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ipn/ipnlocal: add traffic steering support to exit-node suggestions (#16527)

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When `tailscale exit-node suggest` contacts the LocalAPI for a
suggested exit node, the client consults its netmap for peers that
contain the `suggest-exit-node` peercap. It currently uses a series of
heuristics to determine the exit node to suggest.

When the `traffic-steering` feature flag is enabled on its tailnet,
the client will defer to Control’s priority scores for a particular
peer. These scores, in `tailcfg.Hostinfo.Location.Priority`, were
historically only used for Mullvad exit nodes, but they have now been
extended to score any peer that could host a redundant resource.

Client capability version 119 is the earliest client that understands
these traffic steering scores. Control tells the client to switch to
rely on these scores by adding `tailcfg.NodeAttrTrafficSteering` to
its `AllCaps`.

Updates tailscale/corp#29966

Signed-off-by: Simon Law <sfllaw@tailscale.com>
This commit is contained in:
Simon Law
2025-07-10 22:15:55 -07:00
committed by GitHub
parent bd29a1c8c1
commit c18ba4470b
3 changed files with 546 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ipn/ipnlocal/local_test.go
+417
View File
@@ -4229,6 +4229,23 @@ func withLocation(loc tailcfg.LocationView) peerOptFunc {
}
}
func withLocationPriority(pri int) peerOptFunc {
return func(n *tailcfg.Node) {
var hi *tailcfg.Hostinfo
if n.Hostinfo.Valid() {
hi = n.Hostinfo.AsStruct()
} else {
hi = new(tailcfg.Hostinfo)
}
if hi.Location == nil {
hi.Location = new(tailcfg.Location)
}
hi.Location.Priority = pri
n.Hostinfo = hi.View()
}
}
func withExitRoutes() peerOptFunc {
return func(n *tailcfg.Node) {
n.AllowedIPs = append(n.AllowedIPs, tsaddr.ExitRoutes()...)
@@ -4895,6 +4912,406 @@ func TestSuggestExitNodeLongLatDistance(t *testing.T) {
}
}
func TestSuggestExitNodeTrafficSteering(t *testing.T) {
city := &tailcfg.Location{
Country: "Canada",
CountryCode: "CA",
City: "Montreal",
CityCode: "MTR",
Latitude: 45.5053,
Longitude: -73.5525,
}
noLatLng := &tailcfg.Location{
Country: "Canada",
CountryCode: "CA",
City: "Montreal",
CityCode: "MTR",
}
selfNode := tailcfg.Node{
ID: 0, // randomness is seeded off NetMap.SelfNode.ID
Addresses: []netip.Prefix{
netip.MustParsePrefix("100.64.1.1/32"),
netip.MustParsePrefix("fe70::1/128"),
},
CapMap: tailcfg.NodeCapMap{
tailcfg.NodeAttrTrafficSteering: []tailcfg.RawMessage{},
},
}
for _, tt := range []struct {
name string
netMap *netmap.NetworkMap
lastExit tailcfg.StableNodeID
allowPolicy []tailcfg.StableNodeID
wantID tailcfg.StableNodeID
wantName string
wantLoc *tailcfg.Location
wantPri int
wantErr error
}{
{
name: "no-netmap",
netMap: nil,
wantErr: ErrNoNetMap,
},
{
name: "no-nodes",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{},
},
wantID: "",
},
{
name: "no-exit-nodes",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1),
},
},
wantID: "",
},
{
name: "exit-node-without-suggestion",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes()),
},
},
wantID: "",
},
{
name: "suggested-exit-node-without-routes",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withSuggest()),
},
},
wantID: "",
},
{
name: "suggested-exit-node",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest()),
},
},
wantID: "stable1",
wantName: "peer1",
},
{
name: "many-suggested-exit-nodes",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest()),
makePeer(2,
withExitRoutes(),
withSuggest()),
makePeer(3,
withExitRoutes(),
withSuggest()),
makePeer(4,
withExitRoutes(),
withSuggest()),
},
},
wantID: "stable3",
wantName: "peer3",
},
{
name: "suggested-exit-node-was-last-suggested",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest()),
makePeer(2,
withExitRoutes(),
withSuggest()),
makePeer(3,
withExitRoutes(),
withSuggest()),
makePeer(4,
withExitRoutes(),
withSuggest()),
},
},
lastExit: "stable2", // overrides many-suggested-exit-nodes
wantID: "stable2",
wantName: "peer2",
},
{
name: "suggested-exit-node-was-never-suggested",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest()),
