core: Clean up network implementation

backend/rpc.go

@@ -25,24 +25,25 @@ func (core *RicochetCore) GetServerStatus(ctx context.Context, req *rpc.ServerSt
 }
 
 func (core *RicochetCore) MonitorNetwork(req *rpc.MonitorNetworkRequest, stream rpc.RicochetCore_MonitorNetworkServer) error {
-	status := &rpc.NetworkStatus{
-		Control: &rpc.TorControlStatus{
-			Status:       rpc.TorControlStatus_ERROR,
-			ErrorMessage: "Not implemented",
-		},
-	}
-
 	events := core.Network.EventMonitor().Subscribe(20)
 	defer core.Network.EventMonitor().Unsubscribe(events)
 
+	// Send initial status event
+	{
+		event := core.Network.GetStatus()
+		if err := stream.Send(&event); err != nil {
+			return err
+		}
+	}
+
 	for {
-		event, ok := (<-events).(bool)
+		event, ok := (<-events).(rpc.NetworkStatus)
 		if !ok {
 			break
 		}
 
 		log.Printf("RPC monitor event: %v", event)
-		if err := stream.Send(status); err != nil {
+		if err := stream.Send(&event); err != nil {
 			return err
 		}
 	}
@@ -58,15 +59,12 @@ func (core *RicochetCore) StartNetwork(ctx context.Context, req *rpc.StartNetwor
 		return nil, err
 	}
 
-	// XXX real status
-	return &rpc.NetworkStatus{
-		Control: &rpc.TorControlStatus{
-			Status: rpc.TorControlStatus_CONNECTED,
-		},
-	}, nil
+	status := core.Network.GetStatus()
+	return &status, nil
 }
 
 func (core *RicochetCore) StopNetwork(ctx context.Context, req *rpc.StopNetworkRequest) (*rpc.NetworkStatus, error) {
 	core.Network.Stop()
-	return &rpc.NetworkStatus{}, nil
+	status := core.Network.GetStatus()
+	return &status, nil
 }

core/network.go

@@ -3,6 +3,7 @@ package core
 import (
 	"errors"
 	"github.com/special/notricochet/core/utils"
+	"github.com/special/notricochet/rpc"
 	"github.com/yawning/bulb"
 	bulbutils "github.com/yawning/bulb/utils"
 	"log"
@@ -11,15 +12,29 @@ import (
 )
 
 type Network struct {
-	conn *bulb.Conn
-
+	// Connection settings; can only change while stopped
 	controlAddress  string
 	controlPassword string
 
-	handleLock  sync.Mutex
-	stopChannel chan struct{}
-
+	// Events
 	events *utils.Publisher
+
+	// nil when stopped, otherwise used to signal stop to active network
+	stopSignal    chan struct{}
+	stoppedSignal chan struct{}
+
+	// Mutex required to access below
+	controlMutex sync.Mutex
+
+	// Do not use while holding controlMutex; instead, copy ptr and unlock
+	// mutex before use.
+	conn *bulb.Conn
+
+	// Modifications must be done while holding controlMutex and signalled
+	// to events. Do not directly modify the child elements, as they are
+	// pointers and may be shared. Instead, construct a new TorControlStatus
+	// et al for each change.
+	status ricochet.NetworkStatus
 }
 
 func CreateNetwork() *Network {
@@ -34,20 +49,20 @@ func CreateNetwork() *Network {
 // been started; if true, the connection is up even if the first attempt failed.
 // The second return value is the connection attempt error, or nil on success.
 func (n *Network) Start(address, password string) (bool, error) {
-	n.handleLock.Lock()
-	defer n.handleLock.Unlock()
-
-	if n.stopChannel != nil {
+	n.controlMutex.Lock()
+	if n.stoppedSignal != nil {
 		// This is an error, because address/password might not be the same
+		n.controlMutex.Unlock()
 		return false, errors.New("Network is already started")
 	}
 
-	n.stopChannel = make(chan struct{})
+	n.stopSignal = make(chan struct{})
+	n.stoppedSignal = make(chan struct{})
 	n.controlAddress = address
 	n.controlPassword = password
+	n.controlMutex.Unlock()
 
 	connectChannel := make(chan error)
-
 	go n.run(connectChannel)
 	err := <-connectChannel
 	return true, err
@@ -58,81 +73,166 @@ func (n *Network) Start(address, password string) (bool, error) {
 // the client will be offline until Start is called again. This call will
 // block until the connection is stopped.
 func (n *Network) Stop() {
-	n.handleLock.Lock()
-	defer n.handleLock.Unlock()
+	// Take mutex, copy channels, nil stopSignal to avoid race if Stop()
+	// is called again. Other calls will still use stoppedSignal.
+	n.controlMutex.Lock()
+	stop := n.stopSignal
+	stopped := n.stoppedSignal
+	n.stopSignal = nil
+	n.controlMutex.Unlock()
 
-	if n.stopChannel == nil {
+	if stop != nil {
+		// Signal to stop
+		stop <- struct{}{}
+	} else if stopped == nil {
+		// Already stopped
 		return
 	}
 
