Merge pull request #225 from m-Peter/use-evm-dry-run-method

Use `EVM.dryRun` method

api/api.go

@@ -398,13 +398,19 @@ func (b *BlockChainAPI) Call(
 		return handleError[hexutil.Bytes](b.logger, err)
 	}
 
-	txData, err := signTxFromArgs(args)
+	tx, err := encodeTxFromArgs(args)
 	if err != nil {
-		b.logger.Error().Err(err).Msg("failed to sign transaction for call")
+		b.logger.Error().Err(err).Msg("failed to encode transaction for call")
 		return handleError[hexutil.Bytes](b.logger, errs.ErrInternal)
 	}
 
-	res, err := b.evm.Call(ctx, txData, cadenceHeight)
+	// Default address in case user does not provide one
+	from := b.config.Coinbase
+	if args.From != nil {
+		from = *args.From
+	}
+
+	res, err := b.evm.Call(ctx, tx, from, cadenceHeight)
 	if err != nil {
 		b.logger.Error().Err(err).Msg("failed to execute call")
 		return handleError[hexutil.Bytes](b.logger, errs.ErrInternal)
@@ -492,13 +498,19 @@ func (b *BlockChainAPI) EstimateGas(
 	blockNumberOrHash *rpc.BlockNumberOrHash,
 	overrides *StateOverride,
 ) (hexutil.Uint64, error) {
-	txData, err := signTxFromArgs(args)
+	tx, err := encodeTxFromArgs(args)
 	if err != nil {
-		b.logger.Error().Err(err).Msg("failed to sign transaction for gas estimate")
+		b.logger.Error().Err(err).Msg("failed to encode transaction for gas estimate")
 		return hexutil.Uint64(defaultGasLimit), nil // return default gas limit
 	}
 
-	estimatedGas, err := b.evm.EstimateGas(ctx, txData)
+	// Default address in case user does not provide one
+	from := b.config.Coinbase
+	if args.From != nil {
+		from = *args.From
+	}
+
+	estimatedGas, err := b.evm.EstimateGas(ctx, tx, from)
 	if err != nil {
 		b.logger.Error().Err(err).Msg("failed to estimate gas")
 		return hexutil.Uint64(0), err

api/encode_transaction.go

@@ -0,0 +1,48 @@
+package api
+
+import (
+	"math/big"
+
+	"github.com/onflow/go-ethereum/core/types"
+)
+
+const defaultGasLimit uint64 = 15_000_000
+
+// encodeTxFromArgs will create a transaction from the given arguments.
+// The resulting unsigned transaction is only supposed to be used through
+// `EVM.dryRun` inside Cadence scripts, meaning that no state change
+// will occur.
+// This is only useful for `eth_estimateGas` and `eth_call` endpoints.
+func encodeTxFromArgs(args TransactionArgs) ([]byte, error) {
+	var data []byte
+	if args.Data != nil {
+		data = *args.Data
+	} else if args.Input != nil {
+		data = *args.Input
+	}
+
+	// provide a high enough gas for the tx to be able to execute,
+	// capped by the gas set in transaction args.
+	gasLimit := defaultGasLimit
+	if args.Gas != nil {
+		gasLimit = uint64(*args.Gas)
+	}
+
+	value := big.NewInt(0)
+	if args.Value != nil {
+		value = args.Value.ToInt()
+	}
+
+	tx := types.NewTx(
+		&types.LegacyTx{
+			Nonce:    0,
+			To:       args.To,
+			Value:    value,
+			Gas:      gasLimit,
+			GasPrice: big.NewInt(0),
+			Data:     data,
+		},
+	)
+
+	return tx.MarshalBinary()
+}

services/requester/cadence/dry_run.cdc

@@ -0,0 +1,9 @@
+import EVM
+
+access(all)
+fun main(hexEncodedTx: String, hexEncodedAddress: String): EVM.Result {
+    let addressBytes = hexEncodedAddress.decodeHex().toConstantSized<[UInt8; 20]>()!
+    let address = EVM.EVMAddress(bytes: addressBytes)
+
+    return EVM.dryRun(tx: hexEncodedTx.decodeHex(), from: address)
+}

services/requester/requester.go

@@ -27,8 +27,8 @@ import (
 )
 
 var (
-	//go:embed cadence/call.cdc
-	callScript []byte
+	//go:embed cadence/dry_run.cdc
+	dryRunScript []byte
 
 	//go:embed cadence/run.cdc
 	runTxScript []byte
@@ -39,9 +39,6 @@ var (
 	//go:embed cadence/create_coa.cdc
 	createCOAScript []byte
 
-	//go:embed cadence/estimate_gas.cdc
-	estimateGasScript []byte
-
 	//go:embed cadence/get_nonce.cdc
 	getNonceScript []byte
 
@@ -69,12 +66,12 @@ type Requester interface {
 	// Call executes the given signed transaction data on the state for the given block number.
 	// Note, this function doesn't make and changes in the state/blockchain and is
 	// useful to execute and retrieve values.
-	Call(ctx context.Context, data []byte, height uint64) ([]byte, error)
+	Call(ctx context.Context, data []byte, from common.Address, height uint64) ([]byte, error)
 
 	// EstimateGas executes the given signed transaction data on the state.
 	// Note, this function doesn't make any changes in the state/blockchain and is
 	// useful to executed and retrieve the gas consumption and possible failures.
-	EstimateGas(ctx context.Context, data []byte) (uint64, error)
+	EstimateGas(ctx context.Context, data []byte, from common.Address) (uint64, error)
 
