/// <summary>
/// This method will return the size of the buffer and assign
/// the contents of the ICMP packet to the buffer during the
/// calculation.
/// </summary>
/// <param name="packet">ICMP Packet to work with</param>
/// <param name="buffer">The buffer that will contain the information</param>
/// <returns>The size of the buffer</returns>
private static int Serialise(IcmpPacket packet, byte[] buffer)
{
int index = 0;
int packLen = packet.RetrieveData().Length;
byte[] type = new byte[1];
type[0] = packet.Type;
byte[] code = new byte[1];
code[0] = packet.SubCode;
byte[] chkSum = BitConverter.GetBytes(packet.Checksum);
byte[] id = BitConverter.GetBytes(packet.Identifier);
byte[] seq = BitConverter.GetBytes(packet.SequenceNumber);
Array.Copy( type, 0, buffer, index++, 1);
Array.Copy( code, 0, buffer, index++, 1);
Array.Copy( chkSum, 0, buffer, index, chkSum.Length);
index += chkSum.Length;
Array.Copy( id, 0, buffer, index, id.Length);
index += id.Length;
Array.Copy( seq, 0, buffer, index, seq.Length);
index += seq.Length;
Array.Copy( packet.RetrieveData(), 0, buffer, index, packLen);
index += packLen;
if ( index != packet.Size )
index = -1;
return index;
}
/// <summary>
/// Workout the checksum of the packet and assign it.
/// </summary>
/// <param name="packet">The packet to workout the checksum on.</param>
/// <param name="buffer">The buffer which contain the complete echo packet</param>
private static void ConvertBuffer(IcmpPacket packet, byte[] buffer)
{
// Get half size of the packet
double halfLen = Convert.ToDouble((packet.Size / 2));
double temp = Math.Ceiling(halfLen / 2);
int bufLen = Convert.ToInt32(temp);
// Create the byte array
UInt16[] chkSum = new UInt16[bufLen];
int bufIdx = 0;
for (int i = 0; i < bufLen; i++)
{
chkSum[i] = BitConverter.ToUInt16(buffer, bufIdx);
bufIdx += 2;
}
// Call method to return
packet.Checksum = CalculateChecksum(chkSum);
// Now we have the check sum Serialise again the the buffer
if (Serialise(packet, buffer) == -1)
{
throw new InvalidOperationException(SmartResourceManager.GetString("SD_002",
"Workshare.Common.Exceptions.Resources", Assembly.GetAssembly(typeof(SmartDetect)),
SmartResourceManager.CurrentCulture));
}
}
/// <summary>
/// Ping the computer name specified
/// </summary>
/// <param name="computerName">The computer to locate</param>
/// <returns>True if succesful</returns>
/// <remarks>IMPORTANT this code will throw a SocketException if the user does not belong to the local
/// admin group. This is due to the fact that Microsoft OS Windows 2000, XP, Windows Server 2003 do not
/// allow raw sockets to be created if the user does not belong to the local administrator group.</remarks>
/// <exception cref="ArgumentNullException">The computerName is empty</exception>
/// <exception cref="ArgumentException">Cannot resolve the computer name</exception>
/// <exception cref="SecurityException">Cannot access computer</exception>
/// <exception cref="InvalidOperationException">Cannot create the ICMP packet information</exception>
/// <exception cref="SocketException">If user does not belong to the local admin group</exception>
public static bool Ping(string computerName)
{
bool res = false;
// Set the destination of the echo packet
// and the sender address information
IPHostEntry dest = GetHost(computerName);
IPHostEntry sender = GetHost(".");
// Create the ICMP Packet Buffer
int packetSize = 0;
IcmpPacket packet = new IcmpPacket();
// Work out the buffer itself
packetSize = packet.RetrieveData().Length + 8;
byte[] icmpBuffer = new byte[packetSize];
int index = Serialise(packet, icmpBuffer);
if (index == -1)
{
throw new InvalidOperationException(SmartResourceManager.GetString("SD_002",
"Workshare.Common.Exceptions.Resources", Assembly.GetAssembly(typeof(SmartDetect)),
SmartResourceManager.CurrentCulture));
}
ConvertBuffer(packet, icmpBuffer);
res = SendData(sender, dest, icmpBuffer);
return res;
}
