Allow advertised IP addresses to be specified for each service

.gitignore

@@ -1 +1,2 @@
 node_modules
+.vscode

README.md

@@ -55,6 +55,9 @@ Options are:
 - `protocol` (string, optional) - `udp` or `tcp` (default)
 - `txt` (object, optional) - a key/value object to broadcast as the TXT
   record
+- `addresses` (array, optional) - array of IP addresses to advertise.
+  Array elements are IP address specifications as returned by
+  `os.networkInterfaces()`
 
 IANA maintains a [list of official service types and port
 numbers](http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml).

lib/browser.js

@@ -34,7 +34,6 @@ function Browser (mdns, opts, onup) {
 
   this._mdns = mdns
   this._onresponse = null
-  this._serviceMap = {}
   this._txt = dnsTxt(opts.txt)
 
   if (!opts || !opts.type) {
@@ -82,7 +81,15 @@ Browser.prototype.start = function () {
       if (matches.length === 0) return
 
       matches.forEach(function (service) {
-        if (self._serviceMap[service.fqdn]) return // ignore already registered services
+        var oldservice = self.services.find(function(s) { return s.fqdn === service.fqdn })
+        if (oldservice !== undefined && 
+          JSON.stringify(oldservice.addresses) === JSON.stringify(service.addresses) &&
+          oldservice.name === service.name &&
+          oldservice.host === service.host &&
+          oldservice.port === service.port &&
+          oldservice.type === service.type &&
+          oldservice.protocol === service.protocol) return // ignore already registered services
+        self._removeService(service.fqdn)
         self._addService(service)
       })
     })
@@ -105,7 +112,6 @@ Browser.prototype.update = function () {
 
 Browser.prototype._addService = function (service) {
   this.services.push(service)
-  this._serviceMap[service.fqdn] = true
   this.emit('up', service)
 }
 
@@ -120,7 +126,6 @@ Browser.prototype._removeService = function (fqdn) {
   })
   if (!service) return
   this.services.splice(index, 1)
-  delete this._serviceMap[fqdn]
   this.emit('down', service)
 }
 

lib/mdns-server.js

@@ -4,6 +4,8 @@ var multicastdns = require('multicast-dns')
 var dnsEqual = require('dns-equal')
 var flatten = require('array-flatten')
 var deepEqual = require('deep-equal')
+var ipRangeCheck = require('ip-range-check')
+var os = require('os')
 
 module.exports = Server
 
@@ -43,7 +45,7 @@ Server.prototype.unregister = function (records) {
   }
 }
 
-Server.prototype._respondToQuery = function (query) {
+Server.prototype._respondToQuery = function (query, rinfo) {
   var self = this
   query.questions.forEach(function (question) {
     var type = question.type
@@ -77,9 +79,20 @@ Server.prototype._respondToQuery = function (query) {
         })
         .filter(unique())
         .forEach(function (target) {
-          additionals = additionals
-            .concat(self._recordsFor(target, 'A'))
-            .concat(self._recordsFor(target, 'AAAA'))
+          additionals = additionals.concat(
+            Object.values(os.networkInterfaces())
+              .flat()
+              .filter(
+                (addressInfo) =>
+                  ipRangeCheck(rinfo.address, addressInfo.cidr)
+              )
+              .map((addressInfo) => ({
+                name: target,
+                type: addressInfo.family === 'IPv4' ? 'A' : 'AAAA',
+                ttl: 120,
+                data: addressInfo.address
+              }))
+          )
         })
     }
 

lib/service.js

@@ -26,6 +26,7 @@ function Service (opts) {
   this.subtypes = opts.subtypes || null
   this.txt = opts.txt || null
   this.published = false
+  this.addresses = opts.addresses || null
 
   this._activated = false // indicates intent - true: starting/started, false: stopping/stopped
 }
@@ -34,16 +35,14 @@ Service.prototype._records = function () {
   var records = [rrPtr(this), rrSrv(this), rrTxt(this)]
 
   var self = this
-  var interfaces = os.networkInterfaces()
-  Object.keys(interfaces).forEach(function (name) {
-    interfaces[name].forEach(function (addr) {
-      if (addr.internal) return
-      if (addr.family === 'IPv4') {
-        records.push(rrA(self, addr.address))
-      } else {
-        records.push(rrAaaa(self, addr.address))
-      }
-    })
+  var addresses = self.addresses || Object.values(os.networkInterfaces()).flat()
+  addresses.forEach(function (addr) {
+    if (addr.internal) return
+    if (addr.family === 'IPv4') {
+      records.push(rrA(self, addr.address))
+    } else {
+      records.push(rrAaaa(self, addr.address))
+    }
   })
 
   return records