# Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
#
# 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 abc
import struct

from . import packet_base
from . import packet_utils
from os_ken.lib import addrconv
from os_ken.lib import stringify

ICMPV6_DST_UNREACH = 1       # dest unreachable, codes:
ICMPV6_PACKET_TOO_BIG = 2       # packet too big
ICMPV6_TIME_EXCEEDED = 3       # time exceeded, code:
ICMPV6_PARAM_PROB = 4       # ip6 header bad

ICMPV6_ECHO_REQUEST = 128     # echo service
ICMPV6_ECHO_REPLY = 129     # echo reply
MLD_LISTENER_QUERY = 130     # multicast listener query
MLD_LISTENER_REPOR = 131     # multicast listener report
MLD_LISTENER_DONE = 132     # multicast listener done
MLDV2_LISTENER_REPORT = 143     # multicast listern report (v2)

# RFC2292 decls
ICMPV6_MEMBERSHIP_QUERY = 130     # group membership query
ICMPV6_MEMBERSHIP_REPORT = 131     # group membership report
ICMPV6_MEMBERSHIP_REDUCTION = 132     # group membership termination

ND_ROUTER_SOLICIT = 133     # router solicitation
ND_ROUTER_ADVERT = 134     # router advertisment
ND_NEIGHBOR_SOLICIT = 135     # neighbor solicitation
ND_NEIGHBOR_ADVERT = 136     # neighbor advertisment
ND_REDIREC = 137     # redirect

ICMPV6_ROUTER_RENUMBERING = 138     # router renumbering

ICMPV6_WRUREQUEST = 139     # who are you request
ICMPV6_WRUREPLY = 140     # who are you reply
ICMPV6_FQDN_QUERY = 139     # FQDN query
ICMPV6_FQDN_REPLY = 140     # FQDN reply
ICMPV6_NI_QUERY = 139     # node information request
ICMPV6_NI_REPLY = 140     # node information reply

ICMPV6_MAXTYPE = 201

# ND_OPTIONS from RFC 4861
ND_OPTION_SLA = 1  # Source Link-Layer Address
ND_OPTION_TLA = 2  # Target Link-Layer Address
ND_OPTION_PI = 3   # Prefix Information
ND_OPTION_RH = 4   # Redirected Header
ND_OPTION_MTU = 5  # MTU

MODE_IS_INCLUDE = 1
MODE_IS_EXCLUDE = 2
CHANGE_TO_INCLUDE_MODE = 3
CHANGE_TO_EXCLUDE_MODE = 4
ALLOW_NEW_SOURCES = 5
BLOCK_OLD_SOURCES = 6


class icmpv6(packet_base.PacketBase):
    r"""ICMPv6 (RFC 2463) header encoder/decoder class.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    type\_         Type
    code           Code
    csum           CheckSum
                   (0 means automatically-calculate when encoding)
    data           Payload.

                   os_ken.lib.packet.icmpv6.echo object, \
                   os_ken.lib.packet.icmpv6.nd_neighbor object, \
                   os_ken.lib.packet.icmpv6.nd_router_solicit object, \
                   os_ken.lib.packet.icmpv6.nd_router_advert object, \
                   os_ken.lib.packet.icmpv6.mld object, \
                   or a bytearray.
    ============== ====================
    """
    _PACK_STR = '!BBH'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _ICMPV6_TYPES = {}

    @staticmethod
    def register_icmpv6_type(*args):
        def _register_icmpv6_type(cls):
            for type_ in args:
                icmpv6._ICMPV6_TYPES[type_] = cls
            return cls
        return _register_icmpv6_type

    def __init__(self, type_=0, code=0, csum=0, data=b''):
        super(icmpv6, self).__init__()
        self.type_ = type_
        self.code = code
        self.csum = csum
        self.data = data

