|
| 1 | +# -*- coding: utf-8 -*- |
| 2 | +"""GitHub issue #2362: a made PCAP-NG block defaults its timestamp to the clock. |
| 3 | +
|
| 4 | +Without the fix, :meth:`PCAPNG._make_timestamp |
| 5 | +<pcapkit.protocols.misc.pcapng.PCAPNG._make_timestamp>` picks the clock a |
| 6 | +defaulted timestamp is read to by reading :attr:`PCAPNG.nanosecond |
| 7 | +<pcapkit.protocols.misc.pcapng.PCAPNG.nanosecond>`, which resolves its |
| 8 | +interface through the parsed data model a block being made has not got, so |
| 9 | +``make()`` without a ``timestamp`` raises |
| 10 | +``AttributeError: 'PCAPNG' object has no attribute '_info'`` for every block |
| 11 | +carrying one -- the Enhanced Packet Block, the obsolete Packet Block and the |
| 12 | +Interface Statistics Block, the last through its ``isb_starttime`` and |
| 13 | +``isb_endtime`` options as well as its own field. The resolution comes from the |
| 14 | +interface ID the maker is given, so a defaulted timestamp is the current time, |
| 15 | +read from the clock that interface's declared resolution calls for and scaled |
| 16 | +to its units. |
| 17 | +
|
| 18 | +Every case builds its own blocks in memory and reads no capture. |
| 19 | +
|
| 20 | +:mod:`pcapkit` is imported inside each test, after |
| 21 | +:func:`~tests._support.reimport_once_per_class`. |
| 22 | +
|
| 23 | +""" |
| 24 | + |
| 25 | +import time |
| 26 | +import unittest |
| 27 | +import unittest.mock |
| 28 | +import warnings |
| 29 | +from typing import TYPE_CHECKING |
| 30 | + |
| 31 | +from tests.protocols.misc.test_pcapng_roundtrip2_unit import PCAPNGTestCase |
| 32 | + |
| 33 | +if TYPE_CHECKING: |
| 34 | + from typing import Any, Optional |
| 35 | + |
| 36 | +#: Blocks whose maker defaults a timestamp, named rather than imported so that |
| 37 | +#: this module loads without :mod:`pcapkit`. |
| 38 | +TIMESTAMPED = ('Enhanced_Packet_Block', 'Packet_Block', 'Interface_Statistics_Block') |
| 39 | + |
| 40 | +#: ``if_tsresol``'s own default, in units per second: a block whose interface |
| 41 | +#: declares none counts microseconds. |
| 42 | +DEFAULT_RESOLUTION = 1_000_000 |
| 43 | + |
| 44 | +#: ``if_tsresol`` of 9, in units per second: the resolution a block has to |
| 45 | +#: declare for its default to be read from :func:`time.time_ns`. |
| 46 | +NANOSECOND_RESOLUTION = 1_000_000_000 |
| 47 | + |
| 48 | +#: A :func:`time.time_ns` reading to pin, far enough from both the current time |
| 49 | +#: and :data:`PINNED_SECOND` that the field it reaches names the clock it came |
| 50 | +#: from. |
| 51 | +PINNED_NANOSECOND = 1_700_000_000_123_456_789 |
| 52 | + |
| 53 | +#: A :func:`time.time` reading to pin, exactly representable so that scaling it |
| 54 | +#: to :data:`DEFAULT_RESOLUTION` is exact. |
| 55 | +PINNED_SECOND = 1_600_000_000.5 |
| 56 | + |
| 57 | +#: The raw timestamp field a defaulted timestamp is written to at each |
| 58 | +#: resolution, with both clocks pinned and no ``if_tsoffset`` in play. The |
| 59 | +#: nanosecond entry is :data:`PINNED_NANOSECOND` written in its own units; the |
| 60 | +#: microsecond one is :data:`PINNED_SECOND` scaled, which is a value the |
| 61 | +#: nanosecond clock cannot produce and vice versa. |
| 62 | +PINNED_RAW = { |
| 63 | + NANOSECOND_RESOLUTION: PINNED_NANOSECOND, |
| 64 | + DEFAULT_RESOLUTION: int(PINNED_SECOND * DEFAULT_RESOLUTION), |
| 65 | +} |
| 66 | + |
| 67 | + |
| 68 | +class TestPCAPNGDefaultTimestamp(PCAPNGTestCase): |
| 69 | + """Pin the timestamp a block is made with when the caller names none.""" |
