VB.Net 2005 : FAQ. Working with Local Network Connections.

[GremlinSA]

Q: How do I retrieve a list of Local IP Address?

A:
Imports System.Net

Public Function GetLIPAdresses() As ArrayList<O:p
Dim NetInterfaces() As NetworkInformation.NetworkInterface = NetworkInformation.NetworkInterface.GetAllNetworkInterfaces<O:p
Dim IPList As New ArrayList<O:p
Try<O:p
For Each NetInterface As NetworkInformation.NetworkInterface In NetInterfaces<O:p
Dim infosDns As NetworkInformation.UnicastIPAddressInformationCollection = NetInterface.GetIPProperties.UnicastAddresses<O:p
For Each address As NetworkInformation.UnicastIPAddressInformation In infosDns<O:p
IPList.Add(address.Address.ToString)<O:p
Next<O:p
Next<O:p
Catch ex As Exception<O:p
MessageBox.Show("Error: " & ex.Message)<O:p
End Try<O:p
Return IPList<O:p
End Function
'Code is thanks to aniskhan.



Q: How do I init a TCP port for linking (Listen or Client)

A:
Imports System.Net<O:p
Imports System.Text<O:p

Public Enum TCP_State<O:p
Listen<O:p
Conect<O:p
Client<O:p
End Enum<O:p
Private TCP_Listen As Sockets.TcpListener<O:p
Private TCP_Client As Sockets.TcpClient<O:p
Private Con_Method As TCP_State<O:p
Public Event Socket_Error(ByVal Err As Exception)<O:p

Public Function Init(ByVal Method As TCP_State, ByVal Port As Integer) As Boolean<O:p
Try<O:p
Con_Method = Method<O:p
Select Case Con_Method<O:p
Case TCP_State.Client<O:p
TCP_Client = New Sockets.TcpClient<O:p
Case TCP_State.Listen<O:p
TCP_Listen = New Sockets.TcpListener(L_IP, Port)<O:p
TCP_Listen.Start()<O:p
Case Else<O:p
Exit Function<O:p
End Select<O:p
C_Timer.Enabled = True<O:p
Init = True<O:p
Catch ex As Exception<O:p
Init = False<O:p
RaiseEvent Socket_Error(ex)<O:p
End Try<O:p
End Function

Q: How do I connect to a listening TCP port (Client)

A:
Public Function Connect(ByVal HostAddress As IPAddress, ByVal Port As Integer) As Boolean
Select Case Con_Method<O:p
Case TCP_State.Client<O:p
Try<O:p
TCP_Client.Connect(HostAddress, Port)<O:p
Return True<O:p
Catch ex As Exception<O:p
RaiseEvent Socket_Error(ex)<O:p
Return False<O:p
End Try<O:p
Case Else<O:p
Return False<O:p
End Select<O:p
End Function

Q: How do I accept a connection request to a listening TCP port


A: Because the Net class does not raise events, we need to use a timer to check if a connection request is pending, there after we can raise our own event.
Private WithEvents C_Timer As System.Windows.Forms.Timer
<O:p Public Event Connection_Request(ByVal Remote_IP As EndPoint)<O:p
Private Con_Proc As Boolean<O:p
Private Sub C_Timer_Elapsed(ByVal sender As Object, ByVal e As System.EventArgs) Handles C_Timer.Tick<O:p
Select Case Con_Method<O:p
Case TCP_State.Listen<O:p
If TCP_Listen.Pending Then<O:p
TCP_Client = TCP_Listen.AcceptTcpClient<O:p
RaiseEvent Connection_Request(TCP_Client.Client.RemoteEndPoint)<O:p
Con_Method = TCP_State.Conect<O:p
Con_Proc = True<O:p
' Close listening port... We've got our conection<O:p
TCP_Listen.Stop()<O:p
TCP_Listen = Nothing<O:p
End If<O:p
End Select<O:p
End Sub

