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28801674a6fec926d19254938263318581894da4
tailscale/net/routecheck/routecheck_test.go
T
Simon Law 28801674a6 net/routecheck: introduce new package for checking peer reachability (#19639) 
The routecheck package parallels the netcheck package, where the
former checks routes and routers while the latter checks networks.
Like netcheck, it compiles reports for other systems to consume.

Historically, the client has never known whether a peer is actually
reachable. Most of the time this doesn’t matter, since the client will
want to establish a WireGuard tunnel to any given destination.
However, if the client needs to choose between two or more nodes,
then it should try to choose a node that it can reach.

Suggested exit nodes are one such example, where the client filters
out any nodes that aren’t connected to the control plane. Sometimes an
exit node will get disconnected from the control plane: when the
network between the two is unreliable or when the exit node is too
busy to keep its control connection alive. In these cases, Control
disables the Node.Online flag for the exit node and broadcasts this
across the tailnet. Arguably, the client should never have relied on
this flag, since it only makes sense in the admin console.

This patch implements an initial routecheck client that can probe
every node that your client knows about. You should not ping scan your
visible tailnet, this method is for debugging only.

This patch also introduces a new OnNetMapToggle hook, which fires when
the netmap transitions from nil to non-nil, or vice versa. This
happens either when the client receives its first MapResponse after
connecting to the control plane, or when it clears the netmap while it
is disconnecting. Routecheck uses this to wait for a valid netmap
so it knows which peers to probe.

Updates #17366
Updates tailscale/corp#33033

Signed-off-by: Simon Law <sfllaw@tailscale.com>
2026-06-01 10:33:08 -07:00

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// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause
package routecheck_test
import (
"fmt"
"maps"
"net/netip"
"slices"
"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 TestReport(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: "before-netmap",
init: true,
want: nil,
},
{
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) {
// The backend is initialized without a NetMap.
b := newStubBackend(tailcfg.NodeView{}, nil, withGone(tt.gone...))
if !tt.init {
self := makeNode(99, withName("self"))
b = newStubBackend(self, tt.peers, withGone(tt.gone...))
}
c, err := routecheck.NewClient(t.Logf, b, b, b)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
got := c.Report()
now := time.Now() // synctest will freeze time.
var want *routecheck.Report
peers := makeDB(tt.peers)
if !tt.init {
want = &routecheck.Report{
Done: now,
}
for _, nid := range tt.want {
mak.Set(&want.Reachable, nid, peers[nid])
}
}
if diff := cmpDiff(want, got); diff != "" {
t.Errorf("-want +got:\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)
c, err := routecheck.NewClient(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]
}
type backendOptFunc func(*stubBackend)
func newStubBackend(self tailcfg.NodeView, peers []tailcfg.NodeView, opts ...backendOptFunc) *stubBackend {
b := &stubBackend{
self: self,
peers: slices.Clone(peers),
}
for _, opt := range opts {
opt(b)
}
return b
}
func (b *stubBackend) NetMapNoPeers() *netmap.NetworkMap {
if !b.self.Valid() {
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 withGone(gone ...tailcfg.NodeID) backendOptFunc {
return func(b *stubBackend) {
b.gone = set.SetOf(gone)
}
}
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