moved the handling of udp stuff to a separate file

lib/goldilocks.js

@@ -159,27 +159,6 @@ module.exports.create = function (deps, config) {
     });
   }
 
-  function udpHandler(port, msg) {
-    if (!Array.isArray(config.udp.modules)) {
-      return;
-    }
-    var socket = require('dgram').createSocket('udp4');
-    config.udp.modules.forEach(function (mod) {
-      if (mod.type !== 'forward') {
-        console.warn('found bad DNS module', mod);
-        return;
-      }
-      if (mod.ports.indexOf(port) < 0) {
-        return;
-      }
-
-      var dest = require('./domain-utils').separatePort(mod.address || '');
-      dest.port = dest.port || mod.port;
-      dest.host = dest.host || mod.host || 'localhost';
-      socket.send(msg, dest.port, dest.host);
-    });
-  }
-
   function createTcpForwarder(mod) {
     var dest = require('./domain-utils').separatePort(mod.address || '');
     dest.port = dest.port || mod.port;
@@ -289,12 +268,6 @@ module.exports.create = function (deps, config) {
     listenPromises.push(listeners.tcp.add(port, tcpHandler));
   });
 
-  if (config.udp.bind) {
-    config.udp.bind.forEach(function (port) {
-      listenPromises.push(listeners.udp.add(port, udpHandler.bind(port)));
-    });
-  }
-
   if (!config.mdns.disabled) {
     require('./mdns').start(deps, config, portList[0]);
   }

lib/udp.js

@@ -0,0 +1,57 @@
+'use strict';
+
+module.exports.create = function (deps, config) {
+  var listeners = require('./servers').listeners.udp;
+
+  function packetHandler(port, msg) {
+    if (!Array.isArray(config.udp.modules)) {
+      return;
+    }
+
+    var socket = require('dgram').createSocket('udp4');
+    config.udp.modules.forEach(function (mod) {
+      if (mod.type !== 'forward') {
+        // To avoid logging bad modules every time we get a UDP packet we assign a warned
+        // property to the module (non-enumerable so it won't be saved to the config or
+        // show up in the API).
+        if (!mod.warned) {
+          console.warn('found bad DNS module', mod);
+          Object.defineProperty(mod, 'warned', {value: true, enumerable: false});
+        }
+        return;
+      }
+      if (mod.ports.indexOf(port) < 0) {
+        return;
+      }
+
+      var dest = require('./domain-utils').separatePort(mod.address || '');
+      dest.port = dest.port || mod.port;
+      dest.host = dest.host || mod.host || 'localhost';
+      socket.send(msg, dest.port, dest.host);
+    });
+  }
+
+  function updateListeners() {
+    var current = listeners.list();
+    var wanted = config.udp.bind;
+
+    if (!Array.isArray(wanted)) { wanted = []; }
+    wanted = wanted.map(Number).filter((port) => port > 0 && port < 65356);
+
+    current.forEach(function (port) {
+      if (wanted.indexOf(port) < 0) {
+        listeners.close(port);
+      }
+    });
+    wanted.forEach(function (port) {
+      if (current.indexOf(port) < 0) {
+        listeners.add(port, packetHandler.bind(port));
+      }
+    });
+  }
+
+  updateListeners();
+  return {
+    updateConf: updateListeners
+  };
+};

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)
+  , udp:      require('./udp').create(deps, conf)
   };
   Object.assign(deps, modules);