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// 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 vm
import (
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/params"
)
// Precompiled contract is the basic interface for native Go contracts. The implementation
// requires a deterministic gas count based on the input size of the Run method of the
// contract.
type PrecompiledContract interface {
RequiredGas(inputSize int) uint64 // RequiredPrice calculates the contract gas use
Run(input []byte) []byte // Run runs the precompiled contract
}
// Precompiled contains the default set of ethereum contracts
var PrecompiledContracts = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256{},
common.BytesToAddress([]byte{3}): &ripemd160{},
common.BytesToAddress([]byte{4}): &dataCopy{},
}
// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
gas := p.RequiredGas(len(input))
if contract.UseGas(gas) {
ret = p.Run(input)
return ret, nil
} else {
return nil, ErrOutOfGas
}
}
// ECRECOVER implemented as a native contract
type ecrecover struct{}
func (c *ecrecover) RequiredGas(inputSize int) uint64 {
return params.EcrecoverGas
}
func (c *ecrecover) Run(in []byte) []byte {
const ecRecoverInputLength = 128
in = common.RightPadBytes(in, ecRecoverInputLength)
// "in" is (hash, v, r, s), each 32 bytes
// but for ecrecover we want (r, s, v)
r := common.BytesToBig(in[64:96])
s := common.BytesToBig(in[96:128])
v := in[63] - 27
// tighter sig s values in homestead only apply to tx sigs
if common.Bytes2Big(in[32:63]).BitLen() > 0 || !crypto.ValidateSignatureValues(v, r, s, false) {
glog.V(logger.Detail).Infof("ECRECOVER error: v, r or s value invalid")
return nil
}
// v needs to be at the end for libsecp256k1
pubKey, err := crypto.Ecrecover(in[:32], append(in[64:128], v))
// make sure the public key is a valid one
if err != nil {
glog.V(logger.Detail).Infoln("ECRECOVER error: ", err)
return nil
}
// the first byte of pubkey is bitcoin heritage
return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32)
}
// SHA256 implemented as a native contract
type sha256 struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *sha256) RequiredGas(inputSize int) uint64 {
return uint64(inputSize+31)/32*params.Sha256WordGas + params.Sha256Gas
}
func (c *sha256) Run(in []byte) []byte {
return crypto.Sha256(in)
}
// RIPMED160 implemented as a native contract
type ripemd160 struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *ripemd160) RequiredGas(inputSize int) uint64 {
return uint64(inputSize+31)/32*params.Ripemd160WordGas + params.Ripemd160Gas
}
func (c *ripemd160) Run(in []byte) []byte {
return common.LeftPadBytes(crypto.Ripemd160(in), 32)
}
// data copy implemented as a native contract
type dataCopy struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *dataCopy) RequiredGas(inputSize int) uint64 {
return uint64(inputSize+31)/32*params.IdentityWordGas + params.IdentityGas
}
func (c *dataCopy) Run(in []byte) []byte {
return in
}
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