    @classmethod
    def parser(cls, buf):
        (type_, code, csum) = struct.unpack_from(cls._PACK_STR, buf)
        msg = cls(type_, code, csum)
        offset = cls._MIN_LEN
        if len(buf) > offset:
            cls_ = cls._ICMPV6_TYPES.get(type_, None)
            if cls_:
                msg.data = cls_.parser(buf, offset)
            else:
                msg.data = buf[offset:]

        return msg, None, None

    def serialize(self, payload, prev):
        hdr = bytearray(struct.pack(icmpv6._PACK_STR, self.type_,
                                    self.code, self.csum))

        if self.data:
            if self.type_ in icmpv6._ICMPV6_TYPES:
                assert isinstance(self.data, _ICMPv6Payload)
                hdr += self.data.serialize()
            else:
                hdr += self.data
        if self.csum == 0:
            self.csum = packet_utils.checksum_ip(prev, len(hdr), hdr + payload)
            struct.pack_into('!H', hdr, 2, self.csum)

        return hdr

    def __len__(self):
        return self._MIN_LEN + len(self.data)


class _ICMPv6Payload(stringify.StringifyMixin, metaclass=abc.ABCMeta):
    """
    Base class for the payload of ICMPv6 packet.
    """


@icmpv6.register_icmpv6_type(ND_NEIGHBOR_SOLICIT, ND_NEIGHBOR_ADVERT)
class nd_neighbor(_ICMPv6Payload):
    """ICMPv6 sub encoder/decoder class for Neighbor Solicitation and
    Neighbor Advertisement messages. (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.icmpv6.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    res            R,S,O Flags for Neighbor Advertisement. \
                   The 3 MSBs of "Reserved" field for Neighbor Solicitation.
    dst            Target Address
    option         a derived object of os_ken.lib.packet.icmpv6.nd_option \
                   or a bytearray. None if no options.
    ============== ====================
    """

    _PACK_STR = '!I16s'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _ND_OPTION_TYPES = {}
    _TYPE = {
        'ascii': [
            'dst'
        ]
    }

    @staticmethod
    def register_nd_option_type(*args):
        def _register_nd_option_type(cls):
            nd_neighbor._ND_OPTION_TYPES[cls.option_type()] = cls
            return cls
        return _register_nd_option_type(args[0])

    def __init__(self, res=0, dst='::', option=None):
        self.res = res
        self.dst = dst
        self.option = option

    @classmethod
    def parser(cls, buf, offset):
        (res, dst) = struct.unpack_from(cls._PACK_STR, buf, offset)
        offset += cls._MIN_LEN
        option = None
        if len(buf) > offset:
            (type_, length) = struct.unpack_from('!BB', buf, offset)
            if length == 0:
                raise struct.error('Invalid length: {len}'.format(len=length))
            cls_ = cls._ND_OPTION_TYPES.get(type_)
            if cls_ is not None:
                option = cls_.parser(buf, offset)
            else:
                option = buf[offset:]
        msg = cls(res >> 29, addrconv.ipv6.bin_to_text(dst), option)
        return msg

    def serialize(self):
        res = self.res << 29
        hdr = bytearray(struct.pack(
            nd_neighbor._PACK_STR, res,
            addrconv.ipv6.text_to_bin(self.dst)))
        if self.option is not None:
            if isinstance(self.option, nd_option):
                hdr.extend(self.option.serialize())
            else:
                hdr.extend(self.option)
        return bytes(hdr)

    def __len__(self):
        length = self._MIN_LEN
        if self.option is not None:
            length += len(self.option)
        return length


@icmpv6.register_icmpv6_type(ND_ROUTER_SOLICIT)
class nd_router_solicit(_ICMPv6Payload):
    """ICMPv6 sub encoder/decoder class for Router Solicitation messages.
    (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.icmpv6.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    res            This field is unused.  It MUST be initialized to zero.
    option         a derived object of os_ken.lib.packet.icmpv6.nd_option \
                   or a bytearray. None if no options.
    ============== ====================
    """

    _PACK_STR = '!I'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _ND_OPTION_TYPES = {}

    @staticmethod
    def register_nd_option_type(*args):
        def _register_nd_option_type(cls):
            nd_router_solicit._ND_OPTION_TYPES[cls.option_type()] = cls
            return cls
        return _register_nd_option_type(args[0])

    def __init__(self, res=0, option=None):
        self.res = res
        self.option = option

