# Copyright 2012 OpenStack Foundation
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

import os
import re

import debtcollector
import eventlet
import netaddr
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import excutils
import six

from neutron._i18n import _, _LE
from neutron.agent.common import utils
from neutron.common import constants
from neutron.common import exceptions

LOG = logging.getLogger(__name__)

OPTS = [
    cfg.BoolOpt('ip_lib_force_root',
                default=False,
                help=_('Force ip_lib calls to use the root helper')),
]


LOOPBACK_DEVNAME = 'lo'

IP_NETNS_PATH = '/var/run/netns'
SYS_NET_PATH = '/sys/class/net'
DEFAULT_GW_PATTERN = re.compile(r"via (\S+)")
METRIC_PATTERN = re.compile(r"metric (\S+)")
DEVICE_NAME_PATTERN = re.compile(r"(\d+?): (\S+?):.*")


def remove_interface_suffix(interface):
    """Remove a possible "<if>@<endpoint>" suffix from an interface' name.

    This suffix can appear in some kernel versions, and intends on specifying,
    for example, a veth's pair. However, this interface name is useless to us
    as further 'ip' commands require that the suffix be removed.
    """
    # If '@' is not present, this will do nothing.
    return interface.partition("@")[0]


class AddressNotReady(exceptions.NeutronException):
    message = _("Failure waiting for address %(address)s to "
                "become ready: %(reason)s")


class SubProcessBase(object):
    def __init__(self, namespace=None,
                 log_fail_as_error=True):
        self.namespace = namespace
        self.log_fail_as_error = log_fail_as_error
        try:
            self.force_root = cfg.CONF.ip_lib_force_root
        except cfg.NoSuchOptError:
            # Only callers that need to force use of the root helper
            # need to register the option.
            self.force_root = False

    def _run(self, options, command, args):
        if self.namespace:
            return self._as_root(options, command, args)
        elif self.force_root:
            # Force use of the root helper to ensure that commands
            # will execute in dom0 when running under XenServer/XCP.
            return self._execute(options, command, args, run_as_root=True,
                                 log_fail_as_error=self.log_fail_as_error)
        else:
            return self._execute(options, command, args,
                                 log_fail_as_error=self.log_fail_as_error)

    def _as_root(self, options, command, args, use_root_namespace=False):
        namespace = self.namespace if not use_root_namespace else None

        return self._execute(options, command, args, run_as_root=True,
                             namespace=namespace,
                             log_fail_as_error=self.log_fail_as_error)

    @classmethod
    def _execute(cls, options, command, args, run_as_root=False,
                 namespace=None, log_fail_as_error=True):
        opt_list = ['-%s' % o for o in options]
        ip_cmd = add_namespace_to_cmd(['ip'], namespace)
        cmd = ip_cmd + opt_list + [command] + list(args)
        return utils.execute(cmd, run_as_root=run_as_root,
                             log_fail_as_error=log_fail_as_error)

    def set_log_fail_as_error(self, fail_with_error):
        self.log_fail_as_error = fail_with_error

    def get_log_fail_as_error(self):
        return self.log_fail_as_error


class IPWrapper(SubProcessBase):
    def __init__(self, namespace=None):
        super(IPWrapper, self).__init__(namespace=namespace)
        self.netns = IpNetnsCommand(self)

    def device(self, name):
        return IPDevice(name, namespace=self.namespace)

    def get_devices(self, exclude_loopback=False):
        retval = []
        if self.namespace:
            # we call out manually because in order to avoid screen scraping
            # iproute2 we use find to see what is in the sysfs directory, as
            # suggested by Stephen Hemminger (iproute2 dev).
            output = utils.execute(['ip', 'netns', 'exec', self.namespace,
                                    'find', SYS_NET_PATH, '-maxdepth', '1',
                                    '-type', 'l', '-printf', '%f '],
                                   run_as_root=True,
                                   log_fail_as_error=self.log_fail_as_error
                                   ).split()
        else:
            output = (
                i for i in os.listdir(SYS_NET_PATH)
                if os.path.islink(os.path.join(SYS_NET_PATH, i))
            )

        for name in output:
            if exclude_loopback and name == LOOPBACK_DEVNAME:
                continue
            retval.append(IPDevice(name, namespace=self.namespace))

        return retval

    def get_device_by_ip(self, ip):
        """Get the IPDevice from system which has ip configured.

