Checking if computer is online at startup

[PockyBum522]

Currently I'm using a ping script I got off here to check if the computer is online, but it tends to freeze the computer while it checks for a second if you're not online. Is there a better way to check online status, or a ping that doesn't freeze your program while checking if you're not online? (I sprinkled doevents liberally, didn't help)

 

[JustinEzequiel]

copied from API-Guide
does not cause freezing here but we're always connected at the office so YMMV

Private Const FLAG_ICC_FORCE_CONNECTION = &H1
Private Declare Function InternetCheckConnection Lib "wininet.dll" Alias "InternetCheckConnectionA" (ByVal lpszUrl As String, ByVal dwFlags As Long, ByVal dwReserved As Long) As Long
Private Sub Form_Load()
    'KPD-Team 2001
    'URL: [URL unfurl="true"]http://www.allapi.net/[/URL]
    'E-Mail: KPDTeam@Allapi.net
    If InternetCheckConnection("[URL unfurl="true"]http://www.allapi.net/",[/URL] FLAG_ICC_FORCE_CONNECTION, 0&) = 0 Then
        MsgBox "Connection to [URL unfurl="true"]http://www.allapi.net/[/URL] failed!", vbInformation
    Else
        MsgBox "Connection to [URL unfurl="true"]http://www.allapi.net/[/URL] succeeded!", vbInformation
    End If
End Sub

 

[PockyBum522]

It does seem to halt program execution if you're offline, but it seems to work well other than that, thank you though.

Here's the ping code if anyone's interested. I tried changin the PING_TIMEOUT to a low value to see if that might help, but no such luck. Why is that? I tried everything from 50, 10, 5, 1, .5 and .0001

And nothing helped ease the long time it took to get a result if you're offline.

Code:

Option Explicit

Private Const IP_STATUS_BASE As Long = 11000
Private Const IP_SUCCESS As Long = 0
Private Const IP_BUF_TOO_SMALL As Long = (11000 + 1)
Private Const IP_DEST_NET_UNREACHABLE As Long = (11000 + 2)
Private Const IP_DEST_HOST_UNREACHABLE As Long = (11000 + 3)
Private Const IP_DEST_PROT_UNREACHABLE As Long = (11000 + 4)
Private Const IP_DEST_PORT_UNREACHABLE As Long = (11000 + 5)
Private Const IP_NO_RESOURCES As Long = (11000 + 6)
Private Const IP_BAD_OPTION As Long = (11000 + 7)
Private Const IP_HW_ERROR As Long = (11000 + 8)
Private Const IP_PACKET_TOO_BIG As Long = (11000 + 9)
Private Const IP_REQ_TIMED_OUT As Long = (11000 + 10)
Private Const IP_BAD_REQ As Long = (11000 + 11)
Private Const IP_BAD_ROUTE As Long = (11000 + 12)
Private Const IP_TTL_EXPIRED_TRANSIT As Long = (11000 + 13)
Private Const IP_TTL_EXPIRED_REASSEM As Long = (11000 + 14)
Private Const IP_PARAM_PROBLEM As Long = (11000 + 15)
Private Const IP_SOURCE_QUENCH As Long = (11000 + 16)
Private Const IP_OPTION_TOO_BIG As Long = (11000 + 17)
Private Const IP_BAD_DESTINATION As Long = (11000 + 18)
Private Const IP_ADDR_DELETED As Long = (11000 + 19)
Private Const IP_SPEC_MTU_CHANGE As Long = (11000 + 20)
Private Const IP_MTU_CHANGE As Long = (11000 + 21)
Private Const IP_UNLOAD As Long = (11000 + 22)
Private Const IP_ADDR_ADDED As Long = (11000 + 23)
Private Const IP_GENERAL_FAILURE As Long = (11000 + 50)
Private Const MAX_IP_STATUS As Long = (11000 + 50)
Private Const IP_PENDING As Long = (11000 + 255)
Private Const PING_TIMEOUT As Long = 500
Private Const WS_VERSION_REQD As Long = &H101
Private Const MIN_SOCKETS_REQD As Long = 1
Private Const SOCKET_ERROR As Long = -1
Private Const INADDR_NONE As Long = &HFFFFFFFF
Private Const MAX_WSADescription As Long = 256
Private Const MAX_WSASYSStatus As Long = 128

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

Private Type ICMP_OPTIONS
Ttl As Byte
Tos As Byte
Flags As Byte
OptionsSize As Byte
OptionsData As Long
End Type

