| 1 |
<?php |
| 2 |
/** |
| 3 |
* OAuth 2.0 Server for ActivityPub C2S. |
| 4 |
* |
| 5 |
* @package Activitypub |
| 6 |
*/ |
| 7 |
|
| 8 |
namespace Activitypub\OAuth; |
| 9 |
|
| 10 |
use Activitypub\Sanitize; |
| 11 |
|
| 12 |
/** |
| 13 |
* Server class for OAuth 2.0 authentication and PKCE verification. |
| 14 |
* |
| 15 |
* Integrates with WordPress REST API authentication system. |
| 16 |
*/ |
| 17 |
class Server { |
| 18 |
/** |
| 19 |
* The current validated token for this request. |
| 20 |
* |
| 21 |
* @var Token|null |
| 22 |
*/ |
| 23 |
private static $current_token = null; |
| 24 |
|
| 25 |
/** |
| 26 |
* Initialize the OAuth server. |
| 27 |
*/ |
| 28 |
public static function init() { |
| 29 |
// Hook into REST authentication - priority 20 to run after default auth. |
| 30 |
\add_filter( 'rest_authentication_errors', array( self::class, 'authenticate_oauth' ), 20 ); |
| 31 |
|
| 32 |
// Schedule cleanup cron. |
| 33 |
if ( ! \wp_next_scheduled( 'activitypub_oauth_cleanup' ) ) { |
| 34 |
\wp_schedule_event( time(), 'daily', 'activitypub_oauth_cleanup' ); |
| 35 |
} |
| 36 |
\add_action( 'activitypub_oauth_cleanup', array( self::class, 'cleanup' ) ); |
| 37 |
} |
| 38 |
|
| 39 |
/** |
| 40 |
* Authenticate OAuth Bearer token for REST API requests. |
| 41 |
* |
| 42 |
* @param \WP_Error|null|bool $result Authentication result from previous filters. |
| 43 |
* @return \WP_Error|null|bool Authentication result. |
| 44 |
*/ |
| 45 |
public static function authenticate_oauth( $result ) { |
| 46 |
/* |
| 47 |
* Reset OAuth state at the start of each authentication to prevent |
| 48 |
* leaking state between multiple REST dispatches in the same process. |
| 49 |
*/ |
| 50 |
self::$current_token = null; |
| 51 |
|
| 52 |
$token = self::get_bearer_token(); |
| 53 |
|
| 54 |
if ( ! $token ) { |
| 55 |
// No Bearer token — respect errors from earlier auth filters. |
| 56 |
return $result; |
| 57 |
} |
| 58 |
|
| 59 |
$validated = Token::validate( $token ); |
| 60 |
|
| 61 |
if ( \is_wp_error( $validated ) ) { |
| 62 |
return $validated; |
| 63 |
} |
| 64 |
|
| 65 |
self::$current_token = $validated; |
| 66 |
\wp_set_current_user( $validated->get_user_id() ); |
| 67 |
|
| 68 |
return true; |
| 69 |
} |
| 70 |
|
| 71 |
/** |
| 72 |
* Get the current OAuth token from the request. |
| 73 |
* |
| 74 |
* @return Token|null The validated token or null. |
| 75 |
*/ |
| 76 |
public static function get_current_token() { |
| 77 |
return self::$current_token; |
| 78 |
} |
| 79 |
|
| 80 |
/** |
| 81 |
* Check if the current request is authenticated via OAuth. |
| 82 |
* |
| 83 |
* @return bool True if OAuth authenticated. |
| 84 |
*/ |
| 85 |
public static function is_oauth_request() { |
| 86 |
return null !== self::$current_token; |
| 87 |
} |
| 88 |
|
| 89 |
/** |
| 90 |
* Check if the current token has a specific scope. |
| 91 |
* |
| 92 |
* @param string $scope The scope to check. |
| 93 |
* @return bool True if the current token has the scope. |
| 94 |
*/ |
| 95 |
public static function has_scope( $scope ) { |
| 96 |
if ( ! self::$current_token ) { |
| 97 |
return false; |
| 98 |
} |
| 99 |
|
| 100 |
return self::$current_token->has_scope( $scope ); |
| 101 |
} |
| 102 |
|
| 103 |
/** |
| 104 |
* Extract Bearer token from Authorization header. |
| 105 |
* |
| 106 |
* @return string|null The token string or null. |
| 107 |
*/ |
| 108 |
public static function get_bearer_token() { |
| 109 |
$auth_header = self::get_authorization_header(); |
| 110 |
|
| 111 |
if ( ! $auth_header ) { |
| 112 |
return null; |
| 113 |
} |
| 114 |
|
| 115 |
// Check for Bearer token. |
| 116 |
if ( 0 !== strpos( $auth_header, 'Bearer ' ) ) { |
| 117 |
return null; |
| 118 |
} |
| 119 |
|
| 120 |
return substr( $auth_header, 7 ); |
| 121 |