makePeer(2,
withExitRoutes(),
withSuggest()),
makePeer(3,
withExitRoutes(),
withSuggest()),
makePeer(4,
withExitRoutes(),
withSuggest()),
},
},
lastExit: "stable10",
wantID: "stable3", // matches many-suggested-exit-nodes
wantName: "peer3",
},
{
name: "exit-nodes-with-and-without-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocationPriority(1)),
makePeer(2,
withExitRoutes(),
withSuggest()),
},
},
wantID: "stable1",
wantName: "peer1",
wantPri: 1,
},
{
name: "exit-nodes-without-and-with-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest()),
makePeer(2,
withExitRoutes(),
withSuggest(),
withLocationPriority(1)),
},
},
wantID: "stable2",
wantName: "peer2",
wantPri: 1,
},
{
name: "exit-nodes-with-negative-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocationPriority(-1)),
makePeer(2,
withExitRoutes(),
withSuggest(),
withLocationPriority(-2)),
makePeer(3,
withExitRoutes(),
withSuggest(),
withLocationPriority(-3)),
makePeer(4,
withExitRoutes(),
withSuggest(),
withLocationPriority(-4)),
},
},
wantID: "stable1",
wantName: "peer1",
wantPri: -1,
},
{
name: "exit-nodes-no-priority-beats-negative-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocationPriority(-1)),
makePeer(2,
withExitRoutes(),
withSuggest(),
withLocationPriority(-2)),
makePeer(3,
withExitRoutes(),
withSuggest()),
},
},
wantID: "stable3",
wantName: "peer3",
},
{
name: "exit-nodes-same-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocationPriority(1)),
makePeer(2,
withExitRoutes(),
withSuggest(),
withLocationPriority(2)), // top
makePeer(3,
withExitRoutes(),
withSuggest(),
withLocationPriority(1)),
makePeer(4,
withExitRoutes(),
withSuggest(),
withLocationPriority(2)), // top
makePeer(5,
withExitRoutes(),
withSuggest(),
withLocationPriority(2)), // top
makePeer(6,
withExitRoutes(),
withSuggest()),
makePeer(7,
withExitRoutes(),
withSuggest(),
withLocationPriority(2)), // top
},
},
wantID: "stable5",
wantName: "peer5",
wantPri: 2,
},
{
name: "suggested-exit-node-with-city",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocation(city.View())),
},
},
wantID: "stable1",
wantName: "peer1",
wantLoc: city,
},
{
name: "suggested-exit-node-with-city-and-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocation(city.View()),
withLocationPriority(1)),
},
},
wantID: "stable1",
wantName: "peer1",
wantLoc: city,
wantPri: 1,
},
{
name: "suggested-exit-node-without-latlng",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocation(noLatLng.View())),
},
},
wantID: "stable1",
wantName: "peer1",
wantLoc: noLatLng,
},
{
name: "suggested-exit-node-without-latlng-with-priority",
netMap: &netmap.NetworkMap{
SelfNode: selfNode.View(),
Peers: []tailcfg.NodeView{
makePeer(1,
withExitRoutes(),
withSuggest(),
withLocation(noLatLng.View()),
withLocationPriority(1)),
},
},
wantID: "stable1",
wantName: "peer1",
wantLoc: noLatLng,
wantPri: 1,
},
} {
t.Run(tt.name, func(t *testing.T) {
var allowList set.Set[tailcfg.StableNodeID]
if tt.allowPolicy != nil {
allowList = set.SetOf(tt.allowPolicy)
}
// HACK: NetMap.AllCaps is populated by Control:
if tt.netMap != nil {
caps := maps.Keys(tt.netMap.SelfNode.CapMap().AsMap())
tt.netMap.AllCaps = set.SetOf(slices.Collect(caps))
}
nb := newNodeBackend(t.Context(), eventbus.New())
defer nb.shutdown(errShutdown)
nb.SetNetMap(tt.netMap)
got, err := suggestExitNodeUsingTrafficSteering(nb, tt.lastExit, allowList)
if tt.wantErr == nil && err != nil {
t.Fatalf("err=%v, want nil", err)
}
if tt.wantErr != nil && !errors.Is(err, tt.wantErr) {
t.Fatalf("err=%v, want %v", err, tt.wantErr)
}
if got.Name != tt.wantName {
t.Errorf("name=%q, want %q", got.Name, tt.wantName)
}
if got.ID != tt.wantID {
t.Errorf("ID=%q, want %q", got.ID, tt.wantID)
}
wantLoc := tt.wantLoc
if tt.wantPri != 0 {
if wantLoc == nil {
wantLoc = new(tailcfg.Location)
}
wantLoc.Priority = tt.wantPri
}
if diff := cmp.Diff(got.Location.AsStruct(), wantLoc); diff != "" {
t.Errorf("location mismatch (+want -got)\n%s", diff)
}
})
}
}
func TestMinLatencyDERPregion(t *testing.T) {
tests := []struct {
name string