public void Begin()
{
try
{
// Init socket for raw, IP based network listening.
_socket = new Socket(AddressFamily.InterNetwork,
SocketType.Raw,
ProtocolType.IP);
// Bind socket to IP and port.
_socket.Bind(new IPEndPoint(IPAddress, Port));
/* Configure socket to listen on all IP packets
** and include headers. */
_socket.SetSocketOption(SocketOptionLevel.IP,
SocketOptionName.HeaderIncluded,
true);
// State object for async callback.
SocketStateObject monObj = new SocketStateObject(_socket,
BufferSize);
// Set size of receive data buffer of socket.
_socket.ReceiveBufferSize = BufferSize;
/* Configure IO control to receive all incoming
** aswell as all out going data. */
_socket.IOControl(IOControlCode.ReceiveAll,
RCVALL_ON,
RCVALL_ON);
/* Start receiving data from clients.
** Store connection data in monObj.Data.
** Set data offset to 0 and use user defined
** buffer size. Do not pass any socket flags.
** Assign async callback and pass monObj as
** State object of the connection. */
_socket.BeginReceive(monObj.Data,
0, BufferSize,
SocketFlags.None,
new AsyncCallback(OnReceive),
monObj);
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
/* Async callback for Socket.BeginReceive.
** Stops when _continue is set to FALSE.
** IAsyncResult.AsyncState contains a SocketStateObject.
** Raises the PacketReceived event after parsing a valid packet.
** Raises the OnError event if anything failes. */
private void OnReceive(IAsyncResult ar)
{
/* Get SocketStateObject instance stored in
** the IAsyncResult.AsyncState object member. */
SocketStateObject monObj = ar.AsyncState as SocketStateObject;
if (null == monObj)
{
return;
} /* Check if SocketStateObject is null. */
if (!_continue)
{
TryRelease(monObj.Socket);
return;
} /* Continue receiving? */
try
{
// Get socket from SocketStateObject.
Socket socket = monObj.Socket;
if (null == socket)
{
return;
} /* Check if received Socket is null. */
// Stores any socket error.
SocketError err;
// Amount of bytes received from Socket.
int nReceived = socket.EndReceive(ar, out err);
// Allocate byte array to store received bytes.
byte[] bytesReceived = new byte[nReceived];
// Event args for PacketEventArgs.
PacketEventArgs ipArgs = null;
if (1 > nReceived)
{
if (SocketError.Success == err)
{
// Assign SocketError.NoData.
err = SocketError.NoData;
} /* Check if we ran into any errors. */
/* Create event args with no header object,
** the IP address, the port and the SocketError. */
ipArgs = new PacketEventArgs(null,
IPAddress,
Port,
err);
} /* No data received. */
else
{
// Copy received bytes to array.
Buffer.BlockCopy(monObj.Data,
0,
bytesReceived,
0,
nReceived);
/* Create event args with header object,
** IP address, port and no error. */
ipArgs = new PacketEventArgs(bytesReceived,
IPAddress,
Port);
} /* Data received. */
// Raise event.
OnPacketReceived(ipArgs);
// Create new SocketStateObject instance.
monObj = new SocketStateObject(socket, BufferSize);
// Continue receiving raw packets.
socket.BeginReceive(monObj.Data, 0,
BufferSize,
SocketFlags.None,
new AsyncCallback(OnReceive),
monObj);
}
catch (Exception ex) {
// Create new error event args.
var errArgs = new PacketErrorEventArgs(
ex, _socket, IPAddress, Port);
// Raise error event.
OnErrorInternal(errArgs);
}
}