Ryan Malloy
9a024181ae
Project scaffold (uv, pyproject.toml CalVer 2026.5.10, ruff, pytest, mypy
strict config, MIT, README, .gitignore protecting any .pca / panel keys).
Library primitives (src/omni_pca/):
- crypto.py AES-128-ECB + per-block XOR seq pre-whitening, session-key
derivation (CK[0:11] || (CK[11:16] XOR SessionID))
- opcodes.py Byte-exact PacketType (12), v1 MessageType (104),
v2 MessageType (83), ConnectionType, ProtocolVersion
- packet.py Outer Packet dataclass with encode/decode
- message.py Inner Message + CRC-16/MODBUS, helpers for v1/v2
- pca_file.py Borland LCG XOR cipher, PcaReader, .pca + .CFG parsers
(KEY_PC01 = 0x14326573, KEY_EXPORT = 0x17569237 — fixed
from initial typo; verified via test_keys_match_decompiled)
- __main__.py CLI: 'omni-pca decode-pca <file> --field {host,port,...}'
PII opt-in via --include-pii
49 tests pass, 1 skipped (live fixture). Ruff clean.
106 lines
3.3 KiB
Python
106 lines
3.3 KiB
Python
"""Unit tests for omni_pca.message."""
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from __future__ import annotations
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import pytest
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from omni_pca.message import (
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START_CHAR_V1_ADDRESSABLE,
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START_CHAR_V1_UNADDRESSED,
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START_CHAR_V2,
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Message,
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MessageCrcError,
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MessageFormatError,
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crc16_modbus,
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encode_v1,
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encode_v2,
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)
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from omni_pca.opcodes import OmniLink2MessageType, OmniLinkMessageType
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def _ref_crc(data: bytes) -> int:
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"""Independently compute CRC-16/MODBUS using the textbook description."""
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crc = 0
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for b in data:
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crc ^= b
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for _ in range(8):
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crc = (crc >> 1) ^ 0xA001 if crc & 1 else crc >> 1
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return crc & 0xFFFF
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def test_crc_matches_reference_for_empty() -> None:
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assert crc16_modbus(b"") == 0
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def test_crc_pinned_value_for_v1_request_system_info() -> None:
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# length byte = 1 (opcode only), opcode byte = 0x11 (RequestSystemInformation in v1)
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body = bytes([0x01, 0x11])
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expected = _ref_crc(body)
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assert crc16_modbus(body) == expected
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# Pin a concrete number too so future changes need conscious approval.
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assert crc16_modbus(body) == 0x9CC1
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def test_v2_encode_decode_roundtrip() -> None:
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msg = encode_v2(OmniLink2MessageType.RequestSystemInformation)
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wire = msg.encode()
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decoded = Message.decode(wire)
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assert decoded.start_char == START_CHAR_V2
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assert decoded.opcode == OmniLink2MessageType.RequestSystemInformation
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assert decoded.payload == b""
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def test_v2_encode_with_payload() -> None:
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msg = encode_v2(OmniLink2MessageType.Command, payload=bytes([0x01, 0x02, 0x03]))
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wire = msg.encode()
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# [0x21, length=4, opcode=0x14, 0x01, 0x02, 0x03, crc_lo, crc_hi]
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assert wire[0] == 0x21
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assert wire[1] == 4
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assert wire[2] == int(OmniLink2MessageType.Command)
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decoded = Message.decode(wire)
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assert decoded.payload == bytes([0x01, 0x02, 0x03])
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def test_v1_unaddressed_roundtrip() -> None:
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msg = encode_v1(OmniLinkMessageType.RequestSystemInformation)
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wire = msg.encode()
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assert wire[0] == START_CHAR_V1_UNADDRESSED
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decoded = Message.decode(wire)
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assert decoded.start_char == START_CHAR_V1_UNADDRESSED
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assert decoded.opcode == OmniLinkMessageType.RequestSystemInformation
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def test_v1_addressable_roundtrip() -> None:
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msg = encode_v1(OmniLinkMessageType.RequestZoneStatus, serial_address=7)
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wire = msg.encode()
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assert wire[0] == START_CHAR_V1_ADDRESSABLE
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assert wire[1] == 7
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decoded = Message.decode(wire)
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assert decoded.serial_address == 7
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assert decoded.opcode == OmniLinkMessageType.RequestZoneStatus
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def test_crc_tampering_raises() -> None:
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msg = encode_v2(OmniLink2MessageType.RequestSystemInformation)
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wire = bytearray(msg.encode())
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wire[-1] ^= 0xFF
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with pytest.raises(MessageCrcError):
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Message.decode(bytes(wire))
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def test_unknown_start_char_raises() -> None:
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with pytest.raises(MessageFormatError):
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Message.decode(bytes([0xAB, 0x01, 0x02, 0x00, 0x00]))
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def test_truncated_buffer_raises() -> None:
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msg = encode_v2(OmniLink2MessageType.Command, payload=b"\x01\x02\x03")
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wire = msg.encode()
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with pytest.raises(MessageFormatError):
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Message.decode(wire[:-1])
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def test_empty_data_rejected_in_constructor() -> None:
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with pytest.raises(MessageFormatError):
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Message(start_char=START_CHAR_V2, data=b"")
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