// Validate the response headers and return the sub-protocol.
private string ValidateResponse(HttpWebRequest request, HttpWebResponse response)
{
// 101
if (response.StatusCode != HttpStatusCode.SwitchingProtocols)
{
throw new WebSocketException(SR.GetString(SR.net_WebSockets_Connect101Expected,
(int)response.StatusCode));
}
// Upgrade: websocket
string upgradeHeader = response.Headers[HttpKnownHeaderNames.Upgrade];
if (!string.Equals(upgradeHeader, WebSocketHelpers.WebSocketUpgradeToken,
StringComparison.OrdinalIgnoreCase))
{
throw new WebSocketException(SR.GetString(SR.net_WebSockets_InvalidResponseHeader,
HttpKnownHeaderNames.Upgrade, upgradeHeader));
}
// Connection: Upgrade
string connectionHeader = response.Headers[HttpKnownHeaderNames.Connection];
if (!string.Equals(connectionHeader, HttpKnownHeaderNames.Upgrade,
StringComparison.OrdinalIgnoreCase))
{
throw new WebSocketException(SR.GetString(SR.net_WebSockets_InvalidResponseHeader,
HttpKnownHeaderNames.Connection, connectionHeader));
}
// Sec-WebSocket-Accept derived from request Sec-WebSocket-Key
string websocketAcceptHeader = response.Headers[HttpKnownHeaderNames.SecWebSocketAccept];
string expectedAcceptHeader = WebSocketHelpers.GetSecWebSocketAcceptString(
request.Headers[HttpKnownHeaderNames.SecWebSocketKey]);
if (!string.Equals(websocketAcceptHeader, expectedAcceptHeader, StringComparison.OrdinalIgnoreCase))
{
throw new WebSocketException(SR.GetString(SR.net_WebSockets_InvalidResponseHeader,
HttpKnownHeaderNames.SecWebSocketAccept, websocketAcceptHeader));
}
// Sec-WebSocket-Protocol matches one from request
// A missing header is ok. It's also ok if the client didn't specify any.
string subProtocol = response.Headers[HttpKnownHeaderNames.SecWebSocketProtocol];
if (!string.IsNullOrWhiteSpace(subProtocol) && options.RequestedSubProtocols.Count > 0)
{
bool foundMatch = false;
foreach (string requestedSubProtocol in options.RequestedSubProtocols)
{
if (string.Equals(requestedSubProtocol, subProtocol, StringComparison.OrdinalIgnoreCase))
{
foundMatch = true;
break;
}
}
if (!foundMatch)
{
throw new WebSocketException(SR.GetString(SR.net_WebSockets_AcceptUnsupportedProtocol,
string.Join(", ", options.RequestedSubProtocols), subProtocol));
}
}
return(string.IsNullOrWhiteSpace(subProtocol) ? null : subProtocol); // May be null or valid.
}
private async Task ConnectAsyncCore(Uri uri, CancellationToken cancellationToken)
{
HttpWebResponse response = null;
CancellationTokenRegistration connectCancellation = new CancellationTokenRegistration();
// Any errors from here on out are fatal and this instance will be disposed.
try
{
HttpWebRequest request = CreateAndConfigureRequest(uri);
if (Logging.On)
{
Logging.Associate(Logging.WebSockets, this, request);
}
connectCancellation = cancellationToken.Register(AbortRequest, request, false);
response = await request.GetResponseAsync().SuppressContextFlow() as HttpWebResponse;
Contract.Assert(response != null, "Not an HttpWebResponse");
this.RequestId = response.Headers.Get("X-RequestId");
if (Logging.On)
{
Logging.Associate(Logging.WebSockets, this, response);
}
string subprotocol = ValidateResponse(request, response);
innerWebSocket = WebSocket.CreateClientWebSocket(response.GetResponseStream(), subprotocol,
options.ReceiveBufferSize, options.SendBufferSize, options.KeepAliveInterval, false,
options.GetOrCreateBuffer());
if (Logging.On)
{
Logging.Associate(Logging.WebSockets, this, innerWebSocket);
}
// Change internal state to 'connected' to enable the other methods
if (Interlocked.CompareExchange(ref state, connected, connecting) != connecting)
{
// Aborted/Disposed during connect.
throw new ObjectDisposedException(GetType().FullName);
}
}
catch (WebException ex)
{
ConnectExceptionCleanup(response);
WebSocketException wex = new WebSocketException(SR.GetString(SR.net_webstatus_ConnectFailure), ex);
if (Logging.On)
{
Logging.Exception(Logging.WebSockets, this, "ConnectAsync", wex);
}
throw wex;
}
catch (Exception ex)
{
ConnectExceptionCleanup(response);
if (Logging.On)
{
Logging.Exception(Logging.WebSockets, this, "ConnectAsync", ex);
}
throw;
}
finally
{
// We successfully connected (or failed trying), disengage from this token.
// Otherwise any timeout/cancellation would apply to the full session.
// In the failure case we need to release the reference to HWR.
connectCancellation.Dispose();
}
}