Subject: Re: WWW Form Bug Report: "can't retrieve real document if error doc
 is newer" on BSDI (fwd)
To: new-httpd@hyperreal.com
Date: Fri, 22 Sep 1995 18:09:25 +0100 (BST)
From: Ben Laurie <ben@gonzo.ben.algroup.co.uk>
In-Reply-To: <199509221711.KAA05430@taz.hyperreal.com> from "Rob Hartill" at
 Sep 22, 95 10:11:19 am
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> 
> 
> I think the following can be fixed by discarding IMS when redirecting
> to an ErrorDocument...

I don't think so, what seems to be happening is that Netscape is cacheing the
error document as the image for another URL, so when that _other_ URL is
called again, Netscape offers up the cached image. The correct procedure
would be as he suggests: either send a no-cache pragma, or a very short
expiry. Unfortunately, this may not work either, as Netscape seems to be
brain-damaged about both cache expiry and no-cache pragma (at least, some
experiments I have done with client pull have required me to disable Netscape's
cache to see updates).

On second thoughts, a short expiry is also wrong. It needs to be an expiry
that is before the date of the real document. But it might as well be a
no-cache, in that case.

> 
> Ack sent to submitter.
> 
> Forwarded message:
> > From nobody@hyperreal.com  Fri Sep 22 08:53:51 1995
> > Message-Id: <199509221553.IAA28800@taz.hyperreal.com>
> > From: khera@kciLink.com
> > To: apache-bugs%apache.org@organic.com
> > Date: Fri Sep 22  8:53:44 1995
> > Subject: WWW Form Bug Report: "can't retrieve real document if error doc is newer" on BSDI
> > 
> > Submitter: khera@kciLink.com
> > Operating system: BSDI, version: 
> > Extra Modules used: mSQL

BTW - what's this       ^^^^ ?

> > URL exhibiting problem: http://www.govcon.com/information/events.html
> > 
> > Symptoms:
> > --
> > Given:  ErrorDocument 403 /members-only.html  if the document members-only.html is newer than the document which caused the error, you can no longer retrieve the original document even when the error is corrected, if your browser uses the "if-modified-since" request, eg, Netscape.  To see the error in action, visit the URL below while running Netscape Navigator.  When it asks for user ID, just hit "cancel" and you will be presented with the members-only.html document.  However, the client still thinks this is the original document name.  Now, open that URL again.  You will not be asked for an ID at all but dropped right into the error document.  I believe that any error document shipped out should either have a very short Expires header, or should have a no-cache pragma so that the browsers don't cache the files.  To see the actual file, use the User ID "guest" and the password "guest". Visit the directory URL (without the "events.html" file name to see the whole directory!
>  . !
> >  You will then be asked for the user ID and password.  From there, scoll down and click on "upcoming events".  Even though you are authenticated now, you will not get the real document, but the error document.  There is no way short of purging your entire cache to get at the real document.  
> > --
> > 
> > Backtrace:
> > --
> > 
> > --
> > 
> 

-- 
Ben Laurie                  Phone: +44 (181) 994 6435
Freelance Consultant        Fax:   +44 (181) 994 6472
and Technical Director      Email: ben@algroup.co.uk (preferred)
A.L. Digital Ltd,                  benl@fear.demon.co.uk (backup)
London, England.

[Note for the paranoid: "fear" as in "Fear and Loathing
in Las Vegas", "demon" as in Demon Internet Services, a
commercial Internet access provider.]