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tka: implement API surface for generating updates

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Based on the builder pattern.

Signed-off-by: Tom DNetto <tom@tailscale.com>
pull/5228/head
Tom DNetto 2 years ago committed by Tom
parent acc3b7f259
commit 5e61d52f91
2 changed files with 321 additions and 0 deletions
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111
tka/builder.go
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// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tka
import (
"fmt"
)
// UpdateBuilder implements a builder for changes to the tailnet
// key authority.
//
// Finalize must be called to compute the update messages, which
// must then be applied to all Authority objects using Inform().
type UpdateBuilder struct {
a *Authority
signer func(*AUM) error
state State
parent AUMHash
out []AUM
}
func (b *UpdateBuilder) mkUpdate(update AUM) error {
prevHash := make([]byte, len(b.parent))
copy(prevHash, b.parent[:])
update.PrevAUMHash = prevHash
if b.signer != nil {
if err := b.signer(&update); err != nil {
return fmt.Errorf("signing failed: %v", err)
}
}
if err := update.StaticValidate(); err != nil {
return fmt.Errorf("generated update was invalid: %v", err)
}
state, err := b.state.applyVerifiedAUM(update)
if err != nil {
return fmt.Errorf("update cannot be applied: %v", err)
}
b.state = state
b.parent = update.Hash()
b.out = append(b.out, update)
return nil
}
// AddKey adds a new key to the authority.
func (b *UpdateBuilder) AddKey(key Key) error {
if _, err := b.state.GetKey(key.ID()); err == nil {
return fmt.Errorf("cannot add key %v: already exists", key)
}
return b.mkUpdate(AUM{MessageKind: AUMAddKey, Key: &key})
}
// RemoveKey removes a key from the authority.
func (b *UpdateBuilder) RemoveKey(keyID KeyID) error {
if _, err := b.state.GetKey(keyID); err != nil {
return fmt.Errorf("failed reading key %x: %v", keyID, err)
}
return b.mkUpdate(AUM{MessageKind: AUMRemoveKey, KeyID: keyID})
}
// SetKeyVote updates the number of votes of an existing key.
func (b *UpdateBuilder) SetKeyVote(keyID KeyID, votes uint) error {
if _, err := b.state.GetKey(keyID); err != nil {
return fmt.Errorf("failed reading key %x: %v", keyID, err)
}
return b.mkUpdate(AUM{MessageKind: AUMUpdateKey, Votes: &votes, KeyID: keyID})
}
// SetKeyMeta updates key-value metadata stored against an existing key.
//
// TODO(tom): Provide an API to update specific values rather than the whole
// map.
func (b *UpdateBuilder) SetKeyMeta(keyID KeyID, meta map[string]string) error {
if _, err := b.state.GetKey(keyID); err != nil {
return fmt.Errorf("failed reading key %x: %v", keyID, err)
}
return b.mkUpdate(AUM{MessageKind: AUMUpdateKey, Meta: meta, KeyID: keyID})
}
// Finalize returns the set of update message to actuate the update.
func (b *UpdateBuilder) Finalize() ([]AUM, error) {
if len(b.out) > 0 {
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 b.out, nil
}
// NewUpdater returns a builder you can use to make changes to
// the tailnet key authority.
//
// The provided signer function, if non-nil, is called with each update
// to compute and apply signatures.
//
// Updates are specified by calling methods on the returned UpdatedBuilder.
// Call Finalize() when you are done to obtain the specific update messages
// which actuate the changes.
func (a *Authority) NewUpdater(signer func(*AUM) error) *UpdateBuilder {
return &UpdateBuilder{
a: a,
signer: signer,
parent: a.Head(),
state: a.state,
}
}

