prysm-pulse/beacon-chain/forkchoice/protoarray/proposer_boost_test.go
Potuz 237807b248
Do not update forkchoice checkpoints on calls to Head (#10702)
* Only update forkchoice checkpoints at epoch transition

* gazelle

* blockchain package changes

* fix node

* spectest package

* rpc package

* fix spec test

* Fix spectests

* fix new_slot.test

* gaz

* fix spectests

* fix conflicts

* Update beacon-chain/blockchain/process_block.go

* regression do not update on newSlot

* revert bd64cab

* terence's review

* fix conflicts

* fix latest conflicts

* gaz

* go mod tidy

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>
2022-05-22 18:37:01 +00:00

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package protoarray
import (
"context"
"testing"
"time"
forkchoicetypes "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/types"
"github.com/prysmaticlabs/prysm/config/params"
types "github.com/prysmaticlabs/prysm/consensus-types/primitives"
"github.com/prysmaticlabs/prysm/testing/assert"
"github.com/prysmaticlabs/prysm/testing/require"
)
// Simple, ex-ante attack mitigation using proposer boost.
// In a nutshell, an adversarial block proposer in slot n+1 keeps its proposal hidden.
// The honest block proposer in slot n+2 will then propose an honest block. The
// adversary can now use its committee members votes from both slots n+1 and n+2.
// and release their withheld block of slot n+2 in an attempt to win fork choice.
// If the honest proposal is boosted at slot n+2, it will win against this attacker.
func TestForkChoice_BoostProposerRoot_PreventsExAnteAttack(t *testing.T) {
ctx := context.Background()
jEpoch, fEpoch := types.Epoch(0), types.Epoch(0)
zeroHash := params.BeaconConfig().ZeroHash
balances := make([]uint64, 64) // 64 active validators.
for i := 0; i < len(balances); i++ {
balances[i] = 10
}
t.Run("nil args check", func(t *testing.T) {
f := setup(jEpoch, fEpoch)
err := f.BoostProposerRoot(ctx, nil)
require.ErrorContains(t, "nil function args", err)
})
t.Run("back-propagates boost score to ancestors after proposer boosting", func(t *testing.T) {
f := setup(jEpoch, fEpoch)
// The head should always start at the finalized block.
headRoot, err := f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, zeroHash, headRoot, "Incorrect head with genesis")
// Insert block at slot 1 into the tree and verify head is at that block:
// 0
// |
// 1 <- HEAD
slot := types.Slot(1)
newRoot := indexToHash(1)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
slot,
newRoot,
headRoot,
zeroHash,
jEpoch,
fEpoch,
),
)
f.ProcessAttestation(ctx, []uint64{0}, newRoot, fEpoch)
headRoot, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 1")
// Insert block at slot 2 into the tree and verify head is at that block:
// 0
// |
// 1
// |
// 2 <- HEAD
slot = types.Slot(2)
newRoot = indexToHash(2)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
slot,
newRoot,
headRoot,
zeroHash,
jEpoch,
fEpoch,
),
)
f.ProcessAttestation(ctx, []uint64{1}, newRoot, fEpoch)
headRoot, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 2")
// Insert block at slot 3 into the tree and verify head is at that block:
// 0
// |
// 1
// |
// 2
// |
// 3 <- HEAD
slot = types.Slot(3)
newRoot = indexToHash(3)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
slot,
newRoot,
headRoot,
zeroHash,
jEpoch,
fEpoch,
),
)
f.ProcessAttestation(ctx, []uint64{2}, newRoot, fEpoch)
headRoot, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 3")
// Insert a second block at slot 4 into the tree and boost its score.
// 0
// |
// 1
// |
// 2
// / \
// 3 |
// 4 <- HEAD
slot = types.Slot(4)
newRoot = indexToHash(4)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
