Add proof validation to batch poster

arbnode/batch_poster.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"encoding/binary"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math"
@@ -36,6 +37,7 @@ import (
 
 	hotshotClient "github.com/EspressoSystems/espresso-sequencer-go/client"
 	lightclient "github.com/EspressoSystems/espresso-sequencer-go/light-client"
+	"github.com/offchainlabs/nitro/espressocrypto"
 
 	"github.com/offchainlabs/nitro/arbnode/dataposter"
 	"github.com/offchainlabs/nitro/arbnode/dataposter/storage"
@@ -608,7 +610,37 @@ func (b *BatchPoster) addEspressoBlockMerkleProof(
 	} else {
 		newMsg, err = arbos.MessageFromEspresso(msg.Message.Header, txs, jst)
 		if err != nil {
-			return err
+			return fmt.Errorf("error fetching the block merkle proof for validated height %v and leaf height %v. Request failed with error %w", snapshot.Height, jst.Header.Header.GetBlockHeight(), err)
+		}
+		jst.BlockMerkleJustification = &arbostypes.BlockMerkleJustification{BlockMerkleProof: &proof, BlockMerkleComm: nextHeader.Header.GetBlockMerkleTreeRoot()}
+
+		log.Info("About to validate merkle and namespace proofs for msg count with batch relevant to l1 height", "msg count", b.building.msgCount, "l1 height", msg.Message.Header.BlockNumber)
+
+		// Validate espresso proofs.
+		json_header, err := json.Marshal(jst.Header)
+		if err != nil {
+			return fmt.Errorf("Failed to Marshal the jst Header")
+		}
+
+		valid_proof := espressocrypto.VerifyMerkleProof(proof.Proof, json_header, *jst.BlockMerkleJustification.BlockMerkleComm, snapshot.Root)
+		valid_namespace := espressocrypto.VerifyNamespace(arbOSConfig.ChainID.Uint64(), *jst.Proof, *jst.Header.Header.GetPayloadCommitment(), *jst.Header.Header.GetNsTable(), txs, *jst.VidCommon)
+		if !(valid_proof && valid_namespace) {
+			return fmt.Errorf("Cannot add Espresso block merkle proof as it is not valid")
+		}
+
+		log.Info("Espresso proofs have been validated!", "msg count", b.building.msgCount, "l1 height", msg.Message.Header.BlockNumber)
+
+		if arbos.IsEspressoSovereignMsg(msg.Message) {
+			// Passing an empty byte slice as payloadSignature because txs[0] already contains the payloadSignature here
+			newMsg, err = arbos.MessageFromEspressoSovereignTx(txs[0], jst, []byte{}, msg.Message.Header)
+			if err != nil {
+				return err
+			}
+		} else {
+			newMsg, err = arbos.MessageFromEspresso(msg.Message.Header, txs, jst)
+			if err != nil {
+				return err
+			}
 		}
 	}
 	msg.Message = &newMsg