Error page rewrites

Since most web servers returns quite crappy error pages and it is often wanted to be able to show a uniform view to the user, trapping error pages in the accelerator and replace the error message with a custom one is very handy.

This is done by detecting HTTP error codes (and Squid error codes) and when detected, request a new error message body from a external URL.

Example:

error_map http://your.web.server/error/404.html 404

This causes 404 errors to be trapped, and the error message from http://your.web.server/error/404.html to be displayed rather than the original error message from the server.

The request sent for the error message is a GET request with the following special HTTP headers:

X-Error-Status:

The received HTTP status code

X-Request-URI

The requested URI

In addition the following client headers are forwarded:

• User-Agent
• Cookie
• X-Forwarded-For
• Via
• Authorization
• Accept
• Referer

And the following server headers:

• Server
• Via
• Location
• Content-Location

The reply send to the client has the HTTP headers of the original error message (except for Content-Length), and a reply body from the specified URL.