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package vm
import (
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
)
type Address interface {
Call(in []byte) []byte
}
type PrecompiledAccount struct {
Gas func(l int) *big.Int
fn func(in []byte) []byte
}
func (self PrecompiledAccount) Call(in []byte) []byte {
return self.fn(in)
}
var Precompiled = PrecompiledContracts()
// XXX Could set directly. Testing requires resetting and setting of pre compiled contracts.
func PrecompiledContracts() map[string]*PrecompiledAccount {
return map[string]*PrecompiledAccount{
// ECRECOVER
string(common.LeftPadBytes([]byte{1}, 20)): &PrecompiledAccount{func(l int) *big.Int {
return GasEcrecover
}, ecrecoverFunc},
// SHA256
string(common.LeftPadBytes([]byte{2}, 20)): &PrecompiledAccount{func(l int) *big.Int {
n := big.NewInt(int64(l+31) / 32)
n.Mul(n, GasSha256Word)
return n.Add(n, GasSha256Base)
}, sha256Func},
// RIPEMD160
string(common.LeftPadBytes([]byte{3}, 20)): &PrecompiledAccount{func(l int) *big.Int {
n := big.NewInt(int64(l+31) / 32)
n.Mul(n, GasRipemdWord)
return n.Add(n, GasRipemdBase)
}, ripemd160Func},
string(common.LeftPadBytes([]byte{4}, 20)): &PrecompiledAccount{func(l int) *big.Int {
n := big.NewInt(int64(l+31) / 32)
n.Mul(n, GasIdentityWord)
return n.Add(n, GasIdentityBase)
}, 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" is (hash, v, r, s), each 32 bytes
// but for ecrecover we want (r, s, v)
if len(in) < ecRecoverInputLength {
return nil
}
// Treat V as a 256bit integer
v := new(big.Int).Sub(common.Bytes2Big(in[32:64]), big.NewInt(27))
// Ethereum requires V to be either 0 or 1 => (27 || 28)
if !(v.Cmp(Zero) == 0 || v.Cmp(One) == 0) {
return nil
}
// v needs to be moved to the end
rsv := append(in[64:128], byte(v.Uint64()))
pubKey := crypto.Ecrecover(in[:32], rsv)
// make sure the public key is a valid one
if pubKey == nil || len(pubKey) != 65 {
return nil
}
// the first byte of pubkey is bitcoin heritage
return common.LeftPadBytes(crypto.Sha3(pubKey[1:])[12:], 32)
}
func memCpy(in []byte) []byte {
return in
}
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