+- Mirage Engine (https://mirage-engine.uk/forums)
+-- Forum: Mirage Source (Nostalgia) (https://mirage-engine.uk/forums/forumdisplay.php?fid=61)
+--- Forum: Archive (2006-2011) (https://mirage-engine.uk/forums/forumdisplay.php?fid=18)
+---- Forum: General (https://mirage-engine.uk/forums/forumdisplay.php?fid=17)
+---- Thread: Understanding Byte Array (/showthread.php?tid=382)
Understanding Byte Array - William - 22-10-2006
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 SubThat 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 SubCode:
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 LongAnd 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 SubThe 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.
- William - 22-10-2006
Okay, so I figured out the last question I had on the topic.
Msg and MsgTo. The way you put them in the buffer in the client, the same order they should be called on the server.
For example client side:
Code:
Buffer = ""
Buffer = AddStringToBuffer(Buffer, MsgTo)
Buffer = AddStringToBuffer(Buffer, Text)And then serverside:
Code:
Buffer = FillBuffer(StartAddr, ByteLen)
If ValidateMessage(Index, Buffer) = 1 Then
MsgTo = FindPlayer(GetStringFromBuffer(Buffer, True))
If MsgTo Index Then
If MsgTo > 0 Then
Msg = GetStringFromBuffer(Buffer, True)
So now I understand that too
EDIT: Side question: did IOCP remove winsock? Im checking in MSE-Verrigan now, and noticed that the winsock control was removed.
- grimsk8ter11 - 22-10-2006
Yes it has =)
- Dragoons Master - 22-10-2006
Yes, when you change from winsock to IOCP, you dont need the winsock anymore so you can remove it. And CallWindowProc uses the memory pointer so its bit compicated to explain it all but basicly:
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 SubBuffer() is a ByteArray and you receive it from the Client as a ByteArray. Just in case: I'm considering that averybody knows what an array is. When it receives the packet it get's Buffer(0) which is the "packet ID"("playerdata", etc) and, using GetByteFromBuffer it get's it's ID and Saves into MsgType. Then to make it faster, instead of sending the hole buffer(which is the packet it selfs) to the specific HandleData Sub it saves the StartAddress of the buffer into a variable("StartAddr") and THEN it calls then CallWindowProc. This CallWindowProc just run the specific sub depending of what MsgType you have by checking from the memory IDs you seted in the InitMessages sub.
Plx Verrigan, correct me if I'm wrong but that's what I get from reading the code, I've taked a look a while ago but I never realy used it.
- William - 22-10-2006
grimsk8ter11 Wrote:Yes it has =)Okay, cause I didn't remember if it did
@Dragoons Master: Thanks for going indepth
Cause I really want to fully understand how all of it work. And now I noticed that changing to byte arrays will take a lot of time. But I guess it's worth it Keep the discussion going
- Obsidian - 27-10-2006
So you fill an array with the data being sent, and then the server sorts it back out in the order that it was sent in, but how does it know when to transfer from one value to the next, e.g., from data1 to data2 on the map editor, or whatever?
- Misunderstood - 27-10-2006
Obsidian Wrote:So you fill an array with the data being sent, and then the server sorts it back out in the order that it was sent in, but how does it know when to transfer from one value to the next, e.g., from data1 to data2 on the map editor, or whatever?
each value has a set number of bytes, for example, if there are integers, they each take 2 bytes(I think?). The client knows this, and reads the first 2 bytes as the first integer and the 2nd to bytes as the 2nd integer.
with Verrs system, once it reads the data it is expecting, it removes it from the byte array(I think?) so the next operation doesn't even have to know what came before it.
- Obsidian - 27-10-2006
oh okay. that actually makes a lot of sense.
- Obsidian - 03-11-2006
Editors?
Yeah....
so i'm assuming that based on verrigan's code, it just loads the entire rec for that particular item/spell/shop/w/e into the buffer at once and just sends that? That's what it looks like to me but i didn't quite get if that's what was going on or not.
And, when i mimicked the code for one of the editors i added for my game, it didn't work :?