consumer.php

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<?php
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/**
 * This module documents the main interface with the OpenID consumer
 * library.  The only part of the library which has to be used and
 * isn't documented in full here is the store required to create an
 * Auth_OpenID_Consumer instance.  More on the abstract store type and
 * concrete implementations of it that are provided in the
 * documentation for the Auth_OpenID_Consumer constructor.
 *
 * OVERVIEW
 *
 * The OpenID identity verification process most commonly uses the
 * following steps, as visible to the user of this library:
 *
 *   1. The user enters their OpenID into a field on the consumer's
 *      site, and hits a login button.
 *   2. The consumer site discovers the user's OpenID server using the
 *      YADIS protocol.
 *   3. The consumer site sends the browser a redirect to the identity
 *      server.  This is the authentication request as described in
 *      the OpenID specification.
 *   4. The identity server's site sends the browser a redirect back
 *      to the consumer site.  This redirect contains the server's
 *      response to the authentication request.
 *
 * The most important part of the flow to note is the consumer's site
 * must handle two separate HTTP requests in order to perform the full
 * identity check.
 *
 * LIBRARY DESIGN
 *
 * This consumer library is designed with that flow in mind.  The goal
 * is to make it as easy as possible to perform the above steps
 * securely.
 *
 * At a high level, there are two important parts in the consumer
 * library.  The first important part is this module, which contains
 * the interface to actually use this library.  The second is the
 * Auth_OpenID_Interface class, which describes the interface to use
 * if you need to create a custom method for storing the state this
 * library needs to maintain between requests.
 *
 * In general, the second part is less important for users of the
 * library to know about, as several implementations are provided
 * which cover a wide variety of situations in which consumers may use
 * the library.
 *
 * This module contains a class, Auth_OpenID_Consumer, with methods
 * corresponding to the actions necessary in each of steps 2, 3, and 4
 * described in the overview.  Use of this library should be as easy
 * as creating an Auth_OpenID_Consumer instance and calling the
 * methods appropriate for the action the site wants to take.
 *
 * STORES AND DUMB MODE
 *
 * OpenID is a protocol that works best when the consumer site is able
 * to store some state.  This is the normal mode of operation for the
 * protocol, and is sometimes referred to as smart mode.  There is
 * also a fallback mode, known as dumb mode, which is available when
 * the consumer site is not able to store state.  This mode should be
 * avoided when possible, as it leaves the implementation more
 * vulnerable to replay attacks.
 *
 * The mode the library works in for normal operation is determined by
 * the store that it is given.  The store is an abstraction that
 * handles the data that the consumer needs to manage between http
 * requests in order to operate efficiently and securely.
 *
 * Several store implementation are provided, and the interface is
 * fully documented so that custom stores can be used as well.  See
 * the documentation for the Auth_OpenID_Consumer class for more
 * information on the interface for stores.  The implementations that
 * are provided allow the consumer site to store the necessary data in
 * several different ways, including several SQL databases and normal
 * files on disk.
 *
 * There is an additional concrete store provided that puts the system
 * in dumb mode.  This is not recommended, as it removes the library's
 * ability to stop replay attacks reliably.  It still uses time-based
 * checking to make replay attacks only possible within a small
 * window, but they remain possible within that window.  This store
 * should only be used if the consumer site has no way to retain data
 * between requests at all.
 *
 * IMMEDIATE MODE
 *
 * In the flow described above, the user may need to confirm to the
 * lidentity server that it's ok to authorize his or her identity.
 * The server may draw pages asking for information from the user
 * before it redirects the browser back to the consumer's site.  This
 * is generally transparent to the consumer site, so it is typically
 * ignored as an implementation detail.
 *
 * There can be times, however, where the consumer site wants to get a
 * response immediately.  When this is the case, the consumer can put
 * the library in immediate mode.  In immediate mode, there is an
 * extra response possible from the server, which is essentially the
 * server reporting that it doesn't have enough information to answer
 * the question yet.  In addition to saying that, the identity server
 * provides a URL to which the user can be sent to provide the needed
 * information and let the server finish handling the original
 * request.
 *
 * USING THIS LIBRARY
 *
 * Integrating this library into an application is usually a
 * relatively straightforward process.  The process should basically
 * follow this plan:
 *
 * Add an OpenID login field somewhere on your site.  When an OpenID
 * is entered in that field and the form is submitted, it should make
 * a request to the your site which includes that OpenID URL.
 *
 * First, the application should instantiate the Auth_OpenID_Consumer
 * class using the store of choice (Auth_OpenID_FileStore or one of
 * the SQL-based stores).  If the application has any sort of session
 * framework that provides per-client state management, a dict-like
 * object to access the session should be passed as the optional
 * second parameter.  (The default behavior is to use PHP's standard
 * session machinery.)
 *
 * Next, the application should call the Auth_OpenID_Consumer object's
 * 'begin' method.  This method takes the OpenID URL.  The 'begin'
 * method returns an Auth_OpenID_AuthRequest object.
 *
 * Next, the application should call the 'redirectURL' method of the
 * Auth_OpenID_AuthRequest object.  The 'return_to' URL parameter is
 * the URL that the OpenID server will send the user back to after
 * attempting to verify his or her identity.  The 'trust_root' is the
 * URL (or URL pattern) that identifies your web site to the user when
 * he or she is authorizing it.  Send a redirect to the resulting URL
 * to the user's browser.
 *
 * That's the first half of the authentication process.  The second
 * half of the process is done after the user's ID server sends the
 * user's browser a redirect back to your site to complete their
 * login.
 *
 * When that happens, the user will contact your site at the URL given
 * as the 'return_to' URL to the Auth_OpenID_AuthRequest::redirectURL
 * call made above.  The request will have several query parameters
 * added to the URL by the identity server as the information
 * necessary to finish the request.
 *
 * Lastly, instantiate an Auth_OpenID_Consumer instance as above and
 * call its 'complete' method, passing in all the received query
 * arguments.
 *
 * There are multiple possible return types possible from that
 * method. These indicate the whether or not the login was successful,
 * and include any additional information appropriate for their type.
 *
 * PHP versions 4 and 5
 *
 * LICENSE: See the COPYING file included in this distribution.
 *
 * @package OpenID
 * @author JanRain, Inc. <[e-mail]>
 * @copyright 2005 Janrain, Inc.
 * @license http://www.gnu.org/copyleft/lesser.html LGPL
 */

