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Problem

So I'm not really sure if this is a bug or anything, and this is also my first bug report so I apologize for my lack of knowledge on correctly reporting a bug.

I was trying to create a SPA using gorilla/mux and kept running into issues with displaying my webpage. I knew my code was correct but it had something to do with the file paths inside the SPA handler itself because when I was running my code I was getting a StatusInternalServerError. All my file paths were correct so it had to be something with the ServeHTTP function itself. I later found it to be an issue with the path as shown below.

Versions

go version go1.13.4 windows/amd64

github.com/gorilla/mux v1.7.4 …

main.go

type spaHandler struct {
	staticPath string
	indexPath  string
}

func (h spaHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	path, err := filepath.Abs(r.URL.Path)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	path = filepath.Join(h.staticPath, path) //this is the part of the code I changed to fix my issue

	_, err = os.Stat(path)
	if os.IsNotExist(err) {
		http.ServeFile(w, r, filepath.Join(h.staticPath, h.indexPath))
		return
	} else if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	http.FileServer(http.Dir(h.staticPath)).ServeHTTP(w, r)
}

func main() {
	router := mux.NewRouter()
	spa := spaHandler{staticPath: "./admin/build", indexPath: "index.html"}
	router.PathPrefix("/").Handler(spa)
	log.Fatal(http.ListenAndServe(":8080", router))
}

Code was changed to below, and started to work perfectly fine.

path = filepath.Join(h.staticPath, r.URL.Path) 

…

I don't know whether or not to report this as a fix to the actual public code or not. Still new to contributing.

Confirming I have the same problem with the example SPA code (using Windows).

	// get the absolute path to prevent directory traversal
	path, err := filepath.Abs(r.URL.Path)
	if err != nil {
		// if we failed to get the absolute path respond with a 400 bad request
		// and stop
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	fmt.Println(path) // returns: D:\

	// prepend the path with the path to the static directory

	path = filepath.Join(h.StaticPath, path)
	fmt.Println(path) // returns: build\D:

	path = filepath.Join(h.StaticPath, r.URL.Path)
	fmt.Println(path) // returns: build

This issue has been automatically marked as stale because it hasn't seen a recent update. It'll be automatically closed in a few days.

Not so stale.

is there an update on this?

This problem appears on windows. For an unknown reason filepath.abs returns the storage letter, so the path begins with "C:/" (or "D:/", or whatever letter followed by ":/"), just replace "C:/" by "/" and it will works great !

path, err := filepath.Abs(r.URL.Path)
path = strings.Replace(path, `C:\`, "/", 1)

Solution found on reddit : https://www.reddit.com/r/golang/comments/pvltgk/having_trouble_getting_the_gorillamux_single_page/

I'm beginner in golang (even more with windows stuff) so i don't feel comfortable to make a pull request but at least here is quick and dirty hotfix !

This issue has been automatically marked as stale because it hasn't seen a recent update. It'll be automatically closed in a few days.

I can finally triage this issue. Will work on fixing docs and add a new test case for the same.