@kanadi/core/src/utils/fingerprint.server.ts

Multi-Layer CAPTCHA Framework with customizable validators and challenge bundles

import { createHash } from "crypto";

export interface ServerFingerprintData {
	ip: string;
	userAgent: string;
	acceptLanguage?: string;
	acceptEncoding?: string;
	connection?: string;
	headers: Record<string, string>;
}

function normalizeIP(ip: string): string {
	if (ip.startsWith("::ffff:")) {
		return ip.substring(7);
	}
	return ip;
}

function parseUserAgent(userAgent: string): string {
	const parts = userAgent.split(/[\s/()]+/);
	return parts
		.filter((p) => p && p.length > 2)
		.slice(0, 5)
		.join("|");
}

export function generateServerFingerprint(data: {
	ip: string;
	userAgent?: string;
	headers?: Record<string, string | string[] | undefined>;
}): { fingerprint: string; data: ServerFingerprintData } {
	const normalizedIP = normalizeIP(data.ip);
	const userAgent = data.userAgent || "";
	const headers = data.headers || {};

	const getHeader = (key: string): string => {
		const value = headers[key.toLowerCase()];
		if (Array.isArray(value)) return value[0] || "";
		return value || "";
	};

	const fingerprintData: ServerFingerprintData = {
		ip: normalizedIP,
		userAgent: parseUserAgent(userAgent),
		acceptLanguage: getHeader("accept-language"),
		acceptEncoding: getHeader("accept-encoding"),
		connection: getHeader("connection"),
		headers: {
			"accept-language": getHeader("accept-language"),
			"accept-encoding": getHeader("accept-encoding"),
			"sec-ch-ua": getHeader("sec-ch-ua"),
			"sec-ch-ua-mobile": getHeader("sec-ch-ua-mobile"),
			"sec-ch-ua-platform": getHeader("sec-ch-ua-platform"),
		},
	};

	const fingerprintString = JSON.stringify(fingerprintData);
	const fingerprint = createHash("sha256")
		.update(fingerprintString)
		.digest("hex");

	return { fingerprint, data: fingerprintData };
}

export function combineFingerprints(
	clientFingerprint: string,
	serverFingerprint: string,
): string {
	const combined = `${clientFingerprint}:${serverFingerprint}`;
	return createHash("sha256").update(combined).digest("hex");
}