package main import ( "os" "strings" "flag" "fmt" "log" "net/http" "io/ioutil" "encoding/json" "encoding/base64" "crypto/rand" "crypto/tls" "html/template" "github.com/gorilla/sessions" "github.com/go-ldap/ldap/v3" ) type ConfigFile struct { HttpBindAddr string `json:"http_bind_addr"` SessionKey string `json:"session_key"` LdapServerAddr string `json:"ldap_server_addr"` LdapTLS bool `json:"ldap_tls"` UserFormat string `json:"user_format"` } var configFlag = flag.String("config", "./config.json", "Configuration file path") var config *ConfigFile const SESSION_NAME = "guichet_session" var store *sessions.CookieStore = nil func readConfig() ConfigFile{ key_bytes := make([]byte, 32) n, err := rand.Read(key_bytes) if err!= nil || n != 32 { log.Fatal(err) } config_file := ConfigFile{ HttpBindAddr: ":9991", SessionKey: base64.StdEncoding.EncodeToString(key_bytes), LdapServerAddr: "ldap://127.0.0.1:389", LdapTLS: false, UserFormat: "cn=%s,ou=users,dc=example,dc=com", } _, err = os.Stat(*configFlag) if os.IsNotExist(err) { // Generate default config file log.Printf("Generating default config file as %s", *configFlag) bytes, err := json.MarshalIndent(&config_file, "", " ") if err != nil { log.Fatal(err) } err = ioutil.WriteFile(*configFlag, bytes, 0644) if err != nil { log.Fatal(err) } return config_file } if err != nil { log.Fatal(err) } bytes, err := ioutil.ReadFile(*configFlag) if err != nil { log.Fatal(err) } err = json.Unmarshal(bytes, &config_file) if err != nil { log.Fatal(err) } return config_file } func main() { flag.Parse() config_file := readConfig() config = &config_file store = sessions.NewCookieStore([]byte(config.SessionKey)) http.HandleFunc("/", handleHome) staticfiles := http.FileServer(http.Dir("static")) http.Handle("/static/", http.StripPrefix("/static/", staticfiles)) err := http.ListenAndServe(config.HttpBindAddr, logRequest(http.DefaultServeMux)) if err != nil { log.Fatal("Cannot start http server: ", err) } } type LoginInfo struct { Username string DN string Password string } func logRequest(handler http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { log.Printf("%s %s %s\n", r.RemoteAddr, r.Method, r.URL) handler.ServeHTTP(w, r) }) } func checkLogin(w http.ResponseWriter, r *http.Request) *LoginInfo { session, err := store.Get(r, SESSION_NAME) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return nil } login_info, has_login_info := session.Values["login_info"] if !has_login_info { return handleLogin(w, r) } return login_info.(*LoginInfo) } func ldapOpen(w http.ResponseWriter) *ldap.Conn { l, err := ldap.DialURL(config.LdapServerAddr) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return nil } if config.LdapTLS { err = l.StartTLS(&tls.Config{InsecureSkipVerify: true}) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return nil } } return l } // Templates ---- type LoginFormData struct { Username string ErrorMessage string } var ( templateLogin = template.Must(template.ParseFiles("templates/layout.html", "templates/login.html")) ) // Page handlers ---- func handleHome(w http.ResponseWriter, r *http.Request) { login := checkLogin(w, r) if login == nil { return } fmt.Fprintf(w, "Welcome, %s!", login.Username) } func handleLogin(w http.ResponseWriter, r *http.Request) *LoginInfo { if r.Method == "GET" { templateLogin.Execute(w, LoginFormData{}) return nil } else if r.Method == "POST" { r.ParseForm() username := strings.Join(r.Form["username"], "") user_dn := strings.ReplaceAll(config.UserFormat, "%s", username) login_info := &LoginInfo{ DN: user_dn, Username: username, Password: strings.Join(r.Form["password"], ""), } l := ldapOpen(w) if l == nil { return nil } err := l.Bind(user_dn, login_info.Password) if err != nil { templateLogin.Execute(w, LoginFormData{ Username: username, ErrorMessage: err.Error(), }) return nil } // Successfully logged in, save it to session session, err := store.Get(r, SESSION_NAME) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return nil } session.Values["login_info"] = login_info return login_info } else { http.Error(w, "Unsupported method", http.StatusBadRequest) return nil } }