iproute.py

# -*- coding: utf-8 -*-
'''

IPRoute quickstart
------------------

**IPRoute** in two words::

    $ sudo pip install pyroute2

    $ cat example.py
    from pyroute2 import IPRoute
    ip = IPRoute()
    print([x.get_attr('IFLA_IFNAME') for x in ip.get_links()])

    $ python example.py
    ['lo', 'p6p1', 'wlan0', 'virbr0', 'virbr0-nic']

Responses
---------

The pyroute2 netlink socket implementation is agnostic
to the particular netlink protocols, and always returns
a list of messages as the response to a request sent to
the kernel::

    # this request returns one match
    eth0 = ipr.link_lookup(ifname='eth0')
    len(eth0)  # -> 1, if exists, else 0

    # but that one returns a set of
    up = ipr.link_lookup(operstate='UP')
    len(up)  # -> k, where 0 <= k <= [interface count]

Thus, always expect a list in the response, running any
`IPRoute()` netlink request.

NLMSG_ERROR responses
~~~~~~~~~~~~~~~~~~~~~

Some kernel subsystems return `NLMSG_ERROR` in the response
to any request. It is OK as long as
`nlmsg["header"]["error"] is None`. Otherwise an
exception will be raised by the parser.

So if instead of an exception you get a `NLMSG_ERROR` message,
it means `error == 0`, the same as `$? == 0` in bash.

How to work with messages
~~~~~~~~~~~~~~~~~~~~~~~~~

Every netlink message contains header, fields and NLAs
(netlink attributes). Every NLA is a netlink message...
(see "recursion").

And the library provides parsed messages according to
this scheme. Every RTNL message contains:

* `nlmsg['header']` -- parsed header
* `nlmsg['attrs']` -- NLA chain (parsed on demand)
* 0 .. k data fields, e.g. `nlmsg['flags']` etc.
* `nlmsg.header` -- the header fields spec
* `nlmsg.fields` -- the data fields spec
* `nlmsg.nla_map` -- NLA spec

An important parser feature is that NLAs are parsed
on demand, when someone tries to access them. Otherwise
the parser doesn't waste CPU cycles.

The NLA chain is a list-like structure, not a dictionary.
The netlink standard doesn't require NLAs to be unique
within one message::

    {'__align': (),
     'attrs': [('IFLA_IFNAME', 'lo'),    # [1]
               ('IFLA_TXQLEN', 1),
               ('IFLA_OPERSTATE', 'UNKNOWN'),
               ('IFLA_LINKMODE', 0),
               ('IFLA_MTU', 65536),
               ('IFLA_GROUP', 0),
               ('IFLA_PROMISCUITY', 0),
               ('IFLA_NUM_TX_QUEUES', 1),
               ('IFLA_NUM_RX_QUEUES', 1),
               ('IFLA_CARRIER', 1),
               ...],
     'change': 0,
     'event': 'RTM_NEWLINK',             # [2]
     'family': 0,
     'flags': 65609,
     'header': {'error': None,           # [3]
                'flags': 2,
                'length': 1180,
                'pid': 28233,
                'sequence_number': 257,  # [4]
                'type': 16},             # [5]
     'ifi_type': 772,
     'index': 1}

     # [1] every NLA is parsed upon access
     # [2] this field is injected by the RTNL parser
     # [3] if not None, an exception will be raised
     # [4] more details in the netlink description
     # [5] 16 == RTM_NEWLINK

To access fields::

    msg['index'] == 1

To access one NLA::

    msg.get_attr('IFLA_CARRIER') == 1

When the NLA with the specified name is not present in the
chain, `get_attr()` returns `None`. To get the list of all
NLAs of that name, use `get_attrs()`. A real example with
NLA hierarchy, take notice of `get_attr()` and
`get_attrs()` usage::

    # for macvlan interfaces there may be several
    # IFLA_MACVLAN_MACADDR NLA provided, so use
    # get_attrs() to get all the list, not only
    # the first one

    (msg
     .get_attr('IFLA_LINKINFO')           # one NLA
     .get_attr('IFLA_INFO_DATA')          # one NLA
     .get_attrs('IFLA_MACVLAN_MACADDR'))  # a list of

Pls read carefully the message structure prior to start the
coding.

Threaded vs. threadless architecture
------------------------------------

Since v0.3.2, IPRoute class is threadless by default.
It spawns no additional threads, and receives only
responses to own requests, no broadcast messages. So,
if you prefer not to cope with implicit threading, you
can safely use this module.

To get broadcast messages, use `IPRoute.bind()` call.
Please notice, that after calling `IPRoute.bind()` you
MUST get all the messages in time. In the case of the
kernel buffer overflow, you will have to restart the
socket.

With `IPRoute.bind(async=True)` one can launch async
message receiver thread with `Queue`-based buffer. The
buffer is thread-safe and completely transparent from
the programmer's perspective. Please read also
`NetlinkSocket` documentation to know more about async
mode.

Think about IPDB
----------------

If you plan to regularly fetch loads of objects, think
about IPDB also. Unlike to IPRoute, IPDB does not fetch
all the objects from OS every time you request them, but
keeps a cache that is asynchronously updated by the netlink
broadcasts. For a long-term running programs, that often
retrieve info about hundreds or thousands of objects, it
can be better to use IPDB as it will load CPU significantly
less.

API
---
'''
import errno
import types
import logging
from socket import AF_INET
from socket import AF_INET6
from socket import AF_UNSPEC
from socket import AF_BRIDGE
from pyroute2.netlink import NLMSG_DONE
from pyroute2.netlink import NLMSG_ERROR
from pyroute2.netlink import NLM_F_ATOMIC
from pyroute2.netlink import NLM_F_ROOT
from pyroute2.netlink import NLM_F_REPLACE
from pyroute2.netlink import NLM_F_REQUEST
from pyroute2.netlink import NLM_F_ACK
from pyroute2.netlink import NLM_F_DUMP
from pyroute2.netlink import NLM_F_CREATE
from pyroute2.netlink import NLM_F_EXCL
from pyroute2.netlink import NLM_F_APPEND
from pyroute2.netlink.rtnl import RTM_NEWADDR
from pyroute2.netlink.rtnl import RTM_GETADDR
from pyroute2.netlink.rtnl import RTM_DELADDR
from pyroute2.netlink.rtnl import RTM_NEWLINK
from pyroute2.netlink.rtnl import RTM_GETLINK
from pyroute2.netlink.rtnl import RTM_DELLINK
from pyroute2.netlink.rtnl import RTM_NEWQDISC
from pyroute2.netlink.rtnl import RTM_GETQDISC
from pyroute2.netlink.rtnl import RTM_DELQDISC
from pyroute2.netlink.rtnl import RTM_NEWTFILTER
from pyroute2.netlink.rtnl import RTM_GETTFILTER
from pyroute2.netlink.rtnl import RTM_DELTFILTER
from pyroute2.netlink.rtnl import RTM_NEWTCLASS
from pyroute2.netlink.rtnl import RTM_GETTCLASS
from pyroute2.netlink.rtnl import RTM_DELTCLASS
from pyroute2.netlink.rtnl import RTM_NEWRULE
from pyroute2.netlink.rtnl import RTM_GETRULE
from pyroute2.netlink.rtnl import RTM_DELRULE
from pyroute2.netlink.rtnl import RTM_NEWROUTE
from pyroute2.netlink.rtnl import RTM_GETROUTE
from pyroute2.netlink.rtnl import RTM_DELROUTE
from pyroute2.netlink.rtnl import RTM_NEWNEIGH
from pyroute2.netlink.rtnl import RTM_GETNEIGH
from pyroute2.netlink.rtnl import RTM_DELNEIGH
from pyroute2.netlink.rtnl import RTM_SETLINK
from pyroute2.netlink.rtnl import RTM_GETNEIGHTBL
from pyroute2.netlink.rtnl import TC_H_ROOT
from pyroute2.netlink.rtnl import rt_type
from pyroute2.netlink.rtnl import rt_scope
from pyroute2.netlink.rtnl import rt_proto
from pyroute2.netlink.rtnl.req import IPLinkRequest
from pyroute2.netlink.rtnl.req import IPBridgeRequest
from pyroute2.netlink.rtnl.req import IPBrPortRequest
from pyroute2.netlink.rtnl.req import IPRouteRequest
from pyroute2.netlink.rtnl.req import IPRuleRequest
from pyroute2.netlink.rtnl.tcmsg import plugins as tc_plugins
from pyroute2.netlink.rtnl.tcmsg import tcmsg
from pyroute2.netlink.rtnl.rtmsg import rtmsg
from pyroute2.netlink.rtnl import ndmsg
from pyroute2.netlink.rtnl.ndtmsg import ndtmsg
from pyroute2.netlink.rtnl.fibmsg import fibmsg
from pyroute2.netlink.rtnl.ifinfmsg import ifinfmsg
from pyroute2.netlink.rtnl.ifaddrmsg import ifaddrmsg
from pyroute2.netlink.rtnl.iprsocket import IPRSocket
from pyroute2.netlink.rtnl.iprsocket import IPBatchSocket
from pyroute2.netlink.rtnl.riprsocket import RawIPRSocket

