x/net/http2: Required ciphers error message is confusing

[scottmmjackson]

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

$ go version
go version go1.12.10 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build134947043=/tmp/go-build -gno-record-gcc-switches"

What did you do?

In cipher customization code, included TLS_AES_128_GCM_SHA256 in CipherSuites member to a tls.Config struct, which was subsequently passed to http.Server and ListenAndServeTLS()

What did you expect to see?

Proper startup

What did you see instead?

http2: TLSConfig.CipherSuites is missing an HTTP/2-required AES_128_GCM_SHA256 cipher.

What the test actually wants is TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256. I imagine that prior to the introduction of TLS_AES_128_GCM_SHA256 this error message was less ambiguous. However, it is now misleading.

[andybons]

@FiloSottile @bradfitz

[gopherbot]

Change https://golang.org/cl/200317 mentions this issue: http2: make CipherSuites validation error more verbose

[gopherbot]

Change https://golang.org/cl/209077 mentions this issue: net/http: update bundled x/net/http2