lukeburns / bns

Recursive DNS server and resolver for node.js

bns

DNS library, server, and validating recursive resolver for node.js, in pure javascript.

Server Usage

Base Server

const bns = require('bns');
const {wire, Server} = bns;

const server = new Server({
  // Allow queries over TCP.
  tcp: true,
  // Maximum concurrent TCP connections.
  maxConnections: 20,
  // Add EDNS0 OPT record in responses.
  edns: true,
  // Set the UDP buffer size to 4096.
  ednsSize: 4096,
  // Add EDNS0 DO bit in responses.
  dnssec: true
});

server.on('query', (req, res, rinfo) => {
  const [question] = req.question;

  // Log all requests (dig format).
  console.log('Incoming request:');
  console.log(req.toString());

  // Respond with an A record (see lib/wire.js).
  if (question.name === 'example.com.') {
    const rr = new wire.Record();

    rr.name = 'example.com.';
    rr.type = wire.types.A;
    rr.ttl = 3600;
    rr.data = new wire.ARecord();
    rr.data.address = '127.0.0.1';

    res.answer.push(rr);
    res.send();

    return;
  }

  // Not found!
  res.code = wire.codes.NXDOMAIN;
  res.send();
});

server.bind(5300, '127.0.0.1');

Authoritative Server

const bns = require('bns');
const {AuthServer} = bns;

const server = new AuthServer({
  tcp: true,
  edns: true,
  dnssec: true
});

// Tell bns which zone we're serving.
server.setOrigin('myzone.');

// Parse our zone file.
server.setFile('/path/to/my/zonefile.zone');

server.on('query', (req, res, rinfo) => {
  // Log all requests (dig format).
  console.log('Incoming request:');
  console.log(req.toString());
});

server.bind(5300, '127.0.0.1');

Recursive Server

const bns = require('bns');
const {RecursiveServer} = bns;

const server = new RecursiveServer({
  tcp: true,
  inet6: true,
  edns: true,
  dnssec: true
});

// Root Hints (see lib/hints.js):
server.hints.setDefault();

// Custom hints:
// server.hints.fromFile('/path/to/our/custom.hints');

server.on('query', (req, res, rinfo) => {
  // Log all requests (dig format).
  console.log('Incoming request:');
  console.log(req.toString());
});

server.bind(5300, '127.0.0.1');

Now you can have a local recursive resolver instead of relying on google's or your ISP's public DNS!

Resolver Usage

Stub Resolver

const bns = require('bns');
const {StubResolver} = bns;

const resolver = new StubResolver({
  tcp: true,
  inet6: true,
  edns: true,
  dnssec: true
});

// Like /etc/hosts (see lib/hosts.js).
resolver.setHosts([
  ['localhost.', '127.0.0.1'],
  ['localhost.', '::1']
]);

// Like /etc/resolv.conf (see lib/resolvconf.js).
resolver.setServers(['8.8.8.8', '8.8.4.4']);

resolver.on('log', (...args) => console.log(...args));

await resolver.open();

const res = await resolver.lookup('google.com.', 'ANY');
console.log(res.toString());

Recursive Resolver

const bns = require('bns');
const {RecursiveResolver} = bns;

const resolver = new RecursiveResolver({
  tcp: true,
  inet6: true,
  edns: true,
  dnssec: true
});

// Use default root hints and trust
// anchors (see lib/hints.js).
resolver.hints.setDefault();

resolver.on('log', (...args) => console.log(...args));

await resolver.open();

const res = await resolver.lookup('google.com.', 'ANY');
console.log(res.toString());

Node.js API Usage

BNS has a module which mimics the node.js API.

const {dns} = require('bns');

console.log(await dns.resolve6('google.com'));

The recursive resolver can also mimic the node.js API!

const {rdns} = require('bns');

console.log(await rdns.resolve6('google.com'));

CLI Usage

named.js

A quick way to setup a server.

Running an authoritative server is as simple as:

$ named.js @:: -p 5300 -z ~/myzonefile.zone myzone. +edns

dig.js

BNS comes with a reimplementation of dig.