slot,
newRoot,
indexToHash(2),
zeroHash,
jEpoch,
fEpoch,
),
)
f.ProcessAttestation(ctx, []uint64{3}, newRoot, fEpoch)
clockSlot := types.Slot(4)
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: newRoot,
BlockSlot: slot,
CurrentSlot: clockSlot,
SecondsIntoSlot: 0,
}
require.NoError(t, f.BoostProposerRoot(ctx, args))
headRoot, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, newRoot, headRoot, "Incorrect head for justified epoch at slot 3")
// Check the ancestor scores from the store.
require.Equal(t, 5, len(f.store.nodes))
// Expect nodes to have a boosted, back-propagated score.
// Ancestors have the added weights of their children. Genesis is a special exception at 0 weight,
require.Equal(t, f.store.nodes[0].weight, uint64(0))
// Otherwise, assuming a block, A, that is not-genesis:
//
// A -> B -> C
//
//Where each one has a weight of 10 individually, the final weights will look like
//
// (A: 30) -> (B: 20) -> (C: 10)
//
// The boost adds 14 to the weight, so if C is boosted, we would have
//
// (A: 44) -> (B: 34) -> (C: 24)
//
// In this case, we have a small fork:
//
// (A: 54) -> (B: 44) -> (C: 10)
// \_->(D: 24)
//
// So B has its own weight, 10, and the sum of both C and D. That's why we see weight 54 in the
// middle instead of the normal progression of (54 -> 44 -> 24).
require.Equal(t, f.store.nodes[1].weight, uint64(54))
require.Equal(t, f.store.nodes[2].weight, uint64(44))
require.Equal(t, f.store.nodes[3].weight, uint64(10))
require.Equal(t, f.store.nodes[4].weight, uint64(24))
// Regression: process attestations for C, check that it
// becomes head, we need two attestations to have C.weight = 30 > 24 = D.weight
f.ProcessAttestation(ctx, []uint64{4, 5}, indexToHash(3), fEpoch)
headRoot, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, indexToHash(3), headRoot, "Incorrect head for justified epoch at slot 4")
})
t.Run("vanilla ex ante attack", func(t *testing.T) {
f := setup(jEpoch, fEpoch)
// The head should always start at the finalized block.
r, err := f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, zeroHash, r, "Incorrect head with genesis")
// Proposer from slot 1 does not reveal their block, B, at slot 1.
// Proposer at slot 2 does reveal their block, C, and it becomes the head.
// C builds on A, as proposer at slot 1 did not reveal B.
// A
// / \
// (B?) \
// \
// C <- Slot 2 HEAD
honestBlockSlot := types.Slot(2)
honestBlock := indexToHash(2)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
honestBlockSlot,
honestBlock,
zeroHash,
zeroHash,
jEpoch,
fEpoch,
),
)
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
maliciouslyWithheldBlockSlot := types.Slot(1)
maliciouslyWithheldBlock := indexToHash(1)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
maliciouslyWithheldBlockSlot,
maliciouslyWithheldBlock,
zeroHash,
zeroHash,
jEpoch,
fEpoch,
),
)
// Ensure the head is C, the honest block.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
// We boost the honest proposal at slot 2.
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: honestBlock,
BlockSlot: honestBlockSlot,
CurrentSlot: types.Slot(2),
SecondsIntoSlot: 0,
}
require.NoError(t, f.BoostProposerRoot(ctx, args))
// The maliciously withheld block has one vote.
votes := []uint64{1}
f.ProcessAttestation(ctx, votes, maliciouslyWithheldBlock, fEpoch)
// Ensure the head is STILL C, the honest block, as the honest block had proposer boost.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
})
t.Run("adversarial attestations > proposer boosting", func(t *testing.T) {
f := setup(jEpoch, fEpoch)
// The head should always start at the finalized block.
