package server import ( "bytes" "context" "embed" _ "embed" // required for go:embed "encoding/json" firebase "firebase.google.com/go" "firebase.google.com/go/messaging" "fmt" "golang.org/x/time/rate" "google.golang.org/api/option" "heckel.io/ntfy/config" "io" "log" "net" "net/http" "regexp" "strconv" "strings" "sync" "time" ) // TODO add "max connections open" limit // TODO add "max messages in a topic" limit // TODO add "max topics" limit // Server is the main server type Server struct { config *config.Config topics map[string]*topic visitors map[string]*visitor firebase subscriber messages int64 mu sync.Mutex } // visitor represents an API user, and its associated rate.Limiter used for rate limiting type visitor struct { limiter *rate.Limiter seen time.Time } // errHTTP is a generic HTTP error for any non-200 HTTP error type errHTTP struct { Code int Status string } func (e errHTTP) Error() string { return fmt.Sprintf("http: %s", e.Status) } const ( messageLimit = 1024 visitorExpungeAfter = 30 * time.Minute ) var ( topicRegex = regexp.MustCompile(`^/[^/]+$`) jsonRegex = regexp.MustCompile(`^/[^/]+/json$`) sseRegex = regexp.MustCompile(`^/[^/]+/sse$`) rawRegex = regexp.MustCompile(`^/[^/]+/raw$`) staticRegex = regexp.MustCompile(`^/static/.+`) //go:embed "index.html" indexSource string //go:embed static webStaticFs embed.FS errHTTPBadRequest = &errHTTP{http.StatusBadRequest, http.StatusText(http.StatusBadRequest)} errHTTPNotFound = &errHTTP{http.StatusNotFound, http.StatusText(http.StatusNotFound)} errHTTPTooManyRequests = &errHTTP{http.StatusTooManyRequests, http.StatusText(http.StatusTooManyRequests)} ) func New(conf *config.Config) (*Server, error) { var firebaseSubscriber subscriber if conf.FirebaseKeyFile != "" { var err error firebaseSubscriber, err = createFirebaseSubscriber(conf) if err != nil { return nil, err } } return &Server{ config: conf, firebase: firebaseSubscriber, topics: make(map[string]*topic), visitors: make(map[string]*visitor), }, nil } func createFirebaseSubscriber(conf *config.Config) (subscriber, error) { fb, err := firebase.NewApp(context.Background(), nil, option.WithCredentialsFile(conf.FirebaseKeyFile)) if err != nil { return nil, err } msg, err := fb.Messaging(context.Background()) if err != nil { return nil, err } return func(m *message) error { _, err := msg.Send(context.Background(), &messaging.Message{ Data: map[string]string{ "id": m.ID, "time": fmt.Sprintf("%d", m.Time), "event": m.Event, "topic": m.Topic, "message": m.Message, }, Notification: &messaging.Notification{ Title: m.Topic, // FIXME convert to ntfy.sh/$topic instead Body: m.Message, ImageURL: "", }, Topic: m.Topic, }) return err }, nil } func (s *Server) Run() error { go func() { ticker := time.NewTicker(s.config.ManagerInterval) for { <-ticker.C s.updateStatsAndExpire() } }() return s.listenAndServe() } func (s *Server) listenAndServe() error { log.Printf("Listening on %s", s.config.ListenHTTP) http.HandleFunc("/", s.handle) return http.ListenAndServe(s.config.ListenHTTP, nil) } func (s *Server) handle(w http.ResponseWriter, r *http.Request) { if err := s.handleInternal(w, r); err != nil { if e, ok := err.(*errHTTP); ok { s.fail(w, r, e.Code, e) } else { s.fail(w, r, http.StatusInternalServerError, err) } } } func (s *Server) handleInternal(w http.ResponseWriter, r *http.Request) error { v := s.visitor(r.RemoteAddr) if !v.limiter.Allow() { return errHTTPTooManyRequests } if r.Method == http.MethodGet && r.URL.Path == "/" { return s.handleHome(w, r) } else if r.Method == http.MethodGet && staticRegex.MatchString(r.URL.Path) { return s.handleStatic(w, r) } else if (r.Method == http.MethodPut || r.Method == http.MethodPost) && topicRegex.MatchString(r.URL.Path) { return s.handlePublish(w, r) } else if r.Method == http.MethodGet && jsonRegex.MatchString(r.URL.Path) { return s.handleSubscribeJSON(w, r) } else if r.Method == http.MethodGet && sseRegex.MatchString(r.URL.Path) { return s.handleSubscribeSSE(w, r) } else if r.Method == http.MethodGet && rawRegex.MatchString(r.URL.Path) { return s.handleSubscribeRaw(w, r) } else if r.Method == http.MethodOptions { return s.handleOptions(w, r) } return errHTTPNotFound } func (s *Server) handleHome(w http.ResponseWriter, r *http.Request) error { _, err := io.WriteString(w, indexSource) return err } func (s *Server) handleStatic(w http.ResponseWriter, r *http.Request) error { http.FileServer(http.FS(webStaticFs)).ServeHTTP(w, r) return nil } func (s *Server) handlePublish(w http.ResponseWriter, r *http.Request) error { t := s.createTopic(r.URL.Path[1:]) reader := io.LimitReader(r.Body, messageLimit) b, err := io.ReadAll(reader) if err != nil { return err } if err := t.Publish(newDefaultMessage(t.id, string(b))); err != nil { return err } w.Header().Set("Access-Control-Allow-Origin", "*") // CORS, allow cross-origin requests s.mu.Lock() s.messages++ s.mu.Unlock() return nil } func (s *Server) handleSubscribeJSON(w http.ResponseWriter, r *http.Request) error { encoder := func(msg *message) (string, error) { var buf bytes.Buffer if err := json.NewEncoder(&buf).Encode(&msg); err != nil { return "", err } return buf.String(), nil } return s.handleSubscribe(w, r, "json", "application/stream+json", encoder) } func (s *Server) handleSubscribeSSE(w http.ResponseWriter, r *http.Request) error { encoder := func(msg *message) (string, error) { var buf bytes.Buffer if err := json.NewEncoder(&buf).Encode(&msg); err != nil { return "", err } if msg.Event != messageEvent { return fmt.Sprintf("event: %s\ndata: %s\n", msg.Event, buf.String()), nil // Browser's .onmessage() does not fire on this! } return fmt.Sprintf("data: %s\n", buf.String()), nil } return s.handleSubscribe(w, r, "sse", "text/event-stream", encoder) } func (s *Server) handleSubscribeRaw(w http.ResponseWriter, r *http.Request) error { encoder := func(msg *message) (string, error) { if msg.Event == "" { // only handle default events return strings.ReplaceAll(msg.Message, "\n", " ") + "\n", nil } return "\n", nil // "keepalive" and "open" events just send an empty line } return s.handleSubscribe(w, r, "raw", "text/plain", encoder) } func (s *Server) handleSubscribe(w http.ResponseWriter, r *http.Request, format string, contentType string, encoder messageEncoder) error { t := s.createTopic(strings.TrimSuffix(r.URL.Path[1:], "/"+format)) // Hack since, err := parseSince(r) if err != nil { return err } poll := r.URL.Query().Has("poll") sub := func(msg *message) error { m, err := encoder(msg) if err != nil { return err } if _, err := w.Write([]byte(m)); err != nil { return err } if fl, ok := w.(http.Flusher); ok { fl.Flush() } return nil } w.Header().Set("Access-Control-Allow-Origin", "*") // CORS, allow cross-origin requests w.Header().Set("Content-Type", contentType) if poll { return sendOldMessages(t, since, sub) } subscriberID := t.Subscribe(sub) defer t.Unsubscribe(subscriberID) if err := sub(newOpenMessage(t.id)); err != nil { // Send out open message return err } if err := sendOldMessages(t, since, sub); err != nil { return err } for { select { case <-t.ctx.Done(): return nil case <-r.Context().Done(): return nil case <-time.After(s.config.KeepaliveInterval): if err := sub(newKeepaliveMessage(t.id)); err != nil { // Send keepalive message return err } } } } func sendOldMessages(t *topic, since time.Time, sub subscriber) error { if since.IsZero() { return nil } for _, m := range t.Messages(since) { if err := sub(m); err != nil { return err } } return nil } func parseSince(r *http.Request) (time.Time, error) { if !r.URL.Query().Has("since") { return time.Time{}, nil } if since, err := strconv.ParseInt(r.URL.Query().Get("since"), 10, 64); err == nil { return time.Unix(since, 0), nil } if d, err := time.ParseDuration(r.URL.Query().Get("since")); err == nil { return time.Now().Add(-1 * d), nil } return time.Time{}, errHTTPBadRequest } func (s *Server) handleOptions(w http.ResponseWriter, r *http.Request) error { w.Header().Set("Access-Control-Allow-Origin", "*") // CORS, allow cross-origin requests w.Header().Set("Access-Control-Allow-Methods", "GET, PUT, POST") return nil } func (s *Server) createTopic(id string) *topic { s.mu.Lock() defer s.mu.Unlock() if _, ok := s.topics[id]; !ok { s.topics[id] = newTopic(id) if s.firebase != nil { s.topics[id].Subscribe(s.firebase) } } return s.topics[id] } func (s *Server) updateStatsAndExpire() { s.mu.Lock() defer s.mu.Unlock() // Expire visitors from rate visitors map for ip, v := range s.visitors { if time.Since(v.seen) > visitorExpungeAfter { delete(s.visitors, ip) } } // Prune old messages, remove topics without subscribers for _, t := range s.topics { t.Prune(s.config.MessageBufferDuration) subs, msgs := t.Stats() if msgs == 0 && (subs == 0 || (s.firebase != nil && subs == 1)) { delete(s.topics, t.id) } } // Print stats var subscribers, messages int for _, t := range s.topics { subs, msgs := t.Stats() subscribers += subs messages += msgs } log.Printf("Stats: %d message(s) published, %d topic(s) active, %d subscriber(s), %d message(s) buffered, %d visitor(s)", s.messages, len(s.topics), subscribers, messages, len(s.visitors)) } // visitor creates or retrieves a rate.Limiter for the given visitor. // This function was taken from https://www.alexedwards.net/blog/how-to-rate-limit-http-requests (MIT). func (s *Server) visitor(remoteAddr string) *visitor { s.mu.Lock() defer s.mu.Unlock() ip, _, err := net.SplitHostPort(remoteAddr) if err != nil { ip = remoteAddr // This should not happen in real life; only in tests. } v, exists := s.visitors[ip] if !exists { v = &visitor{ rate.NewLimiter(s.config.Limit, s.config.LimitBurst), time.Now(), } s.visitors[ip] = v return v } v.seen = time.Now() return v } func (s *Server) fail(w http.ResponseWriter, r *http.Request, code int, err error) { log.Printf("[%s] %s - %d - %s", r.RemoteAddr, r.Method, code, err.Error()) w.WriteHeader(code) io.WriteString(w, fmt.Sprintf("%s\n", http.StatusText(code))) }