A random but realistic IP address generator. It makes use of country specific CIDR address files read from the resource directory. Files can be downloaded from http://www.ip2location.com/free/visitor-blocker in the CIDR format (each line is similar to 222.165.0.0/17). For the purpose of testing, a few CIDR addresses have been selected for a few …

IPAddressGenerator

package net.nirmalya.util.ipaddr;

import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.Scanner;

import org.apache.commons.net.util.SubnetUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Generates IP addresses based on randomly selected address block(s) read from country specific file(s) in the resource
 * directory.
 * 
 * @author Nirmalya Ghosh
 */
public class IPAddressGenerator {

	private final boolean useSampleFile = true;
	private static final IPAddressGenerator INSTANCE = new IPAddressGenerator();
	private static Logger logger = LoggerFactory.getLogger(IPAddressGenerator.class);
	private Map<Integer, String> lines = new HashMap<Integer, String>();
	private Random random = new Random();
	private String countryCodeLoaded;

	public static String generateIPAddress(Country countryCode) {
		return INSTANCE.generate(countryCode);
	}

	public static String[] generateIPAddresses(Country countryCode, int count) {
		String[] ipAddresses = new String[count];
		for (int i = 0; i < count; i++) {
			ipAddresses[i] = INSTANCE.generate(countryCode);
		}
		return ipAddresses;
	}

	public static void main(String[] args) {
		IPAddressGenerator.generateIPAddress(Country.SINGAPORE);
	}

	private IPAddressGenerator() {
	}

	private String generate(Country countryCode) {
		loadCidrFile(countryCode);
		int lineNumber = 1 + this.random.nextInt(this.lines.size());
		String cidr = this.lines.get(lineNumber).trim();
		while (cidr.endsWith("/31") || cidr.endsWith("/32")) {
			// TODO figure out why exceptions are thrown when /31 and /32
			cidr = this.lines.get(this.random.nextInt(this.lines.size()));
		}

		SubnetUtils util = new SubnetUtils(cidr);
		String[] ipAddresses = util.getInfo().getAllAddresses();
		int index = this.random.nextInt(ipAddresses.length);
		String ipAddress = ipAddresses[index];
		logger.debug("Selected {} (#{} of {} IP addresses based on {})", ipAddress, index, ipAddresses.length, cidr);
		return ipAddress;
	}

	private void loadCidrFile(Country country) {
		if ((this.countryCodeLoaded != null) && (this.countryCodeLoaded.equals(country.getCode()))) {
			return;
		}

		this.lines.clear();
		String cidrFileName = String.format((useSampleFile ? "sample-" : "") + "cidr-%s.txt", country.getCode());
		InputStream inputStream = IPAddressGenerator.class.getResourceAsStream(cidrFileName);
		int lineNumber = 0;
		try (Scanner scanner = new Scanner(inputStream)) {
			while (scanner.hasNextLine()) {
				this.lines.put(++lineNumber, scanner.nextLine());
			}
			this.countryCodeLoaded = country.getCode();
			logger.debug("{} lines read from {}", this.lines.size(), cidrFileName);
		} catch (Exception e) {
			logger.debug("Caught an exception whilst reading {} {}", cidrFileName, e);
		}
	}
}


/**
 * Represents the country codes. Used to refer to specific configuration files.
 * 
 * @author Nirmalya Ghosh
 */
public enum Country {
	AUSTRALIA("AU"), 
	CHINA("CN"), 
	INDIA("IN"), 
	SINGAPORE("SG");

	private String code;

	private Country(String countryCode) {
		this.code = countryCode;
	}

	public String getCode() {
		return code;
	}
}

sample-cidr-AU.txt

37.139.65.0/24
59.167.87.0/24
101.160.198.0/24
163.232.0.0/15
210.193.128.0/17

sample-cidr-CN.txt

112.64.0.0/14
180.208.0.0/15
202.152.176.0/20
203.12.130.0/24
210.31.0.0/17

sample-cidr-IN.txt

14.139.0.0/16
27.56.0.0/13
59.145.0.0/17
59.164.0.0/15
61.246.57.0/24
112.110.0.0/16
113.19.0.0/16
114.143.186.0/24
116.119.0.0/16
121.242.0.0/16
122.160.0.0/12
125.20.0.0/24
171.48.0.0/12
202.144.0.0/17
202.157.64.0/24
203.88.128.0/19
220.156.184.0/21
223.224.0.0/12

sample-cidr-SG.txt

218.186.0.0/16
219.74.0.0/16
220.255.0.0/16
221.128.0.0/18
222.165.0.0/17