229 lines
7.9 KiB
Python
229 lines
7.9 KiB
Python
|
from __future__ import annotations
|
||
|
|
|
||
|
|
import collections.abc as cabc
|
||
|
|
import time
|
||
|
|
import typing as t
|
||
|
|
from datetime import datetime
|
||
|
|
from datetime import timezone
|
||
|
|
|
||
|
|
from .encoding import base64_decode
|
||
|
|
from .encoding import base64_encode
|
||
|
|
from .encoding import bytes_to_int
|
||
|
|
from .encoding import int_to_bytes
|
||
|
|
from .encoding import want_bytes
|
||
|
|
from .exc import BadSignature
|
||
|
|
from .exc import BadTimeSignature
|
||
|
|
from .exc import SignatureExpired
|
||
|
|
from .serializer import _TSerialized
|
||
|
|
from .serializer import Serializer
|
||
|
|
from .signer import Signer
|
||
|
|
|
||
|
|
|
||
|
|
class TimestampSigner(Signer):
|
||
|
|
"""Works like the regular :class:`.Signer` but also records the time
|
||
|
|
of the signing and can be used to expire signatures. The
|
||
|
|
:meth:`unsign` method can raise :exc:`.SignatureExpired` if the
|
||
|
|
unsigning failed because the signature is expired.
|
||
|
|
"""
|
||
|
|
|
||
|
|
def get_timestamp(self) -> int:
|
||
|
|
"""Returns the current timestamp. The function must return an
|
||
|
|
integer.
|
||
|
|
"""
|
||
|
|
return int(time.time())
|
||
|
|
|
||
|
|
def timestamp_to_datetime(self, ts: int) -> datetime:
|
||
|
|
"""Convert the timestamp from :meth:`get_timestamp` into an
|
||
|
|
aware :class`datetime.datetime` in UTC.
|
||
|
|
|
||
|
|
.. versionchanged:: 2.0
|
||
|
|
The timestamp is returned as a timezone-aware ``datetime``
|
||
|
|
in UTC rather than a naive ``datetime`` assumed to be UTC.
|
||
|
|
"""
|
||
|
|
return datetime.fromtimestamp(ts, tz=timezone.utc)
|
||
|
|
|
||
|
|
def sign(self, value: str | bytes) -> bytes:
|
||
|
|
"""Signs the given string and also attaches time information."""
|
||
|
|
value = want_bytes(value)
|
||
|
|
timestamp = base64_encode(int_to_bytes(self.get_timestamp()))
|
||
|
|
sep = want_bytes(self.sep)
|
||
|
|
value = value + sep + timestamp
|
||
|
|
return value + sep + self.get_signature(value)
|
||
|
|
|
||
|
|
# Ignore overlapping signatures check, return_timestamp is the only
|
||
|
|
# parameter that affects the return type.
|
||
|
|
|
||
|
|
@t.overload
|
||
|
|
def unsign( # type: ignore[overload-overlap]
|
||
|
|
self,
|
||
|
|
signed_value: str | bytes,
|
||
|
|
max_age: int | None = None,
|
||
|
|
return_timestamp: t.Literal[False] = False,
|
||
|
|
) -> bytes: ...
|
||
|
|
|
||
|
|
@t.overload
|
||
|
|
def unsign(
|
||
|
|
self,
|
||
|
|
signed_value: str | bytes,
|
||
|
|
max_age: int | None = None,
|
||
|
|
return_timestamp: t.Literal[True] = True,
|
||
|
|
) -> tuple[bytes, datetime]: ...
|
||
|
|
|
||
|
|
def unsign(
|
||
|
|
self,
|
||
|
|
signed_value: str | bytes,
|
||
|
|
max_age: int | None = None,
|
||
|
|
return_timestamp: bool = False,
|
||
|
|
) -> tuple[bytes, datetime] | bytes:
|
||
|
|
"""Works like the regular :meth:`.Signer.unsign` but can also
|
||
|
|
validate the time. See the base docstring of the class for
|
||
|
|
the general behavior. If ``return_timestamp`` is ``True`` the
|
||
|
|
timestamp of the signature will be returned as an aware
|
||
|
|
:class:`datetime.datetime` object in UTC.
|
||
|
|
|
||
|
|
.. versionchanged:: 2.0
|
||
|
|
The timestamp is returned as a timezone-aware ``datetime``
|
||
|
|
in UTC rather than a naive ``datetime`` assumed to be UTC.
|
||
|
|
"""
|
||
|
|
try:
|
||
|
|
result = super().unsign(signed_value)
|
||
|
|
sig_error = None
|
||
|
|
except BadSignature as e:
|
||
|
|
sig_error = e
|
||
|
|
result = e.payload or b""
|
||
|
|
|
||
|
|
sep = want_bytes(self.sep)
|
||
|
|
|
||
|
|
# If there is no timestamp in the result there is something
|
||
|
|
# seriously wrong. In case there was a signature error, we raise
|
||
|
|
# that one directly, otherwise we have a weird situation in
|
||
|
|
# which we shouldn't have come except someone uses a time-based
|
||
|
|
# serializer on non-timestamp data, so catch that.
|
||
|
|
if sep not in result:
|
||
|
|
if sig_error:
|
||
|
|
raise sig_error
|
||
|
|
|
||
|
|
raise BadTimeSignature("timestamp missing", payload=result)
|
||
|
|
|
||
|
|
value, ts_bytes = result.rsplit(sep, 1)
|
||
|
|
ts_int: int | None = None
|
||
|
|
ts_dt: datetime | None = None
|
||
|
|
|
||
|
|
try:
|
||
|
|
ts_int = bytes_to_int(base64_decode(ts_bytes))
|
||
|
|
except Exception:
