net/http: NewFileTransport does not populate Response.Request on redirect #51562
Description
What version of Go are you using (go version)?
$ go version go version go1.17.8 darwin/amd64
Does this issue reproduce with the latest release?
What operating system and processor architecture are you using (go env)?
go env Output
$ go envGO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/aron/Library/Caches/go-build"
GOENV="/Users/aron/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/aron/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/aron/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.17.8"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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/8j/pt4fjhkj11d3xd9344pdspmh0000gn/T/go-build2963024848=/tmp/go-build -gno-record-gcc-switches -fno-common"
What did you do?
The http.NewFileTransport creates a transport where RoundTrip does not populate the Request field of its http.Response on redirects.
Given the following Go program:
package main
import (
"fmt"
"io"
"net/http"
"os"
)
func main() {
transport := &http.Transport{}
transport.RegisterProtocol("file", http.NewFileTransport(http.Dir("./www")))
client := &http.Client{
Transport: transport,
CheckRedirect: func(req *http.Request, via []*http.Request) error {
fmt.Printf("redirect-check: %s\n", req.URL)
// we do our own redirect processing.
return nil
},
}
targetURL := "file:///sub"
fmt.Printf("target url: %s\n", targetURL)
resp, err := client.Get(targetURL)
if err != nil {
fmt.Printf("client error: %s\n")
os.Exit(1)
}
if resp.Request != nil {
fmt.Printf("request url: %s\n", resp.Request.URL)
} else {
fmt.Printf("no response request\n")
}
fmt.Printf("body-start\n")
io.Copy(os.Stdout, resp.Body)
fmt.Printf("body-end\n")
}Using a local directory structure:
www/
sub/
index.html
What did you expect to see?
I expected the program to print:
target url: file:///sub
redirect-check: file:///sub/
request url: file:///sub/
body-start
<html><body>sub</body></html>
body-end
The request url print line indicates that the http.Response returned by the client has its Request field populated, which allows the caller to understand the final URL requested along the (local) redirect chain.
What did you see instead?
Using Go 1.17.8, the program prints:
$ go run main.go
target url: file:///sub
redirect-check: file:///sub/
no response request
body-start
<html><body>sub</body></html>
body-end
The no response redirect indicates that the http.Response returned by the client has an empty Request field, which is different than the behavior seen when using non-file transports.