Source code for aiohttp.helpers

"""Various helper functions"""

import asyncio
import base64
import binascii
import cgi
import dataclasses
import datetime
import enum
import functools
import netrc
import os
import platform
import re
import sys
import time
import warnings
import weakref
from collections import namedtuple
from contextlib import suppress
from email.utils import parsedate
from http.cookies import SimpleCookie
from math import ceil
from pathlib import Path
from types import TracebackType
from typing import (
    Any,
    Callable,
    Dict,
    Generator,
    Generic,
    Iterable,
    Iterator,
    List,
    Mapping,
    Optional,
    Pattern,
    Tuple,
    Type,
    TypeVar,
    Union,
    cast,
)
from urllib.parse import quote
from urllib.request import getproxies, proxy_bypass

import async_timeout
from multidict import CIMultiDict, MultiDict, MultiDictProxy
from typing_extensions import Protocol, final
from yarl import URL

from . import hdrs
from .log import client_logger
from .typedefs import PathLike  # noqa

__all__ = ("BasicAuth", "ChainMapProxy", "ETag")

PY_38 = sys.version_info >= (3, 8)
PY_310 = sys.version_info >= (3, 10)

COOKIE_MAX_LENGTH = 4096

try:
    from typing import ContextManager
except ImportError:
    from typing_extensions import ContextManager


_T = TypeVar("_T")
_S = TypeVar("_S")

_SENTINEL = enum.Enum("_SENTINEL", "sentinel")
sentinel = _SENTINEL.sentinel

NO_EXTENSIONS = bool(os.environ.get("AIOHTTP_NO_EXTENSIONS"))  # type: bool

# N.B. sys.flags.dev_mode is available on Python 3.7+, use getattr
# for compatibility with older versions
DEBUG = getattr(sys.flags, "dev_mode", False) or (
    not sys.flags.ignore_environment and bool(os.environ.get("PYTHONASYNCIODEBUG"))
)  # type: bool


CHAR = {chr(i) for i in range(0, 128)}
CTL = {chr(i) for i in range(0, 32)} | {
    chr(127),
}
SEPARATORS = {
    "(",
    ")",
    "<",
    ">",
    "@",
    ",",
    ";",
    ":",
    "\\",
    '"',
    "/",
    "[",
    "]",
    "?",
    "=",
    "{",
    "}",
    " ",
    chr(9),
}
TOKEN = CHAR ^ CTL ^ SEPARATORS


class noop:
    def __await__(self) -> Generator[None, None, None]:
        yield


if PY_38:
    iscoroutinefunction = asyncio.iscoroutinefunction
else:

    def iscoroutinefunction(func: Any) -> bool:
        while isinstance(func, functools.partial):
            func = func.func
        return asyncio.iscoroutinefunction(func)


json_re = re.compile(r"(?:application/|[\w.-]+/[\w.+-]+?\+)json$", re.IGNORECASE)


