Description
What version of Go are you using (go version)?
$ go version go version go1.12.6 darwin/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="/Users/zg/Library/Caches/go-build" GOEXE="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="darwin" GOOS="darwin" GOPATH="/Users/zg/go" GOPROXY="" GORACE="" GOROOT="/usr/local/go" GOTMPDIR="" GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64" GCCGO="gccgo" CC="clang" CXX="clang++" CGO_ENABLED="1" GOMOD="/Users/zg/Development/gunkit/go.mod" 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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/lg/cht6v2795qn9z07kmcl6h3c40000gn/T/go-build863622379=/tmp/go-build -gno-record-gcc-switches -fno-common"
What did you do?
I know http.Transport will use chunked Encoding automatically when Request has body and Request.Content-Length was set < 0. But this troubled me when I use net.http in my own penetration testing tool, which always need to build a custom chunked body. The code simply looks like the following snippet：
buf := &bytes.Buffer{}
ck := NewCustomChunkedWriter(buf)
ck.WriteString("test")
ck.Close()
req, _ = http.NewRequest("POST", "http://xx.com", buf)
req.Header.Set("Transfer-Encoding", "chunked")Howover, it didn't work as expected. I tried to trace the roundtrip method and found that Transfer-Encoding is in a map named reqWriteExcludeHeader, which looks like a whitelist when writing request header.
And if I set req.Transfer-Encoding = []string{"chunked"}， the request body will be chunked twice! one from my customChunkedWriter, the other from the internal chunked writer.
Finally, I believe there is actually no way to make it. I think It's not a intended behavior. It should be great if it acts like Accept-Encoding.
If the Transport requests gzip on its own and gets a gzipped response, it's transparently decoded in the Response.Body. However, if the user explicitly requested gzip it is not automatically uncompressed.
Related issue: #28026
What did you expect to see?
If I send Transfer-Encoding explicitly, transport should keep the header and do nothing about the request body.
What did you see instead?
Described as above.