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<?php |
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/** |
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* The NotificationX MCP server — JSON-RPC 2.0 over HTTP. |
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* |
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* Handles the MCP method set (initialize, ping, tools/list, tools/call, |
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* notifications) and authenticates every call via a static pairing token or an |
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* OAuth 2.1 access token. On success it impersonates the granting admin so each |
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* ability's own capability checks run as that user; on failure it returns an |
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* RFC 9728 Bearer challenge so a client can discover how to authorize. |
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* |
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* @package NotificationX\MCP |
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*/ |
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|
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namespace NotificationX\MCP; |
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|
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use NotificationX\GetInstance; |
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|
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if ( ! defined( 'ABSPATH' ) ) { |
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exit; |
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} |
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|
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/** |
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* @method static Server get_instance( $args = null ) |
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*/ |
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class Server { |
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|
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use GetInstance; |
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|
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const PROTOCOL_VERSION = '2025-06-18'; |
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|
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// JSON-RPC error codes. |
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const PARSE_ERROR = -32700; |
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const INVALID_REQUEST = -32600; |
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const METHOD_NOT_FOUND = -32601; |
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const INVALID_PARAMS = -32602; |
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const INTERNAL_ERROR = -32603; |
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const UNAUTHORIZED = -32001; |
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|
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/** |
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* Handle an MCP request. Returns a WP_REST_Response so both the REST route |
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* and the pretty endpoint can emit it consistently. |
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* |
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* @param \WP_REST_Request $request Incoming request. |
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* @return \WP_REST_Response |
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*/ |
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public function handle( $request ) { |
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if ( ! Manager::get_instance()->is_enabled() ) { |
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return $this->response( array(), 403 ); |
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} |
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|
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$limiter = RateLimiter::get_instance(); |
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if ( $limiter->is_locked() ) { |
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$resp = $this->response( |
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$this->error_body( null, self::UNAUTHORIZED, __( 'Too many failed attempts. Try again later.', 'notificationx' ) ), |
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429 |
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); |
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$resp->header( 'Retry-After', (string) $limiter->retry_after() ); |
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return $this->with_challenge( $resp ); |
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} |
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|
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$token = $this->bearer_token( $request ); |
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|
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// No credential: normal OAuth opening probe. Challenge, do not penalise. |
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if ( '' === $token ) { |
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return $this->with_challenge( |
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$this->response( |
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$this->error_body( null, self::UNAUTHORIZED, __( 'Authentication required.', 'notificationx' ) ), |
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401 |
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) |
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); |
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} |
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|
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$auth = $this->authenticate( $token ); |
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if ( is_wp_error( $auth ) ) { |
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$limiter->record_failure(); |
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return $this->with_challenge( |
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$this->response( |
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$this->error_body( null, self::UNAUTHORIZED, $auth->get_error_message() ), |
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401 |
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) |
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); |
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} |
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$limiter->clear(); |
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|
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// Scope → read/write gating for this request. |
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Tools::get_instance()->set_read_only( ! empty( $auth['read_only'] ) ); |
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|
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$raw = $request->get_body(); |
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$decoded = json_decode( $raw, true ); |
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|
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if ( null === $decoded && JSON_ERROR_NONE !== json_last_error() ) { |
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return $this->response( $this->error_body( null, self::PARSE_ERROR, __( 'Parse error.', 'notificationx' ) ), 400 ); |
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} |
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|
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// Batch vs single. |
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if ( $this->is_batch( $decoded ) ) { |
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$out = array(); |
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foreach ( $decoded as $message ) { |
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$result = $this->dispatch( $message ); |
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if ( null !== $result ) { |
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$out[] = $result; |
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} |
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} |
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return empty( $out ) ? $this->response( null, 202 ) : $this->response( $out, 200 ); |
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} |
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|
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$result = $this->dispatch( is_array( $decoded ) ? $decoded : array() ); |
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return null === $result ? $this->response( null, 202 ) : $this->response( $result, 200 ); |
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} |
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|
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/** |
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* Dispatch a single JSON-RPC message. |
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* |
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* @param array $message Decoded message. |
