No way to retrieve the proxy host name

[gadelkareem]

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

$ go version
1.16.4

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
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/gadelkareem/Library/Caches/go-build"
GOENV="/Users/gadelkareem/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/gadelkareem/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/gadelkareem/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/opt/go/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/opt/go/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.16.4"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/gadelkareem/Documents/test/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 -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/7p/qc_c3wz575z8h0000gn/T/go-build1195731376=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Running HTTP server:

package main

import (
    "fmt"
    "net"
    "net/http"
)

func main() {
    (&http.Server{
        Addr: ":8080",
        Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
                fmt.Printf("%+v\n", r.Context().Value(http.ServerContextKey).(*http.Server))
                fmt.Printf("%+v\n", r.Context().Value(http.LocalAddrContextKey).(net.Addr).String())
                fmt.Printf("%+v\n", r)
        }),
    }).ListenAndServe()
}

Run the app:

> go run main.go

Call it as a proxy: (kubernetes.docker.internal is localhost)

curl --proxy-header "Test: test" -x http://kubernetes.docker.internal:8080 -L http://google.com

What did you expect to see?

There is no way to get the original proxy host name

What did you see instead?

> go run main.go
&{Addr::8080 Handler:0x1222680 TLSConfig:0xc000001980 ReadTimeout:0s ReadHeaderTimeout:0s WriteTimeout:0s IdleTimeout:0s MaxHeaderBytes:0 TLSNextProto:map[h2:0x1216fa0] ConnState:<nil> ErrorLog:<nil> BaseContext:<nil> ConnContext:<nil> inShutdown:0 disableKeepAlives:0 nextProtoOnce:{done:1 m:{state:0 sema:0}} nextProtoErr:<nil> mu:{state:0 sema:0} listeners:map[0xc000012d00:{}] activeConn:map[0xc000112a00:{}] doneChan:<nil> onShutdown:[0x121c680]}
127.0.0.1:8080
&{Method:GET URL:http://google.com/ Proto:HTTP/1.1 ProtoMajor:1 ProtoMinor:1 Header:map[Accept:[*/*] Proxy-Connection:[Keep-Alive] Test:[test] User-Agent:[curl/7.64.1]] Body:{} GetBody:<nil> ContentLength:0 TransferEncoding:[] Close:false Host:google.com Form:map[] PostForm:map[] MultipartForm:<nil> Trailer:map[] RemoteAddr:127.0.0.1:60959 RequestURI:http://google.com/ TLS:<nil> Cancel:<nil> Response:<nil> ctx:0xc000028340}

[seankhliao]

This is a limitation of the HTTP protocol

Closing as working as intended