Update

vendor/tailscale.com/net/routecheck/report.go

@@ -0,0 +1,166 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+package routecheck
+
+import (
+	"cmp"
+	"iter"
+	"maps"
+	"net/netip"
+	"slices"
+	"time"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
+	jsonv1 "github.com/go-json-experiment/json/v1"
+
+	"tailscale.com/net/routecheck/peernode"
+	"tailscale.com/tailcfg"
+	"tailscale.com/util/clientmetric"
+	"tailscale.com/util/mak"
+)
+
+var (
+	metricReport = clientmetric.NewCounter("routecheck_report")
+)
+
+// Report returns the latest reachability report.
+// It returns nil if a report isn’t available, which happens during initialization.
+func (c *Client) Report() *Report {
+	metricReport.Add(1)
+	return c.report.Load()
+}
+
+// Report contains the result of a single routecheck.
+type Report struct {
+	// Done is the time when the report was finished.
+	Done time.Time `json:"done"`
+
+	// Reachable is the set of nodes that were reachable from the current host
+	// when this report was compiled. Missing nodes may or may not be reachable.
+	Reachable NodeSet `json:"reachable"`
+
+	// LastProbed tracks the last time a given node was probed.
+	// This is used to rate-limit reachability probing, so an entry’s
+	// presence doesn’t imply that it is reachable.
+	LastProbed map[tailcfg.NodeID]time.Time `json:"-"` // not marshaled
+}
+
+// IsReachable reports whether a peer is reachable by the current node.
+func (rp Report) IsReachable(id tailcfg.NodeID) peernode.Reachability {
+	// TODO(sfllaw): We should actually track all routers and consider the
+	// absence of a router in the report as it being recently added for
+	// consideration, so it is unknown. Then we should positively track
+	// whether a node was reachable or not.
+	_, k := rp.Reachable[id]
+	if k {
+		return peernode.Reachable
+	}
+	return peernode.Unknown
+}
+
+// RoutablePrefixes returns a map of routable network prefixes associated with
+// each prefix’s routers that were reachable by the current host,
+// at the time the report was finished.
+// Each slice of routers are ordered by their node ID.
+//
+// Note: Fallback routes are not supported by design. If a subnet prefix
+// contained within another more general prefix has no reachable routers,
+// traffic is still sent to one of those unreachable routers.
+// Routers for the general prefix aren’t candidates. See tailscale/tailscale#18550.
+func (rp Report) RoutablePrefixes() RoutablePrefixes {
+	var out map[netip.Prefix][]Node
+	for _, n := range rp.Reachable {
+		for _, p := range n.Routes {
+			mak.Set(&out, p, append(out[p], n))
+		}
+	}
+	for p := range out {
+		slices.SortFunc(out[p], Node.Compare)
+	}
+	return out
+}
+
+// Node represents a node in the reachability report.
+type Node struct {
+	ID tailcfg.NodeID `json:"id"`
+
+	// Name is the FQDN of the node.
+	// It is also the MagicDNS name for the node.
+	// It has a trailing dot.
+	// e.g. "host.tail-scale.ts.net."
+	Name string `json:"name"`
+
+	// Addr is the IP address that was probed.
+	Addr netip.Addr `json:"addr"`
+
+	// Routes are the subnets that the node will route.
+	Routes []netip.Prefix `json:"routes"`
+}
+
+// Compare returns an integer comparing two nodes, ordered by their node ID.
+// The result will be 0 if n.ID == n2.ID, -1 if n.ID < n2.ID, and +1 if n.ID > n2.ID.
+func (n Node) Compare(n2 Node) int {
+	return cmp.Compare(n.ID, n2.ID)
+}
+
+// NodeSet is a set of nodes keyed by node ID, so duplicates are easily detected.
+// To prevent stuttering, it marshals itself as a JSON array, sorted by node ID.
+type NodeSet map[tailcfg.NodeID]Node
+
+var (
+	_ jsonv1.Marshaler       = &NodeSet{}
+	_ jsonv1.Unmarshaler     = &NodeSet{}
+	_ jsonv2.MarshalerTo     = &NodeSet{}
+	_ jsonv2.UnmarshalerFrom = &NodeSet{}
+)
+
+// MarshalJSONTo implements [jsonv2.MarshalerTo].
+func (ns NodeSet) MarshalJSONTo(enc *jsontext.Encoder) error {
+	nodes := slices.SortedFunc(maps.Values(ns), Node.Compare)
+	return jsonv2.MarshalEncode(enc, nodes)
+}
+
+// UnmarshalJSONFrom implements [jsonv2.UnmarshalerFrom].
+func (ns *NodeSet) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
+	var nodes []Node
+	if err := jsonv2.UnmarshalDecode(dec, &nodes); err != nil {
+		return err
+	}
+	if *ns == nil {
+		*ns = make(NodeSet, len(nodes))
+	}
+	for _, n := range nodes {
+		(*ns)[n.ID] = n
+	}
+	return nil
+}
+
+// MarshalJSON implements [jsonv1.Marshaler].
+func (ns *NodeSet) MarshalJSON() ([]byte, error) {
+	return jsonv2.Marshal(ns, jsonv1.DefaultOptionsV1())
+}
+
+// UnmarshalJSON implements [jsonv1.Unmarshaler].
+func (ns *NodeSet) UnmarshalJSON(b []byte) error {
+	return jsonv2.Unmarshal(b, ns, jsonv1.DefaultOptionsV1())
+
+}
+
+// RoutablePrefixes is a map of routers,
+// keyed by the network prefix for which they route.
+type RoutablePrefixes map[netip.Prefix][]Node
+
+// Sorted returns an iterator over the map of routers,
+// ordered by the network prefix as described in [netip.Prefix.Compare].
+func (rt RoutablePrefixes) Sorted() iter.Seq2[netip.Prefix, []Node] {
+	return func(yield func(netip.Prefix, []Node) bool) {
+		prefixes := slices.SortedFunc(maps.Keys(rt), netip.Prefix.Compare)
+		for _, p := range prefixes {
+			if !yield(p, rt[p]) {
+				return
+			}
+		}
+	}
+}