File indexing completed on 2024-04-28 05:58:49

 <?php
 /**
  * Copyright 2011 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may
  * not use this file except in compliance with the License. You may obtain
  * a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations
  * under the License.
  */
 
 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.
    *
    * @return 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.
    *
    * @return 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.  This class provides
  * a majority of the functionality needed, but the class is abstract
  * because it is designed to be sub-classed.  The subclass must
  * implement the four abstract methods listed at the bottom of
  * the file.
  *
  * @author Naitik Shah <naitik@facebook.com>
  */
 abstract class BaseFacebook
 {
   /**
    * Version.
    */
   const VERSION = '3.2.2';
 
   /**
    * Signed Request Algorithm.
    */
   const SIGNED_REQUEST_ALGORITHM = 'HMAC-SHA256';
 
   /**
    * Default options for curl.
    */
   public static $CURL_OPTS = array(
     CURLOPT_CONNECTTIMEOUT => 10,
     CURLOPT_RETURNTRANSFER => true,
     CURLOPT_TIMEOUT        => 60,
     CURLOPT_USERAGENT      => 'facebook-php-3.2',
   );
 
   /**
    * List of query parameters that get automatically dropped when rebuilding
    * the current URL.
    */
   protected static $DROP_QUERY_PARAMS = array(
     'code',
     'state',
     'signed_request',
   );
 
   /**
    * Maps aliases to Facebook domains.
    */
   public static $DOMAIN_MAP = array(
     'api'         => 'https://api.facebook.com/',
     'api_video'   => 'https://api-video.facebook.com/',
     'api_read'    => 'https://api-read.facebook.com/',
     'graph'       => 'https://graph.facebook.com/',
     'graph_video' => 'https://graph-video.facebook.com/',
     'www'         => 'https://www.facebook.com/',
   );
 
   /**
    * The Application ID.
    *
    * @var string
    */
   protected $appId;
 
   /**
    * The Application App Secret.
    *
    * @var string
    */
   protected $appSecret;
 
   /**
    * The ID of the Facebook user, or 0 if the user is logged out.
    *
    * @var integer
    */
   protected $user;
 
   /**
    * The data from the signed_request token.
    */
   protected $signedRequest;
 
   /**
    * A CSRF state variable to assist in the defense against CSRF attacks.
    */
   protected $state;
 
   /**
    * The OAuth access token received in exchange for a valid authorization
    * code.  null means the access token has yet to be determined.
    *
    * @var string
    */
   protected $accessToken = null;
 
   /**
    * Indicates if the CURL based @ syntax for file uploads is enabled.
    *
    * @var boolean
    */
   protected $fileUploadSupport = false;
 
   /**
    * Indicates if we trust HTTP_X_FORWARDED_* headers.
    *
    * @var boolean
    */
   protected $trustForwarded = false;
 
   /**
    * Initialize a Facebook Application.
    *
    * The configuration:
    * - appId: the application ID
    * - secret: the application secret
    * - fileUpload: (optional) boolean indicating if file uploads are enabled
    *
    * @param array $config The application configuration
    */
   public function __construct($config) {
     $this->setAppId($config['appId']);
     $this->setAppSecret($config['secret']);
     if (isset($config['fileUpload'])) {
       $this->setFileUploadSupport($config['fileUpload']);
     }
     if (isset($config['trustForwarded']) && $config['trustForwarded']) {
       $this->trustForwarded = true;
     }
     $state = $this->getPersistentData('state');
     if (!empty($state)) {
       $this->state = $state;
     }
   }
 
   /**
    * Set the Application ID.
    *
    * @param string $appId The Application ID
    * @return BaseFacebook
    */
   public function setAppId($appId) {
     $this->appId = $appId;
     return $this;
   }
 
   /**
    * Get the Application ID.
    *
    * @return string the Application ID
    */
   public function getAppId() {
     return $this->appId;
   }
 
   /**
    * Set the App Secret.
    *
    * @param string $apiSecret The App Secret
    * @return BaseFacebook
    * @deprecated
    */
   public function setApiSecret($apiSecret) {
     $this->setAppSecret($apiSecret);
     return $this;
   }
 
   /**
    * Set the App Secret.
    *
    * @param string $appSecret The App Secret
    * @return BaseFacebook
    */
   public function setAppSecret($appSecret) {
     $this->appSecret = $appSecret;
     return $this;
   }
 
