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#!rst
============
URL Rewrites
============

-------------------
Module: mod_rewrite
-------------------

.. meta::
  :keywords: lighttpd, rewrite

.. contents:: Table of Contents

Description
===========

internal redirects, url rewrite

Options
=======

url.rewrite-once
  rewrites a set of URLs internally in the webserver BEFORE they are handled.

  e.g. ::

    url.rewrite-once = ( "<regex>" => "<relative-uri>" )

url.rewrite-repeat
  rewrites a set of URLs internally in the webserver BEFORE they are handled

  e.g. ::

    url.rewrite-repeat = ( "<regex>" => "<relative-uri>" )

The difference between these options is that, while url.rewrite-repeat allows for applying multiple (seperately defined) rewrite rules in a row, url.rewrite-once will cause further rewrite rules to be skipped if the expression was matched. As such, url.rewrite-once behaves like Apaches' RewriteRule ... [L]: http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html#rewriterule

The options ``url.rewrite`` and ``url.rewrite-final`` were mapped to ``url.rewrite-once`` 
in 1.3.16.

NOTE: url rewriting does not work within a $HTTP["url"] conditional. [http://forum.lighttpd.net/topic/1092#3028] 

Regular Expressions
===================

* Patterns ("wildcards") are matched against a string
* Special characters (see [http://www.regular-expressions.info/reference.html] for reference):

 * . (full stop) - match any character
 * \* (asterisk) - match zero or more of the previous symbol
 * \+ (plus) - match one or more of the previous symbol
 * ? (question) - match zero or one of the previous symbol
 * \\? (backslash-something) - match special characters
 * ^ (caret) - match the start of a string
 * $ (dollar) - match the end of a string
 * [set] - match any one of the symbols inside the square braces.
 * [^set] - match any symbol that is NOT inside the square braces.
 * (pattern) - grouping, remember what the pattern matched as a special variable 
 * {n,m} - from n to m times matching the previous character (m could be omitted to mean >=n times)
 * (?!expression) - match anything BUT expression at the current position. Example: ``"^(/(?!(favicon.ico$|js/|images/)).*)" => "/fgci/$1"``

* Normal alphanumeric characters are treated as normal

Replacement Patterns
--------------------

If the matched regex contains groups in parentheses, $1..$9 in the replacement refer to the captured text in the 
matching group "$1" meaning the first group, "$2" the second, and so on.

You can also use certain meta-patterns in replacement text (NOTE: these inferred from examples in other modules, but unverified yet.):

* %% => % sign
* %0 => domain name + tld (Top Level Domain, like .com or .net)
* %1 => tld
* %2 => domain name without tld
* %3 => subdomain 1 name
* %4 => subdomain 2 name

Examples
========

The regex is matching the full REQUEST_URI which is supplied by the user including 
query-string.::

  url.rewrite-once = ( "^/id/([0-9]+)$" => "/index.php?id=$1",
                       "^/link/([a-zA-Z]+)" => "/index.php?link=$1" )

  # the following example, is, however just simulating vhost by rewrite
  # * you can never change document-root by mod_rewrite
  # use mod_*host instead to make real mass-vhost

  # request:        http://any.domain.com/url/ 
  # before rewrite: REQUEST_URI="/www/htdocs/url/" 
  # and DOCUMENT_ROOT="/www/htdocs/" %0="any.domain.com" $1="url/" 
  # after rewrite:  REQUEST_URI="/www/htdocs/any.domain.com/url/" 
  # still, you have DOCUMENT_ROOT=/www/htdocs/

  server.document-root = "/www/htdocs/" 
  $HTTP["host"] =~ "^.*\.([^.]+\.com)$" {
    url.rewrite-once = ( "^/(.*)" => "/%0/$1" )
  }

  # please note, that we have two regular expressions: the one which 
  # $HTTP["host"] is been compared with, and the one of the rewrite rule.
  # the numbered subexpressions available to build the relative uri are
  # being prefixed by '%' for subexpressions of the first regular expression 
  # match and by '$' for subexpressions of the second one.
  # in the case, when the rewrite rule is not included in a conditional 
  # block, only the '$' prefixed variables are available.
  # subexpression 0 is the whole matching expression.

With mod_redirect
-----------------

  Rewrite rules always execute before redirect rules. This is true regardless of the order of module loading or the order of rules in the configuration (lighttpd v1.4.13). However, mod_rewrite provides a mechanism to pass URLs through unmangled: specify "$0" as the rule target.

  e.g. ::

    url.rewrite-once = (
        "^/foo"  => "$0",
        "^/(.*)" => "/handler/$1" 
    )

    url.redirect = (
        "^/foo"  => "http://foo.bar/" 
    )

Workaround for "File name too long" on Windows
----------------------------------------------
While running Lighttpd on Windows you may get ``500 Internal Server Error`` if computed filename is longer than 255 symbols.
In error log it will be ``(response.c.537) file not found ... or so:  File name too long /very_looooong_path ->``.
As workaround you can use ``mod_rewrite`` to avoid this error.

  ::

    server.modules += ("mod_rewrite")
    url.rewrite-once = ( ".{250,}" => "/toolong.php" )

If error handler is PHP, ``$_SERVER['REQUEST_URI']`` will contain full URI.

Passing / Matching the Query string (GET variables)
---------------------------------------------------

If you wanna pass the Query String (?foo=bar) to the rewrite destination you have to explicitly match it:

  ::

    url.rewrite-once = (
        "^/news/([^\?]+)(\?(.*))?" => "/news.php?title=$1&$3" 
    )