public async Task DestinationThrows_Reported(bool isRequest)
{
var events = TestEventListener.Collect();
const int SourceSize = 10;
const int BytesPerRead = 3;
var clock = new ManualClock();
var sourceWaitTime = TimeSpan.FromMilliseconds(12345);
var destinationWaitTime = TimeSpan.FromMilliseconds(42);
var source = new SlowStream(new MemoryStream(new byte[SourceSize]), clock, sourceWaitTime)
{
MaxBytesPerRead = BytesPerRead
};
var destination = new SlowStream(new ThrowStream(), clock, destinationWaitTime);
using var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
var(result, error) = await StreamCopier.CopyAsync(isRequest, source, destination, SourceSize, clock, cts, cts.Token);
Assert.Equal(StreamCopyResult.OutputError, result);
Assert.IsAssignableFrom <IOException>(error);
AssertContentTransferred(events, isRequest,
contentLength: BytesPerRead,
iops: 1,
firstReadTime: sourceWaitTime,
readTime: sourceWaitTime,
writeTime: destinationWaitTime);
}
public async Task SerializeToStreamAsync_RespectsContentCancellation()
{
var tcs = new TaskCompletionSource <byte>(TaskCreationOptions.RunContinuationsAsynchronously);
var source = new ReadDelegatingStream(new MemoryStream(), async(buffer, cancellation) =>
{
if (buffer.Length == 0)
{
return(0);
}
Assert.False(cancellation.IsCancellationRequested);
await tcs.Task;
Assert.True(cancellation.IsCancellationRequested);
return(0);
});
using var contentCts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
var sut = CreateContent(source, contentCancellation: contentCts);
var copyToTask = sut.CopyToWithCancellationAsync(new MemoryStream());
contentCts.Cancel();
tcs.SetResult(0);
await copyToTask;
}
public async Task SlowStreams_TelemetryReportsCorrectTime(bool isRequest)
{
var events = TestEventListener.Collect();
const int SourceSize = 3;
var sourceBytes = new byte[SourceSize];
var source = new MemoryStream(sourceBytes);
var destination = new MemoryStream();
var clock = new ManualClock();
var sourceWaitTime = TimeSpan.FromMilliseconds(12345);
var destinationWaitTime = TimeSpan.FromMilliseconds(42);
using var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
await StreamCopier.CopyAsync(
isRequest,
new SlowStream(source, clock, sourceWaitTime),
new SlowStream(destination, clock, destinationWaitTime),
SourceSize,
clock,
cts,
cts.Token);
Assert.Equal(sourceBytes, destination.ToArray());
AssertContentTransferred(events, isRequest, SourceSize,
iops: SourceSize + 1,
firstReadTime: sourceWaitTime,
readTime: (SourceSize + 1) * sourceWaitTime,
writeTime: SourceSize * destinationWaitTime);
}
private static StreamCopyHttpContent CreateContent(Stream source = null, bool autoFlushHttpClientOutgoingStream = false, IClock clock = null, ActivityCancellationTokenSource contentCancellation = null)
{
source ??= new MemoryStream();
clock ??= new Clock();
contentCancellation ??= ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
return(new StreamCopyHttpContent(source, autoFlushHttpClientOutgoingStream, clock, contentCancellation));
}
private static StreamCopyHttpContent CreateContent(HttpRequest request = null, bool autoFlushHttpClientOutgoingStream = false, IClock clock = null, ActivityCancellationTokenSource contentCancellation = null)
{
request ??= new DefaultHttpContext().Request;
clock ??= new Clock();
contentCancellation ??= ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
return(new StreamCopyHttpContent(request, autoFlushHttpClientOutgoingStream, clock, contentCancellation));
}
public void ActivityCancellationTokenSource_RespectsLinkedToken()
{
var linkedCts = new CancellationTokenSource();
var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), linkedCts.Token);
linkedCts.Cancel();
Assert.True(cts.IsCancellationRequested);
}
public void ActivityCancellationTokenSource_DoesNotPoolsCanceledSources()
{
var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
cts.Cancel();
var cts2 = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
Assert.NotSame(cts, cts2);
}
public void ActivityCancellationTokenSource_ClearsRegistrations()
{
var linkedCts = new CancellationTokenSource();
var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), linkedCts.Token);
cts.Return();
linkedCts.Cancel();
Assert.False(cts.IsCancellationRequested);
}
public async Task ActivityCancellationTokenSource_RespectsTimeout()
{
var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromMilliseconds(1), CancellationToken.None);
for (var i = 0; i < 1000; i++)
{
if (cts.IsCancellationRequested)
{
return;
}
await Task.Delay(1);
}
