NatTypeTester/STUN/Utils/NetUtils.cs

using STUN.Client;
using STUN.StunResult;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Threading.Tasks;

namespace STUN.Utils
{
    public static class NetUtils
    {
        public const string DefaultLocalEnd = @"0.0.0.0:0";

        public static IPEndPoint ParseEndpoint(string str)
        {
            var ipPort = str.Trim().Split(':');
            if (ipPort.Length < 2) return null;
            IPAddress ip = null;
            if (ipPort.Length == 2 && IPAddress.TryParse(ipPort[0], out ip))
            {
                if (!IPAddress.TryParse(ipPort[0], out ip))
                {
                    return null;
                }
            }
            else if (ipPort.Length > 2)
            {
                var ipStr = string.Join(@":", ipPort, 0, ipPort.Length - 1);
                if (!ipStr.StartsWith(@"[") || !ipStr.EndsWith(@"]") || !IPAddress.TryParse(ipStr, out ip))
                {
                    return null;
                }
            }

            if (ip != null && ushort.TryParse(ipPort.Last(), out var port))
            {
                return new IPEndPoint(ip, port);
            }

            return null;
        }

        public static async Task<StunResult5389> NatBehaviorDiscovery(string server, ushort port, IPEndPoint local)
        {
            // proxy is not supported yet
            using var client = new StunClient5389UDP(server, port, local);
            return await client.QueryAsync();
        }

        public static TcpState GetState(this TcpClient tcpClient)
        {
            var foo = IPGlobalProperties.GetIPGlobalProperties()
              .GetActiveTcpConnections()
              .SingleOrDefault(x => x.LocalEndPoint.Equals(tcpClient.Client.LocalEndPoint));
            return foo?.State ?? TcpState.Unknown;
        }
    }
}