import logging
import traceback
from django.utils import timezone
from ESSArch_Core.essxml.util import find_file
from ESSArch_Core.exceptions import ValidationError
from ESSArch_Core.fixity.checksum import calculate_checksum
from ESSArch_Core.fixity.models import Validation
from ESSArch_Core.fixity.validation.backends.base import BaseValidator
logger = logging.getLogger('essarch.fixity.validation.checksum')
[docs]
class ChecksumValidator(BaseValidator):
"""
Validates the checksum of a file against the given ``context``.
* ``context`` specifies how the input is given and must be one of
``checksum_file``, ``checksum_str`` and ``xml_file``
* ``options``
* ``algorithm`` must be one of ``md5``, ``sha-1``, ``sha-224``,
``sha-256``, ``sha-384`` and ``sha-512``. Defaults to ``md5``
* ``block_size``: Defaults to 65536
"""
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
if not self.context:
raise ValueError('Need something to compare to')
self.algorithm = self.options.get('algorithm', 'md5')
self.block_size = self.options.get('block_size', 65536)
def validate(self, filepath, expected=None):
logger.debug('Validating checksum of %s' % filepath)
val_obj = Validation.objects.create(
filename=filepath,
time_started=timezone.now(),
validator=self.__class__.__name__,
required=self.required,
task=self.task,
information_package=self.ip,
responsible=self.responsible,
specification={
'context': self.context,
'options': self.options,
}
)
expected = self.options['expected'].format(**self.data)
if self.context == 'checksum_str':
checksum = expected.lower()
elif self.context == 'checksum_file':
with open(expected, 'r') as checksum_file:
checksum = checksum_file.read().strip()
elif self.context == 'xml_file':
xml_el, _ = find_file(filepath, xmlfile=expected)
checksum = xml_el.checksum
passed = False
try:
actual_checksum = calculate_checksum(filepath, algorithm=self.algorithm, block_size=self.block_size)
if actual_checksum != checksum:
raise ValidationError("checksum for %s is not valid (%s != %s)" % (
filepath, checksum, actual_checksum
))
passed = True
except Exception:
val_obj.message = traceback.format_exc()
raise
else:
message = 'Successfully validated checksum of %s' % filepath
val_obj.message = message
logger.info(message)
finally:
val_obj.time_done = timezone.now()
val_obj.passed = passed
val_obj.save(update_fields=['time_done', 'passed', 'message'])