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ipn/ipnlocal,net/routemanager: keep a routemanager.RouteManager updated per node

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Give nodeBackend a RouteManager and keep it in sync as routing
inputs change: full netmaps resync the whole peer set (removals plus
no-op-cheap upserts), incremental netmap deltas mirror their peer
upserts and removes into the same mutation batch, and
authReconfigLocked pushes the routing-relevant prefs (exit node,
subnet route acceptance, OneCGNAT) after resolving the exit node's
stable ID to its current numeric node ID.

A selected exit node that doesn't resolve to a current peer (a
nonexistent node, or MDM's "auto:any" placeholder awaiting
resolution) is not the same as no exit node: per the long-standing
ipn.Prefs.ExitNodeID contract, it blackholes internet traffic rather
than letting it escape to the local network. RouteManager's Prefs
gains an ExitNodeSelected bit so its OS route set keeps the default
routes in that case, with no outbound peer to carry them, matching
what routerConfigLocked does today, as pinned by TestRouterConfigExitNodeBlackhole in the previous commit.

All mutations happen with nodeBackend.mu held, satisfying the
RouteManager's serialized Begin/Commit contract.

Nothing consumes its snapshots yet; the wgengine data plane and OS
router wiring come next.

Updates #12542

Change-Id: I677b6b2c9efb8e41b3d27071bd9db73e01640d3b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2026-07-13 10:20:54 -07:00
committed by Brad Fitzpatrick
parent ce050f1ca1
commit ff1c7ef23c
11 changed files with 254 additions and 5 deletions
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net/routemanager/routemanager_test.go
+45
View File
@@ -895,3 +895,48 @@ func TestExtraAllowedIPsPeerLifecycle(t *testing.T) {
wantOutbound(t, rm, "fe80::1234", k1, true)
wantOSRoutes(t, rm, "100.64.0.1/32", "fd7a:115c:a1e0::/48")
}
// Tests that the exit routes stay in the OS route set whenever an
// exit node is selected, even one that resolves to no current peer
// (Prefs.ExitNodeSelected with a zero ExitNodeID), so internet
// traffic is blackholed rather than escaping to the local network.
// This mirrors the long-standing behavior documented on
// ipn.Prefs.ExitNodeID and relied on by MDM's "auto:any" placeholder.
func TestExitNodeBlackhole(t *testing.T) {
rm := New(t.Logf)
exitPeer := peer1()
exitPeer.Routes = tsaddr.ExitRoutes()
commit(rm, func(m *Mutation) { m.upsertPeer(exitPeer) })
// No exit node selected: no default routes, no outbound winner.
wantOSRoutes(t, rm, "100.64.0.1/32", "fd7a:115c:a1e0::/48")
wantOutbound(t, rm, "8.8.8.8", key.NodePublic{}, false)
// A resolved exit node carries the default routes.
commit(rm, func(m *Mutation) {
m.SetPrefs(Prefs{ExitNodeID: 1, ExitNodeSelected: true})
})
wantOSRoutes(t, rm, "100.64.0.1/32", "fd7a:115c:a1e0::/48", "0.0.0.0/0", "::/0")
wantOutbound(t, rm, "8.8.8.8", k1, true)
// An unresolved exit node (nonexistent, or not yet resolved)
// keeps the default routes with no outbound winner: a blackhole.
commit(rm, func(m *Mutation) {
m.SetPrefs(Prefs{ExitNodeID: 0, ExitNodeSelected: true})
})
wantOSRoutes(t, rm, "100.64.0.1/32", "fd7a:115c:a1e0::/48", "0.0.0.0/0", "::/0")
wantOutbound(t, rm, "8.8.8.8", key.NodePublic{}, false)
// Removing the exit-capable peer while still selected keeps the
// blackhole in place via the incremental path.
commit(rm, func(m *Mutation) {
m.SetPrefs(Prefs{ExitNodeID: 1, ExitNodeSelected: true})
})
commit(rm, func(m *Mutation) { m.RemovePeer(1) })
wantOSRoutes(t, rm, "0.0.0.0/0", "::/0")
wantOutbound(t, rm, "8.8.8.8", key.NodePublic{}, false)
// Deselecting the exit node removes the default routes.
commit(rm, func(m *Mutation) { m.SetPrefs(Prefs{}) })
wantOSRoutes(t, rm)
}