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94 lines
2.3 KiB
94 lines
2.3 KiB
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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)
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type Address interface {
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Call(in []byte) []byte
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}
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type PrecompiledAccount struct {
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Gas func(l int) *big.Int
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fn func(in []byte) []byte
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}
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func (self PrecompiledAccount) Call(in []byte) []byte {
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return self.fn(in)
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}
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var Precompiled = PrecompiledContracts()
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// XXX Could set directly. Testing requires resetting and setting of pre compiled contracts.
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func PrecompiledContracts() map[string]*PrecompiledAccount {
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return map[string]*PrecompiledAccount{
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// ECRECOVER
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string(common.LeftPadBytes([]byte{1}, 20)): &PrecompiledAccount{func(l int) *big.Int {
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return GasEcrecover
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}, ecrecoverFunc},
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// SHA256
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string(common.LeftPadBytes([]byte{2}, 20)): &PrecompiledAccount{func(l int) *big.Int {
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n := big.NewInt(int64(l+31) / 32)
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n.Mul(n, GasSha256Word)
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return n.Add(n, GasSha256Base)
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}, sha256Func},
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// RIPEMD160
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string(common.LeftPadBytes([]byte{3}, 20)): &PrecompiledAccount{func(l int) *big.Int {
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n := big.NewInt(int64(l+31) / 32)
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n.Mul(n, GasRipemdWord)
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return n.Add(n, GasRipemdBase)
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}, ripemd160Func},
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string(common.LeftPadBytes([]byte{4}, 20)): &PrecompiledAccount{func(l int) *big.Int {
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n := big.NewInt(int64(l+31) / 32)
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n.Mul(n, GasIdentityWord)
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return n.Add(n, GasIdentityBase)
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}, memCpy},
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}
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}
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func sha256Func(in []byte) []byte {
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return crypto.Sha256(in)
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}
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func ripemd160Func(in []byte) []byte {
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return common.LeftPadBytes(crypto.Ripemd160(in), 32)
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}
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const ecRecoverInputLength = 128
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func ecrecoverFunc(in []byte) []byte {
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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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if len(in) < ecRecoverInputLength {
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return nil
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}
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// Treat V as a 256bit integer
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v := new(big.Int).Sub(common.Bytes2Big(in[32:64]), big.NewInt(27))
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// Ethereum requires V to be either 0 or 1 => (27 || 28)
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if !(v.Cmp(Zero) == 0 || v.Cmp(One) == 0) {
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return nil
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}
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// v needs to be moved to the end
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rsv := append(in[64:128], byte(v.Uint64()))
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pubKey := crypto.Ecrecover(in[:32], rsv)
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// make sure the public key is a valid one
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if pubKey == nil || len(pubKey) != 65 {
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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.Sha3(pubKey[1:])[12:], 32)
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}
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func memCpy(in []byte) []byte {
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return in
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}
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