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Detect if there is a Dial up network connection

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Submitted on: 1/1/2015 12:01:00 PM
By: Newsgroup Posting (from psc cd)  
Level: Not Given
User Rating: By 40 Users
Compatibility: VB 5.0, VB 6.0
Views: 777
 
     Here is how I detect if there is a DUN (ISP) connection. You want to take a look at the Remote Access Services (RAS) APIs. They are fully documented at the Microsoft site. "J Gerard Olszowiec" entity@ns.sympatico.ca
 

Windows API/Global Declarations:

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'**************************************
'Windows API/Global Declarations for :Detect if there is a Dial up network connection
'**************************************
' Registry APIs.
Public Const HKEY_CLASSES_ROOT = &H80000000
Public Const HKEY_CURRENT_USER = &H80000001
Public Const HKEY_LOCAL_MACHINE = &H80000002
Public Const HKEY_USERS = &H80000003
Public Const HKEY_PERFORMANCE_DATA = &H80000004
Public Const HKEY_CURRENT_CONFIG = &H80000005
Public Const HKEY_DYN_DATA = &H80000006
Public Const ERROR_SUCCESS = 0&
Public Const APINULL = 0&
Public Const MAX_STRING_LENGTH As Integer = 256
Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal
hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As
Long
' RegQueryValueEx: If you declare the lpData parameter as String, you must
pass it By Value.
Declare Function RegQueryValueEx Lib "advapi32.dll" Alias
"RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal
lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As
Long
' Remote Access Services (RAS) APIs.
Public Const RAS_MAXENTRYNAME As Integer = 256
Public Const RAS_MAXDEVICETYPE As Integer = 16
Public Const RAS_MAXDEVICENAME As Integer = 128
Public Const RAS_RASCONNSIZE As Integer = 412
Public Type RasEntryName
dwSize As Long
szEntryName(RAS_MAXENTRYNAME) As Byte
End Type
Public Type RasConn
dwSize As Long
hRasConn As Long
szEntryName(RAS_MAXENTRYNAME) As Byte
szDeviceType(RAS_MAXDEVICETYPE) As Byte
szDeviceName(RAS_MAXDEVICENAME) As Byte
End Type
Public Declare Function RasEnumConnections Lib "rasapi32.dll" Alias
"RasEnumConnectionsA" (lpRasConn As Any, lpcb As Long, lpcConnections As
Long) As Long
Public Declare Function RasHangUp Lib "rasapi32.dll" Alias "RasHangUpA"
(ByVal hRasConn As Long) As Long
Public gstrISPName As String
Public ReturnCode As Long
code:
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'**************************************
' Name: Detect if there is a Dial up network connection
' Description:Here is how I detect if there is a DUN (ISP) connection. You want to take a look at the Remote Access Services (RAS) APIs. They are
fully documented at the Microsoft site."J Gerard Olszowiec" entity@ns.sympatico.ca
' By: Newsgroup Posting (from psc cd)
'**************************************

