Source code for pcapkit.protocols.internet.mh
# -*- coding: utf-8 -*-
# pylint: disable=fixme
"""mobility header
:mod:`pcapkit.protocols.internet.mh` contains
:class:`~pcapkit.protocols.internet.mh.MH` only,
which implements extractor for Mobility Header
(MH) [*]_, whose structure is described as below:
======= ========= ================== ===============================
Octets Bits Name Description
======= ========= ================== ===============================
0 0 ``mh.next`` Next Header
1 8 ``mh.length`` Header Length
2 16 ``mh.type`` Mobility Header Type
3 24 Reserved
4 32 ``mh.chksum`` Checksum
6 48 ``mh.data`` Message Data
======= ========= ================== ===============================
.. [*] https://en.wikipedia.org/wiki/Mobile_IP#Changes_in_IPv6_for_Mobile_IPv6
"""
# TODO: Implements extractor for message data of all MH types.
from typing import TYPE_CHECKING, overload
from pcapkit.const.mh.packet import Packet as RegType_Packet
from pcapkit.const.reg.transtype import TransType as RegType_TransType
from pcapkit.protocols.data.internet.mh import MH as DataType_MH
from pcapkit.protocols.internet.internet import Internet
from pcapkit.utilities.exceptions import UnsupportedCall
if TYPE_CHECKING:
from typing import Any, BinaryIO, NoReturn, Optional
from typing_extensions import Literal
from pcapkit.corekit.protochain import ProtoChain
from pcapkit.protocols.protocol import Protocol
__all__ = ['MH']
[docs]class MH(Internet[DataType_MH]):
"""This class implements Mobility Header."""
##########################################################################
# Properties.
##########################################################################
@property
def name(self) -> 'Literal["Mobility Header"]':
"""Name of current protocol."""
return 'Mobility Header'
@property
def length(self) -> 'int':
"""Header length of current protocol."""
return self._info.length
@property
def payload(self) -> 'Protocol | NoReturn':
"""Payload of current instance.
Raises:
UnsupportedCall: if the protocol is used as an IPv6 extension header
"""
if self._extf:
raise UnsupportedCall(f"'{self.__class__.__name__}' object has no attribute 'payload'")
return super().payload
@property
def protocol(self) -> 'Optional[str] | NoReturn':
"""Name of next layer protocol (if any).
Raises:
UnsupportedCall: if the protocol is used as an IPv6 extension header
"""
if self._extf:
raise UnsupportedCall(f"'{self.__class__.__name__}' object has no attribute 'protocol'")
return super().protocol
@property
def protochain(self) -> 'ProtoChain | NoReturn':
"""Protocol chain of current instance.
Raises:
UnsupportedCall: if the protocol is used as an IPv6 extension header
"""
if self._extf:
raise UnsupportedCall(f"'{self.__class__.__name__}' object has no attribute 'protochain'")
return super().protochain
##########################################################################
# Methods.
##########################################################################
[docs] def read(self, length: 'Optional[int]' = None, *, version: 'Literal[4, 6]' = 4, # pylint: disable=arguments-differ,unused-argument
extension: bool = False, **kwargs: 'Any') -> 'DataType_MH': # pylint: disable=unused-argument
"""Read Mobility Header.
Structure of MH header [:rfc:`6275`]:
.. code-block:: text
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Proto | Header Len | MH Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
. .
. Message Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Args:
length: Length of packet data.
version: IP protocol version.
extension: If the protocol is used as an IPv6 extension header.
**kwargs: Arbitrary keyword arguments.
Returns:
Parsed packet data.
"""
if length is None:
length = len(self)
_next = self._read_protos(1)
_hlen = self._read_unpack(1)
_type = self._read_unpack(1)
_temp = self._read_fileng(1)
_csum = self._read_fileng(2)
_data = self._read_fileng((_hlen+1)*8)
mh = DataType_MH(
next=_next,
length=(_hlen + 1) * 8,
type=RegType_Packet.get(_type),
chksum=_csum,
data=_data,
)
if extension:
return mh
return self._decode_next_layer(mh, _next, length - mh.length)
[docs] def make(self, **kwargs: 'Any') -> 'NoReturn':
"""Make (construct) packet data.
Args:
**kwargs: Arbitrary keyword arguments.
Returns:
Constructed packet data.
"""
raise NotImplementedError
##########################################################################
# Data models.
##########################################################################
@overload
def __post_init__(self, file: 'BinaryIO', length: 'Optional[int]' = ..., *, # pylint: disable=arguments-differ
version: 'Literal[4, 6]' = ..., extension: 'bool' = ...,
**kwargs: 'Any') -> 'None': ...
@overload
def __post_init__(self, **kwargs: 'Any') -> 'None': ... # pylint: disable=arguments-differ
[docs] def __post_init__(self, file: 'Optional[BinaryIO]' = None, length: 'Optional[int]' = None, *, # pylint: disable=arguments-differ
version: 'Literal[4, 6]' = 4, extension: 'bool' = False, # pylint: disable=unused-argument
**kwargs: 'Any') -> 'None':
"""Post initialisation hook.
Args:
file: Source packet stream.
length: Length of packet data.
version: IP protocol version.
extension: If the protocol is used as an IPv6 extension header.
**kwargs: Arbitrary keyword arguments.
See Also:
For construction argument, please refer to :meth:`make`.
"""
#: bool: If the protocol is used as an IPv6 extension header.
self._extf = extension
# call super __post_init__
super().__post_init__(file, length, extension=extension, **kwargs) # type: ignore[arg-type]
def __length_hint__(self) -> 'Literal[6]':
"""Return an estimated length for the object."""
return 6
[docs] @classmethod
def __index__(cls) -> 'RegType_TransType': # pylint: disable=invalid-index-returned
"""Numeral registry index of the protocol.
Returns:
Numeral registry index of the protocol in `IANA`_.
.. _IANA: https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml
"""
return RegType_TransType.Mobility_Header # type: ignore[return-value]
