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bug#10147: HTTP "Expires" header should handle non-date values
From: |
Andy Wingo |
Subject: |
bug#10147: HTTP "Expires" header should handle non-date values |
Date: |
Wed, 21 Dec 2011 21:51:04 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) |
Hi Daniel,
So sorry for the delay.
On Sun 27 Nov 2011 05:39, Daniel Hartwig <address@hidden> writes:
> This is definitely a bug on Guile's part, HTTP/1.1 permits such values
> for "Expires" headers [1], treating them as though they were a date in
> the past:
>
> HTTP/1.1 clients and caches MUST treat other invalid date formats,
> especially including the value "0", as in the past (i.e., "already
> expired").
>
> [1] http://tools.ietf.org/html/rfc2616#section-14.21
But that's right after saying
The format is an absolute date and time as defined by HTTP-date in
section 3.3.1; it MUST be in RFC 1123 date format:
Expires = "Expires" ":" HTTP-date
But, pragmatism may rule, here...
> Attached patch permits non-date values for "Expires", leaving them as
> strings (preferable, as such responses can be transparently forwarded
> to other clients). The staleness of a response could be determined
> quite crudely, e.g.
>
> (define (response-stale? r)
> (let ((expires (response-expires r)))
> (and expires
> (or (not (date? expires)) ;; Indicates already expired.
> (time<=? (date->time-utc expires)
> (current-time))))))
Let us assume that it is a good idea to include this hack. Wouldn't it
be better to keep the expires header as a date? Would any date in the
past work fine?
Would it be best to allow some special cases like "0" or "-1" instead?
I'm just trying to limit the damage here :) WDYT?
Andy
--
http://wingolog.org/
- bug#10147: HTTP "Expires" header should handle non-date values,
Andy Wingo <=