    @classmethod
    def parser(cls, buf, offset):
        (res, ) = struct.unpack_from(cls._PACK_STR, buf, offset)
        offset += cls._MIN_LEN
        option = None
        if len(buf) > offset:
            (type_, length) = struct.unpack_from('!BB', buf, offset)
            if length == 0:
                raise struct.error('Invalid length: {len}'.format(len=length))
            cls_ = cls._ND_OPTION_TYPES.get(type_)
            if cls_ is not None:
                option = cls_.parser(buf, offset)
            else:
                option = buf[offset:]
        msg = cls(res, option)
        return msg

    def serialize(self):
        hdr = bytearray(struct.pack(
            nd_router_solicit._PACK_STR, self.res))
        if self.option is not None:
            if isinstance(self.option, nd_option):
                hdr.extend(self.option.serialize())
            else:
                hdr.extend(self.option)
        return bytes(hdr)

    def __len__(self):
        length = self._MIN_LEN
        if self.option is not None:
            length += len(self.option)
        return length


@icmpv6.register_icmpv6_type(ND_ROUTER_ADVERT)
class nd_router_advert(_ICMPv6Payload):
    """ICMPv6 sub encoder/decoder class for Router Advertisement messages.
    (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.icmpv6.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    ch_l           Cur Hop Limit.
    res            M,O Flags for Router Advertisement.
    rou_l          Router Lifetime.
    rea_t          Reachable Time.
    ret_t          Retrans Timer.
    options        List of a derived object of \
                   os_ken.lib.packet.icmpv6.nd_option or a bytearray. \
                   None if no options.
    ============== ====================
    """

    _PACK_STR = '!BBHII'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _ND_OPTION_TYPES = {}

    @staticmethod
    def register_nd_option_type(*args):
        def _register_nd_option_type(cls):
            nd_router_advert._ND_OPTION_TYPES[cls.option_type()] = cls
            return cls
        return _register_nd_option_type(args[0])

    def __init__(self, ch_l=0, res=0, rou_l=0, rea_t=0, ret_t=0, options=None):
        self.ch_l = ch_l
        self.res = res
        self.rou_l = rou_l
        self.rea_t = rea_t
        self.ret_t = ret_t
        options = options or []
        assert isinstance(options, list)
        self.options = options

    @classmethod
    def parser(cls, buf, offset):
        (ch_l, res, rou_l, rea_t, ret_t
         ) = struct.unpack_from(cls._PACK_STR, buf, offset)
        offset += cls._MIN_LEN
        options = []
        while len(buf) > offset:
            (type_, length) = struct.unpack_from('!BB', buf, offset)
            if length == 0:
                raise struct.error('Invalid length: {len}'.format(len=length))
            cls_ = cls._ND_OPTION_TYPES.get(type_)
            if cls_ is not None:
                option = cls_.parser(buf, offset)
            else:
                option = buf[offset:offset + (length * 8)]
            options.append(option)
            offset += len(option)
        msg = cls(ch_l, res >> 6, rou_l, rea_t, ret_t, options)
        return msg

    def serialize(self):
        res = self.res << 6
        hdr = bytearray(struct.pack(
            nd_router_advert._PACK_STR, self.ch_l, res, self.rou_l,
            self.rea_t, self.ret_t))
        for option in self.options:
            if isinstance(option, nd_option):
                hdr.extend(option.serialize())
            else:
                hdr.extend(option)
        return bytes(hdr)

    def __len__(self):
        length = self._MIN_LEN
        for option in self.options:
            length += len(option)
        return length


class nd_option(stringify.StringifyMixin, metaclass=abc.ABCMeta):
    @classmethod
    @abc.abstractmethod
    def option_type(cls):
        pass

    @abc.abstractmethod
    def __init__(self, _type, length):
        self._type = _type
        self.length = length

    @classmethod
    @abc.abstractmethod
    def parser(cls, buf):
        pass

    @abc.abstractmethod
    def serialize(self):
        pass

    def __len__(self):
        return self._MIN_LEN


class nd_option_la(nd_option):

    _PACK_STR = '!BB6s'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _TYPE = {
        'ascii': [
            'hw_src'
        ]
    }

    @abc.abstractmethod
    def __init__(self, length, hw_src, data):
        super(nd_option_la, self).__init__(self.option_type(), length)
        self.hw_src = hw_src
        self.data = data

