Subversion-Projekte lars-tiefland.prado

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<h1 id="5501">Authentication and Authorization</h1>

<p id="720549" class="block-content">

Authentication is a process of verifying whether someone is who he claims he is. It usually involves a username and a password, but may include any other methods of demonstrating identity, such as a smart card, fingerprints, etc.

</p>

<p id="720550" class="block-content">

Authorization is finding out if the person, once identified, is permitted to manipulate specific resources. This is usually determined by finding out if that person is of a particular role that has access to the resources.

</p>

<h2 id="5502">How PRADO Auth Framework Works</h2>

<p id="720551" class="block-content">

PRADO provides an extensible authentication/authorization framework. As described in <a href="?page=Fundamentals.Applications">application lifecycles</a>, <tt>TApplication</tt> reserves several lifecycles for modules responsible for authentication and authorization. PRADO provides the <tt>TAuthManager</tt> module for such purposes. Developers can plug in their own auth modules easily. <tt>TAuthManager</tt> is designed to be used together with <tt>TUserManager</tt> module, which implements a read-only user database.

</p>

<p id="720552" class="block-content">

When a page request occurs, <tt>TAuthManager</tt> will try to restore user information from session. If no user information is found, the user is considered as an anonymous or guest user. To facilitate user identity verification, <tt>TAuthManager</tt> provides two commonly used methods: <tt>login()</tt> and <tt>logout()</tt>. A user is logged in (verified) if his username and password entries match a record in the user database managed by <tt>TUserManager</tt>. A user is logged out if his user information is cleared from session and he needs to re-login if he makes new page requests.

</p>

<p id="720553" class="block-content">

During <tt>Authorization</tt> application lifecycle, which occurs after <tt>Authentication</tt> lifecycle, <tt>TAuthManager</tt> will verify if the current user has access to the requested page according to a set of authorization rules. The authorization is role-based, i.e., a user has access to a page if 1) the page explicitly states that the user has access; 2) or the user is of a particular role that has access to the page. If the user does not have access to the page, <tt>TAuthManager</tt> will redirect user browser to the login page which is specified by <tt>LoginPage</tt> property.

</p>

<h2 id="5503">Using PRADO Auth Framework</h2>

<p id="720554" class="block-content">

To enable PRADO auth framework, add the <tt>TAuthManager</tt> module and <tt>TUserManager</tt> module to <a href="?page=Configurations.AppConfig">application configuration</a>,

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<service id="page" class="TPageService">

  <modules>

    <module id="auth" class="System.Security.TAuthManager"

               UserManager="users" LoginPage="UserLogin" />

    <module id="users" class="System.Security.TUserManager"

               PasswordMode="Clear">

      <user name="demo" password="demo" />

      <user name="admin" password="admin" />

    </module>

  </modules>

</service>

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<p id="720555" class="block-content">

In the above, the <tt>UserManager</tt> property of <tt>TAuthManager</tt> is set to the <tt>users</tt> module which is <tt>TUserManager</tt>. Developers may replace it with a different user management module that is derived from <tt>TUserManager</tt>.

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<p id="720556" class="block-content">

Authorization rules for pages are specified in <a href="?page=Configurations.PageConfig">page configurations</a> as follows,

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<authorization>

    <allow pages="PageID1,PageID2"

              users="User1,User2"

              roles="Role1" />

    <deny pages="PageID1,PageID2"

              users="?"

              verb="post" />

</authorization>

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<p id="720557" class="block-content">

An authorization rule can be either an <tt>allow</tt> rule or a <tt>deny</tt> rule. Each rule consists of four optional properties:

</p>

<ul id="u1" class="block-content">

<li><tt>pages</tt> - list of comma-separated page names that this rule applies to. If empty, not set or wildcard '*', this rule will apply to all pages under the current directory and all its subdirectories recursively.</li>

<li><tt>users</tt> - list of comma-separated user names that this rule applies to. If empty, not set or wildcard '*', this rule will apply to all users including anonymous/guest user. A character ? refers to anonymous/guest user. And a character @ refers to authenticated users (available since v3.1).</li>

<li><tt>roles</tt> - list of comma-separated user roles that this rule applies to. If empty, not set or wildcard '*', this rule will apply to all user roles.</li>

<li><tt>verb</tt> - page access method that this rule applies to. It can be either <tt>get</tt> or <tt>post</tt>. If empty, not set or wildcard '*', the rule will apply to both methods.</li>

</ul>

<p id="720558" class="block-content">

When a page request is being processed, a list of authorization rules may be available. However, only the <i>first effective</i> rule <i>matching</i> the current user will render the authorization result.

</p>

<ul id="u2" class="block-content">

<li>Rules are ordered bottom-up, i.e., the rules contained in the configuration of current page folder go first. Rules in configurations of parent page folders go after.</li>

<li>A rule is effective if the current page is in the listed pages of the rule AND the current user action (<tt>get</tt> or <tt>post</tt>) is in the listed actions.</li>

<li>A rule matching occurs if the current user name is in the listed user names of an <i>effective</i> rule OR if the user's role is in the listed roles of that rule.</li>

<li>If no rule matches, the user is authorized.</li>

</ul>

<p id="720559" class="block-content">

In the above example, anonymous users will be denied from posting to <tt>PageID1</tt> and <tt>PageID2</tt>, while <tt>User1</tt> and <tt>User2</tt> and all users of role <tt>Role1</tt> can access the two pages (in both <tt>get</tt> and <tt>post</tt> methods).

