lib/portfinder.js

/*
 * portfinder.js: A simple tool to find an open port on the current machine.
 *
 * (C) 2011, Charlie Robbins
 *
 */

"use strict";

var fs = require('fs'),
    os = require('os'),
    net = require('net'),
    path = require('path'),
    _async = require('async'),
    debug = require('debug'),
    mkdirp = require('mkdirp').mkdirp;

var debugTestPort = debug('portfinder:testPort'),
    debugGetPort = debug('portfinder:getPort'),
    debugDefaultHosts = debug('portfinder:defaultHosts');

var internals = {};

internals.testPort = function(options, callback) {
  if (!callback) {
    callback = options;
    options = {};
  }

  options.server = options.server  || net.createServer(function () {
    //
    // Create an empty listener for the port testing server.
    //
  });

  debugTestPort("entered testPort(): trying", options.host, "port", options.port);

  function onListen () {
    debugTestPort("done w/ testPort(): OK", options.host, "port", options.port);

    options.server.removeListener('error', onError);
    options.server.close();
    callback(null, options.port);
  }

  function onError (err) {
    debugTestPort("done w/ testPort(): failed", options.host, "w/ port", options.port, "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 (nextPort > exports.highestPort) {
      return callback(new Error('No open ports available'));
    }

    internals.testPort({
      port: nextPort,
      host: options.host,
      server: options.server
    }, callback);
  }

  options.server.once('error', onError);
  options.server.once('listening', onListen);

  if (options.host) {
    options.server.listen(options.port, options.host);
  } else {
    /*
      Judgement of service without host
      example:
        express().listen(options.port)
    */
    options.server.listen(options.port);
  }
};

//
// ### @basePort {Number}
// The lowest port to begin any port search from
//
exports.basePort = 8000;

//
// ### function setBasePort (port)
// #### @port {Number} The new base port
//
exports.setBasePort = function (port) {
  exports.basePort = port;
}

//
// ### @highestPort {Number}
// Largest port number is an unsigned short 2**16 -1=65335
//
exports.highestPort = 65535;

//
// ### function setHighestPort (port)
// #### @port {Number} The new highest port
//
exports.setHighestPort = function (port) {
  exports.highestPort = port;
}

//
// ### @basePath {string}
// Default path to begin any socket search from
//
exports.basePath = '/tmp/portfinder'

//
// ### function getPort (options, callback)
// #### @options {Object} Settings to use when finding the necessary port
// #### @callback {function} Continuation to respond to when complete.
// Responds with a unbound port on the current machine.
//
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);

  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.host) {
    if (exports._defaultHosts.indexOf(options.host) !== -1) {
      exports._defaultHosts.push(options.host)
    }
  }

  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) {
      if (err) {
        debugGetPort("in eachSeries() iteration callback testPort() callback", "with an err:", err.code);
        currentHost = host;
        return next(err);
      } else {
        debugGetPort("in eachSeries() iteration callback testPort() callback",
                    "with a success for port", port);
        openPorts.push(port);
        return next();
      }
    });
  }, function(err) {

    if (err) {
      debugGetPort("in eachSeries() result callback: err is", err);
      // If we get EADDRNOTAVAIL it means the host is not bindable, so remove it
      // from exports._defaultHosts and start over. For ubuntu, we use EINVAL for the same
      if (err.code === 'EADDRNOTAVAIL' || err.code === 'EINVAL') {
        if (options.host === currentHost) {
          // if bad address matches host given by user, tell them
          //
          // NOTE: We may need to one day handle `my-non-existent-host.local` if users
          // report frustration with passing in hostnames that DONT map to bindable
          // hosts, without showing them a good error.
          var msg = 'Provided host ' + options.host + ' could NOT be bound. Please provide a different host address or hostname';
          return callback(Error(msg));
        } else {
          var idx = exports._defaultHosts.indexOf(currentHost);
          exports._defaultHosts.splice(idx, 1);
          return exports.getPort(options, callback);
        }
      } else {
        // error is not accounted for, file ticket, handle special case
        return callback(err);
      }
    }