from pyroute2.common import AF_MPLS
from pyroute2.common import basestring
from pyroute2.common import getbroadcast
from pyroute2.netlink.exceptions import NetlinkError

DEFAULT_TABLE = 254
log = logging.getLogger(__name__)


def transform_handle(handle):
    if isinstance(handle, basestring):
        (major, minor) = [int(x if x else '0', 16) for x in handle.split(':')]
        handle = (major << 8 * 2) | minor
    return handle


class IPRouteMixin(object):
    '''
    `IPRouteMixin` should not be instantiated by itself. It is intended
    to be used as a mixin class that provides RTNL API. Following classes
    use `IPRouteMixin`:

    * `IPRoute` -- RTNL API to the current network namespace
    * `NetNS` -- RTNL API to another network namespace
    * `IPBatch` -- RTNL compiler

    It is an old-school API, that provides access to rtnetlink as is.
    It helps you to retrieve and change almost all the data, available
    through rtnetlink::

        from pyroute2 import IPRoute
        ipr = IPRoute()
        # create an interface
        ipr.link('add', ifname='brx', kind='bridge')
        # lookup the index
        dev = ipr.link_lookup(ifname='brx')[0]
        # bring it down
        ipr.link('set', index=dev, state='down')
        # change the interface MAC address and rename it just for fun
        ipr.link('set', index=dev,
                 address='00:11:22:33:44:55',
                 ifname='br-ctrl')
        # add primary IP address
        ipr.addr('add', index=dev,
                 address='10.0.0.1', mask=24,
                 broadcast='10.0.0.255')
        # add secondary IP address
        ipr.addr('add', index=dev,
                 address='10.0.0.2', mask=24,
                 broadcast='10.0.0.255')
        # bring it up
        ipr.link('set', index=dev, state='up')
    '''

    def _match(self, match, msgs):
        # filtered results
        f_ret = []
        for msg in msgs:
            if hasattr(match, '__call__'):
                if match(msg):
                    f_ret.append(msg)
            elif isinstance(match, dict):
                matches = []
                for key in match:
                    KEY = msg.name2nla(key)
                    if isinstance(match[key], types.FunctionType):
                        if msg.get(key) is not None:
                            matches.append(match[key](msg.get(key)))
                        elif msg.get_attr(KEY) is not None:
                            matches.append(match[key](msg.get_attr(KEY)))
                        else:
                            matches.append(False)
                    else:
                        matches.append(msg.get(key) == match[key] or
                                       msg.get_attr(KEY) ==
                                       match[key])
                if all(matches):
                    f_ret.append(msg)
        return f_ret

    # 8<---------------------------------------------------------------
    #
    # Listing methods
    #
    def get_qdiscs(self, index=None):
        '''
        Get all queue disciplines for all interfaces or for specified
        one.
        '''
        msg = tcmsg()
        msg['family'] = AF_UNSPEC
        ret = self.nlm_request(msg, RTM_GETQDISC)
        if index is None:
            return ret
        else:
            return [x for x in ret if x['index'] == index]

    def get_filters(self, index=0, handle=0, parent=0):
        '''
        Get filters for specified interface, handle and parent.
        '''
        msg = tcmsg()
        msg['family'] = AF_UNSPEC
        msg['index'] = index
        msg['handle'] = handle
        msg['parent'] = parent
        return self.nlm_request(msg, RTM_GETTFILTER)

    def get_classes(self, index=0):
        '''
        Get classes for specified interface.
        '''
        msg = tcmsg()
        msg['family'] = AF_UNSPEC
        msg['index'] = index
        return self.nlm_request(msg, RTM_GETTCLASS)

    def get_vlans(self, **kwarg):
        '''
        Dump available vlan info on bridge ports
        '''
        # IFLA_EXT_MASK, extended info mask
        #
        # include/uapi/linux/rtnetlink.h
        # 1 << 0 => RTEXT_FILTER_VF
        # 1 << 1 => RTEXT_FILTER_BRVLAN
        # 1 << 2 => RTEXT_FILTER_BRVLAN_COMPRESSED
        # 1 << 3 => RTEXT_FILTER_SKIP_STATS
        #
        # maybe place it as mapping into ifinfomsg.py?
        #
        match = kwarg.get('match', None) or kwarg or None
        return self.link('dump', family=AF_BRIDGE, ext_mask=2, match=match)

    def get_links(self, *argv, **kwarg):
        '''
        Get network interfaces.

        By default returns all interfaces. Arguments vector
        can contain interface indices or a special keyword
        'all'::

            ip.get_links()
            ip.get_links('all')
            ip.get_links(1, 2, 3)

            interfaces = [1, 2, 3]
            ip.get_links(*interfaces)
        '''
        result = []
        links = argv or [0]
        if links[0] == 'all':  # compat syntax
            links = [0]

        if links[0] == 0:
            cmd = 'dump'
        else:
            cmd = 'get'

        for index in links:
            kwarg['index'] = index
            result.extend(self.link(cmd, **kwarg))
        return result

    def get_neighbors(self, family=AF_UNSPEC):
        '''
        Alias of `get_neighbours()`, deprecated.
        '''
        log.warning('The `get_neighbors()` call is deprecated')
        log.warning('Use `get_neighbours() instead')
        return self.get_neighbours(family)

    def get_neighbours(self, family=AF_UNSPEC, match=None, **kwarg):
        '''
        Dump ARP cache records.

        The `family` keyword sets the family for the request:
        e.g. `AF_INET` or `AF_INET6` for arp cache, `AF_BRIDGE`
        for fdb.

        If other keyword arguments not empty, they are used as
        filter. Also, one can explicitly set filter as a function
        with the `match` parameter.

        Examples::

            # get neighbours on the 3rd link:
            ip.get_neighbours(ifindex=3)

            # get a particular record by dst:
            ip.get_neighbours(dst='172.16.0.1')

            # get fdb records:
            ip.get_neighbours(AF_BRIDGE)

            # and filter them by a function:
            ip.get_neighbours(AF_BRIDGE, match=lambda x: x['state'] == 2)
        '''
        return self.neigh('dump', family=family, match=match or kwarg)

    def get_ntables(self, family=AF_UNSPEC):
        '''
        Get neighbour tables
        '''
        msg = ndtmsg()
        msg['family'] = family
        return self.nlm_request(msg, RTM_GETNEIGHTBL)

    def get_addr(self, family=AF_UNSPEC, match=None, **kwarg):
        '''
        Dump addresses.

