grpcwebproxy incompatibility with aspnet core

[FabianTerhorst]

Versions of relevant software used
latest grpcwebproxy binary for osx.

What happened
the http request to the grpc server contains a invalid connection header field.

What you expected to happen
A valid http/2 request.

How to reproduce it (as minimally and precisely as possible):
Start a aspnet core grpc server (0.1.20).
Start the proxy.
Send grpc request from browser to the proxy.
Server will throw a exception:

Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2ConnectionErrorException: HTTP/2 connection error (PROTOCOL_ERROR): Request headers contain connection-specific header field.
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2Connection.ValidateHeader(Span`1 name, Span`1 value)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2Connection.OnHeader(Span`1 name, Span`1 value)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack.HPackDecoder.ProcessHeaderValue(IHttpHeadersHandler handler)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack.HPackDecoder.OnByte(Byte b, IHttpHeadersHandler handler)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack.HPackDecoder.Decode(ReadOnlySequence`1 data, Boolean endHeaders, IHttpHeadersHandler handler)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2Connection.DecodeHeadersAsync(Boolean endHeaders, ReadOnlySequence`1 payload)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2Connection.ProcessHeadersFrameAsync[TContext](IHttpApplication`1 application, ReadOnlySequence`1 payload)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2Connection.ProcessFrameAsync[TContext](IHttpApplication`1 application, ReadOnlySequence`1 payload)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.Http2Connection.ProcessRequestsAsync[TContext](IHttpApplication`1 application)

Line where the exception is throwed: https://github.com/aspnet/AspNetCore/blob/master/src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.cs#L1165

Environment:

• OS 0sx 10.14.4:

[johanbrandhorst]

The grpcwebproxy just uses the Go gRPC stack to make downstream requests. Can you reproduce this issue with a Go gRPC client?

[johanbrandhorst]

For the curious: it seems connection is a reserved header, and te too, but only if it doesn't appear in a trailer.

[FabianTerhorst]

No i can't reproduce it with the go grpc client. I have switched to envoy now which is working

[johanbrandhorst]

Interesting. Are you setting the connection header in the requests from the front-end? I don't think the proxy sets it.

[FabianTerhorst]

I only used the generated service method without specifying any options and without any meta data.

[FabianTerhorst]

I was able to resolve it by using port 8443 with https instead of 8080 with http on localhost.

[johanbrandhorst]

Closing this as it is unlikely to be a bug in the proxy