refactor signal client sync func (#147)

* refactor: move goroutine that runs Signal Client Receive to the engine for better control

* chore: fix comments typo

* test: fix golint

* chore: comments update

* chore: consider connection state=READY in signal and management clients

* chore: fix typos

* test: fix signal ping-pong test

* chore: add wait condition to signal client

* refactor: add stream status to the Signal client

* refactor: defer mutex unlock

client/internal/engine.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"fmt"
 	"github.com/cenkalti/backoff/v4"
-	ice "github.com/pion/ice/v2"
+	"github.com/pion/ice/v2"
 	log "github.com/sirupsen/logrus"
 	"github.com/wiretrustee/wiretrustee/iface"
 	mgm "github.com/wiretrustee/wiretrustee/management/client"
@@ -142,7 +142,7 @@ func (e *Engine) initializePeer(peer Peer) {
 		RandomizationFactor: backoff.DefaultRandomizationFactor,
 		Multiplier:          backoff.DefaultMultiplier,
 		MaxInterval:         5 * time.Second,
-		MaxElapsedTime:      time.Duration(0), //never stop
+		MaxElapsedTime:      0, //never stop
 		Stop:                backoff.Stop,
 		Clock:               backoff.SystemClock,
 	}, e.ctx)
@@ -157,8 +157,7 @@ func (e *Engine) initializePeer(peer Peer) {
 		}
 
 		if err != nil {
-			log.Warnln(err)
+			log.Infof("retrying connection because of error: %s", err.Error())
-			log.Debugf("retrying connection because of error: %s", err.Error())
 			return err
 		}
 		return nil
@@ -332,6 +331,8 @@ func (e *Engine) receiveManagementEvents() {
 			return nil
 		})
 		if err != nil {
+			// happens if management is unavailable for a long time.
+			// We want to cancel the operation of the whole client
 			e.cancel()
 			return
 		}
@@ -414,68 +415,77 @@ func (e *Engine) updatePeers(remotePeers []*mgmProto.RemotePeerConfig) error {
 
 // receiveSignalEvents connects to the Signal Service event stream to negotiate connection with remote peers
 func (e *Engine) receiveSignalEvents() {
-	// connect to a stream of messages coming from the signal server
-	e.signal.Receive(func(msg *sProto.Message) error {
 
-		e.syncMsgMux.Lock()
+	go func() {
-		defer e.syncMsgMux.Unlock()
+		// connect to a stream of messages coming from the signal server
+		err := e.signal.Receive(func(msg *sProto.Message) error {
 
-		conn := e.conns[msg.Key]
+			e.syncMsgMux.Lock()
-		if conn == nil {
+			defer e.syncMsgMux.Unlock()
-			return fmt.Errorf("wrongly addressed message %s", msg.Key)
-		}
 
-		if conn.Config.RemoteWgKey.String() != msg.Key {
+			conn := e.conns[msg.Key]
-			return fmt.Errorf("unknown peer %s", msg.Key)
+			if conn == nil {
-		}
+				return fmt.Errorf("wrongly addressed message %s", msg.Key)
-
-		switch msg.GetBody().Type {
-		case sProto.Body_OFFER:
-			remoteCred, err := signal.UnMarshalCredential(msg)
-			if err != nil {
-				return err
 			}
-			err = conn.OnOffer(IceCredentials{
-				uFrag: remoteCred.UFrag,
-				pwd:   remoteCred.Pwd,
-			})
 
-			if err != nil {
+			if conn.Config.RemoteWgKey.String() != msg.Key {
-				return err
+				return fmt.Errorf("unknown peer %s", msg.Key)
+			}
+
+			switch msg.GetBody().Type {
+			case sProto.Body_OFFER:
+				remoteCred, err := signal.UnMarshalCredential(msg)
+				if err != nil {
+					return err
+				}
+				err = conn.OnOffer(IceCredentials{
+					uFrag: remoteCred.UFrag,
+					pwd:   remoteCred.Pwd,
+				})
+
+				if err != nil {
+					return err
+				}
+
+				return nil
+			case sProto.Body_ANSWER:
+				remoteCred, err := signal.UnMarshalCredential(msg)
+				if err != nil {
+					return err
+				}
+				err = conn.OnAnswer(IceCredentials{
+					uFrag: remoteCred.UFrag,
+					pwd:   remoteCred.Pwd,
+				})
+
+				if err != nil {
+					return err
+				}
+
+			case sProto.Body_CANDIDATE:
+
+				candidate, err := ice.UnmarshalCandidate(msg.GetBody().Payload)
+				if err != nil {
+					log.Errorf("failed on parsing remote candidate %s -> %s", candidate, err)
+					return err
+				}
+
+				err = conn.OnRemoteCandidate(candidate)
+				if err != nil {
+					log.Errorf("error handling CANDIATE from %s", msg.Key)
+					return err
+				}
 			}
 
