ipn: add KeyExpiry to PeerStatus

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I9466ff3d3d92b64255b694394a4b5b508da074a5

ipn/ipnlocal/local.go

@@ -720,6 +720,7 @@ func peerStatusFromNode(ps *ipnstate.PeerStatus, n *tailcfg.Node) {
 		ps.PrimaryRoutes = &v
 	}
 
+	ps.KeyExpiry = n.KeyExpiry
 	if n.Expired {
 		ps.Expired = true
 	}

ipn/ipnstate/ipnstate.go

@@ -247,6 +247,10 @@ type PeerStatus struct {
 	// In theory, all of InNetworkMap and InMagicSock and InEngine should all be true.
 	InEngine bool
 
+	// KeyExpiry is the time that this peer's node key will or has expired.
+	// This will be the zero time for nodes that do not expire.
+	KeyExpiry time.Time `json:",omitempty"`
+
 	// Expired means that this peer's node key has expired, based on either
 	// information from control or optimisically set on the client if the
 	// expiration time has passed.