/GKNetCore/NetHelper.cs

/*

 *  "GKCommunicator", the chat and bulletin board of the genealogical network.

 *  Copyright (C) 2018 by Sergey V. Zhdanovskih.

 *

 *  This file is part of "GEDKeeper".

 *

 *  This program is free software: you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation, either version 3 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



using System.Net;

using System.Net.NetworkInformation;

using System.Net.Sockets;



namespace GKNet

{

    public static class NetHelper

    {

        // Fatal problem:

        // if there is an address statically assigned to the corporate network,

        // then there is still no correct external address

        private static IPAddress GetPublicAddress()

        {

            NetworkInterface[] networkInterfaces = NetworkInterface.GetAllNetworkInterfaces();



            // weed out addresses of virtual adapters (VirtualBox, VMWare, Tunngle, etc.)

            foreach (NetworkInterface network in networkInterfaces) {

                IPInterfaceProperties properties = network.GetIPProperties();

                if (properties.GatewayAddresses.Count == 0) {

                    // all the magic is in this line

                    continue;

                }



                foreach (IPAddressInformation address in properties.UnicastAddresses) {

                    if (address.Address.AddressFamily != AddressFamily.InterNetwork)

                        continue;



                    if (IPAddress.IsLoopback(address.Address))

                        continue;



                    return address.Address;

                }

            }



            return default(IPAddress);

        }



        public static string GetPublicIPAddress()

        {

            if (!NetworkInterface.GetIsNetworkAvailable()) {

                return null;

            }



            try {

                string externalIP = GetPublicAddress().ToString();

                /*externalIP = (new WebClient()).DownloadString("http://checkip.dyndns.org/");

                externalIP = (new Regex(@"\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}"))

                             .Matches(externalIP)[0].ToString();*/

                return externalIP;

            } catch { return null; }

        }



#if NET35

        // IPv4 192.168.1.1 maps as ::FFFF:192.168.1.1

        public static IPAddress MapToIPv6(this IPAddress address)

        {

            if (address.AddressFamily == AddressFamily.InterNetworkV6) {

                return address;

            }



            byte[] addr = address.GetAddressBytes();

            byte[] labels = new byte[16];

            labels[10] = 0xFF;

            labels[11] = 0xFF;

            labels[12] = addr[0];

            labels[13] = addr[1];

            labels[14] = addr[2];

            labels[15] = addr[3];

            return new IPAddress(labels, 0);

        }

#endif

    }

}