Help with clsping

[Whimp]

Hi,

We are usig the clsping.vb a class made for vb.net
When we use this class it works fine. But... When the ping encounters a machine that is turned off or doesn't exsit it crashes.
So we tried to call the ping between a try and catch but than the return values are always zero? Does anybody have experience with this class?

Greets,
Richard

 

[NoCoolHandle]

[COLOR=green white]
Does anybody have experience with this class?
[/color] not me... however how quickly do you need to know if the connection is up?

In vb6 we had used a single ping to establish if a server was up before making a sql connection. This enabled us to store data locally without having to wait for the 60 second network timeout.

I could dig up some code for you if you want..

Memory says it had a 20ms penalty for using it...

Just post back

 

[chrissie1]

So we tried to call the ping between a try and catch but than the return values are always zero? Does anybody have experience with this class?

give us the code you have there and we will look in to it.

Christiaan Baes
Belgium

If you want to get an answer read this FAQ faq796-2540
There's no such thing as a winnable war - Sting

 

[scf1964]

OK here is the code....what we want is reading several servers from a checked list box and check them if they are online, in other words if they give a reply......hope someone can help us further on the way.

thxs in advance

Robert


Option Explicit On

Imports System
Imports System.Net
Imports System.Net.Sockets

'* Class clsPing
'*
'* Author : Paulo S. Silva Jr.
'* Date : September 2002
'* Objective : Ping a host and return basic informations
'*
'* Class Properties
'*
'* +------------+-------------+-------------------------------------------------+
'* | Name | Type | Description |
'* +------------+-------------+-------------------------------------------------+
'* | DataSize | Integer | Size of the data to be send to the host |
'* | Identifier | Integer | Identifier of ping packet |
'* | Sequence | Integer | Sequence of the packet |
'* | LocalHost | IPHostEntry | Info for Local Computer |
'* | Host | Object | Host Entry for the remote computer |
'* +------------+-------------+-------------------------------------------------+
'*
'* Class Methods
'*
'* +-------------------+----------------------------------------------------+
'* | Name | Description |
'* +-------------------+----------------------------------------------------+
'* | PingHost | Pings the specified host |
'* +-------------------+----------------------------------------------------+
'*
'* Parts of the code based on information from Visual Studio Magazine
'* more info :

http://www.fawcette.com/vsm/2002_03/magazine/columns/qa/default.asp

'*
Public Class clsPing

Public Structure stcError
Dim Number As Integer
Dim Description As String
End Structure

Public Const PING_SUCCESS As Long = 0
Public Const PING_ERROR As Long = (-1)
Public Const PING_ERROR_BASE As Long = &H8000
Public Const PING_ERROR_HOST_NOT_FOUND As Long = PING_ERROR_BASE + 1
Public Const PING_ERROR_SOCKET_DIDNT_SEND As Long = PING_ERROR_BASE + 2
Public Const PING_ERROR_HOST_NOT_RESPONDING As Long = PING_ERROR_BASE + 3
Public Const PING_ERROR_TIME_OUT As Long = PING_ERROR_BASE + 4

Private Const ICMP_ECHO As Integer = 8
Private Const SOCKET_ERROR As Integer = -1

Private udtError As stcError

Private Const intPortICMP As Integer = 7
Private Const intBufferHeaderSize As Integer = 8
Private Const intPackageHeaderSize As Integer = 28

Private intDataSize As Byte
Private ipheLocalHost As System.Net.IPHostEntry
Private ipheHost As System.Net.IPHostEntry

Public Property DataSize() As Byte
Get
Return intDataSize
End Get
Set(ByVal Value As Byte)
intDataSize = Value
End Set
End Property

Public ReadOnly Property Identifier() As Byte
Get
Return 0
End Get
End Property

Public ReadOnly Property Sequence() As Byte
Get
Return 0
End Get
End Property

Public ReadOnly Property LocalHost() As System.Net.IPHostEntry
Get
Return ipheLocalHost
End Get
End Property

Public Property Host() As Object
Get
Return ipheHost
End Get
Set(ByVal Value As Object)
If (Value.GetType.ToString.ToLower = "system.string") Then
'*
'* Find the Host's IP address
'*
Try
ipheHost = System.Net.Dns.GetHostByName(Value)
Catch
ipheHost = Nothing
udtError.Number = PING_ERROR_HOST_NOT_FOUND
udtError.Description = "Host " & ipheHost.HostName & " not found."
End Try
ElseIf (Value.GetType.ToString.ToLower = "system.net.iphostentry") Then
ipheHost = (Value)
Else
ipheHost = Nothing
End If
End Set
End Property

'*
'* Class Constructor
'*
Public Sub New()
'*
'* Initializes the parameters
'*
intDataSize = 32
udtError = New stcError

'*
'* Get local IP and transform in EndPoint
'*
ipheLocalHost = System.Net.Dns.GetHostByName(System.Net.Dns.GetHostName())

'*
'* Defines Host
'*
ipheHost = Nothing
End Sub

'*
'* Function : PingHost
'* Author : Paulo dos Santos Silva Jr
'* Date : 05/09/2002
'* Objective : Pings a specified host
'*
'* Parameters : Host as String
'*
'* Returns : Response time in milliseconds
'* (-1) if error
'*
Public Function Ping() As Long

Dim intCount As Integer
Dim aReplyBuffer(255) As Byte

Dim intNBytes As Integer = 0

Dim intEnd As Integer
Dim intStart As Integer

Dim epFrom As System.Net.EndPoint
Dim epServer As System.Net.EndPoint
Dim ipepServer As System.Net.IPEndPoint

