[Resolved] Button works once, then stops working.

[Monkz]

I am having issues with my program. It should update every time i click the button, but it runs through perfectly on the first click, after the first click it does nothing.

This is a UDP Program, where the client sends a packet with a sequence number and payload which are separate items in the packet. The server receives the packet, reads the sequence number, and then sends back the next sequence number the client should send.

The client then receives that from the server with the same payload.. And then should change its sequence number to the one it recieved, and send that to the server..

The client works up to where the client updates to the sequence number it receives from the server.. But both show no effect on any clicks after.

Heres my Client Code:

Option Strict Off
Imports System.Net.Sockets
 
Public Class Client
    Dim sequence As UInt64
    Private udp As UdpClient = Nothing
    Private client As UdpClient = Nothing
    Private packetReceived As Boolean = False
    Private endPoint As Net.IPEndPoint = Nothing
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        sequence = 1
        udp = New UdpClient()
        endPoint = New Net.IPEndPoint(Net.IPAddress.Any, 6000)
        client = New UdpClient(endPoint)
        Label1.Text = sequence
 
    End Sub
    Private Sub Form1_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown
        ReceivePackets()
    End Sub
 
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
 
    End Sub
 
    Private Sub ReceivePackets()
        Dim state As New UdpState(client, endPoint)
        client.BeginReceive(New AsyncCallback(AddressOf ReceiveCallback), state)
        While packetReceived = False
            Application.DoEvents()
            System.Threading.Thread.Sleep(100)
        End While
    End Sub
 
    Private Sub ReceiveCallback(ByVal ar As IAsyncResult)
        Dim state As UdpState = DirectCast(ar.AsyncState, UdpState)
        Dim u As UdpClient = state.UdpClient
        Dim e As Net.IPEndPoint = state.EndPoint
        Dim receiveBytes As Byte() = u.EndReceive(ar, e)
        Dim strem As New IO.MemoryStream(receiveBytes)
        Dim bf As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()
        Dim obj As Object = bf.Deserialize(strem)
        Dim pak As Packet = DirectCast(obj, Packet)
        'Display the packet on UI
        ShowPacketData(pak)
        packetReceived = True
    End Sub
 
    Private Delegate Sub ShowPacketDataCallback(ByVal pak As Packet)
    Private Sub ShowPacketData(ByVal pak As Packet)
 
        If Me.InvokeRequired Then
            sequence = pak.Sequence
            Me.Invoke(New ShowPacketDataCallback(AddressOf ShowPacketData), pak)
        Else
            TextBox1.Text = ("Server Received Sequence: " & pak.Sequence.ToString - 1)
            For Each b As Byte In pak.Payload
                TextBox2.Text &= b.ToString & " "
                Label1.Text = sequence
            Next
        End If
 
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        Dim payload As Byte() = New Byte() {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, _
                             11, 12, 13, 14, 15, 16, 17, 18, 19, 20, _
                             21, 22, 23, 24, 25, 26, 27, 28, 29, 30, _
                             31, 32, 33}
        Dim pak As New Packet(sequence, payload)
        Dim strem As New IO.MemoryStream()
        Dim bf As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()
        bf.Serialize(strem, pak)
        Dim stremByte() As Byte = strem.ToArray()
        udp.Connect("127.0.0.1", 5000)
        udp.Send(stremByte, stremByte.Length)
        strem.Close()
    End Sub
End Class

Heres my Server Code:

Option Strict Off
Imports System.Net.Sockets
 
Public Class Server
    Private client As UdpClient = Nothing
    Private packetReceived As Boolean = False
    Private endPoint As Net.IPEndPoint = Nothing
    Dim sequence As UInt64
    Private packetloss As Int64
    Private udp As UdpClient = Nothing
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        sequence = 1
        packetloss = 0
        endPoint = New Net.IPEndPoint(Net.IPAddress.Any, 5000)
        client = New UdpClient(endPoint)
        udp = New UdpClient()
        Label1.Text = sequence
    End Sub
 
    Private Sub Form1_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown
        ReceivePackets()
    End Sub
 
    Private Sub ReceivePackets()
        Dim state As New UdpState(client, endPoint)
        client.BeginReceive(New AsyncCallback(AddressOf ReceiveCallback), state)
        While packetReceived = False
            Application.DoEvents()
            System.Threading.Thread.Sleep(100)
        End While
    End Sub
 
    Private Sub ReceiveCallback(ByVal ar As IAsyncResult)
        Dim state As UdpState = DirectCast(ar.AsyncState, UdpState)
        Dim u As UdpClient = state.UdpClient
        Dim e As Net.IPEndPoint = state.EndPoint
        Dim receiveBytes As Byte() = u.EndReceive(ar, e)
        Dim strem As New IO.MemoryStream(receiveBytes)
        Dim bf As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()
        Dim obj As Object = bf.Deserialize(strem)
        Dim pak As Packet = DirectCast(obj, Packet)
        'Display the packet on UI
        ShowPacketData(pak)
        packetReceived = True
    End Sub
 
