server: add SPA static router

Author: x1unix

cmd/playground/main.go

@@ -62,7 +62,7 @@ func start(packagesFile, addr, goRoot string, debug bool) error {
 
 	r := mux.NewRouter()
 	langserver.New(packages).Mount(r.PathPrefix("/api").Subrouter())
-	r.PathPrefix("/").Handler(http.FileServer(http.Dir("./public")))
+	r.PathPrefix("/").Handler(langserver.SpaFileServer("./public"))
 
 	zap.S().Infof("Listening on %q", addr)
 

pkg/langserver/spa.go

@@ -0,0 +1,70 @@
+package langserver
+
+import (
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+// Advanced static server
+type spaFileServer struct {
+	root            http.Dir
+	NotFoundHandler func(http.ResponseWriter, *http.Request)
+}
+
+func (fs *spaFileServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+
+	if containsDotDot(r.URL.Path) {
+		Errorf(http.StatusBadRequest, "Bad Request").Write(w)
+		return
+	}
+
+	//if empty, set current directory
+	dir := string(fs.root)
+	if dir == "" {
+		dir = "."
+	}
+
+	//add prefix and clean
+	upath := r.URL.Path
+	if !strings.HasPrefix(upath, "/") {
+		upath = "/" + upath
+		r.URL.Path = upath
+	}
+	upath = path.Clean(upath)
+
+	//path to file
+	name := path.Join(dir, filepath.FromSlash(upath))
+
+	//check if file exists
+	f, err := os.Open(name)
+	if err != nil {
+		if os.IsNotExist(err) {
+			Errorf(http.StatusNotFound, "Not Found").Write(w)
+			return
+		}
+	}
+	defer f.Close()
+
+	http.ServeFile(w, r, name)
+}
+
+func containsDotDot(v string) bool {
+	if !strings.Contains(v, "..") {
+		return false
+	}
+	for _, ent := range strings.FieldsFunc(v, isSlashRune) {
+		if ent == ".." {
+			return true
+		}
+	}
+	return false
+}
+
+func isSlashRune(r rune) bool { return r == '/' || r == '\\' }
+
+func SpaFileServer(root http.Dir) http.Handler {
+	return &spaFileServer{root: root}
+}