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,
+ })
+}