   /**
    * Get the App Secret.
    *
    * @return string the App Secret
    * @deprecated
    */
   public function getApiSecret() {
     return $this->getAppSecret();
   }
 
   /**
    * Get the App Secret.
    *
    * @return string the App Secret
    */
   public function getAppSecret() {
     return $this->appSecret;
   }
 
   /**
    * Set the file upload support status.
    *
    * @param boolean $fileUploadSupport The file upload support status.
    * @return BaseFacebook
    */
   public function setFileUploadSupport($fileUploadSupport) {
     $this->fileUploadSupport = $fileUploadSupport;
     return $this;
   }
 
   /**
    * Get the file upload support status.
    *
    * @return boolean true if and only if the server supports file upload.
    */
   public function getFileUploadSupport() {
     return $this->fileUploadSupport;
   }
 
   /**
    * DEPRECATED! Please use getFileUploadSupport instead.
    *
    * Get the file upload support status.
    *
    * @return boolean true if and only if the server supports file upload.
    */
   public function useFileUploadSupport() {
     return $this->getFileUploadSupport();
   }
 
   /**
    * Sets the access token for api calls.  Use this if you get
    * your access token by other means and just want the SDK
    * to use it.
    *
    * @param string $access_token an access token.
    * @return BaseFacebook
    */
   public function setAccessToken($access_token) {
     $this->accessToken = $access_token;
     return $this;
   }
 
   /**
    * Extend an access token, while removing the short-lived token that might
    * have been generated via client-side flow. Thanks to http://bit.ly/b0Pt0H
    * for the workaround.
    */
   public function setExtendedAccessToken() {
     try {
       // need to circumvent json_decode by calling _oauthRequest
       // directly, since response isn't JSON format.
       $access_token_response = $this->_oauthRequest(
         $this->getUrl('graph', '/oauth/access_token'),
         $params = array(
           'client_id' => $this->getAppId(),
           'client_secret' => $this->getAppSecret(),
           'grant_type' => 'fb_exchange_token',
           'fb_exchange_token' => $this->getAccessToken(),
         )
       );
     }
     catch (FacebookApiException $e) {
       // most likely that user very recently revoked authorization.
       // In any event, we don't have an access token, so say so.
       return false;
     }
 
     if (empty($access_token_response)) {
       return false;
     }
 
     $response_params = array();
     parse_str($access_token_response, $response_params);
 
     if (!isset($response_params['access_token'])) {
       return false;
     }
 
     $this->destroySession();
 
     $this->setPersistentData(
       'access_token', $response_params['access_token']
     );
   }
 
   /**
    * Determines the access token that should be used for API calls.
    * The first time this is called, $this->accessToken is set equal
    * to either a valid user access token, or it's set to the application
    * access token if a valid user access token wasn't available.  Subsequent
    * calls return whatever the first call returned.
    *
    * @return string The access token
    */
   public function getAccessToken() {
     if ($this->accessToken !== null) {
       // we've done this already and cached it.  Just return.
       return $this->accessToken;
     }
 
     // first establish access token to be the application
     // access token, in case we navigate to the /oauth/access_token
     // endpoint, where SOME access token is required.
     $this->setAccessToken($this->getApplicationAccessToken());
     $user_access_token = $this->getUserAccessToken();
     if ($user_access_token) {
       $this->setAccessToken($user_access_token);
     }
 
     return $this->accessToken;
   }
 
   /**
    * Determines and returns the user access token, first using
    * the signed request if present, and then falling back on
    * the authorization code if present.  The intent is to
    * return a valid user access token, or false if one is determined
    * to not be available.
    *
    * @return string A valid user access token, or false if one
    *                could not be determined.
    */
   protected function getUserAccessToken() {
     // first, consider a signed request if it's supplied.
     // if there is a signed request, then it alone determines
     // the access token.
     $signed_request = $this->getSignedRequest();
     if ($signed_request) {
       // apps.facebook.com hands the access_token in the signed_request
       if (array_key_exists('oauth_token', $signed_request)) {
         $access_token = $signed_request['oauth_token'];
         $this->setPersistentData('access_token', $access_token);
         return $access_token;
       }
 
