*Add new core dht plugin that allows joining a DHT topic and getting the peers of a given topic

src/modules/plugin.ts

@@ -10,6 +10,7 @@ import type { Logger } from "pino";
 import { getHDKey, getSeed } from "../lib/seed.js";
 import pluginRpc from "./plugins/rpc";
 import pluginCore from "./plugins/core";
+import pluginDht from "./plugins/dht";
 import type Config from "@lumeweb/cfg";
 import EventEmitter2 from "eventemitter2";
 import log from "../log.js";
@@ -229,6 +230,7 @@ export async function loadPlugins() {
 
   apiManager.loadPluginInstance(pluginCore);
   apiManager.loadPluginInstance(pluginRpc);
+  apiManager.loadPluginInstance(pluginDht);
 
   for (const plugin of [...new Set(config.array("plugins", []))] as []) {
     await apiManager.loadPlugin(plugin);

src/modules/plugins/dht.ts

@@ -0,0 +1,27 @@
+import { Plugin, PluginAPI } from "@lumeweb/relay-types";
+import { getRpcServer } from "../rpc/server";
+import b4a from "b4a";
+
+const plugin: Plugin = {
+  name: "dht",
+  async plugin(api: PluginAPI): Promise<void> {
+    api.registerMethod("join_topic", {
+      cacheable: false,
+      async handler(topic: string): Promise<void> {
+        if (!api.swarm._discovery.has(topic)) {
+          api.swarm.join(topic);
+        }
+      },
+    });
+    api.registerMethod("get_topic_peers", {
+      cacheable: false,
+      async handler(topic: string): Promise<string[]> {
+        return [...api.swarm.peers.values()]
+          .filter((peerInfo) => peerInfo._seenTopics.has(topic))
+          .map((peerInfo) => b4a.from(peerInfo.publicKey).toString());
+      },
+    });
+  },
+};
+
+export default plugin;