/// <summary>
/// Begin processing the request by dispatching a <code>BeginProcessRequest</code>
/// invocation to an instance of an IHttpHandler class. If the processing fails
/// for any reason, the server responds with HTTP 400 Bad Request.
/// </summary>
/// <param name="wr"></param>
private void ProcessRequest(TcpServerWorkerRequest wr)
{
try
{
var context = new HttpContext(wr);
var app = _getInstance(context);
app.BeginProcessRequest(context, _handlerCompletionCallback, wr);
}
catch
{
try
{
// Send a bad request response if the context cannot
// be created for any reason.
wr.SendStatus(400, "Bad Request");
wr.SendKnownResponseHeader("Content-Type", "text/html; charset=utf8");
var body = Encoding.ASCII.GetBytes("<html><body>Bad Request</body></html>");
wr.SendResponseFromMemory(body, body.Length);
var response = wr.FlushResponse();
SendResponse(response);
wr.EndOfRequest();
}
finally
{
}
}
}
/// <summary>
/// Completes the request processing and initiates the process of
/// sending a response back to the client.
/// </summary>
/// <param name="wr"></param>
private void FinishRequest(TcpServerWorkerRequest wr)
{
// The following lines are a temporary stand-in while the rest
// of the application processing capabilities are being written.
wr.SendStatus(200, "OK");
wr.SendKnownResponseHeader("Content-Type", "text/html; charset=utf8");
var body = Encoding.ASCII.GetBytes("<html><body>Hello, world</body></html>");
wr.SendResponseFromMemory(body, body.Length);
var response = wr.FlushResponse();
SendResponse(response);
wr.EndOfRequest();
}
/// <summary>
/// Factory to create instances of the <code>TcpServerWorkerRequest</code> class.
/// </summary>
/// <param name="segment">An serialized byte array of the incoming request.</param>
/// <returns></returns>
internal static TcpServerWorkerRequest CreateWorkerRequest(byte[] segment)
{
if (null == segment)
{
throw new ArgumentNullException(nameof(segment));
}
if (0 == segment.Length)
{
throw new ArgumentException(nameof(segment.Length));
}
var wr = new TcpServerWorkerRequest(segment);
if (null != wr)
{
wr.Initialize();
}
return(wr);
}
/// <summary>
/// Initiates the incoming connection socket for the network server
/// and initialises an instance of the HttpApplication.
/// </summary>
/// <returns></returns>
public async void Start <T>(HttpApplicationFactory <T> factory) where T : IHttpAsyncHandler, new()
{
_getInstance = factory.GetApplicationInstance;
try
{
// Find an IPv4 address on the host computer and attempt to establish
// an incoming network socket over it on the specified port number.
var entries = await Dns.GetHostEntryAsync(_host);
if (0 == entries.AddressList.Length)
{
throw new Exception($"Could not bind to address on host {_host}");
}
IPAddress address = null;
foreach (var a in entries.AddressList)
{
if (AddressFamily.InterNetwork == a.AddressFamily)
{
address = a;
break;
}
}
var localEndPoint = new IPEndPoint(address, _port);
var listener = new Socket(localEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
listener.Bind(localEndPoint);
listener.Listen(10);
var incomingBuffer = new ArraySegment <byte>(new byte[1024]);
var message = new StringBuilder();
_handlerCompletionCallback = new AsyncCallback(OnHandlerCompletion);
// Go into an infinite loop and wait for incoming
// connections. When a connection is made, the application
// receives the message sent by the client and pumps it
// into the processing pipeline.
while (true)
{
_client = await listener.AcceptAsync();
var length = await _client.ReceiveAsync(incomingBuffer, SocketFlags.None);
message.Append(Encoding.ASCII.GetString(incomingBuffer.Array, 0, length));
Log.Verbose(message.ToString());
Log.Information("Received {length} bytes from client", length);
// Deserialize the incoming message buffer into a TcpServerWorkerRequest instance
var wr = TcpServerWorkerRequest.CreateWorkerRequest(incomingBuffer.Array);
ProcessRequest(wr);
}
}
catch (SocketException exception)
{
Log.Fatal($"Could not start a server at {_host}:{_port}.\r\nError: {exception.Message}");
}
catch (SecurityException exception)
{
Log.Fatal($"A security violation occurred while starting a server at {_host}:{_port}.\r\nError: {exception.Message}");
}
}