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* @return array|null JSON-RPC response, or null for notifications. |
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*/ |
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protected function dispatch( $message ) { |
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$method = isset( $message['method'] ) ? $message['method'] : ''; |
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$id = isset( $message['id'] ) ? $message['id'] : null; |
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$params = isset( $message['params'] ) && is_array( $message['params'] ) ? $message['params'] : array(); |
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|
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// Notifications (no id) are acknowledged without a body. |
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if ( null === $id && 0 === strpos( (string) $method, 'notifications/' ) ) { |
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return null; |
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} |
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|
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switch ( $method ) { |
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case 'initialize': |
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return $this->result( $id, array( |
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'protocolVersion' => self::PROTOCOL_VERSION, |
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'capabilities' => array( |
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'tools' => array( 'listChanged' => false ), |
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), |
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'serverInfo' => array( |
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'name' => 'notificationx', |
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'version' => defined( 'NOTIFICATIONX_VERSION' ) ? NOTIFICATIONX_VERSION : '1.0.0', |
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), |
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) ); |
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|
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case 'ping': |
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return $this->result( $id, (object) array() ); |
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|
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case 'tools/list': |
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return $this->result( $id, array( 'tools' => Tools::get_instance()->list_tools() ) ); |
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|
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case 'tools/call': |
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return $this->call_tool( $id, $params ); |
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|
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default: |
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if ( null === $id ) { |
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return null; |
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} |
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return $this->error_body( $id, self::METHOD_NOT_FOUND, __( 'Method not found.', 'notificationx' ) ); |
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} |
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} |
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|
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/** |
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* Handle tools/call. |
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* |
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* @param mixed $id JSON-RPC id. |
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* @param array $params Params (name + arguments). |
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* @return array |
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*/ |
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protected function call_tool( $id, $params ) { |
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$name = isset( $params['name'] ) ? $params['name'] : ''; |
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$args = isset( $params['arguments'] ) && is_array( $params['arguments'] ) ? $params['arguments'] : array(); |
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|
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if ( '' === $name ) { |
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return $this->error_body( $id, self::INVALID_PARAMS, __( 'Missing tool name.', 'notificationx' ) ); |
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} |
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|
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$result = Tools::get_instance()->invoke( $name, $args ); |
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|
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// A tool-level error is returned as a *successful* JSON-RPC result with |
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// isError=true, so the assistant can read and react to the message. |
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if ( is_wp_error( $result ) ) { |
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return $this->result( $id, array( |
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'content' => array( |
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array( 'type' => 'text', 'text' => $result->get_error_message() ), |
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), |
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'isError' => true, |
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) ); |
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} |
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|
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return $this->result( $id, array( |
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'content' => array( |
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array( 'type' => 'text', 'text' => wp_json_encode( $result ) ), |
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), |
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'structuredContent' => $result, |
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'isError' => false, |
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) ); |
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} |
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|
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/* --------------------------------------------------------------------- */ |
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/* Authentication */ |
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/* --------------------------------------------------------------------- */ |
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|
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/** |
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* Authenticate a bearer token via pairing token or OAuth, then impersonate |
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* the granting admin. |
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* |
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* @param string $token Bearer token. |
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* @return array|\WP_Error { user_id, read_only } or error. |
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*/ |
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protected function authenticate( $token ) { |
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$pairing = Pairing::get_instance(); |
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if ( $pairing->is_connected() && $pairing->verify( $token ) ) { |
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$user = $this->impersonate( $pairing->user_id() ); |
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if ( is_wp_error( $user ) ) { |
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return $user; |
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} |
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$pairing->touch_last_used(); |
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return array( |
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'user_id' => $pairing->user_id(), |
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'read_only' => $pairing->is_read_only(), |
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); |
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} |
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|
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$grant = OAuth::get_instance()->validate_token( $token ); |
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if ( is_array( $grant ) ) { |
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$user = $this->impersonate( $grant['user_id'] ); |
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if ( is_wp_error( $user ) ) { |
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return $user; |
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} |
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return array( |
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'user_id' => $grant['user_id'], |
