Apache rewrite parses URL twice unexpectedly

Question

I'm trying to redirect all the webpages from certain domain names to a specific web application that handles several sites. I have my web app in a folder "skylight2" and another folder, named "testsite", with only a .htaccess file:

RewriteEngine on
RewriteRule ^(((?!skylight2).)*)$ /home/stefano/webroot_aliases/skylight2/$1/?site=testsite [QSA]

I'm using virtual roots, and my httpd-vroot.conf looks like this:

<VirtualHost *:80>
        ServerName webserver
        ServerAlias *.webserver

        UseCanonicalName Off
        VirtualDocumentRoot /home/stefano/webroot_aliases/%1

        Options -Indexes FollowSymLinks -MultiViews
        RewriteLog "/var/log/httpd/vroot_rewrite.log"
        RewriteLogLevel 3

        <Directory /home/stefano/webroot_aliases/>
                Order allow,deny
                Allow from all
                AllowOverride FileInfo Indexes Limit Options

                RewriteEngine On
                RewriteBase / 
        </Directory>
</VirtualHost>

If I try to access testsite.webserver, I get an "object not found" error. This is my rewrite log:

127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#253f320/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_aliases/testsite/articles -> /home/stefano/webroot_aliases/testsite/articles/view
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#253f320/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/articles/view -> articles/view
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#253f320/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(((?!skylight2).)*)$' to uri 'articles/view'
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#253f320/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] rewrite 'articles/view' -> '/home/stefano/webroot_aliases/skylight2/articles/view/?site=testsite'
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#253f320/initial] (3) split uri=/home/stefano/webroot_aliases/skylight2/articles/view/?site=testsite -> uri=/home/stefano/webroot_aliases/skylight2/articles/view/, args=site=testsite
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#253f320/initial] (1) [perdir /home/stefano/webroot_aliases/testsite/] internal redirect with /home/stefano/webroot_aliases/skylight2/articles/view/ [INTERNAL REDIRECT]
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2531a18/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_aliases/testsite/home -> /home/stefano/webroot_aliases/testsite/home/stefano/webroot_aliases/skylight2/articles/view/
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2531a18/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/home/stefano/webroot_aliases/skylight2/articles/view/ -> home/stefano/webroot_aliases/skylight2/articles/view/
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2531a18/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(((?!skylight2).)*)$' to uri 'home/stefano/webroot_aliases/skylight2/articles/view/'
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2531a18/initial/redir#1] (1) [perdir /home/stefano/webroot_aliases/testsite/] pass through /home/stefano/webroot_aliases/testsite/home
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#252f2a0/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/favicon.ico -> favicon.ico
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#252f2a0/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(((?!skylight2).)*)$' to uri 'favicon.ico'
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#252f2a0/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] rewrite 'favicon.ico' -> '/home/stefano/webroot_aliases/skylight2/favicon.ico/?site=testsite'
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#252f2a0/initial] (3) split uri=/home/stefano/webroot_aliases/skylight2/favicon.ico/?site=testsite -> uri=/home/stefano/webroot_aliases/skylight2/favicon.ico/, args=site=testsite
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#252f2a0/initial] (1) [perdir /home/stefano/webroot_aliases/testsite/] internal redirect with /home/stefano/webroot_aliases/skylight2/favicon.ico/ [INTERNAL REDIRECT]
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2533830/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_aliases/testsite/home -> /home/stefano/webroot_aliases/testsite/home/stefano/webroot_aliases/skylight2/favicon.ico/
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2533830/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/home/stefano/webroot_aliases/skylight2/favicon.ico/ -> home/stefano/webroot_aliases/skylight2/favicon.ico/
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2533830/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(((?!skylight2).)*)$' to uri 'home/stefano/webroot_aliases/skylight2/favicon.ico/'
127.0.0.1 - - [08/Mar/2012:07:56:23 --0600] [testsite.webserver/sid#21f2ca0][rid#2533830/initial/redir#1] (1) [perdir /home/stefano/webroot_aliases/testsite/] pass through /home/stefano/webroot_aliases/testsite/home

Apparently, the URL is parsed once (correctly), and then the second time where it's added the prefix again, resulting in an error. Unfortunately, I cannot put a [L] flag to this rule because the URL gets parsed further in the application folder. Can anybody explain to me what is happening?

Thanks

gm

EDIT: I applied the rule:

RewriteRule ^(?!skylight2)(.*)$ skylight2/$1/?site=testsite [QSA,L]

And get this:

127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_a
liases/testsite/articles -> /home/stefano/webroot_aliases/testsite/articles/view
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_al
iases/testsite/articles/view -> articles/view
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(?!skylight2)(.*)$' to uri 
'articles/view'
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] rewrite 'articles/view' -> 'skylight2/articles
/view/?site=testsite'
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (3) split uri=skylight2/articles/view/?site=testsite -> uri=skylight2/articles/view/, args=site=tes
tsite
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] add per-dir prefix: skylight2/articles/view/ -
> /home/stefano/webroot_aliases/testsite/skylight2/articles/view/
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#1951280/initial] (1) [perdir /home/stefano/webroot_aliases/testsite/] internal redirect with /home/stefano/webroot_a
liases/testsite/skylight2/articles/view/ [INTERNAL REDIRECT]
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/w
ebroot_aliases/testsite/home -> /home/stefano/webroot_aliases/testsite/home/stefano/webroot_aliases/testsite/skylight2/articles/view/
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/we
broot_aliases/testsite/home/stefano/webroot_aliases/testsite/skylight2/articles/view/ -> home/stefano/webroot_aliases/testsite/skylight2/articles/view/
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(?!skylight2)(.*)$'
 to uri 'home/stefano/webroot_aliases/testsite/skylight2/articles/view/'
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (2) [perdir /home/stefano/webroot_aliases/testsite/] rewrite 'home/stefano/webroot_aliases/
testsite/skylight2/articles/view/' -> 'skylight2/home/stefano/webroot_aliases/testsite/skylight2/articles/view//?site=testsite'
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (3) split uri=skylight2/home/stefano/webroot_aliases/testsite/skylight2/articles/view//?sit
e=testsite -> uri=skylight2/home/stefano/webroot_aliases/testsite/skylight2/articles/view//, args=site=testsite&site=testsite
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] add per-dir prefix: skylight2/home/ste
fano/webroot_aliases/testsite/skylight2/articles/view// -> /home/stefano/webroot_aliases/testsite/skylight2/home/stefano/webroot_aliases/testsite/skylight2/articles/view//
127.0.0.1 - - [09/Mar/2012:07:22:45 --0600] [testsite.webserver/sid#161fca0][rid#195c9e0/initial/redir#1] (1) [perdir /home/stefano/webroot_aliases/testsite/] internal redirect with /home/stefano/w
ebroot_aliases/testsite/skylight2/home/stefano/webroot_aliases/testsite/skylight2/articles/view// [INTERNAL REDIRECT]

