Subversion Repositories cheapmusic

<?php

/*

 * Copyright 2008 Google 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.

 */

require_once "Google_Verifier.php";

require_once "Google_LoginTicket.php";

require_once "service/Google_Utils.php";

/**

 * Authentication class that deals with the OAuth 2 web-server authentication flow

 *

 * @author Chris Chabot <chabotc@google.com>

 * @author Chirag Shah <chirags@google.com>

 *

 */

class Google_OAuth2 extends Google_Auth {

  public $clientId;

  public $clientSecret;

  public $developerKey;

  public $token;

  public $redirectUri;

  public $state;

  public $accessType = 'offline';

  public $approvalPrompt = 'force';

  /** @var Google_AssertionCredentials $assertionCredentials */

  public $assertionCredentials;

  const OAUTH2_REVOKE_URI = 'https://accounts.google.com/o/oauth2/revoke';

  const OAUTH2_TOKEN_URI = 'https://accounts.google.com/o/oauth2/token';

  const OAUTH2_AUTH_URL = 'https://accounts.google.com/o/oauth2/auth';

  const OAUTH2_FEDERATED_SIGNON_CERTS_URL = 'https://www.googleapis.com/oauth2/v1/certs';

  const CLOCK_SKEW_SECS = 300; // five minutes in seconds

  const AUTH_TOKEN_LIFETIME_SECS = 300; // five minutes in seconds

  const MAX_TOKEN_LIFETIME_SECS = 86400; // one day in seconds

  /**

   * Instantiates the class, but does not initiate the login flow, leaving it

   * to the discretion of the caller (which is done by calling authenticate()).

   */

  public function __construct() {

    global $apiConfig;

    if (! empty($apiConfig['developer_key'])) {

      $this->developerKey = $apiConfig['developer_key'];

    }

    if (! empty($apiConfig['oauth2_client_id'])) {

      $this->clientId = $apiConfig['oauth2_client_id'];

    }

    if (! empty($apiConfig['oauth2_client_secret'])) {

      $this->clientSecret = $apiConfig['oauth2_client_secret'];

    }

    if (! empty($apiConfig['oauth2_redirect_uri'])) {

      $this->redirectUri = $apiConfig['oauth2_redirect_uri'];

    }

    if (! empty($apiConfig['oauth2_access_type'])) {

      $this->accessType = $apiConfig['oauth2_access_type'];

    }

    if (! empty($apiConfig['oauth2_approval_prompt'])) {

      $this->approvalPrompt = $apiConfig['oauth2_approval_prompt'];

    }

  }

  /**

   * @param $service

   * @param string|null $code

   * @throws Google_AuthException

   * @return string

   */

  public function authenticate($service, $code = null) {

    if (!$code && isset($_GET['code'])) {

      $code = $_GET['code'];

    }

    if ($code) {

      // We got here from the redirect from a successful authorization grant, fetch the access token

      $request = Google_Client::$io->makeRequest(new Google_HttpRequest(self::OAUTH2_TOKEN_URI, 'POST', array(), array(

          'code' => $code,

          'grant_type' => 'authorization_code',

          'redirect_uri' => $this->redirectUri,

          'client_id' => $this->clientId,

          'client_secret' => $this->clientSecret

      )));

      if ($request->getResponseHttpCode() == 200) {

        $this->setAccessToken($request->getResponseBody());

        $this->token['created'] = time();

        return $this->getAccessToken();

      } else {

        $response = $request->getResponseBody();

        $decodedResponse = json_decode($response, true);

        if ($decodedResponse != null && $decodedResponse['error']) {

          $response = $decodedResponse['error'];

        }

        throw new Google_AuthException("Error fetching OAuth2 access token, message: '$response'", $request->getResponseHttpCode());

      }

    }

    $authUrl = $this->createAuthUrl($service['scope']);

    header('Location: ' . $authUrl);

    return true;

  }

  /**

   * Create a URL to obtain user authorization.

   * The authorization endpoint allows the user to first

   * authenticate, and then grant/deny the access request.

   * @param string $scope The scope is expressed as a list of space-delimited strings.

