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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\Middleware;
use Google\Auth\CacheTrait;
use Psr\Cache\CacheItemPoolInterface;
use Psr\Http\Message\RequestInterface;
/**
* ScopedAccessTokenMiddleware is a Guzzle Middleware 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 <value of auth_token>'
*/
class ScopedAccessTokenMiddleware
{
use CacheTrait;
const DEFAULT_CACHE_LIFETIME = 1500;
/**
* @var CacheItemPoolInterface
*/
private $cache;
/**
* @var array configuration
*/
private $cacheConfig;
/**
* @var callable
*/
private $tokenFunc;
/**
* @var array|string
*/
private $scopes;
/**
* Creates a new ScopedAccessTokenMiddleware.
*
* @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);
}
}
/**
* Updates the request with an Authorization header when auth is 'scoped'.
*
* E.g this could be used to authenticate using the AppEngine
* AppIdentityService.
*
* use google\appengine\api\app_identity\AppIdentityService;
* use Google\Auth\Middleware\ScopedAccessTokenMiddleware;
* use GuzzleHttp\Client;
* use GuzzleHttp\HandlerStack;
*
* $scope = 'https://www.googleapis.com/auth/taskqueue'
* $middleware = new ScopedAccessTokenMiddleware(
* 'AppIdentityService::getAccessToken',
* $scope,
* [ 'prefix' => 'Google\Auth\ScopedAccessToken::' ],
* $cache = new Memcache()
* );
* $stack = HandlerStack::create();
* $stack->push($middleware);
*
* $client = new Client([
* 'handler' => $stack,
* 'base_url' => 'https://www.googleapis.com/taskqueue/v1beta2/projects/',
* 'auth' => 'scoped' // authorize all requests
* ]);
*
* $res = $client->get('myproject/taskqueues/myqueue');
*
* @param callable $handler
*
* @return \Closure
*/
public function __invoke(callable $handler)
{
return function (RequestInterface $request, array $options) use ($handler) {
// Requests using "auth"="scoped" will be authorized.
if (!isset($options['auth']) || $options['auth'] !== 'scoped') {
return $handler($request, $options);
}
$request = $request->withHeader('authorization', 'Bearer ' . $this->fetchToken());
return $handler($request, $options);
};
}
/**
* @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;
}
}
|
