feat: return correct config for CS processors

When MC is running on a processor with a control subnet and a user
attempts to access the UI via the control subnet, the return _config.local.json
needs to reflect the CS LAN IP address for the processor rather than the LAN IP Address.

In order to accomplish this, there will now be 2 config files written to disk on startup:
1. the original file, /user/programX/mcUserApp/_local-config/_config.local.json
2. A file with the correct CS IP Address /user/programX/mcUserApp/_local-config/_config.cs.json

When a user requests the _config.local.json, the processor will compare the remote IP address
with the CS LAN IP Address and determine if they're in the same subnet, the assumption being
that if the IP Addresses are in the same subnet, then the app or end user is on the CS LAN and needs the CS config.
If the addresses are in the same subnet, then the contents of the _config.cs.json will be returned.

src/PepperDash.Essentials.Core/Extensions/IpAddressExtensions.cs

@@ -0,0 +1,86 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace PepperDash.Essentials.Core
+{
+    /// <summary>
+    /// Exnsions for IPAddress to provide additional functionality such as getting broadcast address, network address, and checking if two addresses are in the same subnet.
+    /// </summary>
+    public static class IPAddressExtensions
+    {
+        /// <summary>
+        /// Get the broadcast address for a given IP address and subnet mask.
+        /// </summary>
+        /// <param name="address">Address to check</param>
+        /// <param name="subnetMask">Subnet mask in a.b.c.d format</param>
+        /// <returns>Broadcast address</returns>
+        /// <remarks>
+        /// If the input IP address is 192.168.1.100 and the subnet mask is 255.255.255.0, the broadcast address will be 192.168.1.255
+        /// </remarks>
+        /// <exception cref="ArgumentException"></exception>
+        public static IPAddress GetBroadcastAddress(this IPAddress address, IPAddress subnetMask)
+        {
+            byte[] ipAdressBytes = address.GetAddressBytes();
+            byte[] subnetMaskBytes = subnetMask.GetAddressBytes();
+
+            if (ipAdressBytes.Length != subnetMaskBytes.Length)
+                throw new ArgumentException("Lengths of IP address and subnet mask do not match.");
+
+            byte[] broadcastAddress = new byte[ipAdressBytes.Length];
+            for (int i = 0; i < broadcastAddress.Length; i++)
+            {
+                broadcastAddress[i] = (byte)(ipAdressBytes[i] | (subnetMaskBytes[i] ^ 255));
+            }
+            return new IPAddress(broadcastAddress);
+        }
+
+        /// <summary>
+        /// Get the network address for a given IP address and subnet mask.
+        /// </summary>
+        /// <param name="address">Address to check</param>
+        /// <param name="subnetMask">Subnet mask in a.b.c.d</param>
+        /// <returns>Network Address</returns>
+        /// /// <remarks>
+        /// If the input IP address is 192.168.1.100 and the subnet mask is 255.255.255.0, the network address will be 192.168.1.0
+        /// </remarks>
+        /// <exception cref="ArgumentException"></exception>
+        public static IPAddress GetNetworkAddress(this IPAddress address, IPAddress subnetMask)
+        {
+            byte[] ipAdressBytes = address.GetAddressBytes();
+            byte[] subnetMaskBytes = subnetMask.GetAddressBytes();
+
+            if (ipAdressBytes.Length != subnetMaskBytes.Length)
+                throw new ArgumentException("Lengths of IP address and subnet mask do not match.");
+
+            byte[] broadcastAddress = new byte[ipAdressBytes.Length];
+            for (int i = 0; i < broadcastAddress.Length; i++)
+            {
+                broadcastAddress[i] = (byte)(ipAdressBytes[i] & (subnetMaskBytes[i]));
+            }
+            return new IPAddress(broadcastAddress);
+        }
+
+        /// <summary>
+        /// Determine if two IP addresses are in the same subnet.
+        /// </summary>
+        /// <param name="address2">Address to check</param>
+        /// <param name="address">Second address to check</param>
+        /// <param name="subnetMask">Subnet mask to use to compare the 2 IP Address</param>
+        /// <returns>True if addresses are in the same subnet</returns>
+        /// <remarks>
+        /// If the input IP addresses are 192.168.1.100 and 192.168.1.200, and the subnet mask is 255.255.255.0, this will return true.
+        /// If the input IP addresses are 10.1.1.100 and 192.168.1.100, and the subnet mask is 255.255.255.0, this will return false.
+        /// </remarks>
+        public static bool IsInSameSubnet(this IPAddress address2, IPAddress address, IPAddress subnetMask)
+        {
+            IPAddress network1 = address.GetNetworkAddress(subnetMask);
+            IPAddress network2 = address2.GetNetworkAddress(subnetMask);
+
+            return network1.Equals(network2);
+        }
+    }
+}

