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Arsse/lib/REST/Microsub/Auth.php

183 lines
8.4 KiB
PHP

<?php
/** @license MIT
* Copyright 2017 J. King, Dustin Wilson et al.
* See LICENSE and AUTHORS files for details */
declare(strict_types=1);
namespace JKingWeb\Arsse\REST\Microsub;
use JKingWeb\Arsse\Arsse;
use JKingWeb\Arsse\Misc\URL;
use JKingWeb\Arsse\Misc\Date;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Message\ResponseInterface;
use Zend\Diactoros\Response\HtmlResponse;
use Zend\Diactoros\Response\JsonResponse;
use Zend\Diactoros\Response\EmptyResponse;
class Auth extends \JKingWeb\Arsse\REST\AbstractHandler {
/** The scopes which we grant to Microsub clients. Mute and block are not included because they have no meaning in an RSS/Atom context; this may signal to clients to suppress muting and blocking in their UI */
const SCOPES = "read follow channels";
const FUNCTIONS = [
'discovery' => ['GET' => "opDiscovery"],
'login' => ['GET' => "opLogin", 'POST' => "opCodeVerification"],
'issue' => ['POST' => "opIssue"],
];
public function __construct() {
}
public function dispatch(ServerRequestInterface $req): ResponseInterface {
// ensure that a user name is specified in the path
// if the path is empty or contains a slash, this is not a URL we handle
$id = parse_url($req->getRequestTarget())['path'] ?? "";
if (!strlen($id) || strpos($id, "/") !== false) {
return new EmptyResponse(404);
}
$id = rawurldecode($id);
// gather the query parameters and act on the "proc" parameter
$process = $req->getQueryParams()['proc'] ?? "discovery";
$method = $req->getMethod();
if (isset(self::FUNCTIONS[$process])) {
return new EmptyResponse(404);
} elseif ($method === "OPTIONS") {
$fields = ['Allow' => implode(",", array_keys(self::FUNCTIONS[$process]))];
if (isset(self::FUNCTIONS[$process]['POST'])) {
$fields['Accept'] = "application/x-www-form-urlencoded";
}
return new EmptyResponse(204, $fields);
} elseif (isset(self::FUNCTIONS[$process][$method])) {
return new EmptyResponse(405, ['Allow' => implode(",", array_keys(self::FUNCTIONS[$process]))]);
} else {
$func = self::FUNCTIONS[$process][$method];
return $this->$func($id, $req);
}
}
/** Produces a user-identifier URL consiustent with the request
*
* This involves reconstructing the scheme and authority based on $_SERVER
* variables; it may fail depending on server configuration
*/
protected function buildIdentifier(ServerRequestInterface $req, bool $baseOnly = false): string {
// construct the base user identifier URL; the user is never checked against the database
$s = $req->getServerParams();
$path = $req->getRequestTarget()['path'];
$https = (strlen($s['HTTPS'] ?? "") && $s['HTTPS'] !== "off");
$port = (int) ($s['SERVER_PORT'] ?? 0);
$port = (!$port || ($https && $port == 443) || (!$https && $port == 80)) ? "" : ":$port";
$base = URL::normalize(($https ? "https" : "http")."://".$s['HTTP_HOST'].$port."/");
return !$baseOnly ? URL::normalize($base.$path) : $base;
}
/** Presents a very basic user profile for discovery purposes
*
* The HTML document itself consists only of link elements and an
* encoding declaration; Link header-fields are also included for
* HEAD requests
*
* Since discovery is publicly accessible, we produce a discovery
* page for all potential user name so as not to facilitate user
* enumeration
*
* @see https://indieweb.org/Microsub-spec#Discovery
*/
protected function opDiscovery(string $user, ServerRequestInterface $req): ResponseInterface {
$base = $this->buildIdentifier($req, true);
$id = $this->buildIdentifier($req);
$urlAuth = $id."?proc=login";
$urlToken = $id."?proc=issue";
$urlService = $base."microsub";
// output an extremely basic identity resource
$html = '<meta charset="UTF-8"><link rel="authorization_endpoint" href="'.htmlspecialchars($urlAuth).'"><link rel="token_endpoint" href="'.htmlspecialchars($urlToken).'"><link rel="microsub" href="'.htmlspecialchars($urlService).'">';
return new HtmlResponse($html, 200, [
"Link: <$urlAuth>; rel=\"authorization_endpoint\"",
"Link: <$urlToken>; rel=\"token_endpoint\"",
"Link: <$urlService>; rel=\"microsub\"",
]);
}
/** Handles the authentication/authorization process
*
* Authentication is achieved via an HTTP Basic authentiation
* challenge; once the user successfully logs in a code is issued
* and redirection occurs. Scopes are for all intents and purposes
* ignored and client information is not presented.