Assert.True(false, "Cts was not canceled");
}
public async Task CopyAsync_Works(bool isRequest)
{
var events = TestEventListener.Collect();
const int SourceSize = (128 * 1024) - 3;
var sourceBytes = Enumerable.Range(0, SourceSize).Select(i => (byte)(i % 256)).ToArray();
var source = new MemoryStream(sourceBytes);
var destination = new MemoryStream();
using var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
await StreamCopier.CopyAsync(isRequest, source, destination, SourceSize, new Clock(), cts, cts.Token);
Assert.False(cts.Token.IsCancellationRequested);
Assert.Equal(sourceBytes, destination.ToArray());
AssertContentTransferred(events, isRequest, SourceSize);
}
public void ActivityCancellationTokenSource_PoolsSources()
{
// This test can run in parallel with others making use of ActivityCancellationTokenSource
// A different thread could have already added/removed a source from the queue
for (var i = 0; i < 1000; i++)
{
var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
cts.Return();
var cts2 = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
cts2.Return();
if (ReferenceEquals(cts, cts2))
{
return;
}
}
Assert.True(false, "CancellationTokenSources were not pooled");
}
public async Task Cancelled_Reported(bool isRequest)
{
var events = TestEventListener.Collect();
var source = new MemoryStream(new byte[10]);
var destination = new MemoryStream();
using var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
cts.Cancel();
var(result, error) = await StreamCopier.CopyAsync(isRequest, source, destination, StreamCopier.UnknownLength, new ManualClock(), cts, cts.Token);
Assert.Equal(StreamCopyResult.Canceled, result);
Assert.IsAssignableFrom <OperationCanceledException>(error);
AssertContentTransferred(events, isRequest,
contentLength: 0,
iops: 1,
firstReadTime: TimeSpan.Zero,
readTime: TimeSpan.Zero,
writeTime: TimeSpan.Zero);
}
public async Task SourceThrows_Reported(bool isRequest)
{
var events = TestEventListener.Collect();
var clock = new ManualClock();
var sourceWaitTime = TimeSpan.FromMilliseconds(12345);
var source = new SlowStream(new ThrowStream(), clock, sourceWaitTime);
var destination = new MemoryStream();
using var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
var(result, error) = await StreamCopier.CopyAsync(isRequest, source, destination, StreamCopier.UnknownLength, clock, cts, cts.Token);
Assert.Equal(StreamCopyResult.InputError, result);
Assert.IsAssignableFrom <IOException>(error);
AssertContentTransferred(events, isRequest,
contentLength: 0,
iops: 1,
firstReadTime: sourceWaitTime,
readTime: sourceWaitTime,
writeTime: TimeSpan.Zero);
}
/// <summary>
/// Proxies the incoming request to the destination server, and the response back to the client.
/// </summary>
/// <remarks>
/// In what follows, as well as throughout in Reverse Proxy, we consider
/// the following picture as illustrative of the Proxy.
/// <code>
/// +-------------------+
/// | Destination +
/// +-------------------+
/// ▲ |
/// (b) | | (c)
/// | ▼
/// +-------------------+
/// | Proxy +
/// +-------------------+
/// ▲ |
/// (a) | | (d)
/// | ▼
/// +-------------------+
/// | Client +
/// +-------------------+
/// </code>
///
/// (a) and (b) show the *request* path, going from the client to the target.
/// (c) and (d) show the *response* path, going from the destination back to the client.
///
/// Normal proxying comprises the following steps:
/// (0) Disable ASP .NET Core limits for streaming requests
/// (1) Create outgoing HttpRequestMessage
/// (2) Setup copy of request body (background) Client --► Proxy --► Destination
/// (3) Copy request headers Client --► Proxy --► Destination
/// (4) Send the outgoing request using HttpMessageInvoker Client --► Proxy --► Destination
/// (5) Copy response status line Client ◄-- Proxy ◄-- Destination
/// (6) Copy response headers Client ◄-- Proxy ◄-- Destination
/// (7-A) Check for a 101 upgrade response, this takes care of WebSockets as well as any other upgradeable protocol.
/// (7-A-1) Upgrade client channel Client ◄--- Proxy ◄--- Destination
/// (7-A-2) Copy duplex streams and return Client ◄--► Proxy ◄--► Destination
/// (7-B) Copy (normal) response body Client ◄-- Proxy ◄-- Destination
/// (8) Copy response trailer headers and finish response Client ◄-- Proxy ◄-- Destination
/// (9) Wait for completion of step 2: copying request body Client --► Proxy --► Destination
///
/// ASP .NET Core (Kestrel) will finally send response trailers (if any)
/// after we complete the steps above and relinquish control.
