net/http: Double slash in request leads Method to always be GET

[heathcliff26]

Go version

go version go1.23.0 linux/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/user/.cache/go-build'
GOENV='/home/user/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/user/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/user/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.0'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/user/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/user/repos/testrepo/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3255200026=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I accidentally created a double slash in an http request URL. I have written the following to reproduce:

Server server.go:

package main

import "net/http"

func main() {
	http.HandleFunc("/", func(rw http.ResponseWriter, req *http.Request) {
		if req.Method != http.MethodPost {
			rw.WriteHeader(http.StatusBadRequest)
			rw.Write([]byte("Wrong request type: " + req.Method))
		} else {
			rw.Write([]byte("Success"))
		}
	})

	err := http.ListenAndServe("localhost:8080", nil)
	if err != nil {
		panic(err)
	}
}

Client client.go:

package main

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

func main() {
	req, err := http.NewRequest(http.MethodPost, "http://localhost:8080/"+"/foo/bar", strings.NewReader("test"))
	if err != nil {
		panic(fmt.Errorf("Failed to create request: %v", err))
	}
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(fmt.Errorf("Failed to send request: %v", err))
	}
	buf, err := io.ReadAll(res.Body)
	if err != nil {
		panic(fmt.Errorf("Failed to read response body: %v", err))
	}
	fmt.Println(string(buf))
}

What did you see happen?

Server receives a GET request, with no errors on the client/server side

What did you expect to see?

Server receives a POST request, or possible an error when creating the request.

[gabyhelp]

Related Issues and Documentation

• net/http: request.Method is wrong when path start by // #29584
• import/path: issue title #68253 (closed)
• net/http: double escape of URL #25208 (closed)
• net/http: Request method does not default to GET with http2 #31061 (closed)
• net/http: redirect with 308 rather than 301 #60769
• net/http: invalid http request methods accepted in NewRequest and NewRequestWithContext #44291 (closed)
• affected/package: http #59759 (closed)
• net/http: incorrectly redirect (301) if request payload include port number #51892
• affected/package: net/http Cannot handle certain invalid request URLs #53179 (closed)
• net/http: 301 redirect loses POST data #12456 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[seankhliao]

The server returns a redirect to a clean path. Changing to GET is expected for the given http response code.

Closing as working as intended.