Update

vendor/tailscale.com/net/routecheck/peernode/reachability.go

@@ -0,0 +1,39 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+package peernode
+
+import "fmt"
+
+// Reachability reports whether a peer node is reachable.
+type Reachability int
+
+const (
+	// Unknown is a peer node whose reachability is unknown.
+	// This peer is new and we have yet to probe it.
+	Unknown Reachability = iota
+	// Reachable is a peer node that is reachable from this node.
+	Reachable
+	// Unreachable is a peer node that is unreachable from this node.
+	// This peer is not responding to probes.
+	Unreachable
+)
+
+// String implements [fmt.Stringer].
+func (r Reachability) String() string {
+	switch r {
+	case Unknown:
+		return "Unknown"
+	case Reachable:
+		return "Reachable"
+	case Unreachable:
+		return "Unreachable"
+	default:
+		panic(fmt.Sprintf("unknown %#v", r))
+	}
+}
+
+// IsReachable reports if r is [Reachable].
+func (r Reachability) IsReachable() bool {
+	return r == Reachable
+}