/// <summary>
/// Called when new data arrives. Checks to see how much data has arrived:
///
/// If 0: connection has been closed (presumably by the server)
/// If > 0: get SocketState out of stateAsArObject and call the callMe provided
/// </summary>
/// <param name="stateAsArObject">
/// SyncResult containing the SocketState where callMe is saved away.
/// </param>
public static void ReceiveCallback(IAsyncResult stateAsArObject)
{
SocketState ss = (SocketState)stateAsArObject.AsyncState;
try
{
if (ss.Connected)
{
int bytesRead = ss.TheSocket.EndReceive(stateAsArObject);
// If the socket is still open
if (bytesRead > 0)
{
string theMessage = Encoding.UTF8.GetString(ss.MessageBuffer, 0, bytesRead);
// Append the received data to the growable buffer.
// It may be an incomplete message, so we need to start building it up piece by piece
ss.SB.Append(theMessage);
}
ss.CallMe(ss);
}
}
catch (Exception e)
{
System.Diagnostics.Debug.WriteLine(e.Message);
ss.Connected = false;
}
}
/// <summary>
/// BeginAcceptSocket's callback function. When connection comes in, this method:
/// (1) extracts the state containing the TcpListener and the callMe function from ar.
/// (2) creates a new socket by using lister.EndAcceptSocket
/// (3) save socket in new SocketState
/// (4) call the callMe method and pass it to the new SocketState. This is how the server
/// gets a copy of the SocketState corresponding to this client. The callMe should
/// save the SocketState in a list of clients.
/// (5) Await a new connection request (coninued in the event loop) with BeginAcceptSocket.
/// This means that the networking code assumes we want to always continue the event loop.
/// </summary>
/// <param name="ar">contains the callMe and the TcpListener</param>
public static void AcceptNewClient(IAsyncResult ar)
{
ConnectionState cs = (ConnectionState)ar.AsyncState;
SocketState ss = new SocketState(cs.Lstn.EndAcceptSocket(ar), ++IDCounter);
ss.CallMe = cs.CallMe;
ss.CallMe(ss);
cs.Lstn.BeginAcceptSocket(AcceptNewClient, cs);
}
/// <summary>
/// Reference by BeginConnect above and is called when socket connects to
/// server. Once connection established, saved callMe is then called
/// (originally passed in the ConnectToServer in SocketState)
/// </summary>
/// <param name="stateAsArObject">
/// Contains a field "AsyncState" which contains SocketState saved away for
/// later use.
/// </param>
public static void ConnectedCallback(IAsyncResult stateAsArObject)
{
SocketState ss = (SocketState)stateAsArObject.AsyncState;
try
{
// Complete the connection.
ss.TheSocket.EndConnect(stateAsArObject);
System.Diagnostics.Debug.WriteLine("connected to server");
}
catch (Exception e)
{
System.Diagnostics.Debug.WriteLine("Unable to connect to server. Error occured: " + e);
return;
}
ss.CallMe(ss);
}