And so on in an infinite loop.

Why does apache keep adding the path info? Neither L nor DPI flags work.

EDIT #2

Following TerryE's advice I used this config:

RewriteEngine On
RewriteBase /testsite
RewriteRule ^(?!skylight2)(.*)$ /skylight2/$1?site=testsite [QSA,L]

And got this:

127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_aliases/testsite/articles -> /home/stefano/webroot_aliases/testsite/articles/view
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/articles/view -> articles/view
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(?!skylight2)(.*)$' to uri 'articles/view'
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] rewrite 'articles/view' -> '/skylight2/articles/view?site=testsite'
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (3) split uri=/skylight2/articles/view?site=testsite -> uri=/skylight2/articles/view, args=site=testsite
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] trying to replace prefix /home/stefano/webroot_aliases/testsite/ with /testsite
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#2d6a740/initial] (1) [perdir /home/stefano/webroot_aliases/testsite/] internal redirect with /skylight2/articles/view [INTERNAL REDIRECT]
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a9968/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_aliases/testsite/skylight2 -> /home/stefano/webroot_aliases/testsite/skylight2/articles/view
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a9968/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/skylight2/articles/view -> skylight2/articles/view
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a9968/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(?!skylight2)(.*)$' to uri 'skylight2/articles/view'
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a9968/initial/redir#1] (1) [perdir /home/stefano/webroot_aliases/testsite/] pass through /home/stefano/webroot_aliases/testsite/skylight2
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18b1290/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/favicon.ico -> favicon.ico
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18b1290/initial] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(?!skylight2)(.*)$' to uri 'favicon.ico'
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18b1290/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] rewrite 'favicon.ico' -> '/skylight2/favicon.ico?site=testsite'
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18b1290/initial] (3) split uri=/skylight2/favicon.ico?site=testsite -> uri=/skylight2/favicon.ico, args=site=testsite
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18b1290/initial] (2) [perdir /home/stefano/webroot_aliases/testsite/] trying to replace prefix /home/stefano/webroot_aliases/testsite/ with /testsite
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18b1290/initial] (1) [perdir /home/stefano/webroot_aliases/testsite/] internal redirect with /skylight2/favicon.ico [INTERNAL REDIRECT]
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a96f0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] add path info postfix: /home/stefano/webroot_aliases/testsite/skylight2 -> /home/stefano/webroot_aliases/testsite/skylight2/favicon.ico
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a96f0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] strip per-dir prefix: /home/stefano/webroot_aliases/testsite/skylight2/favicon.ico -> skylight2/favicon.ico
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a96f0/initial/redir#1] (3) [perdir /home/stefano/webroot_aliases/testsite/] applying pattern '^(?!skylight2)(.*)$' to uri 'skylight2/favicon.ico'
127.0.0.1 - - [10/Mar/2012:08:16:58 --0600] [testsite.webserver/sid#1575ca0][rid#18a96f0/initial/redir#1] (1) [perdir /home/stefano/webroot_aliases/testsite/] pass through /home/stefano/webroot_aliases/testsite/skylight2

Apache throws a "File does not exist: /home/stefano/webroot_aliases/testsite/skylight2" error. The correct URL should be instead /home/stefano/webroot_aliases/skylight2/articles/view.

Could it be because the VirtualDocumentRoot is set to testsite and I can't get out of it once it's set?

By the way, I'm using Apache 2.2.22.

EDIT #3

I actually solved it by placing a symlink "skylight2" in testsite, pointing to "../skylight2". thanks for the help!!

Answer 1

I've come across this bug before and there was an old bugrep on it which fizzled out. It can occur if you do a fall-through on a Per Directory context. But since the rewrite engine loops over the htaccess files anyway, the [L] doesn't mean last it really means "restart loop".

Next your rewrite rule is wrong since your document root is home/stefano/webroot_aliases and rule targets are in URI space not file space so your target should just be skylight2/$1/?site=testsite.

Next the Negative lookahead assertion should not be inside the (.*) loop, so try:

RewriteRule ^(?!skylight2)(.*)$ skylight2/$1/?site=testsite [QSA,L]

If this doesn't work, then append the new rewrite.log extract. Thanks.

Update following comments

The rewrite log shows a DOCROOT of /home/stefano/webroot_aliases/testsite and redirects

articles/view -> testsite/skylight2/articles/view/?site=testsite

Which fails the negative lookahead and loops again, so this is a case when you do need the leading / on the replacement string:

RewriteBase  /testsite
RewriteRule ^(?!skylight2)(.*)$ /skylight2/$1/?site=testsite [QSA,L]