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net/netmon, wgengine/userspace: purge ChangeDelta.Major and address TODOs (#17823)

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updates tailscale/corp#33891

Addresses several older the TODO's in netmon.  This removes the 
Major flag precomputes the ChangeDelta state, rather than making
consumers of ChangeDeltas sort that out themselves.   We're also seeing
a lot of ChangeDelta's being flagged as "Major" when they are
not interesting, triggering rebinds in wgengine that are not needed.  This
cleans that up and adds a host of additional tests.

The dependencies are cleaned, notably removing dependency on netmon
itself for calculating what is interesting, and what is not.  This includes letting
individual platforms set a bespoke global "IsInterestingInterface"
function.  This is only used on Darwin.

RebindRequired now roughly follows how "Major" was historically
calculated but includes some additional checks for various
uninteresting events such as changes in interface addresses that
shouldn't trigger a rebind.  This significantly reduces thrashing (by
roughly half on Darwin clients which switching between nics).   The individual
values that we roll  into RebindRequired are also exposed so that
components consuming netmap.ChangeDelta can ask more
targeted questions.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
This commit is contained in:
Jonathan Nobels
2025-12-17 12:32:40 -05:00
committed by GitHub
parent 0fd1670a59
commit 3e89068792
19 changed files with 754 additions and 273 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/netmon/netmon_test.go
+351 -31
View File
@@ -8,6 +8,7 @@ import (
"net"
"net/netip"
"reflect"
"strings"
"sync/atomic"
"testing"
"time"
@@ -138,7 +139,7 @@ func TestMonitorMode(t *testing.T) {
n := 0
mon.RegisterChangeCallback(func(d *ChangeDelta) {
n++
t.Logf("cb: changed=%v, ifSt=%v", d.Major, d.New)
t.Logf("cb: changed=%v, ifSt=%v", d.RebindLikelyRequired, d.CurrentState())
})
mon.Start()
<-done
@@ -149,24 +150,22 @@ func TestMonitorMode(t *testing.T) {
mon.Start()
eventbustest.Expect(tw, func(event *ChangeDelta) (bool, error) {
n++
t.Logf("cb: changed=%v, ifSt=%v", event.Major, event.New)
t.Logf("cb: changed=%v, ifSt=%v", event.RebindLikelyRequired, event.CurrentState())
return false, nil // Return false, indicating we wanna look for more events
})
t.Logf("%v events", n)
}
}
// tests (*State).IsMajorChangeFrom
func TestIsMajorChangeFrom(t *testing.T) {
// tests (*ChangeDelta).RebindRequired
func TestRebindRequired(t *testing.T) {
// s1 cannot be nil by definition
tests := []struct {
name string
s1, s2 *State
want bool
name string
s1, s2 *State
tsIfName string
want bool
}{
{
name: "eq_nil",
want: false,
},
{
name: "nil_mix",
s2: new(State),
@@ -188,6 +187,110 @@ func TestIsMajorChangeFrom(t *testing.T) {
},
want: false,
},
{
name: "new-with-no-addr",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
"bar": {},
},
},
want: false,
},
{
name: "ignore-tailscale-interface-appearing",
tsIfName: "tailscale0",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
"tailscale0": {netip.MustParsePrefix("100.69.4.20/32")},
},
},
want: false,
},
{
name: "ignore-tailscale-interface-disappearing",
tsIfName: "tailscale0",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
"tailscale0": {netip.MustParsePrefix("100.69.4.20/32")},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
},
},
want: false,
},
{
name: "new-with-multicast-addr",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
"bar": {netip.MustParsePrefix("224.0.0.1/32")},
},
},
want: false,
},
{
name: "old-with-addr-dropped",
s1: &State{
DefaultRouteInterface: "bar",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
"bar": {netip.MustParsePrefix("192.168.0.1/32")},
},
},
s2: &State{
DefaultRouteInterface: "bar",
InterfaceIPs: map[string][]netip.Prefix{
"bar": {netip.MustParsePrefix("192.168.0.1/32")},
},
},
want: true,
},
{
name: "old-with-no-addr-dropped",
s1: &State{
DefaultRouteInterface: "bar",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {},
"bar": {netip.MustParsePrefix("192.168.0.1/16")},
},
},
s2: &State{
DefaultRouteInterface: "bar",
InterfaceIPs: map[string][]netip.Prefix{
"bar": {netip.MustParsePrefix("192.168.0.1/16")},
},
},
want: false,
},
{
name: "default-route-changed",
s1: &State{
@@ -221,6 +324,8 @@ func TestIsMajorChangeFrom(t *testing.T) {
want: true,
},
{
// (barnstar) TODO: ULA addresses are only useful in some contexts,
// so maybe this shouldn't trigger rebinds after all? Needs more thought.
