github.com/avence12/go-ethereum@v1.5.10-0.20170320123548-1dfd65f6d047/core/vm/contracts.go (about) 1 // Copyright 2014 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package vm 18 19 import ( 20 "crypto/sha256" 21 "math/big" 22 23 "github.com/ethereum/go-ethereum/common" 24 "github.com/ethereum/go-ethereum/crypto" 25 "github.com/ethereum/go-ethereum/log" 26 "github.com/ethereum/go-ethereum/params" 27 "golang.org/x/crypto/ripemd160" 28 ) 29 30 // Precompiled contract is the basic interface for native Go contracts. The implementation 31 // requires a deterministic gas count based on the input size of the Run method of the 32 // contract. 33 type PrecompiledContract interface { 34 RequiredGas(inputSize int) uint64 // RequiredPrice calculates the contract gas use 35 Run(input []byte) []byte // Run runs the precompiled contract 36 } 37 38 // Precompiled contains the default set of ethereum contracts 39 var PrecompiledContracts = map[common.Address]PrecompiledContract{ 40 common.BytesToAddress([]byte{1}): &ecrecover{}, 41 common.BytesToAddress([]byte{2}): &sha256hash{}, 42 common.BytesToAddress([]byte{3}): &ripemd160hash{}, 43 common.BytesToAddress([]byte{4}): &dataCopy{}, 44 } 45 46 // RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go 47 func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) { 48 gas := p.RequiredGas(len(input)) 49 if contract.UseGas(gas) { 50 ret = p.Run(input) 51 52 return ret, nil 53 } else { 54 return nil, ErrOutOfGas 55 } 56 } 57 58 // ECRECOVER implemented as a native contract 59 type ecrecover struct{} 60 61 func (c *ecrecover) RequiredGas(inputSize int) uint64 { 62 return params.EcrecoverGas 63 } 64 65 func (c *ecrecover) Run(in []byte) []byte { 66 const ecRecoverInputLength = 128 67 68 in = common.RightPadBytes(in, ecRecoverInputLength) 69 // "in" is (hash, v, r, s), each 32 bytes 70 // but for ecrecover we want (r, s, v) 71 72 r := new(big.Int).SetBytes(in[64:96]) 73 s := new(big.Int).SetBytes(in[96:128]) 74 v := in[63] - 27 75 76 // tighter sig s values in homestead only apply to tx sigs 77 if !allZero(in[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) { 78 log.Trace("ECRECOVER error: v, r or s value invalid") 79 return nil 80 } 81 // v needs to be at the end for libsecp256k1 82 pubKey, err := crypto.Ecrecover(in[:32], append(in[64:128], v)) 83 // make sure the public key is a valid one 84 if err != nil { 85 log.Trace("ECRECOVER failed", "err", err) 86 return nil 87 } 88 89 // the first byte of pubkey is bitcoin heritage 90 return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32) 91 } 92 93 // SHA256 implemented as a native contract 94 type sha256hash struct{} 95 96 // RequiredGas returns the gas required to execute the pre-compiled contract. 97 // 98 // This method does not require any overflow checking as the input size gas costs 99 // required for anything significant is so high it's impossible to pay for. 100 func (c *sha256hash) RequiredGas(inputSize int) uint64 { 101 return uint64(inputSize+31)/32*params.Sha256WordGas + params.Sha256Gas 102 } 103 func (c *sha256hash) Run(in []byte) []byte { 104 h := sha256.Sum256(in) 105 return h[:] 106 } 107 108 // RIPMED160 implemented as a native contract 109 type ripemd160hash struct{} 110 111 // RequiredGas returns the gas required to execute the pre-compiled contract. 112 // 113 // This method does not require any overflow checking as the input size gas costs 114 // required for anything significant is so high it's impossible to pay for. 115 func (c *ripemd160hash) RequiredGas(inputSize int) uint64 { 116 return uint64(inputSize+31)/32*params.Ripemd160WordGas + params.Ripemd160Gas 117 } 118 func (c *ripemd160hash) Run(in []byte) []byte { 119 ripemd := ripemd160.New() 120 ripemd.Write(in) 121 return common.LeftPadBytes(ripemd.Sum(nil), 32) 122 } 123 124 // data copy implemented as a native contract 125 type dataCopy struct{} 126 127 // RequiredGas returns the gas required to execute the pre-compiled contract. 128 // 129 // This method does not require any overflow checking as the input size gas costs 130 // required for anything significant is so high it's impossible to pay for. 131 func (c *dataCopy) RequiredGas(inputSize int) uint64 { 132 return uint64(inputSize+31)/32*params.IdentityWordGas + params.IdentityGas 133 } 134 func (c *dataCopy) Run(in []byte) []byte { 135 return in 136 }