feat: resolution of .eth names via .eth.link

.eth TLD is not recognised by mainstream DNS,
however ENS provides DNS compatibility service at .eth.link

This change enables resolution of ENS names ending with .eth
on systems that  have regular DNS set up

More context at the go-ipfs counterpart:
ipfs/kubo#6448

License: MIT
Signed-off-by: Marcin Rataj <lidel@lidel.org>

src/core/components/dns.js

@@ -4,6 +4,15 @@
 const dns = require('../runtime/dns-nodejs')
 const promisify = require('promisify-es6')
 
+function fqdnFixups (domain) {
+  // Allow resolution of .eth names via .eth.link
+  // More context at the go-ipfs counterpart: https://github.com/ipfs/go-ipfs/pull/6448
+  if (domain.endsWith('.eth')) {
+    domain = domain.replace(/.eth$/, '.eth.link')
+  }
+  return domain
+}
+
 module.exports = () => {
   return promisify((domain, opts, callback) => {
     if (typeof domain !== 'string') {
@@ -16,6 +25,7 @@ module.exports = () => {
     }
 
     opts = opts || {}
+    domain = fqdnFixups(domain)
 
     dns(domain, opts, callback)
   })

test/http-api/inject/dns.js

@@ -11,13 +11,22 @@ module.exports = (http) => {
       api = http.api._httpApi._apiServers[0]
     })
 
-    it('resolve ipfs.io dns', async () => {
+    it('resolve ipfs.io DNS', async () => {
       const res = await api.inject({
         method: 'GET',
         url: '/api/v0/dns?arg=ipfs.io'
       })
 
       expect(res.result).to.have.property('Path')
     })
+
+    it('resolve ipfs.enstest.eth ENS', async () => {
+      const res = await api.inject({
+        method: 'GET',
+        url: '/api/v0/dns?arg=ipfs.enstest.eth'
+      })
+
+      expect(res.result).to.have.property('Path')
+    })
   })
 }