$ dig.js --recursive www.ietf.org +dnssec +debug
Querying www.ietf.org./A.
Switching authority: (hints.local.)
Switching zone: [.]
Querying server: 2001:500:12::d0d (38470)
Verifying zone change to [.]
Checking signatures...
Querying server: 199.7.83.42 (14617)
Validated DNSSEC signatures.
Switching authority: (b2.org.afilias-nst.org.)
Switching zone: [.->org.]
Querying server: 199.19.54.1 (4434)
Verifying zone change to [org.]
Checking signatures...
Querying server: 199.19.54.1 (42051)
Validated DNSSEC signatures.
Looking up NS: ns1.ams1.afilias-nst.info.
Looking up IPv6 nameserver for ns1.ams1.afilias-nst.info....
Querying ns1.ams1.afilias-nst.info./AAAA.
Switching authority: (hints.local.)
Switching zone: [.]
Querying server: 192.33.4.12 (26984)
Verifying zone change to [.]
Checking signatures...
Cache hit for ./DNSKEY.
Validated DNSSEC signatures.
Switching authority: (b2.info.afilias-nst.org.)
Switching zone: [.->info.]
Querying server: 2001:500:1b::1 (19432)
Verifying zone change to [info.]
Checking signatures...
Querying server: 2001:500:1c::1 (48266)
Validated DNSSEC signatures.
Validated NSEC3 delegation.
Switching authority: (d0.dig.afilias-nst.info.)
Switching zone: [info.->afilias-nst.info.]
Trust chain broken due to zone change.
Querying server: 2a01:8840:7::1 (14155)
Traversed zones: ., info., afilias-nst.info. for ns1.ams1.afilias-nst.info./AAAA.
IPv6 nameserver lookup failed: No authority address.
Looking up IPv4 nameserver for ns1.ams1.afilias-nst.info....
Querying ns1.ams1.afilias-nst.info./A.
Switching authority: (hints.local.)
Switching zone: [.]
Querying server: 198.97.190.53 (56951)
Verifying zone change to [.]
Checking signatures...
Cache hit for ./DNSKEY.
Validated DNSSEC signatures.
Switching authority: (a0.info.afilias-nst.info.)
Switching zone: [.->info.]
Querying server: 2001:500:1b::1 (17528)
Verifying zone change to [info.]
Checking signatures...
Cache hit for info./DNSKEY.
Validated DNSSEC signatures.
Validated NSEC3 delegation.
Switching authority: (c0.dig.afilias-nst.info.)
Switching zone: [info.->afilias-nst.info.]
Trust chain broken due to zone change.
Querying server: 2a01:8840:9::1 (29803)
Traversed zones: ., info., afilias-nst.info. for ns1.ams1.afilias-nst.info./A.
Picked nameserver for: ns1.ams1.afilias-nst.info.
Switching authority: (ns1.ams1.afilias-nst.info.)
Switching zone: [org.->ietf.org.]
Querying server: 65.22.6.79 (39603)
Verifying zone change to [ietf.org.]
Checking signatures...
Querying server: 65.22.6.79 (6831)
Validated DNSSEC signatures.
Found alias to: www.ietf.org.cdn.cloudflare.net.
Alias changing zone: [ietf.org.->.]
Querying server: 192.36.148.17 (56154)
Verifying zone change to [.]
Checking signatures...
Cache hit for ./DNSKEY.
Validated DNSSEC signatures.
Switching authority: (m.gtld-servers.net.)
Switching zone: [.->net.]
Querying server: 192.35.51.30 (45165)
Verifying zone change to [net.]
Checking signatures...
Querying server: 192.48.79.30 (17999)
Validated DNSSEC signatures.
Switching authority: (ns2.cloudflare.net.)
Switching zone: [net.->cloudflare.net.]
Querying server: 2400:cb00:2049:1::adf5:3b1f (32228)
Verifying zone change to [cloudflare.net.]
Checking signatures...
Querying server: 2400:cb00:2049:1::adf5:3b1f (4323)
Validated DNSSEC signatures.
Traversed zones: ., org., ietf.org., ., net., cloudflare.net. for www.ietf.org./A.
Finishing resolving www.ietf.org./A (hops=10).

; <<>> dig.js 0.0.12 <<>> --recursive www.ietf.org +dnssec +debug
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32228
;; flags: qr ra ad; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 512
;; QUESTION SECTION:
;www.ietf.org. IN A

;; ANSWER SECTION:
www.ietf.org. 1800 IN CNAME www.ietf.org.cdn.cloudflare.net.
www.ietf.org. 1800 IN RRSIG CNAME 5 3 1800 20190214160829 20180214150920 40452 ietf.org. OAS6hbpld1KpNJBpqg/T+0m0FpcVV933AbsDuVlgloHQfyVG4Ug5iOtK QLKGNYw+583Ba1yhFlFsYu4GNALZFpF8Tw5NcmxpmXJyzpeO0aj1rSCH oFQzYaIszrbw7TmE2pYQbh9QeklO9hILxi/Q1D7VxzrtHj0Ff8ncgFI7 6Ep+ud0Gysr0m/5MrwO69LGPV06LTuMRP3cXv7hqbjmyn2CmYR3h6+lQ +uiHSwkZYK20xhk+w1pOP9CD6fIqGYCJiKVaMY8K2lMQyi6Ppx0zOmtk MdaJjnxrzQ5TXbCcGQ48Rn4hzdug1MvkJzh1DGWZH6ZnPQTEf3+O1ehz +zSpbQ==  ; alg = RSASHA1
www.ietf.org.cdn.cloudflare.net. 300 IN A 104.20.1.85
www.ietf.org.cdn.cloudflare.net. 300 IN A 104.20.0.85
www.ietf.org.cdn.cloudflare.net. 300 IN RRSIG A 13 6 300 20180406144148 20180404124148 35273 cloudflare.net. FUGqNUw+9Jb2Z/qJGByi2vBfzuS/X0tNbhtXMsboazqbYu5C/UlGch3u Uez482xYdVbm/+YeBy5Bu2vWKVtbsw==  ; alg = ECDSAP256SHA256

;; Query time: 1168 msec
;; WHEN: Thu Apr 05 06:41:30 PDT 2018
;; MSG SIZE  rcvd: 202

Contribution and License Agreement

If you contribute code to this project, you are implicitly allowing your code to be distributed under the MIT license. You are also implicitly verifying that all code is your original work. </legalese>

License

• Copyright (c) 2017-2018, Christopher Jeffrey (MIT License).

See LICENSE for more info.