Merge pull request #50 from da66en/feature_server_specify_ip

Specify network interface for TCP and UDP servers

Author: rossmann-engineering

EasyModbus/ModbusServer.cs

@@ -85,27 +85,40 @@ internal class TCPHandler
         public event NumberOfClientsChanged numberOfClientsChanged;
 
         TcpListener server = null;
-        
+
 
         private List<Client> tcpClientLastRequestList = new List<Client>();
 
         public int NumberOfConnectedClients { get; set; }
 
         public string ipAddress = null;
 
+        /// When making a server TCP listen socket, will listen to this IP address.
+        public IPAddress LocalIPAddress {
+            get { return localIPAddress; }
+        }
+        private IPAddress localIPAddress = IPAddress.Any;
+
+        /// <summary>
+        /// Listen to all network interfaces.
+        /// </summary>
+        /// <param name="port">TCP port to listen</param>
         public TCPHandler(int port)
         {
-            IPAddress localAddr = IPAddress.Any;
-            server = new TcpListener(localAddr, port);
+            server = new TcpListener(LocalIPAddress, port);
             server.Start();
             server.BeginAcceptTcpClient(AcceptTcpClientCallback, null);
         }
 
-        public TCPHandler(string ipAddress, int port)
+        /// <summary>
+        /// Listen to a specific network interface.
+        /// </summary>
+        /// <param name="localIPAddress">IP address of network interface to listen</param>
+        /// <param name="port">TCP port to listen</param>
+        public TCPHandler(IPAddress localIPAddress, int port)
         {
-            this.ipAddress = ipAddress;
-            IPAddress localAddr = IPAddress.Any;
-            server = new TcpListener(localAddr, port);
+            this.localIPAddress = localIPAddress;
+            server = new TcpListener(LocalIPAddress, port);
             server.Start();
             server.BeginAcceptTcpClient(AcceptTcpClientCallback, null);
         }
@@ -311,8 +324,17 @@ public class ModbusServer
         object lockCoils = new object();
         object lockHoldingRegisters = new object();
         private volatile bool shouldStop;
-        
 
+        private IPAddress localIPAddress = IPAddress.Any;
+
+        /// <summary>
+        /// When creating a TCP or UDP socket, the local IP address to attach to.
+        /// </summary>
+        public IPAddress LocalIPAddress
+        {
+            get { return localIPAddress; }
+            set { if (listenerThread == null) localIPAddress = value; }
+        }
 
         public ModbusServer()
         {
@@ -379,9 +401,9 @@ private void ListenerThread()
                         udpClient.Close();
                     }
                     catch (Exception) { }
-                }             
-                tcpHandler = new TCPHandler(port);
-                if (debug) StoreLogData.Instance.Store("EasyModbus Server listing for incomming data at Port " + port, System.DateTime.Now);
+                }
+                tcpHandler = new TCPHandler(LocalIPAddress, port);
+                if (debug) StoreLogData.Instance.Store($"EasyModbus Server listing for incomming data at Port {port}, local IP {LocalIPAddress}", System.DateTime.Now);
                 tcpHandler.dataChanged += new TCPHandler.DataChanged(ProcessReceivedData);
                 tcpHandler.numberOfClientsChanged += new TCPHandler.NumberOfClientsChanged(numberOfClientsChanged);
             }
@@ -408,8 +430,9 @@ private void ListenerThread()
             	{
                     if (udpClient == null | PortChanged)
                     {
-                        udpClient = new UdpClient(port);
-                        if (debug) StoreLogData.Instance.Store("EasyModbus Server listing for incomming data at Port " + port, System.DateTime.Now);
+                        IPEndPoint localEndoint = new IPEndPoint(LocalIPAddress, port);
+                        udpClient = new UdpClient(localEndoint);
+                        if (debug) StoreLogData.Instance.Store($"EasyModbus Server listing for incomming data at Port {port}, local IP {LocalIPAddress}", System.DateTime.Now);
                         udpClient.Client.ReceiveTimeout = 1000;
                         iPEndPoint = new IPEndPoint(IPAddress.Any, port);
                         PortChanged = false;