} |
| 122 |
|
| 123 |
/** |
| 124 |
* Get the Authorization header. |
| 125 |
* |
| 126 |
* @return string|null The authorization header value or null. |
| 127 |
*/ |
| 128 |
private static function get_authorization_header() { |
| 129 |
/* |
| 130 |
* Only wp_unslash() is used here — sanitize_text_field() could |
| 131 |
* corrupt opaque bearer tokens by stripping characters. |
| 132 |
*/ |
| 133 |
|
| 134 |
// phpcs:disable WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- Opaque auth token, must not be altered. |
| 135 |
if ( ! empty( $_SERVER['HTTP_AUTHORIZATION'] ) ) { |
| 136 |
return \wp_unslash( $_SERVER['HTTP_AUTHORIZATION'] ); |
| 137 |
} |
| 138 |
|
| 139 |
if ( ! empty( $_SERVER['REDIRECT_HTTP_AUTHORIZATION'] ) ) { |
| 140 |
return \wp_unslash( $_SERVER['REDIRECT_HTTP_AUTHORIZATION'] ); |
| 141 |
} |
| 142 |
// phpcs:enable WordPress.Security.ValidatedSanitizedInput.InputNotSanitized |
| 143 |
|
| 144 |
// Fallback: read from Apache's own header API (case-insensitive). |
| 145 |
if ( ! function_exists( 'apache_request_headers' ) ) { |
| 146 |
return null; |
| 147 |
} |
| 148 |
|
| 149 |
$headers = apache_request_headers(); |
| 150 |
|
| 151 |
foreach ( $headers as $key => $value ) { |
| 152 |
if ( 'authorization' === strtolower( $key ) ) { |
| 153 |
return $value; |
| 154 |
} |
| 155 |
} |
| 156 |
|
| 157 |
return null; |
| 158 |
} |
| 159 |
|
| 160 |
/** |
| 161 |
* Verify PKCE code_verifier against code_challenge. |
| 162 |
* |
| 163 |
* @param string $code_verifier The PKCE code verifier. |
| 164 |
* @param string $code_challenge The stored code challenge. |
| 165 |
* @param string $method The challenge method (only S256 is supported). |
| 166 |
* @return bool True if valid. |
| 167 |
*/ |
| 168 |
public static function verify_pkce( $code_verifier, $code_challenge, $method = 'S256' ) { |
| 169 |
return Authorization_Code::verify_pkce( $code_verifier, $code_challenge, $method ); |
| 170 |
} |
| 171 |
|
| 172 |
/** |
| 173 |
* Generate a cryptographically secure random string. |
| 174 |
* |
| 175 |
* @param int $length The length of the string in bytes. |
| 176 |
* @return string The random string as hex. |
| 177 |
*/ |
| 178 |
public static function generate_token( $length = 32 ) { |
| 179 |
return Token::generate_token( $length ); |
| 180 |
} |
| 181 |
|
| 182 |
/** |
| 183 |
* Permission callback for OAuth-protected endpoints. |
| 184 |
* |
| 185 |
* @param \WP_REST_Request $request The REST request. |
| 186 |
* @param string $scope Required scope (optional). |
| 187 |
* @return bool|\WP_Error True if authorized, error otherwise. |
| 188 |
*/ |
| 189 |
public static function check_oauth_permission( $request, $scope = null ) { |
| 190 |
/** |
| 191 |
* Filter to override OAuth permission check. |
| 192 |
* |
| 193 |
* Useful for testing. Return true to bypass OAuth check, false to continue. |
| 194 |
* |
| 195 |
* @param bool|null $result The permission result. Null to continue normal check. |
| 196 |
* @param \WP_REST_Request $request The REST request. |
| 197 |
* @param string|null $scope Required scope. |
| 198 |
*/ |
| 199 |
$override = \apply_filters( 'activitypub_oauth_check_permission', null, $request, $scope ); |
| 200 |
|
| 201 |
if ( null !== $override ) { |
| 202 |
return $override; |
| 203 |
} |
| 204 |
|
| 205 |
if ( ! self::is_oauth_request() ) { |
| 206 |
return new \WP_Error( |
| 207 |
'activitypub_oauth_required', |
| 208 |
\__( 'OAuth authentication required.', 'activitypub' ), |
| 209 |
array( 'status' => 401 ) |
| 210 |
); |
| 211 |
} |
| 212 |
|
| 213 |
if ( $scope && ! self::has_scope( $scope ) ) { |
| 214 |
return new \WP_Error( |
| 215 |
'activitypub_insufficient_scope', |
| 216 |
/* translators: %s: The required scope */ |
| 217 |