 			return nil
-		case sProto.Body_ANSWER:
+		})
-			remoteCred, err := signal.UnMarshalCredential(msg)
+		if err != nil {
-			if err != nil {
+			// happens if signal is unavailable for a long time.
-				return err
+			// We want to cancel the operation of the whole client
-			}
+			e.cancel()
-			err = conn.OnAnswer(IceCredentials{
+			return
-				uFrag: remoteCred.UFrag,
-				pwd:   remoteCred.Pwd,
-			})
-
-			if err != nil {
-				return err
-			}
-
-		case sProto.Body_CANDIDATE:
-
-			candidate, err := ice.UnmarshalCandidate(msg.GetBody().Payload)
-			if err != nil {
-				log.Errorf("failed on parsing remote candidate %s -> %s", candidate, err)
-				return err
-			}
-
-			err = conn.OnRemoteCandidate(candidate)
-			if err != nil {
-				log.Errorf("error handling CANDIATE from %s", msg.Key)
-				return err
-			}
 		}
+	}()
 
-		return nil
+	e.signal.WaitStreamConnected()
-	})
-
-	e.signal.WaitConnected()
 }

management/client/client.go

@@ -3,6 +3,7 @@ package client
 import (
 	"context"
 	"crypto/tls"
+	"fmt"
 	"github.com/cenkalti/backoff/v4"
 	log "github.com/sirupsen/logrus"
 	"github.com/wiretrustee/wiretrustee/client/system"
@@ -10,6 +11,7 @@ import (
 	"github.com/wiretrustee/wiretrustee/management/proto"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
 	"io"
@@ -71,12 +73,18 @@ func defaultBackoff(ctx context.Context) backoff.BackOff {
 		RandomizationFactor: backoff.DefaultRandomizationFactor,
 		Multiplier:          backoff.DefaultMultiplier,
 		MaxInterval:         10 * time.Second,
-		MaxElapsedTime:      30 * time.Minute, //stop after an 30 min of trying, the error will be propagated to the general retry of the client
+		MaxElapsedTime:      12 * time.Hour, //stop after 12 hours of trying, the error will be propagated to the general retry of the client
 		Stop:                backoff.Stop,
 		Clock:               backoff.SystemClock,
 	}, ctx)
 }
 
+// ready indicates whether the client is okay and ready to be used
+// for now it just checks whether gRPC connection to the service is ready
+func (c *Client) ready() bool {
+	return c.conn.GetState() == connectivity.Ready
+}
+
 // Sync wraps the real client's Sync endpoint call and takes care of retries and encryption/decryption of messages
 // Blocking request. The result will be sent via msgHandler callback function
 func (c *Client) Sync(msgHandler func(msg *proto.SyncResponse) error) error {
@@ -85,6 +93,12 @@ func (c *Client) Sync(msgHandler func(msg *proto.SyncResponse) error) error {
 
 	operation := func() error {
 
+		log.Debugf("management connection state %v", c.conn.GetState())
+
+		if !c.ready() {
+			return fmt.Errorf("no connection to management")
+		}
+
 		// todo we already have it since we did the Login, maybe cache it locally?
 		serverPubKey, err := c.GetServerPublicKey()
 		if err != nil {
@@ -98,7 +112,7 @@ func (c *Client) Sync(msgHandler func(msg *proto.SyncResponse) error) error {
 			return err
 		}
 
-		log.Infof("connected to the Management Service Stream")
+		log.Infof("connected to the Management Service stream")
 
 		// blocking until error
 		err = c.receiveEvents(stream, *serverPubKey, msgHandler)
@@ -139,7 +153,7 @@ func (c *Client) receiveEvents(stream proto.ManagementService_SyncClient, server
 	for {
 		update, err := stream.Recv()
 		if err == io.EOF {
-			log.Errorf("managment stream was closed: %s", err)
+			log.Errorf("Management stream has been closed by server: %s", err)
 			return err
 		}
 		if err != nil {
@@ -165,6 +179,10 @@ func (c *Client) receiveEvents(stream proto.ManagementService_SyncClient, server
 
