From 0fd49bc023ed247a0a7424f50f141672f717cfad Mon Sep 17 00:00:00 2001
From: jedi <git@m.j3d1.de>
Date: Mon, 8 Apr 2024 20:54:29 +0200
Subject: [PATCH] add javascript dns resolver using DoH
---
frontend/src/dns.js | 50 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
create mode 100644 frontend/src/dns.js
diff --git a/frontend/src/dns.js b/frontend/src/dns.js
new file mode 100644
index 0000000..f07ea22
--- /dev/null
+++ b/frontend/src/dns.js
@@ -0,0 +1,50 @@
+import {query} from 'dns-query';
+
+function get_prefered_server() {
+ try {
+ const servers = JSON.parse(localStorage.getItem('dns-servers'));
+ if (servers && servers.length > 0) {
+ return servers;
+ }
+ } catch (e) {
+ console.error(e);
+ }
+ const request = new XMLHttpRequest();
+ request.open('GET', '/local/dns', false);
+ request.send(null);
+ if (request.status === 200) {
+ const servers = JSON.parse(request.responseText);
+ if (servers && servers.length > 0) {
+ return servers;
+ }
+ }
+ return ['1.1.1.1', '8.8.8.8'];
+}
+
+class FallBackResolver {
+ constructor() {
+ this._servers = get_prefered_server();
+ this._cache = JSON.parse(localStorage.getItem('dns-cache')) || {};
+ }
+
+ async query(domain, type) {
+ const key = domain + ':' + type;
+ if (key in this._cache && this._cache[key].time > Date.now() - 1000 * 60 * 60) {
+ const age_seconds = Math.ceil(Date.now() / 1000 - this._cache[key].time / 1000);
+ return [this._cache[key].data];
+ }
+ const result = await query(
+ {question: {type: type, name: domain}},
+ {
+ endpoints: this._servers,
+ }
+ )
+ if (result.answers.length === 0) throw new Error('No answer');
+ const first = result.answers[0];
+ this._cache[key] = {time: Date.now(), ...first}; // TODO hadle multiple answers
+ localStorage.setItem('dns-cache', JSON.stringify(this._cache));
+ return [first.data];
+ }
+}
+
+export default FallBackResolver;
\ No newline at end of file