DNS'].split(","): 
            f.write("nameserver %s\n" % dns)
        f.close()
        f.apply()
        f.commit()

    # Routing.
    if defaultroute_pif == pif and gateway != '':
        run_command(['/sbin/ip', 'route', 'replace', 'default',
                     'via', gateway, 'dev', ipdev])
    if nw_oc.has_key('static-routes'):
        for line in nw_oc['static-routes'].split(','):
            network, masklen, gateway = line.split('/')
            run_command(['/sbin/ip', 'route', 'add',
                         '%s/%s' % (network, masklen), 'via', gateway,
                         'dev', ipdev])

    # Ethtool.
    run_ethtool(ipdev, nw_oc)

    # DHCP.
    if pifrec['ip_configuration_mode'] == "DHCP":
        print
        print "Determining IP information for %s..." % ipdev,
        argv = ['/sbin/dhclient', '-q',
                '-lf', '/var/lib/dhclient/dhclient-%s.leases' % ipdev,
                '-pf', '/var/run/dhclient-%s.pid' % ipdev,
                ipdev]
        if run_command(argv):
            print 'done.'
        else:
            print 'failed.'

def configure_physdev(pif):
    pifrec = db.get_pif_record(pif)
    device = pifrec['device']
    oc = pifrec['other_config']

    run_command(['/sbin/ifconfig', device, 'up'] + mtu_setting(oc))
    run_ethtool(device, oc)

def modify_config(commands):
    run_command(['/root/vswitch/bin/ovs-cfg-mod', '-vANY:console:emer',
                 '-F', '/etc/ovs-vswitchd.conf']
                + commands + ['-c'])
    run_command(['/sbin/service', 'vswitch', 'reload'])

def is_bond_pif(pif):
    pifrec = db.get_pif_record(pif)
    return len(pifrec['bond_master_of']) != 0

def configure_bond(pif):
    pifrec = db.get_pif_record(pif)
    interface = interface_name(pif)
    ipdev = ipdev_name(pif)
    datapath = datapath_name(pif)
    physdev_names = get_physdev_names(pif)

    argv = ['--del-match=bonding.%s.[!0-9]*' % interface]
    argv += ["--add=bonding.%s.slave=%s" % (interface, slave)
             for slave in physdev_names]
    argv += ['--add=bonding.%s.fake-iface=true' % interface]

    if pifrec['MAC'] != "":
        argv += ['--add=port.%s.mac=%s' % (interface, pifrec['MAC'])]

    # Bonding options.
    bond_options = { 
        "mode":   "balance-slb",
        "miimon": "100",
        "downdelay": "200",
        "updelay": "31000",
        "use_carrier": "1",
        }
    # override defaults with values from other-config whose keys
    # being with "bond-"
    oc = pifrec['other_config']
    overrides = filter(lambda (key,val):
                           key.startswith("bond-"), oc.items())
    overrides = map(lambda (key,val): (key[5:], val), overrides)
    bond_options.update(overrides)
    for (name,val) in bond_options.items():
        argv += ["--add=bonding.%s.%s=%s" % (interface, name, val)]
    return argv

def action_up(pif):
    pifrec = db.get_pif_record(pif)

    bridge = bridge_name(pif)
    interface = interface_name(pif)
    ipdev = ipdev_name(pif)
    datapath = datapath_name(pif)
    physdev_pifs = get_physdev_pifs(pif)
    physdev_names = get_physdev_names(pif)
    vlan_slave = None
    if pifrec['VLAN'] != '-1':
        vlan_slave = get_vlan_slave_of_pif(pif)
    if vlan_slave and is_bond_pif(vlan_slave):
        bond_master = vlan_slave
    elif is_bond_pif(pif):
        bond_master = pif
    else:
        bond_master = None
    if bond_master:
        bond_slaves = get_bond_slaves_of_pif(bond_master)
    else:
        bond_slaves = []
    bond_masters = get_bond_masters_of_pif(pif)