       // the JS SDK puts a code in with the redirect_uri of ''
       if (array_key_exists('code', $signed_request)) {
         $code = $signed_request['code'];
         if ($code && $code == $this->getPersistentData('code')) {
           // short-circuit if the code we have is the same as the one presented
           return $this->getPersistentData('access_token');
         }
 
         $access_token = $this->getAccessTokenFromCode($code, '');
         if ($access_token) {
           $this->setPersistentData('code', $code);
           $this->setPersistentData('access_token', $access_token);
           return $access_token;
         }
       }
 
       // signed request states there's no access token, so anything
       // stored should be cleared.
       $this->clearAllPersistentData();
       return false; // respect the signed request's data, even
                     // if there's an authorization code or something else
     }
 
     $code = $this->getCode();
     if ($code && $code != $this->getPersistentData('code')) {
       $access_token = $this->getAccessTokenFromCode($code);
       if ($access_token) {
         $this->setPersistentData('code', $code);
         $this->setPersistentData('access_token', $access_token);
         return $access_token;
       }
 
       // code was bogus, so everything based on it should be invalidated.
       $this->clearAllPersistentData();
       return false;
     }
 
     // as a fallback, just return whatever is in the persistent
     // store, knowing nothing explicit (signed request, authorization
     // code, etc.) was present to shadow it (or we saw a code in $_REQUEST,
     // but it's the same as what's in the persistent store)
     return $this->getPersistentData('access_token');
   }
 
   /**
    * Retrieve the signed request, either from a request parameter or,
    * if not present, from a cookie.
    *
    * @return string the signed request, if available, or null otherwise.
    */
   public function getSignedRequest() {
     if (!$this->signedRequest) {
       if (!empty($_REQUEST['signed_request'])) {
         $this->signedRequest = $this->parseSignedRequest(
           $_REQUEST['signed_request']);
       } else if (!empty($_COOKIE[$this->getSignedRequestCookieName()])) {
         $this->signedRequest = $this->parseSignedRequest(
           $_COOKIE[$this->getSignedRequestCookieName()]);
       }
     }
     return $this->signedRequest;
   }
 
   /**
    * Get the UID of the connected user, or 0
    * if the Facebook user is not connected.
    *
    * @return string the UID if available.
    */
   public function getUser() {
     if ($this->user !== null) {
       // we've already determined this and cached the value.
       return $this->user;
     }
 
     return $this->user = $this->getUserFromAvailableData();
   }
 
   /**
    * Determines the connected user by first examining any signed
    * requests, then considering an authorization code, and then
    * falling back to any persistent store storing the user.
    *
    * @return integer The id of the connected Facebook user,
    *                 or 0 if no such user exists.
    */
   protected function getUserFromAvailableData() {
     // if a signed request is supplied, then it solely determines
     // who the user is.
     $signed_request = $this->getSignedRequest();
     if ($signed_request) {
       if (array_key_exists('user_id', $signed_request)) {
         $user = $signed_request['user_id'];
 
         if($user != $this->getPersistentData('user_id')){
           $this->clearAllPersistentData();
         }
 
         $this->setPersistentData('user_id', $signed_request['user_id']);
         return $user;
       }
 
       // if the signed request didn't present a user id, then invalidate
       // all entries in any persistent store.
       $this->clearAllPersistentData();
       return 0;
     }
 
     $user = $this->getPersistentData('user_id', $default = 0);
     $persisted_access_token = $this->getPersistentData('access_token');
 
     // use access_token to fetch user id if we have a user access_token, or if
     // the cached access token has changed.
     $access_token = $this->getAccessToken();
     if ($access_token &&
         $access_token != $this->getApplicationAccessToken() &&
         !($user && $persisted_access_token == $access_token)) {
       $user = $this->getUserFromAccessToken();
       if ($user) {
         $this->setPersistentData('user_id', $user);
       } else {
         $this->clearAllPersistentData();
       }
     }
 
     return $user;
   }
 
   /**
    * 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:
    * - redirect_uri: the url to go to after a successful login
    * - scope: comma separated list of requested extended perms
    *
    * @param array $params Provide custom parameters
    * @return string The URL for the login flow
    */
   public function getLoginUrl($params=array()) {
     $this->establishCSRFTokenState();
     $currentUrl = $this->getCurrentUrl();
 
