http.cookies.BaseCookie[1] can't parse Expires in this format like Expires=Thu,31 Jan 2019 05:56:00 GMT;(Less space after Thu,).

I encountered this problem in actual use, Chrome, IE and Firefox can parse this string normally. Many languages, such as JavaScript, can also parse this data automatically.

I built a test site using Flask: https://paste.ubuntu.com/p/K7Z4K4KH7Z/, Use curl and requests to get cookies correctly, but not with aiohttp (because it uses http.cookies.BaseCookie).

Looking at MDN[2] and rfc[3](Thanks tirkarthi), this doesn't seem to be a canonical behavior, But some Java WEB frameworks will produce this behavior (such as the one that caused me to find the problem).

This problem can be solved by modifying a regular expression[4], but I don't know if it should be compatible with this non-standard way of writing.

English is not my native language; please excuse typing errors.


[1] https://github.com/python/cpython/blob/master/Lib/http/cookies.py#L457
[2] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie#Directives
[3] https://tools.ietf.org/html/rfc6265#section-4.1.1
[4] https://github.com/python/cpython/blob/master/Lib/http/cookies.py#L444