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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 (
"math/big"
"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"
)
// PrecompiledAccount represents a native ethereum contract
type PrecompiledAccount struct {
Gas func(l int) *big.Int
fn func(in []byte) []byte
}
// Call calls the native function
func (self PrecompiledAccount) Call(in []byte) []byte {
return self.fn(in)
}
// Precompiled contains the default set of ethereum contracts
var Precompiled = PrecompiledContracts()
// PrecompiledContracts returns the default set of precompiled ethereum
// contracts defined by the ethereum yellow paper.
func PrecompiledContracts() map[string]*PrecompiledAccount {
return map[string]*PrecompiledAccount{
// ECRECOVER
string(common.LeftPadBytes([]byte{1}, 20)): &PrecompiledAccount{func(l int) *big.Int {
return params.EcrecoverGas
}, ecrecoverFunc},
// SHA256
string(common.LeftPadBytes([]byte{2}, 20)): &PrecompiledAccount{func(l int) *big.Int {
n := big.NewInt(int64(l+31) / 32)
n.Mul(n, params.Sha256WordGas)
return n.Add(n, params.Sha256Gas)
}, sha256Func},
// RIPEMD160
string(common.LeftPadBytes([]byte{3}, 20)): &PrecompiledAccount{func(l int) *big.Int {
n := big.NewInt(int64(l+31) / 32)
n.Mul(n, params.Ripemd160WordGas)
return n.Add(n, params.Ripemd160Gas)
}, ripemd160Func},
string(common.LeftPadBytes([]byte{4}, 20)): &PrecompiledAccount{func(l int) *big.Int {
n := big.NewInt(int64(l+31) / 32)
n.Mul(n, params.IdentityWordGas)
return n.Add(n, params.IdentityGas)
}, memCpy},
}
}
func sha256Func(in []byte) []byte {
return crypto.Sha256(in)
}
func ripemd160Func(in []byte) []byte {
return common.LeftPadBytes(crypto.Ripemd160(in), 32)
}
const ecRecoverInputLength = 128
func ecrecoverFunc(in []byte) []byte {
in = common.RightPadBytes(in, 128)
// "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])
// Treat V as a 256bit integer
vbig := common.Bytes2Big(in[32:64])
v := byte(vbig.Uint64())
// tighter sig s values in homestead only apply to tx sigs
if !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 and normalized for libsecp256k1
vbignormal := new(big.Int).Sub(vbig, big.NewInt(27))
vnormal := byte(vbignormal.Uint64())
rsv := append(in[64:128], vnormal)
pubKey, err := crypto.Ecrecover(in[:32], rsv)
// 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)
}
func memCpy(in []byte) []byte {
return in
}
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