NetworkInfo.java

package io.evercam.network.discovery;

import io.evercam.network.Constants;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.InterfaceAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.StringTokenizer;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.CoreConnectionPNames;
import org.apache.http.util.EntityUtils;

public class NetworkInfo {

    public static ArrayList<String> getNetworkInterfaceNames() {
	Enumeration<NetworkInterface> networkInterfaces = null;
	ArrayList<String> interfaceNameArrayList = new ArrayList<String>();
	try {
	    networkInterfaces = NetworkInterface.getNetworkInterfaces();
	    for (Enumeration<NetworkInterface> networkInterfaceEnum = networkInterfaces; networkInterfaces
		    .hasMoreElements();) {
		NetworkInterface networkInterface = networkInterfaceEnum
			.nextElement();
		for (Enumeration<InetAddress> nis = networkInterface
			.getInetAddresses(); nis.hasMoreElements();) {
		    InetAddress thisInetAddress = nis.nextElement();
		    if (!thisInetAddress.isLoopbackAddress()) {
			if (thisInetAddress instanceof Inet6Address) {
			    continue;
			} else {
			    interfaceNameArrayList.add(networkInterface
				    .getName());
			}
		    }
		}
	    }
	} catch (SocketException e) {
	    if (Constants.ENABLE_LOGGING) {
		e.printStackTrace();
	    }
	}
	return interfaceNameArrayList;
    }

    /**
     * Return network interface by interface name. Return null if no interface
     * matches the given name.
     */
    public static NetworkInterface getNetworkInterfaceByName(
	    String interfaceName) {
	Enumeration<NetworkInterface> networkInterfaces = null;
	try {
	    networkInterfaces = NetworkInterface.getNetworkInterfaces();
	    for (Enumeration<NetworkInterface> networkInterfaceEnum = networkInterfaces; networkInterfaces
		    .hasMoreElements();) {
		NetworkInterface networkInterface = networkInterfaceEnum
			.nextElement();
		for (Enumeration<InetAddress> nis = networkInterface
			.getInetAddresses(); nis.hasMoreElements();) {
		    InetAddress thisInetAddress = nis.nextElement();
		    if (!thisInetAddress.isLoopbackAddress()) {
			if (thisInetAddress instanceof Inet6Address) {
			    continue;
			} else {
			    if (networkInterface.getName()
				    .equals(interfaceName)) {
				return networkInterface;
			    }
			}
		    }
		}
	    }
	} catch (SocketException e) {
	    if (Constants.ENABLE_LOGGING) {
		e.printStackTrace();
	    }
	}
	return null;
    }

    /**
     * Return network interface by host IP address. Return null if no interface
     * matches the given IP
     */
    public static NetworkInterface getNetworkInterfaceByIp(String ipAddress) {
	Enumeration<NetworkInterface> networkInterfaces = null;
	try {
	    networkInterfaces = NetworkInterface.getNetworkInterfaces();
	    for (Enumeration<NetworkInterface> networkInterfaceEnum = networkInterfaces; networkInterfaces
		    .hasMoreElements();) {
		NetworkInterface networkInterface = networkInterfaceEnum
			.nextElement();
		for (Enumeration<InetAddress> nis = networkInterface
			.getInetAddresses(); nis.hasMoreElements();) {
		    InetAddress thisInetAddress = nis.nextElement();
		    if (!thisInetAddress.isLoopbackAddress()) {
			if (thisInetAddress instanceof Inet6Address) {
			    continue;
			} else {
			    if (thisInetAddress.getHostAddress().equals(
				    ipAddress)) {
				return networkInterface;
			    }
			}
		    }
		}
	    }
	} catch (SocketException e) {
	    if (Constants.ENABLE_LOGGING) {
		e.printStackTrace();
	    }
	}
	return null;
    }

