307 lines
11 KiB
PHP
Executable File
307 lines
11 KiB
PHP
Executable File
<?php
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/*
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* Copyright 2022 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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namespace Google\Auth\Credentials;
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use Google\Auth\CacheTrait;
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use Google\Auth\CredentialsLoader;
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use Google\Auth\FetchAuthTokenInterface;
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use Google\Auth\GetUniverseDomainInterface;
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use Google\Auth\HttpHandler\HttpClientCache;
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use Google\Auth\HttpHandler\HttpHandlerFactory;
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use Google\Auth\IamSignerTrait;
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use Google\Auth\SignBlobInterface;
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use GuzzleHttp\Psr7\Request;
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use InvalidArgumentException;
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use LogicException;
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/**
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* **IMPORTANT**:
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* This class does not validate the credential configuration. A security
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* risk occurs when a credential configuration configured with malicious urls
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* is used.
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* When the credential configuration is accepted from an
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* untrusted source, you should validate it before creating this class.
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* @see https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
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*/
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class ImpersonatedServiceAccountCredentials extends CredentialsLoader implements
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SignBlobInterface,
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GetUniverseDomainInterface
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{
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use CacheTrait;
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use IamSignerTrait;
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private const CRED_TYPE = 'imp';
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private const IAM_SCOPE = 'https://www.googleapis.com/auth/iam';
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private const ID_TOKEN_IMPERSONATION_URL =
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'https://iamcredentials.UNIVERSE_DOMAIN/v1/projects/-/serviceAccounts/%s:generateIdToken';
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/**
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* @var string
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*/
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protected $impersonatedServiceAccountName;
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protected FetchAuthTokenInterface $sourceCredentials;
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private string $serviceAccountImpersonationUrl;
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/**
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* @var string[]
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*/
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private array $delegates;
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/**
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* @var string|string[]
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*/
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private string|array $targetScope;
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private int $lifetime;
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/**
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* @var array<mixed>|null
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*/
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protected array|null $lastReceivedToken = null;
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/**
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* Instantiate an instance of ImpersonatedServiceAccountCredentials from a credentials file that
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* has be created with the --impersonate-service-account flag.
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*
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* @param string|string[]|null $scope The scope of the access request, expressed either as an
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* array or as a space-delimited string.
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* @param string|array<mixed> $jsonKey JSON credential file path or JSON array credentials {
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* JSON credentials as an associative array.
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*
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* @type string $service_account_impersonation_url The URL to the service account
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* @type string|FetchAuthTokenInterface $source_credentials The source credentials to impersonate
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* @type int $lifetime The lifetime of the impersonated credentials
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* @type string[] $delegates The delegates to impersonate
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* }
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* @param string|null $targetAudience The audience to request an ID token.
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* @param string|string[]|null $defaultScope The scopes to be used if no "scopes" field exists
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* in the `$jsonKey`.
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*/
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public function __construct(
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string|array|null $scope,
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string|array $jsonKey,
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private ?string $targetAudience = null,
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string|array|null $defaultScope = null,
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) {
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if (is_string($jsonKey)) {
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if (!file_exists($jsonKey)) {
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throw new InvalidArgumentException('file does not exist');
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}
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$json = file_get_contents($jsonKey);
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if (!$jsonKey = json_decode((string) $json, true)) {
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throw new LogicException('invalid json for auth config');
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}
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}
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if (!array_key_exists('service_account_impersonation_url', $jsonKey)) {
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throw new LogicException(
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'json key is missing the service_account_impersonation_url field'
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);
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}
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if (!array_key_exists('source_credentials', $jsonKey)) {
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throw new LogicException('json key is missing the source_credentials field');
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}
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$jsonKeyScope = $jsonKey['scopes'] ?? null;
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$scope = $scope ?: $jsonKeyScope ?: $defaultScope;
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if ($scope && $targetAudience) {
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throw new InvalidArgumentException(
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'Scope and targetAudience cannot both be supplied'
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);
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}
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if (is_array($jsonKey['source_credentials'])) {
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if (!array_key_exists('type', $jsonKey['source_credentials'])) {
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throw new InvalidArgumentException('json key source credentials are missing the type field');
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}
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if (
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$targetAudience !== null
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&& $jsonKey['source_credentials']['type'] === 'service_account'
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) {
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// Service account tokens MUST request a scope, and as this token is only used to impersonate
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// an ID token, the narrowest scope we can request is `iam`.
