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evidence: structs can independently form abci evidence (#5610)

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This commit is contained in:
Callum Waters
2020-11-04 17:14:48 +01:00
committed by GitHub
parent 83c7bd17bf
commit 3922dde05d
36 changed files with 1530 additions and 1915 deletions
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54
light/detector.go
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@@ -78,21 +78,10 @@ func (c *Client) detectDivergence(ctx context.Context, primaryTrace []*types.Lig
witnessesToRemove = append(witnessesToRemove, e.WitnessIndex)
continue
}
// if this is an equivocation or amnesia attack, i.e. the validator sets are the same, then we
// return the height of the conflicting block else if it is a lunatic attack and the validator sets
// are not the same then we send the height of the common header.
commonHeight := primaryBlock.Height
if isInvalidHeader(witnessTrace[len(witnessTrace)-1].Header, primaryBlock.Header) {
// height of the common header
commonHeight = witnessTrace[0].Height
}
// We are suspecting that the primary is faulty, hence we hold the witness as the source of truth
// and generate evidence against the primary that we can send to the witness
primaryEv := &types.LightClientAttackEvidence{
ConflictingBlock: primaryBlock,
CommonHeight: commonHeight, // the first block in the bisection is common to both providers
}
primaryEv := newLightClientAttackEvidence(primaryBlock, witnessTrace[len(witnessTrace)-1], witnessTrace[0])
c.logger.Error("Attempted attack detected. Sending evidence againt primary by witness", "ev", primaryEv,
"primary", c.primary, "witness", supportingWitness)
c.sendEvidence(ctx, primaryEv, supportingWitness)
@@ -117,20 +106,9 @@ func (c *Client) detectDivergence(ctx context.Context, primaryTrace []*types.Lig
c.logger.Info("Error validating primary's divergent header", "primary", c.primary, "err", err)
return ErrLightClientAttack
}
// if this is an equivocation or amnesia attack, i.e. the validator sets are the same, then we
// return the height of the conflicting block else if it is a lunatic attack and the validator sets
// are not the same then we send the height of the common header.
commonHeight = primaryBlock.Height
if isInvalidHeader(primaryTrace[len(primaryTrace)-1].Header, witnessBlock.Header) {
// height of the common header
commonHeight = primaryTrace[0].Height
}
// We now use the primary trace to create evidence against the witness and send it to the primary
witnessEv := &types.LightClientAttackEvidence{
ConflictingBlock: witnessBlock,
CommonHeight: commonHeight, // the first block in the bisection is common to both providers
}
witnessEv := newLightClientAttackEvidence(witnessBlock, primaryTrace[len(primaryTrace)-1], primaryTrace[0])
c.logger.Error("Sending evidence against witness by primary", "ev", witnessEv,
"primary", c.primary, "witness", supportingWitness)
c.sendEvidence(ctx, witnessEv, c.primary)
@@ -251,14 +229,22 @@ func (c *Client) examineConflictingHeaderAgainstTrace(
}
// isInvalidHeader takes a trusted header and matches it againt a conflicting header
// to determine whether the conflicting header was the product of a valid state transition
// or not. If it is then all the deterministic fields of the header should be the same.
// If not, it is an invalid header and constitutes a lunatic attack.
func isInvalidHeader(trusted, conflicting *types.Header) bool {
return !bytes.Equal(trusted.ValidatorsHash, conflicting.ValidatorsHash) ||
!bytes.Equal(trusted.NextValidatorsHash, conflicting.NextValidatorsHash) ||
!bytes.Equal(trusted.ConsensusHash, conflicting.ConsensusHash) ||
!bytes.Equal(trusted.AppHash, conflicting.AppHash) ||
!bytes.Equal(trusted.LastResultsHash, conflicting.LastResultsHash)
// newLightClientAttackEvidence determines the type of attack and then forms the evidence filling out
// all the fields such that it is ready to be sent to a full node.
func newLightClientAttackEvidence(conflicted, trusted, common *types.LightBlock) *types.LightClientAttackEvidence {
ev := &types.LightClientAttackEvidence{ConflictingBlock: conflicted}
// if this is an equivocation or amnesia attack, i.e. the validator sets are the same, then we
// return the height of the conflicting block else if it is a lunatic attack and the validator sets
// are not the same then we send the height of the common header.
if ev.ConflictingHeaderIsInvalid(trusted.Header) {
ev.CommonHeight = common.Height
ev.Timestamp = common.Time
ev.TotalVotingPower = common.ValidatorSet.TotalVotingPower()
} else {
ev.CommonHeight = trusted.Height
ev.Timestamp = trusted.Time
ev.TotalVotingPower = trusted.ValidatorSet.TotalVotingPower()
}
ev.ByzantineValidators = ev.GetByzantineValidators(common.ValidatorSet, trusted.SignedHeader)
return ev
}