CODEWITHSUNDEEP
vb6icmp
IT researcher
IT researcher

Reputation: 3304

Check for internet connection gives error in windows 8

I Have a vb6 code which is used to test whether internet connection is there or not for a PC.I make use of checking google DNS for it.It works fine in Windows XP.But in Windows 8 if internet is connected or not it always returns success(Internet is connected). I am making use of Below is part of coding

Private Function CheckForInternet(ByVal ServerIP As String, ByRef IsTimedOut As Boolean) A

s Boolean
On Error GoTo CheckForInternet_EH

Dim Reply As ICMP_ECHO_REPLY
Dim lngSuccess As Long
Dim strIPAddress As String
Dim a As String
Dim startTimer As Single
Dim EndTimer As Single
Const Time_out_in_ms As Integer = 1000
'Get the sockets ready.
If SocketsInitialize() Then
    'Address to ping
    strIPAddress = ServerIP

    'Ping the IP that is passing the address and get a reply.
    lngSuccess = ping(strIPAddress, Time_out_in_ms, Reply)

    'Clean up the sockets.
    SocketsCleanup

    ''Return Value
    If lngSuccess = ICMP_SUCCESS Then
        CheckForInternet = True
    ElseIf lngSuccess = ICMP_STATUS_REQUEST_TIMED_OUT Then
        IsTimedOut = True
    End If
'Else
'    'Winsock error failure, initializing the sockets.
'    Debug.Print WINSOCK_ERROR
End If

Exit Function
CheckForInternet_EH:
Call msglog(Err.Description & Space(10) & "CheckForInternet", False)
End Function

And below is ping procedure

Public Function ping(ByVal sAddress As String, ByVal time_out As Long, Reply As ICMP_ECHO_REPLY) As Long
On Error GoTo ping_EH

Dim hIcmp As Long
Dim lAddress As Long
Dim lTimeOut As Long
Dim StringToSend As String

'Short string of data to send
StringToSend = "hello"

'ICMP (ping) timeout
lTimeOut = time_out ''ms

'Convert string address to a long representation.
lAddress = inet_addr(sAddress)

If (lAddress <> -1) And (lAddress <> 0) Then

    'Create the handle for ICMP requests.
    hIcmp = IcmpCreateFile()

    If hIcmp Then
        'Ping the destination IP address.
        Call IcmpSendEcho(hIcmp, lAddress, StringToSend, Len(StringToSend), 0, Reply, Len(Reply), lTimeOut)

        'Reply status
        ping = Reply.Status

        'Close the Icmp handle.
        IcmpCloseHandle hIcmp
    Else
        'Debug.Print "failure opening icmp handle."
        ping = -1
    End If
Else
    ping = -1
End If
Exit Function
ping_EH:
Call msglog(Err.Description & Space(10) & "ping", False)
End Function

It is only a part of coding(I do pass parameters properly such as sAddress with DNS of google etc).Now i have observed that when internet connection is there in windows xp ping = Reply.Status returns 0 (which is for success).Same is the case in Windows 8 also.But when internet connection is not there windows xp returns ping value as 11003(which means no internet connection).But in windows 8 it still returns 0 which is for success.

So i think it is problem with IcmpSendEcho function which returns wrong value

i have defined following also 

Private Declare Function IcmpSendEcho Lib "icmp.dll" _
   (ByVal IcmpHandle As Long, _
    ByVal DestinationAddress As Long, _
    ByVal RequestData As String, _
    ByVal RequestSize As Long, _
    ByVal RequestOptions As Long, _
    ReplyBuffer As ICMP_ECHO_REPLY, _
    ByVal ReplySize As Long, _
    ByVal Timeout As Long) As Long

'This structure describes the options that will be included in the header of an IP packet.
'http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcetcpip/htm/cerefIP_OPTION_INFORMATION.asp
Private Type IP_OPTION_INFORMATION
   Ttl             As Byte
   Tos             As Byte
   Flags           As Byte
   OptionsSize     As Byte
   OptionsData     As Long
End Type

'This structure describes the data that is returned in response to an echo request.
'http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcesdkr/htm/_wcesdk_icmp_echo_reply.asp
Public Type ICMP_ECHO_REPLY
   address         As Long
   Status          As Long
   RoundTripTime   As Long
   DataSize        As Long
   Reserved        As Integer
   ptrData                 As Long
   Options        As IP_OPTION_INFORMATION
   Data            As String * 250
End Type

Hint:also in link IcmpSendEcho IP_OPTION_INFORMATION for 64 bit pc is different etc.. etc.. In the link it is mentioned like "A buffer to hold any replies to the echo request. Upon return, the buffer contains an array of ICMP_ECHO_REPLY structures followed by the options and data for the replies. The buffer should be large enough to hold at least one ICMP_ECHO_REPLY structure plus RequestSize bytes of data." So i want to now how to declare ICMP_ECHO_REPLY32 and IP_OPTION_INFORMATION32 ?(i have used only ICMP_ECHO_REPLY and IP_OPTION_INFORMATION) So please help me to solve the problem

Upvotes: 2

Views: 1513

Answers (1)

mllamazares
mllamazares

Reputation: 8166

To check the internet connection I did this two simple functions:

Option Explicit
Private Declare Function InternetCheckConnectionA Lib "wininet.dll" (ByVal lpszUrl As String, ByVal dwFlags As Long, ByVal dwReserved As Long) As Long

Private Const FLAG_ICC_FORCE_CONNECTION  As Long = &H1

Public Function IsInternetOn() As Boolean
    IsInternetOn = InternetCheckConnectionA("http://www.google.com/", FLAG_ICC_FORCE_CONNECTION, 0&)
End Function

The second one:

Option Explicit
Private Declare Function InternetGetConnectedState Lib "wininet.dll" (ByRef lpdwFlags As Long, ByVal dwReserved As Long) As Long

Private Function IsInternetOn() As Boolean
   IsInternetOn = InternetGetConnectedState(0&, 0&)
End Function

Example of call:

Msgbox IsInternetOn()

Upvotes: 1

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