Q: How do I check the connection status during a TCP connection


A: The following code snip runs in the same timer event as above. Public Event Connection_Complete(ByVal Remote_IP As EndPoint)
Public Event Connection_Error()
Private Sub C_Timer_Elapsed(ByVal sender As Object, ByVal e As System.EventArgs) Handles C_Timer.Tick
Select Case Con_Method
Case TCP_State.Client, TCP_State.Conect
If Con_Proc Then
If TCP_Client.Available > 0 Then
Try
ReDim RecievedBytes(TCP_Client.Available - 1)
TCP_Client.GetStream.Read(RecievedBytes, 0, TCP_Client.Available)
Tot_Array = UBound(B_Data) + 1
ReDim Preserve B_Data(Tot_Array)
ReDim Preserve B_Sender(Tot_Array)
ReDim Preserve Raw_Data(Tot_Array)
B_Data(Tot_Array) = Encoding.ASCII.GetString(RecievedBytes)
B_Sender(Tot_Array) = RemoteIpEndPoint.Address
Raw_Data(Tot_Array).Data = RecievedBytes
I_Timer.Enabled = True
Catch ex As Exception
RaiseEvent Socket_Error(ex)
End Try
End If
If Not TCP_Client.Connected Then
RaiseEvent Connection_Error()
End If
Else
If TCP_Client.Connected
RaiseEvent Connection_Complete(TCP_Client.Client.RemoteEndPoint)<O:p
Con_Proc = True<O:p
End If<O:p
End If<O:p
End Select<O:p
End Sub<O:p





<O:p

[GremlinSA]

The following FAQ questions refer to open TCP Connections

Q: How do I send my Data through an open connection?

A: It is the prefered method to send data in a byte array.
Public Function Send(ByVal Byte_ary() As Byte) As Boolean
Try
Select Case Con_Method
Case TCP_State.Client, TCP_State.Conect
TCP_Client.GetStream.Write(Byte_ary, 0, Byte_ary.GetUpperBound(0) + 1)
Case Else
Send = False
End Select
Catch ex As Exception
Send = False
RaiseEvent Socket_Error(ex)
End Try
End FunctionWhen the data is a string type variable the following can be used to sendTCP_Client.GetStream.Write(Encoding.ASCII.GetBytes(Data), 0, Encoding.ASCII.GetByteCount(Data))

Q: How do I Recieve my Data from an open connection?

A: Again because the Net class does not raise events we need to use a timer (even the same timer used to check for connection requests.) Public Event Data_Arrival(ByVal Data As String, ByVal Source As IPAddress)
Private B_Data As String
Private B_Sender As IPAddress
Private RecievedBytes() As Byte

If TCP_Client.Available > 0 Then
Try
ReDim RecievedBytes(TCP_Client.Available - 1)
TCP_Client.GetStream.Read(RecievedBytes, 0, TCP_Client.Available)
B_Data = Encoding.ASCII.GetString(RecievedBytes)
B_Sender = RemoteIpEndPoint.Address
RaiseEvent Data_Arrival(B_Data, B_Sender)
Catch ex As Exception
RaiseEvent Socket_Error(ex)
End Try
End If

Q: How do I close a TCP Connection.

A: The close command is dependant on the connection state of the TCP port. Public Function Close() As Boolean
Try
Select Case Con_Method
Case TCP_State.Client
TCP_Client.Close()
TCP_Client = Nothing
Case TCP_State.Listen
TCP_Listen.Stop()
TCP_Listen = Nothing
End Select
C_Timer.Enabled = False
Close = True
Catch ex As Exception
Close = False
End Try
End Function

[GremlinSA]

The following FAQ Questions apply to UDP connections.

Q: How do I send data to a UDP Socket?

A: As UDP is not tied to a specific destination, you need to specify the destination IP Address and port. Also again it is the preffered method to send data in a byte array. Public Function Send(ByVal Byte_Ary() As Byte, ByVal Address As IPEndPoint) As Boolean
Try
UDP_Sock.Send(Byte_Ary, Byte_Ary.GetUpperBound(0) + 1, Address)
Send = True
Catch ex As Exception
Send = False
RaiseEvent Socket_Error(ex)
End Try
End FunctionIf your data is in a string variable the following can be used to send dataUDP_Sock.Send(Encoding.ASCII.GetBytes(Data), Len(Data), Address)

Q: How do I recieve data from a UDP Socket?

A: Again because no events are raised by the Net Class, the following code needs to be in a timer. If UDP_Sock.Available > 0 Then
Try
RecievedBytes = UDP_Sock.Receive(RemoteIpEndPoint)
B_Data = Trim(Encoding.ASCII.GetString(RecievedBytes))
B_Sender = RemoteIpEndPoint.Address
RaiseEvent Data_Arrival(B_Data, B_Sender)
Catch ex As Exception
RaiseEvent Socket_Error(ex)
End Try
End If

Q: How do I close a UDP Socket?

A: Because the UDP socket is not bound or connected, does not have a state, you only need to close the socket Public Function Close() As Boolean
Try
UDP_Sock.Close()
UDP_Sock = Nothing
Close = True
Catch ex As Exception
Close = False
End Try
End Function