AuthenHook(3pm)

NAME

Apache::AuthenHook - Perl API for Apache 2.1 authentication

SYNOPSIS

PerlLoadModule Apache::AuthenHook

PerlModule My::OtherProvider

<Location /digest>
  Require valid-user
  AuthType Digest
  AuthName realm1

  AuthDigestProvider My::DigestProvider file My::OtherProvider::digest

  AuthUserFile realm1
</Location>

<Location /basic>
  Require valid-user
  AuthType Basic
  AuthName foorealm

  AuthBasicProvider My::OtherProvider::basic file My::BasicProvider

  AuthUserFile realm1
</Location>

DESCRIPTION

Apache::AuthenHook offers access to the 2.1 Apache authentication API
in Perl. This is different than the authentication API from Apache 1.3 or even Apache 2.0, but in its differences lies strength.

For a full description of how authentication works in 2.1, see

http://www.serverwatch.com/tutorials/article.php/2202671

Basically, the difference between 2.0 and 2.1 is that authentication is now delegated to providers, and each provider has a specific purpose.
For instance, mod_authn_file covers gleaning the password from an
.htpasswd or .htdigest file, while mod_auth_basic covers the Basic
dialogue between the client and server, regardless of the source of the password. The best part of all this (to me) is that Digest
authentication is also delegated out - mod_auth_digest now handles all the intricacies of Digest authentication (including the elusive MSIE
support) which means you don't need to worry about them (and neither do I). All that Digest authentication requires is *some* authentication
provider to provide user credentials - this can be via mod_authn_file
or another mechanism of your choosing.

Apache::AuthenHook registers and coordinates the use of Perl handlers
as authentication providers.

How does this affect you? Read on...

EXAMPLE

Say you want to enable Digest authentication in your Apache 2.1 server...: PerlLoadModule Apache::AuthenHook; <Location /digest>
Require valid-user
AuthType Digest
AuthName realm1

AuthDigestProvider My::DigestProvider file

AuthUserFile realm1; </Location>
This configuration means that My::DigestProvider will be responsible for providing user credentials for requests to /digest. if My::DigestProvider finds a suitable user, mod_auth_digest will verify those credentials and take care of setting all the proper headers, set the proper HTTP response status, and so on. If My::DigestProvider cannot find a matching user it can decide what to do next - either pass the user to the next provider (in this case the default file provider, which will use the flat file "realm1") or decide that no user means no access.
Here is a simple My::DigestProvider: use Apache2::Const -compile => qw(OK DECLINED HTTP_UNAUTHORIZED);; sub handler {

my ($r, $user, $realm, $hash) = @_;

# user1 at realm1 is found - pass to mod_auth_digest
if ($user eq 'user1' && $realm eq 'realm1') {
$$hash = 'eee52b97527306e9e8c4613b7fa800eb';
return Apache2::Const::OK;

}

# user2 is denied outright
if ($user eq 'user2' && $realm eq 'realm1') {

return Apache2::Const::HTTP_UNAUTHORIZED;

}

# all others are passed along to the next provider
return Apache2::Const::DECLINED;; }
isn't that easy?
the only thing that is a bit tricky here is $$hash. the fourth argument passed to your handler, $hash, is a reference to to a simple scalar that needs to be populated with the MD5 hash of the user:realm:password combination you determine for the incoming user. this may seem a bit strange, but it is actually exactly how things work over in Apache C land, so I guess that makes it ok.
as you can see, returning OK means "user found" and requires that $$hash be populated - mod_auth_digest will take care of determining whether the hash matches the incoming Digest criteria. returning HTTP_UNAUTHORIZED (which is the same as the former and still available AUTH_REQUIRED constant) means "no access." returning DECLINED means "some other provider can try."
The steps are remarkably similar for Basic authentication, first: <Location /basic>
Require valid-user
AuthType Basic
AuthName foorealm

AuthBasicProvider My::BasicProvider file

AuthUserFile realm1; </Location>
then: use Apache2::Const -compile => qw(OK DECLINED HTTP_UNAUTHORIZED);; sub handler {

my ($r, $user, $password) = @_;

# user1/basic1 is ok
if ($user eq 'user1' && $password eq 'basic1') {
return Apache2::Const::OK;

}

# user2 is denied outright
if ($user eq 'user2') {

return Apache2::Const::HTTP_UNAUTHORIZED;

}

# all others are passed along to the next provider
return Apache2::Const::DECLINED;; }
In the case of Basic authentication, the return codes mean essentially the same thing. The one exception is that OK means that you have checked the user against the password and have found that they match (as opposed to with Digest, where the actual verification is not done by you).
These explanations should be enough to get you going - see the files in the test suite for more examples.

NOTES

This has been tested under the prefork MPM only, using mostly Perl
5.9.0 (as well as some 5.8.0). It will not work under threaded MPMs soon, just not yet.

FEATURES/BUGS

This is very much so alphaware, so beware - bugs may lurk in unexpected places. there is one bug that is outside of my control, though, and
concerns MSIE and Digest authentication for URIs that include query
strings. see

http://httpd.apache.org/docs-2.0/mod/mod_auth_digest.html

one workaround for this issue is is to use POST instead of GET for your forms.

A limitation of this interface is that you can't use Perl providers
that are not at least two levels deep - the criterion for registering a Perl provider is a simple check for a double-colon. for example,
My::Provider will work while Provider won't (although Provider::handler will). anyway, single level handlers are rare, so fixing it would be a lot of trouble for little benefit.

AUTHOR

Geoffrey Young <geoff@modperlcookbook.org>

COPYRIGHT

This module is free software. It may be used, redistributed and/or
modified under the same terms as Perl itself.

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