func generate(generateDir string) {
	dir, err := osutil.ExpandTilde(generateDir)
	if err != nil {
		l.Fatalln("generate:", err)
	}

	info, err := os.Stat(dir)
	if err == nil && !info.IsDir() {
		l.Fatalln(dir, "is not a directory")
	}
	if err != nil && os.IsNotExist(err) {
		err = osutil.MkdirAll(dir, 0700)
		if err != nil {
			l.Fatalln("generate:", err)
		}
	}

	certFile, keyFile := filepath.Join(dir, "cert.pem"), filepath.Join(dir, "key.pem")
	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
	if err == nil {
		l.Warnln("Key exists; will not overwrite.")
		l.Infoln("Device ID:", protocol.NewDeviceID(cert.Certificate[0]))
	} else {
		cert, err = tlsutil.NewCertificate(certFile, keyFile, tlsDefaultCommonName, bepRSABits)
		if err != nil {
			l.Fatalln("Create certificate:", err)
		}
		myID = protocol.NewDeviceID(cert.Certificate[0])
		if err != nil {
			l.Fatalln("Load certificate:", err)
		}
		if err == nil {
			l.Infoln("Device ID:", protocol.NewDeviceID(cert.Certificate[0]))
		}
	}

	cfgFile := filepath.Join(dir, "config.xml")
	if _, err := os.Stat(cfgFile); err == nil {
		l.Warnln("Config exists; will not overwrite.")
		return
	}
	var myName, _ = os.Hostname()
	var newCfg = defaultConfig(myName)
	var cfg = config.Wrap(cfgFile, newCfg)
	err = cfg.Save()
	if err != nil {
		l.Warnln("Failed to save config", err)
	}
}

func TestRelay(uri *url.URL, certs []tls.Certificate, sleep time.Duration, times int) bool {
	id := syncthingprotocol.NewDeviceID(certs[0].Certificate[0])
	invs := make(chan protocol.SessionInvitation, 1)
	c, err := NewClient(uri, certs, invs)
	if err != nil {
		close(invs)
		return false
	}
	go c.Serve()
	defer func() {
		c.Stop()
		close(invs)
	}()

	for i := 0; i < times; i++ {
		_, err := GetInvitationFromRelay(uri, id, certs)
		if err == nil {
			return true
		}
		if !strings.Contains(err.Error(), "Incorrect response code") {
			return false
		}
		time.Sleep(sleep)
	}
	return false
}

func performHandshakeAndValidation(conn *tls.Conn, uri *url.URL) error {
	if err := conn.Handshake(); err != nil {
		return err
	}

	cs := conn.ConnectionState()
	if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != protocol.ProtocolName {
		return fmt.Errorf("protocol negotiation error")
	}

	q := uri.Query()
	relayIDs := q.Get("id")
	if relayIDs != "" {
		relayID, err := syncthingprotocol.DeviceIDFromString(relayIDs)
		if err != nil {
			return fmt.Errorf("relay address contains invalid verification id: %s", err)
		}

		certs := cs.PeerCertificates
		if cl := len(certs); cl != 1 {
			return fmt.Errorf("unexpected certificate count: %d", cl)
		}

		remoteID := syncthingprotocol.NewDeviceID(certs[0].Raw)
		if remoteID != relayID {
			return fmt.Errorf("relay id does not match. Expected %v got %v", relayID, remoteID)
		}
	}

	return nil
}

func (s *querysrv) handlePOST(ctx context.Context, remoteIP net.IP, w http.ResponseWriter, req *http.Request) {
	reqID := ctx.Value("id").(requestID)

	rawCert := certificateBytes(req)
	if rawCert == nil {
		if debug {
			log.Println(reqID, "no certificates")
		}
		globalStats.Error()
		http.Error(w, "Forbidden", http.StatusForbidden)
		return
	}

	var ann announcement
	if err := json.NewDecoder(req.Body).Decode(&ann); err != nil {
		if debug {
			log.Println(reqID, "decode:", err)
		}
		globalStats.Error()
		http.Error(w, "Bad Request", http.StatusBadRequest)
		return
	}

	deviceID := protocol.NewDeviceID(rawCert)

	// handleAnnounce returns *two* errors. The first indicates a problem with
	// something the client posted to us. We should return a 400 Bad Request
	// and not worry about it. The second indicates that the request was fine,
	// but something internal messed up. We should log it and respond with a
	// more apologetic 500 Internal Server Error.
	userErr, internalErr := s.handleAnnounce(ctx, remoteIP, deviceID, ann.Addresses)
	if userErr != nil {
		if debug {
			log.Println(reqID, "handleAnnounce:", userErr)
		}
		globalStats.Error()
		http.Error(w, "Bad Request", http.StatusBadRequest)
		return
	}
	if internalErr != nil {
		log.Println(reqID, "handleAnnounce:", internalErr)
		globalStats.Error()
		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
		return
	}

	globalStats.Announce()

	// TODO: Slowly increase this for stable clients
	w.Header().Set("Reannounce-After", "1800")

