https://github.com/quackster/mythos
Experimental DLL calling for VL64/B64 encoding for the Habbo Hotel protocol from within Visual Basic 6.0.
https://github.com/quackster/mythos
Last synced: 5 months ago
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Experimental DLL calling for VL64/B64 encoding for the Habbo Hotel protocol from within Visual Basic 6.0.
- Host: GitHub
- URL: https://github.com/quackster/mythos
- Owner: Quackster
- Created: 2023-09-09T05:27:38.000Z (almost 3 years ago)
- Default Branch: master
- Last Pushed: 2024-05-12T00:30:19.000Z (about 2 years ago)
- Last Synced: 2025-05-19T02:11:47.834Z (about 1 year ago)
- Language: Visual Basic 6.0
- Homepage:
- Size: 988 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
## Mythos
Experimental DLL calling for VL64/B64 encoding for the Habbo Hotel protocol from within Visual Basic 6.0
## Screenshot
## Code Snippets
```vb
Private Sub MainServer_DataArrival(Index As Integer, ByVal bytesTotal As Long)
Dim incomingMessage As String
Dim incomingMessageLength As Long
Dim pointer As Long
pointer = 1
Dim packetLength As Long
Dim packetHeader As String
Dim packetData As String
' Check if there are at least 5 bytes available to read the packet length and the first character of data
If MainServer(Index).BytesReceived >= 5 Then
' Read the buffer
MainServer(Index).GetData incomingMessage
incomingMessageLength = MainServer(Index).BytesReceived
Do
' Harvest packet length
packetLength = DecodeB64(Mid(incomingMessage, pointer, 3))
pointer = pointer + 3
If packetLength <= 0 Or packetLength > 1000 Then
' Invalid packet length
Exit Sub
End If
' Check if there are enough bytes available to read the entire packet
If bytesTotal < packetLength Then Exit Do
' Harvest packet header
packetHeader = Mid(incomingMessage, pointer, 2)
pointer = pointer + 2
' Harvest packet data
packetData = Mid(incomingMessage, pointer, packetLength - 2)
pointer = pointer + packetLength - 2
' Create request class
Dim requestMessage As New clsRequestMessage
requestMessage.Buffer = packetData
requestMessage.Header = packetHeader
' Create data handler class
Dim dataHandler As New clsDataHandler
dataHandler.Index = Index
Set dataHandler.Buffer = requestMessage
' Handle packets
Call dataHandler.Parse
Loop While Len(Mid(incomingMessage, pointer)) > 0
End If
End Sub
```
## Requirements
- Visual Basic 6.0 IDE
- Your project is compiling under 'native' and **not** P-code, the DLL calls will not work otherwise
- [tdm-gcc 32-bit](https://jmeubank.github.io/tdm-gcc/) for Windows; or
- Packages ``g++ gcc oleaut32`` for Linux/Unix systems
### How it works
*C++ Code*
Copying strings back to the memory allocated Visual Basic 6.0 string, this is probably very evil, but it works!
```c
void copystr(LPSTR destination, long destinationLength, std::string output) {
int j = 0;
for (int i = 0; i <= destinationLength; i += 2) {
char ch = *(destination + i);
if (ch == '\0' || output[j] == '\0')
break;
*(destination + i) = output[j];
j++;
if (j >= output.length())
break;
}
}
```
The actual 'EncodeInt32' function
```c
void encodeVL64(/*LPSTR*/char *destination, long destinationLength, int *outputLength, int i) {
int numBytes = 0;
char* wf = (char*)malloc(6);
int pos = 0;
numBytes = 1;
int startPos = pos;
int negativeMask = i >= 0 ? 0 : 4;
i = abs(i);
wf[pos++] = (char)(64 + (i & 3));
for (i >>= 2; i != 0; i >>= 6) {
numBytes++;
wf[pos++] = (char)(64 + (i & 0x3F));
}
wf[startPos] = (char)(wf[startPos] | (numBytes << 3) | negativeMask);
// Skip the null bytes in the result
char* bzData = (char*)malloc(numBytes + 1);
for (int x = 0; x < numBytes; x++) {
bzData[x] = wf[x];
}
bzData[numBytes] = '\0';
// Copy to allocated VB6 string
std::string allocated(bzData);
copystr(destination, destinationLength, allocated);
// Free memory
free(wf);
free(bzData);
*outputLength = numBytes;
}
```
*Visual Basic 6.0 code*
Run ``dumpbin.exe /exports shared_lib.dll`` on our shared DLL file.
You will see:
```
Dump of file shared_lib.dll
File Type: DLL
Section contains the following exports for shared_lib.dll
0 characteristics
663EC498 time date stamp Sat May 11 11:06:32 2024
0.00 version
1 ordinal base
4 number of functions
4 number of names
ordinal hint RVA name
1 0 000015B9 decodeB64@4
2 1 00001526 decodeVL64@8
3 2 00001627 encodeB64@12
4 3 00001278 encodeVL64@16
```
The 'EncodeInt32@16' is the exported function name we'll use.
```vb
Option Explicit
Private Declare Sub DllEncodeVL64 Lib "shared_lib.dll" _
Alias "encodeVL64@16" ( _
ByVal inputPtr As Long, _
ByVal inputLength As Long, _
ByRef outputLength As Integer, _
ByVal i As Long _
)
Private Declare Function DllDecodeVL64 Lib "shared_lib.dll" _
Alias "decodeVL64@8" ( _
ByVal bzData As String, _
ByRef totalBytes As Long _
) As Long
Public Function EncodeVL64(ByVal i As Long) As String
Dim encodedVal As String
Dim outputLength As Integer
encodedVal = Space(6)
outputLength = 0
Call DllEncodeVL64(StrPtr(encodedVal), LenB(encodedVal), outputLength, i)
If (outputLength = 0) Then
EncodeVL64 = vbNullString
Else
EncodeVL64 = Mid(encodedVal, 1, outputLength)
End If
End Function
Public Function DecodeVL64(ByVal encodedValue As String, ByRef totalBytes As Long) As Long
DecodeVL64 = DllDecodeVL64(encodedValue, totalBytes)
End Function
```
## Building the DLL
*Windows*
```
C:\TDM-GCC-32\bin\g++.exe -std=c++11 -U__STRICT_ANSI__ -c -DBUILD_MY_DLL shared_lib.cpp
C:\TDM-GCC-32\bin\g++.exe -L. -loleaut32 -shared -o shared_lib.dll shared_lib.o -Wl,--out-implib,libshared_lib.a,--enable-stdcall-fixup
```
*Linux/Unix*
```
g++ -std=c++11 -U__STRICT_ANSI__ -c -DBUILD_MY_DLL shared_lib.cpp
g++ -L. -loleaut32 -shared -o shared_lib.dll shared_lib.o -Wl,--out-implib,libshared_lib.a,--enable-stdcall-fixup
```