        If family is not specified, both AF_INET and AF_INET6 addresses
        will be dumped::

            # get all addresses
            ip.get_addr()

        It is possible to apply filters on the results::

            # get addresses for the 2nd interface
            ip.get_addr(index=2)

            # get addresses with IFA_LABEL == 'eth0'
            ip.get_addr(label='eth0')

            # get all the subnet addresses on the interface, identified
            # by broadcast address (should be explicitly specified upon
            # creation)
            ip.get_addr(index=2, broadcast='192.168.1.255')

        A custom predicate can be used as a filter::

            ip.get_addr(match=lambda x: x['index'] == 1)
        '''
        return self.addr((RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP),
                         family=family,
                         match=match or kwarg)

    def get_rules(self, family=AF_UNSPEC, match=None, **kwarg):
        '''
        Get all rules. By default return all rules. To explicitly
        request the IPv4 rules use `family=AF_INET`.

        Example::
            ip.get_rules() # get all the rules for all families
            ip.get_rules(family=AF_INET6)  # get only IPv6 rules
        '''
        return self.rule((RTM_GETRULE,
                          NLM_F_REQUEST | NLM_F_ROOT | NLM_F_ATOMIC),
                         family=family,
                         match=match or kwarg)

    def get_routes(self, family=AF_UNSPEC, match=None, **kwarg):
        '''
        Get all routes. You can specify the table. There
        are 255 routing classes (tables), and the kernel
        returns all the routes on each request. So the
        routine filters routes from full output.

        Example::

            ip.get_routes()  # get all the routes for all families
            ip.get_routes(family=AF_INET6)  # get only IPv6 routes
            ip.get_routes(table=254)  # get routes from 254 table
        '''

        msg_flags = NLM_F_DUMP | NLM_F_REQUEST
        nkw = {}
        nkw['callback'] = kwarg.pop('callback', None)

        # get a particular route?
        if isinstance(kwarg.get('dst'), basestring):
            dlen = 32 if family == AF_INET else \
                128 if family == AF_INET6 else 0
            msg_flags = NLM_F_REQUEST
            nkw['dst'] = kwarg.pop('dst')
            nkw['dst_len'] = kwarg.pop('dst_len', dlen)

        return self.route((RTM_GETROUTE, msg_flags),
                          family=family, match=match or kwarg, **nkw)
    # 8<---------------------------------------------------------------

    # 8<---------------------------------------------------------------
    #
    # Shortcuts
    #
    def get_default_routes(self, family=AF_UNSPEC, table=DEFAULT_TABLE):
        '''
        Get default routes
        '''
        # according to iproute2/ip/iproute.c:print_route()
        return [x for x in self.get_routes(family, table=table)
                if (x.get_attr('RTA_DST', None) is None and
                    x['dst_len'] == 0)]

    def link_create(self, **kwarg):
        # Create interface
        #
        # Obsoleted method. Use `link("add", ...)` instead.
        log.warning("link_create() is obsoleted, use link('add', ...)")
        return self.link('add', **IPLinkRequest(kwarg))

    def link_up(self, index):
        # Link up.
        #
        # Obsoleted method. Use `link("set", ...)` instead.
        log.warning("link_up() is obsoleted, use link('set', ...)")
        return self.link('set', index=index, state='up')

    def link_down(self, index):
        # Link up.
        #
        # Obsoleted method. Use `link("set", ...)` instead.
        log.warning("link_down() is obsoleted, use link('set', ...)")
        return self.link('set', index=index, state='down')

    def link_rename(self, index, name):
        # Rename interface.
        #
        # Obsoleted method. Use `link("set", ...)` instead.
        log.warning("link_rename() is obsoleted, use link('set', ...)")
        return self.link('set', index=index, ifname=name)

    def link_remove(self, index):
        # Remove interface.
        #
        # Obsoleted method. Use `link("del", ...)` instead.
        log.warning("link_remove() is obsoleted, use link('del', ...)")
        return self.link('del', index=index)

    def link_lookup(self, **kwarg):
        '''
        Lookup interface index (indeces) by first level NLA
        value.

        Example::

            ip.link_lookup(address="52:54:00:9d:4e:3d")
            ip.link_lookup(ifname="lo")
            ip.link_lookup(operstate="UP")

        Please note, that link_lookup() returns list, not one
        value.
        '''
        name = tuple(kwarg.keys())[0]
        value = kwarg[name]

        name = str(name).upper()
        if not name.startswith('IFLA_'):
            name = 'IFLA_%s' % (name)

        return [k['index'] for k in
                [i for i in self.get_links() if 'attrs' in i] if
                [l for l in k['attrs'] if l[0] == name and l[1] == value]]
    # 8<---------------------------------------------------------------

    # 8<---------------------------------------------------------------
    #
    # Shortcuts to flush RTNL objects
    #
    def flush_routes(self, *argv, **kwarg):
        '''
        Flush routes -- purge route records from a table.
        Arguments are the same as for `get_routes()`
        routine. Actually, this routine implements a pipe from
        `get_routes()` to `nlm_request()`.
        '''
        ret = []
        match = kwarg.get('match') or kwarg

        def callback(msg):
            if msg['header']['type'] == NLMSG_DONE:
                # this message will pass to the get()
                return False
            if self._match(match, [msg]):
                # delete matching routes
                self.put(msg, msg_type=RTM_DELROUTE, msg_flags=NLM_F_REQUEST)
            return True

        nkw = {}
        nkw.update(kwarg)
        nkw['table'] = kwarg.get('table', 0)
        nkw['callback'] = callback
        self.get_routes(*argv, **nkw)
        return ret

    def flush_addr(self, *argv, **kwarg):
        '''
        Flush IP addresses.

        Examples::

            # flush all addresses on the interface with index 2:
            ipr.flush_addr(index=2)

            # flush all addresses with IFA_LABEL='eth0':
            ipr.flush_addr(label='eth0')
        '''
        flags = NLM_F_ACK | NLM_F_CREATE | NLM_F_EXCL | NLM_F_REQUEST
        ret = []
        for addr in self.get_addr(*argv, **kwarg):
            try:
                ret.append(self.nlm_request(addr,
                                            msg_type=RTM_DELADDR,
                                            msg_flags=flags))
            except NetlinkError as e:
                if e.code != errno.EADDRNOTAVAIL:
                    raise
        return ret

    def flush_rules(self, *argv, **kwarg):
        '''
        Flush rules. Please keep in mind, that by default the function
        operates on **all** rules of **all** families. To work only on
        IPv4 rules, one should explicitly specify `family=AF_INET`.

        Examples::

            # flush all IPv4 rule with priorities above 5 and below 32000
            ipr.flush_rules(family=AF_INET, priority=lambda x: 5 < x < 32000)

            # flush all IPv6 rules that point to table 250:
            ipr.flush_rules(family=socket.AF_INET6, table=250)
        '''
        flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_CREATE | NLM_F_EXCL
        ret = []
        for rule in self.get_rules(*argv, **kwarg):
            ret.append(self.nlm_request(rule,
                                        msg_type=RTM_DELRULE,
                                        msg_flags=flags))
        return ret
    # 8<---------------------------------------------------------------

    # 8<---------------------------------------------------------------
    #
    # Extensions to low-level functions
    #
    def brport(self, command, **kwarg):
        '''
        Set bridge port parameters. Example::

            idx = ip.link_lookup(ifname='eth0')
            ip.brport("set", index=idx, unicast_flood=0, cost=200)
            ip.brport("show", index=idx)