	// We could return the lookup result here, but it's kind of unnecessarily
	// expensive to go query the database again so we let the client decide to
	// do a lookup if they really care.
	w.WriteHeader(http.StatusNoContent)
}

func TestManyPeers(t *testing.T) {
	log.Println("Cleaning...")
	err := removeAll("s1", "s2", "h1/index*", "h2/index*")
	if err != nil {
		t.Fatal(err)
	}

	log.Println("Generating files...")
	err = generateFiles("s1", 200, 20, "../LICENSE")
	if err != nil {
		t.Fatal(err)
	}

	receiver := startInstance(t, 2)
	defer checkedStop(t, receiver)

	bs, err := receiver.Get("/rest/system/config")
	if err != nil {
		t.Fatal(err)
	}

	var cfg config.Configuration
	if err := json.Unmarshal(bs, &cfg); err != nil {
		t.Fatal(err)
	}

	for len(cfg.Devices) < 100 {
		bs := make([]byte, 16)
		ReadRand(bs)
		id := protocol.NewDeviceID(bs)
		cfg.Devices = append(cfg.Devices, config.DeviceConfiguration{DeviceID: id})
		cfg.Folders[0].Devices = append(cfg.Folders[0].Devices, config.FolderDeviceConfiguration{DeviceID: id})
	}

	osutil.Rename("h2/config.xml", "h2/config.xml.orig")
	defer osutil.Rename("h2/config.xml.orig", "h2/config.xml")

	var buf bytes.Buffer
	json.NewEncoder(&buf).Encode(cfg)
	_, err = receiver.Post("/rest/system/config", &buf)
	if err != nil {
		t.Fatal(err)
	}

	sender := startInstance(t, 1)
	defer checkedStop(t, sender)

	rc.AwaitSync("default", sender, receiver)

	log.Println("Comparing directories...")
	err = compareDirectories("s1", "s2")
	if err != nil {
		t.Fatal(err)
	}
}

// Try certificates until one is found that has the prefix at the start of
// the resulting device ID. Increments count atomically, sends the result to
// found, returns when stop is closed.
func generatePrefixed(prefix string, count *int64, found chan<- result, stop <-chan struct{}) {
	notBefore := time.Now()
	notAfter := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)

	template := x509.Certificate{
		SerialNumber: new(big.Int).SetInt64(mr.Int63()),
		Subject: pkix.Name{
			CommonName: "syncthing",
		},
		NotBefore: notBefore,
		NotAfter:  notAfter,

		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
		BasicConstraintsValid: true,
	}

	priv, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	for {
		select {
		case <-stop:
			return
		default:
		}

		derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
		if err != nil {
			fmt.Println(err)
			os.Exit(1)
		}

		id := protocol.NewDeviceID(derBytes)
		atomic.AddInt64(count, 1)

		if strings.HasPrefix(id.String(), prefix) {
			select {
			case found <- result{id, priv, derBytes}:
			case <-stop:
			}
			return
		}
	}
}

func (c *idCheckingHTTPClient) check(resp *http.Response) error {
	if resp.TLS == nil {
		return errors.New("security: not TLS")
	}

	if len(resp.TLS.PeerCertificates) == 0 {
		return errors.New("security: no certificates")
	}

	id := protocol.NewDeviceID(resp.TLS.PeerCertificates[0].Raw)
	if !id.Equals(c.id) {
		return errors.New("security: incorrect device id")
	}

	return nil
}

func main() {
	log.SetFlags(log.Lshortfile | log.LstdFlags)

	var dir, extAddress string

	flag.StringVar(&listen, "listen", ":22067", "Protocol listen address")
	flag.StringVar(&dir, "keys", ".", "Directory where cert.pem and key.pem is stored")
	flag.DurationVar(&networkTimeout, "network-timeout", networkTimeout, "Timeout for network operations between the client and the relay.\n\tIf no data is received between the client and the relay in this period of time, the connection is terminated.\n\tFurthermore, if no data is sent between either clients being relayed within this period of time, the session is also terminated.")
	flag.DurationVar(&pingInterval, "ping-interval", pingInterval, "How often pings are sent")
	flag.DurationVar(&messageTimeout, "message-timeout", messageTimeout, "Maximum amount of time we wait for relevant messages to arrive")
	flag.IntVar(&sessionLimitBps, "per-session-rate", sessionLimitBps, "Per session rate limit, in bytes/s")
	flag.IntVar(&globalLimitBps, "global-rate", globalLimitBps, "Global rate limit, in bytes/s")
	flag.BoolVar(&debug, "debug", debug, "Enable debug output")
	flag.StringVar(&statusAddr, "status-srv", ":22070", "Listen address for status service (blank to disable)")
	flag.StringVar(&poolAddrs, "pools", defaultPoolAddrs, "Comma separated list of relay pool addresses to join")
	flag.StringVar(&providedBy, "provided-by", "", "An optional description about who provides the relay")
	flag.StringVar(&extAddress, "ext-address", "", "An optional address to advertising as being available on.\n\tAllows listening on an unprivileged port with port forwarding from e.g. 443, and be connected to on port 443.")

