package middleware import "net/http" func SecurityHeaders(next http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { w.Header().Set("X-Content-Type-Options", "nosniff") w.Header().Set("X-Frame-Options", "DENY") w.Header().Set("X-XSS-Protection", "1; mode=block") w.Header().Set("Referrer-Policy", "strict-origin-when-cross-origin") // Content-Security-Policy can be very strict, maybe good to start lenient or specific. // For an API, it's less critical than a frontend serving HTML, but good practice. w.Header().Set("Content-Security-Policy", "default-src 'none'") w.Header().Set("Cache-Control", "no-store, max-age=0") next.ServeHTTP(w, r) }) }