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 }