Public Type ICMP_ECHO_REPLY
Address As Long
status As Long
RoundTripTime As Long
DataSize As Long
'Reserved As Integer
DataPointer As Long
Options As ICMP_OPTIONS
Data As String * 250
End Type

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

Private Declare Function gethostbyname Lib "WSOCK32.DLL" _
(ByVal hostname As String) As Long

Private Declare Sub CopyMemory Lib "kernel32" _
Alias "RtlMoveMemory" _
(xDest As Any, _
xSource As Any, _
ByVal nbytes As Long)

Private Declare Function lstrlenA Lib "kernel32" _
(lpString As Any) As Long

Private Declare Function WSAStartup Lib "WSOCK32.DLL" _
(ByVal wVersionRequired As Long, _
lpWSADATA As WSADATA) As Long

Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long

Private Declare Function IcmpCreateFile Lib "icmp.dll" () As Long

Private Declare Function IcmpCloseHandle Lib "icmp.dll" _
(ByVal IcmpHandle As Long) As Long

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

Private Declare Function inet_addr Lib "WSOCK32.DLL" _
(ByVal s As String) As Long

'*****************************************
Public Function Ping(strAddress As String, strDataToSend As String, ECHO As ICMP_ECHO_REPLY) As Long


'If Ping succeeds :
'.RoundTripTime = time in ms for the ping to complete,
'.Data is the data returned (NULL terminated)
'.Address is the Ip address that actually replied
'.DataSize is the size of the string in .Data
'.Status will be 0
'
'If Ping fails .Status will be the error code

Dim lngPortHandle As Long
Dim lngAddress As Long

'convert the address into a long representation
lngAddress = inet_addr(strAddress)

'if dwAddress is valid
If lngAddress <> INADDR_NONE Then

'open a port
lngPortHandle = IcmpCreateFile()

'and if successful,
If lngPortHandle Then

'ping it.
Call IcmpSendEcho(lngPortHandle, _
lngAddress, _
strDataToSend, _
Len(strDataToSend), _
0, _
ECHO, _
Len(ECHO), _
PING_TIMEOUT)

'return the status as ping success
Ping = ECHO.status

'close the port handle
Call IcmpCloseHandle(lngPortHandle)

End If 'If hPort

Else:

'the address format was probably invalid
Ping = INADDR_NONE

End If

End Function


'*****************************************
Public Function GetStatusCode(lngStatus As Long) As String

Dim msg As String

Select Case lngStatus
Case IP_SUCCESS: msg = "ip success"
Case INADDR_NONE: msg = "inet_addr: bad IP format"
Case IP_BUF_TOO_SMALL: msg = "ip buf too_small"
Case IP_DEST_NET_UNREACHABLE: msg = "ip dest net unreachable"
Case IP_DEST_HOST_UNREACHABLE: msg = "ip dest host unreachable"
Case IP_DEST_PROT_UNREACHABLE: msg = "ip dest prot unreachable"
Case IP_DEST_PORT_UNREACHABLE: msg = "ip dest port unreachable"
Case IP_NO_RESOURCES: msg = "ip no resources"
Case IP_BAD_OPTION: msg = "ip bad option"
Case IP_HW_ERROR: msg = "ip hw_error"
Case IP_PACKET_TOO_BIG: msg = "ip packet too_big"
Case IP_REQ_TIMED_OUT: msg = "ip req timed out"
Case IP_BAD_REQ: msg = "ip bad req"
Case IP_BAD_ROUTE: msg = "ip bad route"
Case IP_TTL_EXPIRED_TRANSIT: msg = "ip ttl expired transit"
Case IP_TTL_EXPIRED_REASSEM: msg = "ip ttl expired reassem"
Case IP_PARAM_PROBLEM: msg = "ip param_problem"
Case IP_SOURCE_QUENCH: msg = "ip source quench"
Case IP_OPTION_TOO_BIG: msg = "ip option too_big"
Case IP_BAD_DESTINATION: msg = "ip bad destination"
Case IP_ADDR_DELETED: msg = "ip addr deleted"
Case IP_SPEC_MTU_CHANGE: msg = "ip spec mtu change"
Case IP_MTU_CHANGE: msg = "ip mtu_change"
Case IP_UNLOAD: msg = "ip unload"
Case IP_ADDR_ADDED: msg = "ip addr added"
Case IP_GENERAL_FAILURE: msg = "ip general failure"
Case IP_PENDING: msg = "ip pending"
Case PING_TIMEOUT: msg = "ping timeout"
Case Else: msg = "unknown msg returned"
End Select

GetStatusCode = CStr(lngStatus) & " [ " & msg & " ]"

End Function

'*****************************************
Public Function GetIPFromHostName(ByVal strHostName As String) As String

'converts a host name to an IP address.

