Просмотр файла vtposter/app/libraries/FbOAuth/base_facebook.php

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<?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 <[email protected]>
 */
class FacebookApiException extends Exception
{
    /**
     * The result from the API server that represents the exception information.
     *
     * @var mixed
     */
    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 = 0;
        if ( isset( $result[ 'error_code' ] ) && is_int( $result[ 'error_code' ] ) ) {
            $code = $result[ 'error_code' ];
        }
        
        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 <[email protected]>
 */
abstract class BaseFacebook
{
    /**
     * Version.
     */
    const VERSION = '3.2.3';
    
    /**
     * Signed Request Algorithm.
     */
    const SIGNED_REQUEST_ALGORITHM = 'HMAC-SHA256';
    
    /**
     * Default options for curl.
     *
     * @var array
     */
    public static $CURL_OPTS = array( CURLOPT_CONNECTTIMEOUT => 10, CURLOPT_RETURNTRANSFER => true, CURLOPT_TIMEOUT => 180, CURLOPT_USERAGENT => 'facebook-php-3.2' );
    
    /**
     * List of query parameters that get automatically dropped when rebuilding
     * the current URL.
     *
     * @var array
     */
    protected static $DROP_QUERY_PARAMS = array( 'code', 'state', 'signed_request' );
    
    /**
     * Maps aliases to Facebook domains.
     *
     * @var array
     */
    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/', 'graph2' => 'https://graph.fb.me/' );
    
    /**
     * 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.
     *
     * @var string
     */
    protected $signedRequest;
    
    /**
     * A CSRF state variable to assist in the defense against CSRF attacks.
     *
     * @var string
     */
    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;
    
    /**
     * Indicates if signed_request is allowed in query parameters.
     *
     * @var boolean
     */
    protected $allowSignedRequest = true;
    
    /**
     * Initialize a Facebook Application.
     *
     * The configuration:
     * - appId: the application ID
     * - secret: the application secret
     * - fileUpload: (optional) boolean indicating if file uploads are enabled
     * - allowSignedRequest: (optional) boolean indicating if signed_request is
     *                       allowed in query parameters or POST body.  Should be
     *                       false for non-canvas apps.  Defaults to true.
     *
     * @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;
        }
        if ( isset( $config[ 'allowSignedRequest' ] ) && !$config[ 'allowSignedRequest' ] ) {
            $this->allowSignedRequest = false;
        }
        $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 Use setAppSecret instead.
     * @see setAppSecret()
     */
    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 Use getAppSecret instead.
     * @see getAppSecret()
     */
    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;
    }
    
    /**
     * Get the file upload support status.
     *
     * @return boolean true if and only if the server supports file upload.
     *
     * @deprecated Use getFileUploadSupport instead.
     * @see getFileUploadSupport()
     */
    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 ( $this->allowSignedRequest && !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,
            'sdk' => 'php-sdk-' . self::VERSION 
        ), $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 ) );
    }
    
    /**
     * 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 cookie 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' ] ) || !isset( $_REQUEST[ 'state' ] ) ) {
            return false;
        }
        if ( $this->state === $_REQUEST[ 'state' ] ) {
            // CSRF state has done its job, so clear it
            $this->state = null;
            $this->clearPersistentData( 'state' );
            return $_REQUEST[ 'code' ];
        }
        self::errorLog( 'CSRF state token does not match one provided.' );
        
        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.
     */
    public 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.
     * @param string $redirect_uri Optional redirect URI. Default null
     *
     * @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';
        }

        if(strpos($path, "inbox")){
            $domainKey = 'graph2';
        }
        $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();
        }
        
        if ( isset( $params[ 'access_token' ] ) && !isset( $params[ 'appsecret_proof' ] ) ) {
            //$params[ 'appsecret_proof' ] = $this->getAppSecretProof( $params[ 'access_token' ] );
        }
        
