public async Task Invoke(HttpContext httpContext)
{
var originalResponseBody = httpContext.Response.Body;
// no-op if buffering is already available.
if (originalResponseBody.CanSeek)
{
await _next(httpContext);
return;
}
var originalBufferingFeature = httpContext.Features.Get <IHttpBufferingFeature>();
var originalSendFileFeature = httpContext.Features.Get <IHttpSendFileFeature>();
try
{
// Shim the response stream
var bufferStream = new BufferingWriteStream(originalResponseBody);
httpContext.Response.Body = bufferStream;
httpContext.Features.Set <IHttpBufferingFeature>(new HttpBufferingFeature(bufferStream, originalBufferingFeature));
if (originalSendFileFeature != null)
{
httpContext.Features.Set <IHttpSendFileFeature>(new SendFileFeatureWrapper(originalSendFileFeature, bufferStream));
}
await _next(httpContext);
// If we're still buffered, set the content-length header and flush the buffer.
// Only if the content-length header is not already set, and some content was buffered.
if (!httpContext.Response.HasStarted && bufferStream.CanSeek && bufferStream.Length > 0)
{
if (!httpContext.Response.ContentLength.HasValue)
{
httpContext.Response.Headers["X-Decompressed-Content-Length"] = bufferStream.Length.ToString();
}
await bufferStream.FlushAsync();
}
}
finally
{
// undo everything
httpContext.Features.Set(originalBufferingFeature);
httpContext.Features.Set(originalSendFileFeature);
httpContext.Response.Body = originalResponseBody;
}
}
public SendFileFeatureWrapper(IHttpSendFileFeature originalSendFileFeature, BufferingWriteStream bufferStream)
{
_originalSendFileFeature = originalSendFileFeature;
_bufferStream = bufferStream;
}
internal HttpBufferingFeature(BufferingWriteStream buffer, IHttpBufferingFeature innerFeature)
{
_buffer = buffer;
_innerFeature = innerFeature;
}