-	// XXX but if we do block that long, we can hold the mutex a _long_ time.
-	// XXX so the mutex won't be suitable for a "is network started" check
-	n.stopChannel <- struct{}{}
-	n.stopChannel = nil
-	n.conn = nil
-	n.controlAddress = ""
-	n.controlPassword = ""
+	// Wait until stopped; safe for multiple receivers, because the channel
+	// is closed on stop. Sender is responsible for all other cleanup and state.
+	<-stopped
 }
 
 func (n *Network) EventMonitor() utils.Subscribable {
 	return n.events
 }
 
+func (n *Network) GetStatus() ricochet.NetworkStatus {
+	n.controlMutex.Lock()
+	status := n.status
+	n.controlMutex.Unlock()
+	return status
+}
+
 func (n *Network) run(connectChannel chan<- error) {
-	var conn *bulb.Conn
-	var err error
+	n.controlMutex.Lock()
+	stopSignal := n.stopSignal
+	stoppedSignal := n.stoppedSignal
+	n.controlMutex.Unlock()
 
 	for {
-		conn, err = createConnection(n.controlAddress, n.controlPassword)
+		// Status to CONNECTING
+		n.controlMutex.Lock()
+		n.status.Control = &ricochet.TorControlStatus{
+			Status: ricochet.TorControlStatus_CONNECTING,
+		}
+		n.status.Connection = &ricochet.TorConnectionStatus{}
+		status := n.status
+		n.controlMutex.Unlock()
+		n.events.Publish(status)
+
+		// Attempt connection
+		conn, err := createConnection(n.controlAddress, n.controlPassword)
 
 		// Report result of the first connection attempt
+		// XXX too early, because of post-connection work
 		if connectChannel != nil {
 			connectChannel <- err
 			close(connectChannel)
 			connectChannel = nil
 		}
 
-		retryChannel := make(chan struct{}, 1)
+		retryChannel := make(chan error, 1)
 
 		if err == nil {
-			// Success! Set connection, handle events, and retry connection
-			// if it fails
+			// Connected successfully; spawn goroutine to poll and handle
+			// control events. On connection failure (or close as a result of
+			// stop), signal retryChannel.
+
+			// XXX TODO: post-connect queries
+
+			// Status to CONNECTED
+			n.controlMutex.Lock()
 			n.conn = conn
-			n.events.Publish(true)
+			n.status.Control = &ricochet.TorControlStatus{
+				Status:     ricochet.TorControlStatus_CONNECTED,
+				TorVersion: "XXX", // XXX
+			}
+			// XXX Fake connection status
+			n.status.Connection = &ricochet.TorConnectionStatus{
+				Status: ricochet.TorConnectionStatus_READY,
+			}
+			status := n.status
+			n.controlMutex.Unlock()
+			n.events.Publish(status)
+
 			go func() {
 				for {
 					event, err := conn.NextEvent()
 					if err != nil {
 						log.Printf("Control connection failed: %v", err)
-						n.events.Publish(false)
-						retryChannel <- struct{}{}
+						retryChannel <- err
 						break
 					}
+					// XXX handle event
 					log.Printf("Control event: %v", event)
 				}
 			}()
 		} else {
-			// Failed; retry in one second
+			// Status to ERROR
+			n.controlMutex.Lock()
+			n.status.Control = &ricochet.TorControlStatus{
+				Status:       ricochet.TorControlStatus_ERROR,
+				ErrorMessage: err.Error(),
+			}
+			n.status.Connection = &ricochet.TorConnectionStatus{}
+			status := n.status
+			n.controlMutex.Unlock()
+			n.events.Publish(status)
+
+			// signal for retry in 5 seconds
 			go func() {
-				time.Sleep(1 * time.Second)
-				retryChannel <- struct{}{}
+				time.Sleep(5 * time.Second)
+				retryChannel <- err
 			}()
 		}
 
+		// Wait for network stop, connection failure, or retry timeout
 		select {
-		case <-n.stopChannel:
-			break
-		case <-retryChannel:
+		case <-stopSignal:
+			// Clean up struct
+			n.controlMutex.Lock()
+			n.controlAddress = ""
+			n.controlPassword = ""
+			n.conn = nil
+			n.stoppedSignal = nil
+			n.status = ricochet.NetworkStatus{}
+			n.controlMutex.Unlock()
+			n.events.Publish(ricochet.NetworkStatus{})
+
+			// Close connection
 			if conn != nil {
 				conn.Close()
 			}
-		}
-	}
 
-	// Stopped
+			// Signal stopped and exit
+			close(stoppedSignal)
+			return
+		case err := <-retryChannel:
+			if err == nil {
+				err = errors.New("Unknown error")
+			}
+
+			// Clean up connection if necessary
 			if conn != nil {
+				// Status to ERROR
+				n.controlMutex.Lock()
+				n.conn = nil
+				n.status.Control = &ricochet.TorControlStatus{
+					Status:       ricochet.TorControlStatus_ERROR,
+					ErrorMessage: err.Error(),
+				}
+				n.status.Connection = &ricochet.TorConnectionStatus{}
+				status := n.status
+				n.controlMutex.Unlock()
+				n.events.Publish(status)
+
 				conn.Close()
 			}
+			// Loop to retry connection
+		}
+	}
 }
 
 func createConnection(address, password string) (*bulb.Conn, error) {