*
* @see https://indieauth.spec.indieweb.org/#authentication-request
*/
protected function opLogin(string $user, ServerRequestInterface $req): ResponseInterface {
if (!$req->getAttribute("authenticated", false)) {
// user has not yet logged in, or has failed to log in
return new EmptyResponse(401);
} else {
// user has logged in
// ensure the logged-in user matches the IndieAuth identifier URL
$id = $req->getAttribute("authenticatedUser");
$query = $req->getQueryParams();
$url = buildIdentifier($req);
if ($user !== $id || URL::normalize($query['me']) !== $url) {
return new EmptyResponse(403);
} else {
$redir = URL::normalize(rawurldecode($query['redirect_uri']));
$state = $query['state'] ?? "";
// check that the redirect URL is an absolute one
if (!URL::absolute($redir)) {
return new EmptyResponse(400);
}
// store the client ID and redirect URL
$data = json_encode([
'id' => $query['client_id'],
'url' => $query['redirect_uri'],
],\JSON_UNESCAPED_SLASHES | \JSON_UNESCAPED_UNICODE);
// issue an authorization code and build the redirect URL
$code = Arsse::$db->tokenCreate($id, "microsub.auth", null, Date::add("PT2M"), $data);
$next = URL::queryAppend($redir, "code=$code&state=$state");
return new EmptyResponse(302, ["Location: $next"]);
}
}
}
/** Validates an authorization code against client-provided values
*
* The redirect URL and client ID are checked, as is the user ID
*
* If everything checks out the canonical user URL is supposed to be returned;
* we don't actually know what the canonical URL is modulo URL encoding, but it
* doesn't actually matter for our purposes
*
* @see https://indieauth.spec.indieweb.org/#authorization-code-verification
*/
protected function opCodeVerification(string $user, ServerRequestInterface $req): ResponseInterface {
$post = $req->getParsedBody();
try {
// validate the request parameters
$code = $post['code'] ?? "";
$id = $post['client_id'] ?? "";
$url = $post['redirect_uri'] ?? "";
if (!strlen($code) || !strlen($id) || !strlen($url)) {
throw new ExceptionAuth("invalid_request");
}
// check that the token exists
$token = Arsse::$db->tokenLookup("microsub.auth", $code);
if (!$token) {
throw new ExceptionAuth("unsupported_grant_type");
}
$data = @json_decode($token['data'], true);
// validate the token
if ($token['user'] !== $user || !is_array($data) || $data['id'] !== $id || $data['url'] !== $url) {
throw new ExceptionAuth("unsupported_grant_type");
} else {
return new JsonResponse(['me' => $this->buildIdentifier($req)]);
}
} catch (ExceptionAuth $e) {
// human-readable error messages could be added, but these must be ASCII per OAuth, so there's probably not much point
// see https://tools.ietf.org/html/rfc6749#section-5.2
return new JsonResponse(['error' => $e->getMessage()], 400);
}
}
protected function opIssue(string $user, ServerRequestInterface $req): ResponseInterface {
$post = $req->getParsedBody();
}
}