tka: Checkpoint every 50 updates

Signed-off-by: Tom DNetto <tom@tailscale.com>
This commit is contained in:
Tom DNetto 2022-09-22 11:23:21 -07:00 committed by Tom
parent 8a0cb4ef20
commit e3beb4429f
4 changed files with 131 additions and 11 deletions

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@ -50,7 +50,6 @@ func (h AUMHash) IsZero() bool {
return h == (AUMHash{}) return h == (AUMHash{})
} }
// AUMKind describes valid AUM types. // AUMKind describes valid AUM types.
type AUMKind uint8 type AUMKind uint8

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@ -6,6 +6,7 @@ package tka
import ( import (
"fmt" "fmt"
"os"
"tailscale.com/types/tkatype" "tailscale.com/types/tkatype"
) )
@ -92,8 +93,62 @@ func (b *UpdateBuilder) SetKeyMeta(keyID tkatype.KeyID, meta map[string]string)
return b.mkUpdate(AUM{MessageKind: AUMUpdateKey, Meta: meta, KeyID: keyID}) return b.mkUpdate(AUM{MessageKind: AUMUpdateKey, Meta: meta, KeyID: keyID})
} }
func (b *UpdateBuilder) generateCheckpoint() error {
// Compute the checkpoint state.
state := b.a.state
for i, update := range b.out {
var err error
if state, err = state.applyVerifiedAUM(update); err != nil {
return fmt.Errorf("applying update %d: %v", i, err)
}
}
// Checkpoints cant specify a parent AUM.
state.LastAUMHash = nil
return b.mkUpdate(AUM{MessageKind: AUMCheckpoint, State: &state})
}
// checkpointEvery sets how often a checkpoint AUM should be generated.
const checkpointEvery = 50
// Finalize returns the set of update message to actuate the update. // Finalize returns the set of update message to actuate the update.
func (b *UpdateBuilder) Finalize() ([]AUM, error) { func (b *UpdateBuilder) Finalize(storage Chonk) ([]AUM, error) {
var (
needCheckpoint bool = true
cursor AUMHash = b.a.Head()
)
for i := len(b.out); i < checkpointEvery; i++ {
aum, err := storage.AUM(cursor)
if err != nil {
if err == os.ErrNotExist {
// The available chain is shorter than the interval to checkpoint at.
needCheckpoint = false
break
}
return nil, fmt.Errorf("reading AUM: %v", err)
}
if aum.MessageKind == AUMCheckpoint {
needCheckpoint = false
break
}
parent, hasParent := aum.Parent()
if !hasParent {
// We've hit the genesis update, so the chain is shorter than the interval to checkpoint at.
needCheckpoint = false
break
}
cursor = parent
}
if needCheckpoint {
if err := b.generateCheckpoint(); err != nil {
return nil, fmt.Errorf("generating checkpoint: %v", err)
}
}
// Check no AUMs were applied in the meantime
if len(b.out) > 0 { if len(b.out) > 0 {
if parent, _ := b.out[0].Parent(); parent != b.a.Head() { if parent, _ := b.out[0].Parent(); parent != b.a.Head() {
return nil, fmt.Errorf("updates no longer apply to head: based on %x but head is %x", parent, b.a.Head()) return nil, fmt.Errorf("updates no longer apply to head: based on %x but head is %x", parent, b.a.Head())