        Possible keywords are NLA names for the `protinfo_bridge` class,
        without the prefix and in lower letters.
        '''
        if (command in ('dump', 'show')) and ('match' not in kwarg):
            match = kwarg
        else:
            match = kwarg.pop('match', None)

        flags_dump = NLM_F_REQUEST | NLM_F_DUMP
        flags_req = NLM_F_REQUEST | NLM_F_ACK
        commands = {'set': (RTM_SETLINK, flags_req),
                    'dump': (RTM_GETLINK, flags_dump),
                    'show': (RTM_GETLINK, flags_dump)}
        (command, msg_flags) = commands.get(command, command)

        msg = ifinfmsg()
        if command == RTM_GETLINK:
            msg['index'] = kwarg.get('index', 0)
        else:
            msg['index'] = kwarg.pop('index', 0)
        msg['family'] = AF_BRIDGE
        protinfo = IPBrPortRequest(kwarg)
        msg['attrs'].append(('IFLA_PROTINFO', protinfo, 0x8000))
        ret = self.nlm_request(msg,
                               msg_type=command,
                               msg_flags=msg_flags)
        if match is not None:
            return self._match(match, ret)
        else:
            return ret

    def vlan_filter(self, command, **kwarg):
        '''
        Vlan filters is another approach to support vlans in Linux.
        Before vlan filters were introduced, there was only one way
        to bridge vlans: one had to create vlan interfaces and
        then add them as ports::

                    +------+      +----------+
            net --> | eth0 | <--> | eth0.500 | <---+
                    +------+      +----------+     |
                                                   v
                    +------+                    +-----+
            net --> | eth1 |                    | br0 |
                    +------+                    +-----+
                                                   ^
                    +------+      +----------+     |
            net --> | eth2 | <--> | eth0.500 | <---+
                    +------+      +----------+

        It means that one has to create as many bridges, as there were
        vlans. Vlan filters allow to bridge together underlying interfaces
        and create vlans already on the bridge::

            # v500 label shows which interfaces have vlan filter

                    +------+ v500
            net --> | eth0 | <-------+
                    +------+         |
                                     v
                    +------+      +-----+    +---------+
            net --> | eth1 | <--> | br0 |<-->| br0v500 |
                    +------+      +-----+    +---------+
                                     ^
                    +------+ v500    |
            net --> | eth2 | <-------+
                    +------+

        In this example vlan 500 will be allowed only on ports `eth0` and
        `eth2`, though all three eth nics are bridged.

        Some example code::

            # create bridge
            ip.link("add",
                    ifname="br0",
                    kind="bridge")

            # attach a port
            ip.link("set",
                    index=ip.link_lookup(ifname="eth0")[0],
                    master=ip.link_lookup(ifname="br0")[0])

            # set vlan filter
            ip.vlan_filter("add",
                           index=ip.link_lookup(ifname="eth0")[0],
                           vlan_info={"vid": 500})

            # create vlan interface on the bridge
            ip.link("add",
                    ifname="br0v500",
                    kind="vlan",
                    link=ip.link_lookup(ifname="br0")[0],
                    vlan_id=500)

            # set all UP
            ip.link("set",
                    index=ip.link_lookup(ifname="br0")[0],
                    state="up")
            ip.link("set",
                    index=ip.link_lookup(ifname="br0v500")[0],
                    state="up")
            ip.link("set",
                    index=ip.link_lookup(ifname="eth0")[0],
                    state="up")

            # set IP address
            ip.addr("add",
                    index=ip.link_lookup(ifname="br0v500")[0],
                    address="172.16.5.2",
                    mask=24)

            Now all the traffic to the network 172.16.5.2/24 will go
            to vlan 500 only via ports that have such vlan filter.


        Required arguments for `vlan_filter()` -- `index` and `vlan_info`.
        Vlan info struct::

            {"vid": uint16,
             "flags": uint16}

        More details:
            * kernel:Documentation/networking/switchdev.txt
            * pyroute2.netlink.rtnl.ifinfmsg:... vlan_info

        One can specify `flags` as int or as a list of flag names:
            * `master` == 0x1
            * `pvid` == 0x2
            * `untagged` == 0x4
            * `range_begin` == 0x8
            * `range_end` == 0x10
            * `brentry` == 0x20

        E.g.::

            {"vid": 20,
             "flags": ["pvid", "untagged"]}

            # is equal to
            {"vid": 20,
             "flags": 6}

        Commands:

        **add**

        Add vlan filter to a bridge port. Example::

            ip.vlan_filter("add", index=2, vlan_info={"vid": 200})

        **del**

        Remove vlan filter from a bridge port. Example::

            ip.vlan_filter("del", index=2, vlan_info={"vid": 200})

        '''
        flags_req = NLM_F_REQUEST | NLM_F_ACK
        commands = {'add': (RTM_SETLINK, flags_req),
                    'del': (RTM_DELLINK, flags_req)}

        kwarg['family'] = AF_BRIDGE
        kwarg['kwarg_filter'] = IPBridgeRequest

        (command, flags) = commands.get(command, command)
        return self.link((command, flags), **kwarg)

    def fdb(self, command, **kwarg):
        '''
        Bridge forwarding database management.

        More details:
            * kernel:Documentation/networking/switchdev.txt
            * pyroute2.netlink.rtnl.ndmsg

        **add**

        Add a new FDB record. Works in the same way as ARP cache
        management, but some additional NLAs can be used::

            # simple FDB record
            #
            ip.fdb('add',
                   ifindex=ip.link_lookup(ifname='br0')[0],
                   lladdr='00:11:22:33:44:55',
                   dst='10.0.0.1')

            # specify vlan
            # NB: vlan should exist on the device, use
            # `vlan_filter()`
            #
            ip.fdb('add',
                   ifindex=ip.link_lookup(ifname='br0')[0],
                   lladdr='00:11:22:33:44:55',
                   dst='10.0.0.1',
                   vlan=200)

            # specify vxlan id and port
            # NB: works only for vxlan devices, use
            # `link("add", kind="vxlan", ...)`
            #
            # if port is not specified, the default one is used
            # by the kernel.
            #
            # if vni (vxlan id) is equal to the device vni,
            # the kernel doesn't report it back
            #
            ip.fdb('add',
                   ifindex=ip.link_lookup(ifname='vx500')[0]
                   lladdr='00:11:22:33:44:55',
                   dst='10.0.0.1',
                   port=5678,
                   vni=600)

        **append**

        Append a new FDB record. The same syntax as for **add**.

        **del**

        Remove an existing FDB record. The same syntax as for **add**.

        **dump**

        Dump all the FDB records. If any `**kwarg` is provided,
        results will be filtered::

            # dump all the records
            ip.fdb('dump')

            # show only specific lladdr, dst, vlan etc.
            ip.fdb('dump', lladdr='00:11:22:33:44:55')
            ip.fdb('dump', dst='10.0.0.1')
            ip.fdb('dump', vlan=200)

        '''
        kwarg['family'] = AF_BRIDGE
        # nud -> state
        if 'nud' in kwarg:
            kwarg['state'] = kwarg.pop('nud')
        if (command in ('add', 'del', 'append')) and \
                not (kwarg.get('state', 0) & ndmsg.states['noarp']):
            # state must contain noarp in add / del / append
            kwarg['state'] = kwarg.pop('state', 0) | ndmsg.states['noarp']
            # other assumptions
            if not kwarg.get('state', 0) & (ndmsg.states['permanent'] |
                                            ndmsg.states['reachable']):
                # permanent (default) or reachable
                kwarg['state'] |= ndmsg.states['permanent']
            if not kwarg.get('flags', 0) & (ndmsg.flags['self'] |
                                            ndmsg.flags['master']):
                # self (default) or master
                kwarg['flags'] = kwarg.get('flags', 0) | ndmsg.flags['self']
        #
        return self.neigh(command, **kwarg)

    # 8<---------------------------------------------------------------
    #
    # General low-level configuration methods
    #
    def neigh(self, command, **kwarg):
        '''
        Neighbours operations, same as `ip neigh` or `bridge fdb`

        **add**

        Add a neighbour record, e.g.::

            # add a permanent record on veth0
            idx = ip.link_lookup(ifname='veth0')[0]
            ip.neigh('add',
                     dst='172.16.45.1',
                     lladdr='00:11:22:33:44:55',
                     ifindex=ip.link_lookup(ifname='veth0')[0]
                     state=ndmsg.states['permanent'])

        **set**

        Set an existing record or create a new one, if it doesn't exist.

