[+] allow CORS from http://localhost:4000 for webui debugging (#439)

src/webserver/cors.go

@@ -0,0 +1,18 @@
+package webserver
+
+import (
+	"net/http"
+)
+
+func corsMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "http://localhost:4000") //check src/webui/.env
+		w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
+		w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, token")
+		if r.Method == "OPTIONS" {
+			w.WriteHeader(http.StatusOK)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}

src/webserver/webserver.go

@@ -36,7 +36,7 @@ func Init(opts config.WebUIOpts, webuifs fs.FS, mrw metrics.ReaderWriter, srw so
 			ReadTimeout:    10 * time.Second,
 			WriteTimeout:   10 * time.Second,
 			MaxHeaderBytes: 1 << 20,
-			Handler:        mux,
+			Handler:        corsMiddleware(mux),
 		},
 		opts,
 		webuifs,