	flag.Parse()

	if extAddress == "" {
		extAddress = listen
	}

	addr, err := net.ResolveTCPAddr("tcp", extAddress)
	if err != nil {
		log.Fatal(err)
	}

	sessionAddress = addr.IP[:]
	sessionPort = uint16(addr.Port)

	certFile, keyFile := filepath.Join(dir, "cert.pem"), filepath.Join(dir, "key.pem")
	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
	if err != nil {
		log.Println("Failed to load keypair. Generating one, this might take a while...")
		cert, err = tlsutil.NewCertificate(certFile, keyFile, "relaysrv", 3072)
		if err != nil {
			log.Fatalln("Failed to generate X509 key pair:", err)
		}
	}

	tlsCfg := &tls.Config{
		Certificates:           []tls.Certificate{cert},
		NextProtos:             []string{protocol.ProtocolName},
		ClientAuth:             tls.RequestClientCert,
		SessionTicketsDisabled: true,
		InsecureSkipVerify:     true,
		MinVersion:             tls.VersionTLS12,
		CipherSuites: []uint16{
			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
			tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
		},
	}

	id := syncthingprotocol.NewDeviceID(cert.Certificate[0])
	if debug {
		log.Println("ID:", id)
	}

	if sessionLimitBps > 0 {
		sessionLimiter = ratelimit.NewBucketWithRate(float64(sessionLimitBps), int64(2*sessionLimitBps))
	}
	if globalLimitBps > 0 {
		globalLimiter = ratelimit.NewBucketWithRate(float64(globalLimitBps), int64(2*globalLimitBps))
	}

	if statusAddr != "" {
		go statusService(statusAddr)
	}

	uri, err := url.Parse(fmt.Sprintf("relay://%s/?id=%s&pingInterval=%s&networkTimeout=%s&sessionLimitBps=%d&globalLimitBps=%d&statusAddr=%s&providedBy=%s", extAddress, id, pingInterval, networkTimeout, sessionLimitBps, globalLimitBps, statusAddr, providedBy))
	if err != nil {
		log.Fatalln("Failed to construct URI", err)
	}

	log.Println("URI:", uri.String())

	if poolAddrs == defaultPoolAddrs {
		log.Println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
		log.Println("!!  Joining default relay pools, this relay will be available for public use. !!")
		log.Println(`!!      Use the -pools="" command line option to make the relay private.      !!`)
		log.Println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
	}

	pools = strings.Split(poolAddrs, ",")
	for _, pool := range pools {
		pool = strings.TrimSpace(pool)
		if len(pool) > 0 {
			go poolHandler(pool, uri)
		}
	}

	listener(listen, tlsCfg)
}

func (s *connectionSvc) handle() {
next:
	for c := range s.conns {
		cs := c.Conn.ConnectionState()

		// We should have negotiated the next level protocol "bep/1.0" as part
		// of the TLS handshake. Unfortunately this can't be a hard error,
		// because there are implementations out there that don't support
		// protocol negotiation (iOS for one...).
		if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != bepProtocolName {
			l.Infof("Peer %s did not negotiate bep/1.0", c.Conn.RemoteAddr())
		}

		// We should have received exactly one certificate from the other
		// side. If we didn't, they don't have a device ID and we drop the
		// connection.
		certs := cs.PeerCertificates
		if cl := len(certs); cl != 1 {
			l.Infof("Got peer certificate list of length %d != 1 from %s; protocol error", cl, c.Conn.RemoteAddr())
			c.Conn.Close()
			continue
		}
		remoteCert := certs[0]
		remoteID := protocol.NewDeviceID(remoteCert.Raw)

		// The device ID should not be that of ourselves. It can happen
		// though, especially in the presence of NAT hairpinning, multiple
		// clients between the same NAT gateway, and global discovery.
		if remoteID == myID {
			l.Infof("Connected to myself (%s) - should not happen", remoteID)
			c.Conn.Close()
			continue
		}

		// If we have a relay connection, and the new incoming connection is
		// not a relay connection, we should drop that, and prefer the this one.
		s.mut.RLock()
		ct, ok := s.connType[remoteID]
		s.mut.RUnlock()
		if ok && !ct.IsDirect() && c.Type.IsDirect() {
			if debugNet {
				l.Debugln("Switching connections", remoteID)
			}
			s.model.Close(remoteID, fmt.Errorf("switching connections"))
		} else if s.model.ConnectedTo(remoteID) {
			// We should not already be connected to the other party. TODO: This
			// could use some better handling. If the old connection is dead but
			// hasn't timed out yet we may want to drop *that* connection and keep
			// this one. But in case we are two devices connecting to each other
			// in parallel we don't want to do that or we end up with no
			// connections still established...
			l.Infof("Connected to already connected device (%s)", remoteID)
			c.Conn.Close()
			continue
		} else if s.model.IsPaused(remoteID) {
			l.Infof("Connection from paused device (%s)", remoteID)
			c.Conn.Close()
			continue
		}

		for deviceID, deviceCfg := range s.cfg.Devices() {
			if deviceID == remoteID {
				// Verify the name on the certificate. By default we set it to
				// "syncthing" when generating, but the user may have replaced
				// the certificate and used another name.
				certName := deviceCfg.CertName
				if certName == "" {
					certName = tlsDefaultCommonName
				}
				err := remoteCert.VerifyHostname(certName)
				if err != nil {
					// Incorrect certificate name is something the user most
					// likely wants to know about, since it's an advanced
					// config. Warn instead of Info.
					l.Warnf("Bad certificate from %s (%v): %v", remoteID, c.Conn.RemoteAddr(), err)
					c.Conn.Close()
					continue next
				}

				// If rate limiting is set, and based on the address we should
				// limit the connection, then we wrap it in a limiter.