    @classmethod
    def parser(cls, buf, offset):
        (_, length, hw_src) = struct.unpack_from(cls._PACK_STR, buf, offset)
        msg = cls(length, addrconv.mac.bin_to_text(hw_src))
        offset += cls._MIN_LEN
        if len(buf) > offset:
            msg.data = buf[offset:]

        return msg

    def serialize(self):
        buf = bytearray(struct.pack(
            self._PACK_STR, self.option_type(), self.length,
            addrconv.mac.text_to_bin(self.hw_src)))
        if self.data is not None:
            buf.extend(self.data)
        mod = len(buf) % 8
        if mod:
            buf.extend(bytearray(8 - mod))
        if 0 == self.length:
            self.length = len(buf) // 8
            struct.pack_into('!B', buf, 1, self.length)
        return bytes(buf)

    def __len__(self):
        length = self._MIN_LEN
        if self.data is not None:
            length += len(self.data)
        return length


@nd_neighbor.register_nd_option_type
@nd_router_solicit.register_nd_option_type
@nd_router_advert.register_nd_option_type
class nd_option_sla(nd_option_la):
    """ICMPv6 sub encoder/decoder class for Neighbor discovery
    Source Link-Layer Address Option. (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.nd_neighbor,
    os_ken.lib.packet.icmpv6.nd_router_solicit or
    os_ken.lib.packet.icmpv6.nd_router_advert.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    length         length of the option. \
                   (0 means automatically-calculate when encoding)
    hw_src         Link-Layer Address. \
                   NOTE: If the address is longer than 6 octets this contains \
                   the first 6 octets in the address. \
                   This implementation assumes the address has at least \
                   6 octets.
    data           A bytearray which contains the rest of Link-Layer Address \
                   and padding.  When encoding a packet, it's user's \
                   responsibility to provide necessary padding for 8-octets \
                   alignment required by the protocol.
    ============== ====================
    """

    @classmethod
    def option_type(cls):
        return ND_OPTION_SLA

    def __init__(self, length=0, hw_src='00:00:00:00:00:00', data=None):
        super(nd_option_sla, self).__init__(length, hw_src, data)


@nd_neighbor.register_nd_option_type
class nd_option_tla(nd_option_la):
    """ICMPv6 sub encoder/decoder class for Neighbor discovery
    Target Link-Layer Address Option. (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.nd_neighbor.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    length         length of the option. \
                   (0 means automatically-calculate when encoding)
    hw_src         Link-Layer Address. \
                   NOTE: If the address is longer than 6 octets this contains \
                   the first 6 octets in the address. \
                   This implementation assumes the address has at least \
                   6 octets.
    data           A bytearray which contains the rest of Link-Layer Address \
                   and padding.  When encoding a packet, it's user's \
                   responsibility to provide necessary padding for 8-octets \
                   alignment required by the protocol.
    ============== ====================
    """

    @classmethod
    def option_type(cls):
        return ND_OPTION_TLA

    def __init__(self, length=0, hw_src='00:00:00:00:00:00', data=None):
        super(nd_option_tla, self).__init__(length, hw_src, data)


@nd_router_advert.register_nd_option_type
class nd_option_pi(nd_option):
    r"""ICMPv6 sub encoder/decoder class for Neighbor discovery
    Prefix Information Option. (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.nd_router_advert.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    length         length of the option. \
                   (0 means automatically-calculate when encoding)
    pl             Prefix Length.
    res1           L,A,R\* Flags for Prefix Information.
    val_l          Valid Lifetime.
    pre_l          Preferred Lifetime.
    res2           This field is unused. It MUST be initialized to zero.
    prefix         An IP address or a prefix of an IP address.
    ============== ====================

    \*R flag is defined in (RFC 3775)
    """

    _PACK_STR = '!BBBBIII16s'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _TYPE = {
        'ascii': [
            'prefix'
        ]
    }

    @classmethod
    def option_type(cls):
        return ND_OPTION_PI

    def __init__(self, length=0, pl=0, res1=0, val_l=0, pre_l=0, res2=0,
                 prefix='::'):
        super(nd_option_pi, self).__init__(self.option_type(), length)
        self.pl = pl
        self.res1 = res1
        self.val_l = val_l
        self.pre_l = pre_l
        self.res2 = res2
        self.prefix = prefix