name: "ipv6-ula-addressed-appeared",
s1: &State{
DefaultRouteInterface: "foo",
@@ -233,15 +338,147 @@ func TestIsMajorChangeFrom(t *testing.T) {
InterfaceIPs: map[string][]netip.Prefix{
"foo": {
netip.MustParsePrefix("10.0.1.2/16"),
// Brad saw this address coming & going on his home LAN, possibly
// via an Apple TV Thread routing advertisement? (Issue 9040)
netip.MustParsePrefix("fd15:bbfa:c583:4fce:f4fb:4ff:fe1a:4148/64"),
},
},
},
want: true, // TODO(bradfitz): want false (ignore the IPv6 ULA address on foo)
want: true,
},
{
// (barnstar) TODO: ULA addresses are only useful in some contexts,
// so maybe this shouldn't trigger rebinds after all? Needs more thought.
name: "ipv6-ula-addressed-disappeared",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {
netip.MustParsePrefix("10.0.1.2/16"),
netip.MustParsePrefix("fd15:bbfa:c583:4fce:f4fb:4ff:fe1a:4148/64"),
},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
},
},
want: true,
},
{
name: "ipv6-link-local-addressed-appeared",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {netip.MustParsePrefix("10.0.1.2/16")},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {
netip.MustParsePrefix("10.0.1.2/16"),
netip.MustParsePrefix("fe80::f242:25ff:fe64:b280/64"),
},
},
},
want: false,
},
{
name: "ipv6-addressed-changed",
s1: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {
netip.MustParsePrefix("10.0.1.2/16"),
netip.MustParsePrefix("2001::f242:25ff:fe64:b280/64"),
netip.MustParsePrefix("fe80::f242:25ff:fe64:b280/64"),
},
},
},
s2: &State{
DefaultRouteInterface: "foo",
InterfaceIPs: map[string][]netip.Prefix{
"foo": {
netip.MustParsePrefix("10.0.1.2/16"),
netip.MustParsePrefix("2001::beef:8bad:f00d:b280/64"),
netip.MustParsePrefix("fe80::f242:25ff:fe64:b280/64"),
},
},
},
want: true,
},
{
name: "have-addr-changed",
s1: &State{
HaveV6: false,
HaveV4: false,
},
s2: &State{
HaveV6: true,
HaveV4: true,
},
want: true,
},
{
name: "have-addr-unchanged",
s1: &State{
HaveV6: true,
HaveV4: true,
},
s2: &State{
HaveV6: true,
HaveV4: true,
},
want: false,
},
{
name: "new-is-less-expensive",
s1: &State{
IsExpensive: true,
},
s2: &State{
IsExpensive: false,
},
want: true,
},
{
name: "new-is-more-expensive",
s1: &State{
IsExpensive: false,
},
s2: &State{
IsExpensive: true,
},
want: false,
},
{
name: "uninteresting-interface-added",
s1: &State{
DefaultRouteInterface: "bar",
InterfaceIPs: map[string][]netip.Prefix{
"bar": {netip.MustParsePrefix("192.168.0.1/16")},
},
},
s2: &State{
DefaultRouteInterface: "bar",
InterfaceIPs: map[string][]netip.Prefix{
"bar": {netip.MustParsePrefix("192.168.0.1/16")},
"boring": {netip.MustParsePrefix("fd7a:115c:a1e0:ab12:4843:cd96:625e:13ce/64")},
},
},
want: false,
},
}
withIsInterestingInterface(t, func(ni Interface, pfxs []netip.Prefix) bool {
return !strings.HasPrefix(ni.Name, "boring")
})
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
// Populate dummy interfaces where missing.
