MCP Server Boilerplate

import { Request } from 'express'; import { isIP } from 'net'; /** * Parse comma-separated IPs and return the first valid one */ const parseIPList = (ipString: string): string | null => { if (!ipString || ipString.trim() === '') { return null; } const ips = ipString.split(',').map(ip => ip.trim()); for (const ip of ips) { if (isIP(ip)) { return ip; } } return null; }; /** * Process a header value (string or array) and return the first valid IP */ const processHeaderValue = (headerValue: string | string[]): string | null => { if (typeof headerValue === 'string' && headerValue.length > 0) { return parseIPList(headerValue); } if (Array.isArray(headerValue) && headerValue.length > 0) { for (const value of headerValue) { if (typeof value === 'string' && value.length > 0) { const ip = parseIPList(value); if (ip !== null) return ip; } } } return null; }; export const getIPAddress = (req: Request): string => { // Headers to check in order of priority const headerPriority = [ 'cf-connecting-ip', // Cloudflare 'x-real-ip', // Nginx 'x-forwarded-for', // Standard proxy header 'x-client-ip', // Apache 'x-forwarded', // RFC 7239 'forwarded-for', // RFC 7239 'forwarded', // RFC 7239 'x-cluster-client-ip', // Cluster environments 'x-original-forwarded-for', // Some CDNs 'true-client-ip', // Akamai, CloudFlare ]; for (const header of headerPriority) { const headerValue = req.headers[header]; if (headerValue !== undefined && headerValue !== '') { const ip = processHeaderValue(headerValue); if (ip !== null) return ip; } } // Final fallback return 'unknown'; };