| 70 | + |
| 71 | + def _timed_context(self, resolution: 'Optional[int]' = None, |
| 72 | + offset: 'Optional[int]' = None) -> 'Any': |
| 73 | + """A one-interface context, optionally with ``if_tsresol``/``if_tsoffset``. |
| 74 | +
|
| 75 | + Its own, rather than :meth:`PCAPNGTestCase._context |
| 76 | + <tests.protocols.misc.test_pcapng_roundtrip2_unit.PCAPNGTestCase._context>`, |
| 77 | + because the interface needs options the base helper does not take. |
| 78 | +
|
| 79 | + """ |
| 80 | + from pcapkit.const.pcapng.block_type import BlockType |
| 81 | + from pcapkit.foundation.engines.pcapng import Context |
| 82 | + from pcapkit.protocols.misc.pcapng import PCAPNG |
| 83 | + |
| 84 | + section = PCAPNG(num=0, sct=1, ctx=None, type=BlockType.Section_Header_Block, block={}) |
| 85 | + context = Context(section.info) # type: Any |
| 86 | + self._add_interface(context, resolution=resolution, offset=offset) |
| 87 | + return context |
| 88 | + |
| 89 | + def _add_interface(self, context: 'Any', resolution: 'Optional[int]' = None, |
| 90 | + offset: 'Optional[int]' = None) -> 'Any': |
| 91 | + """Append one Ethernet interface to ``context``, and return its data model. |
| 92 | +
|
| 93 | + Its index in the section is the ``interface_id`` a block names to be |
| 94 | + read at this interface's ``if_tsresol`` and ``if_tsoffset``. |
| 95 | +
|
| 96 | + """ |
| 97 | + from pcapkit.const.pcapng.block_type import BlockType |
| 98 | + from pcapkit.const.pcapng.option_type import OptionType |
| 99 | + from pcapkit.const.reg.linktype import LinkType |
| 100 | + from pcapkit.protocols.misc.pcapng import PCAPNG |
| 101 | + |
| 102 | + options = [] # type: list[Any] |
| 103 | + if resolution is not None: |
| 104 | + options.append((OptionType.if_tsresol, {'resolution': resolution})) |
| 105 | + if offset is not None: |
| 106 | + options.append((OptionType.if_tsoffset, {'offset': offset})) |
| 107 | + |
| 108 | + interface = PCAPNG(num=len(context.interfaces) + 1, sct=1, ctx=context, |
| 109 | + type=BlockType.Interface_Description_Block, |
| 110 | + block={'linktype': LinkType.ETHERNET, 'snaplen': 0, |
| 111 | + 'options': options}) |
| 112 | + context.interfaces.append(interface.info) |
| 113 | + return interface.info |
| 114 | + |
| 115 | + def assertIsNow(self, epoch: 'Any', before: 'float', after: 'float', # pylint: disable=invalid-name |
| 116 | + resolution: 'int' = DEFAULT_RESOLUTION) -> 'None': |
| 117 | + """Assert ``epoch`` is a clock read taken between ``before`` and ``after``. |
| 118 | +
|
| 119 | + The field holds an integer count of ``resolution`` units, so the epoch |
| 120 | + it reads back as can sit up to one unit below ``before``, which is a |
| 121 | + full-precision :func:`time.time`. |
| 122 | +
|
| 123 | + """ |
| 124 | + self.assertGreaterEqual(float(epoch), before - 1 / resolution) |
| 125 | + self.assertLessEqual(float(epoch), after) |
| 126 | + |
| 127 | + def _raw_timestamp(self, made: 'Any') -> 'int': |
| 128 | + """The raw Timestamp (High)/(Low) pair of ``made``, in its own units.""" |
| 129 | + block = made.schema.block |
| 130 | + return (block.timestamp_high << 32) | block.timestamp_low |
| 131 | + |
| 132 | + def _make(self, name: 'str', context: 'Any', **block: 'Any') -> 'Any': |
| 133 | + """Make the block named ``name`` over ``context``, with no ``timestamp``.""" |
| 134 | + from pcapkit.const.pcapng.block_type import BlockType |
| 135 | + from pcapkit.protocols.misc.pcapng import PCAPNG |
| 136 | + |
