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

   1 import base64
   2 import string
   3 import struct
   4 import typing as _t
   5
   6 from .exc import BadData
   7
   8 _t_str_bytes = _t.Union[str, bytes]
   9
  10
  11 def want_bytes(
  12     s: _t_str_bytes, encoding: str = "utf-8", errors: str = "strict"
  13 ) -> bytes:
  14     if isinstance(s, str):
  15         s = s.encode(encoding, errors)
  16
  17     return s
  18
  19
  20 def base64_encode(string: _t_str_bytes) -> bytes:
  21     """Base64 encode a string of bytes or text. The resulting bytes are
  22     safe to use in URLs.
  23     """
  24     string = want_bytes(string)
  25     return base64.urlsafe_b64encode(string).rstrip(b"=")
  26
  27
  28 def base64_decode(string: _t_str_bytes) -> bytes:
  29     """Base64 decode a URL-safe string of bytes or text. The result is
  30     bytes.
  31     """
  32     string = want_bytes(string, encoding="ascii", errors="ignore")
  33     string += b"=" * (-len(string) % 4)
  34
  35     try:
  36         return base64.urlsafe_b64decode(string)
  37     except (TypeError, ValueError) as e:
  38         raise BadData("Invalid base64-encoded data") from e
  39
  40
  41 # The alphabet used by base64.urlsafe_*
  42 _base64_alphabet = f"{string.ascii_letters}{string.digits}-_=".encode("ascii")
  43
  44 _int64_struct = struct.Struct(">Q")
  45 _int_to_bytes = _int64_struct.pack
  46 _bytes_to_int = _t.cast("_t.Callable[[bytes], _t.Tuple[int]]", _int64_struct.unpack)
  47
  48
  49 def int_to_bytes(num: int) -> bytes:
  50     return _int_to_bytes(num).lstrip(b"\x00")
  51
  52
  53 def bytes_to_int(bytestr: bytes) -> int:
  54     return _bytes_to_int(bytestr.rjust(8, b"\x00"))[0]