210
tka/builder_test.go
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// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tka
import (
"testing"
"github.com/google/go-cmp/cmp"
)
func TestAuthorityBuilderAddKey(t *testing.T) {
pub, priv := testingKey25519(t, 1)
key := Key{Kind: Key25519, Public: pub, Votes: 2}
a, _, err := Create(&Mem{}, State{
Keys: []Key{key},
DisablementSecrets: [][]byte{disablementKDF([]byte{1, 2, 3})},
}, priv)
if err != nil {
t.Fatalf("Create() failed: %v", err)
}
pub2, _ := testingKey25519(t, 2)
key2 := Key{Kind: Key25519, Public: pub2, Votes: 1}
b := a.NewUpdater(func(update *AUM) error {
update.sign25519(priv)
return nil
})
if err := b.AddKey(key2); err != nil {
t.Fatalf("AddKey(%v) failed: %v", key2, err)
}
updates, err := b.Finalize()
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(updates); err != nil {
t.Fatalf("could not apply generated updates: %v", err)
}
if _, err := a.state.GetKey(key2.ID()); err != nil {
t.Errorf("could not read new key: %v", err)
}
}
func TestAuthorityBuilderRemoveKey(t *testing.T) {
pub, priv := testingKey25519(t, 1)
key := Key{Kind: Key25519, Public: pub, Votes: 2}
pub2, _ := testingKey25519(t, 2)
key2 := Key{Kind: Key25519, Public: pub2, Votes: 1}
a, _, err := Create(&Mem{}, State{
Keys: []Key{key, key2},
DisablementSecrets: [][]byte{disablementKDF([]byte{1, 2, 3})},
}, priv)
if err != nil {
t.Fatalf("Create() failed: %v", err)
}
b := a.NewUpdater(func(update *AUM) error {
update.sign25519(priv)
return nil
})
if err := b.RemoveKey(key2.ID()); err != nil {
t.Fatalf("RemoveKey(%v) failed: %v", key2, err)
}
updates, err := b.Finalize()
if err != nil {
t.Fatalf("Finalize() failed: %v", err)
}
// See if the update is valid by applying it to the authority
// + checking if the key has been removed.
if err := a.Inform(updates); err != nil {
t.Fatalf("could not apply generated updates: %v", err)
}
if _, err := a.state.GetKey(key2.ID()); err != ErrNoSuchKey {
t.Errorf("GetKey(key2).err = %v, want %v", err, ErrNoSuchKey)
}
}
func TestAuthorityBuilderSetKeyVote(t *testing.T) {
pub, priv := testingKey25519(t, 1)
key := Key{Kind: Key25519, Public: pub, Votes: 2}
a, _, err := Create(&Mem{}, State{
Keys: []Key{key},
DisablementSecrets: [][]byte{disablementKDF([]byte{1, 2, 3})},
}, priv)
if err != nil {
t.Fatalf("Create() failed: %v", err)
}
b := a.NewUpdater(func(update *AUM) error {
update.sign25519(priv)
return nil
})
if err := b.SetKeyVote(key.ID(), 5); err != nil {
t.Fatalf("SetKeyVote(%v) failed: %v", key.ID(), err)
}
updates, err := b.Finalize()
if err != nil {
t.Fatalf("Finalize() failed: %v", err)
}
// See if the update is valid by applying it to the authority
// + checking if the update is there.
if err := a.Inform(updates); err != nil {
t.Fatalf("could not apply generated updates: %v", err)
}
k, err := a.state.GetKey(key.ID())
if err != nil {
t.Fatal(err)
}
if got, want := k.Votes, uint(5); got != want {
t.Errorf("key.Votes = %d, want %d", got, want)
}
}
func TestAuthorityBuilderSetKeyMeta(t *testing.T) {
pub, priv := testingKey25519(t, 1)
key := Key{Kind: Key25519, Public: pub, Votes: 2, Meta: map[string]string{"a": "b"}}
a, _, err := Create(&Mem{}, State{
Keys: []Key{key},
DisablementSecrets: [][]byte{disablementKDF([]byte{1, 2, 3})},
}, priv)
if err != nil {
t.Fatalf("Create() failed: %v", err)
}
b := a.NewUpdater(func(update *AUM) error {
update.sign25519(priv)
return nil
})
if err := b.SetKeyMeta(key.ID(), map[string]string{"b": "c"}); err != nil {
t.Fatalf("SetKeyMeta(%v) failed: %v", key, err)
}
updates, err := b.Finalize()
if err != nil {
t.Fatalf("Finalize() failed: %v", err)
}
// See if the update is valid by applying it to the authority
// + checking if the update is there.
if err := a.Inform(updates); err != nil {
t.Fatalf("could not apply generated updates: %v", err)
}
k, err := a.state.GetKey(key.ID())
if err != nil {
t.Fatal(err)
}
if diff := cmp.Diff(map[string]string{"b": "c"}, k.Meta); diff != "" {
t.Errorf("updated meta differs (-want, +got):\n%s", diff)
}
}
func TestAuthorityBuilderMultiple(t *testing.T) {
pub, priv := testingKey25519(t, 1)
key := Key{Kind: Key25519, Public: pub, Votes: 2}
a, _, err := Create(&Mem{}, State{
Keys: []Key{key},
DisablementSecrets: [][]byte{disablementKDF([]byte{1, 2, 3})},
}, priv)
if err != nil {
t.Fatalf("Create() failed: %v", err)
}
pub2, _ := testingKey25519(t, 2)
key2 := Key{Kind: Key25519, Public: pub2, Votes: 1}
b := a.NewUpdater(func(update *AUM) error {
update.sign25519(priv)
return nil
})
if err := b.AddKey(key2); err != nil {
t.Fatalf("AddKey(%v) failed: %v", key2, err)
}
if err := b.SetKeyVote(key2.ID(), 42); err != nil {
t.Fatalf("SetKeyVote(%v) failed: %v", key2, err)
}
if err := b.RemoveKey(key.ID()); err != nil {
t.Fatalf("RemoveKey(%v) failed: %v", key, err)
}
updates, err := b.Finalize()
if err != nil {
t.Fatalf("Finalize() failed: %v", err)
}
// See if the update is valid by applying it to the authority
// + checking if the update is there.
if err := a.Inform(updates); err != nil {
t.Fatalf("could not apply generated updates: %v", err)
}
k, err := a.state.GetKey(key2.ID())
if err != nil {
t.Fatal(err)
}
if got, want := k.Votes, uint(42); got != want {
t.Errorf("key.Votes = %d, want %d", got, want)
}
if _, err := a.state.GetKey(key.ID()); err != ErrNoSuchKey {
t.Errorf("GetKey(key).err = %v, want %v", err, ErrNoSuchKey)
}
}
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