				limit := s.shouldLimit(c.Conn.RemoteAddr())

				wr := io.Writer(c.Conn)
				if limit && writeRateLimit != nil {
					wr = &limitedWriter{c.Conn, writeRateLimit}
				}

				rd := io.Reader(c.Conn)
				if limit && readRateLimit != nil {
					rd = &limitedReader{c.Conn, readRateLimit}
				}

				name := fmt.Sprintf("%s-%s (%s)", c.Conn.LocalAddr(), c.Conn.RemoteAddr(), c.Type)
				protoConn := protocol.NewConnection(remoteID, rd, wr, s.model, name, deviceCfg.Compression)

				l.Infof("Established secure connection to %s at %s", remoteID, name)
				if debugNet {
					l.Debugf("cipher suite: %04X in lan: %t", c.Conn.ConnectionState().CipherSuite, !limit)
//.........这里部分代码省略.........

func (s *Service) handle() {
next:
	for c := range s.conns {
		cs := c.ConnectionState()

		// We should have negotiated the next level protocol "bep/1.0" as part
		// of the TLS handshake. Unfortunately this can't be a hard error,
		// because there are implementations out there that don't support
		// protocol negotiation (iOS for one...).
		if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != s.bepProtocolName {
			l.Infof("Peer %s did not negotiate bep/1.0", c.RemoteAddr())
		}

		// We should have received exactly one certificate from the other
		// side. If we didn't, they don't have a device ID and we drop the
		// connection.
		certs := cs.PeerCertificates
		if cl := len(certs); cl != 1 {
			l.Infof("Got peer certificate list of length %d != 1 from %s; protocol error", cl, c.RemoteAddr())
			c.Close()
			continue
		}
		remoteCert := certs[0]
		remoteID := protocol.NewDeviceID(remoteCert.Raw)

		// The device ID should not be that of ourselves. It can happen
		// though, especially in the presence of NAT hairpinning, multiple
		// clients between the same NAT gateway, and global discovery.
		if remoteID == s.myID {
			l.Infof("Connected to myself (%s) - should not happen", remoteID)
			c.Close()
			continue
		}

		c.SetDeadline(time.Now().Add(20 * time.Second))
		hello, err := protocol.ExchangeHello(c, s.model.GetHello(remoteID))
		if err != nil {
			if protocol.IsVersionMismatch(err) {
				// The error will be a relatively user friendly description
				// of what's wrong with the version compatibility
				msg := fmt.Sprintf("Connecting to %s (%s): %s", remoteID, c.RemoteAddr(), err)
				warningFor(remoteID, msg)
			} else {
				// It's something else - connection reset or whatever
				l.Infof("Failed to exchange Hello messages with %s (%s): %s", remoteID, c.RemoteAddr(), err)
			}
			c.Close()
			continue
		}
		c.SetDeadline(time.Time{})

		s.model.OnHello(remoteID, c.RemoteAddr(), hello)

		// If we have a relay connection, and the new incoming connection is
		// not a relay connection, we should drop that, and prefer the this one.
		s.curConMut.Lock()
		ct, ok := s.currentConnection[remoteID]
		s.curConMut.Unlock()

		// Lower priority is better, just like nice etc.
		if ok && ct.Priority > c.Priority {
			l.Debugln("Switching connections", remoteID)
			s.model.Close(remoteID, protocol.ErrSwitchingConnections)
		} else if s.model.ConnectedTo(remoteID) {
			// We should not already be connected to the other party. TODO: This
			// could use some better handling. If the old connection is dead but
			// hasn't timed out yet we may want to drop *that* connection and keep
			// this one. But in case we are two devices connecting to each other
			// in parallel we don't want to do that or we end up with no
			// connections still established...
			l.Infof("Connected to already connected device (%s)", remoteID)
			c.Close()
			continue
		} else if s.model.IsPaused(remoteID) {
			l.Infof("Connection from paused device (%s)", remoteID)
			c.Close()
			continue
		}

		for deviceID, deviceCfg := range s.cfg.Devices() {
			if deviceID == remoteID {
				// Verify the name on the certificate. By default we set it to
				// "syncthing" when generating, but the user may have replaced
				// the certificate and used another name.
				certName := deviceCfg.CertName
				if certName == "" {
					certName = s.tlsDefaultCommonName
				}
				err := remoteCert.VerifyHostname(certName)
				if err != nil {
					// Incorrect certificate name is something the user most
					// likely wants to know about, since it's an advanced
					// config. Warn instead of Info.
					l.Warnf("Bad certificate from %s (%v): %v", remoteID, c.RemoteAddr(), err)
					c.Close()
					continue next
				}

				// If rate limiting is set, and based on the address we should
				// limit the connection, then we wrap it in a limiter.
//.........这里部分代码省略.........

func syncthingMain() {
	// Create a main service manager. We'll add things to this as we go along.
	// We want any logging it does to go through our log system.
	mainSvc := suture.New("main", suture.Spec{
		Log: func(line string) {
			l.Debugln(line)
		},
	})
	mainSvc.ServeBackground()

	// Set a log prefix similar to the ID we will have later on, or early log
	// lines look ugly.
	l.SetPrefix("[start] ")

	if auditEnabled {
		startAuditing(mainSvc)
	}

	if verbose {
		mainSvc.Add(newVerboseSvc())
	}

	errors := logger.NewRecorder(l, logger.LevelWarn, maxSystemErrors, 0)
	systemLog := logger.NewRecorder(l, logger.LevelDebug, maxSystemLog, initialSystemLog)