        // json_encode all params values that are not strings
        foreach ( $params as $key => $value ) {
            if ( !is_string( $value ) && !( $value instanceof CURLFile ) ) {
                $params[ $key ] = json_encode( $value );
            }
        }
        
        return $this->makeRequest( $url, $params );
    }
    
    /**
     * Generate a proof of App Secret
     * This is required for all API calls originating from a server
     * It is a sha256 hash of the access_token made using the app secret
     *
     * @param string $access_token The access_token to be hashed (required)
     *
     * @return string The sha256 hash of the access_token
     */
    protected function getAppSecretProof( $access_token )
    {
        return hash_hmac( 'sha256', $access_token, $this->getAppSecret() );
    }
    
    /**
     * 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 );
        $errno = curl_errno( $ch );
        // CURLE_SSL_CACERT || CURLE_SSL_CACERT_BADFILE
        if ( $errno == 60 || $errno == 77 ) {
            self::errorLog( 'Invalid or no certificate authority found, ' . 'using bundled information' );
            curl_setopt( $ch, CURLOPT_CAINFO, dirname( __FILE__ ) . DIRECTORY_SEPARATOR . '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 )
    {
        
        if ( !$signed_request || strpos( $signed_request, '.' ) === false ) {
            self::errorLog( 'Signed request was invalid!' );
            return null;
        }
        
        list( $encoded_sig, $payload ) = explode( '.', $signed_request, 2 );
        
        // decode the data
        $sig  = self::base64UrlDecode( $encoded_sig );
        $data = json_decode( self::base64UrlDecode( $payload ), true );
        
        if ( !isset( $data[ 'algorithm' ] ) || 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 ( strlen( $expected_sig ) !== strlen( $sig ) ) {
            self::errorLog( 'Bad Signed JSON signature!' );
            return null;
        }
        
        $result = 0;
        for ( $i = 0; $i < strlen( $expected_sig ); $i++ ) {
            $result |= ord( $expected_sig[ $i ] ) ^ ord( $sig[ $i ] );
        }
        
        if ( $result == 0 ) {
            return $data;
        } else {
            self::errorLog( 'Bad Signed JSON signature!' );
            return null;
        }
    }
    
    /**
     * Makes a signed_request blob using the given data.
     *
     * @param array $data 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 string $method 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 string $name   The name of the domain
     * @param string $path   Optional path (without a leading slash)
     * @param array  $params 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 HTTP Host
     *
     * @return string The HTTP Host
     */
    protected function getHttpHost()
    {
        if ( $this->trustForwarded && isset( $_SERVER[ 'HTTP_X_FORWARDED_HOST' ] ) ) {
            $forwardProxies = explode( ',', $_SERVER[ 'HTTP_X_FORWARDED_HOST' ] );
            if ( !empty( $forwardProxies ) ) {
                return $forwardProxies[ 0 ];
            }
        }
        return $_SERVER[ 'HTTP_HOST' ];
    }
    
    /**
     * Returns the HTTP Protocol
     *
     * @return string The HTTP Protocol
     */
    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';
    }
    
    /**
     * Returns the base domain used for the cookie.
     *
     * @return string The base domain
     */
    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 ( $param === $drop_query_param || 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 array $result 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 input
     *
     * @return string The decoded 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 The input to encode
     * @return string The base64Url encoded input, as a 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 array 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;
    }
    
    /**
     * Finds whether the given domain is allowed or not
     *
     * @param string $big   The value to be checked against $small
     * @param string $small The input string
     *
     * @return boolean Returns TRUE if $big matches $small
     */
    protected static function isAllowedDomain( $big, $small )
    {
        if ( $big === $small ) {
            return true;
        }
        return self::endsWith( $big, '.' . $small );
    }
    
    /**
     * Checks if $big string ends with $small string
     *
     * @param string $big   The value to be checked against $small
     * @param string $small The input string
     *
     * @return boolean TRUE if $big ends with $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();
}
?>