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From Shawn Parr <>
Subject [users@httpd] Reverse Proxy and escaped characters in 2.2.8
Date Mon, 26 Jan 2009 17:37:43 GMT
I'm having an issue with a reverse proxy setup using Apache 2.2.8 on  
Ubuntu server 8.04.1.

Some software is sending out links using escaped characters,  
specifically %2F for /.  When it goes through the proxy those get re- 
escaped to %252F due to the proxy adding the escape sequence for the  
percent sign.

I see a few bugs for similar issues in the apache bugzilla, however  
the ones I have found so far seem to be for past versions, and all  
claim to be fixed.

I tried adding the nocanon flag to my ProxyPass directive, but the  
characters where still being improperly escaped, and it caused more  
errors down the line due to the bug where parameter strings are  
duplicated (#44730).

Basically my setup is like this:

ProxyPass / http://<internal server>/
ProxyHTMLURLMap http://<internal server> http://<external server/rev  

<Location />
ProxyPassReverse http://<internal server>/
SetOutputFilter proxy-html
ProxyHTMLURLMap / /

I temporarily removed the mod_proxy_html directives, and the issue  
didn't change, so I'm fairly sure I can rule it out as a culprit.

As mentioned above changing the first line to:

ProxyPass / http://<internal server>/ nocanon

Still displays the problem.

The software we are using is a php application called SilverStripe.   
This issue springs up in a lot of locations, however the most obvious  
is when trying to log in.  It passes a URL like:  http://<server>/ 
Security/login/?BackURL=%2Fadmin%2F which is then converted at the  
reverse proxy to http://<server>/Security/login/?BackURL=%252Fadmin%252F

Any ideas on how to fix this issue?


Shawn Parr
Academic Services
Northwestern State

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