DO NOT REPLY [Bug 9653] New: - mod_rewrite example exception

[bu...@apache.org]

DO NOT REPLY TO THIS EMAIL, BUT PLEASE POST YOUR BUG 
RELATED COMMENTS THROUGH THE WEB INTERFACE AVAILABLE AT
<http://nagoya.apache.org/bugzilla/show_bug.cgi?id=9653>.
ANY REPLY MADE TO THIS MESSAGE WILL NOT BE COLLECTED AND 
INSERTED IN THE BUG DATABASE.

http://nagoya.apache.org/bugzilla/show_bug.cgi?id=9653

mod_rewrite example exception

           Summary: mod_rewrite example exception
           Product: Apache httpd-1.3
           Version: 1.3.23
          Platform: Other
               URL: http://httpd.apache.org/docs/misc/rewriteguide.html
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Documentation
        AssignedTo: bugs@httpd.apache.org
        ReportedBy: xxdpplus@yahoo.com


This bug is due to an unexpected behavior in MSIE
when using the referrer field deflector code to
deflect unwanted links by referrer.

As supplied on the Apache web site, at URL

http://httpd.apache.org/docs/misc/rewriteguide.html

the code looks like this:

RewriteMap  deflector txt:/path/to/deflector.map

           RewriteCond %{HTTP_REFERER} !=""
           RewriteCond ${deflector:%{HTTP_REFERER}} ^-$
           RewriteRule ^.* %{HTTP_REFERER} [R,L]

           RewriteCond %{HTTP_REFERER} !=""
           RewriteCond ${deflector:%{HTTP_REFERER}|NOT-FOUND} !=NOT-FOUND
           RewriteRule ^.* ${deflector:%{HTTP_REFERER}} [R,L]

           ##  deflector.map
           ##

           http://www.badguys.com/bad/index.html    -
           http://www.badguys.com/bad/index2.html   -
           http://www.badguys.com/bad/index3.html   http://somewhere.com/

The problem occurs when the deflected and the target page
reside on the same site.  It is due to (IMHO) an error in
MSIE, which does not dump its referrer field after the
redirection.  (Netscape, Lynx, Opera, etc. do not exhibit
this problem.)

MSIE comes in, with an offending referrer field, and is
deflected to a different URL on the same site.  It comes
back again *but does not dump the original referrer field*
and is deflected again, comes back again, is deflected
again, comes back again ... and loops infinitely.

I have a patch that I think might fix this, but I would
like to have your opinion before installing it.  It consists
of splitting the second ruleset as follows:

# The normal case; request URL != remapped URL

RewriteCond %{HTTP_REFERER} !=""
RewriteCond ^.* != deflector:%{HTTP_REFERER}
RewriteCond ${deflector:%{HTTP_REFERER}|NOT-FOUND} !=NOT-FOUND
RewriteRule ^.* ${deflector:%{HTTP_REFERER}} [R,L]

# When MSIE tries to loop; request URL = remapped URL

RewriteCond %{HTTP_REFERER} !=""
RewriteCond ^.* deflector:%{HTTP_REFERER}
RewriteCond ${deflector:%{HTTP_REFERER}|NOT-FOUND} !=NOT-FOUND
RewriteRule ^.* ${deflector:%{HTTP_REFERER}} [F]

In the first (the "normal") case, the request URL is
not the same as the remapped URL, and Apache issues
the remapped URL with a [R]edirect.  This will send it
off anywhere on the web.

In the second case, MSIE is trying to loop, has
already been through the first ruleset, and has been
redirected to the remapped URL.  Therefore, both original
and remapped pages reside on this server.  Apache
still issues the remapped URL, but as [F]inal
without a redirect.

I would be glad to have your opinion on this.

---------------------------------------------------------------------
To unsubscribe, e-mail: bugs-unsubscribe@httpd.apache.org
For additional commands, e-mail: bugs-help@httpd.apache.org