bbc4ea4ae8
The run loop, which previously contained custom opcode executes have been removed and has been simplified to a few checks. Each operation consists of 4 elements: execution function, gas cost function, stack validation function and memory size function. The execution function implements the operation's runtime behaviour, the gas cost function implements the operation gas costs function and greatly depends on the memory and stack, the stack validation function validates the stack and makes sure that enough items can be popped off and pushed on and the memory size function calculates the memory required for the operation and returns it. This commit also allows the EVM to go unmetered. This is helpful for offline operations such as contract calls.
128 lines
4.0 KiB
Go
128 lines
4.0 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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"github.com/ethereum/go-ethereum/params"
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)
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// Precompiled contract is the basic interface for native Go contracts. The implementation
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// requires a deterministic gas count based on the input size of the Run method of the
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// contract.
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type PrecompiledContract interface {
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RequiredGas(inputSize int) *big.Int // RequiredPrice calculates the contract gas use
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Run(input []byte) []byte // Run runs the precompiled contract
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}
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// Precompiled contains the default set of ethereum contracts
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var PrecompiledContracts = map[common.Address]PrecompiledContract{
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common.BytesToAddress([]byte{1}): &ecrecover{},
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common.BytesToAddress([]byte{2}): &sha256{},
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common.BytesToAddress([]byte{3}): &ripemd160{},
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common.BytesToAddress([]byte{4}): &dataCopy{},
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}
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// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
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func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
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gas := p.RequiredGas(len(input))
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if contract.UseGas(gas) {
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ret = p.Run(input)
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return ret, nil
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} else {
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return nil, ErrOutOfGas
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}
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}
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// ECRECOVER implemented as a native contract
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type ecrecover struct{}
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func (c *ecrecover) RequiredGas(inputSize int) *big.Int {
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return params.EcrecoverGas
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}
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func (c *ecrecover) Run(in []byte) []byte {
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const ecRecoverInputLength = 128
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in = common.RightPadBytes(in, ecRecoverInputLength)
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// "in" is (hash, v, r, s), each 32 bytes
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// but for ecrecover we want (r, s, v)
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r := common.BytesToBig(in[64:96])
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s := common.BytesToBig(in[96:128])
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v := in[63] - 27
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// tighter sig s values in homestead only apply to tx sigs
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if common.Bytes2Big(in[32:63]).BitLen() > 0 || !crypto.ValidateSignatureValues(v, r, s, false) {
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glog.V(logger.Detail).Infof("ECRECOVER error: v, r or s value invalid")
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return nil
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}
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// v needs to be at the end for libsecp256k1
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pubKey, err := crypto.Ecrecover(in[:32], append(in[64:128], v))
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// make sure the public key is a valid one
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if err != nil {
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glog.V(logger.Detail).Infoln("ECRECOVER error: ", err)
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return nil
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}
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// the first byte of pubkey is bitcoin heritage
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return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32)
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}
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// SHA256 implemented as a native contract
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type sha256 struct{}
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func (c *sha256) RequiredGas(inputSize int) *big.Int {
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n := big.NewInt(int64(inputSize+31) / 32)
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n.Mul(n, params.Sha256WordGas)
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return n.Add(n, params.Sha256Gas)
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}
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func (c *sha256) Run(in []byte) []byte {
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return crypto.Sha256(in)
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}
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// RIPMED160 implemented as a native contract
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type ripemd160 struct{}
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func (c *ripemd160) RequiredGas(inputSize int) *big.Int {
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n := big.NewInt(int64(inputSize+31) / 32)
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n.Mul(n, params.Ripemd160WordGas)
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return n.Add(n, params.Ripemd160Gas)
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}
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func (c *ripemd160) Run(in []byte) []byte {
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return common.LeftPadBytes(crypto.Ripemd160(in), 32)
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}
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// data copy implemented as a native contract
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type dataCopy struct{}
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func (c *dataCopy) RequiredGas(inputSize int) *big.Int {
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n := big.NewInt(int64(inputSize+31) / 32)
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n.Mul(n, params.IdentityWordGas)
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return n.Add(n, params.IdentityGas)
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}
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func (c *dataCopy) Run(in []byte) []byte {
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return in
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}
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