|
||
|
|
pass
|
||
|
|
|
||
|
|
# Signature is *not* okay. Raise a proper error now that we have
|
||
|
|
# split the value and the timestamp.
|
||
|
|
if sig_error is not None:
|
||
|
|
if ts_int is not None:
|
||
|
|
try:
|
||
|
|
ts_dt = self.timestamp_to_datetime(ts_int)
|
||
|
|
except (ValueError, OSError, OverflowError) as exc:
|
||
|
|
# Windows raises OSError
|
||
|
|
# 32-bit raises OverflowError
|
||
|
|
raise BadTimeSignature(
|
||
|
|
"Malformed timestamp", payload=value
|
||
|
|
) from exc
|
||
|
|
|
||
|
|
raise BadTimeSignature(str(sig_error), payload=value, date_signed=ts_dt)
|
||
|
|
|
||
|
|
# Signature was okay but the timestamp is actually not there or
|
||
|
|
# malformed. Should not happen, but we handle it anyway.
|
||
|
|
if ts_int is None:
|
||
|
|
raise BadTimeSignature("Malformed timestamp", payload=value)
|
||
|
|
|
||
|
|
# Check timestamp is not older than max_age
|
||
|
|
if max_age is not None:
|
||
|
|
age = self.get_timestamp() - ts_int
|
||
|
|
|
||
|
|
if age > max_age:
|
||
|
|
raise SignatureExpired(
|
||
|
|
f"Signature age {age} > {max_age} seconds",
|
||
|
|
payload=value,
|
||
|
|
date_signed=self.timestamp_to_datetime(ts_int),
|
||
|
|
)
|
||
|
|
|
||
|
|
if age < 0:
|
||
|
|
raise SignatureExpired(
|
||
|
|
f"Signature age {age} < 0 seconds",
|
||
|
|
payload=value,
|
||
|
|
date_signed=self.timestamp_to_datetime(ts_int),
|
||
|
|
)
|
||
|
|
|
||
|
|
if return_timestamp:
|
||
|
|
return value, self.timestamp_to_datetime(ts_int)
|
||
|
|
|
||
|
|
return value
|
||
|
|
|
||
|
|
def validate(self, signed_value: str | bytes, max_age: int | None = None) -> bool:
|
||
|
|
"""Only validates the given signed value. Returns ``True`` if
|
||
|
|
the signature exists and is valid."""
|
||
|
|
try:
|
||
|
|
self.unsign(signed_value, max_age=max_age)
|
||
|
|
return True
|
||
|
|
except BadSignature:
|
||
|
|
return False
|
||
|
|
|
||
|
|
|
||
|
|
class TimedSerializer(Serializer[_TSerialized]):
|
||
|
|
"""Uses :class:`TimestampSigner` instead of the default
|
||
|
|
:class:`.Signer`.
|
||
|
|
"""
|
||
|
|
|
||
|
|
default_signer: type[TimestampSigner] = TimestampSigner
|
||
|
|
|
||
|
|
def iter_unsigners(
|
||
|
|
self, salt: str | bytes | None = None
|
||
|
|
) -> cabc.Iterator[TimestampSigner]:
|
||
|
|
return t.cast("cabc.Iterator[TimestampSigner]", super().iter_unsigners(salt))
|
||
|
|
|
||
|
|
# TODO: Signature is incompatible because parameters were added
|
||
|
|
# before salt.
|
||
|
|
|
||
|
|
def loads( # type: ignore[override]
|
||
|
|
self,
|
||
|
|
s: str | bytes,
|
||
|
|
max_age: int | None = None,
|
||
|
|
return_timestamp: bool = False,
|
||
|
|
salt: str | bytes | None = None,
|
||
|
|
) -> t.Any:
|
||
|
|
"""Reverse of :meth:`dumps`, raises :exc:`.BadSignature` if the
|
||
|
|
signature validation fails. If a ``max_age`` is provided it will
|
||
|
|
ensure the signature is not older than that time in seconds. In
|
||
|
|
case the signature is outdated, :exc:`.SignatureExpired` is
|
||
|
|
raised. All arguments are forwarded to the signer's
|
||
|
|
:meth:`~TimestampSigner.unsign` method.
|
||
|
|
"""
|
||
|
|
s = want_bytes(s)
|
||
|
|
last_exception = None
|
||
|
|
|
||
|
|
for signer in self.iter_unsigners(salt):
|
||
|
|
try:
|
||
|
|
base64d, timestamp = signer.unsign(
|
||
|
|
s, max_age=max_age, return_timestamp=True
|
||
|
|
)
|
||
|
|
payload = self.load_payload(base64d)
|
||
|
|
|
||
|
|
if return_timestamp:
|
||
|
|
return payload, timestamp
|
||
|
|
|
||
|
|
return payload
|
||
|
|
except SignatureExpired:
|
||
|
|
# The signature was unsigned successfully but was
|
||
|
|
# expired. Do not try the next signer.
|
||
|
|
raise
|
||
|
|
except BadSignature as err:
|
||
|
|
last_exception = err
|
||
|
|
|
||
|
|
raise t.cast(BadSignature, last_exception)
|
||
|
|
|
||
|
|
def loads_unsafe( # type: ignore[override]
|
||
|
|
self,
|
||
|
|
s: str | bytes,
|
||
|
|
max_age: int | None = None,
|
||
|
|
salt: str | bytes | None = None,
|
||
|
|
) -> tuple[bool, t.Any]:
|
||
|
|
return self._loads_unsafe_impl(s, salt, load_kwargs={"max_age": max_age})
|