Parser incorrectly parses years in some cases

[except]

Consider the following Set-Cookie header -
foo=bar; expires=Thu, 10-Sep-20 20:00:00 GMT;

This should be parsed as 2020-09-10 20:00 +0 however expires returns 0020-09-10 20:00 +0

[jhpratt]

After a quick discussion, this behavior is correct as intended on time's end — the century will not be assumed.

Apparently this originates from Cloudflare, which isn't actually following the spec (emphasis mine)

HTTP/1.1 clients and servers that parse the date value MUST accept
all three formats (for compatibility with HTTP/1.0), though they MUST
only generate the RFC 1123 format for representing HTTP-date values
in header fields.

The first part of that doesn't actually specify what should happen when encountering a two-digit year, though I can't find anything along those lines in any RFC. As such, I think it's best to follow browsers' behavior. Apparently Chrome uses the following code (@except can you provide a source?)

// Normalize the year to expand abbreviated years to the full year.
if (exploded.year >= 69 && exploded.year <= 99)
  exploded.year += 1900;
if (exploded.year >= 0 && exploded.year <= 68)
  exploded.year += 2000;

This essentially assumes the year is between 1969 and 2068 inclusive.

Unfortunately, the only way to adjust the year is to fully reconstruct a PrimitiveDateTime from its components. Having a better API for operations along these lines is tracked in time-rs/time#256.

[except]

Source to where Chromium corrects two-digit based years.

[jhpratt]

For the record: I have just submitted a request to Cloudflare. Regardless, this crate's behavior is also not spec compliant.

[except]

Firefox uses PR_ParseTimeString (PR_ParseTimeStringToExplodedTime) which does something similar when parsing.

year = n1;
if (year < 70) {
    year += 2000;
}
else if (year < 100) {
    year += 1900;
}

WebKit using parseExpiresMS (WTF::parseDateFromNullTerminatedCharacter) also parses slightly differently.

if (year) {
    int yearValue = year.value();
    if (yearValue >= 0 && yearValue < 100) {
        if (yearValue < 50)
            yearValue += 2000;
        else
            yearValue += 1900;
    }
    year = yearValue;
}

[SergioBenitez]

Thank you for the input, all!