        @param ip: look for the device holding this ip. If this is None,
                   None is returned.
        @type ip: str.
        """
        if not ip:
            return None

        addr = IpAddrCommand(self)
        devices = addr.get_devices_with_ip(to=ip)
        if devices:
            return IPDevice(devices[0]['name'], namespace=self.namespace)

    def add_tuntap(self, name, mode='tap'):
        self._as_root([], 'tuntap', ('add', name, 'mode', mode))
        return IPDevice(name, namespace=self.namespace)

    def add_veth(self, name1, name2, namespace2=None):
        args = ['add', name1, 'type', 'veth', 'peer', 'name', name2]

        if namespace2 is None:
            namespace2 = self.namespace
        else:
            self.ensure_namespace(namespace2)
            args += ['netns', namespace2]

        self._as_root([], 'link', tuple(args))

        return (IPDevice(name1, namespace=self.namespace),
                IPDevice(name2, namespace=namespace2))

    def add_macvtap(self, name, src_dev, mode='bridge'):
        args = ['add', 'link', src_dev, 'name', name, 'type', 'macvtap',
                'mode', mode]
        self._as_root([], 'link', tuple(args))
        return IPDevice(name, namespace=self.namespace)

    def del_veth(self, name):
        """Delete a virtual interface between two namespaces."""
        self._as_root([], 'link', ('del', name))

    def add_dummy(self, name):
        """Create a Linux dummy interface with the given name."""
        self._as_root([], 'link', ('add', name, 'type', 'dummy'))
        return IPDevice(name, namespace=self.namespace)

    def ensure_namespace(self, name):
        if not self.netns.exists(name):
            ip = self.netns.add(name)
            lo = ip.device(LOOPBACK_DEVNAME)
            lo.link.set_up()
        else:
            ip = IPWrapper(namespace=name)
        return ip

    def namespace_is_empty(self):
        return not self.get_devices(exclude_loopback=True)

    def garbage_collect_namespace(self):
        """Conditionally destroy the namespace if it is empty."""
        if self.namespace and self.netns.exists(self.namespace):
            if self.namespace_is_empty():
                self.netns.delete(self.namespace)
                return True
        return False

    def add_device_to_namespace(self, device):
        if self.namespace:
            device.link.set_netns(self.namespace)

    def add_vlan(self, name, physical_interface, vlan_id):
        cmd = ['add', 'link', physical_interface, 'name', name,
               'type', 'vlan', 'id', vlan_id]
        self._as_root([], 'link', cmd)
        return IPDevice(name, namespace=self.namespace)

    def add_vxlan(self, name, vni, group=None, dev=None, ttl=None, tos=None,
                  local=None, port=None, proxy=False):
        cmd = ['add', name, 'type', 'vxlan', 'id', vni]
        if group:
            cmd.extend(['group', group])
        if dev:
            cmd.extend(['dev', dev])
        if ttl:
            cmd.extend(['ttl', ttl])
        if tos:
            cmd.extend(['tos', tos])
        if local:
            cmd.extend(['local', local])
        if proxy:
            cmd.append('proxy')
        # tuple: min,max
        if port and len(port) == 2:
            cmd.extend(['port', port[0], port[1]])
        elif port:
            raise exceptions.NetworkVxlanPortRangeError(vxlan_range=port)
        self._as_root([], 'link', cmd)
        return (IPDevice(name, namespace=self.namespace))

    @classmethod
    def get_namespaces(cls):
        if not cfg.CONF.AGENT.use_helper_for_ns_read:
            return os.listdir(IP_NETNS_PATH)

        output = cls._execute([], 'netns', ['list'], run_as_root=True)
        return [l.split()[0] for l in output.splitlines()]


class IPDevice(SubProcessBase):
    def __init__(self, name, namespace=None):
        super(IPDevice, self).__init__(namespace=namespace)
        self.name = name
        self.link = IpLinkCommand(self)
        self.addr = IpAddrCommand(self)
        self.route = IpRouteCommand(self)
        self.neigh = IpNeighCommand(self)

    def __eq__(self, other):
        return (other is not None and self.name == other.name
                and self.namespace == other.namespace)

    def __str__(self):
        return self.name

    def exists(self):
        """Return True if the device exists in the namespace."""
        # we must save and restore this before returning
        orig_log_fail_as_error = self.get_log_fail_as_error()
        self.set_log_fail_as_error(False)
        try:
            return bool(self.link.address)
        except RuntimeError:
            return False
        finally:
            self.set_log_fail_as_error(orig_log_fail_as_error)

    def delete_addr_and_conntrack_state(self, cidr):
        """Delete an address along with its conntrack state

        This terminates any active connections through an IP.