r, err := f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, zeroHash, r, "Incorrect head with genesis")
// Proposer from slot 1 does not reveal their block, B, at slot 1.
// Proposer at slot 2 does reveal their block, C, and it becomes the head.
// C builds on A, as proposer at slot 1 did not reveal B.
// A
// / \
// (B?) \
// \
// C <- Slot 2 HEAD
honestBlockSlot := types.Slot(2)
honestBlock := indexToHash(2)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
honestBlockSlot,
honestBlock,
zeroHash,
zeroHash,
jEpoch,
fEpoch,
),
)
// Ensure C is the head.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
maliciouslyWithheldBlockSlot := types.Slot(1)
maliciouslyWithheldBlock := indexToHash(1)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
maliciouslyWithheldBlockSlot,
maliciouslyWithheldBlock,
zeroHash,
zeroHash,
jEpoch,
fEpoch,
),
)
// Ensure C is still the head after the malicious proposer reveals their block.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, honestBlock, r, "Incorrect head for justified epoch at slot 2")
// We boost the honest proposal at slot 2.
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: honestBlock,
BlockSlot: honestBlockSlot,
CurrentSlot: types.Slot(2),
SecondsIntoSlot: 0,
}
require.NoError(t, f.BoostProposerRoot(ctx, args))
// An attestation is received for B that has more voting power than C with the proposer boost,
// allowing B to then become the head if their attestation has enough adversarial votes.
votes := []uint64{1, 2}
f.ProcessAttestation(ctx, votes, maliciouslyWithheldBlock, fEpoch)
// Expect the head to have switched to B.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, maliciouslyWithheldBlock, r, "Expected B to become the head")
})
t.Run("boosting necessary to sandwich attack", func(t *testing.T) {
// Boosting necessary to sandwich attack.
// Objects:
// Block A - slot N
// Block B (parent A) - slot N+1
// Block C (parent A) - slot N+2
// Block D (parent B) - slot N+3
// Attestation_1 (Block C); size 1 - slot N+2 (honest)
// Steps:
// Block A received at N — A is head
// Block C received at N+2 — C is head
// Block B received at N+2 — C is head
// Attestation_1 received at N+3 — C is head
// Block D received at N+3 — D is head
f := setup(jEpoch, fEpoch)
a := zeroHash
// The head should always start at the finalized block.
r, err := f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, zeroHash, r, "Incorrect head with genesis")
cSlot := types.Slot(2)
c := indexToHash(2)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
cSlot,
c,
a, // parent
zeroHash,
jEpoch,
fEpoch,
),
)
// Ensure C is the head.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, c, r, "Incorrect head for justified epoch at slot 2")
// We boost C.
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: c,
BlockSlot: cSlot,
CurrentSlot: types.Slot(2),
SecondsIntoSlot: 0,
}
require.NoError(t, f.BoostProposerRoot(ctx, args))
bSlot := types.Slot(1)
b := indexToHash(1)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
bSlot,
b,
a, // parent
zeroHash,
jEpoch,
fEpoch,
),
)
// Ensure C is still the head.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, c, r, "Incorrect head for justified epoch at slot 2")
// An attestation for C is received at slot N+3.
votes := []uint64{1}
f.ProcessAttestation(ctx, votes, c, fEpoch)
// A block D, building on B, is received at slot N+3. It should not be able to win without boosting.
dSlot := types.Slot(3)
d := indexToHash(3)
require.NoError(t,
f.InsertOptimisticBlock(
ctx,
dSlot,
d,
b, // parent
zeroHash,
jEpoch,
fEpoch,
),
)
// D cannot win without a boost.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, c, r, "Expected C to remain the head")