    # Support "rpm -e vswitch" gracefully by keeping Centos configuration
    # files up-to-date, even though we don't use them or need them.
    f = configure_pif(pif)
    mode = pifrec['ip_configuration_mode']
    if bridge:
        log("Configuring %s using %s configuration" % (bridge, mode))
        br = open_network_ifcfg(pif)
        configure_network(pif, br)
        br.close()
        f.attach_child(br)
    else:
        log("Configuring %s using %s configuration" % (interface, mode))
        configure_network(pif, f)
    f.close()
    for master in bond_masters:
        master_bridge = bridge_name(master)
        removed = unconfigure_pif(master)
        f.attach_child(removed)
        if master_bridge:
            removed = open_network_ifcfg(master)
            log("Unlinking stale file %s" % removed.path())
            removed.unlink()
            f.attach_child(removed)

    # /etc/xensource/scripts/vif needs to know where to add VIFs.
    if vlan_slave:
        if not os.path.exists(vswitch_config_dir):
            os.mkdir(vswitch_config_dir)
        br = ConfigurationFile("br-%s" % bridge, vswitch_config_dir)
        br.write("VLAN_SLAVE=%s\n" % datapath)
        br.write("VLAN_VID=%s\n" % pifrec['VLAN'])
        br.close()
        f.attach_child(br)

    # Update all configuration files (both ours and Centos's).
    f.apply()
    f.commit()

    # Check the MAC address of each network device and remap if
    # necessary to make names match our expectations.
    for physdev_pif in physdev_pifs:
        remap_pif(physdev_pif)

    # "ifconfig down" the network device and delete its IP address, etc.
    down_netdev(ipdev)
    for physdev_name in physdev_names:
        down_netdev(physdev_name)

    # If we are bringing up a bond, remove IP addresses from the
    # slaves (because we are implicitly being asked to take them down).
    # 
    # Conversely, if we are bringing up an interface that has bond
    # masters, remove IP addresses from the bond master (because we
    # are implicitly being asked to take it down).
    for bond_pif in bond_slaves + bond_masters:
        run_command(["/sbin/ifconfig", ipdev_name(bond_pif), '0.0.0.0']) 

    # Remove all keys related to pif and any bond masters linked to PIF.
    del_ports = [ipdev] + physdev_names + bond_masters
    if vlan_slave and bond_master:
        del_ports += [interface_name(bond_master)]
    
    # What ports do we need to add to the datapath?
    #
    # We definitely need the ipdev, and ordinarily we want the
    # physical devices too, but for bonds we need the bond as bridge
    # port.
    add_ports = [ipdev, datapath]
    if not bond_master:
        add_ports += physdev_names
    else:
        add_ports += [interface_name(bond_master)]

    # What ports do we need to delete?
    #
    #  - All the ports that we add, to avoid duplication and to drop
    #    them from another datapath in case they're misassigned.
    #    
    #  - The physical devices, since they will either be in add_ports
    #    or added to the bonding device (see below).
    #
    #  - The bond masters for pif.  (Ordinarily pif shouldn't have any
    #    bond masters.  If it does then interface-reconfigure is
    #    implicitly being asked to take them down.)
    del_ports = add_ports + physdev_names + bond_masters

    # What networks does this datapath carry?
    #
    # - The network corresponding to the datapath's PIF.
    #
    # - The networks corresponding to any VLANs attached to the
    #   datapath's PIF.
    network_uuids = []
    for nwpif in db.get_pifs_by_record({'device': pifrec['device'],
                                        'host': pifrec['host']}):
        net = db.get_pif_record(nwpif)['network']
        network_uuids += [db.get_network_record(net)['uuid']]

    # Bring up bond slaves early, because ovs-vswitchd initially
    # enables or disables bond slaves based on whether carrier is
    # detected when they are added, and a network device that is down
    # always reports "no carrier".
    bond_slave_physdev_pifs = []
    for slave in bond_slaves:
        bond_slave_physdev_pifs += get_physdev_pifs(slave)
    for slave_physdev_pif in set(bond_slave_physdev_pifs):
        configure_physdev(slave_physdev_pif)

