/// <summary>
/// Passes the given response message to the endpoint.
/// </summary>
/// <param name="response"></param>
public void PassResponse(ProxyMessage response, Socket clientSocket)
{
// Send the response to the client
if (clientSocket != null && clientSocket.Connected)
{
clientSocket.Send(response.Content);
}
}
/// <summary>
/// Passes the given client message to the given endpoint.
/// </summary>
/// <param name="message">The message of the client and his endpoint.</param>
/// <param name="dstEP">The endpoint that will receive the client's message</param>
public void PassClientMessage(ProxyMessage message, IPEndPoint dstEP)
{
// Build the message in our proxy format:
// <endpoint_bytes><client_message>
var ipBytes = message.ClientEndpoint.Address.GetAddressBytes();
var portBytes = BitConverter.GetBytes(message.ClientEndpoint.Port).Take(PORT_LENGTH_IN_BYTES).ToArray();
byte[] messageToSend = ipBytes.Concat(portBytes).Concat(message.Content).ToArray();
// Send the proxy-formatted message to the destination
Socket socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
try
{
socket.Connect(dstEP);
}
catch
{
throw new Exception("Connection to server failed.");
}
socket.Send(messageToSend);
}
static void Main(string[] args)
{
// Load all the servers from the configuration file in a constant interval
Thread serverLoadingThread = new Thread(() =>
{
while (true)
{
HashSet <IPEndPoint> addedServers = LoadServers(SERVERS_FILE);
//Console.WriteLine("Reloading servers...");
// Add the new servers to the Load Balancer
foreach (var server in addedServers)
{
lock (_loadBalancer)
{
_loadBalancer.AddLoadCarrier(server);
}
}
// Sleep for ten Seconds
Thread.Sleep(SECOND);
}
});
serverLoadingThread.Start();
// Start the status-printing thread
Thread statusPrintingThread = new Thread(() =>
{
while (true)
{
PrintLoadBalancingStatus();
Thread.Sleep(100);
}
});
statusPrintingThread.Start();
// Set-up the server and start listening for client-requests and server-responses
ProxyServer proxyServer = new ProxyServer(SERVE_PORT, PROXY_PORT);
proxyServer.Start();
while (true)
{
// Get request from client
ProxyMessage clientRequest = proxyServer.ReceiveClientMessage();
_clients[clientRequest.ClientEndpoint] = clientRequest.Socket;
//ColorizedWriteLine($"REQUEST from {clientRequest.ClientEndpoint}", ConsoleColor.Green);
// Pick the most available server
IPEndPoint handlingServer;
lock (_loadBalancer)
{
//Console.WriteLine("Picking Web Server...");
handlingServer = _loadBalancer.PickMostAvailableCarrier();
//Console.WriteLine($"Picked {handlingServer}");
}
try
{
// Pass the request of the client to the server
//Console.WriteLine($"Passing Client Request to {handlingServer}");
proxyServer.PassClientMessage(clientRequest, handlingServer);
// Add the load to the handling server
_loadBalancer.AddLoad(handlingServer);
}
catch // There's a problem with the web server
{
// Send the client an error message
byte[] problemResponseData = Encoding.ASCII.GetBytes("HTTP/1.1 500 Internal Server Error");
var clientEP = clientRequest.ClientEndpoint;
proxyServer.PassResponse(new ProxyMessage(clientEP, null, problemResponseData), clientRequest.Socket);
// Remove the load from the handling server
_loadBalancer.RemoveLoad(handlingServer);
// Notify in the console that the web server has a problem
ColorizedWriteLine($"Web Server {handlingServer} has a problem! (2)", ConsoleColor.Red);
continue;
}
// Queue a thread for handling the request
ThreadPool.QueueUserWorkItem((obj) =>
{
try
{
// Get the response for the client form the server
ProxyMessage serverResponse = proxyServer.ReceiveResponse();
// Pass the response to the client
proxyServer.PassResponse(serverResponse, _clients[serverResponse.ClientEndpoint]);
_clients.Remove(serverResponse.ClientEndpoint);
//ColorizedWriteLine($"RESPONSE to {clientRequest.ClientEndpoint}", ConsoleColor.Blue);
}
catch (Exception e)
{
// Send the client an error message
byte[] problemResponseData = Encoding.ASCII.GetBytes("HTTP/1.1 500 Internal Server Error");
var clientEP = clientRequest.ClientEndpoint;
proxyServer.PassResponse(new ProxyMessage(clientEP, null, problemResponseData), clientRequest.Socket);
// Notify in the console that the web server has a problem
ColorizedWriteLine($"Web Server {handlingServer} has a problem!\n", ConsoleColor.Red);
}
// Remove the load from the handling server
_loadBalancer.RemoveLoad(handlingServer);
});
}
}
