@multiformats/dns
Version:
Resolve DNS queries with browser fallback
86 lines • 3.23 kB
JavaScript
/* eslint-env browser */
import { Buffer } from 'buffer';
import dnsPacket from 'dns-packet';
import PQueue from 'p-queue';
import { CustomProgressEvent } from 'progress-events';
import { toString as uint8ArrayToString } from 'uint8arrays/to-string';
import { RecordType } from '../index.js';
import { getTypes } from '../utils/get-types.js';
import { toDNSResponse } from '../utils/to-dns-response.js';
/**
* Browsers limit concurrent connections per host (~6), we don't want to exhaust
* the limit so this value controls how many DNS queries can be in flight at
* once.
*/
export const DEFAULT_QUERY_CONCURRENCY = 4;
function toType(type) {
if (type === RecordType.A) {
return 'A';
}
if (type === RecordType.AAAA) {
return 'AAAA';
}
if (type === RecordType.TXT) {
return 'TXT';
}
if (type === RecordType.CNAME) {
return 'CNAME';
}
throw new Error('Unsupported DNS record type');
}
/**
* Uses the RFC 1035 'application/dns-message' content-type to resolve DNS
* queries.
*
* This resolver needs more dependencies than the non-standard
* DNS-JSON-over-HTTPS resolver so can result in a larger bundle size and
* consequently is not preferred for browser use.
*
* @see https://datatracker.ietf.org/doc/html/rfc1035
* @see https://developers.cloudflare.com/1.1.1.1/encryption/dns-over-https/make-api-requests/dns-wireformat/
* @see https://github.com/curl/curl/wiki/DNS-over-HTTPS#publicly-available-servers
* @see https://dnsprivacy.org/public_resolvers/
*/
export function dnsOverHttps(url, init = {}) {
const httpQueue = new PQueue({
concurrency: init.queryConcurrency ?? DEFAULT_QUERY_CONCURRENCY
});
return async (fqdn, options = {}) => {
const types = getTypes(options.types);
const dnsQuery = dnsPacket.encode({
type: 'query',
id: 0,
flags: dnsPacket.RECURSION_DESIRED,
questions: types.map(type => ({
type: toType(type),
name: fqdn
}))
});
const searchParams = new URLSearchParams();
searchParams.set('dns', uint8ArrayToString(dnsQuery, 'base64url'));
options.onProgress?.(new CustomProgressEvent('dns:query', { detail: fqdn }));
// query DNS over HTTPS server
const response = await httpQueue.add(async () => {
const res = await fetch(`${url}?${searchParams}`, {
headers: {
accept: 'application/dns-message'
},
signal: options.signal
});
if (res.status !== 200) {
throw new Error(`Unexpected HTTP status: ${res.status} - ${res.statusText}`);
}
const buf = await res.arrayBuffer();
const response = toDNSResponse(dnsPacket.decode(Buffer.from(buf)));
options.onProgress?.(new CustomProgressEvent('dns:response', { detail: response }));
return response;
}, {
signal: options.signal
});
if (response == null) {
throw new Error('No DNS response received');
}
return response;
};
}
//# sourceMappingURL=dns-over-https.js.map