relay eth_getTransactionCount to trusted seq when block pending

jsonrpc/codec.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/0xPolygonHermez/zkevm-node/encoding"
+	"github.com/0xPolygonHermez/zkevm-node/hex"
 	"github.com/jackc/pgx/v4"
 )
 
@@ -167,6 +168,19 @@ func (b *BlockNumber) getNumericBlockNumber(ctx context.Context, s stateInterfac
 	}
 }
 
+func (b *BlockNumber) StringOrHex() string {
+	switch *b {
+	case EarliestBlockNumber:
+		return Earliest
+	case PendingBlockNumber:
+		return Pending
+	case LatestBlockNumber:
+		return Latest
+	default:
+		return hex.EncodeUint64(uint64(*b))
+	}
+}
+
 func stringToBlockNumber(str string) (BlockNumber, error) {
 	str = strings.Trim(str, "\"")
 	switch str {

jsonrpc/codec_test.go

@@ -215,6 +215,24 @@ func TestIndexUnmarshalJSON(t *testing.T) {
 	}
 }
 
+func TestBlockNumberStringOrHex(t *testing.T) {
+	testCases := []struct {
+		bn             *BlockNumber
+		expectedResult string
+	}{
+		{bn: bnPtr(BlockNumber(-3)), expectedResult: "pending"},
+		{bn: bnPtr(BlockNumber(-2)), expectedResult: "latest"},
+		{bn: bnPtr(BlockNumber(-1)), expectedResult: "earliest"},
+		{bn: bnPtr(BlockNumber(0)), expectedResult: "0x0"},
+		{bn: bnPtr(BlockNumber(100)), expectedResult: "0x64"},
+	}
+
+	for _, testCase := range testCases {
+		result := testCase.bn.StringOrHex()
+		assert.Equal(t, testCase.expectedResult, result)
+	}
+}
+
 func bnPtr(bn BlockNumber) *BlockNumber {
 	return &bn
 }

jsonrpc/endpoints_eth.go

@@ -465,7 +465,11 @@ func (e *EthEndpoints) GetTransactionCount(address common.Address, number *Block
 		var nonce uint64
 		var err error
 		if number != nil && *number == PendingBlockNumber {
-			pendingNonce, err = e.pool.GetNonce(ctx, address)
+			if e.cfg.SequencerNodeURI != "" {
+				return e.getTransactionCountFromSequencerNode(address, number)
+			} else {
+				pendingNonce, err = e.pool.GetNonce(ctx, address)
+			}
 			if err != nil {
 				return rpcErrorResponse(defaultErrorCode, "failed to count pending transactions", err)
 			}
@@ -491,6 +495,24 @@ func (e *EthEndpoints) GetTransactionCount(address common.Address, number *Block
 	})
 }
 
+func (e *EthEndpoints) getTransactionCountFromSequencerNode(address common.Address, number *BlockNumber) (interface{}, rpcError) {
+	res, err := JSONRPCCall(e.cfg.SequencerNodeURI, "eth_getTransactionCount", address.String(), number.StringOrHex())
+	if err != nil {
+		return rpcErrorResponse(defaultErrorCode, "failed to get nonce from sequencer node", err)
+	}
+
+	if res.Error != nil {
+		return rpcErrorResponse(res.Error.Code, res.Error.Message, nil)
+	}
+
+	var nonce argUint64
+	err = json.Unmarshal(res.Result, &nonce)
+	if err != nil {
+		return rpcErrorResponse(defaultErrorCode, "failed to read nonce from sequencer node", err)
+	}
+	return nonce, nil
+}
+
 // GetBlockTransactionCountByHash returns the number of transactions in a
 // block from a block matching the given block hash.
 func (e *EthEndpoints) GetBlockTransactionCountByHash(hash common.Hash) (interface{}, rpcError) {