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d42da2fbd7ff7d2ba10fcbada30e6a1a0aaa2ddb
tailscale/net/routecheck/routecheck_test.go
T
Simon Law cb7e536804 feature/routecheck,ipn/routecheck: probe reachability in the background 
Previously, refreshing the routecheck.Client would probe to generate a
new routecheck.Report, but this method was only wired up to the
LocalAPI and the `tailscale routecheck` command. However, waiting for
a probe to finish before choosing a router would take too long, so we
must keep a regularly updated report to be consulted as necessary.

This patch adds a Start and Close method to the routecheck.Client and
starts it in the background from features/routecheck. To enable this
feature for a given node, set both of the following node attributes:
`client-side-reachability` and `client-side-reachability-routecheck`.

This patch also wires up the RouterTracker.OnRoutersChange hook, which
fires a callback whenever a new network map includes information about
a router node, This signals to the routecheck.Client that it might
need to schedule another probe, if the shape of the routing table has
changed materially.

Updates #17366
Updates tailscale/corp#33033

Signed-off-by: Simon Law <sfllaw@tailscale.com>
2026-07-02 20:26:27 -07:00

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// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause
package routecheck_test
import (
"context"
"fmt"
"maps"
"net/netip"
"slices"
"sync/atomic"
"testing"
"testing/synctest"
"time"
gcmp "github.com/google/go-cmp/cmp"
gcmpopts "github.com/google/go-cmp/cmp/cmpopts"
"tailscale.com/ipn/ipnstate"
"tailscale.com/net/routecheck"
"tailscale.com/net/tsaddr"
"tailscale.com/tailcfg"
"tailscale.com/types/netmap"
"tailscale.com/util/mak"
"tailscale.com/util/set"
)
func TestRefresh(t *testing.T) {
for _, tt := range []struct {
name string
init bool // true before the netmap has been loaded
peers []tailcfg.NodeView
gone []tailcfg.NodeID // cannot ping these nodes
want []tailcfg.NodeID // Report.Reachable nodes
}{
{
name: "wait-for-netmap",
init: true,
peers: []tailcfg.NodeView{
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
},
want: []tailcfg.NodeID{11, 12},
},
{
name: "no-peers",
peers: []tailcfg.NodeView{},
want: []tailcfg.NodeID{},
},
{
name: "no-routers",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
},
want: []tailcfg.NodeID{},
},
{
name: "no-choice",
peers: []tailcfg.NodeView{
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
},
want: []tailcfg.NodeID{},
},
{
name: "all-good",
peers: []tailcfg.NodeView{
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
},
want: []tailcfg.NodeID{11, 12, 21, 22},
},
{
name: "none-good",
peers: []tailcfg.NodeView{
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
},
gone: []tailcfg.NodeID{11, 12, 21, 22},
want: []tailcfg.NodeID{},
},
{
name: "some-good",
peers: []tailcfg.NodeView{
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
},
gone: []tailcfg.NodeID{11, 22},
want: []tailcfg.NodeID{12, 21},
},
} {
makeDB := func(nodes []tailcfg.NodeView) map[tailcfg.NodeID]routecheck.Node {
if len(nodes) == 0 {
return nil
}
db := make(map[tailcfg.NodeID]routecheck.Node)
for _, n := range nodes {
db[n.ID()] = routecheck.Node{
ID: n.ID(),
Name: n.Name(),
Addr: n.Addresses().At(0).Addr(),
Routes: n.AllowedIPs().AsSlice()[2:],
}
}
return db
}
cmpDiff := func(want, got any) string {
return gcmp.Diff(want, got,
gcmpopts.EquateComparable(netip.Addr{}, netip.Prefix{}))
}
t.Run(tt.name, func(t *testing.T) {
synctest.Test(t, func(t *testing.T) {
self := makeNode(99, withName("self"))
var b *stubBackend
if !tt.init {
b = newStubBackend(self, tt.peers,
withGone(t, tt.gone...))
