evidence: modularise evidence by moving verification function into evidence package (#5234)

state/validation.go

@@ -144,50 +144,23 @@ func validateBlock(evidencePool EvidencePool, stateDB dbm.DB, state State, block
 			block.Height, state.InitialHeight)
 	}
 
-	// Limit the amount of evidence
-	numEvidence := len(block.Evidence.Evidence)
-	// MaxNumEvidence is capped at uint16, so conversion is always safe.
-	if maxEvidence := int(state.ConsensusParams.Evidence.MaxNum); numEvidence > maxEvidence {
-		return types.NewErrEvidenceOverflow(maxEvidence, numEvidence)
+	// Check evidence doesn't exceed the limit. MaxNumEvidence is capped at uint16, so conversion is always safe.
+	if max, got := int(state.ConsensusParams.Evidence.MaxNum), len(block.Evidence.Evidence); got > max {
+		return types.NewErrEvidenceOverflow(max, got)
 	}
 
 	// Validate all evidence.
 	for idx, ev := range block.Evidence.Evidence {
-		// check that no evidence has been submitted more than once
+		// Check that no evidence has been submitted more than once
 		for i := idx + 1; i < len(block.Evidence.Evidence); i++ {
 			if ev.Equal(block.Evidence.Evidence[i]) {
 				return types.NewErrEvidenceInvalid(ev, errors.New("evidence was submitted twice"))
 			}
 		}
-		if evidencePool != nil {
-			if evidencePool.IsCommitted(ev) {
-				return types.NewErrEvidenceInvalid(ev, errors.New("evidence was already committed"))
-			}
-			if evidencePool.IsPending(ev) {
-				continue
-			}
-		}
-		// if we don't already have amnesia evidence we need to add it to start our own trial period unless
-		// a) a valid polc has already been attached
-		// b) the accused node voted back on an earlier round
-		if ae, ok := ev.(*types.AmnesiaEvidence); ok && ae.Polc.IsAbsent() && ae.PotentialAmnesiaEvidence.VoteA.Round <
-			ae.PotentialAmnesiaEvidence.VoteB.Round {
-			if err := evidencePool.AddEvidence(ae.PotentialAmnesiaEvidence); err != nil {
-				return types.NewErrEvidenceInvalid(ev,
-					fmt.Errorf("unknown amnesia evidence, trying to add to evidence pool, err: %w", err))
-			}
-			return types.NewErrEvidenceInvalid(ev, errors.New("amnesia evidence is new and hasn't undergone trial period yet"))
-		}
 
-		// A header needs to be fetched. For lunatic evidence this is so we can verify
-		// that some of the fields are different to the ones we have. For all evidence it
-		// it so we can verify that the time of the evidence is correct
-		header := evidencePool.Header(ev.Height())
-		if header == nil {
-			return fmt.Errorf("don't have block meta at height #%d", ev.Height())
-		}
-
-		if err := VerifyEvidence(stateDB, state, ev, header); err != nil {
+		// Verify evidence using the evidence pool
+		err := evidencePool.Verify(ev)
+		if err != nil {
 			return types.NewErrEvidenceInvalid(ev, err)
 		}
 
@@ -195,73 +168,3 @@ func validateBlock(evidencePool EvidencePool, stateDB dbm.DB, state State, block
 
 	return nil
 }
-
-// VerifyEvidence verifies the evidence fully by checking:
-// - it is sufficiently recent (MaxAge)
-// - it is from a key who was a validator at the given height
-// - it is internally consistent
-// - it was properly signed by the alleged equivocator
-func VerifyEvidence(stateDB dbm.DB, state State, evidence types.Evidence, committedHeader *types.Header) error {
-	var (
-		height         = state.LastBlockHeight
-		evidenceParams = state.ConsensusParams.Evidence
-
-		ageDuration  = state.LastBlockTime.Sub(evidence.Time())
-		ageNumBlocks = height - evidence.Height()
-	)
-
-	if committedHeader.Time != evidence.Time() {
-		return fmt.Errorf("evidence time (%v) is different to the time of the header we have for the same height (%v)",
-			evidence.Time(),
-			committedHeader.Time,
-		)
-	}
-
-	if ageDuration > evidenceParams.MaxAgeDuration && ageNumBlocks > evidenceParams.MaxAgeNumBlocks {
-		return fmt.Errorf(
-			"evidence from height %d (created at: %v) is too old; min height is %d and evidence can not be older than %v",
-			evidence.Height(),
-			evidence.Time(),
-			height-evidenceParams.MaxAgeNumBlocks,
-			state.LastBlockTime.Add(evidenceParams.MaxAgeDuration),
-		)
-	}
-	if ev, ok := evidence.(*types.LunaticValidatorEvidence); ok {
-		if err := ev.VerifyHeader(committedHeader); err != nil {
-			return err
-		}
-	}
-
-	valset, err := LoadValidators(stateDB, evidence.Height())
-	if err != nil {
-		// TODO: if err is just that we cant find it cuz we pruned, ignore.
-		// TODO: if its actually bad evidence, punish peer
-		return err
-	}
-
-	addr := evidence.Address()
-	var val *types.Validator
-
-	if ae, ok := evidence.(*types.AmnesiaEvidence); ok {
-		// check the validator set against the polc to make sure that a majority of valid votes was reached
-		if !ae.Polc.IsAbsent() {
-			err = ae.Polc.ValidateVotes(valset, state.ChainID)
-			if err != nil {
-				return fmt.Errorf("amnesia evidence contains invalid polc, err: %w", err)
-			}
-		}
-	}
-
-	// For all other types, expect evidence.Address to be a validator at height
-	// evidence.Height.
-	_, val = valset.GetByAddress(addr)
-	if val == nil {
-		return fmt.Errorf("address %X was not a validator at height %d", addr, evidence.Height())
-	}
-
-	if err := evidence.Verify(state.ChainID, val.PubKey); err != nil {
-		return err
-	}
-
-	return nil
-}