fix: support dns and dnsaddr (#253)

Not sure why but we currently can't parse `/dns/foo.com/...` or
`/dnsaddr/foo.com/...` so this PR fixes that.

src/index.ts

@@ -9,6 +9,17 @@ import { equals as uint8ArrayEquals } from 'uint8arrays/equals'
 
 const inspect = Symbol.for('nodejs.util.inspect.custom')
 
+const IP_CODES = [
+  getProtocol('ip4').code,
+  getProtocol('ip6').code
+]
+const DNS_CODES = [
+  getProtocol('dns').code,
+  getProtocol('dns4').code,
+  getProtocol('dns6').code,
+  getProtocol('dnsaddr').code
+]
+
 export interface Protocol {
   code: number
   size: number
@@ -447,8 +458,8 @@ export class Multiaddr {
 
     if (parts.length < 4) {
       throw new Error('multiaddr must have a valid format: "/{ip4, ip6, dns4, dns6}/{address}/{tcp, udp}/{port}".')
-    } else if (codes[0] !== 4 && codes[0] !== 41 && codes[0] !== 54 && codes[0] !== 55) {
-      throw new Error(`no protocol with name: "'${names[0]}'". Must have a valid family name: "{ip4, ip6, dns4, dns6}".`)
+    } else if (!IP_CODES.includes(codes[0]) && !DNS_CODES.includes(codes[0])) {
+      throw new Error(`no protocol with name: "'${names[0]}'". Must have a valid family name: "{ip4, ip6, dns, dns4, dns6, dnsaddr}".`)
     } else if (parts[2] !== 'tcp' && parts[2] !== 'udp') {
       throw new Error(`no protocol with name: "'${names[1]}'". Must have a valid transport protocol: "{tcp, udp}".`)
     }

test/index.spec.ts

@@ -686,6 +686,16 @@ describe('helpers', () => {
     })
 
     it('returns a node friendly address with dns', () => {
+      expect(
+        new Multiaddr('/dns/wss0.bootstrap.libp2p.io/tcp/443').nodeAddress()
+      ).to.be.eql({
+        address: 'wss0.bootstrap.libp2p.io',
+        family: 4,
+        port: 443
+      })
+    })
+
+    it('returns a node friendly address with dns4', () => {
       expect(
         new Multiaddr('/dns4/wss0.bootstrap.libp2p.io/tcp/443').nodeAddress()
       ).to.be.eql({
@@ -695,6 +705,26 @@ describe('helpers', () => {
       })
     })
 
+    it('returns a node friendly address with dns6', () => {
+      expect(
+        new Multiaddr('/dns6/wss0.bootstrap.libp2p.io/tcp/443').nodeAddress()
+      ).to.be.eql({
+        address: 'wss0.bootstrap.libp2p.io',
+        family: 6,
+        port: 443
+      })
+    })
+
+    it('returns a node friendly address with dnsaddr', () => {
+      expect(
+        new Multiaddr('/dnsaddr/wss0.bootstrap.libp2p.io/tcp/443').nodeAddress()
+      ).to.be.eql({
+        address: 'wss0.bootstrap.libp2p.io',
+        family: 4,
+        port: 443
+      })
+    })
+
     it('throws on an invalid format address when the addr is not prefixed with a /', () => {
       expect(
         () => new Multiaddr('ip4/192.168.0.1/udp').nodeAddress()