	// Event subscription for the API; must start early to catch the early events.
	apiSub := events.NewBufferedSubscription(events.Default.Subscribe(events.AllEvents), 1000)

	if len(os.Getenv("GOMAXPROCS")) == 0 {
		runtime.GOMAXPROCS(runtime.NumCPU())
	}

	// Attempt to increase the limit on number of open files to the maximum
	// allowed, in case we have many peers. We don't really care enough to
	// report the error if there is one.
	osutil.MaximizeOpenFileLimit()

	// Ensure that that we have a certificate and key.
	cert, err := tls.LoadX509KeyPair(locations[locCertFile], locations[locKeyFile])
	if err != nil {
		l.Infof("Generating RSA key and certificate for %s...", tlsDefaultCommonName)
		cert, err = tlsutil.NewCertificate(locations[locCertFile], locations[locKeyFile], tlsDefaultCommonName, tlsRSABits)
		if err != nil {
			l.Fatalln(err)
		}
	}

	// We reinitialize the predictable RNG with our device ID, to get a
	// sequence that is always the same but unique to this syncthing instance.
	predictableRandom.Seed(seedFromBytes(cert.Certificate[0]))

	myID = protocol.NewDeviceID(cert.Certificate[0])
	l.SetPrefix(fmt.Sprintf("[%s] ", myID.String()[:5]))

	l.Infoln(LongVersion)
	l.Infoln("My ID:", myID)

	// Emit the Starting event, now that we know who we are.

	events.Default.Log(events.Starting, map[string]string{
		"home": baseDirs["config"],
		"myID": myID.String(),
	})

	// Prepare to be able to save configuration

	cfgFile := locations[locConfigFile]

	// Load the configuration file, if it exists.
	// If it does not, create a template.

	cfg, myName, err := loadConfig(cfgFile)
	if err != nil {
		if os.IsNotExist(err) {
			l.Infoln("No config file; starting with empty defaults")
			myName, _ = os.Hostname()
			newCfg := defaultConfig(myName)
			cfg = config.Wrap(cfgFile, newCfg)
			cfg.Save()
			l.Infof("Edit %s to taste or use the GUI\n", cfgFile)
		} else {
			l.Fatalln("Loading config:", err)
		}
	}

	if cfg.Raw().OriginalVersion != config.CurrentVersion {
		l.Infoln("Archiving a copy of old config file format")
		// Archive a copy
		osutil.Rename(cfgFile, cfgFile+fmt.Sprintf(".v%d", cfg.Raw().OriginalVersion))
		// Save the new version
		cfg.Save()
	}

	if err := checkShortIDs(cfg); err != nil {
		l.Fatalln("Short device IDs are in conflict. Unlucky!\n  Regenerate the device ID of one if the following:\n  ", err)
	}

	if len(profiler) > 0 {
		go func() {
			l.Debugln("Starting profiler on", profiler)
//.........这里部分代码省略.........

func main() {
	if runtime.GOOS == "windows" {
		// On Windows, we use a log file by default. Setting the -logfile flag
		// to "-" disables this behavior.
		flag.StringVar(&logFile, "logfile", "", "Log file name (use \"-\" for stdout)")

		// We also add an option to hide the console window
		flag.BoolVar(&noConsole, "no-console", false, "Hide console window")
	} else {
		flag.StringVar(&logFile, "logfile", "-", "Log file name (use \"-\" for stdout)")
	}

	flag.StringVar(&generateDir, "generate", "", "Generate key and config in specified dir, then exit")
	flag.StringVar(&guiAddress, "gui-address", guiAddress, "Override GUI address")
	flag.StringVar(&guiAPIKey, "gui-apikey", guiAPIKey, "Override GUI API key")
	flag.StringVar(&confDir, "home", "", "Set configuration directory")
	flag.IntVar(&logFlags, "logflags", logFlags, "Select information in log line prefix")
	flag.BoolVar(&noBrowser, "no-browser", false, "Do not start browser")
	flag.BoolVar(&noRestart, "no-restart", noRestart, "Do not restart; just exit")
	flag.BoolVar(&reset, "reset", false, "Reset the database")
	flag.BoolVar(&doUpgrade, "upgrade", false, "Perform upgrade")
	flag.BoolVar(&doUpgradeCheck, "upgrade-check", false, "Check for available upgrade")
	flag.BoolVar(&showVersion, "version", false, "Show version")
	flag.StringVar(&upgradeTo, "upgrade-to", upgradeTo, "Force upgrade directly from specified URL")
	flag.BoolVar(&auditEnabled, "audit", false, "Write events to audit file")
	flag.BoolVar(&verbose, "verbose", false, "Print verbose log output")
	flag.BoolVar(&paused, "paused", false, "Start with all devices paused")

	longUsage := fmt.Sprintf(extraUsage, baseDirs["config"], debugFacilities())
	flag.Usage = usageFor(flag.CommandLine, usage, longUsage)
	flag.Parse()

	if noConsole {
		osutil.HideConsole()
	}

	if confDir != "" {
		// Not set as default above because the string can be really long.
		baseDirs["config"] = confDir
	}

