When connecting ws://[::1]:8883, an error is thrown - Uncaught TypeError TypeError [ERR_INVALID_URL]: Invalid URL

[Steve-Mcl]

Hi, I am getting an exception when connecting to IPv6 localhost address ::1

I have found this was reported and fixed in #1130 / #1147 (commit 70a247c) however it seems to have been reverted and the current V4.3.7 is once more using the depreciated url.parse as you can see here: https://github.com/mqttjs/MQTT.js/blob/main/lib/connect/index.js#L64

Here is a minimal repro...

        const userEnteredURL = 'ws://[::1]:8883'
        const client = mqtt.connect(userEnteredURL, this.brokerConfig)

Here is why I think the underlying issue exists: mqtt.js manually rebuilds the broker URL using hostname + port in
https://github.com/mqttjs/MQTT.js/blob/main/lib/connect/ws.js#L20

let url = opts.protocol + '://' + opts.hostname + ':' + opts.port + opts.path

... but, url.parse().hostname drops the squarebrackets off [::1] which causes the above code to generate the url http://::1:8883. Further downstream, the ws package uses new URL(...) with this re-assembled URL string & the ERR_INVALID_URL error occurs.

For anyone else reading, here is a minimal (hacky) workaround...

        const userEnteredURL = 'ws://[::1]:8883'
        const tempNewURL= new URL(userEnteredURL)
        const brokerURL = url.parse(userEnteredURL)
        brokerURL.hostname = tempNewURL.hostname // force the hostname back to [::1]
        const client = mqtt.connect(brokerURL, this.brokerConfig)

---

Additional info...

• Calling mqtt.connect(new URL('http://[::1]:8883')) fails because connect only accepts a string or url.parse object
• Calling mqtt.connect(url.parse('http://[::1]:8883') fails because unlike new URL, url.parse drops the square brackets off hostname and mqtt.js uses hostnameto reassemble theurl`
• websocket code uses new URL so when mqtt.js passes the reassembled IP http://::1:8883 it failes with error ERR_INVALID_URL

url.parse vs new URL

url.parse('http://[::1]:8883')

Url {
  protocol: 'ws:',
  slashes: true,
  auth: null,
  host: '[::1]:8883',
  port: '8883',
  hostname: '::1', //<< square brackets are dropped
  hash: null,
  search: null,
  query: null,
  pathname: '/',
  path: '/',
  href: 'ws://[::1]:8883/'
}

new URL('http://[::1]:8883')

URL {
  href: 'ws://[::1]:8883/',
  origin: 'ws://[::1]:8883',
  protocol: 'ws:',
  username: '',
  password: '',
  host: '[::1]:8883',
  hostname: '[::1]', //<< square brackets are kept
  port: '8883',
  pathname: '/',
  search: '',
  searchParams: URLSearchParams {},
  hash: ''
}

[mklinke]

Might be relevant: nodejs/node#44731

[Steve-Mcl]

@mklinke no, I dont think so.

I strongly believe this is a bug in how this lib (MQTT.js) breaks down and re-assembles the URL as detailed in my initial post:

I have found this was reported and fixed in #1130 / #1147 (commit 70a247c) however it seems to have been reverted and the current V4.3.7 is once more using the depreciated url.parse as you can see here: https://github.com/mqttjs/MQTT.js/blob/main/lib/connect/index.js#L64

Here is a minimal repro...

        const userEnteredURL = 'ws://[::1]:8883'
        const client = mqtt.connect(userEnteredURL, this.brokerConfig)

Here is why I think the underlying issue exists: mqtt.js manually rebuilds the broker URL using hostname + port in https://github.com/mqttjs/MQTT.js/blob/main/lib/connect/ws.js#L20

[robertsLando]

Could you submit a PR to fix this?

[robertsLando]

MQTT 5.0.0 BETA is now available! Try it out and give us feedback: npm i mqtt@beta. It may fix your issues

[kmitchel]

While testing using a severs ipv6 address, I've noticed this issue. I construct a websocket url using window.location.hostname, when the error is thrown the URL is missing brackets. IPv6 connections using a name work properly, just not bracket notation. Using 5.5.0

[rockey2020]

same question.. when my url be mqtts://::1:14509 it cant be working , but i change to mqtts://127.0.0.1:14509 it work

[robertsLando]

Can anyone submit a PR to fix this issue? I think it's just a matter of url parsing here:

MQTT.js/src/lib/connect/index.ts

Line 71 in 9fc79df

const parsed = url.parse(brokerUrl, true)