--- /dev/null
+// Copyright 2013 Selenium committers
+// Copyright 2013 Software Freedom Conservancy
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+'use strict';
+
+var exec = require('child_process').exec,
+ fs = require('fs'),
+ net = require('net');
+
+var promise = require('../index').promise;
+
+
+/**
+ * The IANA suggested ephemeral port range.
+ * @type {{min: number, max: number}}
+ * @const
+ * @see http://en.wikipedia.org/wiki/Ephemeral_ports
+ */
+var DEFAULT_IANA_RANGE = {min: 49152, max: 65535};
+
+
+/**
+ * The epheremal port range for the current system. Lazily computed on first
+ * access.
+ * @type {webdriver.promise.Promise.<{min: number, max: number}>}
+ */
+var systemRange = null;
+
+
+/**
+ * Computes the ephemeral port range for the current system. This is based on
+ * http://stackoverflow.com/a/924337.
+ * @return {webdriver.promise.Promise.<{min: number, max: number}>} A promise
+ * that will resolve to the ephemeral port range of the current system.
+ */
+function findSystemPortRange() {
+ if (systemRange) {
+ return systemRange;
+ }
+ var range = process.platform === 'win32' ?
+ findWindowsPortRange() : findUnixPortRange();
+ return systemRange = range.thenCatch(function() {
+ return DEFAULT_IANA_RANGE;
+ });
+}
+
+
+/**
+ * Executes a command and returns its output if it succeeds.
+ * @param {string} cmd The command to execute.
+ * @return {!webdriver.promise.Promise.<string>} A promise that will resolve
+ * with the command's stdout data.
+ */
+function execute(cmd) {
+ var result = promise.defer();
+ exec(cmd, function(err, stdout) {
+ if (err) {
+ result.reject(err);
+ } else {
+ result.fulfill(stdout);
+ }
+ });
+ return result.promise;
+}
+
+
+/**
+ * Computes the ephemeral port range for a Unix-like system.
+ * @return {!webdriver.promise.Promise.<{min: number, max: number}>} A promise
+ * that will resolve with the ephemeral port range on the current system.
+ */
+function findUnixPortRange() {
+ var cmd;
+ if (process.platform === 'sunos') {
+ cmd =
+ '/usr/sbin/ndd /dev/tcp tcp_smallest_anon_port tcp_largest_anon_port';
+ } else if (fs.existsSync('/proc/sys/net/ipv4/ip_local_port_range')) {
+ // Linux
+ cmd = 'cat /proc/sys/net/ipv4/ip_local_port_range';
+ } else {
+ cmd = 'sysctl net.inet.ip.portrange.first net.inet.ip.portrange.last' +
+ ' | sed -e "s/.*:\\s*//"';
+ }
+
+ return execute(cmd).then(function(stdout) {
+ if (!stdout || !stdout.length) return DEFAULT_IANA_RANGE;
+ var range = stdout.trim().split(/\s+/).map(Number);
+ if (range.some(isNaN)) return DEFAULT_IANA_RANGE;
+ return {min: range[0], max: range[1]};
+ });
+}
+
+
+/**
+ * Computes the ephemeral port range for a Windows system.
+ * @return {!webdriver.promise.Promise.<{min: number, max: number}>} A promise
+ * that will resolve with the ephemeral port range on the current system.
+ */
+function findWindowsPortRange() {
+ var deferredRange = promise.defer();
+ // First, check if we're running on XP. If this initial command fails,
+ // we just fallback on the default IANA range.
+ return execute('cmd.exe /c ver').then(function(stdout) {
+ if (/Windows XP/.test(stdout)) {
+ // TODO: Try to read these values from the registry.
+ return {min: 1025, max: 5000};
+ } else {
+ return execute('netsh int ipv4 show dynamicport tcp').
+ then(function(stdout) {
+ /* > netsh int ipv4 show dynamicport tcp
+ Protocol tcp Dynamic Port Range
+ ---------------------------------
+ Start Port : 49152
+ Number of Ports : 16384
+ */
+ var range = stdout.split(/\n/).filter(function(line) {
+ return /.*:\s*\d+/.test(line);
+ }).map(function(line) {
+ return Number(line.split(/:\s*/)[1]);
+ });
+
+ return {
+ min: range[0],
+ max: range[0] + range[1]
+ };
+ });
+ }
+ });
+}
+
+
+/**
+ * Tests if a port is free.
+ * @param {number} port The port to test.
+ * @param {string=} opt_host The bound host to test the {@code port} against.
+ * Defaults to {@code INADDR_ANY}.
+ * @return {!webdriver.promise.Promise.<boolean>} A promise that will resolve
+ * with whether the port is free.
+ */
+function isFree(port, opt_host) {
+ var result = promise.defer(function() {
+ server.cancel();
+ });
+
+ var server = net.createServer().on('error', function(e) {
+ if (e.code === 'EADDRINUSE') {
+ result.fulfill(false);
+ } else {
+ result.reject(e);
+ }
+ });
+
+ server.listen(port, opt_host, function() {
+ server.close(function() {
+ result.fulfill(true);
+ });
+ });
+
+ return result.promise;
+}
+
+
+/**
+ * @param {string=} opt_host The bound host to test the {@code port} against.
+ * Defaults to {@code INADDR_ANY}.
+ * @return {!webdriver.promise.Promise.<number>} A promise that will resolve
+ * to a free port. If a port cannot be found, the promise will be
+ * rejected.
+ */
+function findFreePort(opt_host) {
+ return findSystemPortRange().then(function(range) {
+ var attempts = 0;
+ var deferredPort = promise.defer();
+ findPort();
+ return deferredPort.promise;
+
+ function findPort() {
+ attempts += 1;
+ if (attempts > 10) {
+ deferredPort.reject(Error('Unable to find a free port'));
+ }
+
+ var port = Math.floor(
+ Math.random() * (range.max - range.min) + range.min);
+ isFree(port, opt_host).then(function(isFree) {
+ if (isFree) {
+ deferredPort.fulfill(port);
+ } else {
+ findPort();
+ }
+ });
+ }
+ });
+}
+
+
+// PUBLIC API
+
+
+exports.findFreePort = findFreePort;
+exports.isFree = isFree;
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