feat: recursive dnslink lookups

[niinpatel]

fixes #1931 .

Also, incorporated the suggestions from https://github.com/ipfs/interface-js-ipfs-core/issues/377 that ipfs dns should be recursive by default.

[niinpatel]

Here's the quick demo of this feature working on the cli. I've included tests to make sure it works all other places like http-api, browsers, etc.

[niinpatel]

@alanshaw can you review this one when you can?

[alanshaw]

Thanks @niinpatel - I will look at this as soon as I get a moment!

[niinpatel]

@alanshaw did you get a chance to check it out?

[alanshaw]

Awesome work @niinpatel 🚀

[alanshaw]

Default true for null/undefined and boolean value of argument otherwise:

Suggested change

	const recursive = opts.recursive === undefined || opts.recursive.toString() === 'true'
	const recursive = opts.recursive == null ? true : Boolean(opts.recursive)

[niinpatel]

Boolean("false") actually returns true not false. Arguments passed via query parameters are of string type and we need to parse those too. Once easy solution I just now came up with is this:

const recursive = opts.recursive.toString() !== 'false'

If recursive is false or "false" then only we parse it as false. true when passed anything else, including null and undefined

[niinpatel]

Edit: That wouldn't work either because error will be thrown if opts.recursive is undefined.

The original one is probably the best solution after all, with slight modifications:

js-ipfs/src/core/runtime/dns-nodejs.js

Line 12 in d6b2ca3

const recursive = opts.recursive == null || opts.recursive.toString() !== 'false'

[alanshaw]

Arguments passed via query parameters are of string type and we need to parse those too

It should be passed as a boolean - this is the documented type for the value. If a string is being passed then we need to fix our HTTP endpoint to properly parse query strings to the expected types for the calls to core.

We can't guarantee the passed value is a boolean but we can ensure that the value is a boolean for the rest of our code.

[niinpatel]

That makes sense. Right now, I don't think query parameters are being parsed and "type-casted" before passing to the core API. For this PR, I've just now add it here:

js-ipfs/src/http/api/resources/dns.js

Lines 14 to 18 in fb114f1

	// query parameters are passed as strings and need to be parsed to expected type
	let recursive = request.query.recursive || request.query.r
	recursive = !(recursive && recursive === 'false')
	const path = await request.server.app.ipfs.dns(domain, { recursive, format })

[niinpatel]

I've applied all the suggested changes.

[alanshaw]

LGTM, thank you @niinpatel ❤️