some tools we'll require going forward

2 files changed, 1683 insertions, 0 deletions

diff --git a/library/facebook.php b/library/facebook.php
new file mode 100644
index 000000000..eebe3b464
--- /dev/null
+++ b/library/facebook.php
@@ -0,0 +1,955 @@
+<?php
+
+if (!function_exists('curl_init')) {
+  throw new Exception('Facebook needs the CURL PHP extension.');
+}
+if (!function_exists('json_decode')) {
+  throw new Exception('Facebook needs the JSON PHP extension.');
+}
+
+/**
+ * Thrown when an API call returns an exception.
+ *
+ * @author Naitik Shah <naitik@facebook.com>
+ */
+class FacebookApiException extends Exception
+{
+  /**
+   * The result from the API server that represents the exception information.
+   */
+  protected $result;
+
+  /**
+   * Make a new API Exception with the given result.
+   *
+   * @param Array $result the result from the API server
+   */
+  public function __construct($result) {
+    $this->result = $result;
+
+    $code = isset($result['error_code']) ? $result['error_code'] : 0;
+
+    if (isset($result['error_description'])) {
+      // OAuth 2.0 Draft 10 style
+      $msg = $result['error_description'];
+    } else if (isset($result['error']) && is_array($result['error'])) {
+      // OAuth 2.0 Draft 00 style
+      $msg = $result['error']['message'];
+    } else if (isset($result['error_msg'])) {
+      // Rest server style
+      $msg = $result['error_msg'];
+    } else {
+      $msg = 'Unknown Error. Check getResult()';
+    }
+
+    parent::__construct($msg, $code);
+  }
+
+  /**
+   * Return the associated result object returned by the API server.
+   *
+   * @returns Array the result from the API server
+   */
+  public function getResult() {
+    return $this->result;
+  }
+
+  /**
+   * Returns the associated type for the error. This will default to
+   * 'Exception' when a type is not available.
+   *
+   * @return String
+   */
+  public function getType() {
+    if (isset($this->result['error'])) {
+      $error = $this->result['error'];
+      if (is_string($error)) {
+        // OAuth 2.0 Draft 10 style
+        return $error;
+      } else if (is_array($error)) {
+        // OAuth 2.0 Draft 00 style
+        if (isset($error['type'])) {
+          return $error['type'];
+        }
+      }
+    }
+    return 'Exception';
+  }
+
+  /**
+   * To make debugging easier.
+   *
+   * @returns String the string representation of the error
+   */
+  public function __toString() {
+    $str = $this->getType() . ': ';
+    if ($this->code != 0) {
+      $str .= $this->code . ': ';
+    }
+    return $str . $this->message;
+  }
+}
+
+/**
+ * Provides access to the Facebook Platform.
+ *
+ * @author Naitik Shah <naitik@facebook.com>
+ */
+class Facebook
+{
+  /**
+   * Version.
+   */
+  const VERSION = '2.1.2';
+
+  /**
+   * Default options for curl.
+   */
+  public static $CURL_OPTS = array(
+    CURLOPT_CONNECTTIMEOUT => 10,
+    CURLOPT_RETURNTRANSFER => true,
+    CURLOPT_TIMEOUT        => 60,
+    CURLOPT_USERAGENT      => 'facebook-php-2.0',
+  );
+
+  /**
+   * List of query parameters that get automatically dropped when rebuilding
+   * the current URL.
+   */
+  protected static $DROP_QUERY_PARAMS = array(
+    'session',
+    'signed_request',
+  );
+
+  /**
+   * Maps aliases to Facebook domains.
+   */
+  public static $DOMAIN_MAP = array(
+    'api'      => 'https://api.facebook.com/',
+    'api_read' => 'https://api-read.facebook.com/',
+    'graph'    => 'https://graph.facebook.com/',
+    'www'      => 'https://www.facebook.com/',
+  );
+
+  /**
+   * The Application ID.
+   */
+  protected $appId;
+
+  /**
+   * The Application API Secret.
+   */
+  protected $apiSecret;
+
+  /**
+   * The active user session, if one is available.
+   */
+  protected $session;
+
+  /**
+   * The data from the signed_request token.
+   */
+  protected $signedRequest;
+
+  /**
+   * Indicates that we already loaded the session as best as we could.
+   */
+  protected $sessionLoaded = false;
+
+  /**
+   * Indicates if Cookie support should be enabled.
+   */
+  protected $cookieSupport = false;
+
+  /**
+   * Base domain for the Cookie.
+   */
+  protected $baseDomain = '';
+
+  /**
+   * Indicates if the CURL based @ syntax for file uploads is enabled.
+   */
+  protected $fileUploadSupport = false;
+
+  /**
+   * Initialize a Facebook Application.
+   *
+   * The configuration:
+   * - appId: the application ID
+   * - secret: the application secret
+   * - cookie: (optional) boolean true to enable cookie support
+   * - domain: (optional) domain for the cookie
+   * - fileUpload: (optional) boolean indicating if file uploads are enabled
+   *
+   * @param Array $config the application configuration
+   */
+  public function __construct($config) {
+    $this->setAppId($config['appId']);
+    $this->setApiSecret($config['secret']);
+    if (isset($config['cookie'])) {
+      $this->setCookieSupport($config['cookie']);
+    }
+    if (isset($config['domain'])) {
+      $this->setBaseDomain($config['domain']);
+    }
+    if (isset($config['fileUpload'])) {
+      $this->setFileUploadSupport($config['fileUpload']);
+    }
+  }
+
+  /**
+   * Set the Application ID.
+   *
+   * @param String $appId the Application ID
+   */
+  public function setAppId($appId) {
+    $this->appId = $appId;
+    return $this;
+  }
+
+  /**
+   * Get the Application ID.
+   *
+   * @return String the Application ID
+   */
+  public function getAppId() {
+    return $this->appId;
+  }
+
+  /**
+   * Set the API Secret.
+   *
+   * @param String $appId the API Secret
+   */
+  public function setApiSecret($apiSecret) {
+    $this->apiSecret = $apiSecret;
+    return $this;
+  }
+
+  /**
+   * Get the API Secret.
+   *
+   * @return String the API Secret
+   */
+  public function getApiSecret() {
+    return $this->apiSecret;
+  }
+
+  /**
+   * Set the Cookie Support status.
+   *
+   * @param Boolean $cookieSupport the Cookie Support status
+   */
+  public function setCookieSupport($cookieSupport) {
+    $this->cookieSupport = $cookieSupport;
+    return $this;
+  }
+
+  /**
+   * Get the Cookie Support status.
+   *
+   * @return Boolean the Cookie Support status
+   */
+  public function useCookieSupport() {
+    return $this->cookieSupport;
+  }
+
+  /**
+   * Set the base domain for the Cookie.
+   *
+   * @param String $domain the base domain
+   */
+  public function setBaseDomain($domain) {
+    $this->baseDomain = $domain;
+    return $this;
+  }
+
+  /**
+   * Get the base domain for the Cookie.
+   *
+   * @return String the base domain
+   */
+  public function getBaseDomain() {
+    return $this->baseDomain;
+  }
+
+  /**
+   * Set the file upload support status.
