Connected to Internet OR NOT Connected?

[rdcody]

Hey all,

I need to find out if the user is connected to the Internet. I've
looked at a ton of examples. Most of them have drawbacks to
using them because they don't work for every type of
connection. So I have an idea I want to clarify.....

It is my understanding that if I retrieve the local IP Address,
and it is 127.0.0.1, then the user is NOT connected. Right?
If so, is this always the case? I mean, is every computers
local IP Address 127.0.0.1 when they are not connected?

If all of this is right, why couldn't I use the following code...
(I don't know where I got this, so if it is yours...Thanks)

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'Put this in a Module:
Option Explicit

Public Const MIN_SOCKETS_REQD As Long = 1
Public Const WS_VERSION_REQD As Long = &H101
Public Const WS_VERSION_MAJOR As Long = WS_VERSION_REQD \ &H100 And &HFF&
Public Const WS_VERSION_MINOR As Long = WS_VERSION_REQD And &HFF&
Public Const SOCKET_ERROR As Long = -1
Public Const ERROR_SUCCESS = 0&
Public Const WSADESCRIPTION_LEN = 257
Public Const WSASYS_STATUS_LEN = 129
Public Const MAX_WSADescription = 256
Public Const MAX_WSASYSStatus = 128

Public Type WSAData
wVersion As Integer
wHighVersion As Integer
szDescription(0 To MAX_WSADescription) As Byte
szSystemStatus(0 To MAX_WSASYSStatus) As Byte
wMaxSockets As Integer
wMaxUDPDG As Integer
dwVendorInfo As Long
End Type

Type WSADataInfo
wVersion As Integer
wHighVersion As Integer
szDescription As String * WSADESCRIPTION_LEN
szSystemStatus As String * WSASYS_STATUS_LEN
iMaxSockets As Integer
iMaxUdpDg As Integer
lpVendorInfo As String
End Type

Public Type HOSTENT
hName As Long
hAliases As Long
hAddrType As Integer
hLen As Integer
hAddrList As Long
End Type

Declare Function WSAStartupInfo Lib "WSOCK32" Alias "WSAStartup" (ByVal wVersionRequested As Integer, lpWSADATA As WSADataInfo) As Long
Declare Function WSACleanup Lib "WSOCK32" () As Long
Declare Function WSAGetLastError Lib "WSOCK32" () As Long
Declare Function WSAStartup Lib "WSOCK32" (ByVal wVersionRequired As Long, lpWSADATA As WSAData) As Long
Declare Function gethostname Lib "WSOCK32" (ByVal szHost As String, ByVal dwHostLen As Long) As Long
Declare Function gethostbyname Lib "WSOCK32" (ByVal szHost As String) As Long
Declare Sub CopyMemoryIP Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, ByVal hpvSource As Long, ByVal cbCopy As Long)

Public Function GetIPAddress() As String
Dim sHostName As String * 256
Dim lpHost As Long
Dim HOST As HOSTENT
Dim dwIPAddr As Long
Dim tmpIPAddr() As Byte
Dim I As Integer
Dim sIPAddr As String
If Not SocketsInitialize() Then
GetIPAddress = ""
Exit Function
End If
If gethostname(sHostName, 256) = SOCKET_ERROR Then
GetIPAddress = ""
MsgBox "Windows Sockets error " & Str$(WSAGetLastError()) & " has occurred. Unable to successfully get Host Name."
SocketsCleanup
Exit Function
End If
sHostName = Trim$(sHostName)
lpHost = gethostbyname(sHostName)
If lpHost = 0 Then
GetIPAddress = ""
MsgBox "Windows Sockets are not responding. " & "Unable to successfully get Host Name."
SocketsCleanup
Exit Function
End If
CopyMemoryIP HOST, lpHost, Len(HOST)
CopyMemoryIP dwIPAddr, HOST.hAddrList, 4
ReDim tmpIPAddr(1 To HOST.hLen)
CopyMemoryIP tmpIPAddr(1), dwIPAddr, HOST.hLen
For I = 1 To HOST.hLen
sIPAddr = sIPAddr & tmpIPAddr(I) & "."
Next
GetIPAddress = Mid$(sIPAddr, 1, Len(sIPAddr) - 1)
SocketsCleanup
End Function

Public Function GetIPHostName() As String
Dim sHostName As String * 256
If Not SocketsInitialize() Then
GetIPHostName = ""
Exit Function
End If
If gethostname(sHostName, 256) = SOCKET_ERROR Then
GetIPHostName = ""
MsgBox "Windows Sockets error " & Str$(WSAGetLastError()) & " has occurred. Unable to successfully get Host Name."
SocketsCleanup
Exit Function
End If
GetIPHostName = Left$(sHostName, InStr(sHostName, Chr(0)) - 1)
SocketsCleanup
End Function