    # Now modify the ovs-vswitchd config file.
    argv = []
    for port in set(del_ports):
        argv += interface_deconfigure_commands(port)
    for port in set(add_ports):
        argv += ['--add=bridge.%s.port=%s' % (datapath, port)]
    if vlan_slave:
        argv += ['--add=vlan.%s.tag=%s' % (ipdev, pifrec['VLAN'])]
        argv += ['--add=iface.%s.internal=true' % (ipdev)]

        # xapi creates a bridge by the name of the ipdev and requires
        # that the IP address will be on it.  We need to delete this
        # bridge because we need that device to be a member of our
        # datapath.
        argv += ['--del-match=bridge.%s.[!0-9]*' % ipdev]

        # xapi insists that its attempts to create the bridge succeed,
        # so force that to happen.
        argv += ['--add=iface.%s.fake-bridge=true' % (ipdev)]
    else:
        try:
            os.unlink("%s/br-%s" % (vswitch_config_dir, bridge))
        except OSError:
            pass
    argv += ['--del-match=bridge.%s.xs-network-uuids=*' % datapath]
    argv += ['--add=bridge.%s.xs-network-uuids=%s' % (datapath, uuid)
             for uuid in set(network_uuids)]
    if bond_master:
        argv += configure_bond(bond_master)
    modify_config(argv)

    # Bring up VLAN slave, plus physical devices other than bond
    # slaves (which we brought up earlier).
    if vlan_slave:
        up_netdev(ipdev_name(vlan_slave))
    for physdev_pif in set(physdev_pifs) - set(bond_slave_physdev_pifs):
        configure_physdev(physdev_pif)

    # Configure network device for local port.
    configure_local_port(pif)

    # Update /etc/issue (which contains the IP address of the management interface)
    os.system("/sbin/update-issue")

    if bond_slaves:
        # There seems to be a race somewhere: without this sleep, using
        # XenCenter to create a bond that becomes the management interface
        # fails with "The underlying connection was closed: A connection that
        # was expected to be kept alive was closed by the server." on every
        # second or third try, even though /var/log/messages doesn't show
        # anything unusual.
        #
        # The race is probably present even without vswitch, but bringing up a
        # bond without vswitch involves a built-in pause of 10 seconds or more
        # to wait for the bond to transition from learning to forwarding state.
        time.sleep(5)
        
def action_down(pif):
    rec = db.get_pif_record(pif)    
    interface = interface_name(pif)
    bridge = bridge_name(pif)
    ipdev = ipdev_name(pif)

    # Support "rpm -e vswitch" gracefully by keeping Centos configuration
    # files up-to-date, even though we don't use them or need them.
    f = unconfigure_pif(pif)
    if bridge:
        br = open_network_ifcfg(pif)
        log("Unlinking stale file %s" % br.path())
        br.unlink()
        f.attach_child(br)
    try:
        f.apply()
        f.commit()
    except Error, e:
        log("action_down failed to apply changes: %s" % e.msg)
        f.revert()
        raise

    argv = []
    if rec['VLAN'] != '-1':
        # Get rid of the VLAN device itself.
        down_netdev(ipdev)
        argv += interface_deconfigure_commands(ipdev)

        # If the VLAN's slave is attached, stop here.
        slave = get_vlan_slave_of_pif(pif)
        if db.get_pif_record(slave)['currently_attached']:
            log("VLAN slave is currently attached")
            modify_config(argv)
            return
        
        # If the VLAN's slave has other VLANs that are attached, stop here.
        masters = get_vlan_masters_of_pif(slave)
        for m in masters:
            if m != pif and db.get_pif_record(m)['currently_attached']:
                log("VLAN slave has other master %s" % interface_naem(m))
                modify_config(argv)
                return

        # Otherwise, take down the VLAN's slave too.
        log("No more masters, bring down vlan slave %s" % interface_name(slave))
        pif = slave
    else:
        # Stop here if this PIF has attached VLAN masters.
        vlan_masters = get_vlan_masters_of_pif(pif)
        log("VLAN masters of %s - %s" % (rec['device'], [interface_name(m) for m in vlan_masters]))
        for m in vlan_masters:
            if db.get_pif_record(m)['currently_attached']:
                log("Leaving %s up due to currently attached VLAN master %s" % (interface, interface_name(m)))
                return