+   *
+   * @param String $domain the base domain
+   */
+  public function setFileUploadSupport($fileUploadSupport) {
+    $this->fileUploadSupport = $fileUploadSupport;
+    return $this;
+  }
+
+  /**
+   * Get the file upload support status.
+   *
+   * @return String the base domain
+   */
+  public function useFileUploadSupport() {
+    return $this->fileUploadSupport;
+  }
+
+  /**
+   * Get the data from a signed_request token
+   *
+   * @return String the base domain
+   */
+  public function getSignedRequest() {
+    if (!$this->signedRequest) {
+      if (isset($_REQUEST['signed_request'])) {
+        $this->signedRequest = $this->parseSignedRequest(
+          $_REQUEST['signed_request']);
+      }
+    }
+    return $this->signedRequest;
+  }
+
+  /**
+   * Set the Session.
+   *
+   * @param Array $session the session
+   * @param Boolean $write_cookie indicate if a cookie should be written. this
+   * value is ignored if cookie support has been disabled.
+   */
+  public function setSession($session=null, $write_cookie=true) {
+    $session = $this->validateSessionObject($session);
+    $this->sessionLoaded = true;
+    $this->session = $session;
+    if ($write_cookie) {
+      $this->setCookieFromSession($session);
+    }
+    return $this;
+  }
+
+  /**
+   * Get the session object. This will automatically look for a signed session
+   * sent via the signed_request, Cookie or Query Parameters if needed.
+   *
+   * @return Array the session
+   */
+  public function getSession() {
+    if (!$this->sessionLoaded) {
+      $session = null;
+      $write_cookie = true;
+
+      // try loading session from signed_request in $_REQUEST
+      $signedRequest = $this->getSignedRequest();
+      if ($signedRequest) {
+        // sig is good, use the signedRequest
+        $session = $this->createSessionFromSignedRequest($signedRequest);
+      }
+
+      // try loading session from $_REQUEST
+      if (!$session && isset($_REQUEST['session'])) {
+        $session = json_decode(
+          get_magic_quotes_gpc()
+            ? stripslashes($_REQUEST['session'])
+            : $_REQUEST['session'],
+          true
+        );
+        $session = $this->validateSessionObject($session);
+      }
+
+      // try loading session from cookie if necessary
+      if (!$session && $this->useCookieSupport()) {
+        $cookieName = $this->getSessionCookieName();
+        if (isset($_COOKIE[$cookieName])) {
+          $session = array();
+          parse_str(trim(
+            get_magic_quotes_gpc()
+              ? stripslashes($_COOKIE[$cookieName])
+              : $_COOKIE[$cookieName],
+            '"'
+          ), $session);
+          $session = $this->validateSessionObject($session);
+          // write only if we need to delete a invalid session cookie
+          $write_cookie = empty($session);
+        }
+      }
+
+      $this->setSession($session, $write_cookie);
+    }
+
+    return $this->session;
+  }
+
+  /**
+   * Get the UID from the session.
+   *
+   * @return String the UID if available
+   */
+  public function getUser() {
+    $session = $this->getSession();
+    return $session ? $session['uid'] : null;
+  }
+
+  /**
+   * Gets a OAuth access token.
+   *
+   * @return String the access token
+   */
+  public function getAccessToken() {
+    $session = $this->getSession();
+    // either user session signed, or app signed
+    if ($session) {
+      return $session['access_token'];
+    } else {
+      return $this->getAppId() .'|'. $this->getApiSecret();
+    }
+  }
+
+  /**
+   * Get a Login URL for use with redirects. By default, full page redirect is
+   * assumed. If you are using the generated URL with a window.open() call in
+   * JavaScript, you can pass in display=popup as part of the $params.
+   *
+   * The parameters:
+   * - next: the url to go to after a successful login
+   * - cancel_url: the url to go to after the user cancels
+   * - req_perms: comma separated list of requested extended perms
+   * - display: can be "page" (default, full page) or "popup"
+   *
+   * @param Array $params provide custom parameters
+   * @return String the URL for the login flow
+   */
+  public function getLoginUrl($params=array()) {
+    $currentUrl = $this->getCurrentUrl();
+    return $this->getUrl(
+      'www',
+      'login.php',
+      array_merge(array(
+        'api_key'         => $this->getAppId(),
+        'cancel_url'      => $currentUrl,
+        'display'         => 'page',
+        'fbconnect'       => 1,
+        'next'            => $currentUrl,
+        'return_session'  => 1,
+        'session_version' => 3,
+        'v'               => '1.0',
+      ), $params)
+    );
+  }
+
+  /**
+   * Get a Logout URL suitable for use with redirects.
+   *
+   * The parameters:
+   * - next: the url to go to after a successful logout
+   *
+   * @param Array $params provide custom parameters
+   * @return String the URL for the logout flow
+   */
+  public function getLogoutUrl($params=array()) {
+    return $this->getUrl(
+      'www',
+      'logout.php',
+      array_merge(array(
+        'next'         => $this->getCurrentUrl(),
+        'access_token' => $this->getAccessToken(),
+      ), $params)
+    );
+  }
+
+  /**
+   * Get a login status URL to fetch the status from facebook.
+   *
+   * The parameters:
+   * - ok_session: the URL to go to if a session is found
+   * - no_session: the URL to go to if the user is not connected
+   * - no_user: the URL to go to if the user is not signed into facebook
+   *
+   * @param Array $params provide custom parameters
+   * @return String the URL for the logout flow
+   */
+  public function getLoginStatusUrl($params=array()) {
+    return $this->getUrl(
+      'www',
+      'extern/login_status.php',
+      array_merge(array(
+        'api_key'         => $this->getAppId(),
+        'no_session'      => $this->getCurrentUrl(),
+        'no_user'         => $this->getCurrentUrl(),
+        'ok_session'      => $this->getCurrentUrl(),
+        'session_version' => 3,
+      ), $params)
+    );
+  }
+
+  /**
+   * Make an API call.
+   *
+   * @param Array $params the API call parameters
+   * @return the decoded response
+   */
+  public function api(/* polymorphic */) {
+    $args = func_get_args();
+    if (is_array($args[0])) {
+      return $this->_restserver($args[0]);
+    } else {
+      return call_user_func_array(array($this, '_graph'), $args);
+    }
+  }
+
+  /**
+   * Invoke the old restserver.php endpoint.
+   *
+   * @param Array $params method call object
+   * @return the decoded response object
+   * @throws FacebookApiException
+   */
+  protected function _restserver($params) {
+    // generic application level parameters
+    $params['api_key'] = $this->getAppId();
+    $params['format'] = 'json-strings';
+
+    $result = json_decode($this->_oauthRequest(
+      $this->getApiUrl($params['method']),
+      $params
+    ), true);
+
+    // results are returned, errors are thrown
+    if (is_array($result) && isset($result['error_code'])) {
+      throw new FacebookApiException($result);
+    }
+    return $result;
+  }
+
+  /**
+   * Invoke the Graph API.