        **change**

        Change an existing record or fail, if it doesn't exist.

        **del**

        Delete an existing record.

        **dump**

        Dump all the records in the NDB.
        '''

        if (command == 'dump') and ('match' not in kwarg):
            match = kwarg
        else:
            match = kwarg.pop('match', None)

        flags_dump = NLM_F_REQUEST | NLM_F_DUMP
        flags_base = NLM_F_REQUEST | NLM_F_ACK
        flags_make = flags_base | NLM_F_CREATE | NLM_F_EXCL
        flags_append = flags_base | NLM_F_CREATE | NLM_F_APPEND
        flags_change = flags_base | NLM_F_REPLACE
        flags_replace = flags_change | NLM_F_CREATE

        commands = {'add': (RTM_NEWNEIGH, flags_make),
                    'set': (RTM_NEWNEIGH, flags_replace),
                    'replace': (RTM_NEWNEIGH, flags_replace),
                    'change': (RTM_NEWNEIGH, flags_change),
                    'del': (RTM_DELNEIGH, flags_make),
                    'remove': (RTM_DELNEIGH, flags_make),
                    'delete': (RTM_DELNEIGH, flags_make),
                    'dump': (RTM_GETNEIGH, flags_dump),
                    'append': (RTM_NEWNEIGH, flags_append)}

        (command, flags) = commands.get(command, command)
        if 'nud' in kwarg:
            kwarg['state'] = kwarg.pop('nud')
        msg = ndmsg.ndmsg()
        for field in msg.fields:
            msg[field[0]] = kwarg.pop(field[0], 0)
        msg['family'] = msg['family'] or AF_INET
        msg['attrs'] = []
        # fix nud kwarg
        if isinstance(msg['state'], basestring):
            msg['state'] = ndmsg.states_a2n(msg['state'])

        for key in kwarg:
            nla = ndmsg.ndmsg.name2nla(key)
            if kwarg[key] is not None:
                msg['attrs'].append([nla, kwarg[key]])

        ret = self.nlm_request(msg, msg_type=command, msg_flags=flags)
        if match is not None:
            return self._match(match, ret)
        else:
            return ret

    def link(self, command, **kwarg):
        '''
        Link operations.

        Keywords to set up ifinfmsg fields:
            * index -- interface index
            * family -- AF_BRIDGE for bridge operations, otherwise 0
            * flags -- device flags
            * change -- change mask

        All other keywords will be translated to NLA names, e.g.
        `mtu -> IFLA_MTU`, `af_spec -> IFLA_AF_SPEC` etc. You can
        provide a complete NLA structure or let filters do it for
        you. E.g., these pairs show equal statements::

            # set device MTU
            ip.link("set", index=x, mtu=1000)
            ip.link("set", index=x, IFLA_MTU=1000)

            # add vlan device
            ip.link("add", ifname="test", kind="dummy")
            ip.link("add", ifname="test",
                    IFLA_LINKINFO={'attrs': [['IFLA_INFO_KIND', 'dummy']]})

        Filters are implemented in the `pyroute2.netlink.rtnl.req` module.
        You can contribute your own if you miss shortcuts.

        Commands:

        **add**

        To create an interface, one should specify the interface kind::

            ip.link("add",
                    ifname="test",
                    kind="dummy")

        The kind can be any of those supported by kernel. It can be
        `dummy`, `bridge`, `bond` etc. On modern kernels one can specify
        even interface index::

            ip.link("add",
                    ifname="br-test",
                    kind="bridge",
                    index=2345)

        Specific type notes:

        ► gre

        Create GRE tunnel::

            ip.link("add",
                    ifname="grex",
                    kind="gre",
                    gre_local="172.16.0.1",
                    gre_remote="172.16.0.101",
                    gre_ttl=16)

        The keyed GRE requires explicit iflags/oflags specification::

            ip.link("add",
                    ifname="grex",
                    kind="gre",
                    gre_local="172.16.0.1",
                    gre_remote="172.16.0.101",
                    gre_ttl=16,
                    gre_ikey=10,
                    gre_okey=10,
                    gre_iflags=32,
                    gre_oflags=32)

        Support for GRE over IPv6 is also included; use `kind=ip6gre` and
        `ip6gre_` as the prefix for its values.

        ► macvlan

        Macvlan interfaces act like VLANs within OS. The macvlan driver
        provides an ability to add several MAC addresses on one interface,
        where every MAC address is reflected with a virtual interface in
        the system.

        In some setups macvlan interfaces can replace bridge interfaces,
        providing more simple and at the same time high-performance
        solution::

            ip.link("add",
                    ifname="mvlan0",
                    kind="macvlan",
                    link=ip.link_lookup(ifname="em1")[0],
                    macvlan_mode="private").commit()

        Several macvlan modes are available: "private", "vepa", "bridge",
        "passthru". Ususally the default is "vepa".

        ► macvtap

        Almost the same as macvlan, but creates also a character tap device::

            ip.link("add",
                    ifname="mvtap0",
                    kind="macvtap",
                    link=ip.link_lookup(ifname="em1")[0],
                    macvtap_mode="vepa").commit()

        Will create a device file `"/dev/tap%s" % index`

        ► tuntap

        Possible `tuntap` keywords:

            - `mode` — "tun" or "tap"
            - `uid` — integer
            - `gid` — integer
            - `ifr` — dict of tuntap flags (see ifinfmsg:... tuntap_data)

        Create a tap interface::

            ip.link("add",
                    ifname="tap0",
                    kind="tuntap",
                    mode="tap")

        Tun/tap interfaces are created using `ioctl()`, but the library
        provides a transparent way to manage them using netlink API.

        ► veth

        To properly create `veth` interface, one should specify
        `peer` also, since `veth` interfaces are created in pairs::

            ip.link("add", ifname="v1p0", kind="veth", peer="v1p1")

        ► vlan

        VLAN interfaces require additional parameters, `vlan_id` and
        `link`, where `link` is a master interface to create VLAN on::

            ip.link("add",
                    ifname="v100",
                    kind="vlan",
                    link=ip.link_lookup(ifname="eth0")[0],
                    vlan_id=100)

        There is a possibility to create also 802.1ad interfaces::

            # create external vlan 802.1ad, s-tag
            ip.link("add",
                    ifname="v100s",
                    kind="vlan",
                    link=ip.link_lookup(ifname="eth0")[0],
                    vlan_id=100,
                    vlan_protocol=0x88a8)

            # create internal vlan 802.1q, c-tag
            ip.link("add",
                    ifname="v100c",
                    kind="vlan",
                    link=ip.link_lookup(ifname="v100s")[0],
                    vlan_protocol=0x8100)


        ► vrf

        VRF interfaces (see linux/Documentation/networking/vrf.txt)::

            ip.link("add",
                    ifname="vrf-foo",
                    kind="vrf",
                    vrf_table=42)

        ► vxlan

        VXLAN interfaces are like VLAN ones, but require a bit more
        parameters::

            ip.link("add",
                    ifname="vx101",
                    kind="vxlan",
                    vxlan_link=ip.link_lookup(ifname="eth0")[0],
                    vxlan_id=101,
                    vxlan_group='239.1.1.1',
                    vxlan_ttl=16)

        All possible vxlan parameters are listed in the module
        `pyroute2.netlink.rtnl.ifinfmsg:... vxlan_data`.