sprintf( \__( 'This action requires the "%s" scope.', 'activitypub' ), $scope ), |
| 218 |
array( 'status' => 403 ) |
| 219 |
); |
| 220 |
} |
| 221 |
|
| 222 |
return true; |
| 223 |
} |
| 224 |
|
| 225 |
/** |
| 226 |
* Run cleanup tasks for OAuth data. |
| 227 |
*/ |
| 228 |
public static function cleanup() { |
| 229 |
// Clean up expired tokens. |
| 230 |
Token::cleanup_expired(); |
| 231 |
|
| 232 |
// Clean up expired authorization codes. |
| 233 |
Authorization_Code::cleanup(); |
| 234 |
} |
| 235 |
|
| 236 |
/** |
| 237 |
* Get OAuth server metadata for discovery. |
| 238 |
* |
| 239 |
* @return array OAuth server metadata. |
| 240 |
*/ |
| 241 |
public static function get_metadata() { |
| 242 |
$base_url = \trailingslashit( \get_rest_url( null, ACTIVITYPUB_REST_NAMESPACE ) ); |
| 243 |
|
| 244 |
return array( |
| 245 |
'issuer' => \home_url(), |
| 246 |
'authorization_endpoint' => $base_url . 'oauth/authorize', |
| 247 |
'token_endpoint' => $base_url . 'oauth/token', |
| 248 |
'revocation_endpoint' => $base_url . 'oauth/revoke', |
| 249 |
'introspection_endpoint' => $base_url . 'oauth/introspect', |
| 250 |
'registration_endpoint' => $base_url . 'oauth/clients', |
| 251 |
'scopes_supported' => Scope::supported(), |
| 252 |
'response_types_supported' => array( 'code' ), |
| 253 |
'response_modes_supported' => array( 'query' ), |
| 254 |
'grant_types_supported' => array( 'authorization_code', 'refresh_token' ), |
| 255 |
'token_endpoint_auth_methods_supported' => array( 'none', 'client_secret_post', 'client_secret_basic' ), |
| 256 |
'introspection_endpoint_auth_methods_supported' => array( 'bearer' ), |
| 257 |
'code_challenge_methods_supported' => array( 'S256' ), |
| 258 |
'service_documentation' => 'https://github.com/swicg/activitypub-api', |
| 259 |
'client_id_metadata_document_supported' => true, |
| 260 |
); |
| 261 |
} |
| 262 |
|
| 263 |
/** |
| 264 |
* Handle OAuth authorization consent page via wp-login.php. |
| 265 |
* |
| 266 |
* This is triggered by wp-login.php?action=activitypub_authorize |
| 267 |
*/ |
| 268 |
public static function login_form_authorize() { |
| 269 |
// Require user to be logged in. |
| 270 |
if ( ! \is_user_logged_in() ) { |
| 271 |
\auth_redirect(); |
| 272 |
} |
| 273 |
|
| 274 |
$request_method = isset( $_SERVER['REQUEST_METHOD'] ) ? \sanitize_text_field( \wp_unslash( $_SERVER['REQUEST_METHOD'] ) ) : ''; |
| 275 |
|
| 276 |
if ( 'GET' === $request_method ) { |
| 277 |
self::render_authorize_form(); |
| 278 |
} elseif ( 'POST' === $request_method ) { |
| 279 |
self::process_authorize_form(); |
| 280 |
} |
| 281 |
|
| 282 |
exit; |
| 283 |
} |
| 284 |
|
| 285 |
/** |
| 286 |
* Render the OAuth authorization consent form. |
| 287 |
*/ |
| 288 |
private static function render_authorize_form() { |
| 289 |
// phpcs:disable WordPress.Security.NonceVerification.Recommended -- Initial form display, nonce checked on POST. |
| 290 |
|
| 291 |
// Check for error token (redirected from REST authorization endpoint). |
| 292 |
if ( isset( $_GET['auth_error'] ) ) { |
| 293 |
$token = \sanitize_text_field( \wp_unslash( $_GET['auth_error'] ) ); |
| 294 |
$error_message = \get_transient( 'ap_oauth_err_' . $token ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 295 |
\delete_transient( 'ap_oauth_err_' . $token ); |
| 296 |
|
| 297 |
if ( ! $error_message ) { |
| 298 |
$error_message = \__( 'An authorization error occurred. Please try again.', 'activitypub' ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 299 |
} |
| 300 |
|
| 301 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 302 |
return; |
| 303 |
} |
| 304 |
|
| 305 |
$authorize_params = array( |
| 306 |
'client_id' => isset( $_GET['client_id'] ) ? \sanitize_text_field( \wp_unslash( $_GET['client_id'] ) ) : '', |
| 307 |
