/**
* Aftermarket detection via nameserver fingerprints.
*
* Uses public DNS NS records to detect common parking/marketplace hosts.
* This is ToS-safe and does not require API keys.
*/
import { resolveNs } from 'node:dns/promises';
import type { DomainResult } from '../types.js';
import { config } from '../config.js';
import { logger } from '../utils/logger.js';
import { TtlCache } from '../utils/cache.js';
type AftermarketListing = DomainResult['aftermarket'];
type NsFingerprint = {
source: string;
type: 'aftermarket' | 'auction' | 'premium';
nameservers: string[];
url?: (domain: string) => string;
note?: string;
};
const NS_TIMEOUT_MS = config.aftermarket.nsTimeoutMs;
const nsCache = new TtlCache<AftermarketListing | null>(
config.aftermarket.nsCacheTtl,
);
const NS_FINGERPRINTS: NsFingerprint[] = [
{
source: 'sedo',
type: 'aftermarket',
nameservers: ['ns1.sedoparking.com', 'ns2.sedoparking.com'],
url: (domain) =>
`https://sedo.com/search/?keyword=${encodeURIComponent(domain)}`,
note: 'Nameserver indicates Sedo parking. Verify listing on Sedo.',
},
{
source: 'dan',
type: 'aftermarket',
nameservers: ['ns1.dan.com', 'ns2.dan.com'],
url: (domain) => `https://dan.com/buy-domain/${encodeURIComponent(domain)}`,
note: 'Nameserver indicates Dan parking. Verify listing on Dan.',
},
{
source: 'afternic',
type: 'aftermarket',
nameservers: ['ns1.afternic.com', 'ns2.afternic.com'],
url: (domain) =>
`https://www.afternic.com/forsale/${encodeURIComponent(domain)}`,
note: 'Nameserver indicates Afternic parking. Verify listing on Afternic.',
},
];
async function resolveNsWithTimeout(domain: string): Promise<string[]> {
const timeout = new Promise<string[]>((_, reject) => {
setTimeout(() => reject(new Error('ns_timeout')), NS_TIMEOUT_MS);
});
return Promise.race([resolveNs(domain), timeout]);
}
export async function lookupAftermarketByNameserver(
domain: string,
): Promise<AftermarketListing | null> {
if (!config.aftermarket.nsEnabled) {
return null;
}
const key = domain.toLowerCase();
const cached = nsCache.get(key);
if (cached !== undefined) {
return cached;
}
try {
const nameservers = (await resolveNsWithTimeout(domain)).map((ns) =>
ns.toLowerCase(),
);
for (const fingerprint of NS_FINGERPRINTS) {
const matches = fingerprint.nameservers.every((ns) =>
nameservers.includes(ns),
);
if (!matches) {
continue;
}
const listing: AftermarketListing = {
type: fingerprint.type,
price: null,
currency: null,
source: fingerprint.source,
url: fingerprint.url ? fingerprint.url(domain) : undefined,
note: fingerprint.note,
};
nsCache.set(key, listing);
return listing;
}
} catch (error) {
logger.debug('Nameserver aftermarket lookup failed', {
domain,
error: error instanceof Error ? error.message : String(error),
});
}
nsCache.set(key, null);
return null;
}