+   *
+   * @param String $path the path (required)
+   * @param String $method the http method (default 'GET')
+   * @param Array $params the query/post data
+   * @return the decoded response object
+   * @throws FacebookApiException
+   */
+  protected function _graph($path, $method='GET', $params=array()) {
+    if (is_array($method) && empty($params)) {
+      $params = $method;
+      $method = 'GET';
+    }
+    $params['method'] = $method; // method override as we always do a POST
+
+    $result = json_decode($this->_oauthRequest(
+      $this->getUrl('graph', $path),
+      $params
+    ), true);
+
+    // results are returned, errors are thrown
+    if (is_array($result) && isset($result['error'])) {
+      $e = new FacebookApiException($result);
+      switch ($e->getType()) {
+        // OAuth 2.0 Draft 00 style
+        case 'OAuthException':
+        // OAuth 2.0 Draft 10 style
+        case 'invalid_token':
+          $this->setSession(null);
+      }
+      throw $e;
+    }
+    return $result;
+  }
+
+  /**
+   * Make a OAuth Request
+   *
+   * @param String $path the path (required)
+   * @param Array $params the query/post data
+   * @return the decoded response object
+   * @throws FacebookApiException
+   */
+  protected function _oauthRequest($url, $params) {
+    if (!isset($params['access_token'])) {
+      $params['access_token'] = $this->getAccessToken();
+    }
+
+    // json_encode all params values that are not strings
+    foreach ($params as $key => $value) {
+      if (!is_string($value)) {
+        $params[$key] = json_encode($value);
+      }
+    }
+    return $this->makeRequest($url, $params);
+  }
+
+  /**
+   * Makes an HTTP request. This method can be overriden by subclasses if
+   * developers want to do fancier things or use something other than curl to
+   * make the request.
+   *
+   * @param String $url the URL to make the request to
+   * @param Array $params the parameters to use for the POST body
+   * @param CurlHandler $ch optional initialized curl handle
+   * @return String the response text
+   */
+  protected function makeRequest($url, $params, $ch=null) {
+    if (!$ch) {
+      $ch = curl_init();
+    }
+
+    $opts = self::$CURL_OPTS;
+    if ($this->useFileUploadSupport()) {
+      $opts[CURLOPT_POSTFIELDS] = $params;
+    } else {
+      $opts[CURLOPT_POSTFIELDS] = http_build_query($params, null, '&');
+    }
+    $opts[CURLOPT_URL] = $url;
+
+    // disable the 'Expect: 100-continue' behaviour. This causes CURL to wait
+    // for 2 seconds if the server does not support this header.
+    if (isset($opts[CURLOPT_HTTPHEADER])) {
+      $existing_headers = $opts[CURLOPT_HTTPHEADER];
+      $existing_headers[] = 'Expect:';
+      $opts[CURLOPT_HTTPHEADER] = $existing_headers;
+    } else {
+      $opts[CURLOPT_HTTPHEADER] = array('Expect:');
+    }
+
+    curl_setopt_array($ch, $opts);
+    $result = curl_exec($ch);
+    if ($result === false) {
+      $e = new FacebookApiException(array(
+        'error_code' => curl_errno($ch),
+        'error'      => array(
+          'message' => curl_error($ch),
+          'type'    => 'CurlException',
+        ),
+      ));
+      curl_close($ch);
+      throw $e;
+    }
+    curl_close($ch);
+    return $result;
+  }
+
+  /**
+   * The name of the Cookie that contains the session.
+   *
+   * @return String the cookie name
+   */
+  protected function getSessionCookieName() {
+    return 'fbs_' . $this->getAppId();
+  }
+
+  /**
+   * Set a JS Cookie based on the _passed in_ session. It does not use the
+   * currently stored session -- you need to explicitly pass it in.
+   *
+   * @param Array $session the session to use for setting the cookie
+   */
+  protected function setCookieFromSession($session=null) {
+    if (!$this->useCookieSupport()) {
+      return;
+    }
+
+    $cookieName = $this->getSessionCookieName();
+    $value = 'deleted';
+    $expires = time() - 3600;
+    $domain = $this->getBaseDomain();
+    if ($session) {
+      $value = '"' . http_build_query($session, null, '&') . '"';
+      if (isset($session['base_domain'])) {
+        $domain = $session['base_domain'];
+      }
+      $expires = $session['expires'];
+    }
+
+    // prepend dot if a domain is found
+    if ($domain) {
+      $domain = '.' . $domain;
+    }
+
+    // if an existing cookie is not set, we dont need to delete it
+    if ($value == 'deleted' && empty($_COOKIE[$cookieName])) {
+      return;
+    }
+
+    if (headers_sent()) {
+      self::errorLog('Could not set cookie. Headers already sent.');
+
+    // ignore for code coverage as we will never be able to setcookie in a CLI
+    // environment
+    // @codeCoverageIgnoreStart
+    } else {
+      setcookie($cookieName, $value, $expires, '/', $domain);
+    }
+    // @codeCoverageIgnoreEnd
+  }
+
+  /**
+   * Validates a session_version=3 style session object.
+   *
+   * @param Array $session the session object
+   * @return Array the session object if it validates, null otherwise
+   */
+  protected function validateSessionObject($session) {
+    // make sure some essential fields exist
+    if (is_array($session) &&
+        isset($session['uid']) &&
+        isset($session['access_token']) &&
+        isset($session['sig'])) {
+      // validate the signature
+      $session_without_sig = $session;
+      unset($session_without_sig['sig']);
+      $expected_sig = self::generateSignature(
+        $session_without_sig,
+        $this->getApiSecret()
+      );
+      if ($session['sig'] != $expected_sig) {
+        self::errorLog('Got invalid session signature in cookie.');
+        $session = null;
+      }
+      // check expiry time
+    } else {
+      $session = null;
+    }
+    return $session;
+  }
+
+  /**
+   * Returns something that looks like our JS session object from the
+   * signed token's data
+   *
+   * TODO: Nuke this once the login flow uses OAuth2
+   *
+   * @param Array the output of getSignedRequest
+   * @return Array Something that will work as a session
+   */
+  protected function createSessionFromSignedRequest($data) {
+    if (!isset($data['oauth_token'])) {
+      return null;
+    }
+
+    $session = array(
+      'uid'          => $data['user_id'],
+      'access_token' => $data['oauth_token'],
+      'expires'      => $data['expires'],
+    );
+
+    // put a real sig, so that validateSignature works
+    $session['sig'] = self::generateSignature(
+      $session,
+      $this->getApiSecret()
+    );
+
+    return $session;
+  }
+
+  /**
+   * Parses a signed_request and validates the signature.
+   * Then saves it in $this->signed_data
+   *
+   * @param String A signed token
+   * @param Boolean Should we remove the parts of the payload that
+   *                are used by the algorithm?
+   * @return Array the payload inside it or null if the sig is wrong
+   */
+  protected function parseSignedRequest($signed_request) {
+    list($encoded_sig, $payload) = explode('.', $signed_request, 2);
+
+    // decode the data
+    $sig = self::base64UrlDecode($encoded_sig);
+    $data = json_decode(self::base64UrlDecode($payload), true);
+
+    if (strtoupper($data['algorithm']) !== 'HMAC-SHA256') {
+      self::errorLog('Unknown algorithm. Expected HMAC-SHA256');
+      return null;
+    }
+
+    // check sig
+    $expected_sig = hash_hmac('sha256', $payload,
+                              $this->getApiSecret(), $raw = true);
+    if ($sig !== $expected_sig) {
+      self::errorLog('Bad Signed JSON signature!');
+      return null;
+    }
+
+    return $data;
+  }
+
+  /**
+   * Build the URL for api given parameters.
