NAME
Catalyst::Authentication::Realm::Adaptor - Adjust parameters of
authentication processes on the fly

VERSION
Version 0.02

SYNOPSIS
The Catalyst::Authentication::Realm::Adaptor allows for modification of
authentication parameters within the catalyst application. It's
basically a filter used to adjust authentication parameters globally
within the application or to adjust user retrieval parameters provided
by the credential in order to be compatible with a different store. It
provides for better control over interaction between credentials and
stores. This is particularly useful when working with external
authentication such as OpenID or OAuth.

__PACKAGE__->config(
'Plugin::Authentication' => {
'default' => {
class => 'Adaptor'
credential => {
class => 'Password',
password_field => 'secret',
password_type => 'hashed',
password_hash_type => 'SHA-1',
},
store => {
class => 'DBIx::Class',
user_class => 'Schema::Person',
},
store_adaptor => {
method => 'merge_hash',
merge_hash => {
status => [ 'temporary', 'active' ]
}
}
},
}
}
);

The above example ensures that no matter how $c->authenticate() is
called within your application, the key 'status' is added to the
authentication hash. This allows you to, among other things, set
parameters that should always be applied to your authentication process
or modify the parameters to better connect a credential and a store that
were not built to work together. In the above example, we are making
sure that the user search is restricted to those with a status of either
'temporary' or 'active.'

This realm works by intercepting the original authentication information
between the time "$c->authenticate($authinfo)" is called and the time
the realm's "$realm->authenticate($c,$authinfo)" method is called,
allowing for the $authinfo parameter to be modified or replaced as your
application requires. It can also operate after the call to the
credential's "authenticate()" method but before the call to the store's
"find_user" method.

If you don't know what the above means, you probably do not need this
module.

CONFIGURATION
The configuration for this module goes within your realm configuration
alongside your credential and store options.

This module can operate in two points during authentication processing.
The first is prior the realm's "authenticate" call (immediately after
the call to "$c->authenticate()".) To operate here, your filter options
should go in a hash under the key "credential_adaptor".

The second point is after the call to credential's "authenticate" method
but immediately before the call to the user store's "find_user" method.
To operate prior to "find_user", your filter options should go in a hash
under the key "store_adaptor".

The filtering options for both points are the same, and both the
"store_adaptor" and "credential_adaptor" can be used simultaneously in a
single realm.

method
There are four ways to configure your filters. You specify which one you
want by setting the "method" configuration option to one of the
following: "merge_hash", "new_hash", "code", or "action". You then
provide the additional information based on which method you have
chosen. The different options are described below.

merge_hash
credential_adaptor => {
method => 'merge_hash',
merge_hash => {
status => [ 'temporary', 'active' ]
}
}

This causes the original authinfo hash to be merged with a hash
provided by the realm configuration under the key "merge_hash"
key. This is a deep merge and in the case of a conflict, the
hash specified by merge_hash takes precedence over what was
passed into the authenticate or find_user call. The method of
merging is described in detail in the "HASH MERGING" section
below.

new_hash
store_adaptor => {
method => 'new_hash',
new_hash => {
username => '+(user)', # this sets username to the value of $originalhash{user}
user_source => 'openid'
}
}

This causes the original authinfo hash to be set aside and
replaced with a new hash provided under the "new_hash" key. The
new hash can grab portions of the original hash. This can be
used to remap the authinfo into a new format. See the "HASH
MERGING" section for information on how to do this.

code
store_adaptor => {
method => 'code',
code => sub {
my ($realmname, $original_authinfo, $hashref_to_config ) = @_;
my $newauthinfo = {};
## do something
return $newauthinfo;
}
}

The "code" method allows for more complex filtering by executing
code provided as a subroutine reference in the "code" key. The
realm name, original auth info and the portion of the config
specific to this filter are passed as arguments to the provided
subroutine. In the above example, it would be the entire
store_adaptor hash. If you were using a code ref in a
credential_adaptor, you'd get the credential_adapter config
instead.

action
credential_adaptor => {
method => 'action',
controller => 'UserProcessing',
action => 'FilterCredentials'
}

The "action" method causes the adaptor to delegate filtering to
a Catalyst action. This is similar to the code ref above, except
that instead of simply calling the routine, the action specified
is called via "<$c-"forward>>. The arguments passed to the
action are the same as the code method as well, namely the realm
name, the original authinfo hash and the config for the adaptor.

HASH MERGING
The hash merging mechanism in Catalyst::Authentication::Realm::Adaptor
is not a simple merge of two hashes. It has some niceties which allow
for both re-mapping of existing keys, and a mechanism for removing keys
from the original hash. When using the 'merge_hash' method above, the
keys from the original hash and the keys for the merge hash are simply
combined with the merge_hash taking precedence in the case of a key
conflict. If there are sub-hashes they are merged as well.

