135 lines
4.6 KiB
Go
135 lines
4.6 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"crypto/sha256"
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"errors"
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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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"github.com/ethereum/go-ethereum/params"
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"golang.org/x/crypto/ripemd160"
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)
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var errBadPrecompileInput = errors.New("bad pre compile input")
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// Precompiled contract is the basic interface for native Go contracts. The implementation
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// requires a deterministic gas count based on the input size of the Run method of the
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// contract.
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type PrecompiledContract interface {
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RequiredGas(input []byte) uint64 // RequiredPrice calculates the contract gas use
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Run(input []byte) ([]byte, error) // Run runs the precompiled contract
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}
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// PrecompiledContracts contains the default set of ethereum contracts
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var PrecompiledContracts = map[common.Address]PrecompiledContract{
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common.BytesToAddress([]byte{1}): &ecrecover{},
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common.BytesToAddress([]byte{2}): &sha256hash{},
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common.BytesToAddress([]byte{3}): &ripemd160hash{},
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common.BytesToAddress([]byte{4}): &dataCopy{},
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}
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// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
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func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
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gas := p.RequiredGas(input)
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if contract.UseGas(gas) {
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return p.Run(input)
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} else {
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return nil, ErrOutOfGas
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}
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}
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// ECRECOVER implemented as a native contract
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type ecrecover struct{}
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func (c *ecrecover) RequiredGas(input []byte) uint64 {
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return params.EcrecoverGas
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}
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func (c *ecrecover) Run(in []byte) ([]byte, error) {
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const ecRecoverInputLength = 128
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in = common.RightPadBytes(in, ecRecoverInputLength)
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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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r := new(big.Int).SetBytes(in[64:96])
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s := new(big.Int).SetBytes(in[96:128])
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v := in[63] - 27
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// tighter sig s values in homestead only apply to tx sigs
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if !allZero(in[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
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return nil, nil
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}
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// v needs to be at the end for libsecp256k1
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pubKey, err := crypto.Ecrecover(in[:32], append(in[64:128], v))
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// make sure the public key is a valid one
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if err != nil {
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return nil, 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.Keccak256(pubKey[1:])[12:], 32), nil
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}
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// SHA256 implemented as a native contract
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type sha256hash struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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//
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// This method does not require any overflow checking as the input size gas costs
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// required for anything significant is so high it's impossible to pay for.
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func (c *sha256hash) RequiredGas(input []byte) uint64 {
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return uint64(len(input)+31)/32*params.Sha256WordGas + params.Sha256Gas
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}
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func (c *sha256hash) Run(in []byte) ([]byte, error) {
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h := sha256.Sum256(in)
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return h[:], nil
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}
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// RIPMED160 implemented as a native contract
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type ripemd160hash struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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//
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// This method does not require any overflow checking as the input size gas costs
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// required for anything significant is so high it's impossible to pay for.
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func (c *ripemd160hash) RequiredGas(input []byte) uint64 {
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return uint64(len(input)+31)/32*params.Ripemd160WordGas + params.Ripemd160Gas
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}
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func (c *ripemd160hash) Run(in []byte) ([]byte, error) {
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ripemd := ripemd160.New()
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ripemd.Write(in)
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return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
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}
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// data copy implemented as a native contract
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type dataCopy struct{}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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//
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// This method does not require any overflow checking as the input size gas costs
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// required for anything significant is so high it's impossible to pay for.
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func (c *dataCopy) RequiredGas(input []byte) uint64 {
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return uint64(len(input)+31)/32*params.IdentityWordGas + params.IdentityGas
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}
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func (c *dataCopy) Run(in []byte) ([]byte, error) {
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return in, nil
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}
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