venv/lib/python3.11/site-packages/itsdangerous/url_safe.py

   1 import typing as _t
   2 import zlib
   3
   4 from ._json import _CompactJSON
   5 from .encoding import base64_decode
   6 from .encoding import base64_encode
   7 from .exc import BadPayload
   8 from .serializer import Serializer
   9 from .timed import TimedSerializer
  10
  11
  12 class URLSafeSerializerMixin(Serializer):
  13     """Mixed in with a regular serializer it will attempt to zlib
  14     compress the string to make it shorter if necessary. It will also
  15     base64 encode the string so that it can safely be placed in a URL.
  16     """
  17
  18     default_serializer = _CompactJSON
  19
  20     def load_payload(
  21         self,
  22         payload: bytes,
  23         *args: _t.Any,
  24         serializer: _t.Optional[_t.Any] = None,
  25         **kwargs: _t.Any,
  26     ) -> _t.Any:
  27         decompress = False
  28
  29         if payload.startswith(b"."):
  30             payload = payload[1:]
  31             decompress = True
  32
  33         try:
  34             json = base64_decode(payload)
  35         except Exception as e:
  36             raise BadPayload(
  37                 "Could not base64 decode the payload because of an exception",
  38                 original_error=e,
  39             ) from e
  40
  41         if decompress:
  42             try:
  43                 json = zlib.decompress(json)
  44             except Exception as e:
  45                 raise BadPayload(
  46                     "Could not zlib decompress the payload before decoding the payload",
  47                     original_error=e,
  48                 ) from e
  49
  50         return super().load_payload(json, *args, **kwargs)
  51
  52     def dump_payload(self, obj: _t.Any) -> bytes:
  53         json = super().dump_payload(obj)
  54         is_compressed = False
  55         compressed = zlib.compress(json)
  56
  57         if len(compressed) < (len(json) - 1):
  58             json = compressed
  59             is_compressed = True
  60
  61         base64d = base64_encode(json)
  62
  63         if is_compressed:
  64             base64d = b"." + base64d
  65
  66         return base64d
  67
  68
  69 class URLSafeSerializer(URLSafeSerializerMixin, Serializer):
  70     """Works like :class:`.Serializer` but dumps and loads into a URL
  71     safe string consisting of the upper and lowercase character of the
  72     alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
  73     """
  74
  75
  76 class URLSafeTimedSerializer(URLSafeSerializerMixin, TimedSerializer):
  77     """Works like :class:`.TimedSerializer` but dumps and loads into a
  78     URL safe string consisting of the upper and lowercase character of
  79     the alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
  80     """