If both the source and merge hash contain an array for a given hash-key,
the values in the merge array are appended to the original array. Note
that hashes within arrays will not be merged, and will instead simply be
copied.

Simple values are left intact, and in the case of a key existing in both
hashes, the value from the merge_hash takes precedence. Note that in the
case of a key conflict where the values are of different types, the
value from the merge_hash will be used and no attempt is made to merge
or otherwise convert them.

Advanced merging
Whether you are using "merge_hash" or "new_hash" as the method, you have
access to the values from the original authinfo hash. In your new or
merged hash, you can use values from anywhere within the original hash.
You do this by setting the value for the key you want to set to a
special string indicating the key path in the original hash. The string
is formatted as follows: "<'+(key1.key2.key3)'"> This will grab the hash
associated with key1, retrieve the hash associated with key2, and
finally obtain the value associated with key3. This is easier to show
than to explain:

my $originalhash = {
user => {
details => {
age => 27,
haircolor => 'black',
favoritenumbers => [ 17, 42, 19 ]
}
}
};

my $newhash = {
# would result in a value of 'black'
haircolor => '+(user.details.haircolor)',

# bestnumber would be 42.
bestnumber => '+(user.details.favoritenumbers.1)'
}

Given the example above, the value for the userage key would be 27,
(obtained via "<'+(user.details.age)'">) and the value for bestnumber
would be 42. Note that you can traverse both hashes and arrays using
this method. This can be quite useful when you need the values that were
passed in, but you need to put them under different keys.

When using the "merge_hash" method, you sometimes may want to remove an
item from the original hash. You can do this by providing a key in your
merge_hash at the same point, but setting it's value to '-()'. This will
remove the key entirely from the resultant hash. This works better than
simply setting the value to undef in some cases.

NOTES and CAVEATS
The authentication system for Catalyst is quite flexible. In most cases
this module is not needed. Evidence of this fact is that the Catalyst
auth system was substantially unchanged for 2+ years prior to this
modules first release. If you are looking at this module, then there is
a good chance your problem would be better solved by adjusting your
credential or store directly.

That said, there are some areas where this module can be particularly
useful. For example, this module allows for global application of
additional arguments to authinfo for a certain realm via your config. It
also allows for preliminary testing of alternate configs before you
adjust every "$c->authenticate()" call within your application.

It is also useful when combined with the various external authentication
modules available, such as OpenID, OAuth or Facebook. These modules
expect to store their user information in the Hash provided by the
Minimal user store. Often, however, you want to store user information
locally in a database or other storage mechanism. Doing this lies
somewhere between difficult and impossible normally. With the Adapter
realm, you can massage the authinfo hash between the credential's
verification and the creation of the local user, and instead use the
information returned to look up a user instead.

Using the external auth mechanisms and the "action" method, you can
actually trigger an action to create a user record on the fly when the
user has authenticated via an external method. These are just some of
the possibilities that Adaptor provides that would otherwise be very
difficult to accomplish, even with Catalyst's flexible authentication
system.

With all of that said, caution is warranted when using this module. It
modifies the behavior of the application in ways that are not obvious
and can therefore lead to extremely hard to track-down bugs. This is
especially true when using the "action" filter method. When a developer
calls "$c->authenticate()" they are not expecting any actions to be
called before it returns.

If you use the "action" method, I strongly recommend that you use it
only as a filter routine and do not do other catalyst dispatch related
activities (such as further forwards, detach's or redirects). Also note
that it is EXTREMELY DANGEROUS to call authentication routines from
within a filter action. It is extremely easy to accidentally create an
infinite recursion bug which can crash your Application. In short -
DON'T DO IT.

AUTHOR
Jay Kuri, "<jayk at cpan.org>"

BUGS
Please report any bugs or feature requests to
"bug-catalyst-authentication-realm-adaptor at rt.cpan.org", or through
the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Catalyst-Authentication-
Realm-Adaptor>. I will be notified, and then you'll automatically be
notified of progress on your bug as I make changes.

SUPPORT
You can find documentation for this module with the perldoc command.

perldoc Catalyst::Authentication::Realm::Adaptor

You can also look for information at:

* Search CPAN

<http://search.cpan.org/dist/Catalyst-Authentication-Realm-Adaptor/>

* Catalyzed.org Wiki

<http://wiki.catalyzed.org/cpan-modules/Catalyst-Authentication-Real
m-Adaptor>

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