++ed by:
JONASS

1 PAUSE user(s)

Toby Inkster

NAME

Plack::Middleware::Auth::WebID - authentication middleware for WebID

SYNOPSIS

  use Plack::Builder;
  
  my $app   = sub { ... };
  my $cache = CHI->new( ... );
  
  sub unauthenticated
  {
    my ($self, $env) = @_;
    return [
      403,
      [ 'Content-Type' => 'text/plain' ],
      [ '403 Forbidden' ],
    ];
  }
  
  builder
  {
    enable "Auth::WebID",
        cache     => $cache,
        on_unauth => \&unauthenticated;
    $app;
  };

DESCRIPTION

Plack::Middleware::Auth::WebID is a WebID handler for Plack.

If authentication is successful, then the handler sets $env->{WEBID} to the user's WebID URI, and sets $env->{WEBID_OBJECT} to a Web::ID object.

CONFIGURATION

cache

This may be set to an object that will act as a cache for Web::ID objects.

Plack::Middleware::Auth::WebID does not care what package you use for your caching needs. CHI, Cache::Cache and Cache should all work. In fact, any package that provides a similar one-argument get and a two-argument set ought to work. Which should you use? Well CHI seems to be best, however it's Moose-based, so usually too slow for CGI applications. Use Cache::Cache for CGI, and CHI otherwise.

You don't need to set a cache at all, but if there's no cache, then reauthentication (which is computationally expensive) happens for every request. Use of a cache with an expiration time of around 15 minutes should significantly speed up the responsiveness of a WebID-secured site. (For forking servers you probably want a cache that is shared between processes, such as a memcached cache.)

on_unauth

Coderef that will be called if authentication is not successful. You can use this to return a "403 Forbidden" page for example, or try an alternative authentication method.

The default coderef used will simply run the application as normal, but setting $env->{WEBID} to the empty string.

webid_class

Name of an alternative class to use for WebID authentication instead of Web::ID. Note that any such class would need to provide a compatible new constructor.

certificate_env_key

The key within $env where Plack::Middleware::Auth::WebID can find a PEM-encoded client SSL certificate.

Apache keeps this information in $env->{'SSL_CLIENT_CERT'}, so it should be no surprise that this setting defaults to 'SSL_CLIENT_CERT'.

no_object_please

Suppresses setting $env->{WEBID_OBJECT}. $env->{WEBID} will still be set as usual.

SERVER SUPPORT

WebID is an authentication system based on the Semantic Web and HTTPS. It relies on client certificates (but not on certification authorities; self-signed certificates are OK).

So for this authentication module to work...

  • You need to be using a server which supports HTTPS.

    Many web PSGI web servers (e.g. HTTP::Server::Simple, Starman, etc) do not support HTTPS natively. In some cases these are used with an HTTPS proxy in front of them.

  • Your HTTPS server needs to request a client certificate from the client.

  • Your HTTPS server needs to expose the client certificate to Plack via $env.

    If you're using an HTTPS proxy in front of a non-HTTPS web server, then you might need to be creative to find a way to forward this information to your backend web server.

  • The client browser needs to have a WebID-compatible certificate installed.

    Nuff said.

Apache2 (mod_perl and CGI)

The SSLVerifyClient directive can be used to tell Apache that you want it to request a certificate from the client.

Apache is able to deposit the certifcate in an environment variable called SSL_CLIENT_CERT. However by default it might not. Check out the SSLOptions directive and enable the ExportCertData option, or if you're using mod_perl try Plack::Middleware::Apache2::ModSSL.

Gepok

Gepok is one of a very small number of PSGI-compatible web servers that supports HTTPS natively. As of 0.19 it does not request client certificates, however there is a fork which provides client certificate support at https://github.com/tobyink/p5-gepok, which will hopefully be merged into the release versions of Gepok at some point in the near future.

This still doesn't give you the certificate in $env though. I'm working on some Plack middleware to do that. It will be released as Plack::Middleware::GepokX::ModSSL in due course.

BUGS

Please report any bugs to http://rt.cpan.org/Dist/Display.html?Queue=Web-ID.

SEE ALSO

Plack, Web::ID, Web::ID::FAQ.

General WebID information: http://webid.info/, http://www.w3.org/wiki/WebID, http://www.w3.org/2005/Incubator/webid/spec/, http://lists.foaf-project.org/mailman/listinfo/foaf-protocols.

Apache mod_ssl: Plack::Middleware::Apache2::ModSSL, Apache2::ModSSL, http://httpd.apache.org/docs/2.0/mod/mod_ssl.html.

AUTHOR

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

This software is copyright (c) 2012 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.