        **set**

        Set interface attributes::

            # get interface index
            x = ip.link_lookup(ifname="eth0")[0]
            # put link down
            ip.link("set", index=x, state="down")
            # rename and set MAC addr
            ip.link("set", index=x, address="00:11:22:33:44:55", name="bala")
            # set MTU and TX queue length
            ip.link("set", index=x, mtu=1000, txqlen=2000)
            # bring link up
            ip.link("set", index=x, state="up")

        Keyword "state" is reserved. State can be "up" or "down",
        it is a shortcut::

            state="up":   flags=1, mask=1
            state="down": flags=0, mask=0

        **del**

        Destroy the interface::

            ip.link("del", index=ip.link_lookup(ifname="dummy0")[0])

        **dump**

        Dump info for all interfaces

        **get**

        Get specific interface info::

            ip.link("get", index=ip.link_lookup(ifname="br0")[0])

        **vlan-add**
        **vlan-del**

        These command names are confusing and thus are deprecated.
        Use `IPRoute.vlan_filter()`.
        '''
        if (command == 'dump') and ('match' not in kwarg):
            match = kwarg
        else:
            match = kwarg.pop('match', None)

        if command[:4] == 'vlan':
            log.warning('vlan filters are managed via `vlan_filter()`')
            log.warning('this compatibility hack will be removed soon')
            return self.vlan_filter(command[5:], **kwarg)

        flags_dump = NLM_F_REQUEST | NLM_F_DUMP
        flags_req = NLM_F_REQUEST | NLM_F_ACK
        flags_create = flags_req | NLM_F_CREATE | NLM_F_EXCL
        commands = {'set': (RTM_SETLINK, flags_create),
                    'add': (RTM_NEWLINK, flags_create),
                    'del': (RTM_DELLINK, flags_create),
                    'remove': (RTM_DELLINK, flags_create),
                    'delete': (RTM_DELLINK, flags_create),
                    'dump': (RTM_GETLINK, flags_dump),
                    'get': (RTM_GETLINK, NLM_F_REQUEST)}

        msg = ifinfmsg()
        # ifinfmsg fields
        #
        # ifi_family
        # ifi_type
        # ifi_index
        # ifi_flags
        # ifi_change
        #
        msg['family'] = kwarg.pop('family', 0)
        lrq = kwarg.pop('kwarg_filter', IPLinkRequest)
        (command, msg_flags) = commands.get(command, command)
        # index
        msg['index'] = kwarg.pop('index', 0)
        # flags
        flags = kwarg.pop('flags', 0) or 0
        # change
        mask = kwarg.pop('mask', 0) or kwarg.pop('change', 0) or 0

        # UP/DOWN shortcut
        if 'state' in kwarg:
            mask = 1                  # IFF_UP mask
            if kwarg['state'].lower() == 'up':
                flags = 1             # 0 (down) or 1 (up)
            del kwarg['state']

        msg['flags'] = flags
        msg['change'] = mask

        # apply filter
        kwarg = lrq(kwarg)

        # attach NLA
        for key in kwarg:
            nla = type(msg).name2nla(key)
            if kwarg[key] is not None:
                msg['attrs'].append([nla, kwarg[key]])

        ret = self.nlm_request(msg,
                               msg_type=command,
                               msg_flags=msg_flags)
        if match is not None:
            return self._match(match, ret)
        else:
            return ret

    def addr(self, command, index=None, address=None, mask=None,
             family=None, scope=None, match=None, **kwarg):
        '''
        Address operations

        * command -- add, delete
        * index -- device index
        * address -- IPv4 or IPv6 address
        * mask -- address mask
        * family -- socket.AF_INET for IPv4 or socket.AF_INET6 for IPv6
        * scope -- the address scope, see /etc/iproute2/rt_scopes
        * \*\*kwarg -- any ifaddrmsg field or NLA

        Later the method signature will be changed to::

            def addr(self, command, match=None, **kwarg):
                # the method body

        So only keyword arguments (except of the command) will be accepted.
        The reason for this change is an unification of API.

        Example::

            idx = 62
            ip.addr('add', index=idx, address='10.0.0.1', mask=24)
            ip.addr('add', index=idx, address='10.0.0.2', mask=24)

        With more NLAs::

            # explicitly set broadcast address
            ip.addr('add', index=idx,
                    address='10.0.0.3',
                    broadcast='10.0.0.255',
                    prefixlen=24)

            # make the secondary address visible to ifconfig: add label
            ip.addr('add', index=idx,
                    address='10.0.0.4',
                    broadcast='10.0.0.255',
                    prefixlen=24,
                    label='eth0:1')

        Configure p2p address on an interface::

            ip.addr('add', index=idx,
                    address='10.1.1.2',
                    mask=24,
                    local='10.1.1.1')
        '''

        flags_create = NLM_F_REQUEST | NLM_F_ACK | NLM_F_CREATE | NLM_F_EXCL
        commands = {'add': (RTM_NEWADDR, flags_create),
                    'del': (RTM_DELADDR, flags_create),
                    'remove': (RTM_DELADDR, flags_create),
                    'delete': (RTM_DELADDR, flags_create)}
        (command, flags) = commands.get(command, command)

        # fetch args
        index = index or kwarg.pop('index', 0)
        family = family or kwarg.pop('family', None)
        prefixlen = mask or kwarg.pop('mask', 0) or kwarg.pop('prefixlen', 0)
        scope = scope or kwarg.pop('scope', 0)

        # move address to kwarg
        # FIXME: add deprecation notice
        if address:
            kwarg['address'] = address

        # try to guess family, if it is not forced
        if kwarg.get('address') and family is None:
            if address.find(":") > -1:
                family = AF_INET6
                mask = mask or 128
            else:
                family = AF_INET
                mask = mask or 32

        # setup the message
        msg = ifaddrmsg()
        msg['index'] = index
        msg['family'] = family or 0
        msg['prefixlen'] = prefixlen
        msg['scope'] = scope

        # inject IFA_LOCAL, if family is AF_INET and IFA_LOCAL is not set
        if family == AF_INET and \
                kwarg.get('address') and \
                kwarg.get('local') is None:
            kwarg['local'] = kwarg['address']

        # patch broadcast, if needed
        if kwarg.get('broadcast') is True:
            kwarg['broadcast'] = getbroadcast(address, mask, family)

        # work on NLA
        for key in kwarg:
            nla = ifaddrmsg.name2nla(key)
            if kwarg[key] is not None:
                msg['attrs'].append([nla, kwarg[key]])

        ret = self.nlm_request(msg,
                               msg_type=command,
                               msg_flags=flags,
                               terminate=lambda x: x['header']['type'] ==
                               NLMSG_ERROR)
        if match:
            return self._match(match, ret)
        else:
            return ret

    def tc(self, command, kind=None, index=0, handle=0, **kwarg):
        '''
        "Swiss knife" for traffic control. With the method you can
        add, delete or modify qdiscs, classes and filters.

        * command -- add or delete qdisc, class, filter.
        * kind -- a string identifier -- "sfq", "htb", "u32" and so on.
        * handle -- integer or string

        Command can be one of ("add", "del", "add-class", "del-class",
        "add-filter", "del-filter") (see `commands` dict in the code).

        Handle notice: traditional iproute2 notation, like "1:0", actually
        represents two parts in one four-bytes integer::

            1:0    ->    0x10000
            1:1    ->    0x10001
            ff:0   ->   0xff0000
            ffff:1 -> 0xffff0001

        Target notice: if your target is a class/qdisc that applies an
        algorithm that can only apply to upstream traffic profile, but your
        keys variable explicitly references a match that is only relevant for
        upstream traffic, the kernel will reject the filter.  Unless you're
        dealing with devices like IMQs

        For pyroute2 tc() you can use both forms: integer like 0xffff0000
        or string like 'ffff:0000'. By default, handle is 0, so you can add
        simple classless queues w/o need to specify handle. Ingress queue
        causes handle to be 0xffff0000.

