feat: enable recursive lookups on ipfs.dns

Author: niinpatel

README.md

@@ -639,6 +639,7 @@ The core API is grouped into several areas:
   - [`ipfs.stop([callback])`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/MISCELLANEOUS.md#stop)
   - `ipfs.isOnline()`
   - [`ipfs.resolve(name, [options], [callback])`](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/MISCELLANEOUS.md#resolve)
+  - [`ipfs.dns(name, [options], [callback]`](https://github.com/ipfs/interface-js-ipfs-core/blob/master/SPEC/MISCELLANEOUS.md#dns)
 
 - [repo](https://github.com/ipfs/interface-ipfs-core/tree/master/SPEC/REPO.md)
   - `ipfs.repo.init`

src/cli/commands/dns.js

@@ -7,15 +7,21 @@ module.exports = {
   describe: 'Resolve DNS links',
 
   builder: {
+    recursive: {
+      type: 'boolean',
+      default: false,
+      alias: 'r',
+      desc: 'Resolve until the result is not a DNS link'
+    },
     format: {
       type: 'string'
     }
   },
 
-  handler ({ getIpfs, domain, resolve }) {
+  handler ({ getIpfs, domain, resolve, ...opts }) {
     resolve((async () => {
       const ipfs = await getIpfs()
-      const path = await ipfs.dns(domain)
+      const path = await ipfs.dns(domain, opts)
       print(path)
     })())
   }

src/core/runtime/dns-nodejs.js

@@ -2,10 +2,27 @@
 
 const dns = require('dns')
 const _ = require('lodash')
+const isIPFS = require('is-ipfs')
 const errcode = require('err-code')
 
+const maxRecursiveDepth = 32
+
 module.exports = (domain, opts, callback) => {
-  resolveDnslink(domain)
+  const recursive = opts.recursive && opts.recursive.toString() === 'true'
+  let depth
+  if (recursive) {
+    depth = maxRecursiveDepth
+  }
+
+  return recursiveResolveDnslink(domain, depth, callback)
+}
+
+function recursiveResolveDnslink (domain, depth, callback) {
+  if (depth === 0) {
+    return callback(errcode(`recursion limit exceeded`, 'ERR_DNSLINK_RECURSION_LIMIT'))
+  }
+
+  return resolveDnslink(domain)
     .catch(err => {
       // If the code is not ENOTFOUND or ERR_DNSLINK_NOT_FOUND or ENODATA then throw the error
       if (err.code !== 'ENOTFOUND' && err.code !== 'ERR_DNSLINK_NOT_FOUND' && err.code !== 'ENODATA') throw err
@@ -22,7 +39,14 @@ module.exports = (domain, opts, callback) => {
       return resolveDnslink(_dnslinkDomain)
     })
     .then(dnslinkRecord => {
-      callback(null, dnslinkRecord.replace('dnslink=', ''))
+      const result = dnslinkRecord.replace('dnslink=', '')
+      const domainOrCID = result.split('/')[2]
+      const isIPFSCID = isIPFS.cid(domainOrCID)
+
+      if (isIPFSCID || !depth) {
+        return callback(null, result)
+      }
+      return recursiveResolveDnslink(domainOrCID, depth - 1, callback)
     })
     .catch(callback)
 }

src/http/api/resources/dns.js

@@ -3,11 +3,13 @@
 const Boom = require('boom')
 
 module.exports = async (request, h) => {
-  if (!request.query.arg) {
+  const { arg: domain, ...opts } = request.query
+
+  if (!domain) {
     throw Boom.badRequest("Argument 'domain' is required")
   }
 
-  const path = await request.server.app.ipfs.dns(request.query.arg)
+  const path = await request.server.app.ipfs.dns(domain, opts)
   return h.response({
     Path: path
   })

test/core/dns.spec.js

@@ -0,0 +1,62 @@
+/* eslint-env mocha */
+'use strict'
+
+const chai = require('chai')
+const dirtyChai = require('dirty-chai')
+const expect = chai.expect
+chai.use(dirtyChai)
+
+const IPFSFactory = require('ipfsd-ctl')
+const IPFS = require('../../src/core')
+
+describe('.dns', () => {
+  let ipfsd, ipfs
+
+  before(function (done) {
+    this.timeout(20 * 1000)
+
+    const factory = IPFSFactory.create({ type: 'proc' })
+
+    factory.spawn({
+      exec: IPFS,
+      initOptions: { bits: 512 },
+      config: { Bootstrap: [] }
+    }, (err, _ipfsd) => {
+      expect(err).to.not.exist()
+      ipfsd = _ipfsd
+      ipfs = _ipfsd.api
+      done()
+    })
+  })
+
+  after((done) => {
+    if (ipfsd) {
+      ipfsd.stop(done)
+    } else {
+      done()
+    }
+  })
+
+  // skipping because there is an error in https://ipfs.io/api/v0/dns?arg=ipfs.io
+  // unskip once this is resolved: https://github.com/ipfs/go-ipfs/issues/6086
+  it.skip('should resolve ipfs.io', () => {
+    return ipfs.dns('ipfs.io').then(res => {
+      // matches pattern /ipns/<ipnsaddress>
+      expect(res).to.match(/\/ipns\/.+$/)
+    })
+  })
+
+  it('should recursively resolve ipfs.io', () => {
+    return ipfs.dns('ipfs.io', { recursive: true }).then(res => {
+      // matches pattern /ipfs/<hash>
+      expect(res).to.match(/\/ipfs\/.+$/)
+    })
+  })
+
+  it('should resolve subdomain docs.ipfs.io', () => {
+    return ipfs.dns('docs.ipfs.io').then(res => {
+      // matches pattern /ipfs/<hash>
+      expect(res).to.match(/\/ipfs\/.+$/)
+    })
+  })
+})