/// <summary>
/// Handles the main functionality and logica of the application
/// </summary>
private void Handler()
{
bool recvRequest = true;
string EOL = "\r\n";
string requestPayload = "";
string requestTempLine = "";
List <string> requestLines = new List <string>();
byte[] requestBuffer = new byte[1];
byte[] responseBuffer = new byte[1];
requestLines.Clear();
// Try to get the request headers from the client
try
{
//State 0: Handle Request from Client
while (recvRequest)
{
this._clientSocket.Receive(requestBuffer);
string fromByte = ASCIIEncoding.ASCII.GetString(requestBuffer);
requestPayload += fromByte;
requestTempLine += fromByte;
// Format the string headers to a list of headers
if (requestTempLine.EndsWith(EOL))
{
requestLines.Add(requestTempLine.Trim());
requestTempLine = "";
}
// If the request ends with double end of line it has received the headers
if (requestPayload.EndsWith(EOL + EOL))
{
recvRequest = false;
}
}
string cookie = null;
string session = null;
string url = null;
requestPayload = "";
// Loop through all the HTTP Headers
foreach (string line in requestLines)
{
// Remove Accept-Encoding to display the plain HTML
bool addLines = !line.Contains("Accept-Encoding");
// If the line contains a cookie we will check what algorithm is active and react based on that
if (line.Contains("Cookie"))
{
switch (Algoritme.Get())
{
case "Cookie Based":
cookie = line.Split('=')[1];
break;
case "Session Based":
session = line.Split('=')[1];
break;
}
}
// Add the HTTP Header to the requestPayload
if (addLines)
{
requestPayload += line;
requestPayload += EOL;
}
}
// Determine what server we need to connect to
var selectedServer = _server.GetConnectionInfo(cookie, session);
// Try to connect to the chosen server
try
{
TcpClient client = new TcpClient(selectedServer[0], Int32.Parse(selectedServer[1]));
var stream = client.GetStream();
// Write the request to the server
stream.Write(ASCIIEncoding.ASCII.GetBytes(requestPayload), 0, ASCIIEncoding.ASCII.GetBytes(requestPayload).Length);
// If the algorithm is cookie based we need to add a cookie to the response headers
if (Algoritme.Get() == "Cookie Based")
{
string response = null;
var contentLengthIsAvailable = false;
var headersInThePocket = false;
int contentLength = 0;
StringBuilder responseBytes = null;
var i = 0;
while (true)
{
// Read all the bytes from the server
stream.Read(responseBuffer, 0, responseBuffer.Length);
// Convert these bytes to a string and add these to the response string
response += Encoding.ASCII.GetString(responseBuffer);
// Check if all the headers are received
if (response.EndsWith(EOL + EOL))
{
// Add a "Set-Cookie" header to the response headers
response = response.Split(new[] { EOL + EOL }, StringSplitOptions.None)[0];
var connectionCookie = selectedServer[0] + ":" + selectedServer[1];
response += EOL + "Set-Cookie: fixed-server=" + Algoritme.CalculateMD5Hash(connectionCookie) + EOL + EOL;
var headers = response.Split(':');
// Determine the Content-Length for further reading
var contentLengthAvailable = false;
foreach (var header in headers)
{
if (contentLengthAvailable)
{
contentLength = int.Parse(header.Split('\r')[0]);
contentLengthAvailable = false;
}
if (header.EndsWith("Content-Length"))
{
contentLengthAvailable = true;
}
}
responseBytes = new StringBuilder(response);
headersInThePocket = true;
}
// Read the body when the headers are in the pocket
if (headersInThePocket)
{
if (contentLength == 0)
{
// If the response has nog content-length header we will set it on a default
contentLength = 2000;
}
if (i < contentLength)
{
// As long as the body has not been received we will append the body to our responseBytes
responseBytes.Append(Encoding.ASCII.GetString(responseBuffer));
i++;
}
else
{
var charResponse = responseBytes.ToString().ToCharArray(0, responseBytes.Length);
byte[] test = Encoding.ASCII.GetBytes(charResponse);
// Sent the response to the clientSocket
_clientSocket.Send(test);
// Break out of the while loop as we do not need to receive anymore bytes
break;
}
}
}
}
// If Algorithm "Cookie-Based" has not been selected. We will send everything straight through
else
{
while (stream.Read(responseBuffer, 0, responseBuffer.Length) != 0)
{
this._clientSocket.Send(responseBuffer);
}
}
// Remove the server from the request for the load Algorithm
foreach (var serverRequest in Algoritme.requestPerServer)
{
if (serverRequest[0] == selectedServer[0])
{
Algoritme.requestPerServer.Remove(serverRequest);
}
}
client.Close();
stream.Dispose();
}
// When the recommended server cannot be contacted
catch (SocketException e)
{
Console.Write("Server has fallen", e);
Handler();
}
// Cleanup our socket
this._clientSocket.Disconnect(false);
this._clientSocket.Dispose();
}
catch (Exception e)
{
Console.WriteLine("Error Occured: " + e.Message);
}
}
/// <summary>
/// Determine what server the server class has to connect to.