        :param cidr: the IP address for which state should be removed.
            This can be passed as a string with or without /NN.
            A netaddr.IPAddress or netaddr.Network representing the IP address
            can also be passed.
        """
        self.addr.delete(cidr)

        ip_str = str(netaddr.IPNetwork(cidr).ip)
        ip_wrapper = IPWrapper(namespace=self.namespace)

        # Delete conntrack state for ingress traffic
        # If 0 flow entries have been deleted
        # conntrack -D will return 1
        try:
            ip_wrapper.netns.execute(["conntrack", "-D", "-d", ip_str],
                                     check_exit_code=True,
                                     extra_ok_codes=[1])

        except RuntimeError:
            LOG.exception(_LE("Failed deleting ingress connection state of"
                              " floatingip %s"), ip_str)

        # Delete conntrack state for egress traffic
        try:
            ip_wrapper.netns.execute(["conntrack", "-D", "-q", ip_str],
                                     check_exit_code=True,
                                     extra_ok_codes=[1])
        except RuntimeError:
            LOG.exception(_LE("Failed deleting egress connection state of"
                              " floatingip %s"), ip_str)

    def _sysctl(self, cmd):
        """execute() doesn't return the exit status of the command it runs,
        it returns stdout and stderr. Setting check_exit_code=True will cause
        it to raise a RuntimeError if the exit status of the command is
        non-zero, which in sysctl's case is an error. So we're normalizing
        that into zero (success) and one (failure) here to mimic what
        "echo $?" in a shell would be.

        This is all because sysctl is too verbose and prints the value you
        just set on success, unlike most other utilities that print nothing.

        execute() will have dumped a message to the logs with the actual
        output on failure, so it's not lost, and we don't need to print it
        here.
        """
        cmd = ['sysctl', '-w'] + cmd
        ip_wrapper = IPWrapper(self.namespace)
        try:
            ip_wrapper.netns.execute(cmd, run_as_root=True,
                                     check_exit_code=True)
        except RuntimeError:
            LOG.exception(_LE("Failed running %s"), cmd)
            return 1

        return 0

    def disable_ipv6(self):
        sysctl_name = re.sub(r'\.', '/', self.name)
        cmd = 'net.ipv6.conf.%s.disable_ipv6=1' % sysctl_name
        return self._sysctl([cmd])


class IpCommandBase(object):
    COMMAND = ''

    def __init__(self, parent):
        self._parent = parent

    def _run(self, options, args):
        return self._parent._run(options, self.COMMAND, args)

    def _as_root(self, options, args, use_root_namespace=False):
        return self._parent._as_root(options,
                                     self.COMMAND,
                                     args,
                                     use_root_namespace=use_root_namespace)


class IPRule(SubProcessBase):
    def __init__(self, namespace=None):
        super(IPRule, self).__init__(namespace=namespace)
        self.rule = IpRuleCommand(self)


class IpRuleCommand(IpCommandBase):
    COMMAND = 'rule'

    @staticmethod
    def _make_canonical(ip_version, settings):
        """Converts settings to a canonical representation to compare easily"""
        def canonicalize_fwmark_string(fwmark_mask):
            """Reformats fwmark/mask in to a canonical form

            Examples, these are all equivalent:
                "0x1"
                0x1
                "0x1/0xfffffffff"
                (0x1, 0xfffffffff)

            :param fwmark_mask: The firewall and mask (default 0xffffffff)
            :type fwmark_mask: A string with / as delimiter, an iterable, or a
                single value.
            """
            # Turn the value we were passed in to an iterable: fwmark[, mask]
            if isinstance(fwmark_mask, six.string_types):
                # A / separates the optional mask in a string
                iterable = fwmark_mask.split('/')
            else:
                try:
                    iterable = iter(fwmark_mask)
                except TypeError:
                    # At this point, it must be a single integer
                    iterable = [fwmark_mask]

            def to_i(s):
                if isinstance(s, six.string_types):
                    # Passing 0 as "base" arg to "int" causes it to determine
                    # the base automatically.
                    return int(s, 0)
                # s isn't a string, can't specify base argument
                return int(s)

            integers = [to_i(x) for x in iterable]

