Support services query

lib/mdns-server.js

@@ -7,6 +7,8 @@ var deepEqual = require('deep-equal')
 
 module.exports = Server
 
+const WILDCARD = '_services._dns-sd._udp.local'
+
 function Server (opts) {
   this.mdns = multicastdns(opts)
   this.mdns.setMaxListeners(0)
@@ -50,9 +52,15 @@ Server.prototype._respondToQuery = function (query) {
     var name = question.name
 
     // generate the answers section
-    var answers = type === 'ANY'
-      ? flatten.depth(Object.keys(self.registry).map(self._recordsFor.bind(self, name)), 1)
-      : self._recordsFor(name, type)
+    var answers = []
+    if (type === 'PTR' && name === WILDCARD) {
+      // Handle Service Type Enumeration (http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt section 9)
+      answers = self._wildcard()
+    } else {
+      answers = type === 'ANY'
+        ? flatten.depth(Object.keys(self.registry).map(self._recordsFor.bind(self, name)), 1)
+        : self._recordsFor(name, type)
+    }
 
     if (answers.length === 0) return
 
@@ -98,6 +106,21 @@ Server.prototype._recordsFor = function (name, type) {
   })
 }
 
+Server.prototype._wildcard = function () {
+  if (!('PTR' in this.registry)) return []
+
+  return this.registry['PTR'].map(function (entry) {
+    return {
+      name: WILDCARD,
+      type: 'PTR',
+      class: 1,      // TODO: Should these be dynamic?
+      ttl: 4500,     // TODO: Should these be dynamic?
+      flush: false,  // TODO: Should these be dynamic?
+      data: entry.name
+    }
+  })
+}
+
 function isDuplicateRecord (a) {
   return function (b) {
     return a.type === b.type &&