package origin import ( "context" "errors" "fmt" "net" "time" "github.com/cloudflare/cloudflared/connection" "github.com/cloudflare/cloudflared/edgediscovery" "github.com/cloudflare/cloudflared/h2mux" "github.com/cloudflare/cloudflared/signal" tunnelpogs "github.com/cloudflare/cloudflared/tunnelrpc/pogs" "github.com/google/uuid" "github.com/rs/zerolog" ) const ( // SRV and TXT record resolution TTL ResolveTTL = time.Hour // Waiting time before retrying a failed tunnel connection tunnelRetryDuration = time.Second * 10 // Interval between registering new tunnels registrationInterval = time.Second subsystemRefreshAuth = "refresh_auth" // Maximum exponent for 'Authenticate' exponential backoff refreshAuthMaxBackoff = 10 // Waiting time before retrying a failed 'Authenticate' connection refreshAuthRetryDuration = time.Second * 10 // Maximum time to make an Authenticate RPC authTokenTimeout = time.Second * 30 ) var ( errEventDigestUnset = errors.New("event digest unset") ) // Supervisor manages non-declarative tunnels. Establishes TCP connections with the edge, and // reconnects them if they disconnect. type Supervisor struct { cloudflaredUUID uuid.UUID config *TunnelConfig edgeIPs *edgediscovery.Edge tunnelErrors chan tunnelError tunnelsConnecting map[int]chan struct{} // nextConnectedIndex and nextConnectedSignal are used to wait for all // currently-connecting tunnels to finish connecting so we can reset backoff timer nextConnectedIndex int nextConnectedSignal chan struct{} log *zerolog.Logger reconnectCredentialManager *reconnectCredentialManager useReconnectToken bool reconnectCh chan ReconnectSignal gracefulShutdownC chan struct{} } type tunnelError struct { index int addr *net.TCPAddr err error } func NewSupervisor(config *TunnelConfig, reconnectCh chan ReconnectSignal, gracefulShutdownC chan struct{}) (*Supervisor, error) { cloudflaredUUID, err := uuid.NewRandom() if err != nil { return nil, fmt.Errorf("failed to generate cloudflared instance ID: %w", err) } var edgeIPs *edgediscovery.Edge if len(config.EdgeAddrs) > 0 { edgeIPs, err = edgediscovery.StaticEdge(config.Log, config.EdgeAddrs) } else { edgeIPs, err = edgediscovery.ResolveEdge(config.Log) } if err != nil { return nil, err } useReconnectToken := false if config.ClassicTunnel != nil { useReconnectToken = config.ClassicTunnel.UseReconnectToken } return &Supervisor{ cloudflaredUUID: cloudflaredUUID, config: config, edgeIPs: edgeIPs, tunnelErrors: make(chan tunnelError), tunnelsConnecting: map[int]chan struct{}{}, log: config.Log, reconnectCredentialManager: newReconnectCredentialManager(connection.MetricsNamespace, connection.TunnelSubsystem, config.HAConnections), useReconnectToken: useReconnectToken, reconnectCh: reconnectCh, gracefulShutdownC: gracefulShutdownC, }, nil } func (s *Supervisor) Run( ctx context.Context, connectedSignal *signal.Signal, ) error { if err := s.initialize(ctx, connectedSignal); err != nil { return err } var tunnelsWaiting []int tunnelsActive := s.config.HAConnections backoff := BackoffHandler{MaxRetries: s.config.Retries, BaseTime: tunnelRetryDuration, RetryForever: true} var backoffTimer <-chan time.Time refreshAuthBackoff := &BackoffHandler{MaxRetries: refreshAuthMaxBackoff, BaseTime: refreshAuthRetryDuration, RetryForever: true} var refreshAuthBackoffTimer <-chan time.Time if s.useReconnectToken { if timer, err := s.reconnectCredentialManager.RefreshAuth(ctx, refreshAuthBackoff, s.authenticate); err == nil { refreshAuthBackoffTimer = timer } else { s.log.Err(err). Dur("refreshAuthRetryDuration", refreshAuthRetryDuration). Msgf("supervisor: initial refreshAuth failed, retrying in %v", refreshAuthRetryDuration) refreshAuthBackoffTimer = time.After(refreshAuthRetryDuration) } } for { select { // Context cancelled case <-ctx.Done(): for tunnelsActive > 0 { <-s.tunnelErrors tunnelsActive-- } return nil // startTunnel returned with error // (note that this may also be caused by context cancellation) case tunnelError := <-s.tunnelErrors: tunnelsActive-- if tunnelError.err != nil { s.log.Err(tunnelError.err).Int(connection.LogFieldConnIndex, tunnelError.index).Msg("Connection terminated") tunnelsWaiting = append(tunnelsWaiting, tunnelError.index) s.waitForNextTunnel(tunnelError.index) if backoffTimer == nil { backoffTimer = backoff.BackoffTimer() } // Previously we'd mark the edge address as bad here, but now we'll just silently use another. } else if tunnelsActive == 0 { // all connected tunnels exited gracefully, no more work to do return nil } // Backoff was set and its timer expired case <-backoffTimer: backoffTimer = nil for _, index := range tunnelsWaiting { go s.startTunnel(ctx, index, s.newConnectedTunnelSignal(index)) } tunnelsActive += len(tunnelsWaiting) tunnelsWaiting = nil // Time to call Authenticate case <-refreshAuthBackoffTimer: newTimer, err := s.reconnectCredentialManager.RefreshAuth(ctx, refreshAuthBackoff, s.authenticate) if err != nil { s.log.Err(err).Msg("supervisor: Authentication failed") // Permanent failure. Leave the `select` without setting