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CGI::Application::PlugCGI::Application::Plugin::Authentication::Driver::DBI(3)

NAME
       CGI::Application::Plugin::Authentication::Driver::DBI - DBI
       Authentication driver

VERSION
       This document describes
       CGI::Application::Plugin::Authentication::Driver::DBI version 0.20

SYNOPSIS
	use base qw(CGI::Application);
	use CGI::Application::Plugin::Authentication;

	__PACKAGE__->authen->config(
	    DRIVER => [ 'DBI',
		DBH	    => $self->dbh,
		TABLE	    => 'user',
		CONSTRAINTS => {
		    'user.name'		=> '__CREDENTIAL_1__',
		    'MD5:user.password' => '__CREDENTIAL_2__'
		},
	    ],
	);

DESCRIPTION
       This Authentication driver uses the DBI module to allow you to
       authenticate against any database for which there is a DBD module.  You
       can either provide an active database handle, or provide the parameters
       necessary to connect to the database.

       When describing the database structure, you need to specify some or all
       of the following parameters: TABLE(S), JOIN_ON, COLUMNS, CONSTRAINTS,
       ORDER_BY and LIMIT.

   DBH
       The DBI database handle to use. Defaults to "$self-"dbh()>, which is
       provided and configured through CGI::Application::Plugin::DBH

   TABLE(S)  (required)
       Provide either a single table name, or an array of table names.	You
       can give the table names aliases which can be referenced in later
       columns.

	    TABLE => 'users',

	- or -

	    TABLES => ['users U', 'domains D'],

   JOIN_ON  (conditionally required)
       If you have specified multiple tables, then you need to provide an SQL
       expression that can be used to join those tables.

	    JOIN_ON => 'user.domainid = domain.id',

	- or -

	    JOIN_ON => 'U.domainid = D.id',

   COLUMNS  (optional)
       This is a hash of columns/values that should be pulled out of the
       database and validated locally in perl.	Most credentials can be
       checked right in the database (example username = ?), but some
       parameters may need to be tested locally in perl, so they must be
       listed in the COLUMNS option.  One example of a value that needs to be
       tested in perl is a crypted password.  In order to test a crypted
       password, you need to take the entered password, and crypt it with the
       salt of the already crypted password.  But until we actually see the
       password that is in the database, we will not know the value of the
       salt that was used to encrypt the password.  So we pull the value out
       using COLUMNS, and the test will be performed automatically in perl.

       Any value that matches __CREDENTIAL_n__ (where n is a number) will be
       replaced with the corresponding credential that was entered by the
       user.  For an explanation of what the credentials are and where they
       come from, see the section headed with CREDENTIALS in
       CGI::Application::Plugin::Authentication.

	    COLUMNS => { 'crypt:password' => '__CREDENTIAL_2__' },

   CONSTRAINTS	(optional)
       You will most likely always have some constraints to use.  These
       constraints will be added to the WHERE clause of the SQL query, and
       will ideally reduce the number of returned rows to one.

       Any value that matches __CREDENTIAL_n__ (where n is a number) will be
       replaced with the corresponding credential that was entered by the
       user.  For an explanation of what the credentials are and where they
       come from, see the section headed with CREDENTIALS in
       CGI::Application::Plugin::Authentication.

	    CONSTRAINTS => {
		'users.email'	       => '__CREDENTIAL_1__',
		'MD5:users.passphrase' => '__CREDENTIAL_2__',
		'users.active'	       => 1,
	    }

   ORDER_BY  (optional)
       This option allows you to order the result set, in case the query
       returns multiple rows.

	    ORDER_BY => 'created DESC'

       Note: This option is only useful if you also specify the COLUMNS
       option.

   LIMIT  (optional)
       In some situations your query may return multiple rows when you only
       want it to return one.  For example if you insert and date a new row
       instead of updating the existing row when the details for an account
       change.	In this case you want the newest record from the result set,
       so it will be important to order the result set and limit it to return
       only one row.

	    LIMIT => 1

       Note: This option is only useful if you also specify the COLUMNS
       option.

ENCODED PASSWORDS
       It is quite common to store passwords in a database in some form that
       makes them hard (or virtually impossible) to guess.  Most of the time
       one way encryption techniques like Unix crypt or MD5 hashes are used to
       store the password securely (I would recommend using MD5 or SHA1 over
       Unix crypt).  If you look at the examples listed above, you can see
       that you can mark your columns with an encoding type.  Here is another
       example:

	   CONSTRAINTS => {
	       username	      => '__CREDENTIAL_1__',
	       'MD5:password' => '__CREDENTIAL_2__',
	   }

       Here the password field is expected to be stored in the database in MD5
       format.	In order for the MD5 check to work for all databases, the
       password will be encoded using perl, and then checked against the value
       in the database.	 So in effect, the following will be done:

	   $username = 'test';
	   $password = '123';
	   $encoded_password = 'ICy5YqxZB1uWSwcVLSNLcA';
	   $sth = $dbh->prepare('SELECT count(*) FROM users WHERE username = ? AND password = ?';
	   $sth->execute($username, $encoded_password);
	   # I we found a row, then the user credentials are valid and the user is logged in

       This is all automatically performed behind the scenes when you specify
       that a certain field in the database is encoded.

