test(perf): evaluate larger and non-HTTP packet workflows (#3232)

Add reproducible larger/non-HTTP packet cost measurements, an independent header oracle, exact page validation and separate factual/plan grading. Document caller-selected controls and retain negative/mixed model results. Production defaults and APIs remain unchanged.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>
Co-authored-by: Kaoru0822 <208281322+kaoru0822-kitauji@users.noreply.github.com>

experiments/analysis-efficiency/test_packet_oracle.py

@@ -0,0 +1,67 @@
+import importlib.util
+import struct
+import unittest
+from pathlib import Path
+
+spec = importlib.util.spec_from_file_location('packet_oracle', Path(__file__).with_name('packet-oracle.py'))
+oracle = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(oracle)
+
+
+class PacketOracleTest(unittest.TestCase):
+    def test_compression_pointer_preserves_question_cursor(self):
+        message = b'\x03www\x07example\x03com\0' + b'\xc0\0' + b'\0\x01\0\x01'
+        self.assertEqual(oracle.dns_name(message, 17), ('www.example.com', 19))
+
+    def test_compression_cycle_and_missing_pointer_byte_fail(self):
+        for message in (b'\xc0\0', b'\xc0', b'\xc0\x02\xc0\0'):
+            with self.subTest(message=message), self.assertRaises(ValueError):
+                oracle.dns_name(message, 0)
+
+    def test_truncated_pcap_record_is_not_exhaustion(self):
+        header = struct.pack('<IHHIIII', 0xa1b2c3d4, 2, 4, 0, 0, 65535, 1)
+        with self.assertRaises(ValueError):
+            list(oracle.packets(header + b'\0'))
+        record = struct.pack('<IIII', 0, 0, 20, 20)
+        with self.assertRaises(ValueError):
+            list(oracle.packets(header + record + b'\0' * 19))
+
+    def test_missing_dhcp_server_id_stays_omitted(self):
+        payload = b'\0' * 236 + b'\x63\x82\x53\x63\x35\x01\x01\xff'
+        self.assertEqual(oracle.dhcp_options(payload), {53: b'\x01'})
+
+    def test_dhcp_duplicates_truncation_and_missing_end_fail(self):
+        prefix = b'\0' * 236 + b'\x63\x82\x53\x63'
+        for suffix in (b'\x35\x01\x01\x35\x01\x02\xff', b'\x36\x04\0', b'\x35\x01\x01'):
+            with self.subTest(suffix=suffix), self.assertRaises(ValueError):
+                oracle.dhcp_options(prefix + suffix)
+
+    def test_fragmented_selected_traffic_cannot_pass_header_oracle(self):
+        ip = bytearray(20)
+        ip[0], ip[9] = 0x45, 17
+        struct.pack_into('!H', ip, 2, 20)
+        struct.pack_into('!H', ip, 6, 0x2000)
+        with self.assertRaises(ValueError):
+            oracle.transport(b'\0' * 12 + b'\x08\0' + ip)
+
+    def test_declared_ip_length_and_tcp_options_cannot_be_truncated(self):
+        ip = bytearray(40)
+        ip[0], ip[9], ip[32] = 0x45, 6, 0xf0
+        struct.pack_into('!H', ip, 2, 40)
+        struct.pack_into('!HH', ip, 20, 12345, 5432)
+        packet = b'\0' * 12 + b'\x08\0' + ip
+        header = struct.pack('<IHHIIII', 0xa1b2c3d4, 2, 4, 0, 0, 65535, 1)
+        record = struct.pack('<IIII', 0, 0, len(packet), len(packet))
+        with self.assertRaisesRegex(ValueError, 'TCP header'):
+            oracle.analyze(header + record + packet, 'postgres')
+        struct.pack_into('!H', ip, 2, 60)
+        with self.assertRaisesRegex(ValueError, 'truncated IPv4'):
+            oracle.transport(b'\0' * 12 + b'\x08\0' + ip)
+
+    def test_unknown_link_protocol_does_not_prove_tcp_absence(self):
+        with self.assertRaisesRegex(ValueError, 'unsupported Ethernet'):
+            oracle.transport(b'\0' * 12 + b'\x86\xdd' + b'\0' * 40)
+
+
+if __name__ == '__main__':
+    unittest.main()