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$scope = self::IAM_SCOPE;
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}
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$jsonKey['source_credentials'] = match ($jsonKey['source_credentials']['type'] ?? null) {
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// Do not pass $defaultScope to ServiceAccountCredentials
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'service_account' => new ServiceAccountCredentials($scope, $jsonKey['source_credentials']),
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'authorized_user' => new UserRefreshCredentials($scope, $jsonKey['source_credentials']),
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'external_account' => new ExternalAccountCredentials($scope, $jsonKey['source_credentials']),
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default => throw new \InvalidArgumentException('invalid value in the type field'),
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};
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}
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$this->targetScope = $scope ?? [];
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$this->lifetime = $jsonKey['lifetime'] ?? 3600;
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$this->delegates = $jsonKey['delegates'] ?? [];
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$this->serviceAccountImpersonationUrl = $jsonKey['service_account_impersonation_url'];
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$this->impersonatedServiceAccountName = $this->getImpersonatedServiceAccountNameFromUrl(
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$this->serviceAccountImpersonationUrl
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);
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$this->sourceCredentials = $jsonKey['source_credentials'];
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}
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/**
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* Helper function for extracting the Server Account Name from the URL saved in the account
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* credentials file.
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*
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* @param $serviceAccountImpersonationUrl string URL from "service_account_impersonation_url"
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* @return string Service account email or ID.
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*/
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private function getImpersonatedServiceAccountNameFromUrl(
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string $serviceAccountImpersonationUrl
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): string {
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$fields = explode('/', $serviceAccountImpersonationUrl);
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$lastField = end($fields);
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$splitter = explode(':', $lastField);
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return $splitter[0];
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}
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/**
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* Get the client name from the keyfile
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*
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* In this implementation, it will return the issuers email from the oauth token.
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*
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* @param callable|null $unusedHttpHandler not used by this credentials type.
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* @return string Token issuer email
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*/
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public function getClientName(?callable $unusedHttpHandler = null)
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{
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return $this->impersonatedServiceAccountName;
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}
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/**
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* @param callable|null $httpHandler
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*
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* @return array<mixed> {
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* A set of auth related metadata, containing the following
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*
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* @type string $access_token
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* @type int $expires_in
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* @type string $scope
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* @type string $token_type
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* @type string $id_token
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* }
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*/
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public function fetchAuthToken(?callable $httpHandler = null)
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{
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$httpHandler = $httpHandler ?? HttpHandlerFactory::build(HttpClientCache::getHttpClient());
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// The FetchAuthTokenInterface technically does not have a "headers" argument, but all of
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// the implementations do. Additionally, passing in more parameters than the function has
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// defined is allowed in PHP. So we'll just ignore the phpstan error here.
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// @phpstan-ignore-next-line
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$authToken = $this->sourceCredentials->fetchAuthToken(
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$httpHandler,
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$this->applyTokenEndpointMetrics([], 'at')
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);
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$headers = $this->applyTokenEndpointMetrics([
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'Content-Type' => 'application/json',
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'Cache-Control' => 'no-store',
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'Authorization' => sprintf('Bearer %s', $authToken['access_token'] ?? $authToken['id_token']),
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], $this->isIdTokenRequest() ? 'it' : 'at');
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$body = match ($this->isIdTokenRequest()) {
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true => [
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'audience' => $this->targetAudience,
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'includeEmail' => true,
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],
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false => [
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'scope' => $this->targetScope,
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'delegates' => $this->delegates,
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'lifetime' => sprintf('%ss', $this->lifetime),
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]
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};
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$url = $this->serviceAccountImpersonationUrl;
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if ($this->isIdTokenRequest()) {
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$regex = '/serviceAccounts\/(?<email>[^:]+):generateAccessToken$/';
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if (!preg_match($regex, $url, $matches)) {
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throw new InvalidArgumentException(
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'Invalid service account impersonation URL - unable to parse service account email'
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);
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}
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$url = str_replace(
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'UNIVERSE_DOMAIN',
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$this->getUniverseDomain(),
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sprintf(self::ID_TOKEN_IMPERSONATION_URL, $matches['email'])
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);
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}
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$request = new Request(
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'POST',
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$url,
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$headers,
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(string) json_encode($body)
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);
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$response = $httpHandler($request);
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$body = json_decode((string) $response->getBody(), true);
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return $this->lastReceivedToken = match ($this->isIdTokenRequest()) {
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true => ['id_token' => $body['token']],
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false => [
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'access_token' => $body['accessToken'],
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'expires_at' => strtotime($body['expireTime']),
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]
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};
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}
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/**
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* Returns the Cache Key for the credentials
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* The cache key is the same as the UserRefreshCredentials class
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*
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* @return string
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*/
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public function getCacheKey()
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{
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return $this->getFullCacheKey(
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$this->serviceAccountImpersonationUrl . $this->sourceCredentials->getCacheKey()
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);
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}
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/**
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* @return array<mixed>
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*/
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public function getLastReceivedToken()
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{
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return $this->lastReceivedToken;
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}
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protected function getCredType(): string
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{
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return self::CRED_TYPE;
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}
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private function isIdTokenRequest(): bool
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{
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return !is_null($this->targetAudience);
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}
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public function getUniverseDomain(): string
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{
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return $this->sourceCredentials instanceof GetUniverseDomainInterface
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? $this->sourceCredentials->getUniverseDomain()
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: self::DEFAULT_UNIVERSE_DOMAIN;
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}
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}
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