 	// GetNonce gets nonce from the network at the given block height.
 	GetNonce(ctx context.Context, address common.Address, height uint64) (uint64, error)
@@ -322,22 +319,28 @@ func (e *EVM) GetNonce(
 func (e *EVM) Call(
 	ctx context.Context,
 	data []byte,
+	from common.Address,
 	height uint64,
 ) ([]byte, error) {
 	hexEncodedTx, err := cadence.NewString(hex.EncodeToString(data))
 	if err != nil {
 		return nil, err
 	}
 
+	hexEncodedAddress, err := addressToCadenceString(from)
+	if err != nil {
+		return nil, err
+	}
+
 	e.logger.Debug().
 		Str("data", fmt.Sprintf("%x", data)).
 		Msg("call")
 
 	scriptResult, err := e.executeScriptAtHeight(
 		ctx,
-		callScript,
+		dryRunScript,
 		height,
-		[]cadence.Value{hexEncodedTx},
+		[]cadence.Value{hexEncodedTx, hexEncodedAddress},
 	)
 	if err != nil {
 		return nil, fmt.Errorf("failed to execute script: %w", err)
@@ -361,7 +364,11 @@ func (e *EVM) Call(
 	return result, nil
 }
 
-func (e *EVM) EstimateGas(ctx context.Context, data []byte) (uint64, error) {
+func (e *EVM) EstimateGas(
+	ctx context.Context,
+	data []byte,
+	from common.Address,
+) (uint64, error) {
 	e.logger.Debug().
 		Str("data", fmt.Sprintf("%x", data)).
 		Msg("estimate gas")
@@ -371,10 +378,15 @@ func (e *EVM) EstimateGas(ctx context.Context, data []byte) (uint64, error) {
 		return 0, err
 	}
 
+	hexEncodedAddress, err := addressToCadenceString(from)
+	if err != nil {
+		return 0, err
+	}
+
 	scriptResult, err := e.client.ExecuteScriptAtLatestBlock(
 		ctx,
-		e.replaceAddresses(estimateGasScript),
-		[]cadence.Value{hexEncodedTx},
+		e.replaceAddresses(dryRunScript),
+		[]cadence.Value{hexEncodedTx, hexEncodedAddress},
 	)
 	if err != nil {
 		return 0, fmt.Errorf("failed to execute script: %w", err)

tests/web3js/eth_transfer_between_eoa_accounts_test.js

@@ -5,19 +5,6 @@ const helpers = require('./helpers')
 const web3 = conf.web3
 
 it('transfer flow between two EOA accounts', async () => {
-  // TODO: Temporary workaround until `EVM.dryRun` is introduced
-  let transferValue = utils.toWei("0.5", "ether")
-  const signedTx = await conf.eoa.signTransaction({
-    from: conf.eoa.address,
-    to: '0xa94f5374Fce5edBC8E2a8697C15331677e6EbF0B',
-    value: transferValue,
-    gasPrice: '0',
-    gasLimit: 55000,
-  })
-  let response = await helpers.callRPCMethod('eth_sendRawTransaction', [signedTx.rawTransaction])
-  assert.equal(200, response.status)
-  assert.isDefined(response.body['result'])
-
   let receiver = web3.eth.accounts.create()
 
   // make sure receiver balance is initially 0
@@ -26,13 +13,12 @@ it('transfer flow between two EOA accounts', async () => {
 
   // get sender balance
   let senderBalance = await web3.eth.getBalance(conf.eoa.address)
-  // we moved some value before, for `eth_call` to work properly with the
-  // test EOA.
-  assert.equal(senderBalance, utils.toWei(conf.fundedAmount, "ether") - transferValue)
+  assert.equal(senderBalance, utils.toWei(conf.fundedAmount, "ether"))
 
   let txCount = await web3.eth.getTransactionCount(conf.eoa.address)
-  assert.equal(1n, txCount)
+  assert.equal(0n, txCount)
 
+  let transferValue = utils.toWei("0.5", "ether")
   let transfer = await helpers.signAndSend({
     from: conf.eoa.address,
     to: receiver.address,
@@ -46,14 +32,14 @@ it('transfer flow between two EOA accounts', async () => {
 
   // check that transaction count was increased
   txCount = await web3.eth.getTransactionCount(conf.eoa.address)
-  assert.equal(2n, txCount)
+  assert.equal(1n, txCount)
 
   // check balance was moved
   receiverWei = await web3.eth.getBalance(receiver.address)
   assert.equal(receiverWei, transferValue)
 
   senderBalance = await web3.eth.getBalance(conf.eoa.address)
-  assert.equal(senderBalance, utils.toWei(conf.fundedAmount, "ether") - (2*transferValue))
+  assert.equal(senderBalance, utils.toWei(conf.fundedAmount, "ether") - transferValue)
 
   // make sure latest block includes the transfer tx
   let latest = await web3.eth.getBlockNumber()
@@ -63,7 +49,7 @@ it('transfer flow between two EOA accounts', async () => {
 
   // check that getTransactionCount can handle specific block heights
   txCount = await web3.eth.getTransactionCount(conf.eoa.address, latest - 1n)
-  assert.equal(1n, txCount)
+  assert.equal(0n, txCount)
 
   // get balance at special block tags
   let blockTags = ["latest", "pending", "safe", "finalized"]