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# Copyright 2018 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import functools
import itertools
from unittest import mock
import pytest # type: ignore
import google_crc32c
EMPTY = b""
EMPTY_CRC = 0x00000000
# From: https://tools.ietf.org/html/rfc3720#appendix-B.4
#
# 32 bytes of zeroes:
#
# Byte: 0 1 2 3
#
# 0: 00 00 00 00
# ...
# 28: 00 00 00 00
#
# CRC: aa 36 91 8a
ALL_ZEROS = b"\x00" * 32
ALL_ZEROS_CRC = 0x8A9136AA
# 32 bytes of ones:
#
# Byte: 0 1 2 3
#
# 0: ff ff ff ff
# ...
# 28: ff ff ff ff
#
# CRC: 43 ab a8 62
ALL_ONES = b"\xff" * 32
ALL_ONES_CRC = 0x62A8AB43
#
# 32 bytes of incrementing 00..1f:
#
# Byte: 0 1 2 3
#
# 0: 00 01 02 03
# ...
# 28: 1c 1d 1e 1f
#
# CRC: 4e 79 dd 46
INCREMENTING = bytes(range(32))
INCREMENTING_CRC = 0x46DD794E
#
# 32 bytes of decrementing 1f..00:
#
# Byte: 0 1 2 3
#
# 0: 1f 1e 1d 1c
# ...
# 28: 03 02 01 00
#
# CRC: 5c db 3f 11
DECREMENTING = bytes(reversed(range(32)))
DECREMENTING_CRC = 0x113FDB5C
#
# An iSCSI - SCSI Read (10) Command PDU
#
# Byte: 0 1 2 3
#
# 0: 01 c0 00 00
# 4: 00 00 00 00
# 8: 00 00 00 00
# 12: 00 00 00 00
# 16: 14 00 00 00
# 20: 00 00 04 00
# 24: 00 00 00 14
# 28: 00 00 00 18
# 32: 28 00 00 00
# 36: 00 00 00 00
# 40: 02 00 00 00
# 44: 00 00 00 00
#
# CRC: 56 3a 96 d9
ISCSI_SCSI_READ_10_COMMAND_PDU = [
0x01,
0xC0,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x14,
0x00,
0x00,
0x00,
0x00,
0x00,
0x04,
0x00,
0x00,
0x00,
0x00,
0x14,
0x00,
0x00,
0x00,
0x18,
0x28,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x02,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
]
ISCSI_LENGTH = len(ISCSI_SCSI_READ_10_COMMAND_PDU)
ISCSI_BYTES = bytes(ISCSI_SCSI_READ_10_COMMAND_PDU)
ISCSI_CRC = 0xD9963A56
def iscsi_chunks(chunksize):
for index in itertools.islice(range(ISCSI_LENGTH), 0, None, chunksize):
yield ISCSI_SCSI_READ_10_COMMAND_PDU[index : index + chunksize]
_EXPECTED = [
(EMPTY, EMPTY_CRC),
(ALL_ZEROS, ALL_ZEROS_CRC),
(ALL_ONES, ALL_ONES_CRC),
(INCREMENTING, INCREMENTING_CRC),
(DECREMENTING, DECREMENTING_CRC),
(ISCSI_SCSI_READ_10_COMMAND_PDU, ISCSI_CRC),
(ISCSI_BYTES, ISCSI_CRC),
]
def test_extend_w_empty_chunk():
crc = 123
assert google_crc32c.extend(crc, b"") == crc
def test_extend_w_multiple_chunks():
crc = 0
for chunk in iscsi_chunks(7):
chunk_bytes = bytes(chunk)
crc = google_crc32c.extend(crc, chunk_bytes)
assert crc == ISCSI_CRC
def test_extend_w_reduce():
chunks = [bytes(chunk) for chunk in iscsi_chunks(3)]
assert functools.reduce(google_crc32c.extend, chunks, 0) == ISCSI_CRC
@pytest.mark.parametrize("chunk, expected", _EXPECTED)
def test_value(chunk, expected):
assert google_crc32c.value(bytes(chunk)) == expected
def pytest_generate_tests(metafunc):
if "_crc32c" in metafunc.fixturenames:
metafunc.parametrize("_crc32c", ["python", "cext"], indirect=True)
@pytest.fixture
def _crc32c(request):
if request.param == "python":
from google_crc32c import python
return python
elif request.param == "cext":
from google_crc32c import cext
return cext
else:
raise ValueError("invalid internal test config")
class TestChecksum(object):
@staticmethod
def test_ctor_defaults(_crc32c):
helper = google_crc32c.Checksum()
assert helper._crc == 0
@staticmethod
def test_ctor_explicit(_crc32c):
chunk = b"DEADBEEF"
helper = google_crc32c.Checksum(chunk)
assert helper._crc == google_crc32c.value(chunk)
@staticmethod
def test_update(_crc32c):
chunk = b"DEADBEEF"
helper = google_crc32c.Checksum()
helper.update(chunk)
assert helper._crc == google_crc32c.value(chunk)
@staticmethod
def test_update_w_multiple_chunks(_crc32c):
helper = google_crc32c.Checksum()
for index in itertools.islice(range(ISCSI_LENGTH), 0, None, 7):
chunk = ISCSI_SCSI_READ_10_COMMAND_PDU[index : index + 7]
helper.update(bytes(chunk))
assert helper._crc == ISCSI_CRC
@staticmethod
def test_digest_zero(_crc32c):
helper = google_crc32c.Checksum()
assert helper.digest() == b"\x00" * 4
@staticmethod
def test_digest_nonzero(_crc32c):
helper = google_crc32c.Checksum()
helper._crc = 0x01020304
assert helper.digest() == b"\x01\x02\x03\x04"
@staticmethod
def test_hexdigest_zero(_crc32c):
helper = google_crc32c.Checksum()
assert helper.hexdigest() == b"00" * 4
@staticmethod
def test_hexdigest_nonzero(_crc32c):
helper = google_crc32c.Checksum()
helper._crc = 0x091A3B2C
assert helper.hexdigest() == b"091a3b2c"
@staticmethod
def test_copy(_crc32c):
chunk = b"DEADBEEF"
helper = google_crc32c.Checksum(chunk)
clone = helper.copy()
before = helper._crc
helper.update(b"FACEDACE")
assert clone._crc == before
@staticmethod
@pytest.mark.parametrize("chunksize", [1, 3, 5, 7, 11, 13, ISCSI_LENGTH])
def test_consume_stream(_crc32c, chunksize):
helper = google_crc32c.Checksum()
expected = [bytes(chunk) for chunk in iscsi_chunks(chunksize)]
stream = mock.Mock(spec=["read"])
stream.read.side_effect = expected + [b""]
found = list(helper.consume(stream, chunksize))
assert helper._crc == ISCSI_CRC
assert found == expected
for call in stream.read.call_args_list:
assert call == mock.call(chunksize)
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