Avoid breaking existing consumers who use startPort >= 40000

README.md

@@ -1,4 +1,4 @@
-# node-portfinder [![Build Status](https://api.travis-ci.org/indexzero/node-portfinder.svg)](https://travis-ci.org/indexzero/node-portfinder)
+# node-portfinder [![Build Status](https://api.travis-ci.org/http-party/node-portfinder.svg)](https://travis-ci.org/http-party/node-portfinder)
 
 ## Installation
 
@@ -43,13 +43,13 @@ If `portfinder.getPortPromise()` is called on a Node version without Promise (<4
 
 ### Ports search scope 
 
-By default `portfinder` will start searching from `8000` and scan until maximum port number (`65535`) is reached. 
+By default `portfinder` will start searching from `8000` and scan until maximum port number (`40000`) is reached. `40000` is the highest safe port across platforms. If you are not on OSX, you can safely override the max port up to 65535.
 
 You can change this globally by setting:
 
 ```js
 portfinder.basePort = 3000;    // default: 8000
-portfinder.highestPort = 3333; // default: 65535
+portfinder.highestPort = 3333; // default: 40000; cannot be overriden above 65535
 ```
 
 or by passing optional options object on each invocation:
@@ -61,6 +61,16 @@ portfinder.getPort({
 }, callback);
 ```
 
+### Port scan strategy
+
+By default, portfinder will perform a linear scan from the startPort to the stopPort until it has found a free port (or the number of free ports specified in `getPorts`). This can lead to race conditions if `getPort` is called several times in quick succession: the same port may be returned for multiple calls. To avoid this, you can pass `useRandom: true` into the options, in which case ports in the range from `startPort` to `stopPort` will be checked in random order:
+
+```js
+portfinder.getPort({
+    useRandom: true
+}, callback);
+```
+
 ## Run Tests
 ``` bash
   $ npm test

lib/portfinder.js

@@ -33,50 +33,55 @@ internals.testPort = function(options, callback) {
     //
   });
 
-  debugTestPort("entered testPort(): trying", options.host, "port", options.port);
+  var candidatePorts = options.ports.slice()
+  var currentPort  = candidatePorts.pop()
+
+  debugTestPort("entered testPort(): trying", options.host, "port", currentPort);
 
   function onListen () {
-    debugTestPort("done w/ testPort(): OK", options.host, "port", options.port);
+    debugTestPort("done w/ testPort(): OK", options.host, "port", currentPort);
 
         options.server.removeListener('error', onError);
         options.server.close();
-      callback(null, options.port);
+      callback(null, currentPort);
   }
 
   function onError (err) {
-    debugTestPort("done w/ testPort(): failed", options.host, "w/ port", options.port, "with error", err.code);
+    debugTestPort("done w/ testPort(): failed", options.host, "w/ port", currentPort, "with error", err.code);
 
     options.server.removeListener('listening', onListen);
 
     if (!(err.code == 'EADDRINUSE' || err.code == 'EACCES')) {
       return callback(err);
     }
 
-    var nextPort = exports.nextPort(options.port);
+    if (candidatePorts.length === 0) {
+      var msg = 'No open ports found in between ' + options.startPort + ' and ' + options.stopPort; 
+      return callback(new Error(msg));
 
-    if (nextPort > exports.highestPort) {
-      return callback(new Error('No open ports available'));
     }
 
     internals.testPort({
-      port: nextPort,
+      ports: candidatePorts,
       host: options.host,
-      server: options.server
+      server: options.server,
+      startPort: options.startPort,
+      stopPort: options.stopPort
     }, callback);
   }
 
   options.server.once('error', onError);
   options.server.once('listening', onListen);
 
   if (options.host) {
-    options.server.listen(options.port, options.host);
+    options.server.listen(currentPort, options.host);
   } else {
     /*
       Judgement of service without host
       example:
         express().listen(options.port)
     */
-    options.server.listen(options.port);
+    options.server.listen(currentPort);
   }
 };
 
@@ -89,8 +94,13 @@ exports.basePort = 8000;
 //
 // ### @highestPort {Number}
 // Largest port number is an unsigned short 2**16 -1=65335
+// To avoid collisions with the MacBook Pro touchbar, which binds
+// to a random port in the range 40,000 - ~60,000, we only search
+// up to 40,000 unless the user explicitly specifies a stopPort higher 
+// than that. In any event, we will not search above _highestPort (65535).
 //
-exports.highestPort = 65535;
+exports.highestPort = 40000; // The safe highest port; user can override to search higher
+var _highestPort = 65535; // The absolute highest port;
 
 //
 // ### @basePath {string}
@@ -108,23 +118,39 @@ exports.getPort = function (options, callback) {
   if (!callback) {
     callback = options;
     options = {};
-
   }
-
   options.port   = Number(options.port) || Number(exports.basePort);
-  options.host   = options.host    || null;
-  options.stopPort = Number(options.stopPort) || Number(exports.highestPort);
+  options.host   = options.host || null;
+
+  // Validate startPort and stopPort
+  if (!options.stopPort) {
+    options.stopPort = Number(exports.highestPort);
+  } else {
+    options.stopPort = Math.min(Number(options.stopPort), Number(_highestPort))
+  }
 
   if(!options.startPort) {
     options.startPort = Number(options.port);
     if(options.startPort < 0) {
       throw Error('Provided options.startPort(' + options.startPort + ') is less than 0, which are cannot be bound.');
     }
-    if(options.stopPort < options.startPort) {
-      throw Error('Provided options.stopPort(' + options.stopPort + 'is less than options.startPort (' + options.startPort + ')');
+  }
+
+  if (options.startPort > _highestPort) {
+    throw Error('Provided options.startPort(' + options.startPort + ') is higher than the maximum available port (' + _highestPort + ').');
+  }
+
+  if (options.startPort > exports.highestPort) {
+    console.warn('Provided options.startPort(' + options.startPort + ') is higher than the recommended stopPort (' + exports.stopPort + '). This may cause issues on some systems');
+    if(options.stopPort <= options.startPort) {
+      options.stopPort = _highestPort
     }
   }
 
