Source code for pcapkit.protocols.internet.ipv6_frag
# -*- coding: utf-8 -*-
"""IPv6-Frag - Fragment Header for IPv6
==========================================
:mod:`pcapkit.protocols.internet.ipv6_frag` contains
:class:`~pcapkit.protocols.internet.ipv6_frag.IPv6_Frag`
only, which implements extractor for Fragment Header for
IPv6 (IPv6-Frag) [*]_, whose structure is described as
below:
======= ========= ==================== =======================
Octets Bits Name Description
======= ========= ==================== =======================
0 0 ``frag.next`` Next Header
1 8 Reserved
2 16 ``frag.offset`` Fragment Offset
3 29 Reserved
3 31 ``frag.mf`` More Flag
4 32 ``frag.id`` Identification
======= ========= ==================== =======================
.. [*] https://en.wikipedia.org/wiki/IPv6_packet#Fragment
"""
from typing import TYPE_CHECKING, overload
from pcapkit.const.reg.transtype import TransType as RegType_TransType
from pcapkit.protocols.data.internet.ipv6_frag import IPv6_Frag as DataType_IPv6_Frag
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__ = ['IPv6_Frag']
[docs]class IPv6_Frag(Internet[DataType_IPv6_Frag]):
"""This class implements Fragment Header for IPv6."""
##########################################################################
# Properties.
##########################################################################
@property
def name(self) -> 'Literal["Fragment Header for IPv6"]':
"""Name of current protocol."""
return 'Fragment Header for IPv6'
@property
def alias(self) -> 'Literal["IPv6-Frag"]':
"""Acronym of corresponding protocol."""
return 'IPv6-Frag'
@property
def length(self) -> 'Literal[8]':
"""Header length of current protocol."""
return 8
@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 self._next
@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, *, extension: 'bool' = False, # pylint: disable=arguments-differ
**kwargs: 'Any') -> 'DataType_IPv6_Frag': # pylint: disable=unused-argument
"""Read Fragment Header for IPv6.
Structure of IPv6-Frag header [:rfc:`8200`]:
.. code-block:: text
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Reserved | Fragment Offset |Res|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Args:
length: Length of packet data.
extension: If the packet 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)
_temp = self._read_fileng(1)
_offm = self._read_binary(2)
_ipid = self._read_unpack(4)
ipv6_frag = DataType_IPv6_Frag(
next=_next,
offset=int(_offm[:13], base=2),
mf=bool(int(_offm[15], base=2)),
id=_ipid,
)
if extension:
return ipv6_frag
return self._decode_next_layer(ipv6_frag, _next, length - self.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
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
extension: 'bool' = False, **kwargs: 'Any') -> 'None':
"""Post initialisation hook.
Args:
file: Source packet stream.
length: Length of packet data.
Keyword Args:
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[8]':
"""Return an estimated length for the object."""
return 8
[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.IPv6_Frag # type: ignore[return-value]
