ipn/ipnlocal: always set Notify.FilesWaiting, set IncomingFiles non-nil when empty

ipn/backend.go

@@ -67,8 +67,17 @@ type Notify struct {
 	BackendLogID  *string            // public logtail id used by backend
 	PingResult    *ipnstate.PingResult
 
-	FilesWaiting  *empty.Message `json:",omitempty"`
-	IncomingFiles []PartialFile  `json:",omitempty"`
+	// FilesWaiting if non-nil means that files are buffered in
+	// the Tailscale daemon and ready for local transfer to the
+	// user's preferred storage location.
+	FilesWaiting *empty.Message `json:",omitempty"`
+
+	// IncomingFiles, if non-nil, specifies which files are in the
+	// process of being received. A nil IncomingFiles means this
+	// Notify should not update the state of file transfers. A non-nil
+	// but empty IncomingFiles means that no files are in the middle
+	// of being transferred.
+	IncomingFiles []PartialFile `json:",omitempty"`
 
 	// LocalTCPPort, if non-nil, informs the UI frontend which
 	// (non-zero) localhost TCP port it's listening on.

ipn/ipnlocal/local.go

@@ -927,6 +927,7 @@ func (b *LocalBackend) readPoller() {
 func (b *LocalBackend) send(n ipn.Notify) {
 	b.mu.Lock()
 	notifyFunc := b.notify
+	apiSrv := b.peerAPIServer
 	b.mu.Unlock()
 
 	if notifyFunc == nil {
@@ -934,6 +935,10 @@ func (b *LocalBackend) send(n ipn.Notify) {
 		return
 	}
 
+	if apiSrv != nil && apiSrv.hasFilesWaiting() {
+		n.FilesWaiting = &empty.Message{}
+	}
+
 	n.Version = version.Long
 	notifyFunc(n)
 }
@@ -949,9 +954,10 @@ func (b *LocalBackend) sendFileNotify() {
 		return
 	}
 
-	if apiSrv.hasFilesWaiting() {
-		n.FilesWaiting = &empty.Message{}
-	}
+	// Make sure we always set n.IncomingFiles non-nil so it gets encoded
+	// in JSON to clients. They distinguish between empty and non-nil
+	// to know whether a Notify should be able about files.
+	n.IncomingFiles = make([]ipn.PartialFile, 0)
 	for f := range b.incomingFiles {
 		n.IncomingFiles = append(n.IncomingFiles, f.PartialFile())
 	}