</p>

<com:SinceVersion Version="3.1.1" />

<p class="block-content">

Since version 3.1.1, the <tt>pages</tt> attribute in the authorization rules can take relative page paths with wildcard '*'. For example, <tt>pages="admin.Home"</tt> refers to the <tt>Home</tt> page under the <tt>admin</tt> directory, and <tt>pages="admin.*"</tt> would refer to all pages under the <tt>admin</tt> directory and subdirectories.

</p>

<p class="block-content">

Also introduced in version 3.1.1 are IP rules. They are specified by a new attribute <tt>ips</tt> in authorization rules. The IP rules are used to determine if an authorization rule aplies to an end-user according to his IP address. One can list a few IPs together, separated by comma ','. Wildcard '*' can be used in the rules. For example, <tt>ips="192.168.0.2, 192.168.1.*"</tt> means the rule applies to users whose IP address is 192.168.0.2 or 192.168.1.*. The latter matches any host in the subnet 192.168.1. If the attribute 'ips' is empty, not set or wildcard '*', the corresponding rule will apply to requests coming from any host address.

</p>

<h2 id="5504">Using <tt>TUserManager</tt></h2>

<p id="720560" class="block-content">

As aforementioned, <tt>TUserManager</tt> implements a read-only user database. The user information are specified in either application configuration or an external XML file.

</p>

<p id="720561" class="block-content">

We have seen in the above example that two users are specified in the application configuration. Complete syntax of specifying the user and role information is as follows,

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<user name="demo" password="demo" roles="demo,admin" />

<role name="admin" users="demo,demo2" />

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<p id="720562" class="block-content">

where the <tt>roles</tt> attribute in <tt>user</tt> element is optional. User roles can be specified in either the <tt>user</tt> element or in a separate <tt>role</tt> element.

</p>

<h2 id="5505">Using <tt>TDbUserManager</tt></h2>

<p id="720563" class="block-content">

<tt>TDbUserManager</tt> is introduced in v3.1.0. Its main purpose is to simplify the task of managing user accounts that are stored in a database. It requires developers to write a user class that represents the necessary information for a user account. The user class must extend from <tt>TDbUser</tt>.

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<p id="720564" class="block-content">

To use <tt>TDbUserManager</tt>, configure it in the application configuration like following:

</p>

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<module id="db"

     class="System.Data.TDataSourceConfig" ..../>

<module id="users"

     class="System.Security.TDbUserManager"

     UserClass="Path.To.MyUserClass"

     ConnectionID="db" />

<module id="auth"

     class="System.Security.TAuthManager"

     UserManager="users" LoginPage="Path.To.LoginPage" />

</com:TTextHighlighter>

</p>

<p id="720565" class="block-content">

In the above, <tt>UserClass</tt> specifies what class will be used to create user instance. The class must extend from <tt>TDbUser</tt>. <tt>ConnectionID</tt> refers to the ID of a <tt>TDataSourceConfig</tt> module which specifies how to establish database connection to retrieve user information.

</p>

<p id="720566" class="block-content">

The user class has to implement the two abstract methods in <tt>TDbUser</tt>: <tt>validateUser()</tt> and <tt>createUser()</tt>. Since user account information is stored in a database, the user class may make use of its <tt>DbConnection</tt> property to reach the database.

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<com:SinceVersion Version="3.1.1" />

<p id="720567" class="block-content">

Since 3.1.1, <tt>TAuthManager</tt> provides support to allow remembering login by setting <tt>AllowAutoLogin</tt> to true. Accordingly, <tt>TDbUser</tt> adds two methods to facilitate the implementation of this feature. In particular, two new methods are introduced: <tt>createUserFromCookie()</tt> and <tt>saveUserToCookie()</tt>. Developers should implement these two methods if remembering login is needed. Below is a sample implementation:

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public function createUserFromCookie($cookie)

{

	if(($data=$cookie->Value)!=='')

	{

		$application=Prado::getApplication();

		if(($data=$application->SecurityManager->validateData($data))!==false)

		{

			$data=unserialize($data);

			if(is_array($data) && count($data)===3)

			{

				list($username,$address,$token)=$data;

				$sql='SELECT passcode FROM user WHERE LOWER(username)=:username';

				$command=$this->DbConnection->createCommand($sql);

				$command->bindValue(':username',strtolower($username));

				if($token===$command->queryScalar() && $token!==false && $address=$application->Request->UserHostAddress)

					return $this->createUser($username);

			}

		}

	}

	return null;

}

public function saveUserToCookie($cookie)

{

	$application=Prado::getApplication();

	$username=strtolower($this->Name);

	$address=$application->Request->UserHostAddress;

	$sql='SELECT passcode FROM user WHERE LOWER(username)=:username';

	$command=$this->DbConnection->createCommand($sql);

	$command->bindValue(':username',strtolower($username));

	$token=$command->queryScalar();

	$data=array($username,$address,$token);

	$data=serialize($data);

	$data=$application->SecurityManager->hashData($data);

	$cookie->setValue($data);

}

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<div class="last-modified">$Id: Auth.page 2245 2007-09-26 13:22:02Z xue $</div></com:TContent>