/// It takes the algorithm and based on that it will choose the server
/// </summary>
/// <param name="cookie">Cookie if there is any otherwise it is null</param>
/// <param name="session">Session if there is any otherwise it is null</param>
/// <returns>Server object with connect information</returns>
public string[] GetConnectionInfo(string cookie, string session)
{
int serverChosen = 0;
switch (Algoritme.Get())
{
case "Random":
Random rnd = new Random();
serverChosen = rnd.Next(0, servers.Count);
break;
case "Round Robin":
serverChosen = Algoritme.roundRobinPos;
if (Algoritme.roundRobinPos != servers.Count - 1)
{
Algoritme.roundRobinPos++;
}
else
{
Algoritme.roundRobinPos = 0;
}
break;
case "Load":
// Chooses the server with the less Load. What is based on the current amount of connections to a server.
serverChosen = 0;
List <int> requestsServers = new List <int>();
foreach (var serverRequest in Algoritme.requestPerServer)
{
requestsServers.Add(Int32.Parse(serverRequest[1]));
}
var i = 0;
foreach (var requestsServer in requestsServers)
{
if (requestsServer == requestsServers.Min())
{
serverChosen = i;
}
i++;
}
break;
case "Cookie Based":
var j = 0;
foreach (var server in servers)
{
if (server.ToString().Split('/')[2] == cookie)
{
serverChosen = j;
}
j++;
}
break;
case "Session Based":
var sessions = Algoritme.sessionsPerServer;
// If there is no session set yet it will choose a server based on Round Robin
if (session == null)
{
serverChosen = Algoritme.roundRobinPos;
if (Algoritme.roundRobinPos != servers.Count - 1)
{
Algoritme.roundRobinPos++;
}
else
{
Algoritme.roundRobinPos = 0;
}
}
// There is a session
else
{
// Check if the session is already stored in our list of stored sessions
var isAlreadyStored = false;
object selectedServer = null;
foreach (var stringse in Algoritme.sessionsPerServer)
{
if (session == stringse[0])
{
isAlreadyStored = true;
selectedServer = stringse[1];
}
}
if (isAlreadyStored)
{
// The session is already stored
var l = 0;
foreach (var server in servers)
{
if (server == selectedServer)
{
serverChosen = l;
}
l++;
}
}
else
{
// Session is not stored yet
// Add new session id to the local storage
var k = 0;
string[] sessionPerServer = null;
if (Algoritme.roundRobinPos != 0)
{
Algoritme.roundRobinPos--;
}
else
{
Algoritme.roundRobinPos = servers.Count - 1;
}
foreach (var server in servers)
{
if (k == Algoritme.roundRobinPos)
{
sessionPerServer = new string[] { session, server.ToString() };
}
k++;
}
serverChosen = Algoritme.roundRobinPos;
Algoritme.sessionsPerServer.Add(sessionPerServer);
}
}
break;
}
// Keep track of the requests for health monitoring
HealthMonitor.addConnection(serverChosen);
// Return the connectInfo to the server class
var connectInfo = GetHostAndPort(servers[serverChosen] as string);
return(connectInfo);
}
