/// <summary>
/// Sends the handshake asynchronous.
/// </summary>
/// <param name="handshake">The handshake.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns></returns>
public async Task <WebSocketResponseHandshake> SendHandshakeAsync(WebSocketRequestHandshake handshake, CancellationToken cancellationToken)
{
var oldState = Interlocked.CompareExchange(ref _state, WebSocketState.Opening, WebSocketState.Connected);
if (oldState != WebSocketState.Connected)
{
throw new InvalidOperationException(ErrorMessages.InvalidState + _state);
}
var data = handshake.ToString();
await this.SendAsync(data, Encoding.UTF8, cancellationToken);
var responseHeaders = new List <string>();
var line = await _tcp.ReadLineAsync(cancellationToken);
while (!String.IsNullOrEmpty(line))
{
responseHeaders.Add(line);
line = await _tcp.ReadLineAsync(cancellationToken);
}
var response = WebSocketResponseHandshake.Parse(responseHeaders);
if (response.StatusCode != HttpStatusCode.SwitchingProtocols)
{
var versions = response.SecWebSocketVersion;
if (versions != null && !versions.Intersect(Consts.SupportedClientVersions).Any())
{
throw new WebSocketException(WebSocketErrorCode.HandshakeVersionNotSupported);
}
throw new WebSocketException(WebSocketErrorCode.HandshakeInvalidStatusCode);
}
var challenge = Encoding.UTF8.GetBytes(handshake.SecWebSocketKey + Consts.ServerGuid);
var hash = Sha1Digest.ComputeHash(challenge);
var calculatedAccept = Convert.ToBase64String(hash);
if (response.SecWebSocketAccept != calculatedAccept)
{
throw new WebSocketException(WebSocketErrorCode.HandshakeInvalidSecWebSocketAccept);
}
response.RequestMessage = handshake;
Interlocked.Exchange(ref _state, WebSocketState.Open);
return(response);
}