fix: missing security headers on every response, including the SPA and uploaded images

api/middleware/securityHeaders.go

@@ -0,0 +1,33 @@
+package middleware
+
+import "net/http"
+
+const contentSecurityPolicy = "default-src 'self'; " +
+	"script-src 'self'; " +
+	"style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; " +
+	"font-src 'self' https://fonts.gstatic.com; " +
+	"img-src 'self' data: blob: https:; " +
+	"connect-src 'self'; " +
+	"object-src 'none'; " +
+	"base-uri 'self'; " +
+	"form-action 'self'; " +
+	"frame-ancestors 'none'"
+
+const strictTransportSecurity = "max-age=31536000"
+
+func SecurityHeaders(hsts bool) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			h := w.Header()
+			h.Set("Content-Security-Policy", contentSecurityPolicy)
+			h.Set("X-Content-Type-Options", "nosniff")
+			h.Set("X-Frame-Options", "DENY")
+			h.Set("Referrer-Policy", "strict-origin-when-cross-origin")
+			h.Set("Cross-Origin-Opener-Policy", "same-origin")
+			if hsts {
+				h.Set("Strict-Transport-Security", strictTransportSecurity)
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}

api/router.go

@@ -280,6 +280,7 @@ func InitRoutes(container *UseCases, settings config.Settings) *chi.Mux {
 	frontend := InitFrontendRoutes(settings.Environment)
 
 	apiRouter := chi.NewRouter()
+	apiRouter.Use(middleware.SecurityHeaders(settings.IsProduction()))
 	enableCorsIfConfigured(apiRouter, settings.CorsAllowedOrigins)
 	apiRouter.Use(chimiddleware.GetHead)
 	apiRouter.Get("/healthz", GetHealth)