     // if 'scope' is passed as an array, convert to comma separated list
     $scopeParams = isset($params['scope']) ? $params['scope'] : null;
     if ($scopeParams && is_array($scopeParams)) {
       $params['scope'] = implode(',', $scopeParams);
     }
 
     return $this->getUrl(
       'www',
       'dialog/oauth',
       array_merge(array(
                     'client_id' => $this->getAppId(),
                     'redirect_uri' => $currentUrl, // possibly overwritten
                     'state' => $this->state),
                   $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->getUserAccessToken(),
       ), $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.
    *
    * @return mixed 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);
     }
   }
 
   /**
    * Constructs and returns the name of the cookie that
    * potentially houses the signed request for the app user.
    * The cookie is not set by the BaseFacebook class, but
    * it may be set by the JavaScript SDK.
    *
    * @return string the name of the cookie that would house
    *         the signed request value.
    */
   protected function getSignedRequestCookieName() {
     return 'fbsr_'.$this->getAppId();
   }
 
   /**
    * Constructs and returns the name of the coookie that potentially contain
    * metadata. The cookie is not set by the BaseFacebook class, but it may be
    * set by the JavaScript SDK.
    *
    * @return string the name of the cookie that would house metadata.
    */
   protected function getMetadataCookieName() {
     return 'fbm_'.$this->getAppId();
   }
 
   /**
    * Get the authorization code from the query parameters, if it exists,
    * and otherwise return false to signal no authorization code was
    * discoverable.
    *
    * @return mixed The authorization code, or false if the authorization
    *               code could not be determined.
    */
   protected function getCode() {
     if (isset($_REQUEST['code'])) {
       if ($this->state !== null &&
           isset($_REQUEST['state']) &&
           $this->state === $_REQUEST['state']) {
 
         // CSRF state has done its job, so clear it
         $this->state = null;
         $this->clearPersistentData('state');
         return $_REQUEST['code'];
       } else {
         self::errorLog('CSRF state token does not match one provided.');
         return false;
       }
     }
 
     return false;
   }
 
   /**
    * Retrieves the UID with the understanding that
    * $this->accessToken has already been set and is
    * seemingly legitimate.  It relies on Facebook's Graph API
    * to retrieve user information and then extract
    * the user ID.
    *
    * @return integer Returns the UID of the Facebook user, or 0
    *                 if the Facebook user could not be determined.
    */
   protected function getUserFromAccessToken() {
     try {
       $user_info = $this->api('/me');
       return $user_info['id'];
     } catch (FacebookApiException $e) {
       return 0;
     }
   }
 
   /**
    * Returns the access token that should be used for logged out
    * users when no authorization code is available.
    *
    * @return string The application access token, useful for gathering
    *                public information about users and applications.
    */
   protected function getApplicationAccessToken() {
     return $this->appId.'|'.$this->appSecret;
   }
 
   /**
    * Lays down a CSRF state token for this process.
    *
    * @return void
    */
   protected function establishCSRFTokenState() {
     if ($this->state === null) {
       $this->state = md5(uniqid(mt_rand(), true));
       $this->setPersistentData('state', $this->state);
     }
   }
 
   /**
    * Retrieves an access token for the given authorization code
    * (previously generated from www.facebook.com on behalf of
    * a specific user).  The authorization code is sent to graph.facebook.com
    * and a legitimate access token is generated provided the access token
    * and the user for which it was generated all match, and the user is
    * either logged in to Facebook or has granted an offline access permission.
    *
    * @param string $code An authorization code.
    * @return mixed An access token exchanged for the authorization code, or
    *               false if an access token could not be generated.
    */
   protected function getAccessTokenFromCode($code, $redirect_uri = null) {
     if (empty($code)) {
       return false;
     }
 
     if ($redirect_uri === null) {
       $redirect_uri = $this->getCurrentUrl();
     }
 
     try {
       // need to circumvent json_decode by calling _oauthRequest
       // directly, since response isn't JSON format.
       $access_token_response =
         $this->_oauthRequest(
           $this->getUrl('graph', '/oauth/access_token'),
           $params = array('client_id' => $this->getAppId(),
                           'client_secret' => $this->getAppSecret(),
                           'redirect_uri' => $redirect_uri,
                           'code' => $code));
     } catch (FacebookApiException $e) {
       // most likely that user very recently revoked authorization.
       // In any event, we don't have an access token, so say so.
       return false;
     }
 
     if (empty($access_token_response)) {
       return false;
     }
 
     $response_params = array();
     parse_str($access_token_response, $response_params);
     if (!isset($response_params['access_token'])) {
       return false;
     }
 
     return $response_params['access_token'];
   }
 
   /**
    * Invoke the old restserver.php endpoint.
    *
    * @param array $params Method call object
    *
    * @return mixed The decoded response object
    * @throws FacebookApiException
    */
   protected function _restserver($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'])) {
       $this->throwAPIException($result);
       // @codeCoverageIgnoreStart
     }
     // @codeCoverageIgnoreEnd
 