    @classmethod
    def parser(cls, buf, offset):
        (_, length, pl, res1, val_l, pre_l, res2, prefix
         ) = struct.unpack_from(cls._PACK_STR, buf, offset)
        msg = cls(length, pl, res1 >> 5, val_l, pre_l, res2,
                  addrconv.ipv6.bin_to_text(prefix))

        return msg

    def serialize(self):
        res1 = self.res1 << 5
        hdr = bytearray(struct.pack(
            self._PACK_STR, self.option_type(), self.length, self.pl,
            res1, self.val_l, self.pre_l, self.res2,
            addrconv.ipv6.text_to_bin(self.prefix)))
        if 0 == self.length:
            self.length = len(hdr) // 8
            struct.pack_into('!B', hdr, 1, self.length)
        return bytes(hdr)


@nd_router_advert.register_nd_option_type
class nd_option_mtu(nd_option):
    """ICMPv6 sub encoder/decoder class for Neighbor discovery
    MTU Option. (RFC 4861)

    This is used with os_ken.lib.packet.icmpv6.nd_router_advert.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    .. tabularcolumns:: |l|p{35em}|

    ============== ====================
    Attribute      Description
    ============== ====================
    mtu            MTU.
    ============== ====================
    """

    _PACK_STR = '!BBHI'
    _LEN = struct.calcsize(_PACK_STR)
    _OPTION_LEN = _LEN // 8

    @classmethod
    def option_type(cls):
        return ND_OPTION_MTU

    def __init__(self, mtu=1500):
        super(nd_option_mtu, self).__init__(self.option_type(), 0)
        self.mtu = mtu

    @classmethod
    def parser(cls, buf, offset):
        (_, _, _, mtu) = struct.unpack_from(cls._PACK_STR, buf, offset)
        msg = cls(mtu)
        return msg

    def serialize(self):
        buf = bytearray(struct.pack(
            self._PACK_STR, self.option_type(), self._OPTION_LEN, 0, self.mtu))
        return bytes(buf)


@icmpv6.register_icmpv6_type(ICMPV6_ECHO_REPLY, ICMPV6_ECHO_REQUEST)
class echo(_ICMPv6Payload):
    """ICMPv6 sub encoder/decoder class for Echo Request and Echo Reply
    messages.

    This is used with os_ken.lib.packet.icmpv6.icmpv6 for
    ICMPv6 Echo Request and Echo Reply messages.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    ============== ====================
    Attribute      Description
    ============== ====================
    id             Identifier
    seq            Sequence Number
    data           Data
    ============== ====================
    """

    _PACK_STR = '!HH'
    _MIN_LEN = struct.calcsize(_PACK_STR)

    def __init__(self, id_=0, seq=0, data=None):
        self.id = id_
        self.seq = seq
        self.data = data

    @classmethod
    def parser(cls, buf, offset):
        (id_, seq) = struct.unpack_from(cls._PACK_STR, buf, offset)
        msg = cls(id_, seq)
        offset += cls._MIN_LEN

        if len(buf) > offset:
            msg.data = buf[offset:]

        return msg

    def serialize(self):
        hdr = bytearray(struct.pack(echo._PACK_STR, self.id,
                                    self.seq))
        if self.data is not None:
            hdr += bytearray(self.data)

        return hdr

    def __len__(self):
        length = self._MIN_LEN
        if self.data is not None:
            length += len(self.data)
        return length


@icmpv6.register_icmpv6_type(
    MLD_LISTENER_QUERY, MLD_LISTENER_REPOR, MLD_LISTENER_DONE)
class mld(_ICMPv6Payload):
    """ICMPv6 sub encoder/decoder class for MLD Lister Query,
    MLD Listener Report, and MLD Listener Done messages. (RFC 2710)

    http://www.ietf.org/rfc/rfc2710.txt

    This is used with os_ken.lib.packet.icmpv6.icmpv6.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    ============== =========================================
    Attribute      Description
    ============== =========================================
    maxresp        max response time in millisecond. it is
                   meaningful only in Query Message.
    address        a group address value.
    ============== =========================================
    """

    _PACK_STR = '!H2x16s'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _TYPE = {
        'ascii': [
            'address'
        ]
    }

    def __init__(self, maxresp=0, address='::'):
        self.maxresp = maxresp
        self.address = address

