Writing rules and headers
=========================

LL::NG manages applications by their hostname (Apache Virtual Hosts or
Nginx Block Servers). Rules are used for protecting applications,
and HTTP headers are appended to each request for sending data to protected
applications (for logs, profiles,...).


.. attention::

    Note that variables designed by $xx correspond to the
    name of the :doc:`exported variables<exportedvars>` or
    :ref:`macro names<macros_and_groups>` except for ``$ENV{<cgi-header>}`` which
    correspond to CGI headers (``$ENV{REMOTE_ADDR}`` for example).

Available $ENV variables
------------------------

The %ENV hash provides:

-  all headers in CGI format (``User-Agent`` becomes
   ``HTTP_USER_AGENT``)
-  some CGI variables depending on the context:

   -  For portal: all CGI standard variables (you can add custom
      headers using ``fastcgi_param`` with Nginx),
   -  For Apache handler: REMOTE_ADDR, QUERY_STRING, REQUEST_URI,
      SERVER_PORT, REQUEST_METHOD,
   -  For Nginx handler: all variables given by ``fastcgi_param``
      commands.

-  For Portal:

   -  $ENV{urldc} : Origin URL before Handler redirection, in cleartext
   -  $ENV{_url} : Origin URL before Handler redirection, base64 encoded

See also :doc:`extended functions<extendedfunctions>`.

.. tip::

    You can use %ENV hash or $env hash ref. Both syntaxes are available
    for compatibity. 

    ::

       $ENV{REMOTE_ADDR} and $env->{REMOTE_ADDR} are similar.

.. _rules:

Rules
-----

A rule associates a `regular
expression <http://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expressions>`__
to a Perl boolean expression or a keyword.

|image0|

Examples:

=============================================================================================================================================== ================== ======================================
Goal                                                                                                                                            Regular expression Rule
=============================================================================================================================================== ================== ======================================
Restrict /admin/ directory to user bart.simpson                                                                                                 ^/admin/
Restrict /js/ and /css/ directory to authenticated users                                                                                        ^/(css|js)/        accept
Deny access to /config/ directory                                                                                                               ^/config/          deny
Do not restrict /public/                                                                                                                        ^/public/          skip
Do not restrict /skip/ and restrict other to authenticated users                                                                                ^/skip/            $ENV{REQUEST_URI} =~ /skip/ ? skip : 1
Makes authentication optional, but authenticated users are seen as such (that is, user data are sent to the app through HTTP headers)           ^/forum/           unprotect
Restrict access to the whole site to users that have the LDAP description field set to "LDAP administrator" (must be set in exported variables) default
=============================================================================================================================================== ================== ======================================

The "**default**" access rule is used if none rule matches the
current URL.


.. tip::

    See :doc:`the rule examples page<rules_examples>` for few
    common use cases


.. tip::


    -  Comments can be employed for ordering your rules: rules are applied depending on
       comment alphabetical order (or regexp if no comment is defined). See
       :ref:`security chapter<security-write-good-rules>` to learn more
       about rules best practice.
    -  See :ref:`performances<performances-handler-performance>` to learn how
       using macros and groups in rules.


Rules can also be used for intercepting logout URL:

================================================================================================================= ======================= =====================================
Goal                                                                                                              Regular expression      Rule
================================================================================================================= ======================= =====================================
Logout user from Lemonldap::NG and redirect it to http://intranet/                                                ``^/index.php\?logout`` logout_sso http://intranet/
Logout user from current application and redirect it to the menu **(Apache only)**                                ``^/index.php\?logout`` logout_app https://auth.example.com/
Logout user from current application and from Lemonldap::NG and redirect it to http://intranet/ **(Apache only)** ``^/index.php\?logout`` logout_app_sso http://intranet/
================================================================================================================= ======================= =====================================


.. danger::

    \ For ``logout_app`` and ``logout_app_sso`` rules to work with Nginx, you need
    lua module, and you must enable ``nginx-lua-headers.conf``.
    Also, make sure the ``header_filter_by_lua`` and corresponding ``error_page`` directives
    are present in the appropriate "location" section. See ``test-nginx.conf`` for more information.