    // sort so we can compare first host to last host
    openPorts.sort(function(a, b) {
      return a - b;
    });

    debugGetPort("in eachSeries() result callback: openPorts is", openPorts);

    if (openPorts[0] === openPorts[openPorts.length-1]) {
      // if first === last, we found an open port
      if(openPorts[0] <= options.stopPort) {
        return callback(null, openPorts[0]);
      }
      else {
        var msg = 'No open ports found in between '+ options.startPort + ' and ' + options.stopPort;
        return callback(Error(msg));
      }
    } else {
      // otherwise, try again, using sorted port, aka, highest open for >= 1 host
      return exports.getPort({ port: openPorts.pop(), host: options.host, startPort: options.startPort, stopPort: options.stopPort }, callback);
    }

  });
};

//
// ### function getPortPromise (options)
// #### @options {Object} Settings to use when finding the necessary port
// Responds a promise to an unbound port on the current machine.
//
exports.getPortPromise = function (options) {
  if (typeof Promise !== 'function') {
    throw Error('Native promise support is not available in this version of node.' +
      'Please install a polyfill and assign Promise to global.Promise before calling this method');
  }
  if (!options) {
    options = {};
  }
  return new Promise(function(resolve, reject) {
    exports.getPort(options, function(err, port) {
      if (err) {
        return reject(err);
      }
      resolve(port);
    });
  });
}

//
// ### function getPorts (count, options, callback)
// #### @count {Number} The number of ports to find
// #### @options {Object} Settings to use when finding the necessary port
// #### @callback {function} Continuation to respond to when complete.
// Responds with an array of unbound ports on the current machine.
//
exports.getPorts = function (count, options, callback) {
  if (!callback) {
    callback = options;
    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);
      }
    });
  }, callback);
};

//
// ### function getSocket (options, callback)
// #### @options {Object} Settings to use when finding the necessary port
// #### @callback {function} Continuation to respond to when complete.
// Responds with a unbound socket using the specified directory and base
// name on the current machine.
//
exports.getSocket = function (options, callback) {
  if (!callback) {
    callback = options;
    options = {};
  }

  options.mod  = options.mod    || parseInt(755, 8);
  options.path = options.path   || exports.basePath + '.sock';

  //
  // Tests the specified socket
  //
  function testSocket () {
    fs.stat(options.path, function (err) {
      //
      // If file we're checking doesn't exist (thus, stating it emits ENOENT),
      // we should be OK with listening on this socket.
      //
      if (err) {
        if (err.code == 'ENOENT') {
          callback(null, options.path);
        }
        else {
          callback(err);
        }
      }
      else {
        //
        // This file exists, so it isn't possible to listen on it. Lets try
        // next socket.
        //
        options.path = exports.nextSocket(options.path);
        exports.getSocket(options, callback);
      }
    });
  }

  //
  // Create the target `dir` then test connection
  // against the socket.
  //
  function createAndTestSocket (dir) {
    mkdirp(dir, options.mod, function (err) {
      if (err) {
        return callback(err);
      }

      options.exists = true;
      testSocket();
    });
  }

  //
  // Check if the parent directory of the target
  // socket path exists. If it does, test connection
  // against the socket. Otherwise, create the directory
  // then test connection.
  //
  function checkAndTestSocket () {
    var dir = path.dirname(options.path);

    fs.stat(dir, function (err, stats) {
      if (err || !stats.isDirectory()) {
        return createAndTestSocket(dir);
      }

      options.exists = true;
      testSocket();
    });
  }

  //
  // If it has been explicitly stated that the
  // target `options.path` already exists, then
  // simply test the socket.
  //
  return options.exists
    ? testSocket()
    : checkAndTestSocket();
};

//
// ### function nextPort (port)
// #### @port {Number} Port to increment from.
// Gets the next port in sequence from the
// specified `port`.
//
exports.nextPort = function (port) {
  return port + 1;
};

//
// ### function nextSocket (socketPath)
// #### @socketPath {string} Path to increment from
// Gets the next socket path in sequence from the
// specified `socketPath`.
//
exports.nextSocket = function (socketPath) {
  var dir = path.dirname(socketPath),
      name = path.basename(socketPath, '.sock'),
      match = name.match(/^([a-zA-z]+)(\d*)$/i),
      index = parseInt(match[2]),
      base = match[1];
  if (isNaN(index)) {
    index = 0;
  }

  index += 1;
  return path.join(dir, base + index + '.sock');
};