/**
 * Require utility classes and functions for the consumer.
 */
require_once "Auth/OpenID.php";
require_once "Auth/OpenID/HMACSHA1.php";
require_once "Auth/OpenID/Association.php";
require_once "Auth/OpenID/CryptUtil.php";
require_once "Auth/OpenID/DiffieHellman.php";
require_once "Auth/OpenID/KVForm.php";
require_once "Auth/OpenID/Discover.php";
require_once "Services/Yadis/Manager.php";
require_once "Services/Yadis/XRI.php";

/**
 * This is the status code returned when the complete method returns
 * successfully.
 */
define('Auth_OpenID_SUCCESS', 'success');

/**
 * Status to indicate cancellation of OpenID authentication.
 */
define('Auth_OpenID_CANCEL', 'cancel');

/**
 * This is the status code completeAuth returns when the value it
 * received indicated an invalid login.
 */
define('Auth_OpenID_FAILURE', 'failure');

/**
 * This is the status code completeAuth returns when the
 * {@link Auth_OpenID_Consumer} instance is in immediate mode, and the
 * identity server sends back a URL to send the user to to complete his
 * or her login.
 */
define('Auth_OpenID_SETUP_NEEDED', 'setup needed');

/**
 * This is the status code beginAuth returns when the page fetched
 * from the entered OpenID URL doesn't contain the necessary link tags
 * to function as an identity page.
 */
define('Auth_OpenID_PARSE_ERROR', 'parse error');

/**
 * This is the characters that the nonces are made from.
 */
define('Auth_OpenID_DEFAULT_NONCE_CHRS',"abcdefghijklmnopqrstuvwxyz" .
       "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789");

/**
 * An OpenID consumer implementation that performs discovery and does
 * session management.  See the Consumer.php file documentation for
 * more information.
 *
 * @package OpenID
 */
class Auth_OpenID_Consumer {

    /**
     * @access private
     */
    var $session_key_prefix = "_openid_consumer_";

    /**
     * @access private
     */
    var $_token_suffix = "last_token";

    /**
     * Initialize a Consumer instance.
     *
     * You should create a new instance of the Consumer object with
     * every HTTP request that handles OpenID transactions.
     *
     * @param Auth_OpenID_OpenIDStore $store This must be an object
     * that implements the interface in {@link
     * Auth_OpenID_OpenIDStore}.  Several concrete implementations are
     * provided, to cover most common use cases.  For stores backed by
     * MySQL, PostgreSQL, or SQLite, see the {@link
     * Auth_OpenID_SQLStore} class and its sublcasses.  For a
     * filesystem-backed store, see the {@link Auth_OpenID_FileStore}
     * module.  As a last resort, if it isn't possible for the server
     * to store state at all, an instance of {@link
     * Auth_OpenID_DumbStore} can be used.
     *
     * @param mixed session An object which implements the interface
     * of the Services_Yadis_Session class.  Particularly, this object
     * is expected to have these methods: get($key), set($key,
     * $value), and del($key).  This defaults to a session object
     * which wraps PHP's native session machinery.  You should only
     * need to pass something here if you have your own sessioning
     * implementation.
     */
    function Auth_OpenID_Consumer(&$store, $session = null)
    {
        if ($session === null) {
            $session = new Services_Yadis_PHPSession();
        }

