stream terminated by RST_STREAM with error code: PROTOCOL_ERROR

[restevez-chs]

What version of gRPC are you using?

v1.42.0

What version of Go are you using (go version)?

go version go1.17.2 darwin/amd64

What operating system (Linux, Windows, …) and version?

Mac OS 10.15.7

What did you do?

I have a working API written in Go using grpc and grpc-gateway. When I upgraded to [email protected], I expected the API to continue to work.

• Ran go get -u google.golang.org/[email protected]
• Previous version google.golang.org/grpc v1.41.0

What did you expect to see?

When I upgraded to [email protected], I expected the API to continue to work.

What did you see instead?

I see this error in the response body

stream terminated by RST_STREAM with error code: PROTOCOL_ERROR

With debug enabled, I see this output in the service logs

2021/11/05 17:16:00 ERROR: [transport] transport: http2Server.operateHeaders parsed a :connection header which makes a request malformed as per the HTTP/2 spec

From my research, these are the changes causing breakage:

• https://github.com/grpc/grpc-go/pull/4803/files#r715937171
• https://github.com/dfawley/grpc-go/blame/709d464189ac3cced4a52332bbf147e2beeebf61/internal/transport/http2_server.go#L394
• dfawley@689f7b1

I have been able to confirm with a Postman request that the error goes away -- and my API request is successful -- if the Connection request header is not present.

However, I am unable to quickly resolve with my Ruby-based Cucumber step definitions where I am using HTTPParty for the API requests. I have also tried net/http. Both of these libraries send a default Connection request header, which at the moment I have been unable to remove.

In summary, the stated changes are causing a breakage which is unexpected for a minor version -- the PR feedback indicates there was a concern during the PR review too. I'm new to Go and GRPC, so any extra feedback would be great.

Thank you.

[restevez-chs]

Update: on my side of things, I was able to resolve using the header filter mechanism with the grpc-gateway. Their docs describe the approach.

TL;DR - the header filter is used to remove the Connection header.

I still think the breakage in the minor version is questionable, but after more reading, I understand that the change was made to enforce the rule that the Connection header is not to be used with HTTP/2:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Connection

I look forward to any extra comments and feedback you have. Thank you.

[dfawley]

Correct. This is part of the HTTP/2 spec that we were not following before, so this would be considered a bug fix. Specifically:

https://httpwg.org/specs/rfc7540.html#rfc.section.8.1.2.2

An endpoint MUST NOT generate an HTTP/2 message containing connection-specific header fields; any message containing connection-specific header fields MUST be treated as malformed

[restevez-chs]

thanks @dfawley