Add gossip fraud proof capability over p2p

Author: Manav-Aggarwal

block/manager.go

@@ -59,6 +59,8 @@ type Manager struct {
 	HeaderOutCh chan *types.Header
 	HeaderInCh  chan *types.Header
 
+	FraudProofCh chan *types.FraudProof
+
 	syncTarget uint64
 	blockInCh  chan newBlockEvent
 	syncCache  map[uint64]*types.Block
@@ -230,6 +232,9 @@ func (m *Manager) SyncLoop(ctx context.Context) {
 				}
 				delete(m.syncCache, currentHeight+1)
 			}
+		case fraudProof := <-m.FraudProofCh:
+			m.logger.Debug("fraud proof received", "Block Height", fraudProof.BlockHeight)
+			// TODO(manav): Set up a new cosmos app here
 		case <-ctx.Done():
 			return
 		}

go.mod

@@ -26,6 +26,7 @@ require (
 	go.uber.org/multierr v1.8.0
 	golang.org/x/net v0.0.0-20220520000938-2e3eb7b945c2
 	google.golang.org/grpc v1.46.2
+	google.golang.org/protobuf v1.28.0
 )
 
 require (
@@ -187,7 +188,6 @@ require (
 	golang.org/x/tools v0.1.10 // indirect
 	golang.org/x/xerrors v0.0.0-20220517211312-f3a8303e98df // indirect
 	google.golang.org/genproto v0.0.0-20220519153652-3a47de7e79bd // indirect
-	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/ini.v1 v1.66.4 // indirect
 	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect

go.sum

@@ -153,6 +153,7 @@ func NewNode(ctx context.Context, conf config.NodeConfig, p2pKey crypto.PrivKey,
 
 	node.P2P.SetTxValidator(node.newTxValidator())
 	node.P2P.SetHeaderValidator(node.newHeaderValidator())
+	node.P2P.SetFraudProofValidator(node.newFraudProofValidator())
 
 	return node, nil
 }
@@ -321,6 +322,23 @@ func (n *Node) newHeaderValidator() p2p.GossipValidator {
 	}
 }
 
+// newFraudProofValidator returns a pubsub validator that runs basic checks and forwards
+// the deserialized header for further processing
+func (n *Node) newFraudProofValidator() p2p.GossipValidator {
+	return func(fraudProofMsg *p2p.GossipMessage) bool {
+		n.Logger.Debug("fraud proof received", "from", fraudProofMsg.From, "bytes", len(fraudProofMsg.Data))
+		var fraudProof types.FraudProof
+		err := fraudProof.UnmarshalBinary(fraudProofMsg.Data)
+		if err != nil {
+			n.Logger.Error("failed to deserialize fraud proof", "error", err)
+			return false
+		}
+		// TODO(manav): Add validation checks for fraud proof here
+		n.blockManager.FraudProofCh <- &fraudProof
+		return true
+	}
+}
+
 func createAndStartIndexerService(
 	conf config.NodeConfig,
 	kvStore store.KVStore,

node/node.go

@@ -38,6 +38,8 @@ const (
 
 	// headerTopicSuffix is added after namespace to create pubsub topic for block header gossiping.
 	headerTopicSuffix = "-header"
+
+	fraudProofTopicSuffix = "-fraudProof"
 )
 
 // Client is a P2P client, implemented with libp2p.
@@ -60,6 +62,9 @@ type Client struct {
 	headerGossiper  *Gossiper
 	headerValidator GossipValidator
 
+	fraudProofGossiper  *Gossiper
+	fraudProofValidator GossipValidator
+
 	// cancel is used to cancel context passed to libp2p functions
 	// it's required because of discovery.Advertise call
 	cancel context.CancelFunc
@@ -138,6 +143,7 @@ func (c *Client) Close() error {
 	return multierr.Combine(
 		c.txGossiper.Close(),
 		c.headerGossiper.Close(),
+		c.fraudProofGossiper.Close(),
 		c.dht.Close(),
 		c.host.Close(),
 	)
@@ -165,6 +171,17 @@ func (c *Client) SetHeaderValidator(validator GossipValidator) {
 	c.headerValidator = validator
 }
 
+// GossipHeader sends a fraud proof to the P2P network.
+func (c *Client) GossipFraudProof(ctx context.Context, fraudProof []byte) error {
+	c.logger.Debug("Gossiping fraud proof", "len", len(fraudProof))
+	return c.fraudProofGossiper.Publish(ctx, fraudProof)
+}
+
+// SetFraudProofValidator sets the callback function, that will be invoked after a fraud proof is received from P2P network.
+func (c *Client) SetFraudProofValidator(validator GossipValidator) {
+	c.fraudProofValidator = validator
+}
+
 func (c *Client) Addrs() []multiaddr.Multiaddr {
 	return c.host.Addrs()
 }
@@ -316,6 +333,13 @@ func (c *Client) setupGossiping(ctx context.Context) error {
 	}
 	go c.headerGossiper.ProcessMessages(ctx)
 
+	c.fraudProofGossiper, err = NewGossiper(c.host, ps, c.getFraudProofTopic(), c.logger,
+		WithValidator(c.fraudProofValidator))
+	if err != nil {
+		return err
+	}
+	go c.fraudProofGossiper.ProcessMessages(ctx)
+
 	return nil
 }
 
@@ -356,3 +380,7 @@ func (c *Client) getTxTopic() string {
 func (c *Client) getHeaderTopic() string {
 	return c.getNamespace() + headerTopicSuffix
 }
+
+func (c *Client) getFraudProofTopic() string {
+	return c.getNamespace() + fraudProofTopicSuffix
+}

p2p/client.go

@@ -74,3 +74,17 @@ message Block {
 	Data data = 2;
 	Commit last_commit = 3;
 }
+
+message FraudProof {
+  uint64 block_height = 1;
+  StateWitness state_witness = 2;
+}
+
+message StateWitness {
+   repeated WitnessData witness_data = 1;
+}
+
+message WitnessData {
+  bytes key = 1;
+  bytes value = 2;
+}

proto/optimint/optimint.proto

@@ -89,3 +89,17 @@ type Signature []byte
 type IntermediateStateRoots struct {
 	RawRootsList [][]byte
 }
+
+type FraudProof struct {
+	BlockHeight  uint64
+	StateWitness StateWitness
+}
+
+type StateWitness struct {
+	WitnessData []WitnessData
+}
+
+type WitnessData struct {
+	Key   []byte
+	Value []byte
+}