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net/http: http.ListenAndServeTLS lowercasing request header keys #15472

deankarn opened this issue Apr 27, 2016 · 3 comments

net/http: http.ListenAndServeTLS lowercasing request header keys #15472

deankarn opened this issue Apr 27, 2016 · 3 comments


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@deankarn deankarn commented Apr 27, 2016

Please answer these questions before submitting your issue. Thanks!

  1. What version of Go are you using (go version)?
go version go1.6.2 darwin/amd64
  1. What operating system and processor architecture are you using (go env)?
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fno-common"
  1. What did you do?

unfortunately I could not make a runnable example, a valid SSL Certificate seems to be needed to recreate this issue, using:

tr := &http.Transport{
    TLSClientConfig: &tls.Config{InsecureSkipVerify: true},

client := &http.Client{Transport: tr}


tlsConfig := &tls.Config{
    Certificates: make([]tls.Certificate, 1),

tlsConfig.Certificates[0], err = tls.X509KeyPair([]byte(httpPem), []byte(httpKey))
if err != nil {
server = &http.Server{Addr: port, Handler: handler, TLSConfig: tlsConfig}

the issue does not occur, only using the http.ListenAndServerTLS that I could find so far. below is what causes the issue (need to use your own Cretificates + URL.

package main

import (

func main() {
    go server()


    req, err := http.NewRequest("GET", "https://localhost:8080", nil)
    if err != nil {
        log.Fatal(errors.New("Error Creating Request:" + err.Error()))

    req.Header.Set("UPDATE_API_KEY", "Efewfjnewjkfewjkfew")

    // tr := &http.Transport{
    //  TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
    // }

    // client := &http.Client{Transport: tr}

    // This issue is very specific, using the code above actually works as expected
    client := &http.Client{}

    _, err = client.Do(req)
    if err != nil {
        log.Fatal(fmt.Sprint("ERROR Fetching Updates:", err))

func server() {

    handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

    http.ListenAndServeTLS(":8080", "path to certFile", "path to keyFile", handler)

Go 1.6 does not have this issue, either patch 1.6.1 or 1.6.2 caused this.

  1. What did you expect to see?
map[User-Agent:[Go-http-client/1.1] UPDATE_API_KEY:[Efewfjnewjkfewjkfew] Accept-Encoding:[gzip]]

map key of "UPDATE_API_KEY" is correct
  1. What did you see instead?
map[Accept-Encoding:[gzip] User-Agent:[Go-http-client/2.0] update_api_key:[Efewfjnewjkfewjkfew]]

map key of "update_api_key" is not correct

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@bradfitz bradfitz commented Apr 27, 2016

The difference is HTTP/2. With HTTP/2, all header fields must be sent lowercase, mandated by the spec. In HTTP/1 any case is allowed, and they should be compared case-insensitively.

Go tries to map things into their Go-canonical form via but because it has an underscore in it, Go does nothing (but fixed in Go 1.7).

I'd recommend using a hyphen instead of an underscore if possible. Otherwise you'll have to enumerate over the map keys looking for the "UpDaTE_api_KEY" yourself, normalizing the case of the keys as you look.


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@bradfitz bradfitz commented Apr 27, 2016

Btw, b24c6fb (issue #13767) was the commit which fixed this. It will be included in Go 1.7.


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@deankarn deankarn commented Apr 27, 2016

Thanks 👍

@deankarn deankarn closed this Apr 27, 2016
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