lnd: add new "perm" bit to the ConnectPeer RPC call

This commit modifies the ConnectPeer RPC call and partitions the
behavior of the call into two scenarios: the connection should be
persistent which causes the call to be non-blocking, and the connection
should only attempt to connect once — which causes the call to be
blocking and report any error back to the caller.

As a result, the pendingConnRequest map and the logic around it is no
longer needed.

peer.go

@@ -263,6 +263,8 @@ func (p *peer) Start() error {
 		return nil
 	}
 
+	atomic.AddInt32(&p.connected, 1)
+
 	peerLog.Tracef("peer %v starting", p)
 
 	p.wg.Add(5)

rpcserver.go

@@ -215,15 +215,13 @@ func (r *rpcServer) ConnectPeer(ctx context.Context,
 		ChainNet:    activeNetParams.Net,
 	}
 
-	peerID, err := r.server.ConnectToPeer(peerAddr)
-	if err != nil {
+	if err := r.server.ConnectToPeer(peerAddr, in.Perm); err != nil {
 		rpcsLog.Errorf("(connectpeer): error connecting to peer: %v", err)
 		return nil, err
 	}
 
-	// TODO(roasbeef): add pubkey return
 	rpcsLog.Debugf("Connected to peer: %v", peerAddr.String())
-	return &lnrpc.ConnectPeerResponse{peerID}, nil
+	return &lnrpc.ConnectPeerResponse{}, nil
 }
 
 // OpenChannel attempts to open a singly funded channel specified in the

server.go

@@ -66,9 +66,8 @@ type server struct {
 
 	connMgr *connmgr.ConnManager
 
-	pendingConnMtx      sync.RWMutex
-	persistentConnReqs  map[string]*connmgr.ConnReq
-	pendingConnRequests map[string]*connectPeerMsg
+	pendingConnMtx     sync.RWMutex
+	persistentConnReqs map[string]*connmgr.ConnReq
 
 	broadcastRequests chan *broadcastReq
 	sendRequests      chan *sendReq
@@ -118,8 +117,7 @@ func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 		sphinx:      sphinx.NewRouter(privKey, activeNetParams.Params),
 		lightningID: fastsha256.Sum256(serializedPubKey),
 
-		pendingConnRequests: make(map[string]*connectPeerMsg),
-		persistentConnReqs:  make(map[string]*connmgr.ConnReq),
+		persistentConnReqs: make(map[string]*connmgr.ConnReq),
 
 		peersByID:  make(map[int32]*peer),
 		peersByPub: make(map[string]*peer),
@@ -224,11 +222,6 @@ func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
 		}
 		s.persistentConnReqs[pubStr] = connReq
 		go s.connMgr.Connect(connReq)
-
-		s.pendingConnRequests[pubStr] = &connectPeerMsg{
-			resp: make(chan int32, 1),
-			err:  make(chan error, 1),
-		}
 	}
 
 	return s, nil
@@ -411,22 +404,6 @@ func (s *server) peerConnected(conn net.Conn, connReq *connmgr.ConnReq, inbound
 
 	peer.Start()
 	s.newPeers <- peer
-
-	// If this was an RPC initiated outbound connection that was
-	// successfully established, then send a response back to the client so
-	// they won't be blocked indefinitely.
-	pubStr := string(peerAddr.IdentityKey.SerializeCompressed())
-	s.pendingConnMtx.RLock()
-	msg, ok := s.pendingConnRequests[pubStr]
-	s.pendingConnMtx.RUnlock()
-	if ok {
-		msg.resp <- peer.id
-		msg.err <- nil
-
-		s.pendingConnMtx.Lock()
-		delete(s.pendingConnRequests, pubStr)
-		s.pendingConnMtx.Unlock()
-	}
 }
 
