plugeth/core/vm/contracts.go

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// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
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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
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// 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
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// 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 (
"crypto/sha256"
"errors"
common: move big integer math to common/math (#3699) * common: remove CurrencyToString Move denomination values to params instead. * common: delete dead code * common: move big integer operations to common/math This commit consolidates all big integer operations into common/math and adds tests and documentation. There should be no change in semantics for BigPow, BigMin, BigMax, S256, U256, Exp and their behaviour is now locked in by tests. The BigD, BytesToBig and Bytes2Big functions don't provide additional value, all uses are replaced by new(big.Int).SetBytes(). BigToBytes is now called PaddedBigBytes, its minimum output size parameter is now specified as the number of bytes instead of bits. The single use of this function is in the EVM's MSTORE instruction. Big and String2Big are replaced by ParseBig, which is slightly stricter. It previously accepted leading zeros for hexadecimal inputs but treated decimal inputs as octal if a leading zero digit was present. ParseUint64 is used in places where String2Big was used to decode a uint64. The new functions MustParseBig and MustParseUint64 are now used in many places where parsing errors were previously ignored. * common: delete unused big integer variables * accounts/abi: replace uses of BytesToBig with use of encoding/binary * common: remove BytesToBig * common: remove Bytes2Big * common: remove BigTrue * cmd/utils: add BigFlag and use it for error-checked integer flags While here, remove environment variable processing for DirectoryFlag because we don't use it. * core: add missing error checks in genesis block parser * common: remove String2Big * cmd/evm: use utils.BigFlag * common/math: check for 256 bit overflow in ParseBig This is supposed to prevent silent overflow/truncation of values in the genesis block JSON. Without this check, a genesis block that set a balance larger than 256 bits would lead to weird behaviour in the VM. * cmd/utils: fixup import
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"math/big"
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"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/bn256"
"github.com/ethereum/go-ethereum/params"
"golang.org/x/crypto/ripemd160"
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)
// PrecompiledContract is the basic interface for native Go contracts. The implementation
// requires a deterministic gas count based on the input size of the Run method of the
// contract.
type PrecompiledContract interface {
RequiredGas(input []byte) uint64 // RequiredPrice calculates the contract gas use
Run(input []byte) ([]byte, error) // Run runs the precompiled contract
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}
// PrecompiledContractsHomestead contains the default set of pre-compiled Ethereum
// contracts used in the Frontier and Homestead releases.
var PrecompiledContractsHomestead = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256hash{},
common.BytesToAddress([]byte{3}): &ripemd160hash{},
common.BytesToAddress([]byte{4}): &dataCopy{},
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}
// PrecompiledContractsMetropolis contains the default set of pre-compiled Ethereum
// contracts used in the Metropolis release.
var PrecompiledContractsMetropolis = map[common.Address]PrecompiledContract{
common.BytesToAddress([]byte{1}): &ecrecover{},
common.BytesToAddress([]byte{2}): &sha256hash{},
common.BytesToAddress([]byte{3}): &ripemd160hash{},
common.BytesToAddress([]byte{4}): &dataCopy{},
common.BytesToAddress([]byte{5}): &bigModExp{},
common.BytesToAddress([]byte{6}): &bn256Add{},
common.BytesToAddress([]byte{7}): &bn256ScalarMul{},
common.BytesToAddress([]byte{8}): &bn256Pairing{},
}
// RunPrecompiledContract runs and evaluates the output of a precompiled contract.
func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
gas := p.RequiredGas(input)
if contract.UseGas(gas) {
return p.Run(input)
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}
return nil, ErrOutOfGas
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}
// ECRECOVER implemented as a native contract.
type ecrecover struct{}
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func (c *ecrecover) RequiredGas(input []byte) uint64 {
return params.EcrecoverGas
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}
func (c *ecrecover) Run(input []byte) ([]byte, error) {
const ecRecoverInputLength = 128
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input = common.RightPadBytes(input, ecRecoverInputLength)
// "input" is (hash, v, r, s), each 32 bytes
// but for ecrecover we want (r, s, v)
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r := new(big.Int).SetBytes(input[64:96])
s := new(big.Int).SetBytes(input[96:128])
v := input[63] - 27
// tighter sig s values input homestead only apply to tx sigs
if !allZero(input[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
return nil, nil
}
// v needs to be at the end for libsecp256k1
pubKey, err := crypto.Ecrecover(input[:32], append(input[64:128], v))
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// make sure the public key is a valid one
if err != nil {
return nil, nil
}
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// the first byte of pubkey is bitcoin heritage
return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
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}
// SHA256 implemented as a native contract.