// Block D receives the boost.
args = &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: d,
BlockSlot: dSlot,
CurrentSlot: types.Slot(3),
SecondsIntoSlot: 0,
}
require.NoError(t, f.BoostProposerRoot(ctx, args))
// Ensure D becomes the head thanks to boosting.
r, err = f.Head(ctx, zeroHash, balances)
require.NoError(t, err)
assert.Equal(t, d, r, "Expected D to become the head")
})
}
func TestForkChoice_BoostProposerRoot(t *testing.T) {
params.SetupTestConfigCleanup(t)
cfg := params.BeaconConfig()
cfg.SecondsPerSlot = 6
cfg.IntervalsPerSlot = 3
params.OverrideBeaconConfig(cfg)
ctx := context.Background()
t.Run("does not boost block from different slot", func(t *testing.T) {
f := &ForkChoice{
store: &Store{},
}
blockRoot := [32]byte{'A'}
// Trying to boost a block from slot 0 should not work.
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: blockRoot,
BlockSlot: types.Slot(0),
CurrentSlot: types.Slot(1),
SecondsIntoSlot: 0,
}
err := f.BoostProposerRoot(ctx, args)
require.NoError(t, err)
require.DeepEqual(t, [32]byte{}, f.store.proposerBoostRoot)
})
t.Run("does not boost untimely block from same slot", func(t *testing.T) {
f := &ForkChoice{
store: &Store{},
}
// Genesis set to 1 slot ago + X where X > attesting interval.
attestingInterval := time.Duration(cfg.SecondsPerSlot/cfg.IntervalsPerSlot) * time.Second
greaterThanAttestingInterval := attestingInterval + time.Second
// Trying to boost a block from slot 1 that is untimely should not work.
blockRoot := [32]byte{'A'}
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: blockRoot,
BlockSlot: types.Slot(1),
CurrentSlot: 1,
SecondsIntoSlot: uint64(greaterThanAttestingInterval.Seconds()),
}
err := f.BoostProposerRoot(ctx, args)
require.NoError(t, err)
require.DeepEqual(t, [32]byte{}, f.store.proposerBoostRoot)
})
t.Run("boosts perfectly timely block from same slot", func(t *testing.T) {
f := &ForkChoice{
store: &Store{},
}
// Genesis set to 1 slot ago + 0 seconds into the attesting interval.
blockRoot := [32]byte{'A'}
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: blockRoot,
BlockSlot: types.Slot(1),
CurrentSlot: types.Slot(1),
SecondsIntoSlot: 0,
}
err := f.BoostProposerRoot(ctx, args)
require.NoError(t, err)
require.DeepEqual(t, [32]byte{'A'}, f.store.proposerBoostRoot)
})
t.Run("boosts timely block from same slot", func(t *testing.T) {
f := &ForkChoice{
store: &Store{},
}
blockRoot := [32]byte{'A'}
halfAttestingInterval := time.Second
args := &forkchoicetypes.ProposerBoostRootArgs{
BlockRoot: blockRoot,
BlockSlot: types.Slot(1),
CurrentSlot: types.Slot(1),
SecondsIntoSlot: uint64(halfAttestingInterval.Seconds()),
}
err := f.BoostProposerRoot(ctx, args)
require.NoError(t, err)
require.DeepEqual(t, [32]byte{'A'}, f.store.proposerBoostRoot)
})
}
func TestForkChoice_computeProposerBoostScore(t *testing.T) {
t.Run("nil justified balances throws error", func(t *testing.T) {
_, err := computeProposerBoostScore(nil)
require.ErrorContains(t, "no active validators", err)
})
t.Run("normal active balances computes score", func(t *testing.T) {
validatorBalances := make([]uint64, 64) // Num validators
for i := 0; i < len(validatorBalances); i++ {
validatorBalances[i] = 10
}
// Avg balance is 10, and the number of validators is 64.
// With a committee size of num validators (64) / slots per epoch (32) == 2.
// we then have a committee weight of avg balance * committee size = 10 * 2 = 20.
// The score then becomes 10 * PROPOSER_SCORE_BOOST // 100, which is
// 20 * 70 / 100 = 14.
score, err := computeProposerBoostScore(validatorBalances)
require.NoError(t, err)
require.Equal(t, uint64(14), score)
})
}