        So, to set up sfq queue on interface 1, the function call
        will be like that::

            ip = IPRoute()
            ip.tc("add", "sfq", 1)

        Instead of string commands ("add", "del"...), you can use also
        module constants, `RTM_NEWQDISC`, `RTM_DELQDISC` and so on::

            ip = IPRoute()
            flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_CREATE | NLM_F_EXCL
            ip.tc((RTM_NEWQDISC, flags), "sfq", 1)

        It should be noted that "change", "change-class" and
        "change-filter" work like "replace", "replace-class" and
        "replace-filter", except they will fail if the node doesn't
        exist (while it would have been created by "replace"). This is
        not the same behaviour as with "tc" where "change" can be used
        to modify the value of some options while leaving the others
        unchanged. However, as not all entities support this
        operation, we believe the "change" commands as implemented
        here are more useful.


        Also available "modules" (returns tc plugins dict) and "help"
        commands::

            help(ip.tc("modules")["htb"])
            print(ip.tc("help", "htb"))
        '''
        if command == 'modules':
            return tc_plugins

        if command == 'help':
            p = tc_plugins.get(kind)
            if p is not None and hasattr(p, '__doc__'):
                return p.__doc__
            else:
                return 'No help available'

        flags_base = NLM_F_REQUEST | NLM_F_ACK
        flags_make = flags_base | NLM_F_CREATE | NLM_F_EXCL
        flags_change = flags_base | NLM_F_REPLACE
        flags_replace = flags_change | NLM_F_CREATE

        commands = {'add': (RTM_NEWQDISC, flags_make),
                    'del': (RTM_DELQDISC, flags_make),
                    'remove': (RTM_DELQDISC, flags_make),
                    'delete': (RTM_DELQDISC, flags_make),
                    'change': (RTM_NEWQDISC, flags_change),
                    'replace': (RTM_NEWQDISC, flags_replace),
                    'add-class': (RTM_NEWTCLASS, flags_make),
                    'del-class': (RTM_DELTCLASS, flags_make),
                    'change-class': (RTM_NEWTCLASS, flags_change),
                    'replace-class': (RTM_NEWTCLASS, flags_replace),
                    'add-filter': (RTM_NEWTFILTER, flags_make),
                    'del-filter': (RTM_DELTFILTER, flags_make),
                    'change-filter': (RTM_NEWTFILTER, flags_change),
                    'replace-filter': (RTM_NEWTFILTER, flags_replace)}
        if isinstance(command, int):
            command = (command, flags_make)
        command, flags = commands.get(command, command)
        msg = tcmsg()
        # transform handle, parent and target, if needed:
        handle = transform_handle(handle)
        for item in ('parent', 'target', 'default'):
            if item in kwarg and kwarg[item] is not None:
                kwarg[item] = transform_handle(kwarg[item])
        msg['index'] = index
        msg['handle'] = handle
        opts = kwarg.get('opts', None)
        ##
        #
        #
        if kind in tc_plugins:
            p = tc_plugins[kind]
            msg['parent'] = kwarg.pop('parent', getattr(p, 'parent', 0))
            if hasattr(p, 'fix_msg'):
                p.fix_msg(msg, kwarg)
            if kwarg:
                if command in (RTM_NEWTCLASS, RTM_DELTCLASS):
                    opts = p.get_class_parameters(kwarg)
                else:
                    opts = p.get_parameters(kwarg)
        else:
            msg['parent'] = kwarg.get('parent', TC_H_ROOT)

        if kind is not None:
            msg['attrs'].append(['TCA_KIND', kind])
        if opts is not None:
            msg['attrs'].append(['TCA_OPTIONS', opts])
        return self.nlm_request(msg, msg_type=command, msg_flags=flags)

    def route(self, command, **kwarg):
        '''
        Route operations.

        Keywords to set up rtmsg fields:

        * dst_len, src_len -- destination and source mask(see `dst` below)
        * tos -- type of service
        * table -- routing table
        * proto -- `redirect`, `boot`, `static` (see `rt_proto`)
        * scope -- routing realm
        * type -- `unicast`, `local`, etc. (see `rt_type`)

        `pyroute2/netlink/rtnl/rtmsg.py` rtmsg.nla_map:

        * table -- routing table to use (default: 254)
        * gateway -- via address
        * prefsrc -- preferred source IP address
        * dst -- the same as `prefix`
        * src -- source address
        * iif -- incoming traffic interface
        * oif -- outgoing traffic interface

        etc.

        One can specify mask not as `dst_len`, but as a part of `dst`,
        e.g.: `dst="10.0.0.0/24"`.

        Commands:

        **add**

        Example::

            ip.route("add", dst="10.0.0.0/24", gateway="192.168.0.1")

        It is possible to set also route metrics. There are two ways
        to do so. The first is to use 'raw' NLA notation::

            ip.route("add",
                     dst="10.0.0.0",
                     mask=24,
                     gateway="192.168.0.1",
                     metrics={"attrs": [["RTAX_MTU", 1400],
                                        ["RTAX_HOPLIMIT", 16]]})

        The second way is to use shortcuts, provided by `IPRouteRequest`
        class, which is applied to `**kwarg` automatically::

            ip.route("add",
                     dst="10.0.0.0/24",
                     gateway="192.168.0.1",
                     metrics={"mtu": 1400,
                              "hoplimit": 16})

        ...

        More `route()` examples. Blackhole route::

            ip.route("add",
                     dst="10.0.0.0/24",
                     type="blackhole")

        Multipath route::

            ip.route("add",
                     dst="10.0.0.0/24",
                     multipath=[{"gateway": "192.168.0.1", "hops": 2},
                                {"gateway": "192.168.0.2", "hops": 1},
                                {"gateway": "192.168.0.3"}])

        MPLS lwtunnel on eth0::

            idx = ip.link_lookup(ifname='eth0')[0]
            ip.route("add",
                     dst="10.0.0.0/24",
                     oif=idx,
                     encap={"type": "mpls",
                            "labels": "200/300"})

        MPLS multipath::

            idx = ip.link_lookup(ifname='eth0')[0]
            ip.route("add",
                     dst="10.0.0.0/24",
                     table=20,
                     multipath=[{"gateway": "192.168.0.1",
                                 "encap": {"type": "mpls",
                                           "labels": 200}},
                                {"ifindex": idx,
                                 "encap": {"type": "mpls",
                                           "labels": 300}}])

        MPLS target can be int, string, dict or list::

            "labels": 300    # simple label
            "labels": "300"  # the same
            "labels": (200, 300)  # stacked
            "labels": "200/300"   # the same

            # explicit label definition
            "labels": {"bos": 1,
                       "label": 300,
                       "tc": 0,
                       "ttl": 16}

        **change**, **replace**

        Commands `change` and `replace` have the same meanings, as
        in ip-route(8): `change` modifies only existing route, while
        `replace` creates a new one, if there is no such route yet.

        **del**

        Remove the route. The same syntax as for **add**.

        **get**

        Get route by spec.