[docs]class BasicAuth(namedtuple("BasicAuth", ["login", "password", "encoding"])): """Http basic authentication helper.""" def __new__( cls, login: str, password: str = "", encoding: str = "latin1" ) -> "BasicAuth": if login is None: raise ValueError("None is not allowed as login value") if password is None: raise ValueError("None is not allowed as password value") if ":" in login: raise ValueError('A ":" is not allowed in login (RFC 1945#section-11.1)') return super().__new__(cls, login, password, encoding)
[docs] @classmethod def decode(cls, auth_header: str, encoding: str = "latin1") -> "BasicAuth": """Create a BasicAuth object from an Authorization HTTP header.""" try: auth_type, encoded_credentials = auth_header.split(" ", 1) except ValueError: raise ValueError("Could not parse authorization header.") if auth_type.lower() != "basic": raise ValueError("Unknown authorization method %s" % auth_type) try: decoded = base64.b64decode( encoded_credentials.encode("ascii"), validate=True ).decode(encoding) except binascii.Error: raise ValueError("Invalid base64 encoding.") try: # RFC 2617 HTTP Authentication # https://www.ietf.org/rfc/rfc2617.txt # the colon must be present, but the username and password may be # otherwise blank. username, password = decoded.split(":", 1) except ValueError: raise ValueError("Invalid credentials.") return cls(username, password, encoding=encoding)
[docs] @classmethod def from_url(cls, url: URL, *, encoding: str = "latin1") -> Optional["BasicAuth"]: """Create BasicAuth from url.""" if not isinstance(url, URL): raise TypeError("url should be yarl.URL instance") if url.user is None: return None return cls(url.user, url.password or "", encoding=encoding)
[docs] def encode(self) -> str: """Encode credentials.""" creds = (f"{self.login}:{self.password}").encode(self.encoding) return "Basic %s" % base64.b64encode(creds).decode(self.encoding)
def strip_auth_from_url(url: URL) -> Tuple[URL, Optional[BasicAuth]]: auth = BasicAuth.from_url(url) if auth is None: return url, None else: return url.with_user(None), auth def netrc_from_env() -> Optional[netrc.netrc]: """Load netrc from file. Attempt to load it from the path specified by the env-var NETRC or in the default location in the user's home directory. Returns None if it couldn't be found or fails to parse. """ netrc_env = os.environ.get("NETRC") if netrc_env is not None: netrc_path = Path(netrc_env) else: try: home_dir = Path.home() except RuntimeError as e: # pragma: no cover # if pathlib can't resolve home, it may raise a RuntimeError client_logger.debug( "Could not resolve home directory when " "trying to look for .netrc file: %s", e, ) return None netrc_path = home_dir / ( "_netrc" if platform.system() == "Windows" else ".netrc" ) try: return netrc.netrc(str(netrc_path)) except netrc.NetrcParseError as e: client_logger.warning("Could not parse .netrc file: %s", e) except OSError as e: # we couldn't read the file (doesn't exist, permissions, etc.) if netrc_env or netrc_path.is_file(): # only warn if the environment wanted us to load it, # or it appears like the default file does actually exist client_logger.warning("Could not read .netrc file: %s", e) return None @dataclasses.dataclass(frozen=True) class ProxyInfo: proxy: URL proxy_auth: Optional[BasicAuth] def proxies_from_env() -> Dict[str, ProxyInfo]: proxy_urls = { k: URL(v) for k, v in getproxies().items() if k in ("http", "https", "ws", "wss") } netrc_obj = netrc_from_env() stripped = {k: strip_auth_from_url(v) for k, v in proxy_urls.items()} ret = {} for proto, val in stripped.items(): proxy, auth = val if proxy.scheme in ("https", "wss"): client_logger.warning( "%s proxies %s are not supported, ignoring", proxy.scheme.upper(), proxy ) continue if netrc_obj and auth is None: auth_from_netrc = None if proxy.host is not None: auth_from_netrc = netrc_obj.authenticators(proxy.host) if auth_from_netrc is not None: # auth_from_netrc is a (`user`, `account`, `password`) tuple, # `user` and `account` both can be username, # if `user` is None, use `account` *logins, password = auth_from_netrc login = logins[0] if logins[0] else logins[-1] auth = BasicAuth(cast(str, login), cast(str, password)) ret[proto] = ProxyInfo(proxy, auth) return ret def get_env_proxy_for_url(url: URL) -> Tuple[URL, Optional[BasicAuth]]: """Get a permitted proxy for the given URL from the env.""" if url.host is not None and proxy_bypass(url.host): raise LookupError(f"Proxying is disallowed for `{url.host!r}`") proxies_in_env = proxies_from_env() try: proxy_info = proxies_in_env[url.scheme] except KeyError: raise LookupError(f"No proxies found for `{url!s}` in the env") else: return proxy_info.proxy, proxy_info.proxy_auth @dataclasses.dataclass(frozen=True) class MimeType: type: str subtype: str suffix: str parameters: "MultiDictProxy[str]" @functools.lru_cache(maxsize=56) def parse_mimetype(mimetype: str) -> MimeType: """Parses a MIME type into its components. mimetype is a MIME type string. Returns a MimeType object. Example: >>> parse_mimetype('text/html; charset=utf-8') MimeType(type='text', subtype='html', suffix='', parameters={'charset': 'utf-8'}) """ if not mimetype: return MimeType( type="", subtype="", suffix="", parameters=MultiDictProxy(MultiDict()) ) parts = mimetype.split(";") params = MultiDict() # type: MultiDict[str] for item in parts[1:]: if not item: continue key, _, value = item.partition("=") params.add(key.lower().strip(), value.strip(' "')) fulltype = parts[0].strip().lower() if fulltype == "*": fulltype = "*/*" mtype, _, stype = fulltype.partition("/") stype, _, suffix = stype.partition("+") return MimeType( type=mtype, subtype=stype, suffix=suffix, parameters=MultiDictProxy(params) ) def guess_filename(obj: Any, default: Optional[str] = None) -> Optional[str]: name = getattr(obj, "name", None) if name and isinstance(name, str) and name[0] != "<" and name[-1] != ">": return Path(name).name return default not_qtext_re = re.compile(r"[^\041\043-\133\135-\176]") QCONTENT = {chr(i) for i in range(0x20, 0x7F)} | {"\t"} def quoted_string(content: str) -> str: """Return 7-bit content as quoted-string. Format content into a quoted-string as defined in RFC5322 for Internet Message Format. Notice that this is not the 8-bit HTTP format, but the 7-bit email format. Content must be in usascii or a ValueError is raised. """ if not (QCONTENT > set(content)): raise ValueError(f"bad content for quoted-string {content!r}") return not_qtext_re.sub(lambda x: "\\" + x.group(0), content) def content_disposition_header( disptype: str, quote_fields: bool = True, _charset: str = "utf-8", **params: str ) -> str: """Sets ``Content-Disposition`` header for MIME. This is the MIME payload Content-Disposition header from RFC 2183 and RFC 7579 section 4.2, not the HTTP Content-Disposition from RFC 6266. disptype is a disposition type: inline, attachment, form-data. Should be valid extension token (see RFC 2183) quote_fields performs value quoting to 7-bit MIME headers according to RFC 7578. Set to quote_fields to False if recipient can take 8-bit file names and field values. _charset specifies the charset to use when quote_fields is True. params is a dict with disposition params. """ if not disptype or not (TOKEN > set(disptype)): raise ValueError("bad content disposition type {!r}" "".format(disptype)) value = disptype if params: lparams = [] for key, val in params.items(): if not key or not (TOKEN > set(key)): raise ValueError( "bad content disposition parameter" " {!r}={!r}".format(key, val) ) if quote_fields: if key.lower() == "filename": qval = quote(val, "", encoding=_charset) lparams.append((key, '"%s"' % qval)) else: try: qval = quoted_string(val) except ValueError: qval = "".join( (_charset, "''", quote(val, "", encoding=_charset)) ) lparams.append((key + "*", qval)) else: lparams.append((key, '"%s"' % qval)) else: qval = val.replace("\\", "\\\\").replace('"', '\\"') lparams.append((key, '"%s"' % qval)) sparams = "; ".join("=".join(pair) for pair in lparams) value = "; ".join((value, sparams)) return value def is_expected_content_type( response_content_type: str, expected_content_type: str ) -> bool: """Checks if received content type is processable as an expected one. Both arguments should be given without parameters. """ if expected_content_type == "application/json": return json_re.match(response_content_type) is not None return expected_content_type in response_content_type class _TSelf(Protocol, Generic[_T]): _cache: Dict[str, _T] class reify(Generic[_T]): """Use as a class method decorator. It operates almost exactly like the Python `@property` decorator, but it puts the result of the method it decorates into the instance dict after the first call, effectively replacing the function it decorates with an instance variable. It is, in Python parlance, a data descriptor. """ def __init__(self, wrapped: Callable[..., _T]) -> None: self.wrapped = wrapped self.