Apache Access Handler Perl Module

Table of Contents

The OpenILS::WWW::AccessHandler Perl module is intended for limiting patron access to configured locations in Apache. These locations could be folder trees, static files, non-Evergreen dynamic content, or other Apache features/modules. It is intended as a more patron-oriented and transparent version of the OpenILS::WWW::Proxy and OpenILS::WWW:Proxy::Authen modules.

Instead of using Basic Authentication the AccessHandler module instead redirects to the OPAC for login. Once logged in additional checks can be performed, based on configured variables:

  • Permission Checks (at Home OU or specified location)

  • Home OU Checks (Org Unit or Descendant)

  • "Good standing" Checks (Not Inactive or Barred)

Use of the module is a simple addition to a Location block in Apache:

<Location /path/to/be/protected>
    PerlAccessHandler OpenILS::WWW::AccessHandler
    # For each option you wish to set:
    PerlSetVar OPTION "VALUE"

The available options are:

  • Default: /eg/opac/login

  • The page to redirect to when Login is needed

  • Default: redirect_to

  • The variable the login page wants the "destination" URL stored in

  • Default: <unset>

  • URL to go to if Permission, Good Standing, or Home OU checks fail. If not set a 403 error is generated instead. To customize the 403 you could use an ErrorDocument statement.

  • Default: <User Home OU>

  • Org Unit to check Permissions at and/or to load Referrer from. Can be a shortname or an ID.

  • Default: <unset>

  • Permission, or comma- or space-delimited set of permissions, the user must have to access the protected area.

  • Default: 0

  • If set to a true value the user must be both Active and not Barred.

  • Default: <unset>

  • An Org Unit, or comma- or space-delimited set of Org Units, that the user’s Home OU must be equal to or a descendant of to access this resource. Can be set to shortnames or IDs.

  • Default: <unset>

  • Library Setting to pull a forced referrer string out of, if set.

As the AccessHandler module does not actually serve the content it is protecting, but instead merely hands control back to Apache when it is done authenticating, you can protect almost anything else you can serve with Apache.

Use Cases

The general use of this module is "protect access to something else" - what that something else is will vary. Some possibilities:

  • Apache features

    • Automatic Directory Indexes

    • Proxies (see below)

      • Electronic Databases

      • Software on other servers/ports

  • Non-Evergreen software

    • Timekeeping software for staff

    • Specialized patron request packages

  • Static files and folders

    • Semi-public Patron resources

    • Staff-only downloads

Proxying Websites

One potentially interesting use of the AccessHandler module is to protect an Apache Proxy configuration. For example, after installing and enabling mod_proxy, mod_proxy_http, and mod_proxy_html you could proxy websites like so:

<Location /proxy/>
    # Base "Rewrite URLs" configuration
    ProxyHTMLLinks  a       href
    ProxyHTMLLinks  area        href
    ProxyHTMLLinks  link        href
    ProxyHTMLLinks  img     src longdesc usemap
    ProxyHTMLLinks  object      classid codebase data usemap
    ProxyHTMLLinks  q       cite
    ProxyHTMLLinks  blockquote  cite
    ProxyHTMLLinks  ins     cite
    ProxyHTMLLinks  del     cite
    ProxyHTMLLinks  form        action
    ProxyHTMLLinks  input       src usemap
    ProxyHTMLLinks  head        profile
    ProxyHTMLLinks  base        href
    ProxyHTMLLinks  script      src for

    # To support scripting events (with ProxyHTMLExtended On)
    ProxyHTMLEvents onclick ondblclick onmousedown onmouseup \
            onmouseover onmousemove onmouseout onkeypress \
            onkeydown onkeyup onfocus onblur onload \
            onunload onsubmit onreset onselect onchange

    # Limit all Proxy connections to authenticated sessions by default
    PerlAccessHandler OpenILS::WWW::AccessHandler

    # Strip out Evergreen cookies before sending to remote server
    RequestHeader edit Cookie "^(.*?)ses=.*?(?:$|;)(.*)$" $1$2
    RequestHeader edit Cookie "^(.*?)eg_loggedin=.*?(?:$|;)(.*)$" $1$2

<Location /proxy/example/>
    # Proxy example.net
    ProxyPass http://www.example.net/
    ProxyPassReverse http://www.example.net/
    ProxyPassReverseCookieDomain example.net example.com
    ProxyPassReverseCookiePath / /proxy/example/

    ProxyHTMLEnable On
    ProxyHTMLURLMap http://www.example.net/ /proxy/example/
    ProxyHTMLURLMap / /proxy/mail/
    ProxyHTMLCharsetOut *

    # Limit to BR1 and BR3 users
    PerlSetVar OILSAccessHandlerHomeOU "BR1,BR3"

As mentioned above, this can be used for multiple reasons. In addition to websites such as online databases for patron use you may wish to proxy software for staff or patron use to make it appear on your catalog domain, or perhaps to keep from needing to open extra ports in a firewall.