	if err := expandLocations(); err != nil {
		l.Fatalln(err)
	}

	if guiAssets == "" {
		guiAssets = locations[locGUIAssets]
	}

	if logFile == "" {
		// Use the default log file location
		logFile = locations[locLogFile]
	}

	if showVersion {
		fmt.Println(LongVersion)
		return
	}

	l.SetFlags(logFlags)

	if generateDir != "" {
		dir, err := osutil.ExpandTilde(generateDir)
		if err != nil {
			l.Fatalln("generate:", err)
		}

		info, err := os.Stat(dir)
		if err == nil && !info.IsDir() {
			l.Fatalln(dir, "is not a directory")
		}
		if err != nil && os.IsNotExist(err) {
			err = osutil.MkdirAll(dir, 0700)
			if err != nil {
				l.Fatalln("generate:", err)
			}
		}

		certFile, keyFile := filepath.Join(dir, "cert.pem"), filepath.Join(dir, "key.pem")
		cert, err := tls.LoadX509KeyPair(certFile, keyFile)
		if err == nil {
			l.Warnln("Key exists; will not overwrite.")
			l.Infoln("Device ID:", protocol.NewDeviceID(cert.Certificate[0]))
		} else {
			cert, err = tlsutil.NewCertificate(certFile, keyFile, tlsDefaultCommonName, tlsRSABits)
			if err != nil {
				l.Fatalln("Create certificate:", err)
			}
			myID = protocol.NewDeviceID(cert.Certificate[0])
			if err != nil {
				l.Fatalln("Load certificate:", err)
			}
			if err == nil {
				l.Infoln("Device ID:", protocol.NewDeviceID(cert.Certificate[0]))
			}
		}

		cfgFile := filepath.Join(dir, "config.xml")
		if _, err := os.Stat(cfgFile); err == nil {
			l.Warnln("Config exists; will not overwrite.")
//.........这里部分代码省略.........

func main() {
	log.SetFlags(log.Lshortfile | log.LstdFlags)

	var dir, extAddress, proto string

	flag.StringVar(&listen, "listen", ":22067", "Protocol listen address")
	flag.StringVar(&dir, "keys", ".", "Directory where cert.pem and key.pem is stored")
	flag.DurationVar(&networkTimeout, "network-timeout", networkTimeout, "Timeout for network operations between the client and the relay.\n\tIf no data is received between the client and the relay in this period of time, the connection is terminated.\n\tFurthermore, if no data is sent between either clients being relayed within this period of time, the session is also terminated.")
	flag.DurationVar(&pingInterval, "ping-interval", pingInterval, "How often pings are sent")
	flag.DurationVar(&messageTimeout, "message-timeout", messageTimeout, "Maximum amount of time we wait for relevant messages to arrive")
	flag.IntVar(&sessionLimitBps, "per-session-rate", sessionLimitBps, "Per session rate limit, in bytes/s")
	flag.IntVar(&globalLimitBps, "global-rate", globalLimitBps, "Global rate limit, in bytes/s")
	flag.BoolVar(&debug, "debug", debug, "Enable debug output")
	flag.StringVar(&statusAddr, "status-srv", ":22070", "Listen address for status service (blank to disable)")
	flag.StringVar(&poolAddrs, "pools", defaultPoolAddrs, "Comma separated list of relay pool addresses to join")
	flag.StringVar(&providedBy, "provided-by", "", "An optional description about who provides the relay")
	flag.StringVar(&extAddress, "ext-address", "", "An optional address to advertise as being available on.\n\tAllows listening on an unprivileged port with port forwarding from e.g. 443, and be connected to on port 443.")
	flag.StringVar(&proto, "protocol", "tcp", "Protocol used for listening. 'tcp' for IPv4 and IPv6, 'tcp4' for IPv4, 'tcp6' for IPv6")
	flag.BoolVar(&natEnabled, "nat", false, "Use UPnP/NAT-PMP to acquire external port mapping")
	flag.IntVar(&natLease, "nat-lease", 60, "NAT lease length in minutes")
	flag.IntVar(&natRenewal, "nat-renewal", 30, "NAT renewal frequency in minutes")
	flag.IntVar(&natTimeout, "nat-timeout", 10, "NAT discovery timeout in seconds")
	flag.Parse()

	if extAddress == "" {
		extAddress = listen
	}

	if len(providedBy) > 30 {
		log.Fatal("Provided-by cannot be longer than 30 characters")
	}

	addr, err := net.ResolveTCPAddr(proto, extAddress)
	if err != nil {
		log.Fatal(err)
	}

	laddr, err := net.ResolveTCPAddr(proto, listen)
	if err != nil {
		log.Fatal(err)
	}
	if laddr.IP != nil && !laddr.IP.IsUnspecified() {
		laddr.Port = 0
		transport, ok := http.DefaultTransport.(*http.Transport)
		if ok {
			transport.Dial = (&net.Dialer{
				Timeout:   30 * time.Second,
				LocalAddr: laddr,
			}).Dial
		}
	}

	log.Println(LongVersion)

	maxDescriptors, err := osutil.MaximizeOpenFileLimit()
	if maxDescriptors > 0 {
		// Assume that 20% of FD's are leaked/unaccounted for.
		descriptorLimit = int64(maxDescriptors*80) / 100
		log.Println("Connection limit", descriptorLimit)

