package main import ( "fmt" "html" "net/http" ) func serve1() { http.HandleFunc("/user", func(w http.ResponseWriter, r *http.Request) { r.ParseForm() username := r.Form.Get("username") if !isValidUsername(username) { // GOOD: a request parameter is escaped before being put into the response fmt.Fprintf(w, "%q is an unknown user", html.EscapeString(username)) } else { // TODO: do something exciting } }) http.ListenAndServe(":80", nil) }