+   *
+   * @param $method String the method name.
+   * @return String the URL for the given parameters
+   */
+  protected function getApiUrl($method) {
+    static $READ_ONLY_CALLS =
+      array('admin.getallocation' => 1,
+            'admin.getappproperties' => 1,
+            'admin.getbannedusers' => 1,
+            'admin.getlivestreamvialink' => 1,
+            'admin.getmetrics' => 1,
+            'admin.getrestrictioninfo' => 1,
+            'application.getpublicinfo' => 1,
+            'auth.getapppublickey' => 1,
+            'auth.getsession' => 1,
+            'auth.getsignedpublicsessiondata' => 1,
+            'comments.get' => 1,
+            'connect.getunconnectedfriendscount' => 1,
+            'dashboard.getactivity' => 1,
+            'dashboard.getcount' => 1,
+            'dashboard.getglobalnews' => 1,
+            'dashboard.getnews' => 1,
+            'dashboard.multigetcount' => 1,
+            'dashboard.multigetnews' => 1,
+            'data.getcookies' => 1,
+            'events.get' => 1,
+            'events.getmembers' => 1,
+            'fbml.getcustomtags' => 1,
+            'feed.getappfriendstories' => 1,
+            'feed.getregisteredtemplatebundlebyid' => 1,
+            'feed.getregisteredtemplatebundles' => 1,
+            'fql.multiquery' => 1,
+            'fql.query' => 1,
+            'friends.arefriends' => 1,
+            'friends.get' => 1,
+            'friends.getappusers' => 1,
+            'friends.getlists' => 1,
+            'friends.getmutualfriends' => 1,
+            'gifts.get' => 1,
+            'groups.get' => 1,
+            'groups.getmembers' => 1,
+            'intl.gettranslations' => 1,
+            'links.get' => 1,
+            'notes.get' => 1,
+            'notifications.get' => 1,
+            'pages.getinfo' => 1,
+            'pages.isadmin' => 1,
+            'pages.isappadded' => 1,
+            'pages.isfan' => 1,
+            'permissions.checkavailableapiaccess' => 1,
+            'permissions.checkgrantedapiaccess' => 1,
+            'photos.get' => 1,
+            'photos.getalbums' => 1,
+            'photos.gettags' => 1,
+            'profile.getinfo' => 1,
+            'profile.getinfooptions' => 1,
+            'stream.get' => 1,
+            'stream.getcomments' => 1,
+            'stream.getfilters' => 1,
+            'users.getinfo' => 1,
+            'users.getloggedinuser' => 1,
+            'users.getstandardinfo' => 1,
+            'users.hasapppermission' => 1,
+            'users.isappuser' => 1,
+            'users.isverified' => 1,
+            'video.getuploadlimits' => 1);
+    $name = 'api';
+    if (isset($READ_ONLY_CALLS[strtolower($method)])) {
+      $name = 'api_read';
+    }
+    return self::getUrl($name, 'restserver.php');
+  }
+
+  /**
+   * Build the URL for given domain alias, path and parameters.
+   *
+   * @param $name String the name of the domain
+   * @param $path String optional path (without a leading slash)
+   * @param $params Array optional query parameters
+   * @return String the URL for the given parameters
+   */
+  protected function getUrl($name, $path='', $params=array()) {
+    $url = self::$DOMAIN_MAP[$name];
+    if ($path) {
+      if ($path[0] === '/') {
+        $path = substr($path, 1);
+      }
+      $url .= $path;
+    }
+    if ($params) {
+      $url .= '?' . http_build_query($params, null, '&');
+    }
+    return $url;
+  }
+
+  /**
+   * Returns the Current URL, stripping it of known FB parameters that should
+   * not persist.
+   *
+   * @return String the current URL
+   */
+  protected function getCurrentUrl() {
+    $protocol = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on'
+      ? 'https://'
+      : 'http://';
+    $currentUrl = $protocol . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
+    $parts = parse_url($currentUrl);
+
+    // drop known fb params
+    $query = '';
+    if (!empty($parts['query'])) {
+      $params = array();
+      parse_str($parts['query'], $params);
+      foreach(self::$DROP_QUERY_PARAMS as $key) {
+        unset($params[$key]);
+      }
+      if (!empty($params)) {
+        $query = '?' . http_build_query($params, null, '&');
+      }
+    }
+
+    // use port if non default
+    $port =
+      isset($parts['port']) &&
+      (($protocol === 'http://' && $parts['port'] !== 80) ||
+       ($protocol === 'https://' && $parts['port'] !== 443))
+      ? ':' . $parts['port'] : '';
+
+    // rebuild
+    return $protocol . $parts['host'] . $port . $parts['path'] . $query;
+  }
+
+  /**
+   * Generate a signature for the given params and secret.
+   *
+   * @param Array $params the parameters to sign
+   * @param String $secret the secret to sign with
+   * @return String the generated signature
+   */
+  protected static function generateSignature($params, $secret) {
+    // work with sorted data
+    ksort($params);
+
+    // generate the base string
+    $base_string = '';
+    foreach($params as $key => $value) {
+      $base_string .= $key . '=' . $value;
+    }
+    $base_string .= $secret;
+
+    return md5($base_string);
+  }
+
+  /**
+   * Prints to the error log if you aren't in command line mode.
+   *
+   * @param String log message
+   */
+  protected static function errorLog($msg) {
+    // disable error log if we are running in a CLI environment
+    // @codeCoverageIgnoreStart
+    if (php_sapi_name() != 'cli') {
+      error_log($msg);
+    }
+    // uncomment this if you want to see the errors on the page
+    // print 'error_log: '.$msg."\n";
+    // @codeCoverageIgnoreEnd
+  }
+
+  /**
+   * Base64 encoding that doesn't need to be urlencode()ed.
+   * Exactly the same as base64_encode except it uses
+   *   - instead of +
+   *   _ instead of /
+   *
+   * @param String base64UrlEncodeded string
+   */
+  protected static function base64UrlDecode($input) {
+    return base64_decode(strtr($input, '-_', '+/'));
+  }
+}
diff --git a/library/oauth.php b/library/oauth.php
new file mode 100644
index 000000000..caf1a0839
--- /dev/null
+++ b/library/oauth.php
@@ -0,0 +1,728 @@
+<?php
+
+//ini_set('display_errors', 1);
+//error_reporting(E_ALL | E_STRICT);
+
+// Regex to filter out the client identifier
+// (described in Section 2 of IETF draft)
+// IETF draft does not prescribe a format for these, however
+// I've arbitrarily chosen alphanumeric strings with hyphens and underscores, 3-12 characters long
+// Feel free to change.
+define("REGEX_CLIENT_ID", "/^[a-z0-9-_]{3,12}$/i");
+
+// Used to define the name of the OAuth access token parameter (POST/GET/etc.)