/// </remarks>
public async ValueTask <ForwarderError> SendAsync(
HttpContext context,
string destinationPrefix,
HttpMessageInvoker httpClient,
ForwarderRequestConfig requestConfig,
HttpTransformer transformer)
{
_ = context ?? throw new ArgumentNullException(nameof(context));
_ = destinationPrefix ?? throw new ArgumentNullException(nameof(destinationPrefix));
_ = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
_ = requestConfig ?? throw new ArgumentNullException(nameof(requestConfig));
_ = transformer ?? throw new ArgumentNullException(nameof(transformer));
// HttpClient overload for SendAsync changes response behavior to fully buffered which impacts performance
// See discussion in https://github.com/microsoft/reverse-proxy/issues/458
if (httpClient is HttpClient)
{
throw new ArgumentException($"The http client must be of type HttpMessageInvoker, not HttpClient", nameof(httpClient));
}
ForwarderTelemetry.Log.ForwarderStart(destinationPrefix);
var activityCancellationSource = ActivityCancellationTokenSource.Rent(requestConfig?.ActivityTimeout ?? DefaultTimeout, context.RequestAborted);
try
{
var isClientHttp2 = ProtocolHelper.IsHttp2(context.Request.Protocol);
// NOTE: We heuristically assume gRPC-looking requests may require streaming semantics.
// See https://github.com/microsoft/reverse-proxy/issues/118 for design discussion.
var isStreamingRequest = isClientHttp2 && ProtocolHelper.IsGrpcContentType(context.Request.ContentType);
// :: Step 1-3: Create outgoing HttpRequestMessage
var(destinationRequest, requestContent) = await CreateRequestMessageAsync(
context, destinationPrefix, transformer, requestConfig, isStreamingRequest, activityCancellationSource);
// :: Step 4: Send the outgoing request using HttpClient
HttpResponseMessage destinationResponse;
try
{
ForwarderTelemetry.Log.ForwarderStage(ForwarderStage.SendAsyncStart);
destinationResponse = await httpClient.SendAsync(destinationRequest, activityCancellationSource.Token);
ForwarderTelemetry.Log.ForwarderStage(ForwarderStage.SendAsyncStop);
// Reset the timeout since we received the response headers.
activityCancellationSource.ResetTimeout();
}
catch (Exception requestException)
{
return(await HandleRequestFailureAsync(context, requestContent, requestException, transformer, activityCancellationSource));
}
// Detect connection downgrade, which may be problematic for e.g. gRPC.
if (isClientHttp2 && destinationResponse.Version.Major != 2)
{
// TODO: Do something on connection downgrade...
Log.HttpDowngradeDetected(_logger);
}
try
{
// :: Step 5: Copy response status line Client ◄-- Proxy ◄-- Destination
// :: Step 6: Copy response headers Client ◄-- Proxy ◄-- Destination
var copyBody = await CopyResponseStatusAndHeadersAsync(destinationResponse, context, transformer);
if (!copyBody)
{
// The transforms callback decided that the response body should be discarded.
destinationResponse.Dispose();
if (requestContent is not null && requestContent.InProgress)
{
activityCancellationSource.Cancel();
await requestContent.ConsumptionTask;
}
return(ForwarderError.None);
}
}
catch (Exception ex)
{
destinationResponse.Dispose();
if (requestContent is not null && requestContent.InProgress)
{
activityCancellationSource.Cancel();
await requestContent.ConsumptionTask;
}
ReportProxyError(context, ForwarderError.ResponseHeaders, ex);
// Clear the response since status code, reason and some headers might have already been copied and we want clean 502 response.
context.Response.Clear();
context.Response.StatusCode = StatusCodes.Status502BadGateway;
return(ForwarderError.ResponseHeaders);
}
// :: Step 7-A: Check for a 101 upgrade response, this takes care of WebSockets as well as any other upgradeable protocol.
if (destinationResponse.StatusCode == HttpStatusCode.SwitchingProtocols)
{
Debug.Assert(requestContent?.Started != true);
return(await HandleUpgradedResponse(context, destinationResponse, activityCancellationSource));
}
// NOTE: it may *seem* wise to call `context.Response.StartAsync()` at this point
// since it looks like we are ready to send back response headers
// (and this might help reduce extra delays while we wait to receive the body from the destination).
// HOWEVER, this would produce the wrong result if it turns out that there is no content
// from the destination -- instead of sending headers and terminating the stream at once,
// we would send headers thinking a body may be coming, and there is none.
// This is problematic on gRPC connections when the destination server encounters an error,
// in which case it immediately returns the response headers and trailing headers, but no content,
// and clients misbehave if the initial headers response does not indicate stream end.
