View source for Buffering TCP Data

When working with TCP, you cannot guarantee that data will arrive in the way it was sent.  That is to say that if one set of packets arrives before another set of packets, you could end up with only half the data you expected in one message.  What this means is that it is necessary to buffer TCP data until you receive your delimeter character(s) (usually \r\n, or vbCrLf) before processing it.  The following is a simple solution to this problem - 

Add a class module to your project, and call it something like CTcpBuffer, then paste the following code into it:

    Option Explicit
    
    Public Delimiter As String
    
    Dim Buff As String
    
    Public Event WalkBuff(ByVal Data As String)
    
    Private Sub Class_Initialize()
        Delimiter = vbCrLf
    End Sub
    
    Public Sub AddData(ByVal Data As String)
        Buff = Buff & Data
    End Sub
    
    Public Function GetData(ByVal Length As Long) As String
        Dim ret As String
        ret = Left$(Buff, Length)
        Buff = Mid$(Buff, Length + 1)
        GetData = ret
    End Function
    
    Public Sub WalkBuffer()
        Do While InStr(Buff, Delimiter) > 0
            RaiseEvent WalkBuff(GetData(InStr(Buff, Delimiter) + Len(Delimiter) - 1))
        Loop
    End Sub
    
    Public Property Get Buffer() As String
        Buffer = Buff
    End Property

Then use the code as follows:

    Dim WithEvents mTcpBuffer As CTcpBuffer
    
    Private Sub Form_Load()
        Set mTcpBuffer = New CTcpBuffer
        mSocket.Connect "someserver", 1234
    End Sub
    
    Private Sub Form_Terminate()
        Set mTcpBuffer = Nothing
        mSocket.Close
    End Sub
    
    Private Sub mSocket_DataArrival(ByVal BytesTotal As Long)
        Dim sData As String
        
        mSocket.GetData sData, vbString, BytesTotal
        
        mTcpBuffer.AddData sData
        mTcpBuffer.WalkBuffer
    End Sub
    
    Private Sub mTcpBuffer_WalkBuff(ByVal Data As String)
        '-- Process Data Here
        mSocket.Close
    End Sub

Simple as that.  The class even has features for when you want to use something other than \r\n as a delimiter (though you shouldn't ever, really).