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django-q2/django_q/core_signing.py
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Ilan Steemers 15155c7a99 Build improvements (#569)
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2021-05-30 17:10:07 +02:00

81 lines
2.6 KiB
Python

import datetime
import time
import zlib
from django.core.signing import BadSignature, JSONSerializer, SignatureExpired
from django.core.signing import Signer as Sgnr
from django.core.signing import TimestampSigner as TsS
from django.core.signing import b64_decode, dumps
from django.utils import baseconv
from django.utils.crypto import constant_time_compare
from django.utils.encoding import force_bytes, force_str
dumps = dumps
"""
The loads function is the same as the `django.core.signing.loads` function
The difference is that `this` loads function calls `TimestampSigner` and `Signer`
"""
def loads(
s,
key=None,
salt: str = "django.core.signing",
serializer=JSONSerializer,
max_age=None,
):
"""
Reverse of dumps(), raise BadSignature if signature fails.
The serializer is expected to accept a bytestring.
"""
# TimestampSigner.unsign() returns str but base64 and zlib compression
# operate on bytes.
base64d = force_bytes(TimestampSigner(key, salt=salt).unsign(s, max_age=max_age))
decompress = False
if base64d[:1] == b".":
# It's compressed; uncompress it first
base64d = base64d[1:]
decompress = True
data = b64_decode(base64d)
if decompress:
data = zlib.decompress(data)
return serializer().loads(data)
class Signer(Sgnr):
def unsign(self, signed_value):
signed_value = force_str(signed_value)
if self.sep not in signed_value:
raise BadSignature('No "%s" found in value' % self.sep)
value, sig = signed_value.rsplit(self.sep, 1)
if constant_time_compare(sig, self.signature(value)):
return force_str(value)
raise BadSignature('Signature "%s" does not match' % sig)
"""
TimestampSigner is also the same as `django.core.signing.TimestampSigner` but is
calling `this` Signer.
"""
class TimestampSigner(Signer, TsS):
def unsign(self, value, max_age=None):
"""
Retrieve original value and check it wasn't signed more
than max_age seconds ago.
"""
result = super(TimestampSigner, self).unsign(value)
value, timestamp = result.rsplit(self.sep, 1)
timestamp = baseconv.base62.decode(timestamp)
if max_age is not None:
if isinstance(max_age, datetime.timedelta):
max_age = max_age.total_seconds()
# Check timestamp is not older than max_age
age = time.time() - timestamp
if age > max_age:
raise SignatureExpired("Signature age %s > %s seconds" % (age, max_age))
return value