ipfs.dns does not handle subdomains correctly

[niinpatel]

When I do ipfs.dns('docs.ipfs.io'). It throws an error 'ENODATA'. I did some digging and found out that this error is thrown by nodejs' dns.resolveTxt method when it does not find any txt records.

Now, to handle subdomain correctly, we need to append _dnslink. string to it, which we do here

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

Lines 20 to 22 in 3ef1ed4

	const _dnslinkDomain = `_dnslink.${domain}`
	// If this throws then we propagate the error
	return resolveDnslink(_dnslinkDomain)

But, the problem is, the error is way before the line gets to be executed, here:

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

Line 11 in 3ef1ed4

if (err.code !== 'ENOTFOUND' && err.code !== 'ERR_DNSLINK_NOT_FOUND') throw err

The easiest solution to this problem would be to check for err.code 'ENODATA' also along with 'ENOTFOUND', etc. in the if condition. So, the next lines get a chance to be executed.

Basically something like this:

      if (err.code !== 'ENOTFOUND' && err.code !== 'ERR_DNSLINK_NOT_FOUND' && err.code !== 'ENODATA') throw err

Would fix the problem.

What do you think?