DNS support (#56)

* feat: dns support

src/ma-to-url.js

@@ -0,0 +1,22 @@
+'use strict'
+
+const multiaddr = require('multiaddr')
+
+function maToUrl (ma) {
+  const maStrSplit = ma.toString().split('/')
+  const proto = ma.protos()[2].name
+
+  if (!(proto === 'ws' || proto === 'wss')) {
+    throw new Error('invalid multiaddr' + ma.toString())
+  }
+
+  let url = ma.protos()[2].name + '://' + maStrSplit[2]
+
+  if (!multiaddr.isName(ma)) {
+    url += ':' + maStrSplit[4]
+  }
+
+  return url
+}
+
+module.exports = maToUrl