Public Function HiByte(ByVal wParam As Integer)
HiByte = wParam \ &H100 And &HFF&
End Function

Public Function LoByte(ByVal wParam As Integer)
LoByte = wParam And &HFF&
End Function

Public Sub SocketsCleanup()
If WSACleanup() <> ERROR_SUCCESS Then
MsgBox "Socket error occurred in Cleanup."
End If
End Sub

Public Function SocketsInitialize() As Boolean
Dim WSAD As WSAData
Dim sLoByte As String
Dim sHiByte As String
If WSAStartup(WS_VERSION_REQD, WSAD) <> ERROR_SUCCESS Then
MsgBox "The 32-bit Windows Socket is not responding."
SocketsInitialize = False
Exit Function
End If
If WSAD.wMaxSockets < MIN_SOCKETS_REQD Then
MsgBox "This application requires a minimum of " & CStr(MIN_SOCKETS_REQD) & " supported sockets."
SocketsInitialize = False
Exit Function
End If
If LoByte(WSAD.wVersion) < WS_VERSION_MAJOR Or (LoByte(WSAD.wVersion) = WS_VERSION_MAJOR And HiByte(WSAD.wVersion) < WS_VERSION_MINOR) Then
sHiByte = CStr(HiByte(WSAD.wVersion))
sLoByte = CStr(LoByte(WSAD.wVersion))
MsgBox "Sockets version " & sLoByte & "." & sHiByte & " is not supported by 32-bit Windows Sockets."
SocketsInitialize = False
Exit Function
End If
'must be OK, so lets do it
SocketsInitialize = True
End Function



'Put this in the Form:

Private Sub Command1_Click()
Text1.Text = GetIPAddress
End Sub

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So, the point is...if the returned local IP Address is 127.0.0.1,
then I know they are not connected, and can tell them they need
to be connected to do what I want them to do.

I hope this makes sense. I don't even know anymore because
I've been at this for about 6 hours straight.

Anyway, I sure would appreciate you guys checking this out, and
telling me what you think.

Thanks in advance,
Ron

[Michael_Kamen]

Originally posted by rdcody
It is my understanding that if I retrieve the local IP Address,
and it is 127.0.0.1, then the user is NOT connected. Right?
If so, is this always the case? I mean, is every computers
local IP Address 127.0.0.1 when they are not connected?
Ron

I might be mistaken, but isn't 127.0.1 just the LocalHost?

[rdcody]

Hey Michael,

I know I probably didn't explain myself very well.

Yes, I think that's the point ... IF every computers localhost is
127.0.0.1.

If you would run that example code I posted while your
connected to the Internet, the IP Address is different. When you
run it while your NOT connected to the Internet, the IP Address
is 127.0.0.1.

So...I guess my main two questions are...

Is every computers localhost IP Address 127.0.0.1?

And...

Do you see any problem with the above code that would
cause it not to work on every computer.

Thanks,
Ron

[jim mcnamara]

Your assumptions are wrong. In a LAN, systems are assigned permanent IP's. I have one 98 box, and can log on to it without connecting to the LAN - physically disconnected. MY IP address
Is still 10.bla.bla.bla.... My XP boxes can't let me log on without a LAN connection.

Generally only for dialup, and NOT for every single ISP out there, are local IP addresses undefined.

[Shawn N]

Private Declare Function InetIsOffline Lib "url.dll" (ByVal dwFlags As Long) As Long
Private Sub Form_Load()
    'KPD-Team 2001
    'URL: [url]http://www.allapi.net/[/url]
    'E-Mail: [email][email protected][/email]
    'InetIsOffline returns 0 if you're connected
    MsgBox "Are you connected to the internet? " + CStr(CBool(Not (InetIsOffline(0)))), vbInformation
End Sub

[ice_531]

I know theres many examples of internet connection right here in the API forum... and also i remember seeing something about it at www.vbcode.com

[petrus]

Originally posted by rdcody
Hey Michael,

I know I probably didn't explain myself very well.

Yes, I think that's the point ... IF every computers localhost is
127.0.0.1.

If you would run that example code I posted while your
connected to the Internet, the IP Address is different. When you
run it while your NOT connected to the Internet, the IP Address
is 127.0.0.1.

So...I guess my main two questions are...

Is every computers localhost IP Address 127.0.0.1?

And...

Do you see any problem with the above code that would
cause it not to work on every computer.

Thanks,
Ron

Well, It won't run very well on non-windows computers.

[Shawn N]

Originally posted by petrus
Well, It won't run very well on non-windows computers.

No VB coding will run well on non-Windows computers.