            # The default mask is all ones, the mask is 32 bits.
            if len(integers) == 1:
                integers.append(0xffffffff)

            # We now have two integers in a list.  Convert to canonical string.
            return '{0:#x}/{1:#x}'.format(*integers)

        def canonicalize(item):
            k, v = item
            # ip rule shows these as 'any'
            if k == 'from' and v == 'all':
                return k, constants.IP_ANY[ip_version]
            # lookup and table are interchangeable.  Use table every time.
            if k == 'lookup':
                return 'table', v
            if k == 'fwmark':
                return k, canonicalize_fwmark_string(v)
            return k, v

        if 'type' not in settings:
            settings['type'] = 'unicast'

        return {k: str(v) for k, v in map(canonicalize, settings.items())}

    def _parse_line(self, ip_version, line):
        # Typical rules from 'ip rule show':
        # 4030201:  from 1.2.3.4/24 lookup 10203040
        # 1024:     from all iif qg-c43b1928-48 lookup noscope

        parts = line.split()
        if not parts:
            return {}

        # Format of line is: "priority: <key> <value> ... [<type>]"
        settings = {k: v for k, v in zip(parts[1::2], parts[2::2])}
        settings['priority'] = parts[0][:-1]
        if len(parts) % 2 == 0:
            # When line has an even number of columns, last one is the type.
            settings['type'] = parts[-1]

        return self._make_canonical(ip_version, settings)

    def list_rules(self, ip_version):
        lines = self._as_root([ip_version], ['show']).splitlines()
        return [self._parse_line(ip_version, line) for line in lines]

    def _exists(self, ip_version, **kwargs):
        return kwargs in self.list_rules(ip_version)

    def _make__flat_args_tuple(self, *args, **kwargs):
        for kwargs_item in sorted(kwargs.items(), key=lambda i: i[0]):
            args += kwargs_item
        return tuple(args)

    def add(self, ip, **kwargs):
        ip_version = get_ip_version(ip)

        kwargs.update({'from': ip})
        canonical_kwargs = self._make_canonical(ip_version, kwargs)

        if not self._exists(ip_version, **canonical_kwargs):
            args_tuple = self._make__flat_args_tuple('add', **canonical_kwargs)
            self._as_root([ip_version], args_tuple)

    def delete(self, ip, **kwargs):
        ip_version = get_ip_version(ip)

        # TODO(Carl) ip ignored in delete, okay in general?

        canonical_kwargs = self._make_canonical(ip_version, kwargs)

        args_tuple = self._make__flat_args_tuple('del', **canonical_kwargs)
        self._as_root([ip_version], args_tuple)


class IpDeviceCommandBase(IpCommandBase):
    @property
    def name(self):
        return self._parent.name


class IpLinkCommand(IpDeviceCommandBase):
    COMMAND = 'link'

    def set_address(self, mac_address):
        self._as_root([], ('set', self.name, 'address', mac_address))

    def set_allmulticast_on(self):
        self._as_root([], ('set', self.name, 'allmulticast', 'on'))

    def set_mtu(self, mtu_size):
        self._as_root([], ('set', self.name, 'mtu', mtu_size))

    def set_up(self):
        return self._as_root([], ('set', self.name, 'up'))

    def set_down(self):
        return self._as_root([], ('set', self.name, 'down'))

    def set_netns(self, namespace):
        self._as_root([], ('set', self.name, 'netns', namespace))
        self._parent.namespace = namespace

    def set_name(self, name):
        self._as_root([], ('set', self.name, 'name', name))
        self._parent.name = name

    def set_alias(self, alias_name):
        self._as_root([], ('set', self.name, 'alias', alias_name))

    def delete(self):
        self._as_root([], ('delete', self.name))

    @property
    def address(self):
        return self.attributes.get('link/ether')

    @property
    def state(self):
        return self.attributes.get('state')

    @property
    def mtu(self):
        return self.attributes.get('mtu')

    @property
    def qdisc(self):
        return self.attributes.get('qdisc')

    @property
    def qlen(self):
        return self.attributes.get('qlen')

