Apache RewriteRule and Skipping Logic

Question

I've pretty much hit a wall here. As far as I can tell, this should work, but it doesn't.

I have a local development address with a wildcard subdomain of *.localhost, and friendly URLs of /[0-9]/somestring. What I am trying to do is have username.localhost/1/page to localhost?pageId=1&username=username. The complication comes in trying to get both the home page at username.localhost as well as the individual pages i.e. username.localhost/1/page to both work.

RewriteRule ^([0-9]+)/[a-zA-Z0-9\-\_\,\.]+$ - [S=1]
RewriteCond %{HTTP_HOST} !^www.* [NC]
RewriteCond %{HTTP_HOST} ^([^\.]+)\.localhost
RewriteRule ^index.php$ index.php?username=%1
RewriteRule ^([0-9]+)/[a-zA-Z0-9\-\_\,\.]+$ index.php?pageId=$1&username=%1

With /1/page pages, the first rule meant to skip matches and skips, but fails to rewrite correctly. However, if I remove the first 2 rules, it'll rewrite /1/page pages just fine.

It's as if it's not skipping, yet if i change it to S=2, it skips both rules. Argh. Any ideas?

Answer 1

From what I can tell, it actually is doing what you expect it to do. Only, after it does that, it has a second go at your rule set, which messes things up. What's happening looks more specifically like this:

• Request to http://username.localhost/1/page is made
• The input 1/page matches the first rule, S=1 is applied
• The input 1/page matches the third rule, URL is rewritten to index.php?pageId=1&username=username
• An internal redirection is performed by mod_rewrite (all good so far, but...)
• mod_rewrite handles the internal redirection, and starts processing the rules again
• The input index.php does not match the first rule, S=1 is not applied
• The input index.php matches the second rule, URL is rewritten to index.php?username=username
• (the internal redirection occurs again, the same rewrite is performed, but mod_rewrite detects the redirection loop and stops processing now)

There are a few different ways to fix this, but I think the easiest one here is to just make sure the file doesn't exist, and then roll the pattern from the last rule into a condition for the previous one:

# Make sure we haven't rewritten to a file yet (the "directory" gets processed
# before DirectoryIndex index.php is applied)
RewriteCond %{REQUEST_FILENAME} !-f
# Check that the input doesn't match the pattern we want handled later
RewriteCond $0           !^([0-9]+)/[a-zA-Z0-9_,.-]+$
RewriteCond %{HTTP_HOST} !^www.* [NC]
RewriteCond %{HTTP_HOST}  ^([^\.]+)\.localhost
RewriteRule ^.*$ index.php?username=%1

RewriteRule ^([0-9]+)/[a-zA-Z0-9_,.-]+$ index.php?pageId=$1&username=%1

Edit: The above version also catches things that don't match your page pattern and acts like they were index.php?username=username, which might not be desired. The following would avoid that, and is a bit more concise anyway:

RewriteCond %{HTTP_HOST} !^www.* [NC]
RewriteCond %{HTTP_HOST}  ^([^\.]+)\.localhost
RewriteRule ^$ index.php?username=%1

RewriteRule ^([0-9]+)/[a-zA-Z0-9_,.-]+$ index.php?pageId=$1&username=%1