     $method = strtolower($params['method']);
     if ($method === 'auth.expiresession' ||
         $method === 'auth.revokeauthorization') {
       $this->destroySession();
     }
 
     return $result;
   }
 
   /**
    * Return true if this is video post.
    *
    * @param string $path The path
    * @param string $method The http method (default 'GET')
    *
    * @return boolean true if this is video post
    */
   protected function isVideoPost($path, $method = 'GET') {
     if ($method == 'POST' && preg_match("/^(\/)(.+)(\/)(videos)$/", $path)) {
       return true;
     }
     return false;
   }
 
   /**
    * Invoke the Graph API.
    *
    * @param string $path The path (required)
    * @param string $method The http method (default 'GET')
    * @param array $params The query/post data
    *
    * @return mixed The decoded response object
    * @throws FacebookApiException
    */
   protected function _graph($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
 
     if ($this->isVideoPost($path, $method)) {
       $domainKey = 'graph_video';
     } else {
       $domainKey = 'graph';
     }
 
     $result = json_decode($this->_oauthRequest(
       $this->getUrl($domainKey, $path),
       $params
     ), true);
 
     // results are returned, errors are thrown
     if (is_array($result) && isset($result['error'])) {
       $this->throwAPIException($result);
       // @codeCoverageIgnoreStart
     }
     // @codeCoverageIgnoreEnd
 
     return $result;
   }
 
   /**
    * Make a OAuth Request.
    *
    * @param string $url The path (required)
    * @param array $params The query/post data
    *
    * @return string The decoded response object
    * @throws FacebookApiException
    */
   protected function _oauthRequest($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 overridden 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 $ch Initialized curl handle
    *
    * @return string The response text
    */
   protected function makeRequest($url, $params, $ch=null) {
     if (!$ch) {
       $ch = curl_init();
     }
 
     $opts = self::$CURL_OPTS;
     if ($this->getFileUploadSupport()) {
       $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 (curl_errno($ch) == 60) { // CURLE_SSL_CACERT
       self::errorLog('Invalid or no certificate authority found, '.
                      'using bundled information');
       curl_setopt($ch, CURLOPT_CAINFO,
                   dirname(__FILE__) . '/fb_ca_chain_bundle.crt');
       $result = curl_exec($ch);
     }
 
     // With dual stacked DNS responses, it's possible for a server to
     // have IPv6 enabled but not have IPv6 connectivity.  If this is
     // the case, curl will try IPv4 first and if that fails, then it will
     // fall back to IPv6 and the error EHOSTUNREACH is returned by the
     // operating system.
     if ($result === false && empty($opts[CURLOPT_IPRESOLVE])) {
         $matches = array();
         $regex = '/Failed to connect to ([^:].*): Network is unreachable/';
         if (preg_match($regex, curl_error($ch), $matches)) {
           if (strlen(@inet_pton($matches[1])) === 16) {
             self::errorLog('Invalid IPv6 configuration on server, '.
                            'Please disable or get native IPv6 on your server.');
             self::$CURL_OPTS[CURLOPT_IPRESOLVE] = CURL_IPRESOLVE_V4;
             curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
             $result = curl_exec($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;
   }
 
   /**
    * Parses a signed_request and validates the signature.
    *
    * @param string $signed_request A signed token
    * @return array The payload inside it or null if the sig is wrong
    */
   protected function parseSignedRequest($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']) !== self::SIGNED_REQUEST_ALGORITHM) {
       self::errorLog(
         'Unknown algorithm. Expected ' . self::SIGNED_REQUEST_ALGORITHM);
       return null;
     }
 
