x/net/http2: pseudo header :protocol can not appear after regular header fields

[aojea]

Found during the implementation of the websockets protocol over http2 on the websocket server https://go-review.googlesource.com/c/net/+/632755

2024/12/08 14:50:29 http2: Transport encoding header ":protocol" = "websocket"
2024/12/08 14:50:29 http2: Framer 0xc0001be460: read SETTINGS flags=ACK len=0
2024/12/08 14:50:29 http2: Transport encoding header "accept-encoding" = "gzip"
2024/12/08 14:50:29 http2: Framer 0xc0001600e0: read SETTINGS flags=ACK len=0
2024/12/08 14:50:29 http2: Transport encoding header "user-agent" = "Go-http-client/2.0"
2024/12/08 14:50:29 http2: Transport received SETTINGS flags=ACK len=0
2024/12/08 14:50:29 http2: Framer 0xc0001600e0: wrote HEADERS flags=END_HEADERS stream=1 len=89
2024/12/08 14:50:29 http2: server read frame SETTINGS flags=ACK len=0
2024/12/08 14:50:29 http2: Framer 0xc0001be460: read HEADERS flags=END_HEADERS stream=1 len=89
2024/12/08 14:50:29 http2: decoded hpack field header field ":authority" = "127.0.0.1:44877"
2024/12/08 14:50:29 http2: decoded hpack field header field ":method" = "CONNECT"
2024/12/08 14:50:29 http2: decoded hpack field header field ":path" = "/echo"
2024/12/08 14:50:29 http2: decoded hpack field header field ":scheme" = "https"
2024/12/08 14:50:29 http2: decoded hpack field header field "sec-websocket-version" = "13"
2024/12/08 14:50:29 http2: decoded hpack field header field ":protocol" = "websocket"
2024/12/08 14:50:29 http2: invalid header: pseudo header field after regular
2024/12/08 14:50:29 http2: Framer 0xc0001be460: wrote RST_STREAM stream=1 len=4 ErrCode=PROTOCOL_ERROR
2024/12/08 14:50:29 http2: Framer 0xc0001600e0: read RST_STREAM stream=1 len=4 ErrCode=PROTOCOL_ERROR
2024/12/08 14:50:29 http2: Transport received RST_STREAM stream=1 len=4 ErrCode=PROTOCOL_ERROR
2024/12/08 14:50:29 http2: Transport closing idle conn 0xc0001621c0 (forSingleUse=false, maxStream=1)
2024/12/08 14:50:29 http2: Transport readFrame error on conn 0xc0001621c0: (*net.OpError) read tcp 127.0.0.1:51842->127.0.0.1:44877: use of closed network connection

/cc @neild

[gabyhelp]

Related Issues

• net/http: cannot set custom/special pseudo-headers when using HTTP/2 #32763 (closed)
• x/net/http2: server cannot process Trailer frames correctly after RST_STREAM #58286
• x/net/http2: PROTOCOL_ERROR after GOAWAY #32112 (closed)
• net/http: h2 does not support other net.Conn than *tls.Conn #55076
• net/http/httputil: ReverseProxy fails to proxy h2c #33452 (closed)
• x/net/http2: Server rejects Transport with ErrCodeProtocol stream error #47635
• x/net/http2: certain HTTP2 requests sends a "END_STREAM" prematurely #28206 (closed)
• x/net/http2: Race in handler execution results in zero-byte data frame, causing incompatibility with gRPC #56317 (closed)
• net/http/httputil: ReverseProxy doesn't proxy grpc without help due to 'te' header handling #21096 (closed)
• x/net/http2: should interpret Connection: close request header as Request.Close = true #14227 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[cagedmantis]

@aojea Would you be able to provide a snippet of code that could easily reproduce this condition?

[aojea]

@cagedmantis I found that using the test in https://go-review.googlesource.com/c/net/+/632755

You can check that out

go test ./websocket -v -count 1 -c
GODEBUG=http2debug=2 stress ./websocket.test -test.run TestEchoHTTP2

after a few seconds you'll find a trace in any of the logged files

grep -i pseudo /tmp/go-stress-20241208T150059-*
/tmp/go-stress-20241208T150059-1000814886:2024/12/08 15:01:07 http2: invalid header: pseudo header field after regular
/tmp/go-stress-20241208T150059-101774849:2024/12/08 15:01:14 http2: invalid header: pseudo header field after regular
/tmp/go-stress-20241208T150059-1025520657:2024/12/08 15:01:06 http2: invalid header: pseudo header field after regular
/tmp/go-stress-20241208T150059-1038053119:2024/12/08 15:01:02 http2: invalid header: pseudo header field after regular
/tmp/go-stress-20241208T150059-1041408016:2024/12/08 15:01:16 http2: invalid header: pseudo header field after regular
/tmp/go-stress-20241208T150059-1106862457:2024/12/08 15:01:21 http2: invalid header: pseudo header field after regular
/tmp/go-stress-20241208T150059-1120817889:2024/12/08 15:01:17 http2: invalid header: pseudo header field after regular

If you see here https://github.com/golang/net/blob/552d8ac903a11a9fde71a88732f5b58b6b394178/http2/server.go#L2268-L2277 the :protocol pseudo header is added as a normal header and it is implemented over a map, so listing will not guarantee the order IIUIC

rp.header = make(http.Header)
	for _, hf := range f.RegularFields() {
		rp.header.Add(sc.canonicalHeader(hf.Name), hf.Value)
	}
	if rp.authority == "" {
		rp.authority = rp.header.Get("Host")
	}
	if rp.protocol != "" {
		rp.header.Set(":protocol", rp.protocol)
	}

[cagedmantis]

cc @tombergan

[prattmic]

I'm tentatively marking this as a release blocker, as #71128 points out that https://go.dev/cl/610977 is vendored into 1.24 and this sounds like a bug/regression in that CL (though I may be misunderstanding).

[gopherbot]

Change https://go.dev/cl/641476 mentions this issue: http2: encode :protocol pseudo-header before regular headers