Merge pull request #5 from maticnetwork/bor-fees

Bor fees

core/evm.go

@@ -92,6 +92,17 @@ func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool {
 
 // Transfer subtracts amount from sender and adds amount to recipient using the given Db
 func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) {
+	// get inputs before
+	input1 := db.GetBalance(sender)
+	input2 := db.GetBalance(recipient)
+
 	db.SubBalance(sender, amount)
 	db.AddBalance(recipient, amount)
+
+	// get outputs after
+	output1 := db.GetBalance(sender)
+	output2 := db.GetBalance(recipient)
+
+	// add transfer log
+	AddTransferLog(db, sender, recipient, amount, input1, input2, output1, output2)
 }

core/state_transition.go

@@ -22,6 +22,7 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
@@ -31,6 +32,10 @@ var (
 	errInsufficientBalanceForGas = errors.New("insufficient balance to pay for gas")
 )
 
+var transferLogSig = common.HexToHash("0xe6497e3ee548a3372136af2fcb0696db31fc6cf20260707645068bd3fe97f3c4")
+var transferFeeLogSig = common.HexToHash("0x4dfe1bbbcf077ddc3e01291eea2d5c70c2b422b415d95645b9adcfd678cb1d63")
+var feeAddress = common.HexToAddress("0x0000000000000000000000000000000000001010")
+
 /*
 The State Transitioning Model
 
@@ -181,6 +186,9 @@ func (st *StateTransition) preCheck() error {
 // returning the result including the used gas. It returns an error if failed.
 // An error indicates a consensus issue.
 func (st *StateTransition) TransitionDb() (ret []byte, usedGas uint64, failed bool, err error) {
+	input1 := st.state.GetBalance(st.msg.From())
+	input2 := st.state.GetBalance(st.evm.Coinbase)
+
 	if err = st.preCheck(); err != nil {
 		return
 	}
@@ -224,6 +232,24 @@ func (st *StateTransition) TransitionDb() (ret []byte, usedGas uint64, failed bo
 	st.refundGas()
 	st.state.AddBalance(st.evm.Coinbase, new(big.Int).Mul(new(big.Int).SetUint64(st.gasUsed()), st.gasPrice))
 
+	amount := new(big.Int).Mul(new(big.Int).SetUint64(st.gasUsed()), st.gasPrice)
+	output1 := new(big.Int).SetBytes(input1.Bytes())
+	output2 := new(big.Int).SetBytes(input2.Bytes())
+
+	// add transfer log
+	AddFeeTransferLog(
+		st.state,
+
+		msg.From(),
+		st.evm.Coinbase,
+
+		amount,
+		input1,
+		input2,
+		output1.Sub(output1, amount),
+		output2.Add(output2, amount),
+	)
+
 	return ret, st.gasUsed(), vmerr != nil, err
 }
 
@@ -248,3 +274,99 @@ func (st *StateTransition) refundGas() {
 func (st *StateTransition) gasUsed() uint64 {
 	return st.initialGas - st.gas
 }
+
+// AddTransferLog adds transfer log into state
+func AddTransferLog(
+	state vm.StateDB,
+
+	sender,
+	recipient common.Address,
+
+	amount,
+	input1,
+	input2,
+	output1,
+	output2 *big.Int,
+) {
+	addTransferLog(
+		state,
+		transferLogSig,
+
+		sender,
+		recipient,
+
+		amount,
+		input1,
+		input2,
+		output1,
+		output2,
+	)
+}
+
+// AddFeeTransferLog adds transfer log into state
+func AddFeeTransferLog(
+	state vm.StateDB,
+
+	sender,
+	recipient common.Address,
+
+	amount,
+	input1,
+	input2,
+	output1,
+	output2 *big.Int,
+) {
+	addTransferLog(
+		state,
+		transferFeeLogSig,
+
+		sender,
+		recipient,
+
+		amount,
+		input1,
+		input2,
+		output1,
+		output2,
+	)
+}
+
+// addTransferLog adds transfer log into state
+func addTransferLog(
+	state vm.StateDB,
+	eventSig common.Hash,
+
+	sender,
+	recipient common.Address,
+
+	amount,
+	input1,
+	input2,
+	output1,
+	output2 *big.Int,
+) {
+	dataInputs := []*big.Int{
+		amount,
+		input1,
+		input2,
+		output1,
+		output2,
+	}
+
+	var data []byte
+	for _, v := range dataInputs {
+		data = append(data, common.LeftPadBytes(v.Bytes(), 32)...)
+	}
+
+	// add transfer log
+	state.AddLog(&types.Log{
+		Address: feeAddress,
+		Topics: []common.Hash{
+			eventSig,
+			feeAddress.Hash(),
+			sender.Hash(),
+			recipient.Hash(),
+		},
+		Data: data,
+	})
+}