server/isURLLocal.ts

Functions to determine if a URL or hostname refers to a local or loopback address, with validation.

// Source: https://github.com/ruvnet/ruflo | License: MIT | Copyright 2024-2026 ruvnet
// Provided via justclaw.it.com; keep this notice with the code.
import { Address6, Address4 } from "ip-address";
import dns from "node:dns";
import { isIP } from "node:net";

const dnsLookup = (hostname: string): Promise<{ address: string; family: number }> => {
	return new Promise((resolve, reject) => {
		dns.lookup(hostname, (err, address, family) => {
			if (err) return reject(err);
			resolve({ address, family });
		});
	});
};

function assertValidHostname(hostname: string): void {
	if (!hostname || hostname.length > 253) {
		throw new Error("Invalid hostname");
	}

	const labels = hostname.split(".");

	for (const label of labels) {
		if (!label || label.length > 63) {
			throw new Error("Invalid 

... (truncated -- full source via MCP)