src/PepperDash.Essentials.MobileControl/WebSocketServer/UiClient.cs

@@ -0,0 +1,145 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using PepperDash.Core;
+using PepperDash.Essentials.AppServer.Messengers;
+using PepperDash.Essentials.RoomBridges;
+using Serilog.Events;
+using System;
+using System.Text.RegularExpressions;
+using WebSocketSharp;
+using WebSocketSharp.Server;
+using ErrorEventArgs = WebSocketSharp.ErrorEventArgs;
+
+
+namespace PepperDash.Essentials.WebSocketServer
+{
+    /// <summary>
+    /// Represents the behaviour to associate with a UiClient for WebSocket communication
+    /// </summary>
+    public class UiClient : WebSocketBehavior
+    {
+        public MobileControlSystemController Controller { get; set; }
+
+        public string RoomKey { get; set; }
+
+        private string _clientId;
+
+        private DateTime _connectionTime;
+
+        public TimeSpan ConnectedDuration
+        {
+            get
+            {
+                if (Context.WebSocket.IsAlive)
+                {
+                    return DateTime.Now - _connectionTime;
+                }
+                else
+                {
+                    return new TimeSpan(0);
+                }
+            }
+        }
+
+        public UiClient()
+        {
+
+        }
+
+        protected override void OnOpen()
+        {
+            base.OnOpen();
+
+            var url = Context.WebSocket.Url;
+            Debug.LogMessage(LogEventLevel.Verbose, "New WebSocket Connection from: {0}", null, url);
+
+            var match = Regex.Match(url.AbsoluteUri, "(?:ws|wss):\\/\\/.*(?:\\/mc\\/api\\/ui\\/join\\/)(.*)");
+
+            if (!match.Success)
+            {
+                _connectionTime = DateTime.Now;
+                return;
+            }
+
+            var clientId = match.Groups[1].Value;
+            _clientId = clientId;
+
+            if (Controller == null)
+            {
+                Debug.LogMessage(LogEventLevel.Verbose, "WebSocket UiClient Controller is null");
+                _connectionTime = DateTime.Now;
+            }
+
+            var clientJoinedMessage = new MobileControlMessage
+            {
+                Type = "/system/clientJoined",
+                Content = JToken.FromObject(new
+                {
+                    clientId,
+                    roomKey = RoomKey,
+                })
+            };
+
+            Controller.HandleClientMessage(JsonConvert.SerializeObject(clientJoinedMessage));
+
+            var bridge = Controller.GetRoomBridge(RoomKey);
+
+            if (bridge == null) return;
+
+            SendUserCodeToClient(bridge, clientId);
+
+            bridge.UserCodeChanged -= Bridge_UserCodeChanged;
+            bridge.UserCodeChanged += Bridge_UserCodeChanged;
+
+            // TODO: Future: Check token to see if there's already an open session using that token and reject/close the session 
+        }
+
+        private void Bridge_UserCodeChanged(object sender, EventArgs e)
+        {
+            SendUserCodeToClient((MobileControlEssentialsRoomBridge)sender, _clientId);
+        }
+
+        private void SendUserCodeToClient(MobileControlBridgeBase bridge, string clientId)
+        {
+            var content = new
+            {
+                userCode = bridge.UserCode,
+                qrUrl = bridge.QrCodeUrl,
+            };
+
+            var message = new MobileControlMessage
+            {
+                Type = "/system/userCodeChanged",
+                ClientId = clientId,
+                Content = JToken.FromObject(content)
+            };
+
+            Controller.SendMessageObjectToDirectClient(message);
+        }
+
+        protected override void OnMessage(MessageEventArgs e)
+        {
+            base.OnMessage(e);
+
+            if (e.IsText && e.Data.Length > 0 && Controller != null)
+            {
+                // Forward the message to the controller to be put on the receive queue
+                Controller.HandleClientMessage(e.Data);
+            }
+        }
+
+        protected override void OnClose(CloseEventArgs e)
+        {
+            base.OnClose(e);
+
+            Debug.LogMessage(LogEventLevel.Verbose, "WebSocket UiClient Closing: {0} reason: {1}", null, e.Code, e.Reason);
+        }
+
+        protected override void OnError(ErrorEventArgs e)
+        {
+            base.OnError(e);
+
+            Debug.LogMessage(LogEventLevel.Verbose, "WebSocket UiClient Error: {exception} message: {message}", e.Exception, e.Message);
+        }
+    }
+}