RewriteCond: Problem with End Of Line Anchor ($)

[localghost]

Hello there,

I have a regex condition which rewrites the URL from an old scriptiong to new one. Here is it:

RewriteEngine on
RewriteCond %{THE_REQUEST} \?showtopic=(100¦99¦96)
RewriteRule index\.php /articles.php?oldid=%1 [R=301,L]

In fact the old database is a forum board which contains some threads which I do not want rewritten. That is why I isolated the ids of the threads that I want to be rewritten with this RewriteCond:

RewriteCond %{THE_REQUEST} \?showtopic=(100¦99¦96)

The problem that I have now is that in the board there is a new topic with id=960 which matches the regular expression in the RewriteCond.

What I tried to do is put and EOL (end of line) anchor - $

RewriteCond %{THE_REQUEST} \?showtopic=(100¦99¦96)$

For my greatest surprise this now does not match any of the ids in the regular expression. The topic with id=96 is not rewritten, nor is id 100 or 99.

I suspect that for some reason the $ might be interpreted as back reference, but I am not sure at all.

Have you ever had such problem? Or is my regex wrong?

Please, help me solve this.

Thank you

[jd01]

The problem is THE_REQUEST compares the entire request EG
GET http://www.yoursite.com/yourfile.php?yourvariable=somestuff HTTP/1.X

So, to solve the problem, you can check for a space followed by HTTP after the last number you would like to match:

RewriteEngine on
RewriteCond %{THE_REQUEST} \?showtopic=(100¦99¦96)\ HTTP/
RewriteRule index\.php /articles.php?oldid=%1 [R=301,L]

I am not sure what your site structure is, but you might gain some efficiency by start/end anchoring your rule EG ^index\.php$ -- If not all page/file requests will be checked for a match anywhere in the request string, where if anchored, they would break after the first letter if the location requested did not start with an i...

Hope this helps.

Justin

[jdMorgan]

localghost,

Welcome to WebmasterWorld!

The problem is that THE_REQUEST for a forum 96 GET request looks like this:

GET /index.php?showtopic=96 HTTP/1.1

THE_REQUEST is the exact request header sent by the browser, including method (GET), URL-path (index.php?showtopic=96), and protocol (HTTP/1.1).

The easiest solution would be to look for the space after showtopic=96. If you might have another parameter after the topic number, then look for an ampersand as well.

This looks for showtopic=96, followed by zero or more groups composed of an ampersand followed by any number of characters not equal to a space, and then followed by a space and "HTTP/":

RewriteCond %{THE_REQUEST} /index\.php\?showtopic=(100¦99¦96)(&[^\ ]+)*\ HTTP/

If you never have another parameter after showtopic=96, then a simplified version will do:

RewriteCond %{THE_REQUEST} /index\.php\?showtopic=(100¦99¦96)\ HTTP/

In either case, your existing RewriteRule is fine. It is safer to include the seemingly-redundant URL-path in both the RewriteCond and the RewriteRule for this type of rewrite. The URL-path in the RewriteRule can match as a result of another rewrite, while the one in RewriteCond will only match if it was actually requested by the client.

Jim

[localghost]

Thanks Justin

I did not realize the %{THE_REQUEST} contains all the HTTP specific words.

And thanks Jim the (&[^\ ]+)*\ HTTP/ helped for some specific cases.

Thank you guys. It was really helpful.