    # pif is now either a bond or a physical device which needs to be
    # brought down.  pif might have changed so re-check all its attributes.
    rec = db.get_pif_record(pif)
    interface = interface_name(pif)
    bridge = bridge_name(pif)
    ipdev = ipdev_name(pif)


    bond_slaves = get_bond_slaves_of_pif(pif)
    log("bond slaves of %s - %s" % (rec['device'], [interface_name(s) for s in bond_slaves]))
    for slave in bond_slaves:
        slave_interface = interface_name(slave)
        log("bring down bond slave %s" % slave_interface)
        argv += interface_deconfigure_commands(slave_interface)
        down_netdev(slave_interface)

    argv += interface_deconfigure_commands(ipdev)
    down_netdev(ipdev)

    argv += ['--del-match', 'bridge.%s.*' % datapath_name(pif)]
    argv += ['--del-match', 'bonding.%s.[!0-9]*' % interface]
    modify_config(argv)

def action_rewrite(pif):
    # Support "rpm -e vswitch" gracefully by keeping Centos configuration
    # files up-to-date, even though we don't use them or need them.
    pifrec = db.get_pif_record(pif)
    f = configure_pif(pif)
    interface = interface_name(pif)
    bridge = bridge_name(pif)
    mode = pifrec['ip_configuration_mode']
    if bridge:
        log("Configuring %s using %s configuration" % (bridge, mode))
        br = open_network_ifcfg(pif)
        configure_network(pif, br)
        br.close()
        f.attach_child(br)
    else:
        log("Configuring %s using %s configuration" % (interface, mode))
        configure_network(pif, f)
    f.close()
    try:
        f.apply()
        f.commit()
    except Error, e:
        log("failed to apply changes: %s" % e.msg)
        f.revert()
        raise

    # We have no code of our own to run here.
    pass

def main(argv=None):
    global output_directory, management_pif
    
    session = None
    pif_uuid = None
    pif = None

    force_interface = None
    force_management = False
    
    if argv is None:
        argv = sys.argv

    try:
        try:
            shortops = "h"
            longops = [ "output-directory=",
                        "pif=", "pif-uuid=",
                        "session=",
                        "force=",
                        "force-interface=",
                        "management",
                        "test-mode",
                        "device=", "mode=", "ip=", "netmask=", "gateway=",
                        "help" ]
            arglist, args = getopt.gnu_getopt(argv[1:], shortops, longops)
        except getopt.GetoptError, msg:
            raise Usage(msg)

        force_rewrite_config = {}
        
        for o,a in arglist:
            if o == "--output-directory":
                output_directory = a
            elif o == "--pif":
                pif = a
            elif o == "--pif-uuid":
                pif_uuid = a
            elif o == "--session":
                session = a
            elif o == "--force-interface" or o == "--force":
                force_interface = a
            elif o == "--management":
                force_management = True
            elif o in ["--device", "--mode", "--ip", "--netmask", "--gateway"]:
                force_rewrite_config[o[2:]] = a
            elif o == "-h" or o == "--help":
                print __doc__ % {'command-name': os.path.basename(argv[0])}
                return 0

        if not debug_mode():
            syslog.openlog(os.path.basename(argv[0]))
            log("Called as " + str.join(" ", argv))
        if len(args) < 1:
            raise Usage("Required option <action> not present")
        if len(args) > 1:
            raise Usage("Too many arguments")

        action = args[0]
        # backwards compatibility
        if action == "rewrite-configuration": action = "rewrite"
        
        if output_directory and ( session or pif ):
            raise Usage("--session/--pif cannot be used with --output-directory")
        if ( session or pif ) and pif_uuid:
            raise Usage("--session/--pif and --pif-uuid are mutually exclusive.")
        if ( session and not pif ) or ( not session and pif ):
            raise Usage("--session and --pif must be used together.")
        if force_interface and ( session or pif or pif_uuid ):
            raise Usage("--force is mutually exclusive with --session, --pif and --pif-uuid")
        if len(force_rewrite_config) and not (force_interface and action == "rewrite"):
            raise Usage("\"--force rewrite\" needed for --device, --mode, --ip, --netmask, and --gateway")

