package main import ( "fmt" "net/http" ) func serve() { http.HandleFunc("/user", func(w http.ResponseWriter, r *http.Request) { r.ParseForm() username := r.Form.Get("username") // $ Source[go/reflected-xss] if !isValidUsername(username) { // BAD: a request parameter is incorporated without validation into the response fmt.Fprintf(w, "%q is an unknown user", username) // $ Alert[go/reflected-xss] } else { // TODO: Handle successful login } }) http.ListenAndServe(":80", nil) }