Dim nbytes As Long
Dim ptrHosent As Long 'address of hostent structure
Dim ptrName As Long 'address of name pointer
Dim ptrAddress As Long 'address of address pointer
Dim ptrIPAddress As Long
Dim strAddress As String

strAddress = Space$(4)

ptrHosent = gethostbyname(strHostName & vbNullChar)

If ptrHosent <> 0 Then

'assign pointer addresses and offset

'ptrName is the official name of the host (PC).
'If using the DNS or similar resolution system,
'it is the Fully Qualified Domain Name (FQDN)
'that caused the server to return a reply.
'If using a local hosts file, it is the first
'entry after the IP address.
ptrName = ptrHosent

'Null-terminated list of addresses for the host.
'The Address is offset 12 bytes from the start of
'the HOSENT structure. Note: Here we are retrieving
'only the first address returned. To return more than
'one, define sAddress as a string array and loop through
'the 4-byte ptrIPAddress members returned. The last
'item is a terminating null. All addresses are returned
'in network byte order.
ptrAddress = ptrHosent + 12

'get the IP address
CopyMemory ptrName, ByVal ptrName, 4
CopyMemory ptrAddress, ByVal ptrAddress, 4
CopyMemory ptrIPAddress, ByVal ptrAddress, 4
CopyMemory ByVal strAddress, ByVal ptrIPAddress, 4

GetIPFromHostName = IPToText(strAddress)

End If

End Function


'*****************************************
Private Function IPToText(ByVal IPAddress As String) As String

IPToText = CStr(Asc(IPAddress)) & "." & _
CStr(Asc(Mid$(IPAddress, 2, 1))) & "." & _
CStr(Asc(Mid$(IPAddress, 3, 1))) & "." & _
CStr(Asc(Mid$(IPAddress, 4, 1)))

End Function

'*****************************************
Public Sub SocketsCleanup()

If WSACleanup() <> 0 Then
MsgBox "Windows Sockets error occurred in Cleanup.", vbExclamation
End If

End Sub


'*****************************************
Public Function SocketsInitialize() As Boolean

Dim WSAD As WSADATA

SocketsInitialize = WSAStartup(WS_VERSION_REQD, WSAD) = IP_SUCCESS

End Function
'*****************************************

Public Sub PingAddress(strAddressToResolve As String, strDataToSend As String)

Dim ECHO As ICMP_ECHO_REPLY
Dim logPos As Long
Dim lngSuccess As Long
Dim strIPAddress As String

If SocketsInitialize() Then

'convert the host name into an IP address
strIPAddress = GetIPFromHostName(strAddressToResolve)
Debug.Print "Resolved IP Address : " & strIPAddress

'ping the ip passing the address, text
'to use, and the ECHO structure
lngSuccess = Ping(strIPAddress, strDataToSend, ECHO)

'display the results
Debug.Print "Ping Status Code : " & GetStatusCode(lngSuccess)
Debug.Print "Echo Addess : " & ECHO.Address
Debug.Print "Round Trip Time : " & ECHO.RoundTripTime & " ms"
Debug.Print "Data Size : " & ECHO.DataSize & " bytes"

If Left$(ECHO.Data, 1) <> Chr$(0) Then
logPos = InStr(ECHO.Data, Chr$(0))
Debug.Print "Echo Data : " & Left$(ECHO.Data, logPos - 1)
End If

Debug.Print "Data Pointer : " & ECHO.DataPointer

Call SocketsCleanup

Else

MsgBox "Windows Sockets for 32 bit Windows " & _
"environments is not successfully responding."

End If

End Sub

 

[PockyBum522]

Even in the most simple ping code I could find, the timeout still seems to be ignored and it takes a while to return a result if you're offline.