   * @return string

   */

  public function createAuthUrl($scope) {

    $params = array(

        'response_type=code',

        'redirect_uri=' . urlencode($this->redirectUri),

        'client_id=' . urlencode($this->clientId),

        'scope=' . urlencode($scope),

        'access_type=' . urlencode($this->accessType),

        'approval_prompt=' . urlencode($this->approvalPrompt)

    );

    if (isset($this->state)) {

      $params[] = 'state=' . urlencode($this->state);

    }

    $params = implode('&', $params);

    return self::OAUTH2_AUTH_URL . "?$params";

  }

  /**

   * @param string $token

   * @throws Google_AuthException

   */

  public function setAccessToken($token) {

    $token = json_decode($token, true);

    if ($token == null) {

      throw new Google_AuthException('Could not json decode the token');

    }

    if (! isset($token['access_token'])) {

      throw new Google_AuthException("Invalid token format");

    }

    $this->token = $token;

  }

  public function getAccessToken() {

    return json_encode($this->token);

  }

  public function setDeveloperKey($developerKey) {

    $this->developerKey = $developerKey;

  }

  public function setState($state) {

    $this->state = $state;

  }

  public function setAccessType($accessType) {

    $this->accessType = $accessType;

  }

  public function setApprovalPrompt($approvalPrompt) {

    $this->approvalPrompt = $approvalPrompt;

  }

  public function setAssertionCredentials(Google_AssertionCredentials $creds) {

    $this->assertionCredentials = $creds;

  }

  /**

   * Include an accessToken in a given apiHttpRequest.

   * @param Google_HttpRequest $request

   * @return Google_HttpRequest

   * @throws Google_AuthException

   */

  public function sign(Google_HttpRequest $request) {

    // add the developer key to the request before signing it

    if ($this->developerKey) {

      $requestUrl = $request->getUrl();

      $requestUrl .= (strpos($request->getUrl(), '?') === false) ? '?' : '&';

      $requestUrl .=  'key=' . urlencode($this->developerKey);

      $request->setUrl($requestUrl);

    }

    // Cannot sign the request without an OAuth access token.

    if (null == $this->token && null == $this->assertionCredentials) {

      return $request;

    }

    // Check if the token is set to expire in the next 30 seconds

    // (or has already expired).

    if ($this->isAccessTokenExpired()) {

      if ($this->assertionCredentials) {

        $this->refreshTokenWithAssertion();

      } else {

        if (! array_key_exists('refresh_token', $this->token)) {

            throw new Google_AuthException("The OAuth 2.0 access token has expired, "

                . "and a refresh token is not available. Refresh tokens are not "

                . "returned for responses that were auto-approved.");

        }

        $this->refreshToken($this->token['refresh_token']);

      }

    }

    // Add the OAuth2 header to the request

    $request->setRequestHeaders(

        array('Authorization' => 'Bearer ' . $this->token['access_token'])

    );

    return $request;

  }

  /**

   * Fetches a fresh access token with the given refresh token.

   * @param string $refreshToken

   * @return void

   */

  public function refreshToken($refreshToken) {

    $this->refreshTokenRequest(array(

        'client_id' => $this->clientId,

        'client_secret' => $this->clientSecret,

        'refresh_token' => $refreshToken,

        'grant_type' => 'refresh_token'

    ));

  }

  /**

   * Fetches a fresh access token with a given assertion token.

   * @param Google_AssertionCredentials $assertionCredentials optional.

   * @return void

   */

  public function refreshTokenWithAssertion($assertionCredentials = null) {

    if (!$assertionCredentials) {

      $assertionCredentials = $this->assertionCredentials;

    }

    $this->refreshTokenRequest(array(

        'grant_type' => 'assertion',

        'assertion_type' => $assertionCredentials->assertionType,

        'assertion' => $assertionCredentials->generateAssertion(),

    ));

  }

  private function refreshTokenRequest($params) {

    $http = new Google_HttpRequest(self::OAUTH2_TOKEN_URI, 'POST', array(), $params);

    $request = Google_Client::$io->makeRequest($http);

    $code = $request->getResponseHttpCode();

    $body = $request->getResponseBody();

    if (200 == $code) {

      $token = json_decode($body, true);

      if ($token == null) {

        throw new Google_AuthException("Could not json decode the access token");

      }

      if (! isset($token['access_token']) || ! isset($token['expires_in'])) {

        throw new Google_AuthException("Invalid token format");

      }

      $this->token['access_token'] = $token['access_token'];

      $this->token['expires_in'] = $token['expires_in'];

      $this->token['created'] = time();

    } else {

      throw new Google_AuthException("Error refreshing the OAuth2 token, message: '$body'", $code);

    }

  }

    /**

     * Revoke an OAuth2 access token or refresh token. This method will revoke the current access

     * token, if a token isn't provided.

     * @throws Google_AuthException

     * @param string|null $token The token (access token or a refresh token) that should be revoked.

     * @return boolean Returns True if the revocation was successful, otherwise False.

