@dnslink/js

@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:

import { resolve, DNSRcodeError } from '@dnslink/js'

// assumes top-level await
let result
try {
  result = await resolve('dnslink.dev/abcd?foo=bar', {
    endpoints: ['dns.google'], // required! see more below.
    /* (optional) */
    signal, // AbortSignal that you can use to abort the request
    timeout: 1000, // timeout for the operation
    retries: 3 // retries in case of transport error
  })
} catch (err) {
  // Errors provided by DNS server
  if (err instanceof DNSRcodeError) {
    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 }]

Endpoints

You need to specify endpoints to be used with the API. You can specify them the same way as you would in dns-query.

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.

.code	Meaning	Additional properties
FALLBACK	No _dnslink. prefixed domain was found. Falling back to the regular domain.
INVALID_ENTRY	A TXT entry with dnslink= prefix has formatting errors.	.entry, .reason

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:

$ npx @dnslink/js --help

License

Published under dual-license: MIT OR Apache-2.0