Imports System.Net
Imports System.Net.Sockets
Imports System.Threading

Public Class DateTimeServer
  Public Shared Sub Main()
    Dim serverSocket As System.Net.Sockets.Socket

    Try
      Dim hostname As String = Dns.GetHostName()
      Dim serverIP As IPAddress = Dns.Resolve(hostname).AddressList(0)

            ' DateTime Server Port = 13
            Dim Port As String = "13"
      Dim serverhost As New IPEndPoint(serverIP, Int32.Parse(Port))

      serverSocket = New Socket( _
        AddressFamily.InterNetwork, _
        SocketType.Stream, _
        ProtocolType.Tcp)

      serverSocket.Bind(serverhost)

      ' Backlog = 50
      serverSocket.Listen(50)

      Console.WriteLine("DateTime server started at: " + serverhost.Address.ToString() + ":" + Port)

      Dim lc As New ListenClient(serverSocket)
      Dim serverthread As New Thread( _
          New ThreadStart(AddressOf lc.ServerThreadProc))

      serverthread.Start()
    Catch ex As Exception
      Console.WriteLine(ex.StackTrace.ToString())
    End Try
  End Sub
End Class

Imports System.Net
Imports System.Net.Sockets
Imports System.Threading
Imports System.Text

Public Class ListenClient
  Private serverSocket As System.Net.Sockets.Socket

  ' 建構函式
  Public Sub New(ByVal serverSocket As System.Net.Sockets.Socket)
    Me.serverSocket = serverSocket
  End Sub

  Public Sub ServerThreadProc()
    Dim clientSocket As System.Net.Sockets.Socket

    Try
      While (True)
        clientSocket = serverSocket.Accept()

        Dim clientInfo As IPEndPoint = CType( _
            clientSocket.RemoteEndPoint, _
            IPEndPoint)
        Dim serverInfo As IPEndPoint = CType( _
            serverSocket.LocalEndPoint, _
            IPEndPoint)


                Dim recvbytes(1024) As Byte
                Dim i As Integer = clientSocket.Receive(recvbytes, 0, clientSocket.Available, SocketFlags.None)

                Dim datetime As String = Encoding.ASCII.GetString(recvbytes, 0, i)

                Console.WriteLine("Receive {0} bytes.", i)
                Console.WriteLine("Current server date/Time: {0}", datetime)


        clientSocket.Shutdown(SocketShutdown.Both)
        clientSocket.Close()
      End While
    Catch ex As Exception
      Console.WriteLine(ex.StackTrace.ToString())

      If clientSocket.Connected Then
        clientSocket.Close()
      End If
    End Try
  End Sub
End Class

Imports System
Imports System.IO
Imports System.Net
Imports System.Net.Sockets
Imports System.Text

Public Class DateTimeClient
  Public Shared Sub Main()
    Dim args As String() = Environment.GetCommandLineArgs()

    If (args.Length < 2) Then
      Console.WriteLine("Usage: DateTimeClient [DateTimeServer DNS/IP]")
      Exit Sub
    End If

    Dim serverHost As String = args(1)

    Dim hostadd As IPAddress = Dns.Resolve(serverHost).AddressList(0)
    Dim EPhost As New IPEndPoint(hostadd, 13)
    Dim clientSocket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)

    Try
      clientSocket.Connect(EPhost)
    Catch ex As Exception
      Console.WriteLine(ex.ToString())
    End Try

    Try

            Dim strDate As String = datetime.Now.ToShortDateString() + " " + datetime.Now.ToLongTimeString()

            Dim byteDateLine() As Byte = Encoding.ASCII.GetBytes(strDate.ToCharArray())

            clientSocket.Send(byteDateLine, byteDateLine.Length, SocketFlags.None)

            

      clientSocket.Shutdown(SocketShutdown.Both)
      clientSocket.Close()
    Catch ec As Exception
      Console.WriteLine(ec.StackTrace.ToString())
      Exit Sub
    End Try

    Console.WriteLine("Press any key to exit.")
    Console.Read()
  End Sub
End Class