		go monitorLimits()
	} else if err != nil && runtime.GOOS != "windows" {
		log.Println("Assuming no connection limit, due to error retrieving rlimits:", err)
	}

	sessionAddress = addr.IP[:]
	sessionPort = uint16(addr.Port)

	certFile, keyFile := filepath.Join(dir, "cert.pem"), filepath.Join(dir, "key.pem")
	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
	if err != nil {
		log.Println("Failed to load keypair. Generating one, this might take a while...")
		cert, err = tlsutil.NewCertificate(certFile, keyFile, "strelaysrv", 3072)
		if err != nil {
			log.Fatalln("Failed to generate X509 key pair:", err)
		}
	}

	tlsCfg := &tls.Config{
		Certificates:           []tls.Certificate{cert},
		NextProtos:             []string{protocol.ProtocolName},
		ClientAuth:             tls.RequestClientCert,
		SessionTicketsDisabled: true,
		InsecureSkipVerify:     true,
		MinVersion:             tls.VersionTLS12,
		CipherSuites: []uint16{
			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
			tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
		},
	}

	id := syncthingprotocol.NewDeviceID(cert.Certificate[0])
	if debug {
		log.Println("ID:", id)
	}

//.........这里部分代码省略.........

func main() {
	log.SetOutput(os.Stdout)
	log.SetFlags(log.LstdFlags | log.Lshortfile)

	var connect, relay, dir string
	var join, test bool

	flag.StringVar(&connect, "connect", "", "Device ID to which to connect to")
	flag.BoolVar(&join, "join", false, "Join relay")
	flag.BoolVar(&test, "test", false, "Generic relay test")
	flag.StringVar(&relay, "relay", "relay://127.0.0.1:22067", "Relay address")
	flag.StringVar(&dir, "keys", ".", "Directory where cert.pem and key.pem is stored")

	flag.Parse()

	certFile, keyFile := filepath.Join(dir, "cert.pem"), filepath.Join(dir, "key.pem")
	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
	if err != nil {
		log.Fatalln("Failed to load X509 key pair:", err)
	}

	id := syncthingprotocol.NewDeviceID(cert.Certificate[0])
	log.Println("ID:", id)

	uri, err := url.Parse(relay)
	if err != nil {
		log.Fatal(err)
	}

	stdin := make(chan string)

	go stdinReader(stdin)

	if join {
		log.Println("Creating client")
		relay, err := client.NewClient(uri, []tls.Certificate{cert}, nil, 10*time.Second)
		if err != nil {
			log.Fatal(err)
		}
		log.Println("Created client")

		go relay.Serve()

		recv := make(chan protocol.SessionInvitation)

		go func() {
			log.Println("Starting invitation receiver")
			for invite := range relay.Invitations() {
				select {
				case recv <- invite:
					log.Println("Received invitation", invite)
				default:
					log.Println("Discarding invitation", invite)
				}
			}
		}()

		for {
			conn, err := client.JoinSession(<-recv)
			if err != nil {
				log.Fatalln("Failed to join", err)
			}
			log.Println("Joined", conn.RemoteAddr(), conn.LocalAddr())
			connectToStdio(stdin, conn)
			log.Println("Finished", conn.RemoteAddr(), conn.LocalAddr())
		}
	} else if connect != "" {
		id, err := syncthingprotocol.DeviceIDFromString(connect)
		if err != nil {
			log.Fatal(err)
		}

		invite, err := client.GetInvitationFromRelay(uri, id, []tls.Certificate{cert}, 10*time.Second)
		if err != nil {
			log.Fatal(err)
		}

		log.Println("Received invitation", invite)
		conn, err := client.JoinSession(invite)
		if err != nil {
			log.Fatalln("Failed to join", err)
		}
		log.Println("Joined", conn.RemoteAddr(), conn.LocalAddr())
		connectToStdio(stdin, conn)
		log.Println("Finished", conn.RemoteAddr(), conn.LocalAddr())
	} else if test {
		if client.TestRelay(uri, []tls.Certificate{cert}, time.Second, 2*time.Second, 4) {
			log.Println("OK")
		} else {
			log.Println("FAIL")
		}
	} else {
		log.Fatal("Requires either join or connect")
	}
}

func main() {
	flag.BoolVar(&showVersion, "version", false, "Show version")

	flag.Usage = usageFor(flag.CommandLine, usage, fmt.Sprintf(extraUsage, baseDirs["config"]))
	flag.Parse()

	if showVersion {
		fmt.Println(Version)
		return
	}

	if err := expandLocations(); err != nil {
		l.Fatalln(err)
	}

	// Ensure that our home directory exists.
	ensureDir(baseDirs["config"], 0700)

	// Ensure that that we have a certificate and key.
	tlsCfg, cert := getTlsConfig()