+  if(options.stopPort < options.startPort) {
+    throw Error('Provided options.stopPort(' + options.stopPort + 'is less than options.startPort (' + options.startPort + ')');
+  }
+
   if (options.host) {
 
     var hasUserGivenHost;
@@ -141,11 +167,21 @@ exports.getPort = function (options, callback) {
 
   }
 
+  var candidatePorts = []
+  for (i = options.port; i < options.stopPort; i++) {
+    candidatePorts.push(i)
+  }
+
+  if (options.useRandom) {
+    randomShuffle(candidatePorts)
+  } else {
+    candidatePorts.reverse()
+  }
   var openPorts = [], currentHost;
   return async.eachSeries(exports._defaultHosts, function(host, next) {
     debugGetPort("in eachSeries() iteration callback: host is", host);
 
-    return internals.testPort({ host: host, port: options.port }, function(err, port) {
+    return internals.testPort({ host: host, ports: candidatePorts, startPort: options.startPort, stopPort: options.stopPort }, function(err, port) {
       if (err) {
         debugGetPort("in eachSeries() iteration callback testPort() callback", "with an err:", err.code);
         currentHost = host;
@@ -243,17 +279,11 @@ exports.getPorts = function (count, options, callback) {
     options = {};
   }
 
-  var lastPort = null;
   async.timesSeries(count, function(index, asyncCallback) {
-    if (lastPort) {
-      options.port = exports.nextPort(lastPort);
-    }
-
     exports.getPort(options, function (err, port) {
       if (err) {
         asyncCallback(err);
       } else {
-        lastPort = port;
         asyncCallback(null, port);
       }
     });
@@ -349,14 +379,19 @@ exports.getSocket = function (options, callback) {
 };
 
 //
-// ### function nextPort (port)
-// #### @port {Number} Port to increment from.
-// Gets the next port in sequence from the
-// specified `port`.
+// ### function RandomShuffle (array)
+// #### @array {Array} array (of ports) to shuffle.
+// Uses the Fisher-Yates algorithm to randomly shuffle
+// the array in linear time. This is performed in-place.
 //
-exports.nextPort = function (port) {
-  return port + 1;
-};
+function randomShuffle(array) {
+  for (var i = array.length - 1; i > 0; i--) {
+    var j = Math.floor(Math.random() * (i + 1));
+    var tmp = array[i]
+    array[i] = array[j]
+    array[j] = tmp
+  }
+}
 
 //
 // ### function nextSocket (socketPath)

package.json

@@ -1,7 +1,7 @@
 {
   "name": "portfinder",
   "description": "A simple tool to find an open port on the current machine",
-  "version": "1.0.21",
+  "version": "1.0.22",
   "author": "Charlie Robbins <[email protected]>",
   "repository": {
     "type": "git",

test/port-finder-multiple-test.js

@@ -25,14 +25,19 @@ vows.describe('portfinder').addBatch({
       topic: function () {
         testHelper(servers, this.callback);
       },
-      "the getPorts() method with an argument of 3": {
+      "the getPorts() method with an argument of 3 and useRandom: true": {
         topic: function () {
-          portfinder.getPorts(3, this.callback);
+          portfinder.getPorts(3, {useRandom: true}, this.callback);
         },
-        "should respond with the first three available ports (32773, 32774, 32775)": function (err, ports) {
+        "should respond with three distinct available ports (>= 32773)": function (err, ports) {
           if (err) { debugVows(err); }
           assert.isTrue(!err);
-          assert.deepEqual(ports, [32773, 32774, 32775]);
+          var seen = new Set()
+          for (var port of ports) {
+            assert.isFalse(seen.has(port))
+            assert.isTrue(port >= 32773)
+            seen.add(port)
+          }
         }
       }
     }
@@ -47,14 +52,19 @@ vows.describe('portfinder').addBatch({
 
         return null;
       },
-      "the getPorts() method with an argument of 3": {
+      "the getPorts() method with an argument of 3 and useRandom: true": {
         topic: function () {
-          portfinder.getPorts(3, this.callback);
+          portfinder.getPorts(3, {useRandom: true}, this.callback);
         },
-        "should respond with the first three available ports (32768, 32769, 32770)": function (err, ports) {
+        "should respond with three distinct available ports (>= 32768)": function (err, ports) {
           if (err) { debugVows(err); }
           assert.isTrue(!err);
-          assert.deepEqual(ports, [32768, 32769, 32770]);
+          var seen = new Set()
+          for (var port of ports) {
+            assert.isFalse(seen.has(port))
+            assert.isTrue(port >= 32773)
+            seen.add(port)
+          }
         }
       }
     }