    /**
     * Return the network prefix length. Return 0 if no CIDR detected. FIXME:
     * This method may return -1, which means it may not be the right approach
     */
    public static int getCidrFromInterface(NetworkInterface networkInterface)
	    throws IOException {
	for (InterfaceAddress address : networkInterface
		.getInterfaceAddresses()) {
	    InetAddress inetAddress = address.getAddress();
	    if (!inetAddress.isLoopbackAddress()) {
		if (inetAddress instanceof Inet4Address) {
		    return address.getNetworkPrefixLength();
		}
	    }
	}
	return 0;
    }

    /**
     * Return the valid ipv4 address for the given network interface. Return
     * empty string if IP address available.
     */
    public static String getIpFromInterface(NetworkInterface networkInterface)
	    throws IOException {
	for (InterfaceAddress address : networkInterface
		.getInterfaceAddresses()) {
	    InetAddress inetAddress = address.getAddress();
	    if (!inetAddress.isLoopbackAddress()) {
		if (inetAddress instanceof Inet4Address) {
		    return inetAddress.getHostAddress();
		}
	    }
	}
	return "";
    }

    public static String getExternalIP() {
	String extIP = "";
	HttpClient httpclient = new DefaultHttpClient();
	httpclient.getParams().setIntParameter(CoreConnectionPNames.SO_TIMEOUT,
		2000);
	httpclient.getParams().setIntParameter(
		CoreConnectionPNames.CONNECTION_TIMEOUT, 2000);
	try {
	    HttpGet httpget = new HttpGet(Constants.URL_GET_EXTERNAL_ADDR);
	    HttpResponse response;
	    response = httpclient.execute(httpget);
	    HttpEntity entity = response.getEntity();
	    if (entity != null) {
		extIP = EntityUtils.toString(entity);
	    }
	} catch (IOException e) {
	    if (Constants.ENABLE_LOGGING) {
		e.printStackTrace();
	    }
	} finally {
	    httpclient.getConnectionManager().shutdown();
	}
	return (extIP == "" ? "" : extIP.replace("\n", ""));
    }

    /**
     * Run command 'netstat -rn' and abstract router IP
     * 
     * Example of Kernel IP routing table Destination Gateway Genmask Flags MSS
     * Window irtt Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0 192.168.1.0
     * 0.0.0.0 255.255.255.0 U 0 0 0 eth0
     * 
     * Return router IP in Linux system. Return empty string if exception
     * occurred.
     */
    // FIXME: netstat -rn doesn't work when Internet is not connected
    public static String getLinuxRouterIp() {
	try {
	    Process result = Runtime.getRuntime().exec("netstat -rn");

	    BufferedReader output = new BufferedReader(new InputStreamReader(
		    result.getInputStream()));

	    String line = output.readLine();
	    while (line != null) {
		if (line.startsWith("0.0.0.0")) {
		    break;
		}
		line = output.readLine();
	    }

	    StringTokenizer st = new StringTokenizer(line);
	    st.nextToken();
	    return st.nextToken();
	} catch (Exception e) {
	    if (Constants.ENABLE_LOGGING) {
		e.printStackTrace();
	    }
	    return "";
	}
    }

    /**
     * Run command 'netstat -rn' and abstract subnet mask
     * 
     * Example of Kernel IP routing table Destination Gateway Genmask Flags MSS
     * Window irtt Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0 192.168.1.0
     * 0.0.0.0 255.255.255.0 U 0 0 0 eth0
     * 
     * Return subnet mask in Linux system. Return empty string if exception
     * occurred.
     */
    public static String getLinuxSubnetMask() {
	try {
	    Process result = Runtime.getRuntime().exec("netstat -rn");

	    BufferedReader output = new BufferedReader(new InputStreamReader(
		    result.getInputStream()));

	    String line = output.readLine();
	    while (line != null) {
		StringTokenizer st = new StringTokenizer(line);
		st.nextToken();
		String gateway = st.nextToken();
		if (gateway.equals("0.0.0.0")) {
		    return st.nextToken();
		}
		line = output.readLine();
	    }
	} catch (Exception e) {
	    if (Constants.ENABLE_LOGGING) {
		e.printStackTrace();
	    }
	}
	return "";
    }
}