type sha256hash struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *sha256hash) RequiredGas(input []byte) uint64 {
return uint64(len(input)+31)/32*params.Sha256PerWordGas + params.Sha256BaseGas
}
func (c *sha256hash) Run(input []byte) ([]byte, error) {
h := sha256.Sum256(input)
return h[:], nil
}
// RIPMED160 implemented as a native contract.
type ripemd160hash struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *ripemd160hash) RequiredGas(input []byte) uint64 {
return uint64(len(input)+31)/32*params.Ripemd160PerWordGas + params.Ripemd160BaseGas
}
func (c *ripemd160hash) Run(input []byte) ([]byte, error) {
ripemd := ripemd160.New()
ripemd.Write(input)
return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
}
// data copy implemented as a native contract.
type dataCopy struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
//
// This method does not require any overflow checking as the input size gas costs
// required for anything significant is so high it's impossible to pay for.
func (c *dataCopy) RequiredGas(input []byte) uint64 {
return uint64(len(input)+31)/32*params.IdentityPerWordGas + params.IdentityBaseGas
}
func (c *dataCopy) Run(in []byte) ([]byte, error) {
return in, nil
}
// bigModExp implements a native big integer exponential modular operation.
type bigModExp struct{}
var (
big1 = big.NewInt(1)
big4 = big.NewInt(4)
big8 = big.NewInt(8)
big16 = big.NewInt(16)
big32 = big.NewInt(32)
big64 = big.NewInt(64)
big96 = big.NewInt(96)
big480 = big.NewInt(480)
big1024 = big.NewInt(1024)
big3072 = big.NewInt(3072)
big199680 = big.NewInt(199680)
)
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bigModExp) RequiredGas(input []byte) uint64 {
var (
baseLen = new(big.Int).SetBytes(getData(input, 0, 32))
expLen = new(big.Int).SetBytes(getData(input, 32, 32))
modLen = new(big.Int).SetBytes(getData(input, 64, 32))
)
if len(input) > 96 {
input = input[96:]
} else {
input = input[:0]
}
// Retrieve the head 32 bytes of exp for the adjusted exponent length
var expHead *big.Int
if big.NewInt(int64(len(input))).Cmp(baseLen) <= 0 {
expHead = new(big.Int)
} else {
if expLen.Cmp(big32) > 0 {
expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), 32))
} else {
expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), expLen.Uint64()))
}
}
// Calculate the adjusted exponent length
var msb int
if bitlen := expHead.BitLen(); bitlen > 0 {
msb = bitlen - 1
}
adjExpLen := new(big.Int)
if expLen.Cmp(big32) > 0 {
adjExpLen.Sub(expLen, big32)
adjExpLen.Mul(big8, adjExpLen)
}
adjExpLen.Add(adjExpLen, big.NewInt(int64(msb)))
// Calculate the gas cost of the operation
gas := new(big.Int).Set(math.BigMax(modLen, baseLen))
switch {
case gas.Cmp(big64) <= 0:
gas.Mul(gas, gas)
case gas.Cmp(big1024) <= 0:
gas = new(big.Int).Add(
new(big.Int).Div(new(big.Int).Mul(gas, gas), big4),
new(big.Int).Sub(new(big.Int).Mul(big96, gas), big3072),
)
default:
gas = new(big.Int).Add(
new(big.Int).Div(new(big.Int).Mul(gas, gas), big16),
new(big.Int).Sub(new(big.Int).Mul(big480, gas), big199680),
)
}
gas.Mul(gas, math.BigMax(adjExpLen, big1))
gas.Div(gas, new(big.Int).SetUint64(params.ModExpQuadCoeffDiv))
if gas.BitLen() > 64 {
return math.MaxUint64
}
return gas.Uint64()
}
func (c *bigModExp) Run(input []byte) ([]byte, error) {
var (
baseLen = new(big.Int).SetBytes(getData(input, 0, 32)).Uint64()
expLen = new(big.Int).SetBytes(getData(input, 32, 32)).Uint64()
modLen = new(big.Int).SetBytes(getData(input, 64, 32)).Uint64()
)
if len(input) > 96 {
input = input[96:]
} else {
input = input[:0]
}
// Handle a special case when both the base and mod length is zero
if baseLen == 0 && modLen == 0 {
return []byte{}, nil
}
// Retrieve the operands and execute the exponentiation
var (
base = new(big.Int).SetBytes(getData(input, 0, baseLen))
exp = new(big.Int).SetBytes(getData(input, baseLen, expLen))
mod = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen))
)
if mod.BitLen() == 0 {
// Modulo 0 is undefined, return zero
return common.LeftPadBytes([]byte{}, int(modLen)), nil
}
return common.LeftPadBytes(base.Exp(base, exp, mod).Bytes(), int(modLen)), nil
}
var (
// errNotOnCurve is returned if a point being unmarshalled as a bn256 elliptic
// curve point is not on the curve.
