Email MCP Server

import express from 'express'; import cors from 'cors'; import { createServer } from 'http'; import { spawn } from 'child_process'; import { Server } from '@modelcontextprotocol/sdk/server/index.js'; import { getVersion } from '../lib/getVersion.js'; import { WebSocketServerTransport } from '../server/websocket.js'; import { onSignals } from '../lib/onSignals.js'; import { serializeCorsOrigin } from '../lib/serializeCorsOrigin.js'; export async function stdioToWs(args) { const { stdioCmd, port, messagePath, logger, healthEndpoints, corsOrigin } = args; logger.info(` - port: ${port}`); logger.info(` - stdio: ${stdioCmd}`); logger.info(` - messagePath: ${messagePath}`); logger.info(` - CORS: ${corsOrigin ? `enabled (${serializeCorsOrigin({ corsOrigin })})` : 'disabled'}`); logger.info(` - Health endpoints: ${healthEndpoints.length ? healthEndpoints.join(', ') : '(none)'}`); let wsTransport = null; let child = null; let isReady = false; const cleanup = () => { if (wsTransport) { wsTransport.close().catch((err) => { logger.error(`Error stopping WebSocket server: ${err.message}`); }); } if (child) { child.kill(); } }; onSignals({ logger, cleanup, }); try { child = spawn(stdioCmd, { shell: true }); child.on('exit', (code, signal) => { logger.error(`Child exited: code=${code}, signal=${signal}`); cleanup(); process.exit(code ?? 1); }); const server = new Server({ name: 'supergateway', version: getVersion() }, { capabilities: {} }); // Handle child process output let buffer = ''; child.stdout.on('data', (chunk) => { buffer += chunk.toString('utf8'); const lines = buffer.split(/\r?\n/); buffer = lines.pop() ?? ''; lines.forEach((line) => { if (!line.trim()) return; try { const jsonMsg = JSON.parse(line); logger.info(`Child → WebSocket: ${JSON.stringify(jsonMsg)}`); // Broadcast to all connected clients wsTransport?.send(jsonMsg, jsonMsg.id).catch((err) => { logger.error('Failed to broadcast message:', err); }); } catch { logger.error(`Child non-JSON: ${line}`); } }); }); child.stderr.on('data', (chunk) => { logger.info(`Child stderr: ${chunk.toString('utf8')}`); }); const app = express(); if (corsOrigin) { app.use(cors({ origin: corsOrigin })); } for (const ep of healthEndpoints) { app.get(ep, (_req, res) => { if (child?.killed) { res.status(500).send('Child process has been killed'); } if (!isReady) { res.status(500).send('Server is not ready'); } res.send('ok'); }); } const httpServer = createServer(app); wsTransport = new WebSocketServerTransport({ path: messagePath, server: httpServer, }); await server.connect(wsTransport); wsTransport.onmessage = (msg) => { const line = JSON.stringify(msg); logger.info(`WebSocket → Child: ${line}`); child.stdin.write(line + '\n'); }; wsTransport.onconnection = (clientId) => { logger.info(`New WebSocket connection: ${clientId}`); }; wsTransport.ondisconnection = (clientId) => { logger.info(`WebSocket connection closed: ${clientId}`); }; wsTransport.onerror = (err) => { logger.error(`WebSocket error: ${err.message}`); }; isReady = true; httpServer.listen(port, () => { logger.info(`Listening on port ${port}`); logger.info(`WebSocket endpoint: ws://localhost:${port}${messagePath}`); }); } catch (err) { logger.error(`Failed to start: ${err.message}`); cleanup(); process.exit(1); } }