Send UDP Packets in VBA
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Thread: Send UDP Packets in VBA

  1. #1
    Join Date
    Jun 2012
    Posts
    7

    Send UDP Packets in VBA

    First of all, Hello!

    Righto, I'm writing a program which will be used as a simple debugger app whilst developing/testing various reports at work. I have the debugger finished which listens for packets then displays the message in a listbox. This was written in VB in Visual Studio 11 Beta and it works fine. I can both send and receive message no problems.

    I did some googling and found some code which is supposed to send a UDP packet but for VB6/VBA so I can hook my *shudder* excel macro reports into my debugger too.

    According to it's replys, the code is working fine. It's sending the messages out, but my .net app isn't receiving them.
    Can anyone help me figure out what I'm doing wrong??

    Here's the VB code I'm using: (Converted to VB from the MSDN C++ code in the winsock help files. I didn't convert this, I just fixed any errors which arose and made it work with a message of any size.)

    Code:
    'reference
    'http://msdn.microsoft.com/en-us/library/windows/desktop/ms740673(v=vs.85).aspx
    Const INVALID_SOCKET = -1
    Const WSADESCRIPTION_LEN = 256
    
    Enum AF
      AF_UNSPEC = 0
      AF_INET = 2
      AF_IPX = 6
      AF_APPLETALK = 16
      AF_NETBIOS = 17
      AF_INET6 = 23
      AF_IRDA = 26
      AF_BTH = 32
    End Enum
    
    Enum sock_type
       SOCK_STREAM = 1
       SOCK_DGRAM = 2
       SOCK_RAW = 3
       SOCK_RDM = 4
       SOCK_SEQPACKET = 5
    End Enum
    
    Enum Protocol
       IPPROTO_ICMP = 1
       IPPROTO_IGMP = 2
       BTHPROTO_RFCOMM = 3
       IPPROTO_TCP = 6
       IPPROTO_UDP = 17
       IPPROTO_ICMPV6 = 58
       IPPROTO_RM = 113
    End Enum
    
    Type sockaddr
       sa_family As Integer
       sa_data(0 To 13) As Byte
    End Type
     
    Type sockaddr_in
      sin_family As Integer
      sin_port As Integer
      sin_addr(0 To 3) As Byte
      sin_zero(0 To 7) As Byte
    End Type
    
    Type socket
       pointer As Long
    End Type
    
    Type LPWSADATA_Type
       wVersion As Integer
       wHighVersion As Integer
       szDescription(0 To WSADESCRIPTION_LEN) As Byte
       szSystemStatus(0 To WSADESCRIPTION_LEN) As Byte
       iMaxSockets As Integer
       iMaxUdpDg As Integer
       lpVendorInfo As Long
    End Type
    
    Public Declare Function WSAGetLastError Lib "Ws2_32.dll" () As Integer
    Public Declare Function WSAStartup Lib "Ws2_32.dll" (ByVal wVersionRequested As Integer, ByRef lpWSAData As LPWSADATA_Type) As Long
    Public Declare Function sendto Lib "Ws2_32.dll" (ByVal socket As Long, ByRef buf() As Byte, ByVal length As Long, ByVal flags As Long, ByRef toaddr As sockaddr_in, tolen As Long) As Long
    Public Declare Function f_socket Lib "Ws2_32.dll" Alias "socket" (ByVal AF As Long, ByVal stype As Long, ByVal Protocol As Long) As Long
    Public Declare Function closesocket Lib "Ws2_32.dll" (ByVal socket As Long) As Long
    Public Declare Sub WSACleanup Lib "Ws2_32.dll" ()
    
    Sub SendPacket( Message As String, IP As String, Port As Integer)
       Dim ConnectSocket As socket
       Dim wsaData As LPWSADATA_Type
       Dim iResult As Integer : iResult = 0
       Dim send_sock As sock_type : send_sock = INVALID_SOCKET
       Dim iFamily As AF : iFamily = AF_INET
       Dim iType As Integer : iType = SOCK_DGRAM
       Dim iProtocol As Integer : iProtocol = IPPROTO_UDP
       Dim SendBuf(0 To 1023) As Byte
       Dim BufLen As Integer : BufLen = 1024
       Dim RecvAddr As sockaddr_in : RecvAddr.sin_family = AF_INET : RecvAddr.sin_port = Port
       Dim SplitArray As Variant : SplitArray = Split(IP, ".") 
    
       RecvAddr.sin_addr(0) = SplitArray(0)
       RecvAddr.sin_addr(1) = SplitArray(1)
       RecvAddr.sin_addr(2) = SplitArray(2)
       RecvAddr.sin_addr(3) = SplitArray(3)
    
       
       For Buf = 1 To Len( Message )
          SendBuf( Buf - 1 ) = Asc( Mid( Message, Buf, 1 ) )
       Next Buf
       SendBuf( Buf + 1 ) = 0
    
       iResult = WSAStartup(&H202, wsaData)
       If iResult <> 0 Then
          MsgBox ("WSAStartup failed: " & iResult)
          Exit Sub
       End If
    
       send_sock = f_socket(iFamily, iType, iProtocol)
       If send_sock = INVALID_SOCKET Then
          Errno = WSAGetLastError()
          Exit Sub
       End If
    
       iResult = sendto(send_sock, SendBuf, BufLen, 0, RecvAddr, Len(RecvAddr))
       If iResult = -1 Then
          MsgBox ("sendto failed with error: " & WSAGetLastError())
          closesocket (Send_Sock)
          Call WSACleanup
          Exit Sub
       End If
    
       iResult = closesocket(send_sock)
       If iResult <> 0 Then
          MsgBox ("closesocket failed with error : " & WSAGetLastError())
          Call WSACleanup
       End If
    End Sub
    I hope someone can assist!

  2. #2
    Join Date
    Jan 2006
    Location
    Chicago, IL
    Posts
    14,873

    Re: Send UDP Packets in VBA

    If it used any POINTERS to memory locations, that's where it doesn't convert AT ALL. Manual calculation of all POINTER types might be possible, though.
    David

    CodeGuru Article: Bound Controls are Evil-VB6
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    CodeGuru Reviewer
    2006 Dell CSP
    2006, 2007 & 2008 MVP Visual Basic
    If your question has been answered satisfactorily, and it has been helpful, then, please, Rate this Post!

  3. #3
    Join Date
    Jun 2012
    Posts
    7

    Re: Send UDP Packets in VBA

    Thanks for replying. I believe it does use pointers as the dll needs the strings of data, and the code conversion was passing the array ByReference.

    I'll have a look at manual pointers now anyway, thanks.

  4. #4
    Join Date
    Jan 2006
    Location
    Chicago, IL
    Posts
    14,873

    Re: Send UDP Packets in VBA

    VB6 doesn't know anything about pointers, or libraries that implement them.
    David

    CodeGuru Article: Bound Controls are Evil-VB6
    2013 Samples: MS CODE Samples

    CodeGuru Reviewer
    2006 Dell CSP
    2006, 2007 & 2008 MVP Visual Basic
    If your question has been answered satisfactorily, and it has been helpful, then, please, Rate this Post!

  5. #5
    Join Date
    Jun 2012
    Posts
    7

    Re: Send UDP Packets in VBA

    It appears to know about the undocumented StrPtr command, apparently.

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