 // GetServerPublicKey returns server Wireguard public key (used later for encrypting messages sent to the server)
 func (c *Client) GetServerPublicKey() (*wgtypes.Key, error) {
+	if !c.ready() {
+		return nil, fmt.Errorf("no connection to management")
+	}
+
 	mgmCtx, cancel := context.WithTimeout(c.ctx, 5*time.Second) //todo make a general setting
 	defer cancel()
 	resp, err := c.realClient.GetServerKey(mgmCtx, &proto.Empty{})
@@ -181,6 +199,9 @@ func (c *Client) GetServerPublicKey() (*wgtypes.Key, error) {
 }
 
 func (c *Client) login(serverKey wgtypes.Key, req *proto.LoginRequest) (*proto.LoginResponse, error) {
+	if !c.ready() {
+		return nil, fmt.Errorf("no connection to management")
+	}
 	loginReq, err := encryption.EncryptMessage(serverKey, c.key, req)
 	if err != nil {
 		log.Errorf("failed to encrypt message: %s", err)

signal/client/client.go

@@ -11,6 +11,7 @@ import (
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
@@ -23,6 +24,12 @@ import (
 
 // A set of tools to exchange connection details (Wireguard endpoints) with the remote peer.
 
+// Status is the status of the client
+type Status string
+
+const streamConnected Status = "streamConnected"
+const streamDisconnected Status = "streamDisconnected"
+
 // Client Wraps the Signal Exchange Service gRpc client
 type Client struct {
 	key        wgtypes.Key
@@ -30,8 +37,11 @@ type Client struct {
 	signalConn *grpc.ClientConn
 	ctx        context.Context
 	stream     proto.SignalExchange_ConnectStreamClient
-	//waiting group to notify once stream is connected
+	// connectedCh used to notify goroutines waiting for the connection to the Signal stream
-	connWg *sync.WaitGroup //todo use a channel instead??
+	connectedCh chan struct{}
+	mux         sync.Mutex
+	// streamConnected indicates whether this client is streamConnected to the Signal stream
+	status Status
 }
 
 // Close Closes underlying connections to the Signal Exchange
@@ -65,13 +75,13 @@ func NewClient(ctx context.Context, addr string, key wgtypes.Key, tlsEnabled boo
 		return nil, err
 	}
 
-	var wg sync.WaitGroup
 	return &Client{
 		realClient: proto.NewSignalExchangeClient(conn),
 		ctx:        ctx,
 		signalConn: conn,
 		key:        key,
-		connWg:     &wg,
+		mux:        sync.Mutex{},
+		status:     streamDisconnected,
 	}, nil
 }
 
@@ -82,7 +92,7 @@ func defaultBackoff(ctx context.Context) backoff.BackOff {
 		RandomizationFactor: backoff.DefaultRandomizationFactor,
 		Multiplier:          backoff.DefaultMultiplier,
 		MaxInterval:         10 * time.Second,
-		MaxElapsedTime:      30 * time.Minute, //stop after an 30 min of trying, the error will be propagated to the general retry of the client
+		MaxElapsedTime:      12 * time.Hour, //stop after 12 hours of trying, the error will be propagated to the general retry of the client
 		Stop:                backoff.Stop,
 		Clock:               backoff.SystemClock,
 	}, ctx)
@@ -91,38 +101,76 @@ func defaultBackoff(ctx context.Context) backoff.BackOff {
 
 // Receive Connects to the Signal Exchange message stream and starts receiving messages.
 // The messages will be handled by msgHandler function provided.
-// This function runs a goroutine underneath and reconnects to the Signal Exchange if errors occur (e.g. Exchange restart)
+// This function is blocking and reconnects to the Signal Exchange if errors occur (e.g. Exchange restart)
-// The key is the identifier of our Peer (could be Wireguard public key)
+// The connection retry logic will try to reconnect for 30 min and if wasn't successful will propagate the error to the function caller.
-func (c *Client) Receive(msgHandler func(msg *proto.Message) error) {
+func (c *Client) Receive(msgHandler func(msg *proto.Message) error) error {
-	c.connWg.Add(1)
-	go func() {
 