        global db
        if force_interface:
            log("Force interface %s %s" % (force_interface, action))

            if action == "rewrite":
                action_force_rewrite(force_interface, force_rewrite_config)
            else:
                db = DatabaseCache(cache_file=dbcache_file)
                host = db.extras['host']
                pif = db.get_pif_by_bridge(host, force_interface)
                management_pif = db.get_management_pif(host)

                if action == "up":
                    action_up(pif)
                elif action == "down":
                    action_down(pif)
                else:
                    raise Usage("Unknown action %s"  % action)
        else:
            db = DatabaseCache(session_ref=session)

            if pif_uuid:
                pif = db.get_pif_by_uuid(pif_uuid)
        
            if not pif:
                raise Usage("No PIF given")

            if force_management:
                # pif is going to be the management pif 
                management_pif = pif
            else:
                # pif is not going to be the management pif.
                # Search DB cache for pif on same host with management=true
                pifrec = db.get_pif_record(pif)
                host = pifrec['host']
                management_pif = db.get_management_pif(host)

            log_pif_action(action, pif)

            if not check_allowed(pif):
                return 0

            if action == "up":
                action_up(pif)
            elif action == "down":
                action_down(pif)
            elif action == "rewrite":
                action_rewrite(pif)
            else:
                raise Usage("Unknown action %s"  % action)

            # Save cache.
            pifrec = db.get_pif_record(pif)
            db.save(dbcache_file, {'host': pifrec['host']})
        
    except Usage, err:
        print >>sys.stderr, err.msg
        print >>sys.stderr, "For help use --help."
        return 2
    except Error, err:
        log(err.msg)
        return 1
    
    return 0
\f
# The following code allows interface-reconfigure to keep Centos
# network configuration files up-to-date, even though the vswitch
# never uses them.  In turn, that means that "rpm -e vswitch" does not
# have to update any configuration files.

def configure_ethtool(oc, f):
    # Options for "ethtool -s"
    settings = None
    setting_opts = ["autoneg", "speed", "duplex"]
    # Options for "ethtool -K"
    offload = None
    offload_opts = ["rx", "tx", "sg", "tso", "ufo", "gso"]
    
    for opt in [opt for opt in setting_opts + offload_opts if oc.has_key("ethtool-" + opt)]:
        val = oc["ethtool-" + opt]

        if opt in ["speed"]:
            if val in ["10", "100", "1000"]:
                val = "speed " + val
            else:
                log("Invalid value for ethtool-speed = %s. Must be 10|100|1000." % val)
                val = None
        elif opt in ["duplex"]:
            if val in ["half", "full"]:
                val = "duplex " + val
            else:
                log("Invalid value for ethtool-duplex = %s. Must be half|full." % val)
                val = None
        elif opt in ["autoneg"] + offload_opts:
            if val in ["true", "on"]:
                val = opt + " on"
            elif val in ["false", "off"]:
                val = opt + " off"
            else:
                log("Invalid value for ethtool-%s = %s. Must be on|true|off|false." % (opt, val))
                val = None

        if opt in setting_opts:
            if val and settings:
                settings = settings + " " + val
            else:
                settings = val
        elif opt in offload_opts:
            if val and offload:
                offload = offload + " " + val
            else:
                offload = val

    if settings:
        f.write("ETHTOOL_OPTS=\"%s\"\n" % settings)
    if offload:
        f.write("ETHTOOL_OFFLOAD_OPTS=\"%s\"\n" % offload)

def configure_mtu(oc, f):
    if not oc.has_key('mtu'):
        return
    
    try:
        mtu = int(oc['mtu'])
        f.write("MTU=%d\n" % mtu)
    except ValueError, x:
        log("Invalid value for mtu = %s" % mtu)

def configure_static_routes(interface, oc, f):
    """Open a route-<interface> file for static routes.
    
