net/portprober.js

1// Licensed to the Software Freedom Conservancy (SFC) under one
2// or more contributor license agreements. See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership. The SFC licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License. You may obtain a copy of the License at
8//
9// http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied. See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18'use strict';
19
20var exec = require('child_process').exec,
21 fs = require('fs'),
22 net = require('net');
23
24var promise = require('../index').promise;
25
26
27/**
28 * The IANA suggested ephemeral port range.
29 * @type {{min: number, max: number}}
30 * @const
31 * @see http://en.wikipedia.org/wiki/Ephemeral_ports
32 */
33var DEFAULT_IANA_RANGE = {min: 49152, max: 65535};
34
35
36/**
37 * The epheremal port range for the current system. Lazily computed on first
38 * access.
39 * @type {webdriver.promise.Promise.<{min: number, max: number}>}
40 */
41var systemRange = null;
42
43
44/**
45 * Computes the ephemeral port range for the current system. This is based on
46 * http://stackoverflow.com/a/924337.
47 * @return {webdriver.promise.Promise.<{min: number, max: number}>} A promise
48 * that will resolve to the ephemeral port range of the current system.
49 */
50function findSystemPortRange() {
51 if (systemRange) {
52 return systemRange;
53 }
54 var range = process.platform === 'win32' ?
55 findWindowsPortRange() : findUnixPortRange();
56 return systemRange = range.thenCatch(function() {
57 return DEFAULT_IANA_RANGE;
58 });
59}
60
61
62/**
63 * Executes a command and returns its output if it succeeds.
64 * @param {string} cmd The command to execute.
65 * @return {!webdriver.promise.Promise.<string>} A promise that will resolve
66 * with the command's stdout data.
67 */
68function execute(cmd) {
69 var result = promise.defer();
70 exec(cmd, function(err, stdout) {
71 if (err) {
72 result.reject(err);
73 } else {
74 result.fulfill(stdout);
75 }
76 });
77 return result.promise;
78}
79
80
81/**
82 * Computes the ephemeral port range for a Unix-like system.
83 * @return {!webdriver.promise.Promise.<{min: number, max: number}>} A promise
84 * that will resolve with the ephemeral port range on the current system.
85 */
86function findUnixPortRange() {
87 var cmd;
88 if (process.platform === 'sunos') {
89 cmd =
90 '/usr/sbin/ndd /dev/tcp tcp_smallest_anon_port tcp_largest_anon_port';
91 } else if (fs.existsSync('/proc/sys/net/ipv4/ip_local_port_range')) {
92 // Linux
93 cmd = 'cat /proc/sys/net/ipv4/ip_local_port_range';
94 } else {
95 cmd = 'sysctl net.inet.ip.portrange.first net.inet.ip.portrange.last' +
96 ' | sed -e "s/.*:\\s*//"';
97 }
98
99 return execute(cmd).then(function(stdout) {
100 if (!stdout || !stdout.length) return DEFAULT_IANA_RANGE;
101 var range = stdout.trim().split(/\s+/).map(Number);
102 if (range.some(isNaN)) return DEFAULT_IANA_RANGE;
103 return {min: range[0], max: range[1]};
104 });
105}
106
107
108/**
109 * Computes the ephemeral port range for a Windows system.
110 * @return {!webdriver.promise.Promise.<{min: number, max: number}>} A promise
111 * that will resolve with the ephemeral port range on the current system.
112 */
113function findWindowsPortRange() {
114 var deferredRange = promise.defer();
115 // First, check if we're running on XP. If this initial command fails,
116 // we just fallback on the default IANA range.
117 return execute('cmd.exe /c ver').then(function(stdout) {
118 if (/Windows XP/.test(stdout)) {
119 // TODO: Try to read these values from the registry.
120 return {min: 1025, max: 5000};
121 } else {
122 return execute('netsh int ipv4 show dynamicport tcp').
123 then(function(stdout) {
124 /* > netsh int ipv4 show dynamicport tcp
125 Protocol tcp Dynamic Port Range
126 ---------------------------------
127 Start Port : 49152
128 Number of Ports : 16384
129 */
130 var range = stdout.split(/\n/).filter(function(line) {
131 return /.*:\s*\d+/.test(line);
132 }).map(function(line) {
133 return Number(line.split(/:\s*/)[1]);
134 });
135
136 return {
137 min: range[0],
138 max: range[0] + range[1]
139 };
140 });
141 }
142 });
143}
144
145
146/**
147 * Tests if a port is free.
148 * @param {number} port The port to test.
149 * @param {string=} opt_host The bound host to test the {@code port} against.
150 * Defaults to {@code INADDR_ANY}.
151 * @return {!webdriver.promise.Promise.<boolean>} A promise that will resolve
152 * with whether the port is free.
153 */
154function isFree(port, opt_host) {
155 var result = promise.defer(function() {
156 server.cancel();
157 });
158
159 var server = net.createServer().on('error', function(e) {
160 if (e.code === 'EADDRINUSE') {
161 result.fulfill(false);
162 } else {
163 result.reject(e);
164 }
165 });
166
167 server.listen(port, opt_host, function() {
168 server.close(function() {
169 result.fulfill(true);
170 });
171 });
172
173 return result.promise;
174}
175
176
177/**
178 * @param {string=} opt_host The bound host to test the {@code port} against.
179 * Defaults to {@code INADDR_ANY}.
180 * @return {!webdriver.promise.Promise.<number>} A promise that will resolve
181 * to a free port. If a port cannot be found, the promise will be
182 * rejected.
183 */
184function findFreePort(opt_host) {
185 return findSystemPortRange().then(function(range) {
186 var attempts = 0;
187 var deferredPort = promise.defer();
188 findPort();
189 return deferredPort.promise;
190
191 function findPort() {
192 attempts += 1;
193 if (attempts > 10) {
194 deferredPort.reject(Error('Unable to find a free port'));
195 }
196
197 var port = Math.floor(
198 Math.random() * (range.max - range.min) + range.min);
199 isFree(port, opt_host).then(function(isFree) {
200 if (isFree) {
201 deferredPort.fulfill(port);
202 } else {
203 findPort();
204 }
205 });
206 }
207 });
208}
209
210
211// PUBLIC API
212
213
214exports.findFreePort = findFreePort;
215exports.isFree = isFree;