 // inboundPeerConnected initializes a new peer in response to a new inbound
@@ -541,9 +518,10 @@ func (s *server) removePeer(p *peer) {
 // particular peer. This message also houses an error channel which will be
 // used to report success/failure.
 type connectPeerMsg struct {
-	addr *lnwire.NetAddress
-	resp chan int32
-	err  chan error
+	addr       *lnwire.NetAddress
+	persistent bool
+
+	err chan error
 }
 
 // listPeersMsg is a message sent to the server in order to obtain a listing
@@ -686,7 +664,6 @@ func (s *server) handleConnectPeer(msg *connectPeerMsg) {
 	if ok {
 		s.peersMtx.RUnlock()
 		msg.err <- fmt.Errorf("already connected to peer: %v", peer)
-		msg.resp <- -1
 		return
 	}
 	s.peersMtx.RUnlock()
@@ -695,18 +672,10 @@ func (s *server) handleConnectPeer(msg *connectPeerMsg) {
 	// then we ignore this request to ensure we don't create a redundant
 	// connection.
 	s.pendingConnMtx.RLock()
-	if _, ok := s.pendingConnRequests[targetPub]; ok {
-		s.pendingConnMtx.RUnlock()
-		msg.err <- fmt.Errorf("connection attempt to %v is pending",
-			addr)
-		msg.resp <- -1
-		return
-	}
 	if _, ok := s.persistentConnReqs[targetPub]; ok {
 		s.pendingConnMtx.RUnlock()
 		msg.err <- fmt.Errorf("connection attempt to %v is pending",
 			addr)
-		msg.resp <- -1
 		return
 	}
 	s.pendingConnMtx.RUnlock()
@@ -715,20 +684,29 @@ func (s *server) handleConnectPeer(msg *connectPeerMsg) {
 	// then instruct the connection manager to attempt to establish a
 	// persistent connection to the peer.
 	srvrLog.Debugf("Connecting to %v", addr)
-	go s.connMgr.Connect(&connmgr.ConnReq{
-		Addr:      addr,
-		Permanent: true,
-	})
+	if msg.persistent {
+		go s.connMgr.Connect(&connmgr.ConnReq{
+			Addr:      addr,
+			Permanent: true,
+		})
+	} else {
+		// If we're not making a persistent connection, then we'll
+		// attempt to connect o the target peer, returning an error
+		// which indicates success of failure.
+		go func() {
+			// Attempt to connect to the remote node. If the we
+			// can't make the connection, or the crypto negotiation
+			// breaks down, then return an error to the caller.
+			conn, err := brontide.Dial(s.identityPriv, addr)
+			if err != nil {
+				msg.err <- err
+				return
+			}
 
-	// TODO(roasbeef): create goroutine to poll state so can report
-	// connection fails
-
-	// Finally, we store the original request keyed by the public key so we
-	// can dispatch the response to the RPC client once a connection has
-	// been initiated.
-	s.pendingConnMtx.Lock()
-	s.pendingConnRequests[targetPub] = msg
-	s.pendingConnMtx.Unlock()
+			s.outboundPeerConnected(nil, conn)
+			msg.err <- nil
+		}()
+	}
 }
 
 // handleOpenChanReq first locates the target peer, and if found hands off the
@@ -767,13 +745,18 @@ func (s *server) handleOpenChanReq(req *openChanReq) {
 // ConnectToPeer requests that the server connect to a Lightning Network peer
 // at the specified address. This function will *block* until either a
 // connection is established, or the initial handshake process fails.
-func (s *server) ConnectToPeer(addr *lnwire.NetAddress) (int32, error) {
-	reply := make(chan int32, 1)
+func (s *server) ConnectToPeer(addr *lnwire.NetAddress,
+	perm bool) error {
+
 	errChan := make(chan error, 1)
 
-	s.queries <- &connectPeerMsg{addr, reply, errChan}
+	s.queries <- &connectPeerMsg{
+		addr:       addr,
+		persistent: perm,
+		err:        errChan,
+	}
 
-	return <-reply, <-errChan
+	return <-errChan
 }
 
 // OpenChannel sends a request to the server to open a channel to the specified