	// We reinitialize the predictable RNG with our device ID, to get a
	// sequence that is always the same but unique to this syncthing instance.
	predictableRandom.Seed(seedFromBytes(cert.Certificate[0]))

	myID = protocol.NewDeviceID(cert.Certificate[0])
	l.SetPrefix(fmt.Sprintf("[%s] ", myID.String()[:5]))

	l.Infoln("Started syncthingfuse v.", LongVersion)
	l.Infoln("My ID:", myID)

	cfg := getConfiguration()

	if info, err := os.Stat(cfg.Raw().MountPoint); err == nil {
		if !info.Mode().IsDir() {
			l.Fatalln("Mount point (", cfg.Raw().MountPoint, ") must be a directory, but isn't")
			os.Exit(1)
		}
	} else {
		l.Infoln("Mount point (", cfg.Raw().MountPoint, ") does not exist, creating it")
		err = os.MkdirAll(cfg.Raw().MountPoint, 0700)
		if err != nil {
			l.Fatalln("Error creating mount point", cfg.Raw().MountPoint, err)
			os.Exit(1)
		}
	}

	mainSvc := suture.New("main", suture.Spec{
		Log: func(line string) {
			l.Debugln(line)
		},
	})
	mainSvc.ServeBackground()

	database := openDatabase(cfg)

	m = model.NewModel(cfg, database)

	cachedDiscovery := startDiscovery()
	mainSvc.Add(cachedDiscovery)

	lans, _ := osutil.GetLans()

	connectionSvc := connections.NewConnectionSvc(cfg.AsStCfg(myID), myID, m, tlsCfg, cachedDiscovery, nil /* TODO relaySvc */, bepProtocolName, tlsDefaultCommonName, lans)
	mainSvc.Add(connectionSvc)

	l.Infoln("Started ...")

	MountFuse(cfg.Raw().MountPoint, m) // TODO handle fight between FUSE and Syncthing Service

	mainSvc.Stop()
	l.Okln("Exiting")

	return
}

func main() {
	flag.BoolVar(&showVersion, "version", false, "Show version")

	flag.Usage = usageFor(flag.CommandLine, usage, fmt.Sprintf(extraUsage, baseDirs["config"]))
	flag.Parse()

	if showVersion {
		fmt.Println(Version)
		return
	}

	if err := expandLocations(); err != nil {
		l.Fatalln(err)
	}

	// Ensure that our home directory exists.
	ensureDir(baseDirs["config"], 0700)

	// Ensure that that we have a certificate and key.
	tlsCfg, cert := getTlsConfig()

	// We reinitialize the predictable RNG with our device ID, to get a
	// sequence that is always the same but unique to this syncthing instance.
	predictableRandom.Seed(seedFromBytes(cert.Certificate[0]))

	myID = protocol.NewDeviceID(cert.Certificate[0])
	l.SetPrefix(fmt.Sprintf("[%s] ", myID.String()[:5]))

	l.Infoln("Started syncthingfuse v.", LongVersion)
	l.Infoln("My ID:", myID)

	cfg := getConfiguration()

	if info, err := os.Stat(cfg.Raw().MountPoint); err == nil {
		if !info.Mode().IsDir() {
			l.Fatalln("Mount point (", cfg.Raw().MountPoint, ") must be a directory, but isn't")
			os.Exit(1)
		}
	} else {
		l.Infoln("Mount point (", cfg.Raw().MountPoint, ") does not exist, creating it")
		err = os.MkdirAll(cfg.Raw().MountPoint, 0700)
		if err != nil {
			l.Warnln("Error creating mount point", cfg.Raw().MountPoint, err)
			l.Warnln("Sometimes, SyncthingFUSE doesn't shut down and unmount cleanly,")
			l.Warnln("If you don't know of any other file systems you have mounted at")
			l.Warnln("the mount point, try running the command below to unmount, then")
			l.Warnln("start SyncthingFUSE again.")
			l.Warnln("    umount", cfg.Raw().MountPoint)
			l.Fatalln("Cannot create missing mount point")
			os.Exit(1)
		}
	}

	mainSvc := suture.New("main", suture.Spec{
		Log: func(line string) {
			l.Debugln(line)
		},
	})
	mainSvc.ServeBackground()

	database := openDatabase(cfg)

	m = model.NewModel(cfg, database)

	lans, _ := osutil.GetLans()

	// Start discovery
	cachedDiscovery := discover.NewCachingMux()
	mainSvc.Add(cachedDiscovery)

	// Start connection management
	connectionsService := connections.NewService(cfg.AsStCfg(myID), myID, m, tlsCfg, cachedDiscovery, bepProtocolName, tlsDefaultCommonName, lans)
	mainSvc.Add(connectionsService)

	if cfg.Raw().Options.GlobalAnnounceEnabled {
		for _, srv := range cfg.Raw().Options.GlobalAnnounceServers {
			l.Infoln("Using discovery server", srv)
			gd, err := discover.NewGlobal(srv, cert, connectionsService)
			if err != nil {
				l.Warnln("Global discovery:", err)
				continue
			}

			// Each global discovery server gets its results cached for five
			// minutes, and is not asked again for a minute when it's returned
			// unsuccessfully.
			cachedDiscovery.Add(gd, 5*time.Minute, time.Minute, globalDiscoveryPriority)
		}
	}

	if cfg.Raw().Options.LocalAnnounceEnabled {
		// v4 broadcasts
		bcd, err := discover.NewLocal(myID, fmt.Sprintf(":%d", cfg.Raw().Options.LocalAnnouncePort), connectionsService)
		if err != nil {
			l.Warnln("IPv4 local discovery:", err)
		} else {
			cachedDiscovery.Add(bcd, 0, 0, ipv4LocalDiscoveryPriority)
		}
		// v6 multicasts
		mcd, err := discover.NewLocal(myID, cfg.Raw().Options.LocalAnnounceMCAddr, connectionsService)
//.........这里部分代码省略.........