Add host configuration

Needed to fix remote access

DearFTP/Configurations/Configuration.cs

@@ -2,6 +2,7 @@
 using System;
 using System.IO;
 using System.Linq;
+using System.Net;
 using System.Security.Cryptography.X509Certificates;
 using YamlDotNet.Serialization;
 
@@ -42,6 +43,16 @@ namespace DearFTP.Configurations
 
         public bool Check()
         {
+
+            if (string.IsNullOrWhiteSpace(Server.Host))
+            {
+                Console.WriteLine("Host address is missing.");
+            }
+            if (!IPAddress.TryParse(Server.Host, out var _))
+            {
+                Server.Host = Dns.GetHostEntry(Server.Host).AddressList.First().ToString();
+            }
+
             foreach (var share in Shares)
             {
                 share.Name = Path.GetFileName(share.Path);

DearFTP/Configurations/ServerConfiguration.cs

@@ -2,6 +2,7 @@
 {
     class ServerConfiguration
     {
+        public string Host { get; set; } = "127.0.0.1";
         public ushort Port { get; set; } = 21;
         public ushort ForceDataPort { get; set; } = 0;
         public ushort ImplicitFtpsPort { get; set; } = 0;

DearFTP/Connection/Commands/PassiveCommand.cs

@@ -16,7 +16,7 @@ namespace DearFTP.Connection.Commands
 
             int port = session.DataConnection.Port;
             var portBytes = BitConverter.GetBytes((ushort)port).Reverse().Select(x => x.ToString());
-            string remote = string.Join(',', session.IP.Split('.').Concat(portBytes));
+            string remote = string.Join(',', session.Configuration.Server.Host.Split('.').Concat(portBytes));
 
             stream.Send(ResponseCode.PassiveMode, $"Entering Passive Mode ({remote})");