cmd/tailscale, wgengine, tailcfg: don't assume LastSeen is present [mapver 20]

Updates #2107

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/file.go

@@ -97,14 +97,12 @@ func runCp(ctx context.Context, args []string) error {
 		return err
 	}
 
-	peerAPIBase, lastSeen, isOffline, err := discoverPeerAPIBase(ctx, ip)
+	peerAPIBase, isOffline, err := discoverPeerAPIBase(ctx, ip)
 	if err != nil {
 		return fmt.Errorf("can't send to %s: %v", target, err)
 	}
 	if isOffline {
 		fmt.Fprintf(os.Stderr, "# warning: %s is offline\n", target)
-	} else if !lastSeen.IsZero() && time.Since(lastSeen) > lastSeenOld {
-		fmt.Fprintf(os.Stderr, "# warning: %s last seen %v ago\n", target, time.Since(lastSeen).Round(time.Minute))
 	}
 
 	if len(files) > 1 {
@@ -182,14 +180,14 @@ func runCp(ctx context.Context, args []string) error {
 	return nil
 }
 
-func discoverPeerAPIBase(ctx context.Context, ipStr string) (base string, lastSeen time.Time, isOffline bool, err error) {
+func discoverPeerAPIBase(ctx context.Context, ipStr string) (base string, isOffline bool, err error) {
 	ip, err := netaddr.ParseIP(ipStr)
 	if err != nil {
-		return "", time.Time{}, false, err
+		return "", false, err
 	}
 	fts, err := tailscale.FileTargets(ctx)
 	if err != nil {
-		return "", time.Time{}, false, err
+		return "", false, err
 	}
 	for _, ft := range fts {
 		n := ft.Node
@@ -197,14 +195,11 @@ func discoverPeerAPIBase(ctx context.Context, ipStr string) (base string, lastSe
 			if a.IP() != ip {
 				continue
 			}
-			if n.LastSeen != nil {
-				lastSeen = *n.LastSeen
-			}
 			isOffline = n.Online != nil && !*n.Online
-			return ft.PeerAPIURL, lastSeen, isOffline, nil
+			return ft.PeerAPIURL, isOffline, nil
 		}
 	}
-	return "", time.Time{}, false, fileTargetErrorDetail(ctx, ip)
+	return "", false, fileTargetErrorDetail(ctx, ip)
 }
 
 // fileTargetErrorDetail returns a non-nil error saying why ip is an
@@ -274,8 +269,6 @@ func (r *slowReader) Read(p []byte) (n int, err error) {
 	return
 }
 
-const lastSeenOld = 20 * time.Minute
-
 func runCpTargets(ctx context.Context, args []string) error {
 	if len(args) > 0 {
 		return errors.New("invalid arguments with --targets")

tailcfg/tailcfg.go

@@ -42,7 +42,8 @@ import (
 //    17: 2021-04-18: MapResponse.Domain empty means unchanged
 //    18: 2021-04-19: MapResponse.Node nil means unchanged (all fields now omitempty)
 //    19: 2021-04-21: MapResponse.Debug.SleepSeconds
-const CurrentMapRequestVersion = 19
+//    20: 2021-06-11: MapResponse.LastSeen used even less (https://github.com/tailscale/tailscale/issues/2107)
+const CurrentMapRequestVersion = 20
 
 type StableID string
 

wgengine/pendopen.go

@@ -5,6 +5,7 @@
 package wgengine
 
 import (
+	"fmt"
 	"os"
 	"runtime"
 	"strconv"
@@ -173,10 +174,6 @@ func (e *userspaceEngine) onOpenTimeout(flow flowtrack.Tuple) {
 		e.logf("open-conn-track: timeout opening %v; peer node %v not connected to any DERP relay", flow, n.Key.ShortString())
 		return
 	}
-	var lastSeen time.Time
-	if n.LastSeen != nil {
-		lastSeen = *n.LastSeen
-	}
 
 	var ps *ipnstate.PeerStatusLite
 	if st, err := e.getStatus(); err == nil {
@@ -228,9 +225,11 @@ func (e *userspaceEngine) onOpenTimeout(flow flowtrack.Tuple) {
 			online = "no"
 		}
 	}
-	e.logf("open-conn-track: timeout opening %v to node %v; lastSeen=%v, online=%v, lastRecv=%v",
+	if n.LastSeen != nil && online != "yes" {
+		online += fmt.Sprintf(", lastseen=%v", durFmt(*n.LastSeen))
+	}
+	e.logf("open-conn-track: timeout opening %v to node %v; online=%v, lastRecv=%v",
 		flow, n.Key.ShortString(),
-		durFmt(lastSeen),
 		online,
 		durFmt(e.magicConn.LastRecvActivityOfDisco(n.DiscoKey)))
 }