# net/portprober.js

1 | // Copyright 2013 Selenium committers
2 | // Copyright 2013 Software Freedom Conservancy
3 | //
4 | // Licensed under the Apache License, Version 2.0 (the "License");
5 | // you may not use this file except in compliance with the License.
6 | // You may obtain a copy of the License at
7 | //
8 | // http://www.apache.org/licenses/LICENSE-2.0
9 | //
10 | // Unless required by applicable law or agreed to in writing, software
11 | // distributed under the License is distributed on an "AS IS" BASIS,
12 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 | // See the License for the specific language governing permissions and
14 | // limitations under the License.
15 |
16 | 'use strict';
17 |
18 | var exec = require('child_process').exec,
19 | fs = require('fs'),
20 | net = require('net');
21 |
22 | var promise = require('../index').promise;
23 |
24 |
25 | /**
26 | * The IANA suggested ephemeral port range.
27 | * @type {{min: number, max: number}}
28 | * @const
29 | * @see http://en.wikipedia.org/wiki/Ephemeral_ports
30 | */
31 | var DEFAULT_IANA_RANGE = {min: 49152, max: 65535};
32 |
33 |
34 | /**
35 | * The epheremal port range for the current system. Lazily computed on first
36 | * access.
37 | * @type {webdriver.promise.Promise.<{min: number, max: number}>}
38 | */
39 | var systemRange = null;
40 |
41 |
42 | /**
43 | * Computes the ephemeral port range for the current system. This is based on
44 | * http://stackoverflow.com/a/924337.
45 | * @return {webdriver.promise.Promise.<{min: number, max: number}>} A promise
46 | * that will resolve to the ephemeral port range of the current system.
47 | */
48 | function findSystemPortRange() {
49 | if (systemRange) {
50 | return systemRange;
51 | }
52 | var range = process.platform === 'win32' ?
53 | findWindowsPortRange() : findUnixPortRange();
54 | return systemRange = range.thenCatch(function() {
55 | return DEFAULT_IANA_RANGE;
56 | });
57 | }
58 |
59 |
60 | /**
61 | * Executes a command and returns its output if it succeeds.
62 | * @param {string} cmd The command to execute.
63 | * @return {!webdriver.promise.Promise.<string>} A promise that will resolve
64 | * with the command's stdout data.
65 | */
66 | function execute(cmd) {
67 | var result = promise.defer();
68 | exec(cmd, function(err, stdout) {
69 | if (err) {
70 | result.reject(err);
71 | } else {
72 | result.fulfill(stdout);
73 | }
74 | });
75 | return result.promise;
76 | }
77 |
78 |
79 | /**
80 | * Computes the ephemeral port range for a Unix-like system.
81 | * @return {!webdriver.promise.Promise.<{min: number, max: number}>} A promise
82 | * that will resolve with the ephemeral port range on the current system.
83 | */
84 | function findUnixPortRange() {
85 | var cmd;
86 | if (process.platform === 'sunos') {
87 | cmd =
88 | '/usr/sbin/ndd /dev/tcp tcp_smallest_anon_port tcp_largest_anon_port';
89 | } else if (fs.existsSync('/proc/sys/net/ipv4/ip_local_port_range')) {
90 | // Linux
91 | cmd = 'cat /proc/sys/net/ipv4/ip_local_port_range';
92 | } else {
93 | cmd = 'sysctl net.inet.ip.portrange.first net.inet.ip.portrange.last' +
94 | ' | sed -e "s/.*:\\s*//"';
95 | }
96 |
97 | return execute(cmd).then(function(stdout) {
98 | if (!stdout || !stdout.length) return DEFAULT_IANA_RANGE;
99 | var range = stdout.trim().split(/\s+/).map(Number);
100 | if (range.some(isNaN)) return DEFAULT_IANA_RANGE;
101 | return {min: range[0], max: range[1]};
102 | });
103 | }
104 |
105 |
106 | /**
107 | * Computes the ephemeral port range for a Windows system.
108 | * @return {!webdriver.promise.Promise.<{min: number, max: number}>} A promise
109 | * that will resolve with the ephemeral port range on the current system.
110 | */
111 | function findWindowsPortRange() {
112 | var deferredRange = promise.defer();
113 | // First, check if we're running on XP. If this initial command fails,
114 | // we just fallback on the default IANA range.
115 | return execute('cmd.exe /c ver').then(function(stdout) {
116 | if (/Windows XP/.test(stdout)) {
117 | // TODO: Try to read these values from the registry.
118 | return {min: 1025, max: 5000};
119 | } else {
120 | return execute('netsh int ipv4 show dynamicport tcp').
121 | then(function(stdout) {
122 | /* > netsh int ipv4 show dynamicport tcp
123 | Protocol tcp Dynamic Port Range
124 | ---------------------------------
125 | Start Port : 49152
126 | Number of Ports : 16384
127 | */
128 | var range = stdout.split(/\n/).filter(function(line) {
129 | return /.*:\s*\d+/.test(line);
130 | }).map(function(line) {
131 | return Number(line.split(/:\s*/)[1]);
132 | });
133 |
134 | return {
135 | min: range[0],
136 | max: range[0] + range[1]
137 | };
138 | });
139 | }
140 | });
141 | }
142 |
143 |
144 | /**
145 | * Tests if a port is free.
146 | * @param {number} port The port to test.
147 | * @param {string=} opt_host The bound host to test the {@code port} against.
148 | * Defaults to {@code INADDR_ANY}.
149 | * @return {!webdriver.promise.Promise.<boolean>} A promise that will resolve
150 | * with whether the port is free.
151 | */
152 | function isFree(port, opt_host) {
153 | var result = promise.defer(function() {
154 | server.cancel();
155 | });
156 |
157 | var server = net.createServer().on('error', function(e) {
158 | if (e.code === 'EADDRINUSE') {
159 | result.fulfill(false);
160 | } else {
161 | result.reject(e);
162 | }
163 | });
164 |
165 | server.listen(port, opt_host, function() {
166 | server.close(function() {
167 | result.fulfill(true);
168 | });
169 | });
170 |
171 | return result.promise;
172 | }
173 |
174 |
175 | /**
176 | * @param {string=} opt_host The bound host to test the {@code port} against.
177 | * Defaults to {@code INADDR_ANY}.
178 | * @return {!webdriver.promise.Promise.<number>} A promise that will resolve
179 | * to a free port. If a port cannot be found, the promise will be
180 | * rejected.
181 | */
182 | function findFreePort(opt_host) {
183 | return findSystemPortRange().then(function(range) {
184 | var attempts = 0;
185 | var deferredPort = promise.defer();
186 | findPort();
187 | return deferredPort.promise;
188 |
189 | function findPort() {
190 | attempts += 1;
191 | if (attempts > 10) {
192 | deferredPort.reject(Error('Unable to find a free port'));
193 | }
194 |
195 | var port = Math.floor(
196 | Math.random() * (range.max - range.min) + range.min);
197 | isFree(port, opt_host).then(function(isFree) {
198 | if (isFree) {
199 | deferredPort.fulfill(port);
200 | } else {
201 | findPort();
202 | }
203 | });
204 | }
205 | });
206 | }
207 |
208 |
209 | // PUBLIC API
210 |
211 |
212 | exports.findFreePort = findFreePort;
213 | exports.isFree = isFree;