'redirect_uri' => isset( $_GET['redirect_uri'] ) ? Sanitize::redirect_uri( \wp_unslash( $_GET['redirect_uri'] ) ) : '', // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- Sanitized via Sanitize::redirect_uri(). |
| 308 |
'scope' => isset( $_GET['scope'] ) ? \sanitize_text_field( \wp_unslash( $_GET['scope'] ) ) : '', |
| 309 |
'state' => isset( $_GET['state'] ) ? \wp_unslash( $_GET['state'] ) : '', // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- OAuth state is opaque; must be round-tripped exactly. |
| 310 |
'code_challenge' => isset( $_GET['code_challenge'] ) ? \sanitize_text_field( \wp_unslash( $_GET['code_challenge'] ) ) : '', |
| 311 |
'code_challenge_method' => isset( $_GET['code_challenge_method'] ) ? \sanitize_text_field( \wp_unslash( $_GET['code_challenge_method'] ) ) : 'S256', |
| 312 |
); |
| 313 |
// phpcs:enable WordPress.Security.NonceVerification.Recommended |
| 314 |
|
| 315 |
// Validate client. |
| 316 |
$client = Client::get( $authorize_params['client_id'] ); |
| 317 |
if ( \is_wp_error( $client ) ) { |
| 318 |
$error_message = $client->get_error_message(); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 319 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 320 |
return; |
| 321 |
} |
| 322 |
|
| 323 |
// Validate redirect URI. |
| 324 |
if ( ! $client->is_valid_redirect_uri( $authorize_params['redirect_uri'] ) ) { |
| 325 |
$error_message = \__( 'Invalid redirect URI for this client.', 'activitypub' ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 326 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 327 |
return; |
| 328 |
} |
| 329 |
|
| 330 |
// Use the canonical client ID (may differ from the raw input for discovered clients). |
| 331 |
$authorize_params['client_id'] = $client->get_client_id(); |
| 332 |
|
| 333 |
// These variables are used in the template. |
| 334 |
$current_user = \wp_get_current_user(); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable |
| 335 |
$scopes = Scope::validate( Scope::parse( $authorize_params['scope'] ) ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable |
| 336 |
|
| 337 |
// Build form action URL. |
| 338 |
// phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable |
| 339 |
$form_url = \add_query_arg( |
| 340 |
array_merge( array( 'action' => 'activitypub_authorize' ), $authorize_params ), |
| 341 |
\wp_login_url() |
| 342 |
); |
| 343 |
|
| 344 |
// Include the template. |
| 345 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-authorize.php'; // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- $authorize_params used in template. |
| 346 |
} |
| 347 |
|
| 348 |
/** |
| 349 |
* Process the OAuth authorization consent form submission. |
| 350 |
*/ |
| 351 |
private static function process_authorize_form() { |
| 352 |
// Verify nonce. |
| 353 |
if ( ! isset( $_POST['_wpnonce'] ) || ! \wp_verify_nonce( \sanitize_text_field( \wp_unslash( $_POST['_wpnonce'] ) ), 'activitypub_oauth_authorize' ) ) { |
| 354 |
$error_message = \__( 'Security check failed. Please try again.', 'activitypub' ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 355 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 356 |
exit; |
| 357 |
} |
| 358 |
|
| 359 |
// phpcs:disable WordPress.Security.NonceVerification.Missing -- Nonce verified above. |
| 360 |
$client_id = isset( $_POST['client_id'] ) ? \sanitize_text_field( \wp_unslash( $_POST['client_id'] ) ) : ''; |
| 361 |
$redirect_uri = isset( $_POST['redirect_uri'] ) ? Sanitize::redirect_uri( \wp_unslash( $_POST['redirect_uri'] ) ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- Sanitized via Sanitize::redirect_uri(). |
| 362 |
$scope = isset( $_POST['scope'] ) ? \sanitize_text_field( \wp_unslash( $_POST['scope'] ) ) : ''; |
| 363 |