    Private Delegate Sub ShowPacketDataCallback(ByVal pak As Packet)
    Private Sub ShowPacketData(ByVal pak As Packet)
 
        If sequence = pak.Sequence Then
            sequence += 1
        Else
            packetloss += 1
        End If
 
 
        If Me.InvokeRequired Then
            Me.Invoke(New ShowPacketDataCallback(AddressOf ShowPacketData), pak)
        Else
            TextBox1.Text = pak.Sequence.ToString
            Label1.Text = sequence
            For Each b As Byte In pak.Payload
                TextBox2.Text &= b.ToString & " "
            Next
        End If
 
        Acknowledge()
 
    End Sub
 
    Private Sub Acknowledge()
 
        Dim payload2 As Byte() = New Byte() {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, _
                                            11, 12, 13, 14, 15, 16, 17, 18, 19, 20, _
                                            21, 22, 23, 24, 25, 26, 27, 28, 29, 30, _
                                            31, 32, 33}
        Dim pak As New Packet(sequence, payload2)
        Dim strem As New IO.MemoryStream()
        Dim bf As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()
        bf.Serialize(strem, pak)
        Dim stremByte() As Byte = strem.ToArray()
        udp.Connect("127.0.0.1", 6000)
        udp.Send(stremByte, stremByte.Length)
        strem.Close()
 
    End Sub
End Class

[stanav]

Read my last reply in your other thread.

[Monkz]

I believe i sent u a Private Message stating that i believed it had to be something to do with ReceivePackets(). I dont know where to move it, or how to change it without messing things up.

[stanav]

OK... Here is the revised code to work with a timer:

Form1 has 2 buttons and 1 timer. I used a random object to generate the values for the packets. Timer is set to 1 second interval.

Imports System.Net.Sockets

Public Class Form1

    'Use a random object to generate random packets
    Private rand As New Random()
    Private udp As UdpClient = Nothing
    Private bf As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter()

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        udp = New UdpClient()
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Start()
    End Sub

    Private Sub Form1_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown
        Dim frm2 As New Form2
        frm2.Show()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        SendPacket()
    End Sub

    Private Sub SendPacket()
        Dim sequence As UInt64 = CType(rand.Next(0, Integer.MaxValue), UInt64)
        Dim payload(32) As Byte
        For i As Integer = 0 To payload.GetUpperBound(0)
            payload(i) = CByte(rand.Next(0, 255))
        Next
        Dim pak As New Packet(sequence, payload)
        Using strem As New IO.MemoryStream()
            bf.Serialize(strem, pak)
            Dim stremByte() As Byte = strem.ToArray()
            udp.Connect("127.0.0.1", 5000)
            udp.Send(stremByte, stremByte.Length)
        End Using
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Timer1.Stop()
    End Sub
End Class

Nothing changed in Form2 except the ReceivePackets sub. Note that all I did was to move the client.BeginReceive line inside the loop.

Private Sub ReveivePackets()
        Dim state As New UdpState(client, endPoint)
        While True
            client.BeginReceive(New AsyncCallback(AddressOf ReceiveCallback), state)
            Application.DoEvents()
            System.Threading.Thread.Sleep(100)
        End While
    End Sub

[Monkz]

Thanks so much! This is the sort of thing i was trying to do! Im going to use the same idea, but i am going to not use the buttons.. Ill have the timer enabled on startup.
Thanks again!

[Monkz]

I changed it from 264 bit payload to 256 bit. How do i get the random payload thing to work with the change?

[stanav]

264 bits = 33 bytes (1 byte = 8 bits, remember?). So 256 bits = (256\8) bytes = 32 bytes. All you have to do is to change the payload size to 32 byte array, which is set in the Payload property of the Packet class. In that property, the setter is tests the size of the array to make sure it's of a certain size, and if it isn't, an exception is thrown.

[Monkz]

I had done that already. But when i use the random payload code you supplied i get:

"Payload must be a byte array of 32 element (32 bytes = 256 bits)"

[stanav]

This is the current code of the Payload Property

Public Property Payload() As Byte()
        Get
            Return _Payload
        End Get
        Set(ByVal value As Byte())
            If value.Length = 33 Then
                _Payload = value
            Else
                Throw New ArgumentException("Payload must be a byte array of 33 element (33 bytes = 264 bits)")
            End If
        End Set
    End Property

Do you see the number 33 in red? That needs to be changed to 32 if you want the payload to be 256 bits.

[Monkz]

This what i have:

 Public Property Payload() As Byte()
        Get
            Return _Payload
        End Get
        Set(ByVal value As Byte())
            If value.Length = 32 Then
                _Payload = value
            Else
                Throw New ArgumentException("Payload must be a byte array of 32 element (32 bytes = 256 bits)")
            End If
        End Set
    End Property

I did this earlier.

[Monkz]

It works before i change to the random code you supplied earlier, as long as i dont go over 32.

