Enhance RDAP and WHOIS functionality with referral handling

Added support for following registrar WHOIS referrals with configurable hop limits. Introduced new options in LookupOptions for maximum referral hops and RDAP link handling. Updated README to reflect these changes and improved the lookupDomain function to utilize the new referral logic. Added utility functions for merging RDAP documents and extracting related links.

src/index.ts

@@ -2,16 +2,17 @@ import { toISO } from "./lib/dates";
 import { getDomainParts, isLikelyDomain } from "./lib/domain";
 import { getRdapBaseUrlsForTld } from "./rdap/bootstrap";
 import { fetchRdapDomain } from "./rdap/client";
+import { fetchAndMergeRdapRelated } from "./rdap/merge";
 import { normalizeRdap } from "./rdap/normalize";
 import type { DomainRecord, LookupOptions, LookupResult } from "./types";
 import { whoisQuery } from "./whois/client";
 import {
-  extractWhoisReferral,
   getIanaWhoisTextForTld,
   ianaWhoisServerForTld,
   parseIanaRegistrationInfoUrl,
 } from "./whois/discovery";
 import { normalizeWhois } from "./whois/normalize";
+import { followWhoisReferrals } from "./whois/referral";
 import { WHOIS_TLD_EXCEPTIONS } from "./whois/servers";
 
 /**
@@ -39,11 +40,16 @@ export async function lookupDomain(
         tried.push(base);
         try {
           const { json } = await fetchRdapDomain(domain, base, opts);
+          const rdapEnriched = await fetchAndMergeRdapRelated(
+            domain,
+            json,
+            opts,
+          );
           const record: DomainRecord = normalizeRdap(
             domain,
             tld,
-            json,
-            tried,
+            rdapEnriched.merged,
+            [...tried, ...rdapEnriched.serversTried],
             now,
             !!opts?.includeRaw,
           );
@@ -75,18 +81,8 @@ export async function lookupDomain(
         error: `No WHOIS server discovered for TLD '${tld}'. This registry may not publish public WHOIS over port 43.${hint}`,
       };
     }
-    // Query the TLD server first; if it returns a referral, we follow it below.
-    let res = await whoisQuery(whoisServer, domain, opts);
-    if (opts?.followWhoisReferral !== false) {
-      const referral = extractWhoisReferral(res.text);
-      if (referral && referral.toLowerCase() !== whoisServer.toLowerCase()) {
-        try {
-          res = await whoisQuery(referral, domain, opts);
-        } catch {
-          // keep original
-        }
-      }
-    }
+    // Query the TLD server first; optionally follow registrar referrals (multi-hop)
+    const res = await followWhoisReferrals(whoisServer, domain, opts);
 
     // If TLD registry returns no match and there was no referral, try multi-label public suffix candidates
     if (
@@ -102,10 +98,18 @@ export async function lookupDomain(
       for (const server of candidates) {
         try {
           const alt = await whoisQuery(server, domain, opts);
-          if (alt.text && !/error/i.test(alt.text)) {
-            res = alt;
-            break;
-          }
+          if (alt.text && !/error/i.test(alt.text))
+            return {
+              ok: true,
+              record: normalizeWhois(
+                domain,
+                tld,
+                alt.text,
+                alt.serverQueried,
+                now,
+                !!opts?.includeRaw,
+              ),
+            };
         } catch {
           // try next
         }