[users@httpd] mod_rewrite: PATH_INFO gets injected with each Rule

[Aleksander Budzynowski <bu...@gmail.com>]

Hi,

The behaviour I'm seeing resemebles the bug described here:
http://archive.apache.org/gnats/7879 Reportedly it was fixed in
2.0.30.However, testing under both 2.2.3 and 2.0.61 I get the same
sort of problem.

Essentially, PATH_INFO is appended to the end of the URI before each
RewriteRule is processed. If more than one RewriteRule match, you can end up
with redundant garbage at the end of the URI.

Let's consider a rule designed to turn all underscores into hyphens (done in
a per-directory context, i.e. .htaccess file):

RewriteEngine On
#Convert _ to - (N flag ensures that all underscores get converted)
RewriteRule ^(.*)_(.*) $1-$2 [N]

It seems innocent enough. But issue a request for

/_f_o_o_/bar

(where _f_o_o_ does not exist, placing '/bar' in PATH_INFO), and this gets
rewritten to /-f-o-o-/bar/bar/bar/bar!

If you request /foo/_bar (assuming foo does not exist), then each new _bar
will feed an extra underscore back into the mix, creating an infinite loop -
even worse.


In the RewriteLog, one sees something like this before the application of
each RewriteRule:

add path-info postfix: /rewritebase/_f_o_o_ -> /rewritebase/_f_o_o_/bar

although each time it accumulates an extra '/bar'.


This doesn't look right to me. Is it a bug? Or have I missed something
obvious?

Thanks,

Aleks

Re: [users@httpd] mod_rewrite: PATH_INFO gets injected with each Rule

[Rich Bowen <rb...@rcbowen.com>]

On Apr 21, 2008, at 08:54, Aleksander Budzynowski wrote:

> Hi,
>
> The behaviour I'm seeing resemebles the bug described here: http:// 
> archive.apache.org/gnats/7879 Reportedly it was fixed in 2.0.30.  
> However, testing under both 2.2.3 and 2.0.61 I get the same sort of  
> problem.
>
> Essentially, PATH_INFO is appended to the end of the URI before  
> each RewriteRule is processed. If more than one RewriteRule match,  
> you can end up with redundant garbage at the end of the URI.
>
> Let's consider a rule designed to turn all underscores into hyphens  
> (done in a per-directory context, i.e. .htaccess file):
>
> RewriteEngine On
> #Convert _ to - (N flag ensures that all underscores get converted)
> RewriteRule ^(.*)_(.*) $1-$2 [N]
>
> It seems innocent enough. But issue a request for
>
> /_f_o_o_/bar
>
> (where _f_o_o_ does not exist, placing '/bar' in PATH_INFO), and  
> this gets rewritten to /-f-o-o-/bar/bar/bar/bar!
>
> If you request /foo/_bar (assuming foo does not exist), then each  
> new _bar will feed an extra underscore back into the mix, creating  
> an infinite loop - even worse.
>
>
> In the RewriteLog, one sees something like this before the  
> application of each RewriteRule:
>
> add path-info postfix: /rewritebase/_f_o_o_ -> /rewritebase/_f_o_o_/ 
> bar
>
> although each time it accumulates an extra '/bar'.
>
>
> This doesn't look right to me. Is it a bug? Or have I missed  
> something obvious?



This does look pretty nasty. Can you try 1) testing with the latest  
versions, and 2) posting your RewriteLog so that we can see what  
process it's going through to do this? Given that that's an example  
from the documentation, one kind of hopes that it'll work correctly.

Also, I'm trying this out myself. Is it only on PATH_INFO, or is it  
also on existing file names?

--Rich

--
Just because your voice reaches halfway around the world doesn't mean  
you are wiser than when it reached only to the end of the bar.
Edward R. Murrow