//Asynchronous request handler.
public async Task WebSocketRequestHandler(WebSocketContext webSocketContext)
{
//Gets the current WebSocket object.
WebSocket webSocket = webSocketContext.WebSocket;
//check the integrity of the connection
/*We define a certain constant which will represent
* size of received data. It is established by us and
* we can set any value. We know that in this case the size of the sent
* data is very small.
*/
const int maxMessageSize = 512;
//Buffer for received bits.
var receivedDataBuffer = new ArraySegment <Byte>(new Byte[maxMessageSize]);
var cancellationToken = new CancellationToken();
//Checks WebSocket state.
while (webSocket.State == WebSocketState.Open)
{
//Reads data.
WebSocketReceiveResult webSocketReceiveResult =
await webSocket.ReceiveAsync(receivedDataBuffer, cancellationToken);
bool errorDetected = false;
//If input frame is cancelation frame, send close command.
if (webSocketReceiveResult.MessageType == WebSocketMessageType.Close)
{
await webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure,
String.Empty, cancellationToken);
}
else
{
byte[] payloadData = receivedDataBuffer.Array.ToList().GetRange(0, webSocketReceiveResult.Count).ToArray();
WebsocketDataPackage package = GetPackage(ref payloadData);
string clientWsToken = GetConnectionCredential(package.clientId).HashedKey;
if (!CheckDataIntegrity(package.Data, package.HashedKey, clientWsToken))
{
errorDetected = true;
byte[] serializedData = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(package.Data) + clientWsToken);
string receivedHashedKey = Convert.ToBase64String(SHA1.Create().ComputeHash(serializedData));
string message =
String.Format("Corrupted package: SHA1 received: {0} SHA1 expected: {1}", receivedHashedKey, package.HashedKey);
Byte[] bytesToSend = System.Text.Encoding.UTF8.GetBytes(message);
//Sends data back.
await webSocket.SendAsync(new ArraySegment <byte>(bytesToSend),
WebSocketMessageType.Text, true, cancellationToken);
}
if (!errorDetected)
{
ConnectionCredentials cc = GetConnectionCredential(package.clientId);
if (!cc.ConnectionSet)
{
Connection conn = new Connection(cc, webSocket);
BindConnection(GetConnectionCredential(package.clientId), conn);
}
var newString =
String.Format("Hello, package with hashed key: " + package.HashedKey + " validated! Time {0}", DateTime.Now.ToString());
Byte[] bytes = System.Text.Encoding.UTF8.GetBytes(newString);
//Sends data back.
await webSocket.SendAsync(new ArraySegment <byte>(bytes),
WebSocketMessageType.Text, true, cancellationToken);
}
}
}
}