} else {
// The backend is initialized without a NetMap,
// which gets “retrieved” after a delay.
b = newStubBackend(self, tt.peers,
withGone(t, tt.gone...),
withDelay(t, 10*time.Second))
}
t.Cleanup(func() { b.Close() })
c, err := routecheck.NewClient(t.Context(), t.Logf, b, b, b)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if tt.init {
// This callback simulates the delay between
// connecting to the backend and receiving the NetMap.
donef := func() { c.NotifyNetMapAvailable() }
b.donef.Store(&donef)
}
before := time.Now()
got, err := c.Refresh(t.Context(), routecheck.DefaultTimeout)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
after := time.Now() // synctest will freeze time.
peers := makeDB(tt.peers)
want := &routecheck.Report{
Done: after,
}
for _, nid := range tt.want {
mak.Set(&want.Reachable, nid, peers[nid])
}
for _, nodes := range c.RoutersByPrefix() {
if len(nodes) <= 1 {
continue // no choice
}
for _, n := range nodes {
ts := before
if tt.init {
ts = after // waiting for netmap
}
if slices.Contains(tt.gone, n.ID()) {
ts = after // ping timed out
}
mak.Set(&want.LastProbed, n.ID(), ts)
}
}
if diff := cmpDiff(want, got); diff != "" {
t.Errorf("-want +got:\n%s", diff)
}
})
})
}
}
func TestRefreshNewerReport(t *testing.T) {
cmpDiff := func(want, got any) string {
return gcmp.Diff(want, got,
gcmpopts.EquateComparable(netip.Addr{}, netip.Prefix{}))
}
peers := []tailcfg.NodeView{
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
}
synctest.Test(t, func(t *testing.T) {
self := makeNode(99, withName("self"))
// This is the “older” report where all the peers are online
// that we expect to get clobbered.
b := newStubBackend(self, peers)
t.Cleanup(func() { b.Close() })
c, err := routecheck.NewClient(t.Context(), t.Logf, b, b, b)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
older, err := c.Refresh(t.Context(), routecheck.DefaultTimeout)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
// This is the “newer” report where some of the peers are online.
// Run this one before the actual test and fake its Done time.
time.Sleep(1 * time.Minute)
b.gone = set.Of(tailcfg.NodeID(11), tailcfg.NodeID(22))
newer, err := c.Refresh(t.Context(), routecheck.DefaultTimeout)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if !older.Done.Before(newer.Done) {
t.Errorf("newer report didn’t clobber older")
}
newer.Done = newer.Done.Add(1 * time.Hour)
// Check that newer reports don’t get clobbered
// by simulating a run that happened between older and newer
// where only one node went offline.
b.gone = set.Of(tailcfg.NodeID(11))
between, err := c.Refresh(t.Context(), routecheck.DefaultTimeout)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if diff := cmpDiff(between, newer); diff != "" {
t.Errorf("newer report was clobbered, -newer +between:\n%s", diff)
}
})
}
func TestRoutersByPrefix(t *testing.T) {
type routersByPrefix map[netip.Prefix][]tailcfg.NodeID
simplify := func(rs routecheck.RoutersByPrefix) routersByPrefix {
out := make(routersByPrefix, len(rs))
for p, ns := range rs {
for _, n := range ns {
out[p] = append(out[p], n.ID())
}
slices.Sort(out[p])
}
return out
}
for _, tt := range []struct {
name string
peers []tailcfg.NodeView
want routersByPrefix
}{
{
name: "no-peers",
peers: []tailcfg.NodeView{},
want: routersByPrefix{},
},
{
name: "no-routers",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
},
want: routersByPrefix{},
},
{
name: "one-exit-node",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(11, withName("exit11"), withExitRoutes()),
},
want: routersByPrefix{
netip.MustParsePrefix("0.0.0.0/0"): {11},
netip.MustParsePrefix("::/0"): {11},
},
},
{
name: "overlapping-exit-nodes",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
},
want: routersByPrefix{
netip.MustParsePrefix("0.0.0.0/0"): {11, 12},
netip.MustParsePrefix("::/0"): {11, 12},
},
},
{
name: "one-subnet-router",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
},
want: routersByPrefix{
netip.MustParsePrefix("192.168.1.0/24"): {21},
netip.MustParsePrefix("2002:c000:0100::/48"): {21},
},
},
{
name: "overlapping-subnet-routers",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
},
want: routersByPrefix{
netip.MustParsePrefix("192.168.1.0/24"): {21, 22},
netip.MustParsePrefix("2002:c000:0100::/48"): {21, 22},
},
},