    Opens the static routes configuration file for interface and writes one
    line for each route specified in the network's other config "static-routes" value.
    E.g. if
           interface ( RO): xenbr1
           other-config (MRW): static-routes: 172.16.0.0/15/192.168.0.3,172.18.0.0/16/192.168.0.4;...

    Then route-xenbr1 should be
          172.16.0.0/15 via 192.168.0.3 dev xenbr1
          172.18.0.0/16 via 192.168.0.4 dev xenbr1
    """
    fname = "route-%s" % interface
    if oc.has_key('static-routes'):
        # The key is present - extract comma seperates entries
        lines = oc['static-routes'].split(',')
    else:
        # The key is not present, i.e. there are no static routes
        lines = []

    child = ConfigurationFile(fname)
    child.write("# DO NOT EDIT: This file (%s) was autogenerated by %s\n" % \
            (os.path.basename(child.path()), os.path.basename(sys.argv[0])))

    try:
        for l in lines:
            network, masklen, gateway = l.split('/')
            child.write("%s/%s via %s dev %s\n" % (network, masklen, gateway, interface))
            
        f.attach_child(child)
        child.close()

    except ValueError, e:
        log("Error in other-config['static-routes'] format for network %s: %s" % (interface, e))

def __open_ifcfg(interface):
    """Open a network interface configuration file.

    Opens the configuration file for interface, writes a header and
    common options and returns the file object.
    """
    fname = "ifcfg-%s" % interface
    f = ConfigurationFile(fname)
    
    f.write("# DO NOT EDIT: This file (%s) was autogenerated by %s\n" % \
            (os.path.basename(f.path()), os.path.basename(sys.argv[0])))
    f.write("XEMANAGED=yes\n")
    f.write("DEVICE=%s\n" % interface)
    f.write("ONBOOT=no\n")
    
    return f

def open_network_ifcfg(pif):    
    bridge = bridge_name(pif)
    interface = interface_name(pif)
    if bridge:
        return __open_ifcfg(bridge)
    else:
        return __open_ifcfg(interface)


def open_pif_ifcfg(pif):
    pifrec = db.get_pif_record(pif)
    
    log("Configuring %s (%s)" % (interface_name(pif), pifrec['MAC']))
    
    f = __open_ifcfg(interface_name(pif))

    if pifrec.has_key('other_config'):
        configure_ethtool(pifrec['other_config'], f)
        configure_mtu(pifrec['other_config'], f)

    return f

def configure_network(pif, f):
    """Write the configuration file for a network.

    Writes configuration derived from the network object into the relevant 
    ifcfg file.  The configuration file is passed in, but if the network is 
    bridgeless it will be ifcfg-<interface>, otherwise it will be ifcfg-<bridge>.

    This routine may also write ifcfg files of the networks corresponding to other PIFs
    in order to maintain consistency.

    params:
        pif:  Opaque_ref of pif
        f :   ConfigurationFile(/path/to/ifcfg) to which we append network configuration
    """
    
    pifrec = db.get_pif_record(pif)
    host = pifrec['host']
    nw = pifrec['network']
    nwrec = db.get_network_record(nw)
    oc = None
    bridge = bridge_name(pif)
    interface = interface_name(pif)
    if bridge:
        device = bridge
    else:
        device = interface

    if nwrec.has_key('other_config'):
        configure_ethtool(nwrec['other_config'], f)
        configure_mtu(nwrec['other_config'], f)
        configure_static_routes(device, nwrec['other_config'], f)

    
    if pifrec.has_key('other_config'):
        oc = pifrec['other_config']

    if device == bridge:
        f.write("TYPE=Bridge\n")
        f.write("DELAY=0\n")
        f.write("STP=off\n")
        f.write("PIFDEV=%s\n" % interface_name(pif))