-		var backOff = defaultBackoff(c.ctx)
+	var backOff = defaultBackoff(c.ctx)
 
-		operation := func() error {
+	operation := func() error {
 
-			stream, err := c.connect(c.key.PublicKey().String())
+		c.notifyStreamDisconnected()
-			if err != nil {
-				log.Warnf("disconnected from the Signal Exchange due to an error: %v", err)
-				c.connWg.Add(1)
-				return err
-			}
 
-			err = c.receive(stream, msgHandler)
+		log.Debugf("signal connection state %v", c.signalConn.GetState())
-			if err != nil {
+		if !c.ready() {
-				backOff.Reset()
+			return fmt.Errorf("no connection to signal")
-				return err
-			}
-
-			return nil
 		}
 
-		err := backoff.Retry(operation, backOff)
+		// connect to Signal stream identifying ourselves with a public Wireguard key
+		// todo once the key rotation logic has been implemented, consider changing to some other identifier (received from management)
+		stream, err := c.connect(c.key.PublicKey().String())
 		if err != nil {
-			log.Errorf("exiting Signal Service connection retry loop due to unrecoverable error: %s", err)
+			log.Warnf("streamDisconnected from the Signal Exchange due to an error: %v", err)
-			return
+			return err
 		}
-	}()
+
+		c.notifyStreamConnected()
+
+		log.Infof("streamConnected to the Signal Service stream")
+
+		// start receiving messages from the Signal stream (from other peers through signal)
+		err = c.receive(stream, msgHandler)
+		if err != nil {
+			log.Warnf("streamDisconnected from the Signal Exchange due to an error: %v", err)
+			backOff.Reset()
+			return err
+		}
+
+		return nil
+	}
+
+	err := backoff.Retry(operation, backOff)
+	if err != nil {
+		log.Errorf("exiting Signal Service connection retry loop due to unrecoverable error: %s", err)
+		return err
+	}
+
+	return nil
+}
+func (c *Client) notifyStreamDisconnected() {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	c.status = streamDisconnected
+}
+
+func (c *Client) notifyStreamConnected() {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	c.status = streamConnected
+	if c.connectedCh != nil {
+		// there are goroutines waiting on this channel -> release them
+		close(c.connectedCh)
+		c.connectedCh = nil
+	}
+}
+
+func (c *Client) getStreamStatusChan() <-chan struct{} {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	if c.connectedCh == nil {
+		c.connectedCh = make(chan struct{})
+	}
+	return c.connectedCh
 }
 
 func (c *Client) connect(key string) (proto.SignalExchange_ConnectStreamClient, error) {
@@ -147,24 +195,37 @@ func (c *Client) connect(key string) (proto.SignalExchange_ConnectStreamClient,
 	if len(registered) == 0 {
 		return nil, fmt.Errorf("didn't receive a registration header from the Signal server whille connecting to the streams")
 	}
-	//connection established we are good to use the stream
-	c.connWg.Done()
-
-	log.Infof("connected to the Signal Exchange Stream")
 
 	return stream, nil
 }
 
-// WaitConnected waits until the client is connected to the message stream
+// ready indicates whether the client is okay and ready to be used
-func (c *Client) WaitConnected() {
+// for now it just checks whether gRPC connection to the service is in state Ready
-	c.connWg.Wait()
+func (c *Client) ready() bool {
+	return c.signalConn.GetState() == connectivity.Ready
+}
+
+// WaitStreamConnected waits until the client is connected to the Signal stream
+func (c *Client) WaitStreamConnected() {
+
+	if c.status == streamConnected {
+		return
+	}
+
+	ch := c.getStreamStatusChan()
+	select {
+	case <-c.ctx.Done():
+	case <-ch:
+	}
 }
 
 // SendToStream sends a message to the remote Peer through the Signal Exchange using established stream connection to the Signal Server
 // The Client.Receive method must be called before sending messages to establish initial connection to the Signal Exchange
 // Client.connWg can be used to wait
 func (c *Client) SendToStream(msg *proto.EncryptedMessage) error {
-
+	if !c.ready() {
+		return fmt.Errorf("no connection to signal")
+	}
 	if c.stream == nil {
 		return fmt.Errorf("connection to the Signal Exchnage has not been established yet. Please call Client.Receive before sending messages")
 	}
@@ -221,13 +282,17 @@ func (c *Client) encryptMessage(msg *proto.Message) (*proto.EncryptedMessage, er
 // Send sends a message to the remote Peer through the Signal Exchange.
 func (c *Client) Send(msg *proto.Message) error {
 
