levm

README

LEVM - Little Ethereum Virtual Machine

Run smart contracts on the Ethereum Virtual Machine (EVM) without the Ethereum blockchain.

I created this to make it a little easier to use the EVM in other projects, and for testing smart contracts.

levm.New(...) creates a small wrapper for the ethereum virtual machine, and sets up the EVM with default parameters and the required stateDB.

↓ Installation

This project only has two dependencies. (go-ethereum contains the EVM, and splashkeys is an ecdsa key library)

go get github.com/CryptoKass/levm

Dependencies

• go get github.com/ethereum/go-ethereum
• go get github.com/CryptoKass/splashkeys

Example

This is Example is located in the example sub-directory:

func main() {

	//make a new address evm
	fromAddr = tools.NewRandomAddress()

	//Load a contract from file
	abiObject, binData, err := tools.LoadContract("contract/example_sol_Example.abi", "contract/example_sol_Example.bin")
	fmt.Println("Abi\n", abiObject.Methods)

	// create new LEVM instance
	lvm := levm.New("./db", big.NewInt(0), fromAddr)

	// create a new account and set the balance
	// (needs enough balance to cover gas cost)
	lvm.NewAccount(fromAddr, big.NewInt(1e18))

	// deploy a contract
	code, addr, gas, err := lvm.DeployContract(fromAddr, binData)
	fmt.Println("contract code length:", len(code))
	fmt.Printf("contract address: %x\n", addr)
	fmt.Println("unused gas:", gas)
	fmt.Println("errors:", err)

}

contact: kasscrypto@gmail.com 👍

HELP WANTED would be great if you would create an issue if you find a bug.

Documentation

Overview

Package levm is a higher level wrapper for the EVM and the related StateDB. levm.go contains methods for creating the LEVM and deploying/calling contracts. db.go contains methods for interacting with the stateDB i.e. getting accounts and balances

Index

• type Account
• type LEVM
  • func New(dbPath string, blockNumber *big.Int, origin common.Address) *LEVM
  • func (lvm *LEVM) CallContract(callerAddr, contractAddr common.Address, value *big.Int, inputs []byte) ([]byte, error)
  • func (lvm *LEVM) CallContractABI(callerAddr, contractAddr common.Address, value *big.Int, abiObject abi.ABI, ...) ([]byte, error)
  • func (lvm *LEVM) DB() *state.StateDB
  • func (lvm *LEVM) DeployContract(fromAddr common.Address, contractData []byte) ([]byte, common.Address, uint64, error)
  • func (lvm *LEVM) GetAccount(addr common.Address) Account
  • func (lvm *LEVM) NewAccount(addr common.Address, balance *big.Int)
  • func (lvm *LEVM) NewEVM(blockNumber *big.Int, origin common.Address)
  • func (lvm *LEVM) SetAccount(addr common.Address, acc Account)

Types

type Account

type Account struct {
	Balance *big.Int
	Nonce   uint64
	Code    []byte
}

Account is a simple representation of an account in the stateDB, for further controls call DB() to retrieve the db reference itself. Almost as a snapshot

type LEVM

type LEVM struct {
	// contains filtered or unexported fields
}

LEVM is a container for the go-ethereum EVM with methods to create and call contracts.

LEVM contains the two most important objects for interacting with the EVM: stateDB and vm.EVM. The LEVM should be created with the LEVM.New() method, unless you know what you doing.

func New

func New(dbPath string, blockNumber *big.Int, origin common.Address) *LEVM

New creates a new instace of the LEVM

func (*LEVM) CallContract

func (lvm *LEVM) CallContract(callerAddr, contractAddr common.Address, value *big.Int, inputs []byte) ([]byte, error)

CallContract - make a call to a Contract Method using prepacked Inputs. To use ABI directly try lvm.CallContractABI()

func (*LEVM) CallContractABI

func (lvm *LEVM) CallContractABI(callerAddr, contractAddr common.Address, value *big.Int, abiObject abi.ABI, funcName string, args ...interface{}) ([]byte, error)

CallContractABI - make a call to a Contract Method using the ABI.

func (*LEVM) DB

func (lvm *LEVM) DB() *state.StateDB

DB returns a pointer to the vm's state DB.

func (*LEVM) DeployContract

func (lvm *LEVM) DeployContract(fromAddr common.Address, contractData []byte) ([]byte, common.Address, uint64, error)

DeployContract will create and deploy a new contract from the contract data.

func (*LEVM) GetAccount

func (lvm *LEVM) GetAccount(addr common.Address) Account

GetAccount returns a copy of stateDB

func (*LEVM) NewAccount

func (lvm *LEVM) NewAccount(addr common.Address, balance *big.Int)

NewAccount Create a new Account and Set its balance

func (*LEVM) NewEVM

func (lvm *LEVM) NewEVM(blockNumber *big.Int, origin common.Address)

NewEVM creates a fresh evm instance with new origin and blocknumber and time. This method recreates the contained EVM while keeping the stateDB the same.

func (*LEVM) SetAccount

func (lvm *LEVM) SetAccount(addr common.Address, acc Account)

SetAccount will update the statedb with related values contained in the Account snapshot.