+// IETF Draft sections 5.2 and 5.3 specify that it should be called "oauth_token"
+// but other implementations use things like "access_token"
+// I won't be heartbroken if you change it, but it might be better to adhere to the spec
+define("OAUTH_TOKEN_PARAM_NAME", "oauth_token");
+
+// Client types (for client authorization)
+//define("WEB_SERVER_CLIENT_TYPE", "web_server");
+//define("USER_AGENT_CLIENT_TYPE", "user_agent");
+//define("REGEX_CLIENT_TYPE", "/^(web_server|user_agent)$/");
+define("ACCESS_TOKEN_AUTH_RESPONSE_TYPE", "token");
+define("AUTH_CODE_AUTH_RESPONSE_TYPE", "code");
+define("CODE_AND_TOKEN_AUTH_RESPONSE_TYPE", "code-and-token");
+define("REGEX_AUTH_RESPONSE_TYPE", "/^(token|code|code-and-token)$/");
+
+// Grant Types (for token obtaining)
+define("AUTH_CODE_GRANT_TYPE", "authorization-code");
+define("USER_CREDENTIALS_GRANT_TYPE", "basic-credentials");
+define("ASSERTION_GRANT_TYPE", "assertion");
+define("REFRESH_TOKEN_GRANT_TYPE", "refresh-token");
+define("NONE_GRANT_TYPE", "none");
+define("REGEX_TOKEN_GRANT_TYPE", "/^(authorization-code|basic-credentials|assertion|refresh-token|none)$/");
+
+/* Error handling constants */
+
+// HTTP status codes
+define("ERROR_NOT_FOUND", "404 Not Found");
+define("ERROR_BAD_REQUEST", "400 Bad Request");
+
+// TODO: Extend for i18n
+
+// "Official" OAuth 2.0 errors
+define("ERROR_REDIRECT_URI_MISMATCH", "redirect-uri-mismatch");
+define("ERROR_INVALID_CLIENT_CREDENTIALS", "invalid-client-credentials");
+define("ERROR_UNAUTHORIZED_CLIENT", "unauthorized-client");
+define("ERROR_USER_DENIED", "access-denied");
+define("ERROR_INVALID_REQUEST", "invalid-request");
+define("ERROR_INVALID_CLIENT_ID", "invalid-client-id");
+define("ERROR_UNSUPPORTED_RESPONSE_TYPE", "unsupported-response-type");
+define("ERROR_INVALID_SCOPE", "invalid-scope");
+define("ERROR_INVALID_GRANT", "invalid-grant");
+
+// Protected resource errors
+define("ERROR_INVALID_TOKEN", "invalid-token");
+define("ERROR_EXPIRED_TOKEN", "expired-token");
+define("ERROR_INSUFFICIENT_SCOPE", "insufficient-scope");
+
+// Messages
+define("ERROR_INVALID_RESPONSE_TYPE", "Invalid response type.");
+
+// Errors that we made up
+
+// Error for trying to use a grant type that we haven't implemented
+define("ERROR_UNSUPPORTED_GRANT_TYPE", "unsupported-grant-type");
+
+abstract class OAuth2 {
+
+    /* Subclasses must implement the following functions */
+
+    // Make sure that the client id is valid
+    // If a secret is required, check that they've given the right one
+    // Must return false if the client credentials are invalid
+    abstract protected function auth_client_credentials($client_id, $client_secret = null);
+
+    // OAuth says we should store request URIs for each registered client
+    // Implement this function to grab the stored URI for a given client id
+    // Must return false if the given client does not exist or is invalid
+    abstract protected function get_redirect_uri($client_id);
+
+    // We need to store and retrieve access token data as we create and verify tokens
+    // Implement these functions to do just that
+
+    // Look up the supplied token id from storage, and return an array like:
+    //
+    //  array(
+    //      "client_id" => <stored client id>,
+    //      "expires" => <stored expiration timestamp>,
+    //      "scope" => <stored scope (may be null)
+    //  )
+    //
+    //  Return null if the supplied token is invalid
+    //
+    abstract protected function get_access_token($token_id);
+
+    // Store the supplied values
+    abstract protected function store_access_token($token_id, $client_id, $expires, $scope = null);
+
+    /*
+     *
+     * Stuff that should get overridden by subclasses
+     *
+     * I don't want to make these abstract, because then subclasses would have
+     * to implement all of them, which is too much work.
+     *
+     * So they're just stubs.  Override the ones you need.
+     *
+     */
+
+    // You should override this function with something,
+    // or else your OAuth provider won't support any grant types!
+    protected function get_supported_grant_types() {
+        // If you support all grant types, then you'd do:
+        // return array(
+        //             AUTH_CODE_GRANT_TYPE,
+        //             USER_CREDENTIALS_GRANT_TYPE,
+        //             ASSERTION_GRANT_TYPE,
+        //             REFRESH_TOKEN_GRANT_TYPE,
+        //             NONE_GRANT_TYPE
+        //     );
+
+        return array();
+    }
+
+    // You should override this function with your supported response types
+    protected function get_supported_auth_response_types() {
+        return array(
+            AUTH_CODE_AUTH_RESPONSE_TYPE,
+            ACCESS_TOKEN_AUTH_RESPONSE_TYPE,
+            CODE_AND_TOKEN_AUTH_RESPONSE_TYPE
+        );
+    }
+
+    // If you want to support scope use, then have this function return a list
+    // of all acceptable scopes (used to throw the invalid-scope error)
+    protected function get_supported_scopes() {
+        //  Example:
+        //  return array("my-friends", "photos", "whatever-else");
+        return array();
+    }
+
+    // If you want to restrict clients to certain authorization response types,
+    // override this function
+    // Given a client identifier and auth type, return true or false
+    // (auth type would be one of the values contained in REGEX_AUTH_RESPONSE_TYPE)
+    protected function authorize_client_response_type($client_id, $response_type) {
+        return true;
+    }
+
+    // If you want to restrict clients to certain grant types, override this function
+    // Given a client identifier and grant type, return true or false
+    protected function authorize_client($client_id, $grant_type) {
+        return true;
+    }
+
+    /* Functions that help grant access tokens for various grant types */
+
+    // Fetch authorization code data (probably the most common grant type)
+    // IETF Draft 4.1.1: http://tools.ietf.org/html/draft-ietf-oauth-v2-08#section-4.1.1
+    // Required for AUTH_CODE_GRANT_TYPE
+    protected function get_stored_auth_code($code) {
+        // Retrieve the stored data for the given authorization code
+        // Should return:
+        //
+        // array (
+        //  "client_id" => <stored client id>,
+        //  "redirect_uri" => <stored redirect URI>,
+        //  "expires" => <stored code expiration time>,
+        //  "scope" => <stored scope values (space-separated string), or can be omitted if scope is unused>
+        // )
+        //
+        // Return null if the code is invalid.
+
+        return null;
+    }
+
+    // Take the provided authorization code values and store them somewhere (db, etc.)
+    // Required for AUTH_CODE_GRANT_TYPE
+    protected function store_auth_code($code, $client_id, $redirect_uri, $expires, $scope) {
+        // This function should be the storage counterpart to get_stored_auth_code
+
+        // If storage fails for some reason, we're not currently checking
+        // for any sort of success/failure, so you should bail out of the
+        // script and provide a descriptive fail message
+    }
+
+    // Grant access tokens for basic user credentials
+    // IETF Draft 4.1.2: http://tools.ietf.org/html/draft-ietf-oauth-v2-08#section-4.1.2
+    // Required for USER_CREDENTIALS_GRANT_TYPE
+    protected function check_user_credentials($client_id, $username, $password) {
+        // Check the supplied username and password for validity
+        // You can also use the $client_id param to do any checks required
+        // based on a client, if you need that
+        // If the username and password are invalid, return false
+
+        // If the username and password are valid, and you want to verify the scope of
+        // a user's access, return an array with the scope values, like so:
+        //
+        // array (
+        //  "scope" => <stored scope values (space-separated string)>
+        // )
+        //
+        // We'll check the scope you provide against the requested scope before
+        // providing an access token.
