mcp-server.js•4.36 kB
import logger from './logger.js';
import net from 'net';
import MCPHandler from './mcp-handler.js'; // Added .js extension
let instance = null;
class MCPServer {
constructor() {
if (instance) {
return instance;
}
this.mcpHandler = new MCPHandler();
this.server = null;
this.connections = new Set();
this.port = null;
instance = this;
}
start(port) {
if (this.server) {
logger.info('MCP server already running');
return this.server;
}
// Allow port override via env or CLI, or use random port if not specified
let chosenPort = port || process.env.MCP_PORT || 0;
this.server = net.createServer((socket) => {
logger.info('MCP client connected');
this.connections.add(socket);
let buffer = '';
socket.on('data', async (data) => {
const raw = data.toString();
logger.info('[MCP DEBUG] Raw data received:', JSON.stringify(raw));
buffer += raw;
// Process complete JSON messages (newline-delimited)
let jsonEndPos = 0;
let parsePos = 0;
while ((jsonEndPos = buffer.indexOf('\n', parsePos)) !== -1) {
// Extract a complete line which should contain a JSON message
const jsonString = buffer.substring(parsePos, jsonEndPos).trim();
parsePos = jsonEndPos + 1;
if (!jsonString) continue; // Ignore empty lines
try {
// Defensive: Only parse if it looks like JSON
if (!jsonString.startsWith('{') || !jsonString.endsWith('}')) {
logger.warn('[MCP DEBUG] Skipping non-JSON line:', jsonString);
continue;
}
const message = JSON.parse(jsonString);
logger.info('MCP received message type:', message.method);
// Process the message
const response = await this.mcpHandler.handleMessage(message);
// Send the response
if (response) {
const responseStr = JSON.stringify(response) + '\n';
logger.info('[MCP DEBUG] Sending response:', responseStr);
// Send as LSP Content-Length header framing for maximum compatibility
const jsonBuffer = Buffer.from(responseStr, 'utf8');
const header = `Content-Length: ${jsonBuffer.length}\r\n\r\n`;
socket.write(header, 'utf8');
socket.write(jsonBuffer);
}
} catch (error) {
logger.error('Error processing MCP message:', error.message);
// Send error response
const errorResponse = {
jsonrpc: "2.0",
error: { code: -32700, message: "Parse error" },
id: null
};
const errorStr = JSON.stringify(errorResponse) + '\n';
logger.info('[MCP DEBUG] Sending error response:', errorStr);
// Send as LSP Content-Length header framing for maximum compatibility
const errBuffer = Buffer.from(errorStr, 'utf8');
const errHeader = `Content-Length: ${errBuffer.length}\r\n\r\n`;
socket.write(errHeader, 'utf8');
socket.write(errBuffer);
}
}
// Keep any remaining incomplete data
buffer = buffer.substring(parsePos);
});
socket.on('end', () => {
logger.info('MCP client disconnected');
this.connections.delete(socket);
});
socket.on('error', (err) => {
logger.error('MCP socket error:', err.message);
this.connections.delete(socket);
});
});
this.server.listen(chosenPort, () => {
this.port = this.server.address().port;
logger.info(`MCP Server listening on port ${this.port}`);
// Optionally write port to a file or env for test clients
});
this.server.on('error', (err) => {
logger.error('MCP server error:', err.message);
});
return this.server;
}
getPort() {
return this.port;
}
stop() {
if (this.server) {
// Close all active connections
for (const socket of this.connections) {
socket.destroy();
}
this.connections.clear();
// Close the server
this.server.close();
this.server = null;
this.port = null;
logger.info('MCP server stopped');
}
}
}
export default new MCPServer();