__doc__ = wrapped.__doc__ self.name = wrapped.__name__ def __get__(self, inst: _TSelf[_T], owner: Optional[Type[Any]] = None) -> _T: try: try: return inst._cache[self.name] except KeyError: val = self.wrapped(inst) inst._cache[self.name] = val return val except AttributeError: if inst is None: return self raise def __set__(self, inst: _TSelf[_T], value: _T) -> None: raise AttributeError("reified property is read-only") reify_py = reify try: from ._helpers import reify as reify_c if not NO_EXTENSIONS: reify = reify_c # type: ignore[misc,assignment] except ImportError: pass _ipv4_pattern = ( r"^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}" r"(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$" ) _ipv6_pattern = ( r"^(?:(?:(?:[A-F0-9]{1,4}:){6}|(?=(?:[A-F0-9]{0,4}:){0,6}" r"(?:[0-9]{1,3}\.){3}[0-9]{1,3}$)(([0-9A-F]{1,4}:){0,5}|:)" r"((:[0-9A-F]{1,4}){1,5}:|:)|::(?:[A-F0-9]{1,4}:){5})" r"(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}" r"(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])|(?:[A-F0-9]{1,4}:){7}" r"[A-F0-9]{1,4}|(?=(?:[A-F0-9]{0,4}:){0,7}[A-F0-9]{0,4}$)" r"(([0-9A-F]{1,4}:){1,7}|:)((:[0-9A-F]{1,4}){1,7}|:)|(?:[A-F0-9]{1,4}:){7}" r":|:(:[A-F0-9]{1,4}){7})$" ) _ipv4_regex = re.compile(_ipv4_pattern) _ipv6_regex = re.compile(_ipv6_pattern, flags=re.IGNORECASE) _ipv4_regexb = re.compile(_ipv4_pattern.encode("ascii")) _ipv6_regexb = re.compile(_ipv6_pattern.encode("ascii"), flags=re.IGNORECASE) def _is_ip_address( regex: Pattern[str], regexb: Pattern[bytes], host: Optional[Union[str, bytes]] ) -> bool: if host is None: return False if isinstance(host, str): return bool(regex.match(host)) elif isinstance(host, (bytes, bytearray, memoryview)): return bool(regexb.match(host)) else: raise TypeError(f"{host} [{type(host)}] is not a str or bytes") is_ipv4_address = functools.partial(_is_ip_address, _ipv4_regex, _ipv4_regexb) is_ipv6_address = functools.partial(_is_ip_address, _ipv6_regex, _ipv6_regexb) def is_ip_address(host: Optional[Union[str, bytes, bytearray, memoryview]]) -> bool: return is_ipv4_address(host) or is_ipv6_address(host) def next_whole_second() -> datetime.datetime: """Return current time rounded up to the next whole second.""" return datetime.datetime.now(datetime.timezone.utc).replace( microsecond=0 ) + datetime.timedelta(seconds=0) _cached_current_datetime = None # type: Optional[int] _cached_formatted_datetime = "" def rfc822_formatted_time() -> str: global _cached_current_datetime global _cached_formatted_datetime now = int(time.time()) if now != _cached_current_datetime: # Weekday and month names for HTTP date/time formatting; # always English! # Tuples are constants stored in codeobject! _weekdayname = ("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun") _monthname = ( "", # Dummy so we can use 1-based month numbers "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", ) year, month, day, hh, mm, ss, wd, *tail = time.gmtime(now) _cached_formatted_datetime = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % ( _weekdayname[wd], day, _monthname[month], year, hh, mm, ss, ) _cached_current_datetime = now return _cached_formatted_datetime def _weakref_handle(info: "Tuple[weakref.ref[object], str]") -> None: ref, name = info ob = ref() if ob is not None: with suppress(Exception): getattr(ob, name)() def weakref_handle( ob: object, name: str, timeout: float, loop: asyncio.AbstractEventLoop ) -> Optional[asyncio.TimerHandle]: if timeout is not None and timeout > 0: when = loop.time() + timeout if timeout >= 5: when = ceil(when) return loop.call_at(when, _weakref_handle, (weakref.ref(ob), name)) return