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


Public Class tcmlistenersample
    Shared Sub usage()
        Console.WriteLine(" Uso: TcpListnerSampleVB-")
        Console.WriteLine()
        Console.WriteLine(" Available options-")
        Console.WriteLine(" -l address      Local address for TCP server to listen on-")
        Console.WriteLine(" -p port         Local port for TCP server to listen on-")
        Console.WriteLine(" -x size         Size of send and receive buffers-")
        Console.WriteLine()
    End Sub

    Shared Sub Main()
        Dim listenInterface As IPAddress = IPAddress.Any
        Dim listenPort As Short = 10005
        Dim bufferSize As Integer = 4096
        Dim a As Integer
        Dim args As String() = Environment.GetCommandLineArgs()
        'usage()
        For a = 1 To args.GetUpperBound(0) - 1
            Try
                Dim CurArg() As Char = args(a).ToCharArray(0, args(a).Length)
                If (CurArg(0) = "-") Or (CurArg(0) = "/") Then
                    Select Case Char.ToLower(CurArg(1), System.Globalization.CultureInfo.CurrentCulture)
                        Case "|" ' l'interfaccia locale del server e in ascolto
                            a = a + 1
                            listenInterface = IPAddress.Parse(args(a))
                        Case "p" 'numero della porta per la destinazione
                            a = a + 1
                            listenPort = System.Convert.ToInt16(args(a))
                        Case "x" ' grandezza dell'invio e ricezione del buffer
                            a = a + 1
                            bufferSize = System.Convert.ToInt32(args(a))
                        Case Else
                            usage()
                            Exit Sub
                    End Select
                End If
            Catch ex As Exception
                usage()
                Exit Sub
            End Try
        Next

        Dim tcpServer As TcpListener = Nothing
        Dim tcpclient As TcpClient = Nothing
        Dim tcpstream As NetworkStream = Nothing
        Dim sendbuffer(bufferSize) As Byte
        Dim receiveBuffer(bufferSize) As Byte
        Dim byteCount() As Byte
        Dim byteToRead As Integer = 0
        Dim nextReadCount, rc As Integer

        'inizializzazione dell'invio del buffer

        Console.WriteLine("inizializzazione del buffer ...")
        For a = 0 To sendbuffer.Length - 1
            sendbuffer(a) = CByte(65)
        Next
        Try
            'creazione del tcp server 
            Console.WriteLine("TCP creato sull'indirizzo {0} e sulla porta numero{1}", listenInterface.ToString(), listenPort.ToString)
            'Inizio ascolto della connessione
            Console.WriteLine("Avviato l'ascolto sulla connessione")
            tcpServer = New TcpListener(listenInterface, listenPort)
            tcpServer.Start()
            'attende la connessione con il client
            Console.WriteLine("in attesa della connessionecon il client")
            tcpclient = tcpServer.AcceptTcpClient()
            'Prendi il NetworkStream in modo che possiamo fare di lettura e scrittura sul client di connessione
            Console.WriteLine("Ottenere il NetworkStream per leggere e scrivere nel client di connessione")
            tcpstream = tcpclient.GetStream()
            byteCount = BitConverter.GetBytes(byteToRead)
            'Prima di leggere il numero di byte il client invia
            Console.WriteLine("La lettura del numero di byte il client invia...")
            tcpstream.Read(byteCount, 0, byteCount.Length)
            byteToRead = BitConverter.ToInt32(byteCount, 0)
            'riceve i dati
            Console.WriteLine("Receive, Read & display data...")
            While (byteToRead > 0)
                If (byteToRead < receiveBuffer.Length) Then
                    nextReadCount = byteToRead
                Else
                    nextReadCount = receiveBuffer.Length
                End If
                ' Read some data
                rc = tcpstream.Read(receiveBuffer, 0, nextReadCount)
                ' Display what we read
                Dim readText As String = System.Text.Encoding.ASCII.GetString(receiveBuffer, 0, rc)
                Console.WriteLine("Received: {0}", readText)
                byteToRead -= rc
            End While
            Console.WriteLine("invi i numero di byte del server e responde con .... ")
            byteCount = BitConverter.GetBytes(sendbuffer.Length)
            tcpstream.Write(byteCount, 0, sendbuffer.Length)

            Console.WriteLine("Chiusura sul client")
            tcpstream.Close()
            tcpstream = Nothing

            tcpclient.Close()
            tcpclient = Nothing
        Catch ex As Exception
            ' Exceptions on the TcpListener are caught here
            Console.WriteLine("Socket error occurred: {0}", Err.Description)
            '' Catch err As System.IO.IOException
            ' Exceptions on the NetworkStream are caught here
            '  Console.WriteLine("I/O error: {0}", Err.Message)
        Finally
            ' Close any remaining open resources
            Console.WriteLine("Closing any remaining open resources...")
            If (Not IsNothing(tcpServer)) Then
                tcpServer.Stop()
            End If
            If (Not IsNothing(tcpstream)) Then
                tcpstream.Close()
            End If
            If (Not IsNothing(tcpclient)) Then
                tcpclient.Close()
            End If
        End Try
    End Sub
End Class