@@ -258,16 +495,111 @@ func TestIsMajorChangeFrom(t *testing.T) {
}
}
var m Monitor
m.om = &testOSMon{
Interesting: func(name string) bool { return true },
cd, err := NewChangeDelta(tt.s1, tt.s2, false, tt.tsIfName, true)
if err != nil {
t.Fatalf("NewChangeDelta error: %v", err)
}
if got := m.IsMajorChangeFrom(tt.s1, tt.s2); got != tt.want {
t.Errorf("IsMajorChange = %v; want %v", got, tt.want)
_ = cd // in case we need it later
if got := cd.RebindLikelyRequired; got != tt.want {
t.Errorf("RebindRequired = %v; want %v", got, tt.want)
}
})
}
}
func withIsInterestingInterface(t *testing.T, fn func(Interface, []netip.Prefix) bool) {
t.Helper()
old := IsInterestingInterface
IsInterestingInterface = fn
t.Cleanup(func() { IsInterestingInterface = old })
}
func TestIncludesRoutableIP(t *testing.T) {
routable := []netip.Prefix{
netip.MustParsePrefix("1.2.3.4/32"),
netip.MustParsePrefix("10.0.0.1/24"), // RFC1918 IPv4 (private)
netip.MustParsePrefix("172.16.0.1/12"), // RFC1918 IPv4 (private)
netip.MustParsePrefix("192.168.1.1/24"), // RFC1918 IPv4 (private)
netip.MustParsePrefix("fd15:dead:beef::1/64"), // IPv6 ULA
netip.MustParsePrefix("2001:db8::1/64"), // global IPv6
}
nonRoutable := []netip.Prefix{
netip.MustParsePrefix("ff00::/8"), // multicast IPv6 (should be filtered)
netip.MustParsePrefix("fe80::1/64"), // link-local IPv6
netip.MustParsePrefix("::1/128"), // loopback IPv6
netip.MustParsePrefix("::/128"), // unspecified IPv6
netip.MustParsePrefix("224.0.0.1/32"), // multicast IPv4
netip.MustParsePrefix("127.0.0.1/32"), // loopback IPv4
}
got, want := filterRoutableIPs(
append(nonRoutable, routable...),
), routable
if !reflect.DeepEqual(got, want) {
t.Fatalf("filterRoutableIPs returned %v; want %v", got, want)
}
}
func TestPrefixesEqual(t *testing.T) {
tests := []struct {
name string
a, b []netip.Prefix
want bool
}{
{
name: "empty",
a: []netip.Prefix{},
b: []netip.Prefix{},
want: true,
},
{
name: "single-equal",
a: []netip.Prefix{netip.MustParsePrefix("10.0.0.1/24")},
b: []netip.Prefix{netip.MustParsePrefix("10.0.0.1/24")},
want: true,
},
{
name: "single-different",
a: []netip.Prefix{netip.MustParsePrefix("10.0.0.1/24")},
b: []netip.Prefix{netip.MustParsePrefix("10.0.0.2/24")},
want: false,
},
{
name: "unordered-equal",
a: []netip.Prefix{
netip.MustParsePrefix("10.0.0.1/24"),
netip.MustParsePrefix("10.0.2.1/24"),
},
b: []netip.Prefix{
netip.MustParsePrefix("10.0.2.1/24"),
netip.MustParsePrefix("10.0.0.1/24"),
},
want: true,
},
{
name: "subset",
a: []netip.Prefix{
netip.MustParsePrefix("10.0.2.1/24"),
},
b: []netip.Prefix{
netip.MustParsePrefix("10.0.2.1/24"),
netip.MustParsePrefix("10.0.0.1/24"),
},
want: false,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got := prefixesEqual(tt.a, tt.b)
if got != tt.want {
t.Errorf("prefixesEqual(%v, %v) = %v; want %v", tt.a, tt.b, got, tt.want)
}
})
}
}
func TestForeachInterface(t *testing.T) {
tests := []struct {
name string
@@ -307,15 +639,3 @@ func TestForeachInterface(t *testing.T) {
})
}
}
type testOSMon struct {
osMon
Interesting func(name string) bool
}
func (m *testOSMon) IsInterestingInterface(name string) bool {
if m.Interesting == nil {
return true
}
return m.Interesting(name)
}