None def call_later( cb: Callable[[], Any], timeout: float, loop: asyncio.AbstractEventLoop ) -> Optional[asyncio.TimerHandle]: if timeout is not None and timeout > 0: when = loop.time() + timeout if timeout > 5: when = ceil(when) return loop.call_at(when, cb) return None class TimeoutHandle: """Timeout handle""" def __init__( self, loop: asyncio.AbstractEventLoop, timeout: Optional[float] ) -> None: self._timeout = timeout self._loop = loop self._callbacks = ( [] ) # type: List[Tuple[Callable[..., None], Tuple[Any, ...], Dict[str, Any]]] def register( self, callback: Callable[..., None], *args: Any, **kwargs: Any ) -> None: self._callbacks.append((callback, args, kwargs)) def close(self) -> None: self._callbacks.clear() def start(self) -> Optional[asyncio.Handle]: timeout = self._timeout if timeout is not None and timeout > 0: when = self._loop.time() + timeout if timeout >= 5: when = ceil(when) return self._loop.call_at(when, self.__call__) else: return None def timer(self) -> "BaseTimerContext": if self._timeout is not None and self._timeout > 0: timer = TimerContext(self._loop) self.register(timer.timeout) return timer else: return TimerNoop() def __call__(self) -> None: for cb, args, kwargs in self._callbacks: with suppress(Exception): cb(*args, **kwargs) self._callbacks.clear() class BaseTimerContext(ContextManager["BaseTimerContext"]): pass class TimerNoop(BaseTimerContext): def __enter__(self) -> BaseTimerContext: return self def __exit__( self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> None: return class TimerContext(BaseTimerContext): """Low resolution timeout context manager""" def __init__(self, loop: asyncio.AbstractEventLoop) -> None: self._loop = loop self._tasks = [] # type: List[asyncio.Task[Any]] self._cancelled = False def __enter__(self) -> BaseTimerContext: task = asyncio.current_task(loop=self._loop) if task is None: raise RuntimeError( "Timeout context manager should be used " "inside a task" ) if self._cancelled: raise asyncio.TimeoutError from None self._tasks.append(task) return self def __exit__( self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> Optional[bool]: if self._tasks: self._tasks.pop() if exc_type is asyncio.CancelledError and self._cancelled: raise asyncio.TimeoutError from None return None def timeout(self) -> None: if not self._cancelled: for task in set(self._tasks): task.cancel() self._cancelled = True def ceil_timeout(delay: Optional[float]) -> async_timeout.Timeout: if delay is None or delay <= 0: return async_timeout.timeout(None) loop = asyncio.get_running_loop() now = loop.time() when = now + delay if delay > 5: when = ceil(when) return async_timeout.timeout_at(when) class HeadersMixin: __slots__ = ("_content_type", "_content_dict", "_stored_content_type") def __init__(self) -> None: super().__init__() self._content_type = None # type: Optional[str] self._content_dict = None # type: Optional[Dict[str, str]] self._stored_content_type: Union[str, _SENTINEL] = sentinel def _parse_content_type(self, raw: str) -> None: self._stored_content_type = raw if raw is None: # default value according to RFC 2616 self._content_type = "application/octet-stream" self._content_dict = {} else: self._content_type, self._content_dict = cgi.parse_header(raw) @property def content_type(self) -> str: """The value of content part for Content-Type HTTP header.""" raw = self._headers.get(hdrs.CONTENT_TYPE) # type: ignore[attr-defined] if self._stored_content_type != raw: self._parse_content_type(raw) return self._content_type # type: ignore[return-value] @property def charset(self) -> Optional[str]: """The value of charset part for Content-Type HTTP header.""" raw = self._headers.get(hdrs.CONTENT_TYPE) # type: ignore[attr-defined] if self._stored_content_type != raw: self._parse_content_type(raw) return self._content_dict.get("charset") # type: ignore[union-attr] @property def content_length(self) -> Optional[int]: """The value of Content-Length HTTP header.""" content_length = self._headers.get( # type: ignore[attr-defined] hdrs.CONTENT_LENGTH ) if content_length is not None: return int(content_length) else: return None def set_result(fut: "asyncio.Future[_T]", result: _T) -> None: if not fut.done(): fut.set_result(result) def set_exception(fut: "asyncio.Future[_T]", exc: BaseException) -> None: if not fut.done(): fut.set_exception(exc)