| 137 | + with warnings.catch_warnings(): |
| 138 | + warnings.simplefilter('ignore') # the Packet Block is obsolete |
| 139 | + return PCAPNG(num=2, sct=1, ctx=context, type=BlockType.get(name), block=block) |
| 140 | + |
| 141 | + def test_default_is_the_current_time(self) -> None: |
| 142 | + """The issue's case: no ``timestamp`` makes one, and it is now.""" |
| 143 | + context = self._timed_context() |
| 144 | + for name in TIMESTAMPED: |
| 145 | + with self.subTest(block=name): |
| 146 | + before = time.time() |
| 147 | + made = self._make(name, context, packet_data=b'A' * 4) |
| 148 | + after = time.time() |
| 149 | + self.assertIsNow(made.info.timestamp_epoch, before, after) |
| 150 | + |
| 151 | + def test_default_survives_a_round_trip(self) -> None: |
| 152 | + """A defaulted timestamp parses back to the value the maker reported.""" |
| 153 | + from pcapkit.protocols.misc.pcapng import PCAPNG |
| 154 | + |
| 155 | + context = self._timed_context() |
| 156 | + for name in TIMESTAMPED: |
| 157 | + with self.subTest(block=name): |
| 158 | + made = self._make(name, context, packet_data=b'A' * 4) |
| 159 | + with warnings.catch_warnings(): |
| 160 | + warnings.simplefilter('ignore') # the Packet Block is obsolete |
| 161 | + parsed = PCAPNG(made.data, len(made.data), num=2, sct=1, ctx=context) |
| 162 | + self.assertEqual(parsed.info.timestamp_epoch, made.info.timestamp_epoch) |
| 163 | + self.assertRebuilds(made.data, context) |
| 164 | + |
| 165 | + def test_default_is_read_at_the_interface_resolution(self) -> None: |
| 166 | + """``if_tsresol`` of 9 scales the default to nanoseconds, not microseconds.""" |
| 167 | + context = self._timed_context(resolution=NANOSECOND_RESOLUTION) |
| 168 | + for name in TIMESTAMPED: |
| 169 | + with self.subTest(block=name): |
| 170 | + before = time.time_ns() |
| 171 | + made = self._make(name, context, packet_data=b'A' * 4) |
| 172 | + after = time.time_ns() |
| 173 | + # The raw field counts nanoseconds, so it is of the order of |
| 174 | + # ``time.time_ns()``; read at microseconds it would be a |
| 175 | + # thousandth of that and fall below ``before``. |
| 176 | + raw = self._raw_timestamp(made) |
| 177 | + self.assertGreaterEqual(raw, before) |
| 178 | + self.assertLessEqual(raw, after) |
| 179 | + |
| 180 | + def _make_on_pinned_clocks(self, name: 'str', context: 'Any', **block: 'Any') -> 'Any': |
| 181 | + """Make the block named ``name`` with both clocks pinned. |
| 182 | +
|
| 183 | + :func:`time.time_ns` reads :data:`PINNED_NANOSECOND` and |
| 184 | + :func:`time.time` reads :data:`PINNED_SECOND`, so the field a default |
| 185 | + reaches names the clock it was read from. Left to the real clocks the |
| 186 | + two are each about the current time, and the field cannot tell them |
| 187 | + apart. |
| 188 | +
|
| 189 | + """ |
| 190 | + with unittest.mock.patch('time.time_ns', return_value=PINNED_NANOSECOND), \ |
| 191 | + unittest.mock.patch('time.time', return_value=PINNED_SECOND): |
| 192 | + return self._make(name, context, **block) |
| 193 | + |
| 194 | + def test_default_follows_the_interface_the_block_names(self) -> None: |
| 195 | + """A block reads its own ``interface_id``'s resolution, not interface 0's. |
| 196 | +
|
| 197 | + The section carries two interfaces a thousandfold apart and every block |
| 198 | + names the second one, in both orders, with the clocks pinned: a lookup |
| 199 | + fixed at interface 0 therefore reads the wrong clock and scales by the |