    if pifrec['ip_configuration_mode'] == "DHCP":
        f.write("BOOTPROTO=dhcp\n")
        f.write("PERSISTENT_DHCLIENT=yes\n")
    elif pifrec['ip_configuration_mode'] == "Static":
        f.write("BOOTPROTO=none\n") 
        f.write("NETMASK=%(netmask)s\n" % pifrec)
        f.write("IPADDR=%(IP)s\n" % pifrec)
        f.write("GATEWAY=%(gateway)s\n" % pifrec)
    elif pifrec['ip_configuration_mode'] == "None":
        f.write("BOOTPROTO=none\n")
    else:
        raise Error("Unknown ip-configuration-mode %s" % pifrec['ip_configuration_mode'])

    if pifrec.has_key('DNS') and pifrec['DNS'] != "":
        ServerList = pifrec['DNS'].split(",")
        for i in range(len(ServerList)): f.write("DNS%d=%s\n" % (i+1, ServerList[i]))
    if oc and oc.has_key('domain'):
        f.write("DOMAIN='%s'\n" % oc['domain'].replace(',', ' '))

    # We only allow one ifcfg-xenbr* to have PEERDNS=yes and there can be only one GATEWAYDEV in /etc/sysconfig/network.
    # The peerdns pif will be the one with pif::other-config:peerdns=true, or the mgmt pif if none have this set.
    # The gateway pif will be the one with pif::other-config:defaultroute=true, or the mgmt pif if none have this set.

    # Work out which pif on this host should be the one with PEERDNS=yes and which should be the GATEWAYDEV
    #
    # Note: we prune out the bond master pif (if it exists).
    # This is because when we are called to bring up an interface with a bond master, it is implicit that
    # we should bring down that master.
    pifs_on_host = [ __pif for __pif in db.get_all_pifs() if
                     db.get_pif_record(__pif)['host'] == host and 
                     (not  __pif in get_bond_masters_of_pif(pif)) ]
    other_pifs_on_host = [ __pif for __pif in pifs_on_host if __pif != pif ]

    peerdns_pif = None
    defaultroute_pif = None
    
    # loop through all the pifs on this host looking for one with
    #   other-config:peerdns = true, and one with
    #   other-config:default-route=true
    for __pif in pifs_on_host:
        __pifrec = db.get_pif_record(__pif)
        __oc = __pifrec['other_config']
        if __oc.has_key('peerdns') and __oc['peerdns'] == 'true':
            if peerdns_pif == None:
                peerdns_pif = __pif
            else:
                log('Warning: multiple pifs with "peerdns=true" - choosing %s and ignoring %s' % \
                        (db.get_pif_record(peerdns_pif)['device'], __pifrec['device']))
        if __oc.has_key('defaultroute') and __oc['defaultroute'] == 'true':
            if defaultroute_pif == None:
                defaultroute_pif = __pif
            else:
                log('Warning: multiple pifs with "defaultroute=true" - choosing %s and ignoring %s' % \
                        (db.get_pif_record(defaultroute_pif)['device'], __pifrec['device']))
    
    # If no pif is explicitly specified then use the mgmt pif for peerdns/defaultroute
    if peerdns_pif == None:
        peerdns_pif = management_pif
    if defaultroute_pif == None:
        defaultroute_pif = management_pif
        
    # Update all the other network's ifcfg files and ensure consistency
    for __pif in other_pifs_on_host:
        __f = open_network_ifcfg(__pif)
        peerdns_line_wanted = 'PEERDNS=%s\n' % ((__pif == peerdns_pif) and 'yes' or 'no')
        lines =  __f.readlines()

        if not peerdns_line_wanted in lines:
            # the PIF selected for DNS has changed and as a result this ifcfg file needs rewriting
            for line in lines:
                if not line.lstrip().startswith('PEERDNS'):
                    __f.write(line)
            log("Setting %s in %s" % (peerdns_line_wanted.strip(), __f.path()))
            __f.write(peerdns_line_wanted)
            __f.close()
            f.attach_child(__f)

        else:
            # There is no need to change this ifcfg file.  So don't attach_child.
            pass
        
