peer: call disableChannel with disabled=false after loading channels

This to ensure now active channel is available in the router, for path
finding, as it might have been disabled if the peer has been offline a
while.

peer.go

@@ -318,6 +318,7 @@ func (p *peer) Start() error {
 // loadActiveChannels creates indexes within the peer for tracking all active
 // channels returned by the database.
 func (p *peer) loadActiveChannels(chans []*channeldb.OpenChannel) error {
+	var activeChans []wire.OutPoint
 	for _, dbChan := range chans {
 		lnChan, err := lnwallet.NewLightningChannel(
 			p.server.cc.signer, p.server.witnessBeacon, dbChan,
@@ -425,8 +426,26 @@ func (p *peer) loadActiveChannels(chans []*channeldb.OpenChannel) error {
 		p.activeChanMtx.Lock()
 		p.activeChannels[chanID] = lnChan
 		p.activeChanMtx.Unlock()
+
+		activeChans = append(activeChans, *chanPoint)
 	}
 
+	// As a final measure we launch a goroutine that will ensure the
+	// channels are not currently disabled, as that will make us skip it
+	// during path finding.
+	go func() {
+		for _, chanPoint := range activeChans {
+			// Set the channel disabled=false by sending out a new
+			// ChannelUpdate. If this channel is already active,
+			// the update won't be sent.
+			err := p.server.announceChanStatus(chanPoint, false)
+			if err != nil {
+				peerLog.Errorf("unable to send out active "+
+					"channel update: %v", err)
+			}
+		}
+	}()
+
 	return nil
 }
 

server.go

@@ -3112,6 +3112,9 @@ func (s *server) watchChannelStatus() {
 
 			// We'll send out an update for all channels that have
 			// had their status unchanged for longer than the limit.
+			// NOTE: We also make sure to activate any channel when
+			// we connect to a peer, to make them available for
+			// path finding immediately.
 			for op, st := range status {
 				disable := !st.active