       We have to handle this slightly different when working with Unix crypt.
       In order to crypt a password, you need to provide the crypt function
       with a 2 character salt value.  These are usually just generated
       randomly, and when the value is crypted, the first two characters of
       the resulting string will be the 2 salt characters.  The problem comes
       into play when you want to check a password against a crypted password.
       You need to know the salt in order to properly test the password.  But
       in our case, the crypted password is in the DB.	This means we can not
       generate the crypted test password before we run the query against the
       database.

       So instead we pull the value of the crypted password out of the
       database, and then perform the tests after the query, instead of
       before.	Here is an example:

	   CONSTRAINTS => { 'username'	     => '__CREDENTIAL_1__' },
	   COLUMNS     => { 'crypt:password' => '__CREDENTIAL_2__' },

       And here is what will happen behind the scenes:

	   $username = 'test';
	   $password = '123';
	   $sth = $dbh->prepare('SELECT password FROM users WHERE username = ?';
	   $sth->execute($username);
	   ($encoded_password) = $sth->fetchrow_array;
	   if ($encoded_password eq crypt($password, $encoded_password)) {
	       # The credentials are valid and the user is logged in
	   }

       Again, this is all done automatically behind the scenes, but I've
       included it here to illustrate how the queries are performed, and how
       the comparisons are handled.  For more information see the section
       labelled ENCODED PASSWORDS in the
       CGI::Application::Plugin::Authentication::Driver docs.

EXAMPLE
	# using multiple tables
	#  Here we check three credentials (user, password and domain) across
	#  two separate tables.
	__PACKAGE__->authen->config(
	    DRIVER => [ 'DBI',
		# the handle comes from $self->dbh, via the "DBH" plugin.
		TABLES	    => ['user', 'domain'],
		JOIN_ON	    => 'user.domainid = domain.id',
		CONSTRAINTS => {
		    'user.name'	    => '__CREDENTIAL_1__',
		    'user.password' => '__CREDENTIAL_2__',
		    'domain.name'   => '__CREDENTIAL_3__'
		}
	    ],
	);

	 - or -

	# using filtered fields
	#  Here the password column contains values that are encoded using unix crypt
	#  and since we need to know the salt in order to encrypt the password
	#  properly, we need to pull out the password, and check it locally
	__PACKAGE__->authen->config(
	    DRIVER => [ 'DBI',
		DBH	    => $dbh,   # provide your own DBI handle
		TABLE	    => 'user',
		CONSTRAINTS => { 'user.name'	  => '__CREDENTIAL_1__' }
		COLUMNS	    => { 'crypt:password' => '__CREDENTIAL_2__' },
	    ],
	);

	- or -

	# extra constraints
	#  Here we only check users where the 'active' column is true
	__PACKAGE__->authen->config(
	    DRIVER => [ 'DBI',
		TABLE	    => 'user',
		CONSTRAINTS => {
		    'user.name'	    => '__CREDENTIAL_1__',
		    'user.password' => '__CREDENTIAL_2__',
		    'user.active'   => 't'
		},
	    ],
	);

	- or -

	# all of them combined
	#  Here the user is required to enter a username and password (which is
	#  crypted), and a daily code that changes every day (which is encoded using
	#  an MD5 hash hex format and stored in upper case).
	__PACKAGE__->authen->config(
	    DRIVER => [ 'DBI',
		TABLES	    => ['user U', 'dailycode D'],
		JOIN_ON	    => 'U.userid = D.userid',
		CONSTRAINTS => {
		    'U.name'		=> '__CREDENTIAL_1__',
		    'uc:md5_hex:D.code' => '__CREDENTIAL_3__',
		    'D.date'		=> 'now'
		},
		COLUMNS	    => {
		    'crypt:U.password' => '__CREDENTIAL_2__'
		},
	    ],
	);

METHODS
   verify_credentials
       This method will test the provided credentials against the values found
       in the database, according to the Driver configuration.

SEE ALSO
       CGI::Application::Plugin::Authentication::Driver,
       CGI::Application::Plugin::Authentication, perl(1)

LICENCE AND COPYRIGHT
       Copyright (c) 2005, SiteSuite. All rights reserved.

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

DISCLAIMER OF WARRANTY
       BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
       FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
       WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
       PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
       EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
       WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
       ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
       YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
       NECESSARY SERVICING, REPAIR, OR CORRECTION.

       IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
       WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
       REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
       TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
       CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
       SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
       RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
       FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
       SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
       DAMAGES.

perl v5.14.1	      CGI::Application::Plugin::Authentication::Driver::DBI(3)
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