made the mDNS module able to adapt to changes in config

lib/goldilocks.js

@@ -301,13 +301,12 @@ module.exports.create = function (deps, config) {
       mainPort = Object.keys(unforwarded).map(Number).sort((a, b) => a - b)[0];
     }
   }
-
   updateConf();
-  if (!config.mdns.disabled) {
-    require('./mdns').start(deps, config, mainPort);
-  }
 
-  return {
+  var result =  {
     updateConf
   };
+  Object.defineProperty(result, 'mainPort', {enumerable: true, get: () => mainPort});
+
+  return result;
 };

lib/mdns.js

@@ -2,6 +2,7 @@
 
 var PromiseA = require('bluebird');
 var queryName = '_cloud._tcp.local';
+var dnsSuite = require('dns-suite');
 
 function createResponse(name, ownerIds, packet, ttl, mainPort) {
   var rpacket = {
@@ -85,20 +86,19 @@ function createResponse(name, ownerIds, packet, ttl, mainPort) {
     });
   });
 
-  return require('dns-suite').DNSPacket.write(rpacket);
+  return dnsSuite.DNSPacket.write(rpacket);
 }
 
-module.exports.start = function (deps, config, mainPort) {
-  var socket = require('dgram').createSocket({ type: 'udp4', reuseAddr: true });
-  var dns = require('dns-suite');
+module.exports.create = function (deps, config) {
+  var socket;
   var nextBroadcast = -1;
 
-  socket.on('message', function (message, rinfo) {
+  function handlePacket(message, rinfo) {
     // console.log('Received %d bytes from %s:%d', message.length, rinfo.address, rinfo.port);
 
     var packet;
     try {
-      packet = dns.DNSPacket.parse(message);
+      packet = dnsSuite.DNSPacket.parse(message);
     }
     catch (er) {
       // `dns-suite` actually errors on a lot of the packets floating around in our network,
@@ -108,16 +108,12 @@ module.exports.start = function (deps, config, mainPort) {
     }
 
     // Only respond to queries.
-    if (packet.header.qr !== 0) {
-      return;
-    }
+    if (packet.header.qr !== 0) {  return; }
     // Only respond if they were asking for cloud devices.
-    if (packet.question.length !== 1 || packet.question[0].name !== queryName) {
-      return;
-    }
-    if (packet.question[0].typeName !== 'PTR' || packet.question[0].className !== 'IN' ) {
-      return;
-    }
+    if (packet.question.length !== 1)           { return; }
+    if (packet.question[0].name !== queryName)  { return; }
+    if (packet.question[0].typeName !== 'PTR')  { return; }
+    if (packet.question[0].className !== 'IN' ) { return; }
 
     var proms = [
       deps.storage.mdnsId.get()
@@ -131,7 +127,7 @@ module.exports.start = function (deps, config, mainPort) {
     ];
 
     PromiseA.all(proms).then(function (results) {
-      var resp = createResponse(results[0], results[1], packet, config.mdns.ttl, mainPort);
+      var resp = createResponse(results[0], results[1], packet, config.mdns.ttl, deps.tcp.mainPort);
       var now = Date.now();
       if (now > nextBroadcast) {
         socket.send(resp, config.mdns.port, config.mdns.broadcast);
@@ -140,18 +136,67 @@ module.exports.start = function (deps, config, mainPort) {
         socket.send(resp, rinfo.port, rinfo.address);
       }
     });
-  });
+  }
 
-  socket.bind(config.mdns.port, function () {
-    var addr = this.address();
-    console.log('bound on UDP %s:%d for mDNS', addr.address, addr.port);
+  function start() {
+    socket = require('dgram').createSocket({ type: 'udp4', reuseAddr: true });
+    socket.on('message', handlePacket);
 
-    socket.setBroadcast(true);
-    socket.addMembership(config.mdns.broadcast);
-    // This is supposed to be a local device discovery mechanism, so we shouldn't
-    // need to hop through any gateways. This helps with security by making it
-    // much more difficult for someone to use us as part of a DDoS attack by
-    // spoofing the UDP address a request came from.
-    socket.setTTL(1);
-  });
+    return new Promise(function (resolve, reject) {
+      socket.once('error', reject);
+
+      socket.bind(config.mdns.port, function () {
+        var addr = this.address();
+        console.log('bound on UDP %s:%d for mDNS', addr.address, addr.port);
+
+        socket.setBroadcast(true);
+        socket.addMembership(config.mdns.broadcast);
+        // This is supposed to be a local device discovery mechanism, so we shouldn't
+        // need to hop through any gateways. This helps with security by making it
+        // much more difficult for someone to use us as part of a DDoS attack by
+        // spoofing the UDP address a request came from.
+        socket.setTTL(1);
+
+        socket.removeListener('error', reject);
+        resolve();
+      });
+    });
+  }
+  function stop() {
+    return new Promise(function (resolve, reject) {
+      socket.once('error', reject);
+
+      socket.close(function () {
+        socket.removeListener('error', reject);
+        socket = null;
+        resolve();
+      });
+    });
+  }
+
+  function updateConf() {
+    var promise;
+    if (config.mdns.disabled) {
+      if (socket) {
+        promise = stop();
+      }
+    } else {
+      if (!socket) {
+        promise = start();
+      } else if (socket.address().port !== config.mdns.port) {
+        promise = stop().then(start);
+      } else {
+        // Can't check membership, so just add the current broadcast address to make sure
+        // it's set. Hopefully nothing bad happens by adding multiple addresses or adding
+        // the same address multiple times.
+        socket.addMembership(config.mdns.broadcast);
+        promise = Promise.resolve();
+      }
+    }
+  }
+  updateConf();
+
+  return {
+    updateConf
+  };
 };

lib/worker.js

@@ -51,6 +51,7 @@ function create(conf) {
   , proxy:    require('./proxy-conn').create(deps, conf)
   , socks5:   require('./socks5-server').create(deps, conf)
   , ddns:     require('./ddns').create(deps, conf)
+  , mdns:     require('./mdns').create(deps, conf)
   , udp:      require('./udp').create(deps, conf)
   , tcp:      require('./goldilocks').create(deps, conf)
   };

package-lock.json

@@ -448,7 +448,11 @@
       "integrity": "sha1-l4hXRCxEdJ5CBmE+N5RiBYJqvYA="
     },
     "dns-suite": {
-      "version": "git+https://git@git.daplie.com/Daplie/dns-suite#950867c452323da776c050363b22d8f06a8ed414"
+      "version": "git+https://git@git.daplie.com/Daplie/dns-suite#6352cf4b516d94f0283c9c7cd024431bf974f049",
+      "requires": {
+        "bluebird": "3.5.0",
+        "hexdump.js": "1.0.5"
+      }
     },
     "duplexer2": {
       "version": "0.1.4",
@@ -820,6 +824,11 @@
         "sntp": "1.0.9"
       }
     },
+    "hexdump.js": {
+      "version": "1.0.5",
+      "resolved": "https://registry.npmjs.org/hexdump.js/-/hexdump.js-1.0.5.tgz",
+      "integrity": "sha1-xbxlSoIvAzjzEX5fXzVgZd6HmDQ="
+    },
     "hmac-drbg": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/hmac-drbg/-/hmac-drbg-1.0.1.tgz",