<?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';
public $requestVisibleActions;
/** @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 the list of scopes contains plus.login, add request_visible_actions
// to auth URL
if(strpos($scope, 'plus.login') && count($this->requestVisibleActions) > 0) {
$params[] = 'request_visible_actions=' .
urlencode($this->requestVisibleActions);
}
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);
}
}
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