Apache2 - It seems that rewrite condition is not always applied

Question

I would like to redirect to /lost/index.php only when the image file does not exists. When I try it - it seems that it does not work on browser refresh If I invoke it with a file which exists on the server

/images/image1.jpg

it shows me a file (GOOD - the file exists ) but if I refresh the browser it redirects me to /lost/index.php (WHICH IS BAD)

Below my rules

RewriteEngine On
RewriteLog      /var/log/apache2/rewrite.log
RewriteLogLevel 3

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^/images/(.*)$    /lost/index.php?image=$1 [L,R]

Any ideas ?

It is a bad idea to forward image request to html page. When you use image as `` browser expects image and not a text. Redirect to the image with text `Not found` — Cheery, Oct 14 '14 at 00:08
@Cheery It was just an example, I've change it to index.php - let say that I want to generate this missing picture — szydan, Oct 14 '14 at 00:13
Check what your browser sends in request. Rule looks correct and it should not depend on the refresh. Or, at least, look into the rewrite.log — Cheery, Oct 14 '14 at 00:14
My guess would be that your browser cached the redirect at some stage while you were testing, so it is intermittently using the cache to resolve the URL. I've used a similar configuration with no issues. — itsmejodie, Oct 14 '14 at 00:20
It all works fine if I use %{LA-U:REQUEST_FILENAME}. Below is a snippet from doc: If used in per-server context (i.e., before the request is mapped to the filesystem) SCRIPT_FILENAME and REQUEST_FILENAME cannot contain the full local filesystem path since the path is unknown at this stage of processing. Both variables will initially contain the value of REQUEST_URI in that case. In order to obtain the full local filesystem path of the request in per-server context, use an URL-based look-ahead %{LA-U:REQUEST_FILENAME} to determine the final value of REQUEST_FILENAME. — szydan, Oct 14 '14 at 00:36

score 0 · Accepted Answer · answered Oct 14 '14 at 09:16

So I solved it.

If you define your rewrite rules inside element they should look like

<Directory /var/www/local.example.com>

        ...
        RewriteEngine On

        RewriteCond %{REQUEST_FILENAME} !-l
        RewriteCond %{REQUEST_FILENAME} !-d
        RewriteCond %{REQUEST_FILENAME} !-f
        RewriteRule ^images/(.*)$    /lost/index.html?image=$1 [R]
</Directory>

If you define them "globally" outside the (per-server context) they should look like

RewriteEngine On
RewriteCond %{LA-U:REQUEST_FILENAME} !-l
RewriteCond %{LA-U:REQUEST_FILENAME} !-d
RewriteCond %{LA-U:REQUEST_FILENAME} !-f
RewriteRule ^/images/(.*)$    /lost/index.html?image=$1 [R]

This is due the fact that if used in per-server context (i.e., before the request is mapped to the filesystem) SCRIPT_FILENAME and REQUEST_FILENAME cannot contain the full local filesystem path since the path is unknown at this stage of processing. Both variables will initially contain the value of REQUEST_URI in that case. In order to obtain the full local filesystem path of the request in per-server context, use an URL-based look-ahead %{LA-U:REQUEST_FILENAME} to determine the final value of REQUEST_FILENAME.

What is also important - the pattern has to be different in both cases. In second case it has to starts with '/' while in the first one not. This is due the fact that REQUEST_FILENAME contains the '/' at the beginning for the second case but it does NOT for the first one

Apache2 - It seems that rewrite condition is not always applied

1 Answers1