move proxyApp.VerifyFraudProofSync to ProofService (cosmos#1000)

Fixes cosmos#982

---------

Co-authored-by: Ganesha Upadhyaya <gupadhyaya@Ganeshas-MacBook-Pro-2.local>

Author: gupadhyaya

block/manager.go

@@ -258,42 +258,30 @@ func (m *Manager) ProcessFraudProof(ctx context.Context, cancel context.CancelFu
 	}
 	defer sub.Cancel()
 
-	// continuously process the fraud proofs received via subscription
-	for {
-		// sub.Proof is a blocking call that only returns on proof received or context ended
-		proof, err := sub.Proof(ctx)
-		if err != nil {
-			m.logger.Error("failed to receive gossiped fraud proof", "error", err)
-			return
-		}
+	// blocks until a valid fraud proof is received via subscription
+	// sub.Proof is a blocking call that only returns on proof received or context ended
+	proof, err := sub.Proof(ctx)
+	if err != nil {
+		m.logger.Error("failed to receive gossiped fraud proof", "error", err)
+		return
+	}
 
-		// only handle the state fraud proofs for now
-		fraudProof, ok := proof.(*types.StateFraudProof)
-		if !ok {
-			m.logger.Error("unexpected type received for state fraud proof", "error", err)
-			return
-		}
-		m.logger.Debug("fraud proof received",
-			"block height", fraudProof.BlockHeight,
-			"pre-state app hash", fraudProof.PreStateAppHash,
-			"expected valid app hash", fraudProof.ExpectedValidAppHash,
-			"length of state witness", len(fraudProof.StateWitness),
-		)
-		// TODO(light-client): Set up a new cosmos-sdk app
-		// TODO: Add fraud proof window validation
-
-		success, err := m.executor.VerifyFraudProof(&fraudProof.FraudProof, fraudProof.ExpectedValidAppHash)
-		if err != nil {
-			m.logger.Error("failed to verify fraud proof", "error", err)
-			continue
-		}
-		if success {
-			// halt chain
-			m.logger.Info("verified fraud proof, halting chain")
-			cancel()
-			return
-		}
+	// only handle the state fraud proofs for now
+	fraudProof, ok := proof.(*types.StateFraudProof)
+	if !ok {
+		m.logger.Error("unexpected type received for state fraud proof", "error", err)
+		return
 	}
+	m.logger.Debug("fraud proof received",
+		"block height", fraudProof.BlockHeight,
+		"pre-state app hash", fraudProof.PreStateAppHash,
+		"expected valid app hash", fraudProof.ExpectedValidAppHash,
+		"length of state witness", len(fraudProof.StateWitness),
+	)
+
+	// halt chain
+	m.logger.Info("verified fraud proof, halting chain")
+	cancel()
 }
 
 // SyncLoop is responsible for syncing blocks.

node/full.go

@@ -34,6 +34,7 @@ import (
 	"github.com/rollkit/rollkit/state/txindex"
 	"github.com/rollkit/rollkit/state/txindex/kv"
 	"github.com/rollkit/rollkit/store"
+	"github.com/rollkit/rollkit/types"
 )
 
 // prefixes used in KV store to separate main node data from DALC data
@@ -298,6 +299,9 @@ func (n *FullNode) OnStart() error {
 	// since p2p pubsub and host are required to create ProofService,
 	// we have to delay the construction until Start and use the help of ProofServiceFactory
 	n.fraudService = n.proofServiceFactory.CreateProofService()
+	if err := n.fraudService.AddVerifier(types.StateFraudProofType, VerifierFn(n.proxyApp)); err != nil {
+		return fmt.Errorf("error while registering verifier for fraud service: %w", err)
+	}
 	if err = n.fraudService.Start(n.ctx); err != nil {
 		return fmt.Errorf("error while starting fraud exchange service: %w", err)
 	}

node/light.go

@@ -118,6 +118,9 @@ func (ln *LightNode) OnStart() error {
 	}
 
 	ln.fraudService = ln.proofServiceFactory.CreateProofService()
+	if err := ln.fraudService.AddVerifier(types.StateFraudProofType, VerifierFn(ln.proxyApp)); err != nil {
+		return fmt.Errorf("error while registering verifier for fraud service: %w", err)
+	}
 	if err := ln.fraudService.Start(ln.ctx); err != nil {
 		return fmt.Errorf("error while starting fraud exchange service: %w", err)
 	}

node/proof_service_factory.go

@@ -1,13 +1,37 @@
 package node
 
 import (
+	"errors"
+
 	"github.com/celestiaorg/go-fraud"
 	"github.com/celestiaorg/go-fraud/fraudserv"
 	"github.com/ipfs/go-datastore"
+	abci "github.com/tendermint/tendermint/abci/types"
+	proxy "github.com/tendermint/tendermint/proxy"
 
 	"github.com/rollkit/rollkit/p2p"
+	"github.com/rollkit/rollkit/types"
 )
 
+var VerifierFn = func(proxyApp proxy.AppConns) func(fraudProof fraud.Proof) (bool, error) {
+	return func(fraudProof fraud.Proof) (bool, error) {
+		stateFraudProof, ok := fraudProof.(*types.StateFraudProof)
+		if !ok {
+			return false, errors.New("unknown fraud proof")
+		}
+		resp, err := proxyApp.Consensus().VerifyFraudProofSync(
+			abci.RequestVerifyFraudProof{
+				FraudProof:           &stateFraudProof.FraudProof,
+				ExpectedValidAppHash: stateFraudProof.ExpectedValidAppHash,
+			},
+		)
+		if err != nil {
+			return false, err
+		}
+		return resp.Success, nil
+	}
+}
+
 type ProofServiceFactory struct {
 	client        *p2p.Client
 	getter        fraud.HeaderFetcher