    @classmethod
    def parser(cls, buf, offset):
        if cls._MIN_LEN < len(buf[offset:]):
            msg = mldv2_query.parser(buf[offset:])
        else:
            (maxresp, address) = struct.unpack_from(
                cls._PACK_STR, buf, offset)
            msg = cls(maxresp, addrconv.ipv6.bin_to_text(address))

        return msg

    def serialize(self):
        buf = struct.pack(mld._PACK_STR, self.maxresp,
                          addrconv.ipv6.text_to_bin(self.address))
        return buf

    def __len__(self):
        return self._MIN_LEN


class mldv2_query(mld):
    """
    ICMPv6 sub encoder/decoder class for MLD v2 Lister Query messages.
    (RFC 3810)

    http://www.ietf.org/rfc/rfc3810.txt

    This is used with os_ken.lib.packet.icmpv6.icmpv6.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    ============== =========================================
    Attribute      Description
    ============== =========================================
    maxresp        max response time in millisecond. it is
                   meaningful only in Query Message.
    address        a group address value.
    s_flg          when set to 1, routers suppress the timer
                   process.
    qrv            robustness variable for a querier.
    qqic           an interval time for a querier in unit of
                   seconds.
    num            a number of the multicast servers.
    srcs           a list of IPv6 addresses of the multicast
                   servers.
    ============== =========================================
    """

    _PACK_STR = '!H2x16sBBH'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _TYPE = {
        'ascii': [
            'address'
        ],
        'asciilist': [
            'srcs'
        ]
    }

    def __init__(self, maxresp=0, address='::', s_flg=0, qrv=2,
                 qqic=0, num=0, srcs=None):
        super(mldv2_query, self).__init__(maxresp, address)
        self.s_flg = s_flg
        self.qrv = qrv
        self.qqic = qqic
        self.num = num
        srcs = srcs or []
        assert isinstance(srcs, list)
        for src in srcs:
            assert isinstance(src, str)
        self.srcs = srcs

    @classmethod
    def parser(cls, buf):
        (maxresp, address, s_qrv, qqic, num
         ) = struct.unpack_from(cls._PACK_STR, buf)
        s_flg = (s_qrv >> 3) & 0b1
        qrv = s_qrv & 0b111
        offset = cls._MIN_LEN
        srcs = []
        while 0 < len(buf[offset:]) and num > len(srcs):
            assert 16 <= len(buf[offset:])
            (src, ) = struct.unpack_from('16s', buf, offset)
            srcs.append(addrconv.ipv6.bin_to_text(src))
            offset += 16
        assert num == len(srcs)
        return cls(maxresp, addrconv.ipv6.bin_to_text(address), s_flg,
                   qrv, qqic, num, srcs)

    def serialize(self):
        s_qrv = self.s_flg << 3 | self.qrv
        buf = bytearray(struct.pack(self._PACK_STR, self.maxresp,
                                    addrconv.ipv6.text_to_bin(self.address), s_qrv,
                                    self.qqic, self.num))
        for src in self.srcs:
            buf.extend(struct.pack('16s', addrconv.ipv6.text_to_bin(src)))
        if 0 == self.num:
            self.num = len(self.srcs)
            struct.pack_into('!H', buf, 22, self.num)
        return bytes(buf)

    def __len__(self):
        return self._MIN_LEN + len(self.srcs) * 16


@icmpv6.register_icmpv6_type(MLDV2_LISTENER_REPORT)
class mldv2_report(mld):
    """
    ICMPv6 sub encoder/decoder class for MLD v2 Lister Report messages.
    (RFC 3810)

    http://www.ietf.org/rfc/rfc3810.txt

    This is used with os_ken.lib.packet.icmpv6.icmpv6.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte order.
    __init__ takes the corresponding args in this order.