+	if !c.ready() {
+		return fmt.Errorf("no connection to signal")
+	}
+
 	encryptedMessage, err := c.encryptMessage(msg)
 	if err != nil {
 		return err
 	}
 	_, err = c.realClient.Send(context.TODO(), encryptedMessage)
 	if err != nil {
-		log.Errorf("error while sending message to peer [%s] [error: %v]", msg.RemoteKey, err)
+		//log.Errorf("error while sending message to peer [%s] [error: %v]", msg.RemoteKey, err)
 		return err
 	}
 
@@ -244,10 +309,10 @@ func (c *Client) receive(stream proto.SignalExchange_ConnectStreamClient,
 			log.Warnf("stream canceled (usually indicates shutdown)")
 			return err
 		} else if s.Code() == codes.Unavailable {
-			log.Warnf("server has been stopped")
+			log.Warnf("Signal Service is unavailable")
 			return err
 		} else if err == io.EOF {
-			log.Warnf("stream closed by server")
+			log.Warnf("Signal Service stream closed by server")
 			return err
 		} else if err != nil {
 			return err

signal/client/client_test.go

@@ -36,7 +36,7 @@ var _ = Describe("Client", func() {
 	})
 
 	Describe("Exchanging messages", func() {
-		Context("between connected peers", func() {
+		Context("between streamConnected peers", func() {
 			It("should be successful", func() {
 
 				var msgReceived sync.WaitGroup
@@ -48,30 +48,42 @@ var _ = Describe("Client", func() {
 				// connect PeerA to Signal
 				keyA, _ := wgtypes.GenerateKey()
 				clientA := createSignalClient(addr, keyA)
-				clientA.Receive(func(msg *sigProto.Message) error {
+				go func() {
-					receivedOnA = msg.GetBody().GetPayload()
+					err := clientA.Receive(func(msg *sigProto.Message) error {
-					msgReceived.Done()
+						receivedOnA = msg.GetBody().GetPayload()
-					return nil
+						msgReceived.Done()
-				})
+						return nil
-				clientA.WaitConnected()
+					})
+					if err != nil {
+						return
+					}
+				}()
+				clientA.WaitStreamConnected()
 
 				// connect PeerB to Signal
 				keyB, _ := wgtypes.GenerateKey()
 				clientB := createSignalClient(addr, keyB)
-				clientB.Receive(func(msg *sigProto.Message) error {
+
-					receivedOnB = msg.GetBody().GetPayload()
+				go func() {
-					err := clientB.Send(&sigProto.Message{
+					err := clientB.Receive(func(msg *sigProto.Message) error {
-						Key:       keyB.PublicKey().String(),
+						receivedOnB = msg.GetBody().GetPayload()
-						RemoteKey: keyA.PublicKey().String(),
+						err := clientB.Send(&sigProto.Message{
-						Body:      &sigProto.Body{Payload: "pong"},
+							Key:       keyB.PublicKey().String(),
+							RemoteKey: keyA.PublicKey().String(),
+							Body:      &sigProto.Body{Payload: "pong"},
+						})
+						if err != nil {
+							Fail("failed sending a message to PeerA")
+						}
+						msgReceived.Done()
+						return nil
 					})
 					if err != nil {
-						Fail("failed sending a message to PeerA")
+						return
 					}
-					msgReceived.Done()
+				}()
-					return nil
+
-				})
+				clientB.WaitStreamConnected()
-				clientB.WaitConnected()
 
 				// PeerA initiates ping-pong
 				err := clientA.Send(&sigProto.Message{
@@ -100,11 +112,15 @@ var _ = Describe("Client", func() {
 
 				key, _ := wgtypes.GenerateKey()
 				client := createSignalClient(addr, key)
-				client.Receive(func(msg *sigProto.Message) error {
+				go func() {
-					return nil
+					err := client.Receive(func(msg *sigProto.Message) error {
-				})
+						return nil
-				client.WaitConnected()
+					})
-
+					if err != nil {
+						return
+					}
+				}()
+				client.WaitStreamConnected()
 				Expect(client).NotTo(BeNil())
 			})
 		})