/**
 * @desc List of internal hostnames provided by your machine. A user
 *       provided hostname may also be provided when calling portfinder.getPort,
 *       which would then be added to the default hosts we lookup and return here.
 *
 * @return {array}
 *
 * Long Form Explantion:
 *
 *    - Input: (os.networkInterfaces() w/ MacOS 10.11.5+ and running a VM)
 *
 *        { lo0:
 *         [ { address: '::1',
 *             netmask: 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff',
 *             family: 'IPv6',
 *             mac: '00:00:00:00:00:00',
 *             scopeid: 0,
 *             internal: true },
 *           { address: '127.0.0.1',
 *             netmask: '255.0.0.0',
 *             family: 'IPv4',
 *             mac: '00:00:00:00:00:00',
 *             internal: true },
 *           { address: 'fe80::1',
 *             netmask: 'ffff:ffff:ffff:ffff::',
 *             family: 'IPv6',
 *             mac: '00:00:00:00:00:00',
 *             scopeid: 1,
 *             internal: true } ],
 *        en0:
 *         [ { address: 'fe80::a299:9bff:fe17:766d',
 *             netmask: 'ffff:ffff:ffff:ffff::',
 *             family: 'IPv6',
 *             mac: 'a0:99:9b:17:76:6d',
 *             scopeid: 4,
 *             internal: false },
 *           { address: '10.0.1.22',
 *             netmask: '255.255.255.0',
 *             family: 'IPv4',
 *             mac: 'a0:99:9b:17:76:6d',
 *             internal: false } ],
 *        awdl0:
 *         [ { address: 'fe80::48a8:37ff:fe34:aaef',
 *             netmask: 'ffff:ffff:ffff:ffff::',
 *             family: 'IPv6',
 *             mac: '4a:a8:37:34:aa:ef',
 *             scopeid: 8,
 *             internal: false } ],
 *        vnic0:
 *         [ { address: '10.211.55.2',
 *             netmask: '255.255.255.0',
 *             family: 'IPv4',
 *             mac: '00:1c:42:00:00:08',
 *             internal: false } ],
 *        vnic1:
 *         [ { address: '10.37.129.2',
 *             netmask: '255.255.255.0',
 *             family: 'IPv4',
 *             mac: '00:1c:42:00:00:09',
 *             internal: false } ] }
 *
 *    - Output:
 *
 *         [
 *          '0.0.0.0',
 *          '::1',
 *          '127.0.0.1',
 *          'fe80::1',
 *          '10.0.1.22',
 *          'fe80::48a8:37ff:fe34:aaef',
 *          '10.211.55.2',
 *          '10.37.129.2'
 *         ]
 *
 *     Note we export this so we can use it in our tests, otherwise this API is private
 */
exports._defaultHosts = (function() {
  var interfaces = {};
  try{
    interfaces = os.networkInterfaces();
  }
  catch(e) {
    // As of October 2016, Windows Subsystem for Linux (WSL) does not support
    // the os.networkInterfaces() call and throws instead. For this platform,
    // assume 0.0.0.0 as the only address
    //
    // - https://github.com/Microsoft/BashOnWindows/issues/468
    //
    // - Workaround is a mix of good work from the community:
    //   - https://github.com/http-party/node-portfinder/commit/8d7e30a648ff5034186551fa8a6652669dec2f2f
    //   - https://github.com/yarnpkg/yarn/pull/772/files
    if (e.syscall === 'uv_interface_addresses') {
      // swallow error because we're just going to use defaults
      // documented @ https://github.com/nodejs/node/blob/4b65a65e75f48ff447cabd5500ce115fb5ad4c57/doc/api/net.md#L231
    } else {
      throw e;
    }
  }

  var interfaceNames = Object.keys(interfaces),
      hiddenButImportantHost = '0.0.0.0', // !important - dont remove, hence the naming :)
      results = [hiddenButImportantHost];
  for (var i = 0; i < interfaceNames.length; i++) {
    var _interface = interfaces[interfaceNames[i]];
    for (var j = 0; j < _interface.length; j++) {
      var curr = _interface[j];
      results.push(curr.address);
    }
  }

  // add null value, For createServer function, do not use host.
  results.push(null);

  debugDefaultHosts("exports._defaultHosts is: %o", results);

  return results;
}());