How to avoid loops in the exceptions of generic regex rules? - apache

Question

Need to use flags? RewriteCond? The mod_rewrite is enabled and wroking, my problem is how to express my needs: there are a generic rule and some exceptions to the rule, the exceptions not working, and solution must avoid loops.
My /var/www before to use mod_rewrite, was working with usual folders like /var/www/wiki, /var/www/foo, /var/www/bar (each with its index). I need to preserve this behaviour.
Now, with mod_rewrite, I am using a /var/www/index.php to redirect some special strings, that match ^([a-z0-9]+), such as http://myDomain/foo123 or http://myDomain/wiikii. But it matches also "wiki" and "foo", that need exception handling.
My /var/www/.htaccess is
RewriteEngine on
RewriteRule ^/?(foo|bar)([0-9]+) index.php?$1=$2
RewriteRule ^/?([a-z0-9]+) index.php?foobar=$1
so, something like http://myDomain/wiki is redirect to index.php?foobar=wiki, but I need it with no redirection, need Apache going to /wiki.
PS: I try some variations, and some changes into index.php (working with redirections internally), but need elegant and secure Apache Rewrite solution, avoiding loops.

Answer 1

Usually conditions are the way to go, checking against REQUEST_URI.
RewriteCond %{REQUEST_URI} !^/(wiki|foo)$ <-- added
RewriteRule ^([a-z0-9]+)$ index.php?foobar=$1 [L]
An alternative is using e.g. negative lookahead in your regex. For example:
RewriteRule ^(?!(?:foo|wiki)$)([a-z0-9]+) ...
But I find any of the zero width assertions are quite complicated/fragile/unintuitive even if normal regexes come quite easy to you.
?! is negative lookahead
?: is just non-capturing parens for the "or"
The most confusing part about these is that pcre tries hard to find a way to NOT satisfy the negative lookahead, in other words it tries hard to have a succesful overall match.

Answer 2

If you don't want any redirection for wiki folder (and others), you can add a condition
RewriteEngine on
# If requested url is an existing file or folder, don't touch it
RewriteCond %{REQUEST_FILENAME} -d [OR]
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule . - [L]
# If we reach here, this means it's not a file or folder, we can rewrite...
RewriteRule ^(foo|bar)([0-9]+)$ index.php?$1=$2 [L]
RewriteRule ^([a-z0-9]+)$ index.php?foobar=$1 [L]
Also, you can use sort of exception instead, if you don't want it to be apply on all folders/files
RewriteEngine on
# If requested url is a folder/file in exception list, don't touch it
RewriteCond %{REQUEST_URI} ^/(foo|bar|example_file\.html|wiki)$
RewriteRule . - [L]
# If we reach here, this means it's not a file or folder in exception list, we can rewrite...
RewriteRule ^(foo|bar)([0-9]+)$ index.php?$1=$2 [L]
RewriteRule ^([a-z0-9]+)$ index.php?foobar=$1 [L]