// :: Step 7-B: Copy response body Client ◄-- Proxy ◄-- Destination
var(responseBodyCopyResult, responseBodyException) = await CopyResponseBodyAsync(destinationResponse.Content, context.Response.Body, activityCancellationSource);
if (responseBodyCopyResult != StreamCopyResult.Success)
{
return(await HandleResponseBodyErrorAsync(context, requestContent, responseBodyCopyResult, responseBodyException !, activityCancellationSource));
}
// :: Step 8: Copy response trailer headers and finish response Client ◄-- Proxy ◄-- Destination
await CopyResponseTrailingHeadersAsync(destinationResponse, context, transformer);
if (isStreamingRequest)
{
// NOTE: We must call `CompleteAsync` so that Kestrel will flush all bytes to the client.
// In the case where there was no response body,
// this is also when headers and trailing headers are sent to the client.
// Without this, the client might wait forever waiting for response bytes,
// while we might wait forever waiting for request bytes,
// leading to a stuck connection and no way to make progress.
await context.Response.CompleteAsync();
}
// :: Step 9: Wait for completion of step 2: copying request body Client --► Proxy --► Destination
// NOTE: It is possible for the request body to NOT be copied even when there was an incoming requet body,
// e.g. when the request includes header `Expect: 100-continue` and the destination produced a non-1xx response.
// We must only wait for the request body to complete if it actually started,
// otherwise we run the risk of waiting indefinitely for a task that will never complete.
if (requestContent is not null && requestContent.Started)
{
var(requestBodyCopyResult, requestBodyException) = await requestContent.ConsumptionTask;
if (requestBodyCopyResult != StreamCopyResult.Success)
{
// The response succeeded. If there was a request body error then it was probably because the client or destination decided
// to cancel it. Report as low severity.
var error = requestBodyCopyResult switch
{
StreamCopyResult.InputError => ForwarderError.RequestBodyClient,
StreamCopyResult.OutputError => ForwarderError.RequestBodyDestination,
StreamCopyResult.Canceled => ForwarderError.RequestBodyCanceled,
_ => throw new NotImplementedException(requestBodyCopyResult.ToString())
};
ReportProxyError(context, error, requestBodyException !);
return(error);
}
}
}
finally
{
activityCancellationSource.Return();
ForwarderTelemetry.Log.ForwarderStop(context.Response.StatusCode);
}
return(ForwarderError.None);
}
public async Task LongContentTransfer_TelemetryReportsTransferringEvents(bool isRequest)
{
var events = TestEventListener.Collect();
const int SourceSize = 123;
var sourceBytes = new byte[SourceSize];
var source = new MemoryStream(sourceBytes);
var destination = new MemoryStream();
var clock = new ManualClock();
var sourceWaitTime = TimeSpan.FromMilliseconds(789); // Every second read triggers ContentTransferring
var destinationWaitTime = TimeSpan.FromMilliseconds(42);
const int BytesPerRead = 3;
var contentReads = (int)Math.Ceiling((double)SourceSize / BytesPerRead);
using var cts = ActivityCancellationTokenSource.Rent(TimeSpan.FromSeconds(10), CancellationToken.None);
await StreamCopier.CopyAsync(
isRequest,
new SlowStream(source, clock, sourceWaitTime) { MaxBytesPerRead = BytesPerRead },
new SlowStream(destination, clock, destinationWaitTime),
SourceSize,
clock,
cts,
cts.Token);
Assert.Equal(sourceBytes, destination.ToArray());
AssertContentTransferred(events, isRequest, SourceSize,
iops: contentReads + 1,
firstReadTime: sourceWaitTime,
readTime: (contentReads + 1) * sourceWaitTime,
writeTime: contentReads * destinationWaitTime);
var transferringEvents = events.Where(e => e.EventName == "ContentTransferring").ToArray();
Assert.Equal(contentReads / 2, transferringEvents.Length);
for (var i = 0; i < transferringEvents.Length; i++)
{
var payload = transferringEvents[i].Payload;
Assert.Equal(5, payload.Count);
Assert.Equal(isRequest, (bool)payload[0]);
var contentLength = (long)payload[1];
var iops = (long)payload[2];
Assert.Equal((i + 1) * 2, iops);
if (contentLength % BytesPerRead == 0)
{
Assert.Equal(iops * BytesPerRead, contentLength);
}
else
{
Assert.Equal(transferringEvents.Length - 1, i);
Assert.Equal(SourceSize, contentLength);
}
var readTime = new TimeSpan((long)payload[3]);
Assert.Equal(iops * sourceWaitTime, readTime, new ApproximateTimeSpanComparer());
var writeTime = new TimeSpan((long)payload[4]);
Assert.Equal(iops * destinationWaitTime, writeTime, new ApproximateTimeSpanComparer());
}
}