Title:	Ping Class
Description:	How to ping a remote computer -- .NET Style
Author:	Paulo Santos
eMail:	pjondevelopment@gmail.com
Environment:	VB.NET (1.0, 1.1, 2.0), Visual Studio (2002, 2003, 2005)
Keywords:	Internet, Host, Ping

Ping Class

DISCLAIMER

The Software is provided "AS IS", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. in no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

Introduction

This is an old class of mine. I created this class when I was developing a server monitoring system back in 2002, and I reasoned that the easiest way to know if the server was up is to ping it.

So, I started searching the web and I found a code developed for C# and after a few bumps I converted to VB .NET and the code works fine, up to the point of performance.

I use the Socket class to create a packet of raw data to be sent to the host. The send part works fine, but the response (when I listen for the echo of the packet I just sent) takes ages to process. I've checked the docs on Microsoft about the ReceiveFrom method to see if they have some insight about what's going on, and finally found a solution.

Since then I have published this code in some other places, always with good feedback from my fellow developers friends.

When I decided to publish it on my website I knew I needed to take another look at this class because so much time has passed.

One of the things that always bothered me with this class is that it was synchronous, i.e. when you call the method to ping the host it doesn't return until the host responds or a time-out is reached.

Hence I decided to go through it once more and make a second version of it with asynchronous methods too. This way is up to you to use the method that suits best your application.

Note:

In the .NET Framework 2.0 there is a namespace called NetworkInformation where a new class called Ping what supersedes this class.

PingClass Members

Public Enumerators

pingErrorCodes
Enumerates the possible errors that might occur when pinging a remote host.

Public Enum pingErrorCodes As Integer    Success               = 0    Unknown               = (-1)    HostNotFound          = &H8001    SocketDidntSend       = &H8002    HostNotResponding     = &H8003    TimeOut               = &H8004    BufferTooSmall        = &H8101    DestinationUnreahable = &H8102    HostNotReachable      = &H8103    ProtocolNotReachable  = &H8104    PortNotReachable      = &H8105    NoResourcesAvailable  = &H8106    BadOption             = &H8107    HardwareError         = &H8108    PacketTooBig          = &H8109    ReqestedTimedOut      = &H810A    BadRequest            = &H810B    BadRoute              = &H810C    TTLExprdInTransit     = &H810D    TTLExprdReassemb      = &H810E    ParameterProblem      = &H810F    SourceQuench          = &H8110    OptionTooBig          = &H8111    BadDestination        = &H8112    AddressDeleted        = &H8113    SpecMTUChange         = &H8114    MTUChange             = &H8115    Unload                = &H8116    GeneralFailure        = &H8117End Enum

Public Constructors

PingClass Constructor
Initializes a new instance of the PingClass Class.

Public Sub New()

Public Properties

	`DataSize` Gets or sets the size of the package to be send on the ping request. Default 32 bytes. Public Property DataSize() As Byte
	`LastError` ReadOnly. The last error occurred when pinging a host. Public ReadOnly Property LastError() _ As pingErrorCodes
	`LocalHost` ReadOnly. A System.Net.IPHostEntry that represents the local computer. Public ReadOnly Property LocalHost() _ As System.Net.IPHostEntry
	`RemoteHost` A System.Net.IPHostEntry that represents the remote host to be pinged. Public Property RemoteHost() _ As System.Net.IPHostEntry
	`TimeOut` The amount of time in milliseconds in which the remote host must reply. Public Property TimeOut() As Long

Public Methods

	`BeginPing` Begins the asynchronous execution of a PING request to a specified host. Public Overloads Shared Function BeginPing( _ ByVal fqdnHostName As String, _ ByVal requestCallback As PingCallback, _ ByVal stateObject As Object) _ As PingAsyncResult Public Overloads Shared Function BeginPing( _ ByVal ipAddress As System.Net.IPAddress, _ ByVal requestCallback As PingCallback, _ ByVal stateObject As Object) _ As PingAsyncResult
	`EndPing` Ends an asynchronous PING request. Public Shared Sub EndPing( _ ByVal par As PingAsyncResult)
	`Ping` Pings the remote host and return the number of milliseconds that the host took to reply. Public Overloads Function Ping() As Long Public Overloads _ Shared Function Ping( _ ByVal fqdnHostName As String) As Long Public Overloads _ Shared Function Ping( _ ByVal ipAddress As System.Net.IPAddress) As Long
	`SetRemoteHost` Sets the RemoteHost Property. Public Overloads Sub SetRemoteHost( _ ByVal fqdnHostName As String) Public Overloads Sub SetRemoteHost( _ ByVal ipAddress As System.Net.IPAddress)

Using the code

For a quick and dirty sample just take a look at the follow snippet.

MsgBox("yahoo.com took " & _                  PingClass.Ping("yahoo.com") & _                                     " milliseconds to reply")

Yes, it is that easy.

Background information

Always a good source of information about the Internet is the "Request For Comments". More specifically about ping and ping request are:

RFC 792: Internet Control Message Protocol.
RFC 1122: Requirements for Internet Hosts -- Communication Layers.
RFC 1812: Requirements for IP Version 4 Routers.

PJ on Development