    ============== =========================================
    Attribute      Description
    ============== =========================================
    record_num     a number of the group records.
    records        a list of os_ken.lib.packet.icmpv6.mldv2_report_group.
                   None if no records.
    ============== =========================================
    """

    _PACK_STR = '!2xH'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _class_prefixes = ['mldv2_report_group']

    def __init__(self, record_num=0, records=None):
        self.record_num = record_num
        records = records or []
        assert isinstance(records, list)
        for record in records:
            assert isinstance(record, mldv2_report_group)
        self.records = records

    @classmethod
    def parser(cls, buf, offset):
        (record_num, ) = struct.unpack_from(cls._PACK_STR, buf, offset)
        offset += cls._MIN_LEN
        records = []
        while 0 < len(buf[offset:]) and record_num > len(records):
            record = mldv2_report_group.parser(buf[offset:])
            records.append(record)
            offset += len(record)
        assert record_num == len(records)
        return cls(record_num, records)

    def serialize(self):
        buf = bytearray(struct.pack(self._PACK_STR, self.record_num))
        for record in self.records:
            buf.extend(record.serialize())
        if 0 == self.record_num:
            self.record_num = len(self.records)
            struct.pack_into('!H', buf, 2, self.record_num)
        return bytes(buf)

    def __len__(self):
        records_len = 0
        for record in self.records:
            records_len += len(record)
        return self._MIN_LEN + records_len


class mldv2_report_group(stringify.StringifyMixin):
    r"""
    ICMPv6 sub encoder/decoder class for MLD v2 Lister Report Group
    Record messages. (RFC 3810)

    This is used with os_ken.lib.packet.icmpv6.mldv2_report.

    An instance has the following attributes at least.
    Most of them are same to the on-wire counterparts but in host byte
    order.
    __init__ takes the corresponding args in this order.

    =============== ====================================================
    Attribute       Description
    =============== ====================================================
    type\_          a group record type for v3.
    aux_len         the length of the auxiliary data in 32-bit words.
    num             a number of the multicast servers.
    address         a group address value.
    srcs            a list of IPv6 addresses of the multicast servers.
    aux             the auxiliary data.
    =============== ====================================================
    """
    _PACK_STR = '!BBH16s'
    _MIN_LEN = struct.calcsize(_PACK_STR)
    _TYPE = {
        'ascii': [
            'address'
        ],
        'asciilist': [
            'srcs'
        ]
    }

    def __init__(self, type_=0, aux_len=0, num=0, address='::',
                 srcs=None, aux=None):
        self.type_ = type_
        self.aux_len = aux_len
        self.num = num
        self.address = address
        srcs = srcs or []
        assert isinstance(srcs, list)
        for src in srcs:
            assert isinstance(src, str)
        self.srcs = srcs
        self.aux = aux

    @classmethod
    def parser(cls, buf):
        (type_, aux_len, num, address
         ) = struct.unpack_from(cls._PACK_STR, buf)
        offset = cls._MIN_LEN
        srcs = []
        while 0 < len(buf[offset:]) and num > len(srcs):
            assert 16 <= len(buf[offset:])
            (src, ) = struct.unpack_from('16s', buf, offset)
            srcs.append(addrconv.ipv6.bin_to_text(src))
            offset += 16
        assert num == len(srcs)
        aux = None
        if aux_len:
            (aux, ) = struct.unpack_from('%ds' % (aux_len * 4), buf, offset)
        msg = cls(type_, aux_len, num, addrconv.ipv6.bin_to_text(address),
                  srcs, aux)
        return msg

    def serialize(self):
        buf = bytearray(struct.pack(self._PACK_STR, self.type_,
                                    self.aux_len, self.num,
                                    addrconv.ipv6.text_to_bin(self.address)))
        for src in self.srcs:
            buf.extend(struct.pack('16s', addrconv.ipv6.text_to_bin(src)))
        if 0 == self.num:
            self.num = len(self.srcs)
            struct.pack_into('!H', buf, 2, self.num)
        if self.aux is not None:
            mod = len(self.aux) % 4
            if mod:
                self.aux += bytearray(4 - mod)
                self.aux = bytes(self.aux)
            buf.extend(self.aux)
            if 0 == self.aux_len:
                self.aux_len = len(self.aux) // 4
                struct.pack_into('!B', buf, 1, self.aux_len)
        return bytes(buf)

    def __len__(self):
        return self._MIN_LEN + len(self.srcs) * 16 + self.aux_len * 4


icmpv6.set_classes(icmpv6._ICMPV6_TYPES)
nd_neighbor.set_classes(nd_neighbor._ND_OPTION_TYPES)
nd_router_solicit.set_classes(nd_router_solicit._ND_OPTION_TYPES)
nd_router_advert.set_classes(nd_router_advert._ND_OPTION_TYPES)