+        //
+        // Otherwise, just return true.
+
+        return false;
+    }
+
+    // Grant access tokens for assertions
+    // IETF Draft 4.1.3: http://tools.ietf.org/html/draft-ietf-oauth-v2-08#section-4.1.3
+    // Required for ASSERTION_GRANT_TYPE
+    protected function check_assertion($client_id, $assertion_type, $assertion) {
+        // Check the supplied assertion for validity
+        // You can also use the $client_id param to do any checks required
+        // based on a client, if you need that
+        // If the assertion is invalid, return false
+
+        // If the assertion is valid, and you want to verify the scope of
+        // an access request, return an array with the scope values, like so:
+        //
+        // array (
+        //  "scope" => <stored scope values (space-separated string)>
+        // )
+        //
+        // We'll check the scope you provide against the requested scope before
+        // providing an access token.
+        //
+        // Otherwise, just return true.
+
+        return false;
+    }
+
+    // Grant refresh access tokens
+    // IETF Draft 4.1.4: http://tools.ietf.org/html/draft-ietf-oauth-v2-08#section-4.1.4
+    // Required for REFRESH_TOKEN_GRANT_TYPE
+    protected function get_refresh_token($refresh_token) {
+        // Retrieve the stored data for the given refresh token
+        // Should return:
+        //
+        // array (
+        //  "client_id" => <stored client id>,
+        //  "expires" => <refresh token expiration time>,
+        //  "scope" => <stored scope values (space-separated string), or can be omitted if scope is unused>
+        // )
+        //
+        // Return null if the token id is invalid.
+
+        return null;
+    }
+
+    // Store refresh access tokens
+    // Required for REFRESH_TOKEN_GRANT_TYPE
+    protected function store_refresh_token($token, $client_id, $expires, $scope = null) {
+        // If storage fails for some reason, we're not currently checking
+        // for any sort of success/failure, so you should bail out of the
+        // script and provide a descriptive fail message
+
+        return;
+    }
+
+    // Grant access tokens for the "none" grant type
+    // Not really described in the IETF Draft, so I just left a method stub...do whatever you want!
+    // Required for NONE_GRANT_TYPE
+    protected function check_none_access($client_id) {
+        return false;
+    }
+
+    protected function get_default_authentication_realm() {
+        // Change this to whatever authentication realm you want to send in a WWW-Authenticate header
+        return "Service";
+    }
+
+    /* End stuff that should get overridden */
+
+    private $access_token_lifetime = 3600;
+    private $auth_code_lifetime = 30;
+    private $refresh_token_lifetime = 1209600; // Two weeks
+
+    public function __construct($access_token_lifetime = 3600, $auth_code_lifetime = 30, $refresh_token_lifetime = 1209600) {
+        $this->access_token_lifetime = $access_token_lifetime;
+        $this->auth_code_lifetime = $auth_code_lifetime;
+        $this->refresh_token_lifetime = $refresh_token_lifetime;
+    }
+
+    /* Resource protecting (Section 5) */
+
+    // Check that a valid access token has been provided
+    //
+    // The scope parameter defines any required scope that the token must have
+    // If a scope param is provided and the token does not have the required scope,
+    // we bounce the request
+    //
+    // Some implementations may choose to return a subset of the protected resource
+    // (i.e. "public" data) if the user has not provided an access token
+    // or if the access token is invalid or expired
+    //
+    // The IETF spec says that we should send a 401 Unauthorized header and bail immediately
+    // so that's what the defaults are set to
+    //
+    // Here's what each parameter does:
+    // $scope = A space-separated string of required scope(s), if you want to check for scope
+    // $exit_not_present = If true and no access token is provided, send a 401 header and exit, otherwise return false
+    // $exit_invalid = If true and the implementation of get_access_token returns null, exit, otherwise return false
+    // $exit_expired = If true and the access token has expired, exit, otherwise return false
+    // $exit_scope = If true the access token does not have the required scope(s), exit, otherwise return false
+    // $realm = If you want to specify a particular realm for the WWW-Authenticate header, supply it here
+    public function verify_access_token($scope = null, $exit_not_present = true, $exit_invalid = true, $exit_expired = true, $exit_scope = true, $realm = null) {
+        $token_param = $this->get_access_token_param();
+        if ($token_param === false) // Access token was not provided
+            return $exit_not_present ? $this->send_401_unauthorized($realm, $scope) : false;
+
+        // Get the stored token data (from the implementing subclass)
+        $token = $this->get_access_token($token_param);
+        if ($token === null)
+            return $exit_invalid ? $this->send_401_unauthorized($realm, $scope, ERROR_INVALID_TOKEN) : false;
+
+        // Check token expiration (I'm leaving this check separated, later we'll fill in better error messages)
+        if (isset($token["expires"]) && time() > $token["expires"])
+            return $exit_expired ? $this->send_401_unauthorized($realm, $scope, ERROR_EXPIRED_TOKEN) : false;
+
+        // Check scope, if provided
+        // If token doesn't have a scope, it's null/empty, or it's insufficient, then throw an error
+        if ($scope &&
+                (!isset($token["scope"]) || !$token["scope"] || !$this->check_scope($scope, $token["scope"])))
+            return $exit_scope ? $this->send_401_unauthorized($realm, $scope, ERROR_INSUFFICIENT_SCOPE) : false;
+
+        return true;
+    }
+
+
+    // Returns true if everything in required scope is contained in available scope
+    // False if something in required scope is not in available scope
+    private function check_scope($required_scope, $available_scope) {
+        // The required scope should match or be a subset of the available scope
+        if (!is_array($required_scope))
+            $required_scope = explode(" ", $required_scope);
+
+        if (!is_array($available_scope))
+            $available_scope = explode(" ", $available_scope);
+
+        return (count(array_diff($required_scope, $available_scope)) == 0);
+    }
+
+    // Send a 401 unauthorized header with the given realm
+    // and an error, if provided
+    private function send_401_unauthorized($realm, $scope, $error = null) {
+        $realm = $realm === null ? $this->get_default_authentication_realm() : $realm;
+
+        $auth_header = "WWW-Authenticate: Token realm='".$realm."'";
+
+        if ($scope)
+            $auth_header .= ", scope='".$scope."'";
+
+        if ($error !== null)
+            $auth_header .= ", error='".$error."'";
+
+        header("HTTP/1.1 401 Unauthorized");
+        header($auth_header);
+
+        exit;
+    }
+
+    // Pulls the access token out of the HTTP request
+    // Either from the Authorization header or GET/POST/etc.