    @property
    def alias(self):
        return self.attributes.get('alias')

    @property
    def attributes(self):
        return self._parse_line(self._run(['o'], ('show', self.name)))

    def _parse_line(self, value):
        if not value:
            return {}

        device_name, settings = value.replace("\\", '').split('>', 1)
        tokens = settings.split()
        keys = tokens[::2]
        values = [int(v) if v.isdigit() else v for v in tokens[1::2]]

        retval = dict(zip(keys, values))
        return retval


class IpAddrCommand(IpDeviceCommandBase):
    COMMAND = 'addr'

    def add(self, cidr, scope='global'):
        net = netaddr.IPNetwork(cidr)
        args = ['add', cidr,
                'scope', scope,
                'dev', self.name]
        if net.version == 4:
            args += ['brd', str(net[-1])]
        self._as_root([net.version], tuple(args))

    def delete(self, cidr):
        ip_version = get_ip_version(cidr)
        self._as_root([ip_version],
                      ('del', cidr,
                       'dev', self.name))

    def flush(self, ip_version):
        self._as_root([ip_version], ('flush', self.name))

    def get_devices_with_ip(self, name=None, scope=None, to=None,
                            filters=None, ip_version=None):
        """Get a list of all the devices with an IP attached in the namespace.

        @param name: if it's not None, only a device with that matching name
                     will be returned.
        """
        options = [ip_version] if ip_version else []

        args = ['show']
        if name:
            args += [name]
        if filters:
            args += filters
        if scope:
            args += ['scope', scope]
        if to:
            args += ['to', to]

        retval = []

        for line in self._run(options, tuple(args)).split('\n'):
            line = line.strip()

            match = DEVICE_NAME_PATTERN.search(line)
            if match:
                # Found a match for a device name, but its' addresses will
                # only appear in following lines, so we may as well continue.
                device_name = remove_interface_suffix(match.group(2))
                continue
            elif not line.startswith('inet'):
                continue

            parts = line.split(" ")
            if parts[0] == 'inet6':
                scope = parts[3]
            else:
                if parts[2] == 'brd':
                    scope = parts[5]
                else:
                    scope = parts[3]

            retval.append(dict(name=device_name,
                               cidr=parts[1],
                               scope=scope,
                               dynamic=('dynamic' == parts[-1]),
                               tentative=('tentative' in line),
                               dadfailed=('dadfailed' == parts[-1])))
        return retval

    def list(self, scope=None, to=None, filters=None, ip_version=None):
        """Get device details of a device named <self.name>."""
        return self.get_devices_with_ip(
            self.name, scope, to, filters, ip_version)

    def wait_until_address_ready(self, address, wait_time=30):
        """Wait until an address is no longer marked 'tentative'

        raises AddressNotReady if times out or address not present on interface
        """
        def is_address_ready():
            try:
                addr_info = self.list(to=address)[0]
            except IndexError:
                raise AddressNotReady(
                    address=address,
                    reason=_('Address not present on interface'))
            if not addr_info['tentative']:
                return True
            if addr_info['dadfailed']:
                raise AddressNotReady(
                    address=address, reason=_('Duplicate address detected'))
        errmsg = _("Exceeded %s second limit waiting for "
                   "address to leave the tentative state.") % wait_time
        utils.utils.wait_until_true(
            is_address_ready, timeout=wait_time, sleep=0.20,
            exception=AddressNotReady(address=address, reason=errmsg))


class IpRouteCommand(IpDeviceCommandBase):
    COMMAND = 'route'

    def __init__(self, parent, table=None):
        super(IpRouteCommand, self).__init__(parent)
        self._table = table

    def table(self, table):
        """Return an instance of IpRouteCommand which works on given table"""
        return IpRouteCommand(self._parent, table)

    def _table_args(self, override=None):
        if override:
            return ['table', override]
        return ['table', self._table] if self._table else []

    def _dev_args(self):
        return ['dev', self.name] if self.name else []

    def add_gateway(self, gateway, metric=None, table=None):
        ip_version = get_ip_version(gateway)
        args = ['replace', 'default', 'via', gateway]
        if metric:
            args += ['metric', metric]
        args += self._dev_args()
        args += self._table_args(table)
        self._as_root([ip_version], tuple(args))