$state = isset( $_POST['state'] ) ? \wp_unslash( $_POST['state'] ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- OAuth state is opaque; must be round-tripped exactly. |
| 364 |
$code_challenge = isset( $_POST['code_challenge'] ) ? \sanitize_text_field( \wp_unslash( $_POST['code_challenge'] ) ) : ''; |
| 365 |
$code_challenge_method = isset( $_POST['code_challenge_method'] ) ? \sanitize_text_field( \wp_unslash( $_POST['code_challenge_method'] ) ) : 'S256'; |
| 366 |
$approve = isset( $_POST['approve'] ); |
| 367 |
// phpcs:enable WordPress.Security.NonceVerification.Missing |
| 368 |
|
| 369 |
// Only S256 is supported; normalize empty/missing values and reject anything else. |
| 370 |
if ( empty( $code_challenge_method ) ) { |
| 371 |
$code_challenge_method = 'S256'; |
| 372 |
} elseif ( 'S256' !== $code_challenge_method ) { |
| 373 |
$error_message = \__( 'Only S256 is supported as PKCE code challenge method.', 'activitypub' ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 374 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 375 |
exit; |
| 376 |
} |
| 377 |
|
| 378 |
// Re-validate client and redirect URI (form fields could be tampered with). |
| 379 |
$client = Client::get( $client_id ); |
| 380 |
|
| 381 |
if ( \is_wp_error( $client ) ) { |
| 382 |
$error_message = $client->get_error_message(); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 383 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 384 |
exit; |
| 385 |
} |
| 386 |
|
| 387 |
if ( ! $client->is_valid_redirect_uri( $redirect_uri ) ) { |
| 388 |
$error_message = \__( 'Invalid redirect URI for this client.', 'activitypub' ); // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable -- Used in template. |
| 389 |
include ACTIVITYPUB_PLUGIN_DIR . 'templates/oauth-error.php'; |
| 390 |
exit; |
| 391 |
} |
| 392 |
|
| 393 |
// User denied authorization. |
| 394 |
if ( ! $approve ) { |
| 395 |
self::redirect_to_client( |
| 396 |
$redirect_uri, |
| 397 |
array( |
| 398 |
'error' => 'access_denied', |
| 399 |
'error_description' => 'The user denied the authorization request.', |
| 400 |
'state' => $state, |
| 401 |
) |
| 402 |
); |
| 403 |
} |
| 404 |
|
| 405 |
// Create authorization code. |
| 406 |
$scopes = Scope::validate( Scope::parse( $scope ) ); |
| 407 |
$code = Authorization_Code::create( |
| 408 |
\get_current_user_id(), |
| 409 |
$client_id, |
| 410 |
$redirect_uri, |
| 411 |
$scopes, |
| 412 |
$code_challenge, |
| 413 |
$code_challenge_method |
| 414 |
); |
| 415 |
|
| 416 |
if ( \is_wp_error( $code ) ) { |
| 417 |
self::redirect_to_client( |
| 418 |
$redirect_uri, |
| 419 |
array( |
| 420 |
'error' => 'server_error', |
| 421 |
'error_description' => $code->get_error_message(), |
| 422 |
'state' => $state, |
| 423 |
) |
| 424 |
); |
| 425 |
} |
| 426 |
|
| 427 |
self::redirect_to_client( |
| 428 |
$redirect_uri, |
| 429 |
array( |
| 430 |
'code' => $code, |
| 431 |
'state' => $state, |
| 432 |
) |
| 433 |
); |
| 434 |
} |
| 435 |
|
| 436 |
/** |
| 437 |
* Redirect to an OAuth client's redirect URI with query parameters. |
| 438 |
* |
| 439 |
* Uses a manual Location header because wp_redirect() strips custom |
| 440 |
* URI schemes used by native/mobile apps (RFC 8252 Section 7.1). |
| 441 |
* The URI is pre-validated against the registered client's redirect_uris |
| 442 |
* before this method is called. |
| 443 |
* |
| 444 |
* @param string $redirect_uri The client's redirect URI. |
| 445 |
* @param array $params Query parameters to append. |
| 446 |
*/ |
| 447 |
private static function redirect_to_client( $redirect_uri, $params ) { |
| 448 |
$url = Sanitize::redirect_uri( \add_query_arg( $params, $redirect_uri ) ); |
| 449 |
|
| 450 |
\nocache_headers(); |
| 451 |
header( 'Location: ' . $url, true, 303 ); |
| 452 |
exit; |
| 453 |
} |
| 454 |
} |
| 455 |
|
