anti
41ff6b4b03
First code layer of the OS-fingerprinting work on top of yesterday's vendored p0f v2 database. Three new modules, all pure (no I/O outside of the parser's file read): - decnet/prober/osfp/base.py — Provider protocol + OsMatch dataclass matching the established Provider convention in decnet/geoip and decnet/bus. Docstring spells out the never-raise invariant: malformed input returns None, so a single bad event can't wedge a whole attacker-profile rebuild. - decnet/prober/osfp/p0f/signature.py — Signature dataclass + three predicate helpers (WindowSpec / IntSpec / OptionToken) encoding the p0f v2 DSL's wildcard / modulo / MSS-multiple / MTU-multiple semantics. Scoring is our extension on top of upstream p0f's first-match-wins policy: each signature carries a precomputed specificity in [0, 1] so the factory can pick the most-specific match when multiple signatures fire against one observation. - decnet/prober/osfp/p0f/format.py — .fp line parser. Every shipped field variant from the DSL spec at the top of p0f.fp is covered (Snn / Tnn / %nnn / * for window; T0 vs T; -/@/* os-genre prefixes; quirks as concatenated single-letter flags; '.' sentinels for no-options / no-quirks). Malformed lines log a warning and skip instead of aborting the whole file — 1 bad row must not cost the other 374. 20 parser tests + 14 scoring tests. Full vendored-DB smoke tests confirm all 375 signatures parse round-trip (262 SYN + 61 SYN-ACK + 46 RST + 6 stray) and every computed specificity lands in [0, 1].
126 lines
4.7 KiB
Python
126 lines
4.7 KiB
Python
"""Tests for signature matching + scoring."""
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from __future__ import annotations
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import pytest
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from decnet.prober.osfp.p0f.format import _parse_line
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def _obs(**overrides):
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"""Baseline observation (Linux 2.6 on Ethernet), overridable."""
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base = {
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"window": 5840,
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"ttl": 64,
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"df": True,
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"total_len": 60,
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"options_sig": "M1460,S,T,N,W7",
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"quirks": frozenset(),
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"mss": 1460,
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"wscale": 7,
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}
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base.update(overrides)
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return base
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# ─── Match / no-match ────────────────────────────────────────────────────────
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def test_score_exact_match_is_high() -> None:
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:2.6.x literal")
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score = sig.score(_obs())
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assert score is not None
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assert score >= 0.9, f"literal-fields signature should score high, got {score}"
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def test_score_wildcard_match_is_lower_than_literal() -> None:
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literal = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:literal")
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wildcard = _parse_line("*:64:1:*:M*,S,T,N,W*:.:Linux:wildcard")
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obs = _obs()
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ls = literal.score(obs)
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ws = wildcard.score(obs)
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assert ls is not None and ws is not None
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assert ls > ws, f"literal ({ls}) should outscore wildcard ({ws})"
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def test_score_window_mismatch_returns_none() -> None:
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:fixed")
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assert sig.score(_obs(window=64240)) is None
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def test_score_ttl_mismatch_returns_none() -> None:
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:ttl64")
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assert sig.score(_obs(ttl=128)) is None
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def test_score_df_mismatch_returns_none() -> None:
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:df-required")
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assert sig.score(_obs(df=False)) is None
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def test_score_df_wildcard_on_signature_matches_either() -> None:
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sig = _parse_line("5840:64:*:60:M1460,S,T,N,W7:.:Linux:any-df")
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assert sig.score(_obs(df=True)) is not None
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assert sig.score(_obs(df=False)) is not None
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def test_score_options_order_mismatch_returns_none() -> None:
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:ordered")
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# Same tokens, different order — must NOT match.
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assert sig.score(_obs(options_sig="S,T,M1460,N,W7")) is None
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def test_score_options_missing_token_returns_none() -> None:
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:5opts")
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assert sig.score(_obs(options_sig="M1460,S,T,N")) is None
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def test_score_quirks_must_match_as_set() -> None:
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sig = _parse_line("5840:64:1:60:M*,S,T,N,W*:PZ:Linux:with PZ")
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assert sig.score(_obs(quirks=frozenset({"P", "Z"}))) is not None
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assert sig.score(_obs(quirks=frozenset({"P"}))) is None # missing Z
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assert sig.score(_obs(quirks=frozenset({"P", "Z", "I"}))) is None # extra I
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def test_score_mss_multiple_window() -> None:
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# S4 = 4 * MSS. With MSS=1460 → window=5840.
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sig = _parse_line("S4:64:1:60:M1460,S,T,N,W7:.:Linux:S4")
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assert sig.score(_obs(window=5840, mss=1460)) is not None
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# With MSS=536 → S4 expects window=2144
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assert sig.score(_obs(window=2144, mss=536)) is not None
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assert sig.score(_obs(window=5840, mss=536)) is None
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def test_score_modulo_window() -> None:
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sig = _parse_line("%8192:64:1:60:M1460,S,T,N,W7:.:Linux:mod8192")
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assert sig.score(_obs(window=32768)) is not None
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assert sig.score(_obs(window=40960)) is not None
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assert sig.score(_obs(window=32769)) is None
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def test_score_no_options_sentinel() -> None:
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sig = _parse_line("5840:64:1:60:.:.:Linux:no-opts")
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assert sig.score(_obs(options_sig="")) is not None
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assert sig.score(_obs(options_sig=None)) is not None
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assert sig.score(_obs(options_sig="M1460")) is None
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def test_score_missing_observation_fields_returns_none() -> None:
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"""A signature that requires a specific window can't match when the
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observation has no window. This is the safety invariant —
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sniffer_rollup may call score() with partial data."""
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sig = _parse_line("5840:64:1:60:M1460,S,T,N,W7:.:Linux:strict")
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assert sig.score(_obs(window=None)) is None
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assert sig.score(_obs(ttl=None)) is None
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def test_score_option_value_wildcard_matches_any_literal() -> None:
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sig = _parse_line("5840:64:1:60:M*,S,T,N,W*:.:Linux:wild-mss-wscale")
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assert sig.score(_obs(options_sig="M1460,S,T,N,W7")) is not None
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assert sig.score(_obs(options_sig="M536,S,T,N,W2")) is not None
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def test_score_option_value_modulo() -> None:
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sig = _parse_line("5840:64:1:60:M%4,S,T,N,W7:.:Linux:mss-mod-4")
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assert sig.score(_obs(options_sig="M1460,S,T,N,W7")) is not None # 1460 % 4 == 0
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assert sig.score(_obs(options_sig="M1461,S,T,N,W7")) is None
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