Source code for pcapkit.protocols.transport.udp
# -*- coding: utf-8 -*-
"""UDP - User Datagram Protocol
==================================
:mod:`pcapkit.protocols.transport.udp` contains
:class:`~pcapkit.protocols.transport.udp.UDP` only,
which implements extractor for User Datagram Protocol
(UDP) [*]_, whose structure is described as below:
======= ========= ===================== ===============================
Octets Bits Name Description
======= ========= ===================== ===============================
0 0 ``udp.srcport`` Source Port
2 16 ``udp.dstport`` Destination Port
4 32 ``udp.len`` Length (header includes)
6 48 ``udp.checksum`` Checksum
======= ========= ===================== ===============================
.. [*] https://en.wikipedia.org/wiki/User_Datagram_Protocol
"""
import collections
from typing import TYPE_CHECKING
from pcapkit.const.reg.transtype import TransType as RegType_TransType
from pcapkit.protocols.data.transport.udp import UDP as DataType_UDP
from pcapkit.protocols.transport.transport import Transport
if TYPE_CHECKING:
from typing import Any, NoReturn, Optional
from typing_extensions import Literal
__all__ = ['UDP']
[docs]class UDP(Transport[DataType_UDP]):
"""This class implements User Datagram Protocol.
This class currently supports parsing of the following protocols, which are
registered in the :attr:`self.__proto__ <pcapkit.protocols.transport.udp.UDP.__proto__>`
attribute:
.. list-table::
:header-rows: 1
* - Port Number
- Protocol
* - 80
- :class:`pcapkit.protocols.application.http.HTTP`
"""
##########################################################################
# Defaults.
##########################################################################
#: DefaultDict[int, tuple[str, str]]: Protocol index mapping for decoding next layer,
#: c.f. :meth:`self._decode_next_layer <pcapkit.protocols.transport.transport.Transport._decode_next_layer>`
#: & :meth:`self._import_next_layer <pcapkit.protocols.protocol.Protocol._import_next_layer>`.
__proto__ = collections.defaultdict(
lambda: ('pcapkit.protocols.misc.raw', 'Raw'),
{
80: ('pcapkit.protocols.application.http', 'HTTP'), # HTTP
},
)
##########################################################################
# Properties.
##########################################################################
@property
def name(self) -> 'Literal["User Datagram Protocol"]':
"""Name of current protocol."""
return 'User Datagram Protocol'
@property
def length(self) -> 'Literal[8]':
"""Header length of current protocol."""
return 8
@property
def src(self) -> 'int':
"""Source port."""
return self._info.srcport
@property
def dst(self) -> 'int':
"""Destination port."""
return self._info.dstport
##########################################################################
# Methods.
##########################################################################
[docs] def read(self, length: 'Optional[int]' = None, **kwargs: 'Any') -> 'DataType_UDP': # pylint: disable=unused-argument
"""Read User Datagram Protocol (UDP).
Structure of UDP header [:rfc:`768`]:
.. code-block:: text
0 7 8 15 16 23 24 31
+--------+--------+--------+--------+
| Source | Destination |
| Port | Port |
+--------+--------+--------+--------+
| | |
| Length | Checksum |
+--------+--------+--------+--------+
|
| data octets ...
+---------------- ...
Args:
length: Length of packet data.
**kwargs: Arbitrary keyword arguments.
Returns:
Parsed packet data.
"""
if length is None:
length = len(self)
_srcp = self._read_unpack(2)
_dstp = self._read_unpack(2)
_tlen = self._read_unpack(2)
_csum = self._read_fileng(2)
udp = DataType_UDP(
srcport=_srcp,
dstport=_dstp,
len=_tlen,
checksum=_csum,
)
return self._decode_next_layer(udp, (udp.srcport, udp.dstport), udp.len - 8)
[docs] def make(self, **kwargs: 'Any') -> 'NoReturn':
"""Make (construct) packet data.
Args:
**kwargs: Arbitrary keyword arguments.
Returns:
Constructed packet data.
"""
raise NotImplementedError
##########################################################################
# Data models.
##########################################################################
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.UDP # type: ignore[return-value]