Viewing file:  ScopedAccessTokenSubscriber.php (5.01 KB) -rw-r--r--
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<?php
/*
* Copyright 2015 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.
*/
namespace Google\Auth\Subscriber;
use Google\Auth\CacheTrait;
use GuzzleHttp\Event\BeforeEvent;
use GuzzleHttp\Event\RequestEvents;
use GuzzleHttp\Event\SubscriberInterface;
use Psr\Cache\CacheItemPoolInterface;
/**
* ScopedAccessTokenSubscriber is a Guzzle Subscriber that adds an Authorization
* header provided by a closure.
*
* The closure returns an access token, taking the scope, either a single
* string or an array of strings, as its value. If provided, a cache will be
* used to preserve the access token for a given lifetime.
*
* Requests will be accessed with the authorization header:
*
* 'authorization' 'Bearer <access token obtained from the closure>'
*/
class ScopedAccessTokenSubscriber implements SubscriberInterface
{
use CacheTrait;
const DEFAULT_CACHE_LIFETIME = 1500;
/**
* @var CacheItemPoolInterface
*/
private $cache;
/**
* @var callable The access token generator function
*/
private $tokenFunc;
/**
* @var array|string The scopes used to generate the token
*/
private $scopes;
/**
* @var array
*/
private $cacheConfig;
/**
* Creates a new ScopedAccessTokenSubscriber.
*
* @param callable $tokenFunc a token generator function
* @param array|string $scopes the token authentication scopes
* @param array $cacheConfig configuration for the cache when it's present
* @param CacheItemPoolInterface $cache an implementation of CacheItemPoolInterface
*/
public function __construct(
callable $tokenFunc,
$scopes,
array $cacheConfig = null,
CacheItemPoolInterface $cache = null
) {
$this->tokenFunc = $tokenFunc;
if (!(is_string($scopes) || is_array($scopes))) {
throw new \InvalidArgumentException(
'wants scope should be string or array'
);
}
$this->scopes = $scopes;
if (!is_null($cache)) {
$this->cache = $cache;
$this->cacheConfig = array_merge([
'lifetime' => self::DEFAULT_CACHE_LIFETIME,
'prefix' => '',
], $cacheConfig);
}
}
/**
* @return array
*/
public function getEvents()
{
return ['before' => ['onBefore', RequestEvents::SIGN_REQUEST]];
}
/**
* Updates the request with an Authorization header when auth is 'scoped'.
*
* E.g this could be used to authenticate using the AppEngine AppIdentityService.
*
* Example:
* ```
* use google\appengine\api\app_identity\AppIdentityService;
* use Google\Auth\Subscriber\ScopedAccessTokenSubscriber;
* use GuzzleHttp\Client;
*
* $scope = 'https://www.googleapis.com/auth/taskqueue'
* $subscriber = new ScopedAccessToken(
* 'AppIdentityService::getAccessToken',
* $scope,
* ['prefix' => 'Google\Auth\ScopedAccessToken::'],
* $cache = new Memcache()
* );
*
* $client = new Client([
* 'base_url' => 'https://www.googleapis.com/taskqueue/v1beta2/projects/',
* 'defaults' => ['auth' => 'scoped']
* ]);
* $client->getEmitter()->attach($subscriber);
*
* $res = $client->get('myproject/taskqueues/myqueue');
* ```
*
* @param BeforeEvent $event
*/
public function onBefore(BeforeEvent $event)
{
// Requests using "auth"="scoped" will be authorized.
$request = $event->getRequest();
if ($request->getConfig()['auth'] != 'scoped') {
return;
}
$auth_header = 'Bearer ' . $this->fetchToken();
$request->setHeader('authorization', $auth_header);
}
/**
* @return string
*/
private function getCacheKey()
{
$key = null;
if (is_string($this->scopes)) {
$key .= $this->scopes;
} elseif (is_array($this->scopes)) {
$key .= implode(':', $this->scopes);
}
return $key;
}
/**
* Determine if token is available in the cache, if not call tokenFunc to
* fetch it.
*
* @return string
*/
private function fetchToken()
{
$cacheKey = $this->getCacheKey();
$cached = $this->getCachedValue($cacheKey);
if (!empty($cached)) {
return $cached;
}
$token = call_user_func($this->tokenFunc, $this->scopes);
$this->setCachedValue($cacheKey, $token);
return $token;
}
}
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