feat(pr2): HTTP/2+HTTP/3 fingerprint extractors — JA4H, H2 SETTINGS, JA4-QUIC

tests/sniffer/test_quic_initial.py

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+"""Tests for QUIC v1 Initial packet key derivation (RFC 9001 Appendix A vectors)."""
+from __future__ import annotations
+
+import pytest
+
+from decnet.sniffer.fingerprint import (
+    _hkdf_extract,
+    _hkdf_expand_label,
+    _quic_initial_keys,
+    _QUIC_V1_INITIAL_SALT,
+    _ja4_quic,
+    _parse_quic_initial,
+)
+
+
+# RFC 9001 Appendix A.1 key derivation test vectors
+_RFC9001_DCID = bytes.fromhex("8394c8f03e515708")
+_RFC9001_CLIENT_KEY = bytes.fromhex("1f369613dd76d5467730efcbe3b1a22d")
+_RFC9001_CLIENT_IV = bytes.fromhex("fa044b2f42a3fd3b46fb255c")
+_RFC9001_CLIENT_HP = bytes.fromhex("9f50449e04a0e810283a1e9933adedd2")
+
+
+class TestHKDF:
+    def test_extract_sha256(self):
+        # HKDF-Extract is HMAC-SHA256(salt, IKM). Cross-check with a known value.
+        result = _hkdf_extract(b"salt", b"ikm")
+        import hmac, hashlib
+        expected = hmac.new(b"salt", b"ikm", hashlib.sha256).digest()
+        assert result == expected
+
+    def test_expand_label_length(self):
+        secret = _hkdf_extract(_QUIC_V1_INITIAL_SALT, _RFC9001_DCID)
+        # "client in" expand should be 32 bytes
+        client_secret = _hkdf_expand_label(secret, "client in", b"", 32)
+        assert len(client_secret) == 32
+
+    def test_expand_label_key_length(self):
+        secret = _hkdf_extract(_QUIC_V1_INITIAL_SALT, _RFC9001_DCID)
+        client_secret = _hkdf_expand_label(secret, "client in", b"", 32)
+        key = _hkdf_expand_label(client_secret, "quic key", b"", 16)
+        assert len(key) == 16
+
+    def test_expand_label_iv_length(self):
+        secret = _hkdf_extract(_QUIC_V1_INITIAL_SALT, _RFC9001_DCID)
+        client_secret = _hkdf_expand_label(secret, "client in", b"", 32)
+        iv = _hkdf_expand_label(client_secret, "quic iv", b"", 12)
+        assert len(iv) == 12
+
+
+class TestQuicInitialKeys:
+    def test_rfc9001_appendix_a_vectors(self):
+        """Key derivation must match RFC 9001 Appendix A.1 test vectors exactly."""
+        key, iv, hp = _quic_initial_keys(_RFC9001_DCID)
+        assert key == _RFC9001_CLIENT_KEY, f"key mismatch: {key.hex()}"
+        assert iv == _RFC9001_CLIENT_IV, f"iv mismatch: {iv.hex()}"
+        assert hp == _RFC9001_CLIENT_HP, f"hp mismatch: {hp.hex()}"
+
+
+class TestJA4Quic:
+    def test_proto_prefix_is_q(self):
+        ch = {
+            "cipher_suites": [0x1301, 0x1302],
+            "extensions": [0x000a, 0x000d, 0x002b],
+            "signature_algorithms": [0x0403, 0x0804],
+            "supported_versions": [0x0304],
+            "sni": "example.com",
+            "alpn": ["h3"],
+            "tls_version": 0x0303,
+        }
+        result = _ja4_quic(ch)
+        assert result.startswith("q"), f"expected 'q' prefix: {result}"
+
+    def test_structure(self):
+        ch = {
+            "cipher_suites": [0x1301],
+            "extensions": [0x000a],
+            "signature_algorithms": [],
+            "supported_versions": [0x0304],
+            "sni": "",
+            "alpn": [],
+            "tls_version": 0x0303,
+        }
+        result = _ja4_quic(ch)
+        parts = result.split("_")
+        assert len(parts) == 3
+
+    def test_deterministic(self):
+        ch = {
+            "cipher_suites": [0x1301, 0x1302, 0x1303],
+            "extensions": [0x000a, 0x000d],
+            "signature_algorithms": [0x0403],
+            "supported_versions": [0x0304],
+            "sni": "host.example",
+            "alpn": ["h3"],
+            "tls_version": 0x0303,
+        }
+        assert _ja4_quic(ch) == _ja4_quic(ch)
+
+
+class TestParseQuicInitial:
+    def test_short_header_rejected(self):
+        # Short header: bit 7 clear
+        assert _parse_quic_initial(b"\x40" + b"\x00" * 20) is None
+
+    def test_wrong_version_rejected(self):
+        # Long header, Initial type, version = 0x00000002
+        pkt = bytearray(30)
+        pkt[0] = 0xC0  # long header + Initial
+        pkt[1:5] = b"\x00\x00\x00\x02"  # version 2
+        assert _parse_quic_initial(bytes(pkt)) is None
+
+    def test_non_initial_type_rejected(self):
+        # Long header, Handshake type (0x20 set)
+        pkt = bytearray(30)
+        pkt[0] = 0xE0  # long header + Handshake
+        pkt[1:5] = b"\x00\x00\x00\x01"
+        assert _parse_quic_initial(bytes(pkt)) is None
+
+    def test_garbage_returns_none(self):
+        assert _parse_quic_initial(b"garbage bytes that are not QUIC") is None
+
+    def test_too_short_returns_none(self):
+        assert _parse_quic_initial(b"\xc0\x00") is None