    def _run_as_root_detect_device_not_found(self, *args, **kwargs):
        try:
            return self._as_root(*args, **kwargs)
        except RuntimeError as rte:
            with excutils.save_and_reraise_exception() as ctx:
                if "Cannot find device" in str(rte):
                    ctx.reraise = False
                    raise exceptions.DeviceNotFoundError(device_name=self.name)

    def delete_gateway(self, gateway, table=None):
        ip_version = get_ip_version(gateway)
        args = ['del', 'default',
                'via', gateway]
        args += self._dev_args()
        args += self._table_args(table)
        self._run_as_root_detect_device_not_found([ip_version], tuple(args))

    def _parse_routes(self, ip_version, output, **kwargs):
        for line in output.splitlines():
            parts = line.split()

            # Format of line is: "<cidr>|default [<key> <value>] ..."
            route = {k: v for k, v in zip(parts[1::2], parts[2::2])}
            route['cidr'] = parts[0]
            # Avoids having to explicitly pass around the IP version
            if route['cidr'] == 'default':
                route['cidr'] = constants.IP_ANY[ip_version]

            # ip route drops things like scope and dev from the output if it
            # was specified as a filter.  This allows us to add them back.
            if self.name:
                route['dev'] = self.name
            if self._table:
                route['table'] = self._table
            # Callers add any filters they use as kwargs
            route.update(kwargs)

            yield route

    def list_routes(self, ip_version, **kwargs):
        args = ['list']
        args += self._dev_args()
        args += self._table_args()
        for k, v in kwargs.items():
            args += [k, v]

        output = self._run([ip_version], tuple(args))
        return [r for r in self._parse_routes(ip_version, output, **kwargs)]

    def list_onlink_routes(self, ip_version):
        routes = self.list_routes(ip_version, scope='link')
        return [r for r in routes if 'src' not in r]

    def add_onlink_route(self, cidr):
        self.add_route(cidr, scope='link')

    def delete_onlink_route(self, cidr):
        self.delete_route(cidr, scope='link')

    def get_gateway(self, scope=None, filters=None, ip_version=None):
        options = [ip_version] if ip_version else []

        args = ['list']
        args += self._dev_args()
        args += self._table_args()
        if filters:
            args += filters

        retval = None

        if scope:
            args += ['scope', scope]

        route_list_lines = self._run(options, tuple(args)).split('\n')
        default_route_line = next((x.strip() for x in
                                   route_list_lines if
                                   x.strip().startswith('default')), None)
        if default_route_line:
            retval = dict()
            gateway = DEFAULT_GW_PATTERN.search(default_route_line)
            if gateway:
                retval.update(gateway=gateway.group(1))
            metric = METRIC_PATTERN.search(default_route_line)
            if metric:
                retval.update(metric=int(metric.group(1)))

        return retval

    @debtcollector.removals.remove(message="Will be removed in the N cycle.")
    def pullup_route(self, interface_name, ip_version):
        """Ensures that the route entry for the interface is before all
        others on the same subnet.
        """
        options = [ip_version]
        device_list = []
        device_route_list_lines = self._run(options,
                                            ('list',
                                             'proto', 'kernel',
                                             'dev', interface_name)
                                            ).split('\n')
        for device_route_line in device_route_list_lines:
            try:
                subnet = device_route_line.split()[0]
            except Exception:
                continue
            subnet_route_list_lines = self._run(options,
                                                ('list',
                                                 'proto', 'kernel',
                                                 'match', subnet)
                                                ).split('\n')
            for subnet_route_line in subnet_route_list_lines:
                i = iter(subnet_route_line.split())
                while(next(i) != 'dev'):
                    pass
                device = next(i)
                try:
                    while(next(i) != 'src'):
                        pass
                    src = next(i)
                except Exception:
                    src = ''
                if device != interface_name:
                    device_list.append((device, src))
                else:
                    break

            for (device, src) in device_list:
                self._as_root(options, ('del', subnet, 'dev', device))
                if (src != ''):
                    self._as_root(options,
                                  ('append', subnet,
                                   'proto', 'kernel',
                                   'src', src,
                                   'dev', device))
                else:
                    self._as_root(options,
                                  ('append', subnet,
                                   'proto', 'kernel',
                                   'dev', device))

