private async ValueTask <ForwarderError> HandleUpgradedResponse(HttpContext context, HttpResponseMessage destinationResponse,
ActivityCancellationTokenSource activityCancellationSource)
{
ForwarderTelemetry.Log.ForwarderStage(ForwarderStage.ResponseUpgrade);
// SocketHttpHandler and similar transports always provide an HttpContent object, even if it's empty.
// Note as of 5.0 HttpResponse.Content never returns null.
// https://github.com/dotnet/runtime/blame/8fc68f626a11d646109a758cb0fc70a0aa7826f1/src/libraries/System.Net.Http/src/System/Net/Http/HttpResponseMessage.cs#L46
if (destinationResponse.Content == null)
{
throw new InvalidOperationException("A response content is required for upgrades.");
}
// :: Step 7-A-1: Upgrade the client channel. This will also send response headers.
var upgradeFeature = context.Features.Get <IHttpUpgradeFeature>();
if (upgradeFeature == null)
{
var ex = new InvalidOperationException("Invalid 101 response when upgrades aren't supported.");
destinationResponse.Dispose();
context.Response.StatusCode = StatusCodes.Status502BadGateway;
ReportProxyError(context, ForwarderError.UpgradeResponseDestination, ex);
return(ForwarderError.UpgradeResponseDestination);
}
RestoreUpgradeHeaders(context, destinationResponse);
Stream upgradeResult;
try
{
upgradeResult = await upgradeFeature.UpgradeAsync();
}
catch (Exception ex)
{
destinationResponse.Dispose();
ReportProxyError(context, ForwarderError.UpgradeResponseClient, ex);
return(ForwarderError.UpgradeResponseClient);
}
using var clientStream = upgradeResult;
// :: Step 7-A-2: Copy duplex streams
using var destinationStream = await destinationResponse.Content.ReadAsStreamAsync();
var requestTask = StreamCopier.CopyAsync(isRequest: true, clientStream, destinationStream, StreamCopier.UnknownLength, _clock, activityCancellationSource, activityCancellationSource.Token).AsTask();
var responseTask = StreamCopier.CopyAsync(isRequest: false, destinationStream, clientStream, StreamCopier.UnknownLength, _clock, activityCancellationSource, activityCancellationSource.Token).AsTask();
// Make sure we report the first failure.
var firstTask = await Task.WhenAny(requestTask, responseTask);
var requestFinishedFirst = firstTask == requestTask;
var secondTask = requestFinishedFirst ? responseTask : requestTask;
ForwarderError error;
var(firstResult, firstException) = await firstTask;
if (firstResult != StreamCopyResult.Success)
{
error = ReportResult(context, requestFinishedFirst, firstResult, firstException);
// Cancel the other direction
activityCancellationSource.Cancel();
// Wait for this to finish before exiting so the resources get cleaned up properly.
await secondTask;
}
else
{
var(secondResult, secondException) = await secondTask;
if (secondResult != StreamCopyResult.Success)
{
error = ReportResult(context, !requestFinishedFirst, secondResult, secondException !);
}
else
{
error = ForwarderError.None;
}
}
return(error);
ForwarderError ReportResult(HttpContext context, bool reqeuest, StreamCopyResult result, Exception exception)
{
var error = result switch
{
StreamCopyResult.InputError => reqeuest ? ForwarderError.UpgradeRequestClient : ForwarderError.UpgradeResponseDestination,
StreamCopyResult.OutputError => reqeuest ? ForwarderError.UpgradeRequestDestination : ForwarderError.UpgradeResponseClient,
StreamCopyResult.Canceled => reqeuest ? ForwarderError.UpgradeRequestCanceled : ForwarderError.UpgradeResponseCanceled,
_ => throw new NotImplementedException(result.ToString()),
};
ReportProxyError(context, error, exception);
return(error);
}
}