{
name: "disjoint-subnet-routers",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48"))),
},
want: routersByPrefix{
netip.MustParsePrefix("192.168.1.0/24"): {21},
netip.MustParsePrefix("2002:c000:0100::/48"): {21},
netip.MustParsePrefix("192.168.2.0/24"): {22},
netip.MustParsePrefix("2002:c000:0200::/48"): {22},
},
},
{
name: "multiple-routes",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48")),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48")),
withRoutes(netip.MustParsePrefix("192.168.3.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0300::/48"))),
makeNode(23, withName("subnet23"),
withRoutes(netip.MustParsePrefix("192.168.3.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0300::/48")),
withRoutes(netip.MustParsePrefix("192.168.4.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0400::/48"))),
},
want: routersByPrefix{
netip.MustParsePrefix("192.168.1.0/24"): {21},
netip.MustParsePrefix("2002:c000:0100::/48"): {21},
netip.MustParsePrefix("192.168.2.0/24"): {21, 22},
netip.MustParsePrefix("2002:c000:0200::/48"): {21, 22},
netip.MustParsePrefix("192.168.3.0/24"): {22, 23},
netip.MustParsePrefix("2002:c000:0300::/48"): {22, 23},
netip.MustParsePrefix("192.168.4.0/24"): {23},
netip.MustParsePrefix("2002:c000:0400::/48"): {23},
},
},
{
name: "both-exit-nodes-and-routers",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(11, withName("exit11"), withExitRoutes()),
makeNode(12, withName("exit12"), withExitRoutes()),
makeNode(21, withName("subnet21"),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48")),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48"))),
makeNode(22, withName("subnet22"),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48")),
withRoutes(netip.MustParsePrefix("192.168.3.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0300::/48"))),
},
want: routersByPrefix{
netip.MustParsePrefix("0.0.0.0/0"): {11, 12},
netip.MustParsePrefix("::/0"): {11, 12},
netip.MustParsePrefix("192.168.1.0/24"): {21},
netip.MustParsePrefix("2002:c000:0100::/48"): {21},
netip.MustParsePrefix("192.168.2.0/24"): {21, 22},
netip.MustParsePrefix("2002:c000:0200::/48"): {21, 22},
netip.MustParsePrefix("192.168.3.0/24"): {22},
netip.MustParsePrefix("2002:c000:0300::/48"): {22},
},
},
{
name: "mixed-nodes",
peers: []tailcfg.NodeView{
makeNode(1, withName("peer1")),
makeNode(31, withName("router31"),
withExitRoutes(),
withRoutes(netip.MustParsePrefix("192.168.1.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0100::/48")),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48"))),
makeNode(32, withName("router32"),
withExitRoutes(),
withRoutes(netip.MustParsePrefix("192.168.2.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0200::/48")),
withRoutes(netip.MustParsePrefix("192.168.3.0/24")),
withRoutes(netip.MustParsePrefix("2002:c000:0300::/48"))),
},
want: routersByPrefix{
netip.MustParsePrefix("0.0.0.0/0"): {31, 32},
netip.MustParsePrefix("::/0"): {31, 32},
netip.MustParsePrefix("192.168.1.0/24"): {31},
netip.MustParsePrefix("2002:c000:0100::/48"): {31},
netip.MustParsePrefix("192.168.2.0/24"): {31, 32},
netip.MustParsePrefix("2002:c000:0200::/48"): {31, 32},
netip.MustParsePrefix("192.168.3.0/24"): {32},
netip.MustParsePrefix("2002:c000:0300::/48"): {32},
},
},
} {
t.Run(tt.name, func(t *testing.T) {
self := makeNode(99, withName("self"))
b := newStubBackend(self, tt.peers)
t.Cleanup(func() { b.Close() })
c, err := routecheck.NewClient(t.Context(), t.Logf, b, b, b)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
got := simplify(c.RoutersByPrefix())
if !maps.EqualFunc(got, tt.want, slices.Equal) {
t.Errorf("got %+v, want %+v", got, tt.want)
}
})
}
}
type nodeOptFunc func(*tailcfg.Node)
func makeNode(id tailcfg.NodeID, opts ...nodeOptFunc) tailcfg.NodeView {
addresses := []netip.Prefix{
netip.MustParsePrefix(fmt.Sprintf("192.168.0.%d/32", id)),
netip.MustParsePrefix(fmt.Sprintf("fd7a:115c:a1e0::%d/128", id)),
}
node := &tailcfg.Node{
ID: id,
StableID: tailcfg.StableNodeID(fmt.Sprintf("stable%d", id)),
Name: fmt.Sprintf("node%d", id),
Online: new(true),
MachineAuthorized: true,
HomeDERP: int(id),
Addresses: addresses,
AllowedIPs: addresses,
}
for _, opt := range opts {
opt(node)
}
return node.View()
}
func withExitRoutes() nodeOptFunc {
return withRoutes(tsaddr.ExitRoutes()...)
