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"""
Module for Serialization and Deserialization of KNX Session Authenticates.
The SESSION_AUTHENTICATE shall be sent by the KNXnet/IP secure client to the
control endpoint of the KNXnet/IP secure server after the Diffie-Hellman handshake
to authenticate the user against the server device.
"""
from __future__ import annotations
from typing import Final
from xknx.exceptions import CouldNotParseKNXIP
from .body import KNXIPBody
from .knxip_enum import KNXIPServiceType
class SessionAuthenticate(KNXIPBody):
"""Representation of a KNX Session Authenticate."""
SERVICE_TYPE = KNXIPServiceType.SESSION_AUTHENTICATE
LENGTH: Final = 18
def __init__(
self,
user_id: int = 0x02,
message_authentication_code: bytes = bytes(16),
) -> None:
"""Initialize SessionAuthenticate object."""
# 00h: Reserved, shall not be used
# 01h: Management level access
# 02h - 7Fh: User level access
# 80h - FFh: Reserved, shall not be used
# TODO: maybe use an Enum instead of int or raise an error in
# to_knx() and handle in RequestResponse class
self.user_id = user_id
self.message_authentication_code = message_authentication_code
def calculated_length(self) -> int:
"""Get length of KNX/IP body."""
return SessionAuthenticate.LENGTH
def from_knx(self, raw: bytes) -> int:
"""Parse/deserialize from KNX/IP raw data."""
if len(raw) != SessionAuthenticate.LENGTH:
raise CouldNotParseKNXIP("SessionAuthenticate has wrong length")
self.user_id = raw[1]
self.message_authentication_code = raw[2:]
return SessionAuthenticate.LENGTH
def to_knx(self) -> bytes:
"""Serialize to KNX/IP raw data."""
return (
bytes(
(
0x00, # reserved
self.user_id,
)
)
+ self.message_authentication_code
)
def __repr__(self) -> str:
"""Return object as readable string."""
return (
f"<SessionAuthenticate "
f'user_id="{self.user_id}" '
f'message_authentication_code="{self.message_authentication_code.hex()}" />'
)
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