added simple mDNS responder

bin/goldilocks.js

@@ -73,6 +73,9 @@ function readConfigAndRun(args) {
   if (!config.dns) {
     config.dns = { modules: { name: 'proxy', port: 3053 } };
   }
+  if (!config.mdns) {
+    config.mdns = { port: 5353, broadcast: '224.0.0.251', ttl: 300 };
+  }
   if (!config.tcp) {
     config.tcp = {};
   }

lib/goldilocks.js

@@ -225,5 +225,9 @@ module.exports.create = function (deps, config) {
     }
   }
 
+  if (!config.mdns.disabled) {
+    require('./mdns').start(deps, config);
+  }
+
   return PromiseA.all(listenPromises);
 };

lib/mdns.js

@@ -0,0 +1,144 @@
+'use strict';
+
+var PromiseA = require('bluebird');
+var fs = PromiseA.promisifyAll(require('fs'));
+var idFilename = require('path').join(__dirname, '..', 'var', 'mdns-id');
+var queryName = '_cloud._tcp.local';
+
+var randomId = {
+  get: function () {
+    return fs.readFileAsync(idFilename)
+      .catch(function (err) {
+        if (err.code !== 'ENOENT') {
+          return PromiseA.reject(err);
+        }
+        var id = require('crypto').randomBytes(5).toString('hex');
+        return randomId.set(id);
+      });
+  }
+
+, set: function (value) {
+    return fs.writeFileAsync(idFilename, value)
+      .then(function () {
+        return value;
+      });
+  }
+};
+
+function createResponse(name, packet, ttl) {
+  var rpacket = {
+    header: {
+      id: packet.header.id
+    , qr: 1
+    , opcode: 0
+    , aa: 1
+    , tc: 0
+    , rd: 0
+    , ra: 0
+    , res1:  0
+    , res2:  0
+    , res3:  0
+    , rcode: 0
+  , }
+  , question: packet.question
+  , answer: []
+  , authority: []
+  , additional: []
+  , edns_options: []
+  };
+
+  rpacket.answer.push({
+    name: queryName
+  , typeName: 'PTR'
+  , ttl: ttl
+  , className: 'IN'
+  , data: name + '.' + queryName
+  });
+
+  var ifaces = require('./local-ip').find();
+  Object.keys(ifaces).forEach(function (iname) {
+    var iface = ifaces[iname];
+
+    iface.ipv4.forEach(function (addr) {
+      rpacket.additional.push({
+        name: name + '.local'
+      , typeName: 'A'
+      , ttl: ttl
+      , className: 'IN'
+      , address: addr.address
+      });
+    });
+
+    iface.ipv6.forEach(function (addr) {
+      rpacket.additional.push({
+        name: name + '.local'
+      , typeName: 'AAAA'
+      , ttl: ttl
+      , className: 'IN'
+      , address: addr.address
+      });
+    });
+  });
+
+  rpacket.additional.push({
+    name: name + '.' + queryName
+  , typeName: 'SRV'
+  , ttl: ttl
+  , className: 'IN'
+  , priority: 1
+  , weight: 0
+  , port: 443
+  , target: name + ".local"
+  });
+  rpacket.additional.push({
+    name: name + '._device-info._tcp.local'
+  , typeName: 'TXT'
+  , ttl: ttl
+  , className: 'IN'
+  , data: ["model=CloudHome1,1", "dappsvers=1"]
+  });
+
+  return require('dns-suite').DNSPacket.write(rpacket);
+}
+
+module.exports.start = function (deps, config) {
+  var socket = require('dgram').createSocket({ type: 'udp4', reuseAddr: true });
+  var dns = require('dns-suite');
+
+  socket.on('message', function (message, rinfo) {
+    // console.log('Received %d bytes from %s:%d', message.length, rinfo.address, rinfo.port);
+
+    var packet;
+    try {
+      packet = dns.DNSPacket.parse(message);
+    }
+    catch (er) {
+      // `dns-suite` actually errors on a lot of the packets floating around in our network,
+      // so don't bother logging any errors. (We still use `dns-suite` because unlike `dns-js`
+      // it can successfully craft the one packet we want to send.)
+      return;
+    }
+
+    // Only respond to queries.
+    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;
+    }
+
+    randomId.get().then(function (name) {
+      var resp = createResponse(name, packet, config.mdns.ttl);
+      socket.send(resp, config.mdns.port, config.mdns.broadcast);
+    });
+  });
+
+  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);
+  });
+};

package.json

@@ -41,6 +41,7 @@
     "bluebird": "^3.4.6",
     "body-parser": "git+https://github.com/expressjs/body-parser.git#1.16.1",
     "commander": "^2.9.0",
+    "dns-suite": "git+https://git@git.daplie.com:Daplie/dns-suite#v1",
     "express": "git+https://github.com/expressjs/express.git#4.x",
     "finalhandler": "^0.4.0",
     "greenlock": "git+https://git.daplie.com/Daplie/node-greenlock.git#master",