}
func withName(name string) nodeOptFunc {
return func(n *tailcfg.Node) {
n.Name = name
}
}
func withRoutes(routes ...netip.Prefix) nodeOptFunc {
return func(n *tailcfg.Node) {
n.AllowedIPs = append(n.AllowedIPs, routes...)
}
}
var _ routecheck.NodeBackender = &stubBackend{}
var _ routecheck.NodeBackend = &stubBackend{}
var _ routecheck.NetMapper = &stubBackend{}
var _ routecheck.Pinger = &stubBackend{}
type stubBackend struct {
self tailcfg.NodeView
peers []tailcfg.NodeView
gone set.Set[tailcfg.NodeID]
delay context.Context
cancel context.CancelFunc
donef atomic.Pointer[func()]
}
type backendOptFunc func(*stubBackend)
func newStubBackend(self tailcfg.NodeView, peers []tailcfg.NodeView, opts ...backendOptFunc) *stubBackend {
if !self.Valid() {
panic("invalid self")
}
delay, cancel := context.WithTimeout(context.Background(), 0) // No delay
b := &stubBackend{
self: self,
peers: slices.Clone(peers),
delay: delay,
cancel: cancel,
}
for _, opt := range opts {
opt(b)
}
return b
}
func (b *stubBackend) Close() error {
if b.cancel != nil {
b.cancel()
}
return nil
}
func (b *stubBackend) NetMapNoPeers() *netmap.NetworkMap {
if b.delay.Err() == nil {
// Simulate the delay between startup and receiving the NetMap.
return nil
}
return &netmap.NetworkMap{
SelfNode: b.self,
Peers: nil, // No peers.
}
}
func (b *stubBackend) NetMapWithPeers() *netmap.NetworkMap {
nm := b.NetMapNoPeers()
if nm != nil {
nm.Peers = b.peers
}
return nm
}
func (nb *stubBackend) NodeBackend() routecheck.NodeBackend {
return nb
}
func (nb *stubBackend) Self() tailcfg.NodeView {
return nb.self
}
func (nb *stubBackend) Peers() []tailcfg.NodeView {
return nb.peers
}
func (b *stubBackend) Ping(ip netip.Addr, pingType tailcfg.PingType, size int, cb func(*ipnstate.PingResult)) {
// Does the IP address match one of the peers’ addresses?
for _, n := range b.peers {
for _, a := range n.Addresses().All() {
if a.Addr() != ip {
continue
}
if b.gone.Contains(n.ID()) {
continue
}
go cb(&ipnstate.PingResult{
IP: ip.String(),
NodeIP: ip.String(),
NodeName: n.Name(),
LatencySeconds: 0.01,
})
}
}
}
func withDelay(t *testing.T, d time.Duration) backendOptFunc {
return func(b *stubBackend) {
t.Helper()
var stopf func() bool
ctx, cancel := context.WithTimeout(t.Context(), d)
stopf = context.AfterFunc(ctx, func() {
if donef := b.donef.Load(); donef != nil {
(*donef)()
}
cancel()
stopf()
})
b.delay = ctx
}
}
func withGone(t *testing.T, gone ...tailcfg.NodeID) backendOptFunc {
return func(b *stubBackend) {
t.Helper()
b.gone = set.SetOf(gone)
}
}
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