// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package core
import (
"math"
"math/big"
"github.com/ava-labs/coreth/core/vm"
"github.com/ava-labs/coreth/params"
"github.com/ethereum/go-ethereum/common"
)
/*
The State Transitioning Model
A state transition is a change made when a transaction is applied to the current world state
The state transitioning model does all the necessary work to work out a valid new state root.
1) Nonce handling
2) Pre pay gas
3) Create a new state object if the recipient is \0*32
4) Value transfer
== If contract creation ==
4a) Attempt to run transaction data
4b) If valid, use result as code for the new state object
== end ==
5) Run Script section
6) Derive new state root
*/
type StateTransition struct {
gp *GasPool
msg Message
gas uint64
gasPrice *big.Int
initialGas uint64
value *big.Int
data []byte
state vm.StateDB
evm *vm.EVM
}
// Message represents a message sent to a contract.
type Message interface {
From() common.Address
To() *common.Address
GasPrice() *big.Int
Gas() uint64
Value() *big.Int
Nonce() uint64
CheckNonce() bool
Data() []byte
}
// ExecutionResult includes all output after executing given evm
// message no matter the execution itself is successful or not.
type ExecutionResult struct {
UsedGas uint64 // Total used gas but include the refunded gas
Err error // Any error encountered during the execution(listed in core/vm/errors.go)
ReturnData []byte // Returned data from evm(function result or data supplied with revert opcode)
}
// Unwrap returns the internal evm error which allows us for further
// analysis outside.
func (result *ExecutionResult) Unwrap() error {
return result.Err
}
// Failed returns the indicator whether the execution is successful or not
func (result *ExecutionResult) Failed() bool { return result.Err != nil }
// Return is a helper function to help caller distinguish between revert reason
// and function return. Return returns the data after execution if no error occurs.
func (result *ExecutionResult) Return() []byte {
if result.Err != nil {
return nil
}
return common.CopyBytes(result.ReturnData)
}
// Revert returns the concrete revert reason if the execution is aborted by `REVERT`
// opcode. Note the reason can be nil if no data supplied with revert opcode.
func (result *ExecutionResult) Revert() []byte {
if result.Err != vm.ErrExecutionReverted {
return nil
}
return common.CopyBytes(result.ReturnData)
}
// IntrinsicGas computes the 'intrinsic gas' for a message with the given data.
func IntrinsicGas(data []byte, contractCreation, isHomestead bool, isEIP2028 bool) (uint64, error) {
// Set the starting gas for the raw transaction
var gas uint64
if contractCreation && isHomestead {
gas = params.TxGasContractCreation
} else {
gas = params.TxGas
}
// Bump the required gas by the amount of transactional data
if len(data) > 0 {
// Zero and non-zero bytes are priced differently
var nz uint64
for _, byt := range data {
if byt != 0 {
nz++
}
}
// Make sure we don't exceed uint64 for all data combinations
nonZeroGas := params.TxDataNonZeroGasFrontier
if isEIP2028 {
nonZeroGas = params.TxDataNonZeroGasEIP2028
}
if (math.MaxUint64-gas)/nonZeroGas < nz {
return 0, ErrGasUintOverflow
}
gas += nz * nonZeroGas
z := uint64(len(data)) - nz
if (math.MaxUint64-gas)/params.TxDataZeroGas < z {
return 0, ErrGasUintOverflow
}
gas += z * params.TxDataZeroGas
}
return gas, nil
}
// NewStateTransition initialises and returns a new state transition object.
func NewStateTransition(evm *vm.EVM, msg Message, gp *GasPool) *StateTransition {
return &StateTransition{
gp: gp,
evm: evm,
msg: msg,
gasPrice: msg.GasPrice(),
value: msg.Value(),
data: msg.Data(),
state: evm.StateDB,
}
}
// ApplyMessage computes the new state by applying the given message
// against the old state within the environment.
//
// ApplyMessage returns the bytes returned by any EVM execution (if it took place),
// the gas used (which includes gas refunds) and an error if it failed. An error always
// indicates a core error meaning that the message would always fail for that particular
// state and would never be accepted within a block.
func ApplyMessage(evm *vm.EVM, msg Message, gp *GasPool) (*ExecutionResult, error) {
return NewStateTransition(evm, msg, gp).TransitionDb()
}
// to returns the recipient of the message.
func (st *StateTransition) to() common.Address {
if st.msg == nil || st.msg.To() == nil /* contract creation */ {
return common.Address{}
}
return *st.msg.To()
}
func (st *StateTransition) buyGas() error {
mgval := new(big.Int).Mul(new(big.Int).SetUint64(st.msg.Gas()), st.gasPrice)
if st.state.GetBalance(st.msg.From()).Cmp(mgval) < 0 {
return ErrInsufficientFunds
}
if err := st.gp.SubGas(st.msg.Gas()); err != nil {
return err
}
st.gas += st.msg.Gas()
st.initialGas = st.msg.Gas()
st.state.SubBalance(st.msg.From(), mgval)
return nil
}
func (st *StateTransition) preCheck() error {
// Make sure this transaction's nonce is correct.
if st.msg.CheckNonce() {
nonce