    def add_route(self, cidr, via=None, table=None, **kwargs):
        ip_version = get_ip_version(cidr)
        args = ['replace', cidr]
        if via:
            args += ['via', via]
        args += self._dev_args()
        args += self._table_args(table)
        for k, v in kwargs.items():
            args += [k, v]
        self._run_as_root_detect_device_not_found([ip_version], tuple(args))

    def delete_route(self, cidr, via=None, table=None, **kwargs):
        ip_version = get_ip_version(cidr)
        args = ['del', cidr]
        if via:
            args += ['via', via]
        args += self._dev_args()
        args += self._table_args(table)
        for k, v in kwargs.items():
            args += [k, v]
        self._run_as_root_detect_device_not_found([ip_version], tuple(args))


class IPRoute(SubProcessBase):
    def __init__(self, namespace=None, table=None):
        super(IPRoute, self).__init__(namespace=namespace)
        self.name = None
        self.route = IpRouteCommand(self, table=table)


class IpNeighCommand(IpDeviceCommandBase):
    COMMAND = 'neigh'

    def add(self, ip_address, mac_address):
        ip_version = get_ip_version(ip_address)
        self._as_root([ip_version],
                      ('replace', ip_address,
                       'lladdr', mac_address,
                       'nud', 'permanent',
                       'dev', self.name))

    def delete(self, ip_address, mac_address):
        ip_version = get_ip_version(ip_address)
        self._as_root([ip_version],
                      ('del', ip_address,
                       'lladdr', mac_address,
                       'dev', self.name))

    def show(self, ip_version):
        options = [ip_version]
        return self._as_root(options,
                             ('show',
                              'dev', self.name))

    def flush(self, ip_version, ip_address):
        """Flush neighbour entries

        Given address entry is removed from neighbour cache (ARP or NDP). To
        flush all entries pass string 'all' as an address.

        :param ip_version: Either 4 or 6 for IPv4 or IPv6 respectively
        :param ip_address: The prefix selecting the neighbours to flush
        """
        self._as_root([ip_version], ('flush', 'to', ip_address))


class IpNetnsCommand(IpCommandBase):
    COMMAND = 'netns'

    def add(self, name):
        self._as_root([], ('add', name), use_root_namespace=True)
        wrapper = IPWrapper(namespace=name)
        wrapper.netns.execute(['sysctl', '-w',
                               'net.ipv4.conf.all.promote_secondaries=1'])
        return wrapper

    def delete(self, name):
        self._as_root([], ('delete', name), use_root_namespace=True)

    def execute(self, cmds, addl_env=None, check_exit_code=True,
                log_fail_as_error=True, extra_ok_codes=None,
                run_as_root=False):
        ns_params = []
        kwargs = {'run_as_root': run_as_root}
        if self._parent.namespace:
            kwargs['run_as_root'] = True
            ns_params = ['ip', 'netns', 'exec', self._parent.namespace]

        env_params = []
        if addl_env:
            env_params = (['env'] +
                          ['%s=%s' % pair for pair in addl_env.items()])
        cmd = ns_params + env_params + list(cmds)
        return utils.execute(cmd, check_exit_code=check_exit_code,
                             extra_ok_codes=extra_ok_codes,
                             log_fail_as_error=log_fail_as_error, **kwargs)

    def exists(self, name):
        if not cfg.CONF.AGENT.use_helper_for_ns_read:
            return name in os.listdir(IP_NETNS_PATH)

        output = self._parent._execute(
            ['o'], 'netns', ['list'], run_as_root=True)
        for line in [l.split()[0] for l in output.splitlines()]:
            if name == line:
                return True
        return False


def vlan_in_use(segmentation_id, namespace=None):
    """Return True if VLAN ID is in use by an interface, else False."""
    ip_wrapper = IPWrapper(namespace=namespace)
    interfaces = ip_wrapper.netns.execute(["ip", "-d", "link", "list"],
                                          check_exit_code=True)
    return '802.1Q id %s ' % segmentation_id in interfaces


def vxlan_in_use(segmentation_id, namespace=None):
    """Return True if VXLAN VNID is in use by an interface, else False."""
    ip_wrapper = IPWrapper(namespace=namespace)
    interfaces = ip_wrapper.netns.execute(["ip", "-d", "link", "list"],
                                          check_exit_code=True)
    return 'vxlan id %s ' % segmentation_id in interfaces