'*
'* Transforms the IP address in EndPoint
'*
ipepServer = New System.Net.IPEndPoint(ipheHost.AddressList(0), 0)
epServer = CType(ipepServer, System.Net.EndPoint)

epFrom = New System.Net.IPEndPoint(ipheLocalHost.AddressList(0), 0)

'*
'* Builds the packet to send
'*
DataSize = Convert.ToByte(DataSize + intBufferHeaderSize)

'*
'* The packet must by an even number, so if the DataSize is and odd number adds one
'*
If (DataSize Mod 2 = 1) Then
DataSize += Convert.ToByte(1)
End If
Dim aRequestBuffer(DataSize - 1) As Byte

'*
'* --- ICMP Echo Header Format ---
'* (first 8 bytes of the data buffer)
'*
'* Buffer (0) ICMP Type Field
'* Buffer (1) ICMP Code Field
'* (must be 0 for Echo and Echo Reply)
'* Buffer (2) checksum hi
'* (must be 0 before checksum calc)
'* Buffer (3) checksum lo
'* (must be 0 before checksum calc)
'* Buffer (4) ID hi
'* Buffer (5) ID lo
'* Buffer (6) sequence hi
'* Buffer (7) sequence lo
'* Buffer (8).. Ping Data
'*

'*
'* Set Type Field
'*
aRequestBuffer(0) = Convert.ToByte(ICMP_ECHO)

'*
'* Set ID field
'*
BitConverter.GetBytes(Identifier).CopyTo(aRequestBuffer, 4)

'*
'* Set Sequence
'*
BitConverter.GetBytes(Sequence).CopyTo(aRequestBuffer, 6)

'*
'* Load some data into buffer
'*
Dim i As Integer
For i = 8 To DataSize - 1
aRequestBuffer(i) = Convert.ToByte(i Mod 8)
Next i

'*
'* Calculate Checksum
'*
Call CreateChecksum(aRequestBuffer, DataSize, aRequestBuffer(2), aRequestBuffer(3))


'*
'* Try send the packet
'*
Try
'*
'* Create the socket
'*
Dim sckSocket As New System.Net.Sockets.Socket( _
Net.Sockets.AddressFamily.InterNetwork, _
Net.Sockets.SocketType.Raw, _
Net.Sockets.ProtocolType.Icmp)
sckSocket.Blocking = False

'*
'* Records the Start Time
'*
intStart = System.Environment.TickCount
sckSocket.SendTo(aRequestBuffer, 0, DataSize, SocketFlags.None, ipepServer)
intNBytes = sckSocket.ReceiveFrom(aReplyBuffer, SocketFlags.None, epServer)
intEnd = System.Environment.TickCount

If (intNBytes > 0) Then
'*
'* Informs on GetLastError the state of the server
'*
udtError.Number = (aReplyBuffer(19) * &H100) + aReplyBuffer(20)
Select Case aReplyBuffer(20)
Case 0 : udtError.Description = "Success"
Case 1 : udtError.Description = "Buffer too Small"
Case 2 : udtError.Description = "Destination Unreahable"
Case 3 : udtError.Description = "Dest Host Not Reachable"
Case 4 : udtError.Description = "Dest Protocol Not Reachable"
Case 5 : udtError.Description = "Dest Port Not Reachable"
Case 6 : udtError.Description = "No Resources Available"
Case 7 : udtError.Description = "Bad Option"
Case 8 : udtError.Description = "Hardware Error"
Case 9 : udtError.Description = "Packet too Big"
Case 10 : udtError.Description = "Reqested Timed Out"
Case 11 : udtError.Description = "Bad Request"
Case 12 : udtError.Description = "Bad Route"
Case 13 : udtError.Description = "TTL Exprd In Transit"
Case 14 : udtError.Description = "TTL Exprd Reassemb"
Case 15 : udtError.Description = "Parameter Problem"
Case 16 : udtError.Description = "Source Quench"
Case 17 : udtError.Description = "Option too Big"
Case 18 : udtError.Description = "Bad Destination"
Case 19 : udtError.Description = "Address Deleted"
Case 20 : udtError.Description = "Spec MTU Change"
Case 21 : udtError.Description = "MTU Change"
Case 22 : udtError.Description = "Unload"
Case Else : udtError.Description = "General Failure"
End Select
End If
sckSocket.Close()

Return (intEnd - intStart)
Catch oExcept As Exception
'
End Try

End Function

Public Function GetLastError() As stcError
Return udtError
End Function

' ICMP requires a checksum that is the one's
' complement of the one's complement sum of
' all the 16-bit values in the data in the
' buffer.
' Use this procedure to load the Checksum
' field of the buffer.
' The Checksum Field (hi and lo bytes) must be
' zero before calling this procedure.
Private Sub CreateChecksum(ByRef data() As Byte, ByVal Size As Integer, ByRef HiByte As Byte, ByRef LoByte As Byte)
Dim i As Integer
Dim chk As Integer = 0

For i = 0 To Size - 1 Step 2
chk += Convert.ToInt32(data(i) * &H100 + data(i + 1))
Next

chk = Convert.ToInt32((chk And &HFFFF&) + Fix(chk / &H10000&))
chk += Convert.ToInt32(Fix(chk / &H10000&))
chk = Not (chk)

HiByte = Convert.ToByte((chk And &HFF00) / &H100)
LoByte = Convert.ToByte(chk And &HFF)
End Sub

End Class