digd.js

| dns-suite.js | dig.js | mdig.js | digd.js | Sponsored by Daplie.

A lightweight DNS / mDNS daemon (server) in node.js.

Although originally created for testing dns-suite.js by creating and capturing to disk DNS and mDNS query and response packets (as binary and/or JSON), digd.js has grown into a full-blown nameserver.

Options are similar to the Unix dig command.

Install

systemd service

curl -L https://git.coolaj86.com/coolaj86/digd.js/raw/v1.2/install.sh | bash

with git

# Install the latest of v1.x
npm install -g 'git+https://git.coolaj86.com/coolaj86/digd.js.git#v1'

# Install exactly v1.2.0
npm install -g 'git+https://git.coolaj86.com/coolaj86/digd.js.git#v1.2.0'

without git

Don't have git? Well, you can also bow down to the gods of the centralized, monopolized, concentrated, dictatornet (as we like to call it here at Daplie Labs), if that's how you roll:

npm install -g digd.js

Usage

digd.js --input <path/to/dns.json>

Example:

digd.js --input ./samples/db.json

Testing

# unix dig
dig @localhost example.com

# dns-suite's dig.js
dig.js @localhost example.com

# unix netcat
netcat -u 127.0.0.1 53 < ./samples/example.com.a.query.bin

Options

--output <path/to/file>     write query and response(s) to disk with this path prefix (ex: ./samples/dns)
--input <path/to/file>      input file to use for authoritative responses (ex: ./samples/db.json)

--mdns                      Use mDNS port (5353) and nameserver address (224.0.0.251)

-p <port>                   default 53 (mdns default: 5353) (listener is random for DNS and 5353 for mDNS)
--nameserver <ns>           alias of @<nameserver>
--timeout <ms>              alias of +time=<seconds>, but in milliseconds

@<nameserver>               specify the nameserver to use for recursive DNS resolutions (defaults to system defaults)
+time=<seconds>             Sets the timeout for a query in seconds.
+norecurse                  Set `ra` flag to 0. Do not perform recursion.
+aaonly                     Set `aa` flag to 1. Do not respond with non-authoritative responses.
+notcp                      Disable TCP server (default in v1.2)
+tcp                        Enable TCP server (default in v1.3)

--debug                     verbose output

JSON Database File

This DNS server is being created for use in the wild. Although there will be a true database adapter later, this JSON representation gives us an easy way to experiment with serving DNS and various record types.

There are 4 types of information in the file:

• Primary Nameservers primaryNameservers
• SOA Records domains
• devices
• All other records (A, AAAA, CAA, CNAME, MX, NS, PTR, SPF, SRV, TXT)

module.exports = {
  primaryNameservers: [ 'ns1.example.com', 'ns2.example.com' ]

  // SOA records
, domains: [
    // `primary` is chosen at random from `primaryNameservers` or `vanityNs`
    // `serial` is generated from `updatedAt`

    { id: "publicsuffix.net", updatedAt: 1507594095118, ttl: 60
    , admin: 'admin.publicsuffix.net', refresh: 1800, retry: 600
    , expiration: 2419200, minimum: 5 }

  , { id: "doe.publicsuffix.net", updatedAt: 1507594095118, ttl: 60
    , admin: 'admin.doe.publicsuffix.net', refresh: 1800, retry: 600
    , expiration: 2419200, minimum: 5 }


    // default values will be used when left undefined
  , { id: "doefam.net", updatedAt: 1507594095118
    , vanityNs: [ 'ns1.awesome.com', 'ns2.awesome.com' ] }
  ]
, records: [
    //
    // Plain old boring A Records
    //
    { name: "publicsuffix.net", zone: "publicsuffix.net"
    , tld: "net", sld: "publicsuffix", sub: ""
    , type: 'A', ttl: 300, address: '127.0.0.1' }

    { name: "www.publicsuffix.net", zone: "publicsuffix.net"
    , tld: "net", sld: "publicsuffix", sub: "www"
    , type: 'A', ttl: 300, address: '127.0.0.1' }

    //
    // Subdomain Delegation of a public suffix (treated as TLD)
    //
    { name: "jane.doe.publicsuffix.net", zone: "doe.publicsuffix.net"
    , tld: "publicsuffix.net", sld: "doe", sub: "john"
    , type: 'NS', ttl: 300, data: 'ns1.other-dns.net'
    }

    //
    // Example of all other record types
    //
    { name: "john.doe.publicsuffix.net"

      // The zone / SOA it belongs to (keep in mind that subdomains can be delegated to other users and/or nameservers)
    , zone: "doe.publicsuffix.net"

      // For indexing (note that we can treat delegated subdomains as if they were TLDs for delegation and resale)
    , tld: "publicsuffix.net"
    , sld: "doe"
    , sub: "john"

    , type: 'A'           // for this example we specify a type even though we show all of the record data
    , class: 'IN'         // (default)
    , ttl: 300

      // A, AAAA
    , address: '127.0.0.1'
    , aname: 'some-device.example.com' // See "A Note on ANAMEs" below

      // CAA
    , flag: 0
    , tag: 'issue'
    , value: 'letsencrypt.org'

      // CNAME, NS, PTR put 'name' here
      // TXT puts an array here
    , data: 'a.example.com'

      // MX, SRV
    , priority: 10

      // MX
    , exchange: 'mxa.example.org'

      // SRV
    , weight: 20
    , port: 65065
    , target: 'laptop1.devices.example.com'
    }
  ]
};

The Primary Nameservers should be all of the nameservers that are in sync for these collections of records.

The SOA records represent that a domain or subdomain has be registered to or delegated to these nameservers. The SOA records are separate from other record types because they are automatically generated as part of registering a domain or updating its records.

The other records are in their own table for easy and fast lookup.

The devices are an abstraction that will be used in the future for ANAMEs and Dynamic DNS.

Note: Because it's possible to that delegated subdomains could have delegated subdomains that go right back to the original nameserver, NS records will be replaced with an SOA record if any of the NS records match any of the server's primary nameservers or if vanity nameservers are used.

A Note on ANAMES

ANAMEs serve two purposes in this system:

1. Traditional ANAME. Just a CNAME that is automatically resolved to an A record for the "bare domain" problem, and efficiency.
2. Dynamic DNS. When a record on the system is updated, any records that match it by ANAME are also updated

TODO: use dns0x20 for ANAME resolutions

Other Resources

You may also be interested in Unbound (https://unboundtest.com), which is an entirely different project by someone else which is much more complete, written in go, and may be very useful for debugging and linting.

LICENSE

You may, at your option, use this software under the MIT and/or Apache-2.0 licenses.