def device_exists(device_name, namespace=None):
    """Return True if the device exists in the namespace."""
    return IPDevice(device_name, namespace=namespace).exists()


def device_exists_with_ips_and_mac(device_name, ip_cidrs, mac, namespace=None):
    """Return True if the device with the given IP addresses and MAC address
    exists in the namespace.
    """
    try:
        device = IPDevice(device_name, namespace=namespace)
        if mac != device.link.address:
            return False
        device_ip_cidrs = [ip['cidr'] for ip in device.addr.list()]
        for ip_cidr in ip_cidrs:
            if ip_cidr not in device_ip_cidrs:
                return False
    except RuntimeError:
        return False
    else:
        return True


def get_routing_table(ip_version, namespace=None):
    """Return a list of dictionaries, each representing a route.

    @param ip_version: the routes of version to return, for example 4
    @param namespace
    @return: a list of dictionaries, each representing a route.
    The dictionary format is: {'destination': cidr,
                               'nexthop': ip,
                               'device': device_name,
                               'scope': scope}
    """

    ip_wrapper = IPWrapper(namespace=namespace)
    table = ip_wrapper.netns.execute(
        ['ip', '-%s' % ip_version, 'route'],
        check_exit_code=True)

    routes = []
    # Example for route_lines:
    # default via 192.168.3.120 dev wlp3s0  proto static  metric 1024
    # 10.0.0.0/8 dev tun0  proto static  scope link  metric 1024
    # The first column is the destination, followed by key/value pairs.
    # The generator splits the routing table by newline, then strips and splits
    # each individual line.
    route_lines = (line.split() for line in table.split('\n') if line.strip())
    for route in route_lines:
        network = route[0]
        # Create a dict of key/value pairs (For example - 'dev': 'tun0')
        # excluding the first column.
        data = dict(route[i:i + 2] for i in range(1, len(route), 2))
        routes.append({'destination': network,
                       'nexthop': data.get('via'),
                       'device': data.get('dev'),
                       'scope': data.get('scope')})
    return routes


def ensure_device_is_ready(device_name, namespace=None):
    dev = IPDevice(device_name, namespace=namespace)
    dev.set_log_fail_as_error(False)
    try:
        # Ensure the device is up, even if it is already up. If the device
        # doesn't exist, a RuntimeError will be raised.
        dev.link.set_up()
    except RuntimeError:
        return False
    return True


def iproute_arg_supported(command, arg):
    command += ['help']
    stdout, stderr = utils.execute(command, check_exit_code=False,
                                   return_stderr=True, log_fail_as_error=False)
    return any(arg in line for line in stderr.split('\n'))


def _arping(ns_name, iface_name, address, count):
    # Pass -w to set timeout to ensure exit if interface removed while running
    arping_cmd = ['arping', '-A', '-I', iface_name, '-c', count,
                  '-w', 1.5 * count, address]
    try:
        ip_wrapper = IPWrapper(namespace=ns_name)
        ip_wrapper.netns.execute(arping_cmd, check_exit_code=True)
    except Exception:
        msg = _LE("Failed sending gratuitous ARP "
                  "to %(addr)s on %(iface)s in namespace %(ns)s")
        LOG.exception(msg, {'addr': address,
                            'iface': iface_name,
                            'ns': ns_name})


def send_ip_addr_adv_notif(ns_name, iface_name, address, config):
    """Send advance notification of an IP address assignment.

    If the address is in the IPv4 family, send gratuitous ARP.

    If the address is in the IPv6 family, no advance notification is
    necessary, since the Neighbor Discovery Protocol (NDP), Duplicate
    Address Discovery (DAD), and (for stateless addresses) router
    advertisements (RAs) are sufficient for address resolution and
    duplicate address detection.
    """
    count = config.send_arp_for_ha

    def arping():
        _arping(ns_name, iface_name, address, count)

    if count > 0 and netaddr.IPAddress(address).version == 4:
        eventlet.spawn_n(arping)


def add_namespace_to_cmd(cmd, namespace=None):
    """Add an optional namespace to the command."""

    return ['ip', 'netns', 'exec', namespace] + cmd if namespace else cmd


def get_ip_version(ip_or_cidr):
    return netaddr.IPNetwork(ip_or_cidr).version


def get_ipv6_lladdr(mac_addr):
    return '%s/64' % netaddr.EUI(mac_addr).ipv6_link_local()