        **dump**

        Dump all routes.
        '''

        # 8<----------------------------------------------------
        # FIXME
        # flags should be moved to some more general place
        flags_dump = NLM_F_DUMP | NLM_F_REQUEST
        flags_base = NLM_F_REQUEST | NLM_F_ACK
        flags_make = flags_base | NLM_F_CREATE | NLM_F_EXCL
        flags_change = flags_base | NLM_F_REPLACE
        flags_replace = flags_change | NLM_F_CREATE
        # 8<----------------------------------------------------
        # transform kwarg

        if command in ('add', 'set', 'replace', 'change'):
            kwarg['proto'] = kwarg.get('proto', 'static') or 'static'
            kwarg['type'] = kwarg.get('type', 'unicast') or 'unicast'
        kwarg = IPRouteRequest(kwarg)
        if command in ('dump', 'show'):
            match = kwarg
        else:
            match = kwarg.pop('match', None)
        callback = kwarg.pop('callback', None)

        commands = {'add': (RTM_NEWROUTE, flags_make),
                    'set': (RTM_NEWROUTE, flags_replace),
                    'replace': (RTM_NEWROUTE, flags_replace),
                    'change': (RTM_NEWROUTE, flags_change),
                    'del': (RTM_DELROUTE, flags_make),
                    'remove': (RTM_DELROUTE, flags_make),
                    'delete': (RTM_DELROUTE, flags_make),
                    'get': (RTM_GETROUTE, NLM_F_REQUEST),
                    'show': (RTM_GETROUTE, flags_dump),
                    'dump': (RTM_GETROUTE, flags_dump)}
        (command, flags) = commands.get(command, command)
        msg = rtmsg()

        # table is mandatory; by default == 254
        # if table is not defined in kwarg, save it there
        # also for nla_attr:
        table = kwarg.get('table', 254)
        msg['table'] = table if table <= 255 else 252
        msg['family'] = kwarg.pop('family', AF_INET)
        msg['scope'] = kwarg.pop('scope', rt_scope['universe'])
        msg['dst_len'] = kwarg.pop('dst_len', None) or kwarg.pop('mask', 0)
        msg['src_len'] = kwarg.pop('src_len', 0)
        msg['tos'] = kwarg.pop('tos', 0)
        msg['flags'] = kwarg.pop('flags', 0)
        msg['type'] = kwarg.pop('type', rt_type['unspec'])
        msg['proto'] = kwarg.pop('proto', rt_proto['unspec'])
        msg['attrs'] = []

        if msg['family'] == AF_MPLS:
            for key in tuple(kwarg):
                if key not in ('dst', 'newdst', 'via', 'multipath', 'oif'):
                    kwarg.pop(key)

        for key in kwarg:
            nla = rtmsg.name2nla(key)
            if kwarg[key] is not None:
                msg['attrs'].append([nla, kwarg[key]])
                # fix IP family, if needed
                if msg['family'] == AF_UNSPEC:
                    if key in ('dst', 'src', 'gateway', 'prefsrc', 'newdst') \
                            and isinstance(kwarg[key], basestring):
                        msg['family'] = AF_INET6 if kwarg[key].find(':') >= 0 \
                            else AF_INET
                    elif key == 'multipath' and len(kwarg[key]) > 0:
                        hop = kwarg[key][0]
                        attrs = hop.get('attrs', [])
                        for attr in attrs:
                            if attr[0] == 'RTA_GATEWAY':
                                msg['family'] = AF_INET6 if \
                                    attr[1].find(':') >= 0 else AF_INET
                                break

        ret = self.nlm_request(msg,
                               msg_type=command,
                               msg_flags=flags,
                               callback=callback)
        if match:
            return self._match(match, ret)
        else:
            return ret

    def rule(self, command, *argv, **kwarg):
        '''
        Rule operations

            - command — add, delete
            - table — 0 < table id < 253
            - priority — 0 < rule's priority < 32766
            - action — type of rule, default 'FR_ACT_NOP' (see fibmsg.py)
            - rtscope — routing scope, default RT_SCOPE_UNIVERSE
                `(RT_SCOPE_UNIVERSE|RT_SCOPE_SITE|\
                RT_SCOPE_LINK|RT_SCOPE_HOST|RT_SCOPE_NOWHERE)`
            - family — rule's family (socket.AF_INET (default) or
                socket.AF_INET6)
            - src — IP source for Source Based (Policy Based) routing's rule
            - dst — IP for Destination Based (Policy Based) routing's rule
            - src_len — Mask for Source Based (Policy Based) routing's rule
            - dst_len — Mask for Destination Based (Policy Based) routing's
                rule
            - iifname — Input interface for Interface Based (Policy Based)
                routing's rule
            - oifname — Output interface for Interface Based (Policy Based)
                routing's rule

        All packets route via table 10::

            # 32000: from all lookup 10
            # ...
            ip.rule('add', table=10, priority=32000)

        Default action::

            # 32001: from all lookup 11 unreachable
            # ...
            iproute.rule('add',
                         table=11,
                         priority=32001,
                         action='FR_ACT_UNREACHABLE')

        Use source address to choose a routing table::

            # 32004: from 10.64.75.141 lookup 14
            # ...
            iproute.rule('add',
                         table=14,
                         priority=32004,
                         src='10.64.75.141')

        Use dst address to choose a routing table::

            # 32005: from 10.64.75.141/24 lookup 15
            # ...
            iproute.rule('add',
                         table=15,
                         priority=32005,
                         dst='10.64.75.141',
                         dst_len=24)

        Match fwmark::

            # 32006: from 10.64.75.141 fwmark 0xa lookup 15
            # ...
            iproute.rule('add',
                         table=15,
                         priority=32006,
                         dst='10.64.75.141',
                         fwmark=10)
        '''
        flags_base = NLM_F_REQUEST | NLM_F_ACK
        flags_make = flags_base | NLM_F_CREATE | NLM_F_EXCL
        flags_dump = NLM_F_REQUEST | NLM_F_ROOT | NLM_F_ATOMIC

        commands = {'add': (RTM_NEWRULE, flags_make),
                    'del': (RTM_DELRULE, flags_make),
                    'remove': (RTM_DELRULE, flags_make),
                    'delete': (RTM_DELRULE, flags_make),
                    'dump': (RTM_GETRULE, flags_dump)}
        if isinstance(command, int):
            command = (command, flags_make)
        command, flags = commands.get(command, command)

        if argv:
            # this code block will be removed in some release
            log.error('rule(): positional parameters are deprecated')
            names = ['table', 'priority', 'action', 'family',
                     'src', 'src_len', 'dst', 'dst_len', 'fwmark',
                     'iifname', 'oifname']
            kwarg.update(dict(zip(names, argv)))

        kwarg = IPRuleRequest(kwarg)
        msg = fibmsg()
        table = kwarg.get('table', 0)
        msg['table'] = table if table <= 255 else 252
        for key in ('family',
                    'src_len',
                    'dst_len',
                    'action',
                    'tos',
                    'flags'):
            msg[key] = kwarg.pop(key, 0)
        msg['attrs'] = []

        for key in kwarg:
            nla = fibmsg.name2nla(key)
            if kwarg[key] is not None:
                msg['attrs'].append([nla, kwarg[key]])

        ret = self.nlm_request(msg, msg_type=command, msg_flags=flags)

        if 'match' in kwarg:
            return self._match(kwarg['match'], ret)
        else:
            return ret
    # 8<---------------------------------------------------------------


class IPBatch(IPRouteMixin, IPBatchSocket):
    '''
    Netlink requests compiler. Does not send any requests, but
    instead stores them in the internal binary buffer. The
    contents of the buffer can be used to send batch requests,
    to test custom netlink parsers and so on.

    Uses `IPRouteMixin` and provides all the same API as normal
    `IPRoute` objects::

        # create the batch compiler
        ipb = IPBatch()
        # compile requests into the internal buffer
        ipb.link("add", index=550, ifname="test", kind="dummy")
        ipb.link("set", index=550, state="up")
        ipb.addr("add", index=550, address="10.0.0.2", mask=24)
        # save the buffer
        data = ipb.batch
        # reset the buffer
        ipb.reset()
        ...
        # send the buffer
        IPRoute().sendto(data, (0, 0))

    '''
    pass


class IPRoute(IPRouteMixin, IPRSocket):
    '''
    Public class that provides RTNL API to the current network
    namespace.
    '''
    pass


class RawIPRoute(IPRouteMixin, RawIPRSocket):
    '''
    The same as `IPRoute`, but does not use the netlink proxy.
    Thus it can not manage e.g. tun/tap interfaces.
    '''
    pass