the // channel to be non-null, so we'll never hit this case of the `select` again. continue } refreshAuthBackoffTimer = newTimer // Tunnel successfully connected case <-s.nextConnectedSignal: if !s.waitForNextTunnel(s.nextConnectedIndex) && len(tunnelsWaiting) == 0 { // No more tunnels outstanding, clear backoff timer backoff.SetGracePeriod() } } } } // Returns nil if initialization succeeded, else the initialization error. func (s *Supervisor) initialize( ctx context.Context, connectedSignal *signal.Signal, ) error { availableAddrs := s.edgeIPs.AvailableAddrs() if s.config.HAConnections > availableAddrs { s.log.Info().Msgf("You requested %d HA connections but I can give you at most %d.", s.config.HAConnections, availableAddrs) s.config.HAConnections = availableAddrs } go s.startFirstTunnel(ctx, connectedSignal) select { case <-ctx.Done(): <-s.tunnelErrors return ctx.Err() case tunnelError := <-s.tunnelErrors: return tunnelError.err case <-connectedSignal.Wait(): } // At least one successful connection, so start the rest for i := 1; i < s.config.HAConnections; i++ { ch := signal.New(make(chan struct{})) go s.startTunnel(ctx, i, ch) time.Sleep(registrationInterval) } return nil } // startTunnel starts the first tunnel connection. The resulting error will be sent on // s.tunnelErrors. It will send a signal via connectedSignal if registration succeed func (s *Supervisor) startFirstTunnel( ctx context.Context, connectedSignal *signal.Signal, ) { var ( addr *net.TCPAddr err error ) const firstConnIndex = 0 defer func() { s.tunnelErrors <- tunnelError{index: firstConnIndex, addr: addr, err: err} }() addr, err = s.edgeIPs.GetAddr(firstConnIndex) if err != nil { return } err = ServeTunnelLoop( ctx, s.reconnectCredentialManager, s.config, addr, firstConnIndex, connectedSignal, s.cloudflaredUUID, s.reconnectCh, s.gracefulShutdownC, ) // If the first tunnel disconnects, keep restarting it. edgeErrors := 0 for s.unusedIPs() { if ctx.Err() != nil { return } switch err.(type) { case nil: return // try the next address if it was a dialError(network problem) or // dupConnRegisterTunnelError case edgediscovery.DialError, connection.DupConnRegisterTunnelError: edgeErrors++ default: return } if edgeErrors >= 2 { addr, err = s.edgeIPs.GetDifferentAddr(firstConnIndex) if err != nil { return } } err = ServeTunnelLoop( ctx, s.reconnectCredentialManager, s.config, addr, firstConnIndex, connectedSignal, s.cloudflaredUUID, s.reconnectCh, s.gracefulShutdownC, ) } } // startTunnel starts a new tunnel connection. The resulting error will be sent on // s.tunnelErrors. func (s *Supervisor) startTunnel( ctx context.Context, index int, connectedSignal *signal.Signal, ) { var ( addr *net.TCPAddr err error ) defer func() { s.tunnelErrors <- tunnelError{index: index, addr: addr, err: err} }() addr, err = s.edgeIPs.GetDifferentAddr(index) if err != nil { return } err = ServeTunnelLoop( ctx, s.reconnectCredentialManager, s.config, addr, uint8(index), connectedSignal, s.cloudflaredUUID, s.reconnectCh, s.gracefulShutdownC, ) } func (s *Supervisor) newConnectedTunnelSignal(index int) *signal.Signal { sig := make(chan struct{}) s.tunnelsConnecting[index] = sig s.nextConnectedSignal = sig s.nextConnectedIndex = index return signal.New(sig) } func (s *Supervisor) waitForNextTunnel(index int) bool { delete(s.tunnelsConnecting, index) s.nextConnectedSignal = nil for k, v := range s.tunnelsConnecting { s.nextConnectedIndex = k s.nextConnectedSignal = v return true } return false } func (s *Supervisor) unusedIPs() bool { return s.edgeIPs.AvailableAddrs() > s.config.HAConnections } func (s *Supervisor) authenticate(ctx context.Context, numPreviousAttempts int) (tunnelpogs.AuthOutcome, error) { arbitraryEdgeIP, err := s.edgeIPs.GetAddrForRPC() if err != nil { return nil, err } edgeConn, err := edgediscovery.DialEdge(ctx, dialTimeout, s.config.EdgeTLSConfigs[connection.H2mux], arbitraryEdgeIP) if err != nil { return nil, err } defer edgeConn.Close() handler := h2mux.MuxedStreamFunc(func(*h2mux.MuxedStream) error { // This callback is invoked by h2mux when the edge initiates a stream. return nil // noop }) muxerConfig := s.config.MuxerConfig.H2MuxerConfig(handler, s.log) muxer, err := h2mux.Handshake(edgeConn, edgeConn, *muxerConfig, h2mux.ActiveStreams) if err != nil { return nil, err } go muxer.Serve(ctx) defer func() { // If we don't wait for the muxer shutdown here, edgeConn.Close() runs before the muxer connections are done, // and the user sees log noise: "error writing data", "connection closed unexpectedly" <-muxer.Shutdown() }() stream, err := muxer.OpenRPCStream(ctx) if err != nil { return nil, err } rpcClient := connection.NewTunnelServerClient(ctx, stream, s.log) defer rpcClient.Close() const arbitraryConnectionID = uint8(0) registrationOptions := s.config.RegistrationOptions(arbitraryConnectionID, edgeConn.LocalAddr().String(), s.cloudflaredUUID) registrationOptions.NumPreviousAttempts = uint8(numPreviousAttempts) return rpcClient.Authenticate(ctx, s.config.ClassicTunnel, registrationOptions) }