feat: retrieve peers from all passed enrtree URLs

Order retrieval is random, but it attemps to retrieve from all ENR trees.

packages/discovery/src/dns/dns.ts

@@ -1,6 +1,6 @@
 import { ENR, EnrDecoder } from "@waku/enr";
 import type { DnsClient, IEnr, SearchContext } from "@waku/interfaces";
-import { Logger } from "@waku/utils";
+import { Logger, shuffle } from "@waku/utils";
 
 import { DnsOverHttps } from "./dns_over_https.js";
 import { ENRTree } from "./enrtree.js";
@@ -27,19 +27,23 @@ export class DnsNodeDiscovery {
   }
 
   /**
-   * {@inheritDoc getPeers}
+   * Retrieve the next peers from the passed [[enrTreeUrls]],
    */
   public async *getNextPeer(enrTreeUrls: string[]): AsyncGenerator<IEnr> {
-    const networkIndex = Math.floor(Math.random() * enrTreeUrls.length);
-    const { publicKey, domain } = ENRTree.parseTree(enrTreeUrls[networkIndex]);
-    const context: SearchContext = {
-      domain,
-      publicKey,
-      visits: {}
-    };
+    // Shuffle the ENR Trees so that not all clients connect to same nodes first.
+    for (const enrTreeUrl of shuffle(enrTreeUrls)) {
+      const { publicKey, domain } = ENRTree.parseTree(enrTreeUrl);
+      const context: SearchContext = {
+        domain,
+        publicKey,
+        visits: {}
+      };
 
-    for await (const peer of fetchNodes(() => this._search(domain, context))) {
-      yield peer;
+      for await (const peer of fetchNodes(() =>
+        this._search(domain, context)
+      )) {
+        yield peer;
+      }
     }
   }
 
@@ -113,7 +117,7 @@ export class DnsNodeDiscovery {
       throw new Error("Received empty result array while fetching TXT record");
     if (!response[0].length) throw new Error("Received empty TXT record");
 
-    // Branch entries can be an array of strings of comma delimited subdomains, with
+    // Branch entries can be an array of strings of comma-delimited subdomains, with
     // some subdomain strings split across the array elements
     const result = response.join("");
 

packages/tests/tests/dns-peer-discovery.spec.ts

@@ -77,7 +77,7 @@ describe("DNS Node Discovery [live data]", function () {
     expect(dnsPeers).to.gte(minQuantityExpected);
   });
 
-  it(`should retrieve ${maxQuantity} multiaddrs for test.waku.nodes.status.im`, async function () {
+  it(`should retrieve ${maxQuantity} multiaddrs for sandbox.waku.nodes.status.im`, async function () {
     if (process.env.CI) this.skip();
 
     this.timeout(10000);
@@ -102,6 +102,34 @@ describe("DNS Node Discovery [live data]", function () {
       seen.push(ma!.toString());
     }
   });
+
+  it(`should retrieve all multiaddrs when several ENR Tree URLs are passed`, async function () {
+    if (process.env.CI) this.skip();
+
+    this.timeout(10000);
+    // Google's dns server address. Needs to be set explicitly to run in CI
+    const dnsNodeDiscovery = await DnsNodeDiscovery.dnsOverHttp();
+
+    const peers = [];
+    for await (const peer of dnsNodeDiscovery.getNextPeer([
+      enrTree["SANDBOX"],
+      enrTree["TEST"]
+    ])) {
+      peers.push(peer);
+    }
+
+    expect(peers.length).to.eq(6);
+
+    const multiaddrs = peers.map((peer) => peer.multiaddrs).flat();
+
+    const seen: string[] = [];
+    for (const ma of multiaddrs) {
+      expect(ma).to.not.be.undefined;
+      expect(seen).to.not.include(ma!.toString());
+      seen.push(ma!.toString());
+    }
+  });
+
   it("passes more than one ENR URLs and attempts connection", async function () {
     if (process.env.CI) this.skip();
     this.timeout(30_000);

packages/utils/src/common/random_subset.ts

@@ -12,7 +12,7 @@ export function getPseudoRandomSubset<T>(
   return shuffle(values).slice(0, wantedNumber);
 }
 
-function shuffle<T>(arr: T[]): T[] {
+export function shuffle<T>(arr: T[]): T[] {
   if (arr.length <= 1) {
     return arr;
   }