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.
102 lines
2.9 KiB
Python
102 lines
2.9 KiB
Python
"""Unit tests for omni_pca.pca_file.
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The full ``.pca`` parser is exercised via the live fixture in pca-re/extracted
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which is not committed; here we validate the LCG keystream + reader plumbing
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on synthesized inputs and skip the full-body test by default.
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"""
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from __future__ import annotations
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import io
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import struct
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import pytest
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from omni_pca.pca_file import (
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KEY_EXPORT,
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KEY_PC01,
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PcaReader,
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decrypt_pca_bytes,
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derive_key_from_stamp,
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)
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def _encrypt_with_lcg(plain: bytes, key: int) -> bytes:
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"""Reference encryptor (mirrors decrypt_pca_bytes — same op since XOR)."""
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return decrypt_pca_bytes(plain, key)
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def test_decrypt_is_xor_involution() -> None:
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plain = b"CFG05 hello world payload"
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ct = _encrypt_with_lcg(plain, 0xDEADBEEF)
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assert decrypt_pca_bytes(ct, 0xDEADBEEF) == plain
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def test_keystream_never_emits_0xff() -> None:
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# The Borland LCG's `% 255` quirk means keystream values are in [0..254].
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# Encrypting a buffer of 0xFF bytes should never produce 0x00.
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ct = _encrypt_with_lcg(b"\xff" * 4096, 0x12345678)
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assert all(b != 0x00 for b in ct)
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def test_keys_are_distinct() -> None:
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assert KEY_PC01 != KEY_EXPORT
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def test_keys_match_decompiled_constants() -> None:
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# Pin to the literal uint values from clsPcaCfg.cs (decompiled C#).
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# Hex form of each is right next to the constant in pca_file.py.
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assert KEY_PC01 == 338847091
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assert KEY_EXPORT == 391549495
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def test_derive_key_from_stamp_is_deterministic() -> None:
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a = derive_key_from_stamp("hello")
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b = derive_key_from_stamp("hello")
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assert a == b
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assert a != derive_key_from_stamp("hellp")
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def test_pca_reader_basic_types() -> None:
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buf = bytes([0x05]) + struct.pack("<H", 0xBEEF) + struct.pack("<I", 0xDEADBEEF)
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r = PcaReader(buf)
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assert r.u8() == 0x05
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assert r.u16() == 0xBEEF
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assert r.u32() == 0xDEADBEEF
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def test_pca_reader_string8_fixed_consumes_full_slot() -> None:
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# declared len=3, max_len=10 → consumes 1 + 10 bytes regardless
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payload = bytes([3]) + b"abc" + b"\x00" * 7
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r = PcaReader(payload + b"TAIL")
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s = r.string8_fixed(10)
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assert s == "abc"
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assert r.remaining() == b"TAIL"
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def test_pca_reader_string16_fixed_consumes_full_slot() -> None:
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payload = struct.pack("<H", 2) + b"ok" + b"\x00" * 4 + b"TAIL"
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r = PcaReader(payload)
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s = r.string16_fixed(6)
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assert s == "ok"
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assert r.remaining() == b"TAIL"
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def test_pca_reader_short_read_raises() -> None:
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r = PcaReader(b"\x00\x00")
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with pytest.raises(EOFError):
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r.u32()
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@pytest.mark.skip(reason="needs the gitignored extracted/Our_House.pca fixture")
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def test_full_pca_parse_against_real_fixture() -> None:
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# Placeholder — wire up if/when a redacted fixture lands in tests/fixtures/.
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pass
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def test_pca_reader_io_state_introspection() -> None:
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r = PcaReader(b"abcdef")
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assert isinstance(r.buf, io.BytesIO)
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r.bytes_(2)
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assert r.position() == 2
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