NatTypeTester/STUN/Utils/StunServer.cs

using System;
using System.Linq;
using System.Net;
using System.Net.Sockets;

namespace STUN.Utils
{
	public class StunServer
	{
		public string Hostname { get; set; }
		public ushort Port { get; set; }

		public StunServer()
		{
			Hostname = @"stun.syncthing.net";
			Port = 3478;
		}

		public bool Parse(string str)
		{
			var ipPort = str.Trim().Split(':', '：');
			switch (ipPort.Length)
			{
				case 0:
					return false;
				case 1:
				{
					var host = ipPort[0].Trim();
					if (Uri.CheckHostName(host) != UriHostNameType.Dns && !IPAddress.TryParse(host, out _))
					{
						return false;
					}
					Hostname = host;
					Port = 3478;
					return true;
				}
				case 2:
				{
					var host = ipPort[0].Trim();
					if (Uri.CheckHostName(host) != UriHostNameType.Dns && !IPAddress.TryParse(host, out _))
					{
						return false;
					}
					if (ushort.TryParse(ipPort[1], out var port))
					{
						Hostname = host;
						Port = port;
						return true;
					}
					break;
				}
				default:
				{
					if (IPAddress.TryParse(str.Trim(), out var ipv6))
					{
						Hostname = $@"{ipv6}";
						Port = ushort.TryParse(ipPort.Last(), out var portV6) ? portV6 : (ushort)3478;
						return true;
					}

					var ipStr = string.Join(@":", ipPort, 0, ipPort.Length - 1);
					if (!ipStr.StartsWith(@"[") || !ipStr.EndsWith(@"]") || !IPAddress.TryParse(ipStr, out _))
					{
						return false;
					}

					if (ushort.TryParse(ipPort.Last(), out var port))
					{
						Port = port;
						return true;
					}

					break;
				}
			}

			return false;
		}

		public override string ToString()
		{
			if (string.IsNullOrEmpty(Hostname))
			{
				return string.Empty;
			}
			if (Port == 3478)
			{
				return Hostname;
			}
			if (IPAddress.TryParse(Hostname, out var ip) && ip.AddressFamily != AddressFamily.InterNetwork)
			{
				return $@"[{Hostname}]:{Port}";
			}
			return $@"{Hostname}:{Port}";
		}
	}
}