@dnslink/js

The reference implementation for DNSLink resolver in JavaScript. Tested in Node.js and in the Browser.

Usage

You can use dnslink both as a CLI tool or a library.

JavaScript API

Getting started with DNSLink resolution in a jiffy:

const { resolve, createLookupTXT, RCodeError } = require('@dnslink/js')

// assumes top-level await
let result
try {
  result = await resolve('dnslink.dev/abcd?foo=bar')
} catch (err) {
  // Errors provided by DNS server
  if (err instanceof RCodeError) {
    err.rcode // Error code number following - https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6
    err.error // Error code name following (same list)
    err.code // `RCODE_${err.code}
    err.domain // Domain lookup that resulted in the error
    if (err.rcode === 3) {
      // NXDomain = Domain not found; most relevant error
    }
  } else {
    // A variety other errors may be thrown as well. Possible causes include, but are not limited to:
    // - Invalid input
    // - Timeouts / aborts
    // - Networking errors
    // - Incompatible dns packets provided by server
  }
}
const { links, log, txtEntries } = result

// `links` is an object containing given links for the different namespaces
// Each names contains an identifier and a ttl.
links.ipfs === [{ identifier: 'QmTg....yomU', ttl: 60 }]

// The `log` is always an Array and contains a list of log entries
// that were should help to trace back how the linked data was resolved.
Array.isArray(log)

// The `txtEntries` are a reduced form of the links that contains the namespace 
// as part of the value
txtEntries === [{ value: '/ipfs/QmTg....yomU', ttl: 60 }]

You can also pass a set of options:

let endpoints // custom endpoints
endpoints = 'dns' // Use the system default dns servers to resolve (Node.js only!)
endpoints = [`udp://1.1.1.1`] // DNS server endpoint
endpoints = 'doh' // Use any of the given default https://github.com/martinheidegger/doh-query/blob/main/endpoints.md
endpoints = ['google'] // Use the "google" endpoint of above list ↑
endpoints = ['https://cloudflare-dns.com/dns-query'] // Use a custom DoH endpoin
// More about ↑ here: https://github.com/martinheidegger/dns-query#string-endpoints

await resolve('dnslink.dev', {
  signal, // AbortSignal that you can use to abort the request
  timeout: 1000, // (optional) timeout for the operation
  lookupTXT: /* (optional) */ createLookupTXT(
    retries: 3, // (optional, default=5)
    endpoints // (optional, defaults )
  )
})

Possible log statements

The statements contained in the log are all objects. They may be helpful to figure out why dnslink is not behaving like you expect. Every statement contains the .code property that holds the .code property to understand what happened. Depending on the warnings code the errors may have additional .entry property that holds the problematic TXT entry. A .reason property may contain an additional reason for that error to occur.

Command Line

To use dnslink in the command line you will need Node.js installed.

Install it permanently using npm i -g @dnslink/js or run in on-the-fly using npx @dnslink/js.

You can get detailed help for the app by passing a --help option at the end:

dnslink - resolve dns links in TXT records

USAGE
    dnslink [--help] [--format=json|text|csv] [--dns] [--doh] [--debug] \
        [--ns=<ns>] [--first=<ns>] [--endpoint[=<endpoint>]] \
        <hostname> [...<hostname>]

EXAMPLE
    # Receive the dnslink entries for the dnslink.io domain.
    > dnslink t15.dnslink.dev
    /ipns/AANO      [ttl=3600]

    # Receive only the ipfs entry as text for dnslink.io
    > dnslink -k=ipfs dnslink.io
    bafkreidj5lipga46mwq4wdkrrmarjmppobvtsqssge6o5nhkyvsp6pom3u [ttl=60]

    # Receive only the ipfs entry as text for dnslink.io using DNS
    > dnslink -k=ipfs --dns dnslink.io
    bafkreidj5lipga46mwq4wdkrrmarjmppobvtsqssge6o5nhkyvsp6pom3u [ttl=60]

    # Receive only the first ipfs entry as text for dnslink.io using DNS
    > dnslink --first=ipfs --dns dnslink.io
    bafkreidj5lipga46mwq4wdkrrmarjmppobvtsqssge6o5nhkyvsp6pom3u [ttl=60]

    # Receive all dnslink entries for multiple domains as csv
    > dnslink -f=csv dnslink.io ipfs.io
    lookup,namespace,identifier,ttl
    "dnslink.io","ipfs","QmTgQDr3xNgKBVDVJtyGhopHoxW4EVgpkfbwE4qckxGdyo",60
    "ipfs.io","ipns","website.ipfs.io",60

    # Receive ipfs entries for multiple domains as json
    > dnslink -f=json -k=ipfs dnslink.io website.ipfs.io
    [
    {"lookup":"website.ipfs.io","links":{"ipfs":[{"identifier":"bafybeiagozluzfopjadeigrjlsmktseozde2xc5prvighob7452imnk76a","ttl":32}]}}
    ,{"lookup":"dnslink.io","links":{"ipfs":[{"identifier":"QmTgQDr3xNgKBVDVJtyGhopHoxW4EVgpkfbwE4qckxGdyo","ttl":120}]}}
    ]

    # Receive both the result and log and write the output to files
    > dnslink -f=csv -d dnslink.io \
        >dnslink-io.csv \
        2>dnslink-io.log.csv

OPTIONS
    --help, -h            Show this help.
    --version, -v         Show the version of this command.
    --format, -f          Output format json, text, reduced or csv (default=text)
    --dns                 Use one of default dns endpoints.
    --doh                 Use one of default doh endpoints.
    --endpoint=<server>   Specify a dns or doh server to use. If more than
                          one endpoint is specified it will use one of the
                          specified at random. More about specifying
                          servers in the dns-query docs: [1]
    --debug, -d           Render log output to stderr in the specified format.
    --ns, -n              Only render one particular DNSLink namespace.
    --first               Only render the first of the defined DNSLink namespace.

    [1]: https://github.com/martinheidegger/dns-query#string-endpoints

NOTE
    If you specify --dns, --doh and --endpoint will be ignored. If you specify
    --doh then --endpoint will be ignored.

License

Published under dual-license: MIT OR Apache-2.0