     // check sig
     $expected_sig = hash_hmac('sha256', $payload,
                               $this->getAppSecret(), $raw = true);
     if ($sig !== $expected_sig) {
       self::errorLog('Bad Signed JSON signature!');
       return null;
     }
 
     return $data;
   }
 
   /**
    * Makes a signed_request blob using the given data.
    *
    * @param array The data array.
    * @return string The signed request.
    */
   protected function makeSignedRequest($data) {
     if (!is_array($data)) {
       throw new InvalidArgumentException(
         'makeSignedRequest expects an array. Got: ' . print_r($data, true));
     }
     $data['algorithm'] = self::SIGNED_REQUEST_ALGORITHM;
     $data['issued_at'] = time();
     $json = json_encode($data);
     $b64 = self::base64UrlEncode($json);
     $raw_sig = hash_hmac('sha256', $b64, $this->getAppSecret(), $raw = true);
     $sig = self::base64UrlEncode($raw_sig);
     return $sig.'.'.$b64;
   }
 
   /**
    * 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)])) {
       $name = 'api_read';
     } else if (strtolower($method) == 'video.upload') {
       $name = 'api_video';
     }
     return self::getUrl($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;
   }
 
   protected function getHttpHost() {
     if ($this->trustForwarded && isset($_SERVER['HTTP_X_FORWARDED_HOST'])) {
       return $_SERVER['HTTP_X_FORWARDED_HOST'];
     }
     return $_SERVER['HTTP_HOST'];
   }
 
   protected function getHttpProtocol() {
     if ($this->trustForwarded && isset($_SERVER['HTTP_X_FORWARDED_PROTO'])) {
       if ($_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https') {
         return 'https';
       }
       return 'http';
     }
     /*apache + variants specific way of checking for https*/
     if (isset($_SERVER['HTTPS']) &&
         ($_SERVER['HTTPS'] === 'on' || $_SERVER['HTTPS'] == 1)) {
       return 'https';
     }
     /*nginx way of checking for https*/
     if (isset($_SERVER['SERVER_PORT']) &&
         ($_SERVER['SERVER_PORT'] === '443')) {
       return 'https';
     }
     return 'http';
   }
 
   /**
    * Get the base domain used for the cookie.
    */
   protected function getBaseDomain() {
     // The base domain is stored in the metadata cookie if not we fallback
     // to the current hostname
     $metadata = $this->getMetadataCookie();
     if (array_key_exists('base_domain', $metadata) &&
         !empty($metadata['base_domain'])) {
       return trim($metadata['base_domain'], '.');
     }
     return $this->getHttpHost();
   }
 
   /**
 
   /**
    * Returns the Current URL, stripping it of known FB parameters that should
    * not persist.
    *
    * @return string The current URL
    */
   protected function getCurrentUrl() {
     $protocol = $this->getHttpProtocol() . '://';
     $host = $this->getHttpHost();
     $currentUrl = $protocol.$host.$_SERVER['REQUEST_URI'];
     $parts = parse_url($currentUrl);
 
     $query = '';
     if (!empty($parts['query'])) {
       // drop known fb params
       $params = explode('&', $parts['query']);
       $retained_params = array();
       foreach ($params as $param) {
         if ($this->shouldRetainParam($param)) {
           $retained_params[] = $param;
         }
       }
 
       if (!empty($retained_params)) {
         $query = '?'.implode($retained_params, '&');
       }
     }
 
     // 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;
   }
 
   /**
    * Returns true if and only if the key or key/value pair should
    * be retained as part of the query string.  This amounts to
    * a brute-force search of the very small list of Facebook-specific
    * params that should be stripped out.
    *
    * @param string $param A key or key/value pair within a URL's query (e.g.
    *                     'foo=a', 'foo=', or 'foo'.
    *
    * @return boolean
    */
   protected function shouldRetainParam($param) {
     foreach (self::$DROP_QUERY_PARAMS as $drop_query_param) {
       if (strpos($param, $drop_query_param.'=') === 0) {
         return false;
       }
     }
 
     return true;
   }
 
   /**
    * Analyzes the supplied result to see if it was thrown
    * because the access token is no longer valid.  If that is
    * the case, then we destroy the session.
    *
    * @param $result array A record storing the error message returned
    *                      by a failed API call.
    */
   protected function throwAPIException($result) {
     $e = new FacebookApiException($result);
     switch ($e->getType()) {
       // OAuth 2.0 Draft 00 style
       case 'OAuthException':
         // OAuth 2.0 Draft 10 style
       case 'invalid_token':
         // REST server errors are just Exceptions
       case 'Exception':
         $message = $e->getMessage();
         if ((strpos($message, 'Error validating access token') !== false) ||
             (strpos($message, 'Invalid OAuth access token') !== false) ||
             (strpos($message, 'An active access token must be used') !== false)
         ) {
           $this->destroySession();
         }
         break;
     }
 
