56 lines
No EOL
1.8 KiB
JavaScript
56 lines
No EOL
1.8 KiB
JavaScript
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) {
|
|
try {
|
|
const servers = JSON.parse(request.responseText);
|
|
if (servers && servers.length > 0) {
|
|
return servers;
|
|
}
|
|
} catch (e) {
|
|
console.error(e);
|
|
}
|
|
}
|
|
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);
|
|
console.log('cache hit', key, this._cache[key].ttl - age_seconds);
|
|
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));
|
|
console.log('cache miss', key, first.ttl);
|
|
return [first.data];
|
|
}
|
|
}
|
|
|
|
export default FallBackResolver; |