+    // Returns false if no token is present
+    // TODO: Support POST or DELETE
+    private function get_access_token_param() {
+        $auth_header = $this->get_authorization_header();
+
+        if ($auth_header !== false) {
+            // Make sure only the auth header is set
+            if (isset($_GET[OAUTH_TOKEN_PARAM_NAME]) || isset($_POST[OAUTH_TOKEN_PARAM_NAME]))
+                $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+            $auth_header = trim($auth_header);
+
+            // Make sure it's Token authorization
+            if (strcmp(substr($auth_header, 0, 6),"Token ") !== 0)
+                $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+            // Parse the rest of the header
+            if (preg_match('/\s*token\s*="(.+)"/', substr($auth_header, 6), $matches) == 0 || count($matches) < 2)
+                $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+            return $matches[1];
+        }
+
+        if (isset($_GET[OAUTH_TOKEN_PARAM_NAME]))  {
+            if (isset($_POST[OAUTH_TOKEN_PARAM_NAME])) // Both GET and POST are not allowed
+                $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+            return $_GET[OAUTH_TOKEN_PARAM_NAME];
+        }
+
+        if (isset($_POST[OAUTH_TOKEN_PARAM_NAME]))
+            return $_POST[OAUTH_TOKEN_PARAM_NAME];
+
+        return false;
+    }
+
+    /* Access token granting (Section 4) */
+
+    // Grant or deny a requested access token
+    // This would be called from the "/token" endpoint as defined in the spec
+    // Obviously, you can call your endpoint whatever you want
+    public function grant_access_token() {
+        $filters = array(
+            "grant_type" => array("filter" => FILTER_VALIDATE_REGEXP, "options" => array("regexp" => REGEX_TOKEN_GRANT_TYPE), "flags" => FILTER_REQUIRE_SCALAR),
+            "scope" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "code" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "redirect_uri" => array("filter" => FILTER_VALIDATE_URL, "flags" => array(FILTER_FLAG_SCHEME_REQUIRED, FILTER_REQUIRE_SCALAR)),
+            "username" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "password" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "assertion_type" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "assertion" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "refresh_token" => array("flags" => FILTER_REQUIRE_SCALAR),
+        );
+
+        $input = filter_input_array(INPUT_POST, $filters);
+
+        // Grant Type must be specified.
+        if (!$input["grant_type"])
+            $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+        // Make sure we've implemented the requested grant type
+        if (!in_array($input["grant_type"], $this->get_supported_grant_types()))
+            $this->error(ERROR_BAD_REQUEST, ERROR_UNSUPPORTED_GRANT_TYPE);
+
+        // Authorize the client
+        $client = $this->get_client_credentials();
+
+        if ($this->auth_client_credentials($client[0], $client[1]) === false)
+            $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_CLIENT_CREDENTIALS);
+
+        if (!$this->authorize_client($client[0], $input["grant_type"]))
+            $this->error(ERROR_BAD_REQUEST, ERROR_UNAUTHORIZED_CLIENT);
+
+        // Do the granting
+        switch ($input["grant_type"]) {
+            case AUTH_CODE_GRANT_TYPE:
+                if (!$input["code"] || !$input["redirect_uri"])
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+                $stored = $this->get_stored_auth_code($input["code"]);
+
+                if ($stored === null || $input["redirect_uri"] != $stored["redirect_uri"] || $client[0] != $stored["client_id"])
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_GRANT);
+
+                if ($stored["expires"] > time())
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_GRANT);
+
+                break;
+            case USER_CREDENTIALS_GRANT_TYPE:
+                if (!$input["username"] || !$input["password"])
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+                $stored = $this->check_user_credentials($client[0], $input["username"], $input["password"]);
+
+                if ($stored === false)
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_GRANT);
+
+                break;
+            case ASSERTION_GRANT_TYPE:
+                if (!$input["assertion_type"] || !$input["assertion"])
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+                $stored = $this->check_assertion($client[0], $input["assertion_type"], $input["assertion"]);
+
+                if ($stored === false)
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_GRANT);
+
+                break;
+            case REFRESH_TOKEN_GRANT_TYPE:
+                if (!$input["refresh_token"])
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+                $stored = $this->get_refresh_token($input["refresh_token"]);
+
+                if ($stored === null || $client[0] != $stored["client_id"])
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_GRANT);
+
+                if ($stored["expires"] > time())
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_GRANT);
+
+                break;
+            case NONE_GRANT_TYPE:
+                $stored = $this->check_none_access($client[0]);
+
+                if ($stored === false)
+                    $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+        }
+
+        // Check scope, if provided
+        if ($input["scope"] && (!is_array($stored) || !isset($stored["scope"]) || !$this->check_scope($input["scope"], $stored["scope"])))
+            $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_SCOPE);
+
+        if (!$input["scope"])
+            $input["scope"] = null;
+
+        $token = $this->create_access_token($client[0], $input["scope"]);
+
+        $this->send_json_headers();
+        echo json_encode($token);
+    }
+
+    // Internal function used to get the client credentials from HTTP basic auth or POST data
+    // See http://tools.ietf.org/html/draft-ietf-oauth-v2-08#section-2
+    private function get_client_credentials() {
+        if (isset($_SERVER["PHP_AUTH_USER"]) && $_POST && isset($_POST["client_id"]))
+            $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_CLIENT_CREDENTIALS);
+
+        // Try basic auth
+        if (isset($_SERVER["PHP_AUTH_USER"]))
+            return array($_SERVER["PHP_AUTH_USER"], $_SERVER["PHP_AUTH_PW"]);
+
+        // Try POST
+        if ($_POST && isset($_POST["client_id"])) {
+            if (isset($_POST["client_secret"]))
+                return array($_POST["client_id"], $_POST["client_secret"]);
+
+            return array($_POST["client_id"], NULL);
+        }
+
+        // No credentials were specified
+        $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_CLIENT_CREDENTIALS);
+    }
+
+    /* End-user/client Authorization (Section 3 of IETF Draft) */
+
+    // Pull the authorization request data out of the HTTP request
+    // and return it so the authorization server can prompt the user
+    // for approval
+    public function get_authorize_params() {
+        $filters = array(
+            "client_id" => array("filter" => FILTER_VALIDATE_REGEXP, "options" => array("regexp" => REGEX_CLIENT_ID), "flags" => FILTER_REQUIRE_SCALAR),
+            "response_type" => array("filter" => FILTER_VALIDATE_REGEXP, "options" => array("regexp" => REGEX_AUTH_RESPONSE_TYPE), "flags" => FILTER_REQUIRE_SCALAR),
+            "redirect_uri" => array("filter" => FILTER_VALIDATE_URL, "flags" => array(FILTER_FLAG_SCHEME_REQUIRED, FILTER_REQUIRE_SCALAR)),
+            "state" => array("flags" => FILTER_REQUIRE_SCALAR),
+            "scope" => array("flags" => FILTER_REQUIRE_SCALAR),
+        );
+
+        $input = filter_input_array(INPUT_GET, $filters);
+
+        // Make sure a valid client id was supplied
+        if (!$input["client_id"]) {
+            if ($input["redirect_uri"])
