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Utilities for use within Java projects
/*
* Copyright 2015 dorkbox, llc
*
* 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.
*/
package dorkbox.util;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.*;
import java.util.Enumeration;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public final
class NetworkUtil {
/**
* Returns an InetAddress object encapsulating what is most likely the machine's LAN IP address.
*
* This method is intended for use as a replacement of JDK method InetAddress.getLocalHost, because
* that method is ambiguous on Linux systems. Linux systems enumerate the loopback network interface the same
* way as regular LAN network interfaces, but the JDK InetAddress.getLocalHost method does not
* specify the algorithm used to select the address returned under such circumstances, and will often return the
* loopback address, which is not valid for network communication. Details
* here.
*
* This method will scan all IP addresses on all network interfaces on the host machine to determine the IP address
* most likely to be the machine's LAN address. If the machine has multiple IP addresses, this method will prefer
* a site-local IP address (e.g. 192.168.x.x or 10.10.x.x, usually IPv4) if the machine has one (and will return the
* first site-local address if the machine has more than one), but if the machine does not hold a site-local
* address, this method will return simply the first non-loopback address found (IPv4 or IPv6).
*
* If this method cannot find a non-loopback address using this selection algorithm, it will fall back to
* calling and returning the result of JDK method InetAddress.getLocalHost.
*
*
* @throws UnknownHostException If the LAN address of the machine cannot be found.
*
* From: https://issues.apache.org/jira/browse/JCS-40
*/
public static
InetAddress getLocalHost() throws UnknownHostException {
try {
InetAddress candidateAddress = null;
// Iterate all NICs (network interface cards)...
for (Enumeration ifaces = NetworkInterface.getNetworkInterfaces(); ifaces.hasMoreElements(); ) {
NetworkInterface iface = ifaces.nextElement();
// Iterate all IP addresses assigned to each card...
for (Enumeration inetAddrs = iface.getInetAddresses(); inetAddrs.hasMoreElements(); ) {
InetAddress inetAddr = inetAddrs.nextElement();
if (!inetAddr.isLoopbackAddress()) {
if (inetAddr.isSiteLocalAddress()) {
// Found non-loopback site-local address. Return it immediately...
return inetAddr;
}
else if (candidateAddress == null) {
// Found non-loopback address, but not necessarily site-local.
// Store it as a candidate to be returned if site-local address is not subsequently found...
candidateAddress = inetAddr;
// Note that we don't repeatedly assign non-loopback non-site-local addresses as candidates,
// only the first. For subsequent iterations, candidate will be non-null.
}
}
}
}
if (candidateAddress != null) {
// We did not find a site-local address, but we found some other non-loopback address.
// Server might have a non-site-local address assigned to its NIC (or it might be running
// IPv6 which deprecates the "site-local" concept).
// Return this non-loopback candidate address...
return candidateAddress;
}
// At this point, we did not find a non-loopback address.
// Fall back to returning whatever InetAddress.getLocalHost() returns...
InetAddress jdkSuppliedAddress = InetAddress.getLocalHost();
if (jdkSuppliedAddress == null) {
throw new UnknownHostException("The JDK InetAddress.getLocalHost() method unexpectedly returned null.");
}
return jdkSuppliedAddress;
} catch (Exception e) {
UnknownHostException unknownHostException = new UnknownHostException("Failed to determine LAN address: " + e);
unknownHostException.initCause(e);
throw unknownHostException;
}
}
/**
* This will retrieve your IP address via an HTTP server.
*
* NOTE: Use DnsClient.getPublicIp() instead. It's much faster and more reliable as it uses DNS.
*
* @return the public IP address if found, or null if it didn't find it
*/
@Deprecated
public static
String getPublicIpViaHttp() {
// method 1: use DNS servers
// dig +short myip.opendns.com @resolver1.opendns.com
// method 2: use public http servers
// @formatter:off
final String websites[] = {"http://ip.dorkbox.com/",
"http://ip.javalauncher.com/",
"http://checkip.dyndns.com/",
"http://checkip.dyn.com/",
"http://curlmyip.com/",
"http://tnx.nl/ip",
"http://ipecho.net/plain",
"http://icanhazip.com/",
"http://ip.appspot.com/",};
// @formatter:on
// loop, since they won't always work.
for (int i = 0; i < websites.length; i++) {
try {
URL autoIP = new URL(websites[i]);
BufferedReader in = new BufferedReader(new InputStreamReader(autoIP.openStream()));
String response = in.readLine()
.trim();
in.close();
Pattern pattern = Pattern.compile("\\b\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\b");
Matcher matcher = pattern.matcher(response);
if (matcher.find()) {
return matcher.group()
.trim();
}
} catch (Exception ignored) {
}
}
return null;
}
/**
* Tries to retrieve the IP address from the NIC. Order is ETHx -> EMx -> WLANx
*
* @return null if not found
*/
public static
InetAddress getIpAddressesFromNic() {
try {
Enumeration nets = NetworkInterface.getNetworkInterfaces();
while (nets.hasMoreElements()) {
NetworkInterface nextElement = nets.nextElement();
String name = nextElement.getName();
// we only want to use ethX addresses!
if (name.startsWith("eth")) {
Enumeration inetAddresses = nextElement.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
InetAddress address = inetAddresses.nextElement();
// we only support IPV4 addresses.
if (!address.isLoopbackAddress() && address instanceof Inet4Address) {
return address;
}
}
}
}
// it didn't work with ethX, so try emX!
while (nets.hasMoreElements()) {
nets = NetworkInterface.getNetworkInterfaces();
NetworkInterface nextElement = nets.nextElement();
String name = nextElement.getName();
// we only want to use emX addresses!
if (name.startsWith("em")) {
Enumeration inetAddresses = nextElement.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
InetAddress address = inetAddresses.nextElement();
// we only support IPV4 addresses.
if (!address.isLoopbackAddress() && address instanceof Inet4Address) {
return address;
}
}
}
}
// it didn't work with emX, so try enX!
while (nets.hasMoreElements()) {
nets = NetworkInterface.getNetworkInterfaces();
NetworkInterface nextElement = nets.nextElement();
String name = nextElement.getName();
// we only want to use enX addresses!
if (name.startsWith("en")) {
Enumeration inetAddresses = nextElement.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
InetAddress address = inetAddresses.nextElement();
// we only support IPV4 addresses.
if (!address.isLoopbackAddress() && address instanceof Inet4Address) {
return address;
}
}
}
}
// it didn't work with ethX, so try wifi!
while (nets.hasMoreElements()) {
nets = NetworkInterface.getNetworkInterfaces();
NetworkInterface nextElement = nets.nextElement();
String name = nextElement.getName();
// we only want to use wlanX addresses!
if (name.startsWith("wlan")) {
Enumeration inetAddresses = nextElement.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
InetAddress address = inetAddresses.nextElement();
// we only support IPV4 addresses.
if (!address.isLoopbackAddress() && address instanceof Inet4Address) {
return address;
}
}
}
}
} catch (SocketException ignored) {
}
return null;
}
/**
* @return the String representation of the given IPv4 address
*/
public static
String ipv4ToString(byte[] address) {
return (address[0] & 0xFF) + "." + (address[1] & 0xFF) + "." + (address[2] & 0xFF) + "." + (address[3] & 0xFF);
}
private
NetworkUtil() {
}
}
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