fix(middleware): define middleware in a more streamlined way

handler/default.go

@@ -35,5 +35,9 @@ func GetHandler(d *sql.DB, serverSettings *types.ServerSettings) http.Handler {
 
 	authHandler.handle(router)
 
-	return middleware.Logging(middleware.ContentSecurityPolicy(middleware.EnableCors(serverSettings, router)))
+	return middleware.Wrapper(
+		router,
+		middleware.Log,
+		middleware.ContentSecurityPolicy,
+		middleware.Cors(serverSettings))
 }

middleware/content_security_policiy.go

@@ -5,6 +5,8 @@ import "net/http"
 func ContentSecurityPolicy(next http.Handler) http.Handler {
 
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// While this value can be overridden, it can't be moved to after the next.ServeHTTP call,
+		// because if the response writer get's closed, the headers can't be set anymore
 		w.Header().Set("Content-Security-Policy", "default-src 'self' https://umami.me-fit.eu")
 
 		next.ServeHTTP(w, r)

middleware/cors.go

@@ -6,17 +6,18 @@ import (
 	"net/http"
 )
 
-func EnableCors(serverSettings *types.ServerSettings, next http.Handler) http.Handler {
+func Cors(serverSettings *types.ServerSettings) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Access-Control-Allow-Origin", serverSettings.BaseUrl)
+			w.Header().Set("Access-Control-Allow-Methods", "GET, POST, DELETE")
 
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.Method == "OPTIONS" {
-		w.Header().Set("Access-Control-Allow-Origin", serverSettings.BaseUrl)
+				w.WriteHeader(http.StatusOK)
-		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, DELETE")
+				return
+			}
 
-		if r.Method == "OPTIONS" {
+			next.ServeHTTP(w, r)
-			w.WriteHeader(http.StatusOK)
+		})
-			return
+	}
-		}
-
-		next.ServeHTTP(w, r)
-	})
 }

middleware/logger.go

@@ -30,7 +30,7 @@ func (w *WrappedWriter) WriteHeader(code int) {
 	w.StatusCode = code
 }
 
-func Logging(next http.Handler) http.Handler {
+func Log(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		start := time.Now()
 

middleware/wrapper.go

@@ -0,0 +1,13 @@
+package middleware
+
+import "net/http"
+
+func Wrapper(next http.Handler, handlers ...func(http.Handler) http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		lastHandler := next
+		for i := len(handlers) - 1; i >= 0; i-- {
+			lastHandler = handlers[i](lastHandler)
+		}
+		lastHandler.ServeHTTP(w, r)
+	})
+}