Question

My client program gets stuck on NetworkStream.Read even though the server is reporting it’s sending the message. The client and server are running on the same computer.

Full server code (console application)

Imports System.Net.Sockets
Imports System.Text

Module Module1
    Sub Main()
        'Dim address As New System.Net.IPAddress("127.0.0.1")
        'Dim serverSocket As New TcpListener(address, 8888)
        Dim serverSocket As New TcpListener(8888)
        Dim clientSocket As TcpClient
        Dim counter As Integer

        serverSocket.Start()
        msg("Server Started")
        counter = 0
        While (True)
            counter += 1
            clientSocket = serverSocket.AcceptTcpClient()
            msg("Client No:" + Convert.ToString(counter) + " started!")
            Dim client As New handleClient
            client.startClient(clientSocket, Convert.ToString(counter))
        End While

        clientSocket.Close()
        serverSocket.Stop()
        msg("exit")
        Console.ReadLine()
    End Sub

    Sub msg(ByVal mesg As String)
        mesg.Trim()
        Console.WriteLine(" >> " + mesg)
    End Sub

    Public Class handleClient
        Dim clientSocket As TcpClient
        Dim clNo As String
        Public Sub startClient(ByVal inClientSocket As TcpClient, ByVal clineNo As String)
            Me.clientSocket = inClientSocket
            Me.clNo = clineNo
            Dim ctThread As Threading.Thread = New Threading.Thread(AddressOf doChat)
            ctThread.Start()
        End Sub
        Private Sub doChat()
            Dim requestCount As Integer
            Dim bytesFrom(10024) As Byte
            Dim dataFromClient As String
            Dim sendBytes As [Byte]()
            Dim serverResponse As String
            Dim rCount As String
            requestCount = 0

            While (True)
                Try
                    requestCount = requestCount + 1
                    Dim networkStream As NetworkStream = clientSocket.GetStream()
                    networkStream.Read(bytesFrom, 0, CInt(clientSocket.ReceiveBufferSize))
                    dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom)
                    dataFromClient =  dataFromClient.Substring(0, dataFromClient.IndexOf("$"))
                    msg("From client-" + clNo + ": " + dataFromClient)
                    rCount = Convert.ToString(requestCount)
                    serverResponse = "Server to client(" + clNo + ") " + rCount
                    sendBytes = Encoding.ASCII.GetBytes(serverResponse)
                    networkStream.Write(sendBytes, 0, sendBytes.Length)
                    networkStream.Flush()
                    msg(serverResponse)
                Catch ex As Exception
                    MsgBox(ex.ToString)
                End Try

            End While

        End Sub
    End Class

End Module

Full client code (Forms Application)

Public Class CSocketClient
    Dim clientSocket As New System.Net.Sockets.TcpClient()
    Dim serverStream As NetworkStream

    'Connect
    Public Sub init(ByVal address As String, ByVal port As Integer)
        clientSocket.Connect(address, port)
    End Sub

    'Run once
    Public Sub runOnce()
        sendMSG("Message1 from Client$")
        receiveMSG()
        sendMSG("Message2 from Client$")
        receiveMSG()
    End Sub

    'Send msg
    Public Sub sendMSG(ByVal msg As String)
        Dim serverStream As NetworkStream = clientSocket.GetStream()
        Dim outStream As Byte() = System.Text.Encoding.ASCII.GetBytes(msg)
        serverStream.Write(outStream, 0, outStream.Length)
        serverStream.Flush()
    End Sub

    'Receive msg
    Public Sub receiveMSG()
        Dim inStream(10024) As Byte
        Dim buffSize As Integer = clientSocket.ReceiveBufferSize
        MsgBox("X")
        serverStream.Read(inStream, 0, buffSize)
        MsgBox("Y")
        Dim returndata As String = System.Text.Encoding.ASCII.GetString(inStream)
        MsgBox("Data from Server : " & returndata)
    End Sub
End Class

To use the client:

Dim client As New CSocketClient
client.init("127.0.0.1", 8888)
client.runOnce()

I added MsgBox("X") and MsgBox("Y") to verify it doesn’t get past serverStream.Read. “X” pops up just fine, it never reaches Y.

Can anyone tell why this is happening?

Answer 1

Fixed it. Send and receive need to share the same NetworkStream.. silly mistake!

Public Sub runOnce()
    Dim serverStream As NetworkStream = clientSocket.GetStream()
    sendMSG("Message1 from Client$", serverStream)
    receiveMSG(serverStream)
End Sub