Helper function added that retrieves a local IP address

src/frontends/android/src/org/strongswan/android/logic/CharonVpnService.java

@@ -17,9 +17,13 @@
 
 package org.strongswan.android.logic;
 
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
 import java.security.cert.CertificateEncodingException;
 import java.security.cert.X509Certificate;
 import java.util.ArrayList;
+import java.util.Enumeration;
 
 import org.strongswan.android.data.VpnProfile;
 import org.strongswan.android.data.VpnProfileDataSource;
@@ -399,6 +403,39 @@ public class CharonVpnService extends VpnService implements Runnable
 	 */
 	public native void deinitializeCharon();
 
+	/**
+	 * Helper function that retrieves a local IPv4 address.
+	 *
+	 * @return string representation of an IPv4 address, or null if none found
+	 */
+	private static String getLocalIPv4Address()
+	{
+		try
+		{
+			Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces();
+			while (en.hasMoreElements())
+			{
+				NetworkInterface intf = en.nextElement();
+
+				Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses();
+				while (enumIpAddr.hasMoreElements())
+				{
+					InetAddress inetAddress = enumIpAddr.nextElement();
+					if (!inetAddress.isLoopbackAddress() && inetAddress.getAddress().length == 4)
+					{
+						return inetAddress.getHostAddress().toString();
+					}
+				}
+			}
+		}
+		catch (SocketException ex)
+		{
+			ex.printStackTrace();
+			return null;
+		}
+		return null;
+	}
+
 	/*
 	 * The libraries are extracted to /data/data/org.strongswan.android/...
 	 * during installation.