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@ -44,7 +44,7 @@ func TestAuthorityBuilderAddKey(t *testing.T) {
if err := b.AddKey(key2); err != nil { if err := b.AddKey(key2); err != nil {
t.Fatalf("AddKey(%v) failed: %v", key2, err) t.Fatalf("AddKey(%v) failed: %v", key2, err)
} }
updates, err := b.Finalize() updates, err := b.Finalize(storage)
if err != nil { if err != nil {
t.Fatalf("Finalize() failed: %v", err) t.Fatalf("Finalize() failed: %v", err)
} }
@ -78,7 +78,7 @@ func TestAuthorityBuilderRemoveKey(t *testing.T) {
if err := b.RemoveKey(key2.ID()); err != nil { if err := b.RemoveKey(key2.ID()); err != nil {
t.Fatalf("RemoveKey(%v) failed: %v", key2, err) t.Fatalf("RemoveKey(%v) failed: %v", key2, err)
} }
updates, err := b.Finalize() updates, err := b.Finalize(storage)
if err != nil { if err != nil {
t.Fatalf("Finalize() failed: %v", err) t.Fatalf("Finalize() failed: %v", err)
} }
@ -110,7 +110,7 @@ func TestAuthorityBuilderSetKeyVote(t *testing.T) {
if err := b.SetKeyVote(key.ID(), 5); err != nil { if err := b.SetKeyVote(key.ID(), 5); err != nil {
t.Fatalf("SetKeyVote(%v) failed: %v", key.ID(), err) t.Fatalf("SetKeyVote(%v) failed: %v", key.ID(), err)
} }
updates, err := b.Finalize() updates, err := b.Finalize(storage)
if err != nil { if err != nil {
t.Fatalf("Finalize() failed: %v", err) t.Fatalf("Finalize() failed: %v", err)
} }
@ -146,7 +146,7 @@ func TestAuthorityBuilderSetKeyMeta(t *testing.T) {
if err := b.SetKeyMeta(key.ID(), map[string]string{"b": "c"}); err != nil { if err := b.SetKeyMeta(key.ID(), map[string]string{"b": "c"}); err != nil {
t.Fatalf("SetKeyMeta(%v) failed: %v", key, err) t.Fatalf("SetKeyMeta(%v) failed: %v", key, err)
} }
updates, err := b.Finalize() updates, err := b.Finalize(storage)
if err != nil { if err != nil {
t.Fatalf("Finalize() failed: %v", err) t.Fatalf("Finalize() failed: %v", err)
} }
@ -191,7 +191,7 @@ func TestAuthorityBuilderMultiple(t *testing.T) {
if err := b.RemoveKey(key.ID()); err != nil { if err := b.RemoveKey(key.ID()); err != nil {
t.Fatalf("RemoveKey(%v) failed: %v", key, err) t.Fatalf("RemoveKey(%v) failed: %v", key, err)
} }
updates, err := b.Finalize() updates, err := b.Finalize(storage)
if err != nil { if err != nil {
t.Fatalf("Finalize() failed: %v", err) t.Fatalf("Finalize() failed: %v", err)
} }
@ -212,3 +212,60 @@ func TestAuthorityBuilderMultiple(t *testing.T) {
t.Errorf("GetKey(key).err = %v, want %v", err, ErrNoSuchKey) t.Errorf("GetKey(key).err = %v, want %v", err, ErrNoSuchKey)
} }
} }
func TestAuthorityBuilderCheckpointsAfterXUpdates(t *testing.T) {
pub, priv := testingKey25519(t, 1)
key := Key{Kind: Key25519, Public: pub, Votes: 2}
storage := &Mem{}
a, _, err := Create(storage, State{
Keys: []Key{key},
DisablementSecrets: [][]byte{DisablementKDF([]byte{1, 2, 3})},
}, signer25519(priv))
if err != nil {
t.Fatalf("Create() failed: %v", err)
}
for i := 0; i <= checkpointEvery; i++ {
pub2, _ := testingKey25519(t, int64(i+2))
key2 := Key{Kind: Key25519, Public: pub2, Votes: 1}
b := a.NewUpdater(signer25519(priv))
if err := b.AddKey(key2); err != nil {
t.Fatalf("AddKey(%v) failed: %v", key2, err)
}
updates, err := b.Finalize(storage)
if err != nil {
t.Fatalf("Finalize() failed: %v", err)
}
// See if the update is valid by applying it to the authority
// + checking if the new key is there.
if err := a.Inform(storage, updates); err != nil {
t.Fatalf("could not apply generated updates: %v", err)
}
if _, err := a.state.GetKey(key2.ID()); err != nil {
t.Fatal(err)
}
wantKind := AUMAddKey
if i == checkpointEvery-1 { // Genesis + 49 updates == 50 (the value of checkpointEvery)
wantKind = AUMCheckpoint
}
lastAUM, err := storage.AUM(a.Head())
if err != nil {
t.Fatal(err)
}
if lastAUM.MessageKind != wantKind {
t.Errorf("[%d] HeadAUM.MessageKind = %v, want %v", i, lastAUM.MessageKind, wantKind)
}
}
// Try starting an authority just based on storage.
a2, err := Open(storage)
if err != nil {
t.Fatalf("Failed to open from stored AUMs: %v", err)
}
if a.Head() != a2.Head() {
t.Errorf("stored and computed HEAD differ: got %v, want %v", a2.Head(), a.Head())
}
}

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@ -10,6 +10,7 @@ import (
"errors" "errors"
"fmt" "fmt"
"os" "os"
"reflect"
"sort" "sort"
"github.com/fxamacker/cbor/v2" "github.com/fxamacker/cbor/v2"
@ -181,6 +182,18 @@ func advanceByPrimary(state State, candidates []AUM) (next *AUM, out State, err
} }
aum := pickNextAUM(state, candidates) aum := pickNextAUM(state, candidates)
// TODO(tom): Remove this before GA, this is just a correctness check during implementation.
// Post-GA, we want clients to not error if they dont recognize additional fields in State.
if aum.MessageKind == AUMCheckpoint {
dupe := state
dupe.LastAUMHash = nil
// aum.State is non-nil (see aum.StaticValidate).
if !reflect.DeepEqual(dupe, *aum.State) {
return nil, State{}, errors.New("checkpoint includes changes not represented in earlier AUMs")
}
}
if state, err = state.applyVerifiedAUM(aum); err != nil { if state, err = state.applyVerifiedAUM(aum); err != nil {
return nil, State{}, fmt.Errorf("advancing state: %v", err) return nil, State{}, fmt.Errorf("advancing state: %v", err)
} }
@ -244,10 +257,6 @@ func fastForward(storage Chonk, maxIter int, startState State, done func(curAUM
// computeStateAt returns the State at wantHash. // computeStateAt returns the State at wantHash.
func computeStateAt(storage Chonk, maxIter int, wantHash AUMHash) (State, error) { func computeStateAt(storage Chonk, maxIter int, wantHash AUMHash) (State, error) {
// TODO(tom): This is going to get expensive for really long
// chains. We should make nodes emit a checkpoint every
// X updates or something.
topAUM, err := storage.AUM(wantHash) topAUM, err := storage.AUM(wantHash)
if err != nil { if err != nil {
return State{}, err return State{}, err