From 978519785eb769e57b262dd9ef13037c5137a090 Mon Sep 17 00:00:00 2001
From: Emil Lundberg <emil@yubico.com>
Date: Thu, 30 Jun 2022 16:14:41 +0200
Subject: [PATCH] Extract struct splitMux

---
 lib/api/api.go | 40 +++++++++++++++++++++++++++++++---------
 1 file changed, 31 insertions(+), 9 deletions(-)

diff --git a/lib/api/api.go b/lib/api/api.go
index 7e5a640fa56..7e7ff5dd477 100644
--- a/lib/api/api.go
+++ b/lib/api/api.go
@@ -368,22 +368,23 @@ func (s *service) Serve(ctx context.Context) error {
 	}
 
 	// The main routing handler
-	unauthenticatedMux := http.NewServeMux()
-	mux.Handle("/rest/", noCacheRestMux)
-	unauthenticatedMux.Handle("/rest/", handler)
-	mux.HandleFunc("/qr/", s.getQR)
-	unauthenticatedMux.Handle("/qr/", handler)
+	mainMuxBuilder := splitMux{
+		fallbackHandler: &handler,
+		fallbackMux: mux, // Authenticated section
+		mainMux: http.NewServeMux(), // Unauthenticated section
+	}
+	mainMuxBuilder.Handle("/rest/", noCacheRestMux)
+	mainMuxBuilder.HandleFunc("/qr/", s.getQR)
 
 	// Handle the special meta.js path
-	mux.HandleFunc("/meta.js", s.getJSMetadata)
-	unauthenticatedMux.Handle("/meta.js", handler)
+	mainMuxBuilder.HandleFunc("/meta.js", s.getJSMetadata)
 
 	// Serve compiled in assets unless an asset directory was set (for development)
-	unauthenticatedMux.Handle("/", s.statics)
+	mainMuxBuilder.mainMux.Handle("/", s.statics)
 
 	srv := http.Server{
 		// Redirect to HTTPS if we are supposed to
-		Handler: debugMiddleware(redirectToHTTPSMiddleware(guiCfg.UseTLS(), unauthenticatedMux)),
+		Handler: debugMiddleware(redirectToHTTPSMiddleware(guiCfg.UseTLS(), mainMuxBuilder.mainMux)),
 		// ReadTimeout must be longer than SyncthingController $scope.refresh
 		// interval to avoid HTTP keepalive/GUI refresh race.
 		ReadTimeout: 15 * time.Second,
@@ -446,6 +447,27 @@ func (s *service) Serve(ctx context.Context) error {
 	return err
 }
 
+// The purpose of splitMux is to help have an unauthenticated section of the API
+// and have everything else fall back to the authenticated segment.
+// The Handle and HandleFunc methods here let you call a "handle" function once
+// but have the path set up in both the unauthenticated "top" mux and the fallback mux.
+// The fallbackHandler is also needed since the fallbackHandler wraps the fallbackMux,
+// but routing paths are registered in the fallbackMux,
+// and the mainMux needs to be configured with the same paths.
+type splitMux struct {
+	fallbackHandler *http.Handler
+	fallbackMux *http.ServeMux
+	mainMux *http.ServeMux
+}
+func (s *splitMux) Handle(path string, handler http.Handler) {
+	s.fallbackMux.Handle(path, handler)
+	s.mainMux.Handle(path, *s.fallbackHandler)
+}
+func (s *splitMux) HandleFunc(path string, handler http.HandlerFunc) {
+	s.fallbackMux.Handle(path, handler)
+	s.mainMux.Handle(path, *s.fallbackHandler)
+}
+
 // Complete implements suture.IsCompletable, which signifies to the supervisor
 // whether to stop restarting the service.
 func (s *service) Complete() bool {