Option Explicit

Const SOCKET_ERROR = 0
Const MAX_IP = 10

Private Type WSAdata
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 Type Hostent
h_name As Long
h_aliases As Long
h_addrtype As Integer
h_length As Integer
h_addr_list As Long
End Type

Private Type IP_OPTION_INFORMATION
TTL As Byte
Tos As Byte
Flags As Byte
OptionsSize As Long
OptionsData As String * 128
End Type

Private Type IP_ECHO_REPLY
Address(0 To 3) As Byte
Status As Long
RoundTripTime As Long
DataSize As Integer
Reserved As Integer
data As Long
Options As IP_OPTION_INFORMATION
End Type

Private Declare Function GetHostByName Lib "wsock32.dll" Alias "gethostbyname" (ByVal HostName As String) As Long
Private Declare Function WSAStartup Lib "wsock32.dll" (ByVal wVersionRequired&, lpWSAdata As WSAdata) As Long
Private Declare Function WSACleanup Lib "wsock32.dll" () As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, hpvSource As Any, ByVal cbCopy As Long)
Private Declare Function IcmpCreateFile Lib "icmp.dll" () As Long
Private Declare Function IcmpCloseHandle Lib "icmp.dll" (ByVal HANDLE As Long) As Boolean
Private Declare Function IcmpSendEcho Lib "ICMP" (ByVal IcmpHandle As Long, ByVal DestAddress As Long, ByVal RequestData As String, ByVal RequestSize As Integer, RequestOptns As IP_OPTION_INFORMATION, ReplyBuffer As IP_ECHO_REPLY, ByVal ReplySize As Long, ByVal Timeout As Long) As Boolean

Public Function Ping(sAddr As String, Optional Timeout As Integer = 20) As Integer
Dim hFile As Long, lpWSAdata As WSAdata
Dim hHostent As Hostent, AddrList As Long
Dim Address As Long, rIP As String
Dim OptInfo As IP_OPTION_INFORMATION
Dim EchoReply As IP_ECHO_REPLY

Call WSAStartup(&H101, lpWSAdata)

If GetHostByName(sAddr + String(64 - Len(sAddr), 0)) <> SOCKET_ERROR Then
CopyMemory hHostent.h_name, ByVal GetHostByName(sAddr + String(64 - Len(sAddr), 0)), Len(hHostent)
CopyMemory AddrList, ByVal hHostent.h_addr_list, 4
CopyMemory Address, ByVal AddrList, 4
End If

hFile = IcmpCreateFile()

If hFile = 0 Then
Ping = -2 ' MsgBox "Unable to Create File Handle"
Exit Function
End If

OptInfo.TTL = 255

If IcmpSendEcho(hFile, Address, String(32, "A"), 32, OptInfo, EchoReply, Len(EchoReply) + 8, Timeout) Then
rIP = CStr(EchoReply.Address(0)) + "." + CStr(EchoReply.Address(1)) + "." + CStr(EchoReply.Address(2)) + "." + CStr(EchoReply.Address(3))
Else
Ping = -1 ' MsgBox "Timeout"
End If

If EchoReply.Status = 0 Then
Ping = EchoReply.RoundTripTime
Else
Ping = -3
End If

IcmpCloseHandle hFile
WSACleanup

End Function

 

[JustinEzequiel]

can you ping from the command line?
the timeout switch (-w) works here

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

E:\Documents and Settings\justin>ping -h
Bad option -h.


Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]
            [-r count] [-s count] [[-j host-list] | [-k host-list]]
            [-w timeout] target_name

Options:
    -t             Ping the specified host until stopped.
                   To see statistics and continue - type Control-Break;
                   To stop - type Control-C.
    -a             Resolve addresses to hostnames.
    -n count       Number of echo requests to send.
    -l size        Send buffer size.
    -f             Set Don't Fragment flag in packet.
    -i TTL         Time To Live.
    -v TOS         Type Of Service.
    -r count       Record route for count hops.
    -s count       Timestamp for count hops.
    -j host-list   Loose source route along host-list.
    -k host-list   Strict source route along host-list.
    -w timeout     Timeout in milliseconds to wait for each reply.


E:\Documents and Settings\justin>

 

[PockyBum522]

Do you have code for getting data back from a command window? And I should use shell to run it, right? Thank you.

 

[JustinEzequiel]

There are a few posts by strongm in this forum about grabbing the output of a shell'ed program.
Will try to find these.
Try also searching on "shell and wait".

Alternatively, you could just redirect the output to a file then read that.

 

[JustinEzequiel]

the following may be helpful

http://www.tek-tips.com/viewthread.cfm?qid=255803

http://www.tek-tips.com/viewthread.cfm?qid=567909

will see if I can write/post some code later when I have time