DNS over HTTPS support

[szmarczak]

[lokesh411]

One question, would we be using cloudflare or google DoH APIs for this (Ex.: https://cloudflare-dns.com/dns-query). Interested to contribute here

[szmarczak]

I think the CloudFlare one is a good start to implement, then we can do something like this:

const cacheable = new CacheableLookup();

cacheable.servers = [
	  '8.8.8.8', // DNS over UDP/TCP
	  'https://1.1.1.1/dns-query', // DNS over HTTPS
];

There's a spec at https://datatracker.ietf.org/doc/html/rfc8484

---

I'd do this by storing HTTP/2 sessions in an object (key would be a string starting with https://). We can detect cacheable.servers changes in

https://github.com/szmarczak/cacheable-lookup/blob/45b18daf9f0c8406691fad81188e956641e2309d/source/index.js#L134-L138

so when it's updated, we close sessions that are no longer required and open new ones if there shall be. Then when a user makes a DNS request

https://github.com/szmarczak/cacheable-lookup/blob/45b18daf9f0c8406691fad81188e956641e2309d/source/index.js#L240

we simply go through the list and send a HTTP/2 request to the DoH server and handle that. Note that dns.Resolver doesn't accept DoH servers so we need to filter the list before calling resolver.setServers.

---

It's possible that there may be multiple DoH servers. This can be quite a hassle, so no need to do this all in one PR.

[lokesh411]

Thanks, would go through the specification once, DoH queries should be round robin if multiple DoH servers are given right?

[szmarczak]

No, those should be fallback servers. As per Node.js docs:

Fallback DNS servers will only be used if the earlier ones time out or result in some other error.

[lokesh411]

Got it, thanks

[Kikobeats]

I created doh-resolver to use DNS-over-HTTPS as resolver with cacheable-lookup:

const CacheableLookup = require('cacheable-lookup')
const DoHResolver = require('doh-resolver')
const https = require('https')

const resolver = new DoHResolver({ servers: ['1.1.1.1', '8.8.8.8'] })

const cacheable = new CacheableLookup({ resolver })

https.get('https://example.com', { lookup: cacheable.lookup }, response => {
  // Handle the response here
})

[szmarczak]

Awesome! It's quite heavy though, can you reduce the size?

[Kikobeats]

yea, I'm working on it; the main dependency is dns2 that is exporting a lot of things I really don't need

[szmarczak]

Are you sure?

[Kikobeats]

gotcha; shipped [email protected] that removes the logger dependency

[szmarczak]

Awesome! Would you be up to sending a PR mentioning this in the docs?

[titanism]

PR #77 fixes this! 🎉

See 🍊 Tangerine and https://github.com/forwardemail/tangerine/issues/1.

[titanism]

Reported as spam to GitHub

[titanism]

Reported for spam

[Kikobeats]

BTW this is how I use cacheable-lookup with tangerine for getting DNS-over-HTTPs:

new CacheableLookup({
  resolver: new Tangerine(
    {
      cache: false,
    },
    require('got').extend({
      responseType: 'buffer',
      decompress: false,
      retry: 0
    })
  )
})

If this looks good to @titanism I can create a PR to add it into the README 🙂

[titanism]

You're welcome to add whatever you like! This nicely shows how it supports things other than undici.