By default, users will be redirected to the Portal if no URL is defined,
or to the specified URL if exists.


.. attention::

    Only current application is concerned by logout_app\*
    targets. Be careful with some applications which does not check
    headers sent by LL::NG after having created their own application cookies.
    If so, you can redirect users to a HTML page that explain that it is better
    to close browser after logout.

Rules based on authentication level
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

LL::NG set an "authentication level" during authentication process. This
level depends on authentication backend used by this user. Default
values are:

-  0 for :doc:`Null<authnull>`
-  1 for :doc:`CAS<authcas>`, :doc:`OpenID Connect<authopenidconnect>`,
   :doc:`Facebook<authfacebook>`,…
-  2 for web-form based authentication (:doc:`LDAP<authldap>`,
   :doc:`DBI<authdbi>`,…)
-  3 for :doc:`Kerberos<authkerberos>`
-  5 for :doc:`SSL<authssl>`

There are three ways to impose users a higher authentication level:

-  writing a rule based on authentication level:
   ``$authenticationLevel > 3``
-  since 2.0, set a minimum level in virtual host options (default value
   for ALL access rules)
-  since 2.0.7, a minimum authentication level can be set for each URI
   access rule. Useful if URI are protected by different types of
   handler (AuthBasic -> level 2, Main -> level set by authentication
   backend).


.. tip::

    Instead of returning a 403 code, "minimum level" returns users
    to a form that explains that a higher level is required and propose to
    reauthenticate himself.

.. _headers:

Headers
-------

Headers are associations between an header name and a perl expression
that returns a value. Headers are used for sending user data to protected
applications.

Examples:

============================= ============ =======================
Goal                          Header name  Header value
============================= ============ =======================
Give the uid (for accounting) Auth-User    $uid
Give a static value           Some-Thing   "static-value"
Give display name             Display-Name "$givenName $surName"
Give a non ASCII data         Display-Name
============================= ============ =======================

As described in
:ref:`performances chapter<performances-handler-performance>`, you can
use macros, local macros,...


.. attention::

    -  Since many HTTP servers refuse non ASCII headers, it is recommended
       to use encode_base64() function to transmit those headers
    -  Do not forget to add an empty string as second argument to
       encode_base64 function to avoid a "newline" characters insertion in
       result: ``encode_base64($string, '')``
    -  Header names must contain only letters and "-" character.
       With Nginx, you can bypass this restriction by using
       ``underscores_in_headers on;`` directive




.. tip::

    By default, SSO cookie is hidden. So protected applications
    cannot retrieve SSO session key. But you can forward this key if
    absolutely needed (NOT recommanded because can be a security issue):

    ::

       Session-ID => $_session_id



Available functions
-------------------

In addition to macros and name, you can use some functions in rules and
headers:

-  :doc:`LL::NG extended functions<extendedfunctions>`
-  :doc:`Your custom functions<customfunctions>`

Wildcards in hostnames
----------------------

|image1| Since 2.0, a wildcard can be used in virtualhost name (not in
aliases !): ``*.example.com`` matches all hostnames that belong to
``example.com`` domain. Version 2.0.9 improves this and allows better
wildcards such as ``test-*.example.com`` or ``test-%.example.com``. The
``%`` wilcard doesn't match subdomains.

Even if a wildcard exists, if a VirtualHost is explicitly declared, this
rule will be applied. Example with precedence order for test.sub.example.com:

#. test.sub.example.com
#. test%.sub.example.com
#. test*.sub.example.com
#. %.sub.example.com
#. \*.sub.example.com
#. \*.example.com (``%.example.com`` does not match
   test.sub.example.com)

.. |image0| image:: /documentation/manager-rule.png
   :class: align-center
.. |image1| image:: /documentation/new.png
   :width: 35px