        $this->session =& $session;
        $this->consumer =& new Auth_OpenID_GenericConsumer($store);
        $this->_token_key = $this->session_key_prefix . $this->_token_suffix;
    }

    /**
     * Start the OpenID authentication process. See steps 1-2 in the
     * overview at the top of this file.
     *
     * @param User_url: Identity URL given by the user. This method
     * performs a textual transformation of the URL to try and make
     * sure it is normalized. For example, a user_url of example.com
     * will be normalized to http://example.com/ normalizing and
     * resolving any redirects the server might issue.
     *
     * @return Auth_OpenID_AuthRequest $auth_request An object
     * containing the discovered information will be returned, with a
     * method for building a redirect URL to the server, as described
     * in step 3 of the overview. This object may also be used to add
     * extension arguments to the request, using its 'addExtensionArg'
     * method.
     */
    function begin($user_url)
    {
        $discoverMethod = '_Auth_OpenID_discoverServiceList';
        $openid_url = $user_url;

        if (Services_Yadis_identifierScheme($user_url) == 'XRI') {
            $discoverMethod = '_Auth_OpenID_discoverXRIServiceList';
        } else {
            $openid_url = Auth_OpenID::normalizeUrl($user_url);
        }

        $disco =& new Services_Yadis_Discovery($this->session,
                                               $openid_url,
                                               $this->session_key_prefix);

        // Set the 'stale' attribute of the manager.  If discovery
        // fails in a fatal way, the stale flag will cause the manager
        // to be cleaned up next time discovery is attempted.

        $m = $disco->getManager();
        $loader = new Services_Yadis_ManagerLoader();

        if ($m) {
            if ($m->stale) {
                $disco->destroyManager();
            } else {
                $m->stale = true;
                $disco->session->set($disco->session_key,
                                     serialize($loader->toSession($m)));
            }
        }

        $endpoint = $disco->getNextService($discoverMethod,
                                           $this->consumer->fetcher);

        // Reset the 'stale' attribute of the manager.
        $m =& $disco->getManager();
        if ($m) {
            $m->stale = false;
            $disco->session->set($disco->session_key,
                                 serialize($loader->toSession($m)));
        }

        if ($endpoint === null) {
            return null;
        } else {
            return $this->beginWithoutDiscovery($endpoint);
        }
    }

    /**
     * Start OpenID verification without doing OpenID server
     * discovery. This method is used internally by Consumer.begin
     * after discovery is performed, and exists to provide an
     * interface for library users needing to perform their own
     * discovery.
     *
     * @param Auth_OpenID_ServiceEndpoint $endpoint an OpenID service
     * endpoint descriptor.
     *
     * @return Auth_OpenID_AuthRequest $auth_request An OpenID
     * authentication request object.
     */
    function &beginWithoutDiscovery($endpoint)
    {
        $loader = new Auth_OpenID_ServiceEndpointLoader();
        $auth_req = $this->consumer->begin($endpoint);
        $this->session->set($this->_token_key,
              $loader->toSession($auth_req->endpoint));
        return $auth_req;
    }

    /**
     * Called to interpret the server's response to an OpenID
     * request. It is called in step 4 of the flow described in the
     * consumer overview.
     *
     * @param array $query An array of the query parameters (key =>
     * value pairs) for this HTTP request.
     *
     * @return Auth_OpenID_ConsumerResponse $response A instance of an
     * Auth_OpenID_ConsumerResponse subclass. The type of response is
     * indicated by the status attribute, which will be one of
     * SUCCESS, CANCEL, FAILURE, or SETUP_NEEDED.
     */
    function complete($query)
    {
        $query = Auth_OpenID::fixArgs($query);

        $loader = new Auth_OpenID_ServiceEndpointLoader();
        $endpoint_data = $this->session->get($this->_token_key);
        $endpoint =
            $loader->fromSession($endpoint_data);

        if ($endpoint === null) {
            $response = new Auth_OpenID_FailureResponse(null,
                                                   'No session state found');
        } else {
            $response = $this->consumer->complete($query, $endpoint);
            $this->session->del($this->_token_key);
        }

        if (in_array($response->status, array(Auth_OpenID_SUCCESS,
                                              Auth_OpenID_CANCEL))) {
            if ($response->identity_url !== null) {
                $disco = new Services_Yadis_Discovery($this->session,
                                                  $response->identity_url,
                                                  $this->session_key_prefix);
                $disco->cleanup();