def test_parse_silabs_ebl():
list(validators.parse_silabs_ebl(VALID_EBL_IMAGE))
image = create_ebl_image([(b"AA", b"test"), (b"BB", b"foo" * 20)])
header, tag1, tag2, checksum = validators.parse_silabs_ebl(image)
assert len(image) % 64 == 0
assert header[0] == b"\x00\x00" and len(header[1]) == 140
assert tag1 == (b"AA", b"test")
assert tag2 == (b"BB", b"foo" * 20)
assert checksum[0] == b"\xFC\x04" and len(checksum[1]) == 4
# Padding needs to be a multiple of 64 bytes
with pytest.raises(ValidationError):
list(validators.parse_silabs_ebl(image[:-1]))
with pytest.raises(ValidationError):
list(validators.parse_silabs_ebl(image + b"\xFF"))
# Nothing can come after the padding
assert list(validators.parse_silabs_ebl(image[:-1] + b"\xFF"))
with pytest.raises(ValidationError):
list(validators.parse_silabs_ebl(image[:-1] + b"\xAB"))
# Truncated images are detected
with pytest.raises(ValidationError):
list(
validators.parse_silabs_ebl(image[:image.index(b"test")] +
b"\xFF" * 44))
# As are corrupted images of the correct length but with bad tag lengths
with pytest.raises(ValidationError):
index = image.index(b"test")
bad_image = image[:index - 2] + b"\xFF\xFF" + image[index:]
list(validators.parse_silabs_ebl(bad_image))
# Truncated but at a 64-byte boundary, missing CRC footer
with pytest.raises(ValidationError):
bad_image = create_ebl_image([(b"AA", b"test" * 11)])
bad_image = bad_image[:bad_image.rindex(b"test") + 4]
list(validators.parse_silabs_ebl(bad_image))
# Corrupted images are detected
corrupted_image = image.replace(b"foo", b"goo", 1)
assert image != corrupted_image
with pytest.raises(ValidationError):
list(validators.parse_silabs_ebl(corrupted_image))
def create_ebl_image(tags):
# All images start with a 140-byte "0x0000" header
tags = [(b"\x00\x00", b"jklm" * 35)] + tags
assert all([len(tag) == 2 for tag, value in tags])
image = b"".join(tag + len(value).to_bytes(2, "big") + value
for tag, value in tags)
# And end with a checksum
image += b"\xFC\x04\x00\x04" + zlib.crc32(image +
b"\xFC\x04\x00\x04").to_bytes(
4, "little")
if len(image) % 64 != 0:
image += b"\xFF" * (64 - len(image) % 64)
assert list(validators.parse_silabs_ebl(image))
return image