errNotOnCurve = errors.New("point not on elliptic curve")
// errInvalidCurvePoint is returned if a point being unmarshalled as a bn256
// elliptic curve point is invalid.
errInvalidCurvePoint = errors.New("invalid elliptic curve point")
)
// newCurvePoint unmarshals a binary blob into a bn256 elliptic curve point,
// returning it, or an error if the point is invalid.
func newCurvePoint(blob []byte) (*bn256.G1, error) {
p, onCurve := new(bn256.G1).Unmarshal(blob)
if !onCurve {
return nil, errNotOnCurve
}
gx, gy, _, _ := p.CurvePoints()
if gx.Cmp(bn256.P) >= 0 || gy.Cmp(bn256.P) >= 0 {
return nil, errInvalidCurvePoint
}
return p, nil
}
// newTwistPoint unmarshals a binary blob into a bn256 elliptic curve point,
// returning it, or an error if the point is invalid.
func newTwistPoint(blob []byte) (*bn256.G2, error) {
p, onCurve := new(bn256.G2).Unmarshal(blob)
if !onCurve {
return nil, errNotOnCurve
}
x2, y2, _, _ := p.CurvePoints()
if x2.Real().Cmp(bn256.P) >= 0 || x2.Imag().Cmp(bn256.P) >= 0 ||
y2.Real().Cmp(bn256.P) >= 0 || y2.Imag().Cmp(bn256.P) >= 0 {
return nil, errInvalidCurvePoint
}
return p, nil
}
// bn256Add implements a native elliptic curve point addition.
type bn256Add struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256Add) RequiredGas(input []byte) uint64 {
return params.Bn256AddGas
}
func (c *bn256Add) Run(input []byte) ([]byte, error) {
x, err := newCurvePoint(getData(input, 0, 64))
if err != nil {
return nil, err
}
y, err := newCurvePoint(getData(input, 64, 64))
if err != nil {
return nil, err
}
res := new(bn256.G1)
res.Add(x, y)
return res.Marshal(), nil
}
// bn256ScalarMul implements a native elliptic curve scalar multiplication.
type bn256ScalarMul struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256ScalarMul) RequiredGas(input []byte) uint64 {
return params.Bn256ScalarMulGas
}
func (c *bn256ScalarMul) Run(input []byte) ([]byte, error) {
p, err := newCurvePoint(getData(input, 0, 64))
if err != nil {
return nil, err
}
res := new(bn256.G1)
res.ScalarMult(p, new(big.Int).SetBytes(getData(input, 64, 32)))
return res.Marshal(), nil
}
var (
// true32Byte is returned if the bn256 pairing check succeeds.
true32Byte = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
// false32Byte is returned if the bn256 pairing check fails.
false32Byte = make([]byte, 32)
// errBadPairingInput is returned if the bn256 pairing input is invalid.
errBadPairingInput = errors.New("bad elliptic curve pairing size")
)
// bn256Pairing implements a pairing pre-compile for the bn256 curve
type bn256Pairing struct{}
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bn256Pairing) RequiredGas(input []byte) uint64 {
return params.Bn256PairingBaseGas + uint64(len(input)/192)*params.Bn256PairingPerPointGas
}
func (c *bn256Pairing) Run(input []byte) ([]byte, error) {
// Handle some corner cases cheaply
if len(input)%192 > 0 {
return nil, errBadPairingInput
}
// Convert the input into a set of coordinates
var (
cs []*bn256.G1
ts []*bn256.G2
)
for i := 0; i < len(input); i += 192 {
c, err := newCurvePoint(input[i : i+64])
if err != nil {
return nil, err
}
t, err := newTwistPoint(input[i+64 : i+192])
if err != nil {
return nil, err
}
cs = append(cs, c)
ts = append(ts, t)
}
// Execute the pairing checks and return the results
if bn256.PairingCheck(cs, ts) {
return true32Byte, nil
}
return false32Byte, nil
}