But i want to get what we have as 1 - 32 to be composed of random hexadecimal numbers from 1-9, A - F.


So Eg.

Instead of being in order from 1 - 32 as the very original code was, i might get randomly each time:

F, G, A, 1, 7 , 3, B etc... till im at 256 bits..

So i thought i could get that random code u use working, and then build onto it to make it work that way i just explained.. Just so far im getting this error.

[stanav]

1. Hexadecimal notation is only for displaying purpose.
2. 1 hex digit = 4 bits
3. So 1 byte = 8 bits = 2 hex digits.
4. You have an array of 32 bytes, and you want to populate that with random values, you just need to generate 32 random bytes and assign them to your array.
5. If you want to see the value of a byte in hex notation, you call Tostring("X") on that byte... Note that the leading zero will be dropped. So if you want to keep the leading zero, you have to add it yourself.
Try this:

        Dim b As Byte = 15
        Dim hex As String = b.ToString("X")
        MessageBox.Show(hex)
        Dim hexWithLeadingZero As String = b.ToString("X")
        If hex.Length < 2 Then
            hexWithLeadingZero = "0" & hex
        End If
        MessageBox.Show(hexWithLeadingZero)

[Monkz]

So on a new form application i came up with this:

Private Rand As New Random
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim b As Byte = CType(Rand.Next(1, 15), Byte)
        Dim hex As String = b.ToString("X")
        Dim hexWithLeadingZero As String = b.ToString("X")
        If hex.Length < 2 Then
            hexWithLeadingZero = "0" & hex
        End If
        MessageBox.Show(hexWithLeadingZero)
    End Sub

I believe this is close to what i need to achieve on my payload.. But i dont know how to apply this to all 32.

[stanav]

As I repeatedly say, 1 byte = 8 bits, and it can hold a value between 0-255 (inclusive).
So when you want to generate a random byte, you want to generate a value between 0 and 255, not between 1 and 14 as your code shows.

Dim b As Byte = CType(Rand.Next(0, 256), Byte)

That line of code generate 1 random byte. To generate 32 random bytes, you just need a loop of 32 iterations that executes that line in each iteration. Once you have a random byte, what you want to do with it (stick it in an array, for example) is up to you.

[Monkz]

should i also use Randomize for this?

[stanav]

should i also use Randomize for this?

No... Since you're coding in vb.net, you should stick with .net classes as much as possible. Use the System.Random class.

[Monkz]

So what approach would you suggest i do to get this random hexadecimal code to work in the project?

I tried to put it in, but when it converts to byte it says something like cant convert byte to 1-dimensional array of byte. On the line which makes it part of the packet.

[Monkz]

This is what i currently am using:

Private Sub Acknowledge()
 
        Dim x As Byte = CType(rand.Next(0, 256), Byte)
        Dim hex As String = x.ToString("X")
 
        If hex.Length < 2 Then
            hex = "0" & hex
        End If
 
        Dim payload2() As Byte = System.Text.Encoding.UTF32.GetBytes(hex)
 
        Dim pak As New Packet(sequence, payload2)
        Dim strem As New IO.MemoryStream()
 
        bf.Serialize(strem, pak)
        Dim stremByte() As Byte = strem.ToArray()
        udp.Connect("127.0.0.1", 6000)
        udp.Send(stremByte, stremByte.Length)
        strem.Close()
 
    End Sub

I bet its because i dont have it looping the hex yet, but i dont know how im going to do that and get all 32.

[stanav]

I don't know what to say... Can you go back and read post#12, item #1.
You don't send hex string in your packet. You just send a byte array. If you are curious and want to see what that byte array looks like in hex notation, you loop thru the array and acll tostring("x") to each byte, append it to an output string and display it in your UI. You do the same at the receiving end. But the data you send is still the byte array. You don't convert it to hex, because the hex string is just another representation of the actual value.

[Monkz]

So what im understanding is:

Dim Payload As Byte = CType(Rand.Next(0, 256), Byte)

And then the rest of the hex conversion i do to display directly to my UI?


Its the looping part that keeps confusing me though.. I can never get them to work..

Would i do somethine like Do Until intloop = 32, and each time at the end of the loop, i make intloop += 1?

[stanav]

'Declare a byte array with 32 element 
Dim payload(31) as Byte
'Now use a loop to generate random bytes to populate that array
For i as Integer = 0 to 31
   payload(i) = CType(Rand.Next(0, 256), Byte)
Next
'Now you have a 32-byte array filled with random bytes.... Do what you want with it.

[Monkz]

Thanks man! I wanted the server to send back the same random payload it received for the client. I got stuck on this one for awhile and was about to make another post but i got it! Probably not the best way to do it, but it is working perfectly.

The client sends the 32-byte array, which the server translates to its texbox in hexadecimal, and then resends the same array, which the client then translates to its textbox.. Upon testing they match!

Thanks so much for the help! Ill mark this as resolved.. Thanks again! You are great!