    # ... and for this pif too
    f.write('PEERDNS=%s\n' % ((pif == peerdns_pif) and 'yes' or 'no'))
    
    # Update gatewaydev
    fnetwork = ConfigurationFile("network", "/etc/sysconfig")
    for line in fnetwork.readlines():
        if line.lstrip().startswith('GATEWAY') :
            continue
        fnetwork.write(line)
    if defaultroute_pif:
        gatewaydev = bridge_name(defaultroute_pif)
        if not gatewaydev:
            gatewaydev = interface_name(defaultroute_pif)
        fnetwork.write('GATEWAYDEV=%s\n' % gatewaydev)
    fnetwork.close()
    f.attach_child(fnetwork)

    return


def configure_physical_interface(pif):
    """Write the configuration for a physical interface.

    Writes the configuration file for the physical interface described by
    the pif object.

    Returns the open file handle for the interface configuration file.
    """

    pifrec = db.get_pif_record(pif)

    f = open_pif_ifcfg(pif)
    
    f.write("TYPE=Ethernet\n")
    f.write("HWADDR=%(MAC)s\n" % pifrec)

    return f

def configure_bond_interface(pif):
    """Write the configuration for a bond interface.

    Writes the configuration file for the bond interface described by
    the pif object. Handles writing the configuration for the slave
    interfaces.

    Returns the open file handle for the bond interface configuration
    file.
    """

    pifrec = db.get_pif_record(pif)
    oc = pifrec['other_config']
    f = open_pif_ifcfg(pif)

    if pifrec['MAC'] != "":
        f.write("MACADDR=%s\n" % pifrec['MAC'])

    for slave in get_bond_slaves_of_pif(pif):
        s = configure_physical_interface(slave)
        s.write("MASTER=%(device)s\n" % pifrec)
        s.write("SLAVE=yes\n")
        s.close()
        f.attach_child(s)

    # The bond option defaults
    bond_options = { 
        "mode":   "balance-slb",
        "miimon": "100",
        "downdelay": "200",
        "updelay": "31000",
        "use_carrier": "1",
        }

    # override defaults with values from other-config whose keys being with "bond-"
    overrides = filter(lambda (key,val): key.startswith("bond-"), oc.items())
    overrides = map(lambda (key,val): (key[5:], val), overrides)
    bond_options.update(overrides)

    # write the bond options to ifcfg-bondX
    f.write('BONDING_OPTS="')
    for (name,val) in bond_options.items():
        f.write("%s=%s " % (name,val))
    f.write('"\n')
    return f

def configure_vlan_interface(pif):
    """Write the configuration for a VLAN interface.

    Writes the configuration file for the VLAN interface described by
    the pif object. Handles writing the configuration for the master
    interface if necessary.

    Returns the open file handle for the VLAN interface configuration
    file.
    """

    slave = configure_pif(get_vlan_slave_of_pif(pif))
    slave.close()

    f = open_pif_ifcfg(pif)
    f.write("VLAN=yes\n")
    f.attach_child(slave)
    
    return f

def configure_pif(pif):
    """Write the configuration for a PIF object.

    Writes the configuration file the PIF and all dependent
    interfaces (bond slaves and VLAN masters etc).

    Returns the open file handle for the interface configuration file.
    """

    pifrec = db.get_pif_record(pif)

    if pifrec['VLAN'] != '-1':
        f = configure_vlan_interface(pif)
    elif len(pifrec['bond_master_of']) != 0:
        f = configure_bond_interface(pif)
    else:
        f = configure_physical_interface(pif)

    bridge = bridge_name(pif)
    if bridge:
        f.write("BRIDGE=%s\n" % bridge)

    return f

def unconfigure_pif(pif):
    """Clear up the files created by configure_pif"""
    f = open_pif_ifcfg(pif)
    log("Unlinking stale file %s" % f.path())
    f.unlink()
    return f
\f
if __name__ == "__main__":
    rc = 1
    try:
        rc = main()
    except:
        ex = sys.exc_info()
        err = traceback.format_exception(*ex)
        for exline in err:
            log(exline)

    if not debug_mode():
        syslog.closelog()
        
    sys.exit(rc)