Winsock and File Transfers

[dglienna]

Most routers are open to the normal protocols

[Murjax]

Ok well I've tested this a few different ways but haven't gotten anywhere. I don't think it's the router though because I turned off its firewall (and the computer's again) to test this. I also tested it on different computers both inside and outside the router with the same result. To me it seems like VB is purposely rejecting it. Is it possible for that to occur?

[DataMiser]

Show some of your code and maybe someone can help. At the moment you are not giving us much to go on. If you could show the part of your client code that attempts the connection and the part of your server code that accepts the connection then we might have an idea of how to direct you. As is for all we know your code is not accepting the connection.

[Murjax]

I thought I should have posted this earlier. Alright here's the code.

First the client side.

    Private Sub transferButton_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles transferButton.Click

        Const BYTE_SIZE As Integer = 1
        Dim stream As NetworkStream
        Dim fileToSend As String = fileToSendTextBox.Text
        Dim saveAs As String = saveAsTextBox.Text
        Dim IPAddress As String = "24.129.26.34"
        Dim filestream As System.IO.FileStream = Nothing
        Dim buffer(BYTE_SIZE - 1) As Byte
        Dim bytesRead As Integer = 0
        Dim port As Int32 = 13000
        Dim client As New TcpClient

        client.Connect(IPAddress, port)

        If fileToSend = "" Then
            MsgBox("You must choose a file", MsgBoxStyle.Critical, "Error")
        End If

        stream = client.GetStream()

        filestream = New System.IO.FileStream(fileToSend, _
            IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)

        Try
            Do

                bytesRead = filestream.Read(buffer, 0, BYTE_SIZE)

                If (bytesRead > 0) Then
                    stream.Write(buffer, 0, BYTE_SIZE)
                End If
            Loop While bytesRead > 0

        Catch ex As Exception
            MsgBox("ERROR", MsgBoxStyle.Critical, "ERROR")
            Me.Hide()
        End Try

    End Sub

And now the server

    Private Sub Form1_Load(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles Me.Load
        Dim stream As NetworkStream
        Dim server As TcpListener
        Dim port As Int32 = 80
        Dim IP As IPAddress = IPAddress.Parse("127.0.0.1")


        server = New TcpListener(IP, port)

        server.Start()

        While True
            Dim i As Int32
            Dim client As TcpClient = server.AcceptTcpClient()
            stream = client.GetStream()


            i = stream.Read(bytes, 0, bytes.Length)
            While (i <> 0)
                Write()
                i = stream.Read(bytes, 0, bytes.Length)
            End While
            client.Close()
        End While

[DataMiser]

Your server side code looks rather odd.

Here are some snippets from my server code.

In my server start routine I have

SocketHandler = New TcpListener(hIPAddress, hPort)  ' Set the IP AND Port Number
SocketHandler.Start()

I have a timer running which checks to see if there are any pending connections every 100ms.

If SocketHandler.Pending() Then
            CurThreadStart = New ThreadStart(AddressOf ConnectionBegin)     ' Set info for the new thread
            CurThread = New Thread(CurThreadStart)                          ' Initialize the new thread variable
            CurThread.SetApartmentState(ApartmentState.STA)
            CurThread.Start()                                               ' Start the thread
            SyncLock CurThread                                              ' Lock the thread for update
                VAActiveThreads += 1                                        ' increment active threads
                cInfo.ActiveClients += 1
                CurThread.Name = "ClientCon" + VAActiveThreads.ToString        ' Name the thread
                Console.WriteLine(CurThread.Name & " Thread Started")
            End SyncLock
End If

Then in my ConnectionBegin which is launched by the code above in a new thread I have.

Dim ClientSocket As Socket = SocketHandler.AcceptSocket

Followed by a loop that will read from the port until there is a idle timeout condition.

[Murjax]

    Private Sub Form1_Load(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles Me.Load

        server = New TcpListener(IP, port)

        server.Start()

        
    End Sub

    Private Sub FTTimer_Tick(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles FTTimer.Tick

        If server.Pending() Then
            threadStart = New ThreadStart(AddressOf ConnectionBegin)
            thread = New Thread(threadStart)
            thread.SetApartmentState(ApartmentState.STA)
            thread.Start()
        End If
    End Sub

    Private Sub ConnectionBegin()
        While True
            Dim i As Int32
            Dim client As TcpClient = server.AcceptTcpClient()
            stream = client.GetStream()


            i = stream.Read(bytes, 0, bytes.Length)
            While (i <> 0)
                Write()
                i = stream.Read(bytes, 0, bytes.Length)
            End While
            client.Close()
        End While
    End Sub

Is this slightly better? Even with the addition of a pending check, the listener still can't seem to "hear" that remote connection.

[DataMiser]

What's with the while true loop? You need to ditch that.

[DataMiser]

Duh... I just reviewed your code posted earlier and I see a problem with your port assignments.

Your server is listening on port 80 but your client is trying to connect on port 13000.

You must use the port that the listener is actually listening on if you expect a connection as well as the IP that the server is on.

[DataMiser]

Also looks like there is a problem with your IP address.

If your server is on IP 123.456.789.0 and is Listening on Port 24000 then your client would need to try to connect to IP 123.456.789.0 on Port 24000.

If your client trys to connect to IP 456.123.789.0 It will not connect because that is not where your server is at. If your client tries to connect on port 1234 if will not connect because that is not the port you are listening to.

[Murjax]

I'm a little confused now. I fixed the port mistake, but I don't quite get what you mean when you say there's something wrong with my IP. I AM supposed to be listening on the localhost correct? The way I have it setup my server listens on the localhost and the client connects to it via the server's remote IP.

[dglienna]

If your server is on IP 123.456.789.0 and is Listening on Port 24000 then your client would need to try to connect to IP 123.456.789.0 on Port 24000.

That means, for you code to work, your server would have to be IP 123.456.789.0 on Port 24000 (on the server)

[DataMiser]

I'm a little confused now. I fixed the port mistake, but I don't quite get what you mean when you say there's something wrong with my IP. I AM supposed to be listening on the localhost correct? The way I have it setup my server listens on the localhost and the client connects to it via the server's remote IP.

The client would use the address of the server. If your server address is 127.0.0.1 as in your example above then your client would have to use 127.0.0.1

For example If you want to connect to Google you will not get there by typing in Yahoo.

Btw you can also use the machine name rather than a hard coded IP address. Works much better especially when the IP is DHCP controlled.

Dim hInfo As IPHostEntry = Nothing
Dim hIPAddress As IPAddress = Nothing
hInfo = Dns.GetHostEntry("Machine Name Here")
hIPAddress = hInfo.AddressList(0)

[Murjax]

That's how I originally thought the connection was supposed to work. The problem (as I stated some posts back) is that when I have the server listen on any IP other than 127.0.0.1 a SocketException is thrown saying that "The requested address is not valid in its context".

[DataMiser]

You must use an address that is valid on the machine where the server is being executed. This is your Local Host. The client must use that same IP address and port as the parameters for the connection.

Here is a bit of code from my server. Note I do not hard code any IP address.

Dim hInfo As System.Net.IPHostEntry = Dns.GetHostEntry(Dns.GetHostName)
Dim hIPAddress As IPAddress = Nothing
hIPAddress = hInfo.AddressList(0)

SocketHandler = New TcpListener(hIPAddress, hPort)  ' Set the IP AND Port Number
SocketHandler.Start()

[dglienna]

The question should have been WHEN DO I USE 127.0.0.1 on Both the CLIENT AND THE HOST?

That answer would be when both are running on the SAME MACHINE. You can run client and server on the same machine.