     */

  public function revokeToken($token = null) {

    if (!$token) {

      $token = $this->token['access_token'];

    }

    $request = new Google_HttpRequest(self::OAUTH2_REVOKE_URI, 'POST', array(), "token=$token");

    $response = Google_Client::$io->makeRequest($request);

    $code = $response->getResponseHttpCode();

    if ($code == 200) {

      $this->token = null;

      return true;

    }

    return false;

  }

  /**

   * Returns if the access_token is expired.

   * @return bool Returns True if the access_token is expired.

   */

  public function isAccessTokenExpired() {

    if (null == $this->token) {

      return true;

    }

    // If the token is set to expire in the next 30 seconds.

    $expired = ($this->token['created']

        + ($this->token['expires_in'] - 30)) < time();

    return $expired;

  }

  // Gets federated sign-on certificates to use for verifying identity tokens.

  // Returns certs as array structure, where keys are key ids, and values

  // are PEM encoded certificates.

  private function getFederatedSignOnCerts() {

    // This relies on makeRequest caching certificate responses.

    $request = Google_Client::$io->makeRequest(new Google_HttpRequest(

        self::OAUTH2_FEDERATED_SIGNON_CERTS_URL));

    if ($request->getResponseHttpCode() == 200) {

      $certs = json_decode($request->getResponseBody(), true);

      if ($certs) {

        return $certs;

      }

    }

    throw new Google_AuthException(

        "Failed to retrieve verification certificates: '" .

            $request->getResponseBody() . "'.",

        $request->getResponseHttpCode());

  }

  /**

   * Verifies an id token and returns the authenticated apiLoginTicket.

   * Throws an exception if the id token is not valid.

   * The audience parameter can be used to control which id tokens are

   * accepted.  By default, the id token must have been issued to this OAuth2 client.

   *

   * @param $id_token

   * @param $audience

   * @return Google_LoginTicket

   */

  public function verifyIdToken($id_token = null, $audience = null) {

    if (!$id_token) {

      $id_token = $this->token['id_token'];

    }

    $certs = $this->getFederatedSignonCerts();

    if (!$audience) {

      $audience = $this->clientId;

    }

    return $this->verifySignedJwtWithCerts($id_token, $certs, $audience);

  }

  // Verifies the id token, returns the verified token contents.

  // Visible for testing.

  function verifySignedJwtWithCerts($jwt, $certs, $required_audience) {

    $segments = explode(".", $jwt);

    if (count($segments) != 3) {

      throw new Google_AuthException("Wrong number of segments in token: $jwt");

    }

    $signed = $segments[0] . "." . $segments[1];

    $signature = Google_Utils::urlSafeB64Decode($segments[2]);

    // Parse envelope.

    $envelope = json_decode(Google_Utils::urlSafeB64Decode($segments[0]), true);

    if (!$envelope) {

      throw new Google_AuthException("Can't parse token envelope: " . $segments[0]);

    }

    // Parse token

    $json_body = Google_Utils::urlSafeB64Decode($segments[1]);

    $payload = json_decode($json_body, true);

    if (!$payload) {

      throw new Google_AuthException("Can't parse token payload: " . $segments[1]);

    }

    // Check signature

    $verified = false;

    foreach ($certs as $keyName => $pem) {

      $public_key = new Google_PemVerifier($pem);

      if ($public_key->verify($signed, $signature)) {

        $verified = true;

        break;

      }

    }

    if (!$verified) {

      throw new Google_AuthException("Invalid token signature: $jwt");

    }

    // Check issued-at timestamp

    $iat = 0;

    if (array_key_exists("iat", $payload)) {

      $iat = $payload["iat"];

    }

    if (!$iat) {

      throw new Google_AuthException("No issue time in token: $json_body");

    }

    $earliest = $iat - self::CLOCK_SKEW_SECS;

    // Check expiration timestamp

    $now = time();

    $exp = 0;

    if (array_key_exists("exp", $payload)) {

      $exp = $payload["exp"];

    }

    if (!$exp) {

      throw new Google_AuthException("No expiration time in token: $json_body");

    }

    if ($exp >= $now + self::MAX_TOKEN_LIFETIME_SECS) {

      throw new Google_AuthException(

          "Expiration time too far in future: $json_body");

    }

    $latest = $exp + self::CLOCK_SKEW_SECS;

    if ($now < $earliest) {

      throw new Google_AuthException(

          "Token used too early, $now < $earliest: $json_body");

    }

    if ($now > $latest) {

      throw new Google_AuthException(

          "Token used too late, $now > $latest: $json_body");

    }

    // TODO(beaton): check issuer field?

    // Check audience

    $aud = $payload["aud"];

    if ($aud != $required_audience) {

      throw new Google_AuthException("Wrong recipient, $aud != $required_audience: $json_body");

    }

    // All good.

    return new Google_LoginTicket($envelope, $payload);

  }

}