     throw $e;
   }
 
 
   /**
    * Prints to the error log if you aren't in command line mode.
    *
    * @param string $msg Log message
    */
   protected static function errorLog($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 /
    *   No padded =
    *
    * @param string $input base64UrlEncoded string
    * @return string
    */
   protected static function base64UrlDecode($input) {
     return base64_decode(strtr($input, '-_', '+/'));
   }
 
   /**
    * 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 $input string
    * @return string base64Url encoded string
    */
   protected static function base64UrlEncode($input) {
     $str = strtr(base64_encode($input), '+/', '-_');
     $str = str_replace('=', '', $str);
     return $str;
   }
 
   /**
    * Destroy the current session
    */
   public function destroySession() {
     $this->accessToken = null;
     $this->signedRequest = null;
     $this->user = null;
     $this->clearAllPersistentData();
 
     // Javascript sets a cookie that will be used in getSignedRequest that we
     // need to clear if we can
     $cookie_name = $this->getSignedRequestCookieName();
     if (array_key_exists($cookie_name, $_COOKIE)) {
       unset($_COOKIE[$cookie_name]);
       if (!headers_sent()) {
         $base_domain = $this->getBaseDomain();
         setcookie($cookie_name, '', 1, '/', '.'.$base_domain);
       } else {
         // @codeCoverageIgnoreStart
         self::errorLog(
           'There exists a cookie that we wanted to clear that we couldn\'t '.
           'clear because headers was already sent. Make sure to do the first '.
           'API call before outputing anything.'
         );
         // @codeCoverageIgnoreEnd
       }
     }
   }
 
   /**
    * Parses the metadata cookie that our Javascript API set
    *
    * @return  an array mapping key to value
    */
   protected function getMetadataCookie() {
     $cookie_name = $this->getMetadataCookieName();
     if (!array_key_exists($cookie_name, $_COOKIE)) {
       return array();
     }
 
     // The cookie value can be wrapped in "-characters so remove them
     $cookie_value = trim($_COOKIE[$cookie_name], '"');
 
     if (empty($cookie_value)) {
       return array();
     }
 
     $parts = explode('&', $cookie_value);
     $metadata = array();
     foreach ($parts as $part) {
       $pair = explode('=', $part, 2);
       if (!empty($pair[0])) {
         $metadata[urldecode($pair[0])] =
           (count($pair) > 1) ? urldecode($pair[1]) : '';
       }
     }
 
     return $metadata;
   }
 
   protected static function isAllowedDomain($big, $small) {
     if ($big === $small) {
       return true;
     }
     return self::endsWith($big, '.'.$small);
   }
 
   protected static function endsWith($big, $small) {
     $len = strlen($small);
     if ($len === 0) {
       return true;
     }
     return substr($big, -$len) === $small;
   }
 
   /**
    * Each of the following four methods should be overridden in
    * a concrete subclass, as they are in the provided Facebook class.
    * The Facebook class uses PHP sessions to provide a primitive
    * persistent store, but another subclass--one that you implement--
    * might use a database, memcache, or an in-memory cache.
    *
    * @see Facebook
    */
 
   /**
    * Stores the given ($key, $value) pair, so that future calls to
    * getPersistentData($key) return $value. This call may be in another request.
    *
    * @param string $key
    * @param array $value
    *
    * @return void
    */
   abstract protected function setPersistentData($key, $value);
 
   /**
    * Get the data for $key, persisted by BaseFacebook::setPersistentData()
    *
    * @param string $key The key of the data to retrieve
    * @param boolean $default The default value to return if $key is not found
    *
    * @return mixed
    */
   abstract protected function getPersistentData($key, $default = false);
 
   /**
    * Clear the data with $key from the persistent storage
    *
    * @param string $key
    * @return void
    */
   abstract protected function clearPersistentData($key);
 
   /**
    * Clear all data from the persistent storage
    *
    * @return void
    */
   abstract protected function clearAllPersistentData();
 }