metasync / wp-mcp-server / class-mcp-json-rpc-handler.php

class-mcp-json-rpc-handler.php in Search Atlas SEO – OTTO AI SEO Automation for WordPress 2.7.1, at wp-mcp-server/class-mcp-json-rpc-handler.php

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1	<?php
2	/**
3	* MCP JSON-RPC 2.0 Handler
4	*
5	* Handles parsing, validation, and routing of JSON-RPC 2.0 requests
6	* according to the Model Context Protocol specification.
7	*
8	* @package MetaSync
9	* @subpackage MCP_Server
10	*/
11
12	if (!defined('ABSPATH')) {
13	exit;
14	}
15
16	class MCP_JSON_RPC_Handler {
17
18	/**
19	* JSON-RPC version
20	*/
21	const JSONRPC_VERSION = '2.0';
22
23	/**
24	* Error codes (JSON-RPC 2.0 standard + custom)
25	*/
26	const ERROR_PARSE_ERROR = -32700;
27	const ERROR_INVALID_REQUEST = -32600;
28	const ERROR_METHOD_NOT_FOUND = -32601;
29	const ERROR_INVALID_PARAMS = -32602;
30	const ERROR_INTERNAL_ERROR = -32603;
31	const ERROR_SERVER_ERROR = -32000;
32	const ERROR_RATE_LIMITED = -32029;
33
34	/**
35	* Method handlers
36	*
37	* @var array
38	*/
39	private $handlers = [];
40
41	/**
42	* Constructor
43	*/
44	public function __construct() {
45	// Register default handlers
46	$this->register_handler('initialize', [$this, 'handle_initialize']);
47	$this->register_handler('ping', [$this, 'handle_ping']);
48	}
49
50	/**
51	* Register a method handler
52	*
53	* @param string $method Method name
54	* @param callable $callback Handler callback
55	*/
56	public function register_handler($method, $callback) {
57	if (!is_callable($callback)) {
58	throw new InvalidArgumentException("Handler for method '{$method}' must be callable");
59	}
60	$this->handlers[$method] = $callback;
61	}
62
63	/**
64	* Handle incoming JSON-RPC request
65	*
66	* @param string $request_body Raw request body
67	* @return array\|null Response array, or null for a notification
68	*/
69	public function handle_request($request_body) {
70	// Parse JSON
71	$request = json_decode($request_body, true);
72
73	if (json_last_error() !== JSON_ERROR_NONE) {
74	return $this->error_response(null, self::ERROR_PARSE_ERROR, 'Parse error');
75	}
76
77	// Validate request structure
78	if (!$this->validate_request($request)) {
79	return $this->error_response(
80	isset($request['id']) ? $request['id'] : null,
81	self::ERROR_INVALID_REQUEST,
82	'Invalid Request'
83	);
84	}
85
86	$method = $request['method'];
87	$params = isset($request['params']) ? $request['params'] : [];
88	$id = isset($request['id']) ? $request['id'] : null;
89
90	// Check if handler exists
91	if (!isset($this->handlers[$method])) {
92	if (!array_key_exists('id', $request)) {
93	return null;
94	}
95
96	return $this->error_response($id, self::ERROR_METHOD_NOT_FOUND, "Method not found: {$method}");
97	}
98
99	try {
100	// Call handler
101	$result = call_user_func($this->handlers[$method], $params);
102	if (!array_key_exists('id', $request)) {
103	return null;
104	}
105
106	return $this->success_response($id, $result);
107	} catch (InvalidArgumentException $e) {
108	if (!array_key_exists('id', $request)) {
109	return null;
110	}
111
112	return $this->error_response($id, self::ERROR_INVALID_PARAMS, $e->getMessage());
113	} catch (Exception $e) {
114	// Log error
115	error_log('MCP JSON-RPC Error: ' . $e->getMessage()); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log -- genuine failure path, bounded, no secrets
116	if (!array_key_exists('id', $request)) {
117	return null;
118	}
119
120	return $this->error_response($id, self::ERROR_INTERNAL_ERROR, $e->getMessage());
121	}
122	}
123
124	/**
125	* Validate JSON-RPC request structure
126	*
127	* @param mixed $request Request data
128	* @return bool
129	*/
130	private function validate_request($request) {
131	if (!is_array($request)) {
132	return false;
133	}
134
135	// Must have jsonrpc, method
136	if (!isset($request['jsonrpc']) \|\| $request['jsonrpc'] !== self::JSONRPC_VERSION) {
137	return false;
138	}
139
140	if (!isset($request['method']) \|\| !is_string($request['method'])) {
141	return false;
142	}
143
144	// Params are optional but must be array or object if present
145	if (isset($request['params']) && !is_array($request['params'])) {
146	return false;
147	}
148
149	return true;
150	}
151
152	/**
153	* Create success response
154	*
155	* @param mixed $id Request ID
156	* @param mixed $result Result data
157	* @return array
158	*/
159	public function success_response($id, $result) {
160	return [
161	'jsonrpc' => self::JSONRPC_VERSION,
162	'id' => $id,
163	'result' => $result
164	];
165	}
166
167	/**
168	* Create error response
169	*
170	* @param mixed $id Request ID
171	* @param int $code Error code
172	* @param string $message Error message
173	* @param mixed $data Optional error data
174	* @return array
175	*/
176	public function error_response($id, $code, $message, $data = null) {
177	$error = [
178	'code' => $code,
179	'message' => $message
180	];
181
182	if ($data !== null) {
183	$error['data'] = $data;
184	}
185
186	return [
187	'jsonrpc' => self::JSONRPC_VERSION,
188	'id' => $id,
189	'error' => $error
190	];
191	}
192
193	/**
194	* Handle initialize method
195	*
196	* @param array $params Request parameters
197	* @return array
198	*/
199	private function handle_initialize($params) {
200	return [
201	'protocolVersion' => '2024-11-05',
202	'capabilities' => [
203	'tools' => [
204	'list' => true,
205	'call' => true
206	]
207	],
208	'serverInfo' => [
209	'name' => 'metasync-wordpress-mcp',
210	'version' => METASYNC_VERSION
211	]
212	];
213	}
214
215	/**
216	* Handle ping method
217	*
218	* @param array $params Request parameters
219	* @return array
220	*/
221	private function handle_ping($params) {
222	return ['status' => 'ok'];
223	}
224	}
225