| 200 | + wrong factor, whichever way round the section is written. |
| 201 | +
|
| 202 | + """ |
| 203 | + for first, second in ((None, NANOSECOND_RESOLUTION), |
| 204 | + (NANOSECOND_RESOLUTION, None)): |
| 205 | + resolution = second or DEFAULT_RESOLUTION |
| 206 | + context = self._timed_context(resolution=first) |
| 207 | + self._add_interface(context, resolution=second) |
| 208 | + for name in TIMESTAMPED: |
| 209 | + with self.subTest(block=name, resolution=resolution): |
| 210 | + made = self._make_on_pinned_clocks(name, context, interface_id=1, |
| 211 | + packet_data=b'A' * 4) |
| 212 | + self.assertEqual(made.info.interface_id, 1) |
| 213 | + self.assertEqual(self._raw_timestamp(made), PINNED_RAW[resolution]) |
| 214 | + |
| 215 | + def test_default_reads_the_clock_its_resolution_calls_for(self) -> None: |
| 216 | + """A sub-microsecond resolution reads :func:`time.time_ns`, a coarser one :func:`time.time`. |
| 217 | +
|
| 218 | + ``None`` is an interface that declares no ``if_tsresol`` at all, which |
| 219 | + counts :data:`DEFAULT_RESOLUTION` units and so reads the coarse clock. |
| 220 | +
|
| 221 | + """ |
| 222 | + for declared in (NANOSECOND_RESOLUTION, None): |
| 223 | + resolution = declared or DEFAULT_RESOLUTION |
| 224 | + context = self._timed_context(resolution=declared) |
| 225 | + for name in TIMESTAMPED: |
| 226 | + with self.subTest(block=name, resolution=resolution): |
| 227 | + made = self._make_on_pinned_clocks(name, context, packet_data=b'A' * 4) |
| 228 | + self.assertEqual(self._raw_timestamp(made), PINNED_RAW[resolution]) |
| 229 | + |
| 230 | + def test_default_is_shifted_by_the_interface_offset(self) -> None: |
| 231 | + """``if_tsoffset`` shifts the written field, not the epoch reported.""" |
| 232 | + context = self._timed_context(offset=1_000) |
| 233 | + for name in TIMESTAMPED: |
| 234 | + with self.subTest(block=name): |
| 235 | + before = time.time() |
| 236 | + made = self._make(name, context, packet_data=b'A' * 4) |
| 237 | + after = time.time() |
| 238 | + self.assertIsNow(made.info.timestamp_epoch, before, after) |
| 239 | + raw = self._raw_timestamp(made) |
| 240 | + self.assertAlmostEqual(raw / 1_000_000 + 1_000, before, delta=1) |
| 241 | + |
| 242 | + def test_isb_start_and_end_times_default_too(self) -> None: |
| 243 | + """``isb_starttime``/``isb_endtime`` reach the same maker, so they default too.""" |
| 244 | + from pcapkit.const.pcapng.option_type import OptionType |
| 245 | + |
| 246 | + context = self._timed_context() |
| 247 | + before = time.time() |
| 248 | + made = self._make('Interface_Statistics_Block', context, |
| 249 | + options=[(OptionType.isb_starttime, {}), |
| 250 | + (OptionType.isb_endtime, {})]) |
| 251 | + after = time.time() |
| 252 | + for option in (OptionType.isb_starttime, OptionType.isb_endtime): |
| 253 | + with self.subTest(option=option): |
| 254 | + self.assertIsNow(made.info.options[option].timestamp_epoch, before, after) |
| 255 | + |
| 256 | + def test_an_explicit_timestamp_is_unchanged(self) -> None: |
| 257 | + """The fix touches only the default: an explicit ``timestamp`` still writes 0.""" |
| 258 | + context = self._timed_context() |
| 259 | + for name in TIMESTAMPED: |
| 260 | + with self.subTest(block=name): |
| 261 | + made = self._make(name, context, packet_data=b'A' * 4, timestamp=0) |
| 262 | + self.assertEqual(made.info.timestamp_epoch, 0) |
| 263 | + |
| 264 | + |
| 265 | +if __name__ == '__main__': |
| 266 | + unittest.main() |
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