fix: Consider all transactions in chunk hash (#62)

* fix: Consider all transactions in chunk hash

* adjust

* nit

Author: Thegaram

encoding/codecv7_test.go

@@ -48,6 +48,44 @@ func TestDecodeAllDeadlock(t *testing.T) {
 	}
 }
 
+// TestChunkHashUnique tests that the hashes of any two different chunks are different.
+func TestChunkHashUnique(t *testing.T) {
+	// construct a chunk with a single, empty block
+	chunk1 := newDAChunkV7([]DABlock{&daBlockV7{
+		daBlockV0: daBlockV0{
+			number:          1,
+			timestamp:       0,
+			baseFee:         big.NewInt(0),
+			gasLimit:        0,
+			numTransactions: 0,
+			numL1Messages:   0,
+		},
+		lowestL1MessageQueueIndex: 0,
+	}}, [][]*types.TransactionData{{}})
+
+	chunkHash1, err := chunk1.Hash()
+	require.NoError(t, err)
+
+	// construct a 2nd chunk with a single, empty block,
+	// the only difference is the block number.
+	chunk2 := newDAChunkV7([]DABlock{&daBlockV7{
+		daBlockV0: daBlockV0{
+			number:          2,
+			timestamp:       0,
+			baseFee:         big.NewInt(0),
+			gasLimit:        0,
+			numTransactions: 0,
+			numL1Messages:   0,
+		},
+		lowestL1MessageQueueIndex: 0,
+	}}, [][]*types.TransactionData{{}})
+
+	chunkHash2, err := chunk2.Hash()
+	require.NoError(t, err)
+
+	require.NotEqual(t, chunkHash1, chunkHash2)
+}
+
 // TestCodecV7DABlockEncodeDecode tests the encoding and decoding of daBlockV7.
 func TestCodecV7DABlockEncodeDecode(t *testing.T) {
 	codecV7, err := CodecFromVersion(CodecV7)

encoding/codecv7_types.go

@@ -447,22 +447,26 @@ func newDAChunkV7(blocks []DABlock, transactions [][]*types.TransactionData) *da
 }
 
 // Hash computes the hash of the DAChunk data.
+// Note: Starting from v7, the chunk hash is not used in
+// the protocol anymore, it is simply a unique identifier.
 func (c *daChunkV7) Hash() (common.Hash, error) {
 	var dataBytes []byte
 
 	// concatenate block contexts
 	for _, block := range c.blocks {
+		// append block number
+		var tmp [8]byte
+		binary.BigEndian.PutUint64(tmp[:], block.Number())
+		dataBytes = append(dataBytes, tmp[:]...)
+
+		// append encoded block context
 		encodedBlock := block.Encode()
 		dataBytes = append(dataBytes, encodedBlock...)
 	}
 
-	// concatenate l1 tx hashes
+	// concatenate tx hashes
 	for _, blockTxs := range c.transactions {
 		for _, txData := range blockTxs {
-			if txData.Type != types.L1MessageTxType {
-				continue
-			}
-
 			hashBytes := common.FromHex(txData.TxHash)
 			if len(hashBytes) != common.HashLength {
 				return common.Hash{}, fmt.Errorf("unexpected hash: %s", txData.TxHash)