[relay] Refactor initial Relay connection (#2800)

Can support firewalls with restricted WS rules

allow to run engine without Relay servers
keep up to date Relay address changes

client/internal/connect.go

@@ -232,6 +232,7 @@ func (c *ConnectClient) run(mobileDependency MobileDependency, probes *ProbeHold
 
 		relayURLs, token := parseRelayInfo(loginResp)
 		relayManager := relayClient.NewManager(engineCtx, relayURLs, myPrivateKey.PublicKey().String())
+		c.statusRecorder.SetRelayMgr(relayManager)
 		if len(relayURLs) > 0 {
 			if token != nil {
 				if err := relayManager.UpdateToken(token); err != nil {
@@ -242,9 +243,7 @@ func (c *ConnectClient) run(mobileDependency MobileDependency, probes *ProbeHold
 			log.Infof("connecting to the Relay service(s): %s", strings.Join(relayURLs, ", "))
 			if err = relayManager.Serve(); err != nil {
 				log.Error(err)
-				return wrapErr(err)
 			}
-			c.statusRecorder.SetRelayMgr(relayManager)
 		}
 
 		peerConfig := loginResp.GetPeerConfig()

client/internal/engine.go

@@ -538,6 +538,7 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 
 		relayMsg := wCfg.GetRelay()
 		if relayMsg != nil {
+			// when we receive token we expect valid address list too
 			c := &auth.Token{
 				Payload:   relayMsg.GetTokenPayload(),
 				Signature: relayMsg.GetTokenSignature(),
@@ -546,9 +547,16 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 				log.Errorf("failed to update relay token: %v", err)
 				return fmt.Errorf("update relay token: %w", err)
 			}
+
+			e.relayManager.UpdateServerURLs(relayMsg.Urls)
+
+			// Just in case the agent started with an MGM server where the relay was disabled but was later enabled.
+			// We can ignore all errors because the guard will manage the reconnection retries.
+			_ = e.relayManager.Serve()
+		} else {
+			e.relayManager.UpdateServerURLs(nil)
 		}
 
-		// todo update relay address in the relay manager
 		// todo update signal
 	}
 

client/internal/peer/status.go

@@ -676,25 +676,23 @@ func (d *Status) GetRelayStates() []relay.ProbeResult {
 	// extend the list of stun, turn servers with relay address
 	relayStates := slices.Clone(d.relayStates)
 
-	var relayState relay.ProbeResult
-
 	// if the server connection is not established then we will use the general address
 	// in case of connection we will use the instance specific address
 	instanceAddr, err := d.relayMgr.RelayInstanceAddress()
 	if err != nil {
 		// TODO add their status
-		if errors.Is(err, relayClient.ErrRelayClientNotConnected) {
-			for _, r := range d.relayMgr.ServerURLs() {
-				relayStates = append(relayStates, relay.ProbeResult{
-					URI: r,
-				})
-			}
-			return relayStates
+		for _, r := range d.relayMgr.ServerURLs() {
+			relayStates = append(relayStates, relay.ProbeResult{
+				URI: r,
+				Err: err,
+			})
 		}
-		relayState.Err = err
+		return relayStates
 	}
 
-	relayState.URI = instanceAddr
+	relayState := relay.ProbeResult{
+		URI: instanceAddr,
+	}
 	return append(relayStates, relayState)
 }
 

client/internal/peer/worker_ice.go

@@ -46,8 +46,6 @@ type WorkerICE struct {
 	hasRelayOnLocally bool
 	conn              WorkerICECallbacks
 
-	selectedPriority ConnPriority
-
 	agent    *ice.Agent
 	muxAgent sync.Mutex
 
@@ -95,10 +93,8 @@ func (w *WorkerICE) OnNewOffer(remoteOfferAnswer *OfferAnswer) {
 
 	var preferredCandidateTypes []ice.CandidateType
 	if w.hasRelayOnLocally && remoteOfferAnswer.RelaySrvAddress != "" {
-		w.selectedPriority = connPriorityICEP2P
 		preferredCandidateTypes = icemaker.CandidateTypesP2P()
 	} else {
-		w.selectedPriority = connPriorityICETurn
 		preferredCandidateTypes = icemaker.CandidateTypes()
 	}
 
@@ -159,7 +155,7 @@ func (w *WorkerICE) OnNewOffer(remoteOfferAnswer *OfferAnswer) {
 		RelayedOnLocal:             isRelayCandidate(pair.Local),
 	}
 	w.log.Debugf("on ICE conn read to use ready")
-	go w.conn.OnConnReady(w.selectedPriority, ci)
+	go w.conn.OnConnReady(selectedPriority(pair), ci)
 }
 
 // OnRemoteCandidate Handles ICE connection Candidate provided by the remote peer.
@@ -394,3 +390,11 @@ func isRelayed(pair *ice.CandidatePair) bool {
 	}
 	return false
 }
+
+func selectedPriority(pair *ice.CandidatePair) ConnPriority {
+	if isRelayed(pair) {
+		return connPriorityICETurn
+	} else {
+		return connPriorityICEP2P
+	}
+}