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"""Module for serialization and deserialization of KNX/IP Header."""
from __future__ import annotations
from typing import Final
from xknx.exceptions import CouldNotParseKNXIP, IncompleteKNXIPFrame
from .body import KNXIPBody
from .knxip_enum import KNXIPServiceType
class KNXIPHeader:
"""Class for serialization and deserialization of KNX/IP Header."""
HEADERLENGTH: Final = 0x06
PROTOCOLVERSION: Final = 0x10 # The only valid protocol version at this time is 1.0
def __init__(self) -> None:
"""Initialize KNXIPHeader class."""
self.service_type_ident = KNXIPServiceType.ROUTING_INDICATION
self.total_length = 0 # to be set later
def from_knx(self, data: bytes) -> int:
"""Parse/deserialize from KNX/IP raw data."""
if len(data) < KNXIPHeader.HEADERLENGTH:
raise IncompleteKNXIPFrame("wrong connection header length")
if data[0] != KNXIPHeader.HEADERLENGTH:
raise CouldNotParseKNXIP("wrong connection header length")
# set immediately, as we need it for tcp stream parsing before raising exception
self.total_length = data[4] * 256 + data[5]
if data[1] != KNXIPHeader.PROTOCOLVERSION:
raise CouldNotParseKNXIP("wrong protocol version")
try:
self.service_type_ident = KNXIPServiceType(data[2] * 256 + data[3])
except ValueError:
raise CouldNotParseKNXIP(
f"KNXIPServiceType unknown: 0x{data[2:4].hex()}"
) from None
return KNXIPHeader.HEADERLENGTH
def set_length(self, body: KNXIPBody) -> None:
"""Set length of full KNX/IP packet from body + fixed header length."""
if not isinstance(body, KNXIPBody):
raise TypeError()
self.total_length = KNXIPHeader.HEADERLENGTH + body.calculated_length()
def to_knx(self) -> bytes:
"""Serialize to KNX/IP raw data."""
return (
bytes((KNXIPHeader.HEADERLENGTH, KNXIPHeader.PROTOCOLVERSION))
+ self.service_type_ident.value.to_bytes(2, "big")
+ self.total_length.to_bytes(2, "big")
)
def __repr__(self) -> str:
"""Return object as readable string."""
return (
"<KNXIPHeader "
f'HeaderLength="{KNXIPHeader.HEADERLENGTH}" '
f'ProtocolVersion="{KNXIPHeader.PROTOCOLVERSION}" '
f'KNXIPServiceType="{self.service_type_ident.name}" '
f'TotalLength="{self.total_length}" />'
)
def __eq__(self, other: object) -> bool:
"""Equal operator."""
return self.__dict__ == other.__dict__
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