Public Function Connected_To_ISP() As Boolean
Dim hKey As Long
Dim lpSubKey As String
Dim phkResult As Long
Dim lpValueName As String
Dim lpReserved As Long
Dim lpType As Long
Dim lpData As Long
Dim lpcbData As Long
Connected_To_ISP = False
lpSubKey = "System\CurrentControlSet\Services\RemoteAccess"
ReturnCode = RegOpenKey(HKEY_LOCAL_MACHINE, lpSubKey, phkResult)
If ReturnCode = ERROR_SUCCESS Then
hKey = phkResult
lpValueName = "Remote Connection"
lpReserved = APINULL
lpType = APINULL
lpData = APINULL
lpcbData = APINULL
ReturnCode = RegQueryValueEx(hKey, lpValueName, lpReserved, lpType,
ByVal lpData, lpcbData)
lpcbData = Len(lpData)
ReturnCode = RegQueryValueEx(hKey, lpValueName, lpReserved, lpType,
lpData, lpcbData)
If ReturnCode = ERROR_SUCCESS Then
If lpData = 0 Then
' Not Connected
Else
' Connected
Connected_To_ISP = True
End If
End If
RegCloseKey (hKey)
End If
End Function
> 2) Once I determine that I'd like to disconnect, How do I do 
> that? It seems like I need some interface to DUN to do it.
Use RasHangUp. In this example I display a splash screen (frmHangupSplash)
while the hangup is in progress. You'll want to set gstrISPName =
Get_ISP_Name() before calling HangUp(), or better yet modify HangUP and
pass the DUN connection name (the ISP) as a parameter..
Public Sub HangUp()
Dim i As Long
Dim lpRasConn(255) As RasConn
Dim lpcb As Long
Dim lpcConnections As Long
Dim hRasConn As Long
frmHangupSplash.Show
frmHangupSplash.Refresh
lpRasConn(0).dwSize = RAS_RASCONNSIZE
lpcb = RAS_MAXENTRYNAME * lpRasConn(0).dwSize
lpcConnections = 0
ReturnCode = RasEnumConnections(lpRasConn(0), lpcb, lpcConnections)
' Drop ALL the connections that match the currect
' connections name.
If ReturnCode = ERROR_SUCCESS Then
For i = 0 To lpcConnections - 1
If Trim(ByteToString(lpRasConn(i).szEntryName)) =
Trim(gstrISPName) Then
hRasConn = lpRasConn(i).hRasConn
ReturnCode = RasHangUp(ByVal hRasConn)
End If
Next i
End If
' It takes about 3 seconds to drop the connection.
Wait (3)
While Connected_To_ISP
Wait (1)
Wend
Unload frmHangupSplash
End Sub
Public Sub Wait(sngSeconds As Single)
Dim sngEndTime As Single
sngEndTime = Timer + sngSeconds
While Timer < sngEndTime
DoEvents
Wend
End Sub
Public Function Get_ISP_Name() As String
Dim hKey As Long
Dim lpSubKey As String
Dim phkResult As Long
Dim lpValueName As String
Dim lpReserved As Long
Dim lpType As Long
Dim lpData As String
Dim lpcbData As Long
Get_ISP_Name = ""
If gblnConnectedToISP Then
lpSubKey = "RemoteAccess"
ReturnCode = RegOpenKey(HKEY_CURRENT_USER, lpSubKey, phkResult)
If ReturnCode = ERROR_SUCCESS Then
hKey = phkResult
lpValueName = "Default"
lpReserved = APINULL
lpType = APINULL
lpData = APINULL
lpcbData = APINULL
ReturnCode = RegQueryValueEx(hKey, lpValueName, lpReserved,
lpType, ByVal lpData, lpcbData)
lpData = String(lpcbData, 0)
ReturnCode = RegQueryValueEx(hKey, lpValueName, lpReserved,
lpType, ByVal lpData, lpcbData)
If ReturnCode = ERROR_SUCCESS Then
' Chop off the end-of-string character.
Get_ISP_Name = Left(lpData, lpcbData - 1)
End If
RegCloseKey (hKey)
End If
End If
End Function
'***************************************************************************
' Name: ByteToString
' ' Description:* * * THIS IS A FOLLOWUP SUBMISSION * * *
Purpose: Convert a string in byte format (usually from a DLL call) to a string of text.
PLEASE POST THIS AS A FOLLOWUP OR ADD TO THE CODE SAMPLE TITLED "Detect if there is a Dial up network connection" attributed to me J Gerard Olszowiec, entity@ns.sympatico.ca. The newsgroup post that you captured had a followup post that included the ByteToString code. I've been receiving requets for this functions code. Much Thanx. - Gerard
' By: Entity Software
'
' Inputs:None
' Returns:None
' Assumes:None
' Side Effects:None
'
'Code provided by Planet Source Code(tm) 'as is', without
' warranties as to performance, fitness, merchantability,
' and any other warranty (whether expressed or implied).
'***************************************************************************
Public Function ByteToString(bytString() As Byte) As String
 ' ' Convert a string in byte format (usually from a DLL call)
 ' ' to a string of text.
 Dim i As Integer
 ByteToString = ""
 i = 0
While bytString(i)0&
 ByteToString = ByteToString & Chr(bytString(i))
 i = i + 1
Wend
End Function


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