Understanding Byte Array

[William]

After a short talk to Verrigan through PMs. I've decided to understand/code byte arrays. And after checking out his source now. Im starting to get a idea how its made.

To start with, he used this to give the arrays a name:

Code:

Public Sub InitMessages()
  HandleDataSub(SMsgGetClasses) = GetAddress(AddressOf HandleGetClasses)
...
End Sub

That is called from Sub InitServer(). Pretty logical.

This is were it become complicated, this code:

Code:

Sub HandleData(ByVal Index As Long, ByRef Buffer() As Byte)
On Error Resume Next
  Dim MsgType As Byte
  Dim StartAddr As Long
  
  MsgType = GetByteFromBuffer(Buffer, True)
  StartAddr = 0

  If aLen(Buffer) > 0 Then StartAddr = VarPtr(Buffer(0))
  
  If MsgType > SMSG_COUNT Then
    Call HackingAttempt(Index, "Packet Manipulation")
  Else
    Call CallWindowProc(HandleDataSub(MsgType), Index, StartAddr, aLen(Buffer), 0)
  End If
  If Err.Number  0 Then
    Call HackingAttempt(Index, "Packet Manipulation")
  End If
End Sub

Is the part that checks what packet is recieved. But I don't understand how that part can run a sub through:

Code:

Public Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal Index As Long, ByVal StartAddr As Long, ByVal ByteLen As Long, ByVal ExtraVar As Long) As Long

So if somebody knows that, please fill me in.

And after that, it's basicly just to copy the whole modBuffer to your game, and simply start changing the packets.

But now we have another odd thing, how can the program know what Parse belongs to which: GetIntegerFromBuffer(Buffer, True)

I give you a example how I mean:

Code:

Private Sub HandlePlayer(ByVal Index As Long, ByVal StartAddr As Long, ByVal ByteLen As Long, ByVal ExtraVar As Long)
  Dim Buffer() As Byte
  Dim MsgTo As Long
  Dim Msg As String
  
  Buffer = FillBuffer(StartAddr, ByteLen)
  
  If ValidateMessage(Index, Buffer) = 1 Then
    MsgTo = FindPlayer([b]GetStringFromBuffer(Buffer, True)[/b])
    
    If MsgTo  Index Then
      If MsgTo > 0 Then
        Msg = [b]GetStringFromBuffer(Buffer, True)[/b]
        
        Call AddLog(GetPlayerName(Index) & " tells " & GetPlayerName(MsgTo) & ", '" & Msg & "'", PLAYER_LOG)
        Call PlayerMsg(MsgTo, GetPlayerName(Index) & " tells you, '" & Msg & "'", TellColor)
        Call PlayerMsg(Index, "You tell " & GetPlayerName(MsgTo) & ", '" & Msg & "'", TellColor)
      Else
        Call PlayerMsg(Index, "Player is not online.", White)
      End If
    Else
      Call AddLog("Map #" & GetPlayerMap(Index) & ": " & GetPlayerName(Index) & " begins to mumble to himself, what a weirdo...", PLAYER_LOG)
      Call MapMsg(GetPlayerMap(Index), GetPlayerName(Index) & " begins to mumble to himself, what a weirdo...", Green)
    End If
  End If
End Sub

The two bold texts are two different string. Which are used for two different variables. Msg and MsgTo, and how come Msg doesnt get the MsgTo information? And vise versa. How does the buffer know which one to give what information. The same goes for when there are two or more integers that is being sent, how does the buffer know which one should be the Index and which one to be the itemnumber for example?

If I end up in success, I might make a small tutorial that will help you to convert the packets (this is if Verrigan dont mind). Cause I know he don't want everybody to get things served on a silver plate, but to actually understand what they'r doing.