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'read_only' => OAuth::get_instance()->scope_is_read_only( isset( $grant['scope'] ) ? $grant['scope'] : '' ), |
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); |
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} |
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|
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return new \WP_Error( 'nx_mcp_unauthorized', __( 'Invalid or expired credentials.', 'notificationx' ) ); |
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} |
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|
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/** |
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* Become the granting user for the rest of the request. Refuses anyone who |
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* is not an administrator (a demoted/deleted admin's grants stop working). |
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* |
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* @param int $user_id User id. |
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* @return \WP_User|\WP_Error |
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*/ |
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protected function impersonate( $user_id ) { |
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$user = get_user_by( 'id', (int) $user_id ); |
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if ( ! $user || ! user_can( $user, 'manage_options' ) ) { |
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return new \WP_Error( 'nx_mcp_unauthorized', __( 'The account behind this connection can no longer manage NotificationX.', 'notificationx' ) ); |
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} |
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wp_set_current_user( $user->ID ); |
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return $user; |
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} |
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|
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/** |
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* Extract the bearer token from the Authorization header. |
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* |
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* @param \WP_REST_Request $request Request. |
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* @return string |
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*/ |
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protected function bearer_token( $request ) { |
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$header = $request->get_header( 'authorization' ); |
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if ( ! $header ) { |
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$header = $request->get_header( 'Authorization' ); |
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} |
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if ( $header && preg_match( '/Bearer\s+(.+)/i', $header, $m ) ) { |
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return trim( $m[1] ); |
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} |
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return ''; |
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} |
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|
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/* --------------------------------------------------------------------- */ |
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/* Response helpers */ |
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/* --------------------------------------------------------------------- */ |
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|
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/** |
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* Build a JSON-RPC success result. |
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* |
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* @param mixed $id Request id. |
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* @param mixed $result Result payload. |
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* @return array |
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*/ |
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protected function result( $id, $result ) { |
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return array( |
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'jsonrpc' => '2.0', |
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'id' => $id, |
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'result' => $result, |
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); |
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} |
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|
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/** |
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* Build a JSON-RPC error object. |
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* |
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* @param mixed $id Request id. |
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* @param int $code Error code. |
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* @param string $message Error message. |
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* @return array |
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*/ |
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protected function error_body( $id, $code, $message ) { |
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return array( |
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'jsonrpc' => '2.0', |
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'id' => $id, |
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'error' => array( |
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'code' => $code, |
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'message' => $message, |
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), |
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); |
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} |
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|
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/** |
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* Wrap a body in a WP_REST_Response and stamp the protocol header. |
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* |
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* @param mixed $body Response body. |
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* @param int $status HTTP status. |
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* @return \WP_REST_Response |
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*/ |
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protected function response( $body, $status = 200 ) { |
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$resp = new \WP_REST_Response( $body, $status ); |
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$resp->header( 'MCP-Protocol-Version', self::PROTOCOL_VERSION ); |
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$resp->header( 'Cache-Control', 'no-store' ); |
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return $resp; |
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} |
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|
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/** |
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* Add the RFC 9728 Bearer challenge header pointing at resource metadata. |
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* |
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* @param \WP_REST_Response $resp Response. |
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* @return \WP_REST_Response |
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*/ |
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protected function with_challenge( $resp ) { |
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$metadata_url = home_url( '/.well-known/oauth-protected-resource' ); |
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$resp->header( 'WWW-Authenticate', sprintf( 'Bearer resource_metadata="%s"', $metadata_url ) ); |
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return $resp; |
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} |
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|
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/** |
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* Whether a decoded payload is a JSON-RPC batch (a list of messages). |
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* |
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* @param mixed $decoded Decoded payload. |
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* @return bool |
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*/ |
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protected function is_batch( $decoded ) { |
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return is_array( $decoded ) && array() !== $decoded && array_keys( $decoded ) === range( 0, count( $decoded ) - 1 ); |
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} |
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} |
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|