+                $this->callback_error($input["redirect_uri"], ERROR_INVALID_CLIENT_ID, $input["state"]);
+
+            $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_CLIENT_ID); // We don't have a good URI to use
+        }
+
+        // redirect_uri is not required if already established via other channels
+        // check an existing redirect URI against the one supplied
+        $redirect_uri = $this->get_redirect_uri($input["client_id"]);
+
+        // At least one of: existing redirect URI or input redirect URI must be specified
+        if (!$redirect_uri && !$input["redirect_uri"])
+            $this->error(ERROR_BAD_REQUEST, ERROR_INVALID_REQUEST);
+
+        // get_redirect_uri should return false if the given client ID is invalid
+        // this probably saves us from making a separate db call, and simplifies the method set
+        if ($redirect_uri === false)
+            $this->callback_error($input["redirect_uri"], ERROR_INVALID_CLIENT_ID, $input["state"]);
+
+        // If there's an existing uri and one from input, verify that they match
+        if ($redirect_uri && $input["redirect_uri"]) {
+            // Ensure that the input uri starts with the stored uri
+            if (strcasecmp(substr($input["redirect_uri"], 0, strlen($redirect_uri)),$redirect_uri) !== 0)
+                $this->callback_error($input["redirect_uri"], ERROR_REDIRECT_URI_MISMATCH, $input["state"]);
+        } elseif ($redirect_uri) { // They did not provide a uri from input, so use the stored one
+            $input["redirect_uri"] = $redirect_uri;
+        }
+
+        // type and client_id are required
+        if (!$input["response_type"])
+            $this->callback_error($input["redirect_uri"], ERROR_INVALID_REQUEST, $input["state"], ERROR_INVALID_RESPONSE_TYPE);
+
+        // Check requested auth response type against the list of supported types
+        if (array_search($input["response_type"], $this->get_supported_auth_response_types()) === false)
+            $this->callback_error($input["redirect_uri"], ERROR_UNSUPPORTED_RESPONSE_TYPE, $input["state"]);
+
+        // Validate that the requested scope is supported
+        if ($input["scope"] && !$this->check_scope($input["scope"], $this->get_supported_scopes()))
+            $this->callback_error($input["redirect_uri"], ERROR_INVALID_SCOPE, $input["state"]);
+
+        return $input;
+    }
+
+    // After the user has approved or denied the access request
+    // the authorization server should call this function to redirect
+    // the user appropriately
+
+    // The params all come from the results of get_authorize_params
+    // except for $is_authorized -- this is true or false depending on whether
+    // the user authorized the access
+    public function finish_client_authorization($is_authorized, $type, $client_id, $redirect_uri, $state, $scope = null) {
+        if ($state !== null)
+            $result["query"]["state"] = $state;
+
+        if ($is_authorized === false) {
+            $result["query"]["error"] = ERROR_USER_DENIED;
+        } else {
+            if ($type == AUTH_CODE_AUTH_RESPONSE_TYPE || $type == CODE_AND_TOKEN_AUTH_RESPONSE_TYPE)
+                $result["query"]["code"] = $this->create_auth_code($client_id, $redirect_uri, $scope);
+
+            if ($type == ACCESS_TOKEN_AUTH_RESPONSE_TYPE || $type == CODE_AND_TOKEN_AUTH_RESPONSE_TYPE)
+                $result["fragment"] = $this->create_access_token($client_id, $scope);
+        }
+
+        $this->do_redirect_uri_callback($redirect_uri, $result);
+    }
+
+    /* Other/utility functions */
+
+    private function do_redirect_uri_callback($redirect_uri, $result) {
+        header("HTTP/1.1 302 Found");
+        header("Location: " . $this->build_uri($redirect_uri, $result));
+        exit;
+    }
+
+    private function build_uri($uri, $data) {
+        $parse_url = parse_url($uri);
+
+        // Add our data to the parsed uri
+        foreach ($data as $k => $v) {
+            if (isset($parse_url[$k]))
+                $parse_url[$k] .= "&" . http_build_query($v);
+            else
+                $parse_url[$k] = http_build_query($v);
+        }
+
+        // Put humpty dumpty back together
+        return
+             ((isset($parse_url["scheme"])) ? $parse_url["scheme"] . "://" : "")
+            .((isset($parse_url["user"])) ? $parse_url["user"] . ((isset($parse_url["pass"])) ? ":" . $parse_url["pass"] : "") ."@" : "")
+            .((isset($parse_url["host"])) ? $parse_url["host"] : "")
+            .((isset($parse_url["port"])) ? ":" . $parse_url["port"] : "")
+            .((isset($parse_url["path"])) ? $parse_url["path"] : "")
+            .((isset($parse_url["query"])) ? "?" . $parse_url["query"] : "")
+            .((isset($parse_url["fragment"])) ? "#" . $parse_url["fragment"] : "");
+    }
+
+    // This belongs in a separate factory, but to keep it simple, I'm just keeping it here.
+    private function create_access_token($client_id, $scope) {
+        $token = array(
+            "access_token" => $this->gen_access_token(),
+            "expires_in" => $this->access_token_lifetime,
+            "scope" => $scope
+        );
+
+        $this->store_access_token($token["access_token"], $client_id, time() + $this->access_token_lifetime, $scope);
+
+        // Issue a refresh token also, if we support them
+        if (in_array(REFRESH_TOKEN_GRANT_TYPE, $this->get_supported_grant_types())) {
+            $token["refresh_token"] = $this->gen_access_token();
+            $this->store_refresh_token($token["refresh_token"], $client_id, time() + $this->refresh_token_lifetime, $scope);
+        }
+
+        return $token;
+    }
+
+    private function create_auth_code($client_id, $redirect_uri, $scope) {
+        $code = $this->gen_auth_code();
+        $this->store_auth_code($code, $client_id, $redirect_uri, time() + $this->auth_code_lifetime, $scope);
+        return $code;
+    }
+
+    // Implementing classes may want to override these two functions
+    // to implement other access token or auth code generation schemes
+    private function gen_access_token() {
+        return base64_encode(pack('N6', mt_rand(), mt_rand(), mt_rand(), mt_rand(), mt_rand(), mt_rand()));
+    }
+
+    private function gen_auth_code() {
+        return base64_encode(pack('N6', mt_rand(), mt_rand(), mt_rand(), mt_rand(), mt_rand(), mt_rand()));
+    }
+
+    // Implementing classes may need to override this function for use on non-Apache web servers
+    // Just pull out the Authorization HTTP header and return it
+    // Return false if the Authorization header does not exist
+    private function get_authorization_header() {
+        if (array_key_exists("HTTP_AUTHORIZATION", $_SERVER))
+            return $_SERVER["HTTP_AUTHORIZATION"];
+
+        if (function_exists("apache_request_headers")) {
+            $headers = apache_request_headers();
+
+            if (array_key_exists("Authorization", $headers))
+                return $headers["Authorization"];
+        }
+
+        return false;
+    }
+
+    private function send_json_headers() {
+        header("Content-Type: application/json");
+        header("Cache-Control: no-store");
+    }
+
+    public function error($code, $message = null) {
+        header("HTTP/1.1 " . $code);
+
+        if ($message) {
+            $this->send_json_headers();
+            echo json_encode(array("error" => $message));
+        }
+
+        exit;
+    }
+
+    public function callback_error($redirect_uri, $error, $state, $message = null, $error_uri = null) {
+        $result["query"]["error"] = $error;
+
+        if ($state)
+            $result["query"]["state"] = $state;
+
+        if ($message)
+            $result["query"]["error_description"] = $message;
+
+        if ($error_uri)
+            $result["query"]["error_uri"] = $error_uri;
+
+        $this->do_redirect_uri_callback($redirect_uri, $result);
+    }
+}
\ No newline at end of file