[docs]@final class ChainMapProxy(Mapping[str, Any]): __slots__ = ("_maps",) def __init__(self, maps: Iterable[Mapping[str, Any]]) -> None: self._maps = tuple(maps) def __init_subclass__(cls) -> None: raise TypeError( "Inheritance class {} from ChainMapProxy " "is forbidden".format(cls.__name__) ) def __getitem__(self, key: str) -> Any: for mapping in self._maps: try: return mapping[key] except KeyError: pass raise KeyError(key) def get(self, key: str, default: Any = None) -> Any: return self[key] if key in self else default def __len__(self) -> int: # reuses stored hash values if possible return len(set().union(*self._maps)) # type: ignore[arg-type] def __iter__(self) -> Iterator[str]: d = {} # type: Dict[str, Any] for mapping in reversed(self._maps): # reuses stored hash values if possible d.update(mapping) return iter(d) def __contains__(self, key: object) -> bool: return any(key in m for m in self._maps) def __bool__(self) -> bool: return any(self._maps) def __repr__(self) -> str: content = ", ".join(map(repr, self._maps)) return f"ChainMapProxy({content})"
class CookieMixin: def __init__(self) -> None: super().__init__() self._cookies = SimpleCookie() # type: SimpleCookie[str] @property def cookies(self) -> "SimpleCookie[str]": return self._cookies def set_cookie( self, name: str, value: str, *, expires: Optional[str] = None, domain: Optional[str] = None, max_age: Optional[Union[int, str]] = None, path: str = "/", secure: Optional[bool] = None, httponly: Optional[bool] = None, version: Optional[str] = None, samesite: Optional[str] = None, ) -> None: """Set or update response cookie. Sets new cookie or updates existent with new value. Also updates only those params which are not None. """ old = self._cookies.get(name) if old is not None and old.coded_value == "": # deleted cookie self._cookies.pop(name, None) self._cookies[name] = value c = self._cookies[name] if expires is not None: c["expires"] = expires elif c.get("expires") == "Thu, 01 Jan 1970 00:00:00 GMT": del c["expires"] if domain is not None: c["domain"] = domain if max_age is not None: c["max-age"] = str(max_age) elif "max-age" in c: del c["max-age"] c["path"] = path if secure is not None: c["secure"] = secure if httponly is not None: c["httponly"] = httponly if version is not None: c["version"] = version if samesite is not None: c["samesite"] = samesite if DEBUG: cookie_length = len(c.output(header="")[1:]) if cookie_length > COOKIE_MAX_LENGTH: warnings.warn( "The size of is too large, it might get ignored by the client.", UserWarning, stacklevel=2, ) def del_cookie( self, name: str, *, domain: Optional[str] = None, path: str = "/" ) -> None: """Delete cookie. Creates new empty expired cookie. """ # TODO: do we need domain/path here? self._cookies.pop(name, None) self.set_cookie( name, "", max_age=0, expires="Thu, 01 Jan 1970 00:00:00 GMT", domain=domain, path=path, ) def populate_with_cookies( headers: "CIMultiDict[str]", cookies: "SimpleCookie[str]" ) -> None: for cookie in cookies.values(): value = cookie.output(header="")[1:] headers.add(hdrs.SET_COOKIE, value) # https://tools.ietf.org/html/rfc7232#section-2.3 _ETAGC = r"[!#-}\x80-\xff]+" _ETAGC_RE = re.compile(_ETAGC) _QUOTED_ETAG = fr'(W/)?"({_ETAGC})"' QUOTED_ETAG_RE = re.compile(_QUOTED_ETAG) LIST_QUOTED_ETAG_RE = re.compile(fr"({_QUOTED_ETAG})(?:\s*,\s*|$)|(.)") ETAG_ANY = "*"
[docs]@dataclasses.dataclass(frozen=True) class ETag: value: str is_weak: bool = False
def validate_etag_value(value: str) -> None: if value != ETAG_ANY and not _ETAGC_RE.fullmatch(value): raise ValueError( f"Value {value!r} is not a valid etag. Maybe it contains '\"'?" ) def parse_http_date(date_str: Optional[str]) -> Optional[datetime.datetime]: """Process a date string, return a datetime object""" if date_str is not None: timetuple = parsedate(date_str) if timetuple is not None: with suppress(ValueError): return datetime.datetime(*timetuple[:6], tzinfo=datetime.timezone.utc) return None