1 files changed, 497 insertions, 0 deletions
diff --git a/core/vm/contracts.go b/core/vm/contracts.go
new file mode 100644
index 0000000..54eab4e
--- /dev/null
+++ b/core/vm/contracts.go
@@ -0,0 +1,497 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// 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,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// 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/>.
+
+package vm
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"errors"
+	"math/big"
+
+	"github.com/ava-labs/coreth/params"
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/common/math"
+	"github.com/ava-labs/go-ethereum/crypto"
+	"github.com/ava-labs/go-ethereum/crypto/blake2b"
+	"github.com/ava-labs/go-ethereum/crypto/bn256"
+	"golang.org/x/crypto/ripemd160"
+)
+
+// 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
+}
+
+// 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{},
+}
+
+// PrecompiledContractsByzantium contains the default set of pre-compiled Ethereum
+// contracts used in the Byzantium release.
+var PrecompiledContractsByzantium = 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}): &bn256AddByzantium{},
+	common.BytesToAddress([]byte{7}): &bn256ScalarMulByzantium{},
+	common.BytesToAddress([]byte{8}): &bn256PairingByzantium{},
+}
+
+// PrecompiledContractsIstanbul contains the default set of pre-compiled Ethereum
+// contracts used in the Istanbul release.
+var PrecompiledContractsIstanbul = 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}): &bn256AddIstanbul{},
+	common.BytesToAddress([]byte{7}): &bn256ScalarMulIstanbul{},
+	common.BytesToAddress([]byte{8}): &bn256PairingIstanbul{},
+	common.BytesToAddress([]byte{9}): &blake2F{},
+}
+
+// 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)
+	}
+	return nil, ErrOutOfGas
+}
+
+// ECRECOVER implemented as a native contract.
+type ecrecover struct{}
+
+func (c *ecrecover) RequiredGas(input []byte) uint64 {
+	return params.EcrecoverGas
+}
+
+func (c *ecrecover) Run(input []byte) ([]byte, error) {
+	const ecRecoverInputLength = 128
+
+	input = common.RightPadBytes(input, ecRecoverInputLength)
+	// "input" is (hash, v, r, s), each 32 bytes
+	// but for ecrecover we want (r, s, v)
+
+	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))
+	// make sure the public key is a valid one
+	if err != nil {
+		return nil, nil
+	}
+
+	// the first byte of pubkey is bitcoin heritage
+	return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
+}
+
+// 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
+}
+
+// RIPEMD160 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
+}
+
+// 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 := new(bn256.G1)
+	if _, err := p.Unmarshal(blob); err != nil {
+		return nil, err
+	}
+	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 := new(bn256.G2)
+	if _, err := p.Unmarshal(blob); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+// runBn256Add implements the Bn256Add precompile, referenced by both
+// Byzantium and Istanbul operations.
+func runBn256Add(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
+}
+
+// bn256Add implements a native elliptic curve point addition conforming to
+// Istanbul consensus rules.
+type bn256AddIstanbul struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256AddIstanbul) RequiredGas(input []byte) uint64 {
+	return params.Bn256AddGasIstanbul
+}
+
+func (c *bn256AddIstanbul) Run(input []byte) ([]byte, error) {
+	return runBn256Add(input)
+}
+
+// bn256AddByzantium implements a native elliptic curve point addition
+// conforming to Byzantium consensus rules.
+type bn256AddByzantium struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256AddByzantium) RequiredGas(input []byte) uint64 {
+	return params.Bn256AddGasByzantium
+}
+
+func (c *bn256AddByzantium) Run(input []byte) ([]byte, error) {
+	return runBn256Add(input)
+}
+
+// runBn256ScalarMul implements the Bn256ScalarMul precompile, referenced by
+// both Byzantium and Istanbul operations.
+func runBn256ScalarMul(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
+}
+
+// bn256ScalarMulIstanbul implements a native elliptic curve scalar
+// multiplication conforming to Istanbul consensus rules.
+type bn256ScalarMulIstanbul struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256ScalarMulIstanbul) RequiredGas(input []byte) uint64 {
+	return params.Bn256ScalarMulGasIstanbul
+}
+
+func (c *bn256ScalarMulIstanbul) Run(input []byte) ([]byte, error) {
+	return runBn256ScalarMul(input)
+}
+
+// bn256ScalarMulByzantium implements a native elliptic curve scalar
+// multiplication conforming to Byzantium consensus rules.
+type bn256ScalarMulByzantium struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256ScalarMulByzantium) RequiredGas(input []byte) uint64 {
+	return params.Bn256ScalarMulGasByzantium
+}
+
+func (c *bn256ScalarMulByzantium) Run(input []byte) ([]byte, error) {
+	return runBn256ScalarMul(input)
+}
+
+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")
+)
+
+// runBn256Pairing implements the Bn256Pairing precompile, referenced by both
+// Byzantium and Istanbul operations.
+func runBn256Pairing(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
+}
+
+// bn256PairingIstanbul implements a pairing pre-compile for the bn256 curve
+// conforming to Istanbul consensus rules.
+type bn256PairingIstanbul struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256PairingIstanbul) RequiredGas(input []byte) uint64 {
+	return params.Bn256PairingBaseGasIstanbul + uint64(len(input)/192)*params.Bn256PairingPerPointGasIstanbul
+}
+
+func (c *bn256PairingIstanbul) Run(input []byte) ([]byte, error) {
+	return runBn256Pairing(input)
+}
+
+// bn256PairingByzantium implements a pairing pre-compile for the bn256 curve
+// conforming to Byzantium consensus rules.
+type bn256PairingByzantium struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256PairingByzantium) RequiredGas(input []byte) uint64 {
+	return params.Bn256PairingBaseGasByzantium + uint64(len(input)/192)*params.Bn256PairingPerPointGasByzantium
+}
+
+func (c *bn256PairingByzantium) Run(input []byte) ([]byte, error) {
+	return runBn256Pairing(input)
+}
+
+type blake2F struct{}
+
+func (c *blake2F) RequiredGas(input []byte) uint64 {
+	// If the input is malformed, we can't calculate the gas, return 0 and let the
+	// actual call choke and fault.
+	if len(input) != blake2FInputLength {
+		return 0
+	}
+	return uint64(binary.BigEndian.Uint32(input[0:4]))
+}
+
+const (
+	blake2FInputLength        = 213
+	blake2FFinalBlockBytes    = byte(1)
+	blake2FNonFinalBlockBytes = byte(0)
+)
+
+var (
+	errBlake2FInvalidInputLength = errors.New("invalid input length")
+	errBlake2FInvalidFinalFlag   = errors.New("invalid final flag")
+)
+
+func (c *blake2F) Run(input []byte) ([]byte, error) {
+	// Make sure the input is valid (correct lenth and final flag)
+	if len(input) != blake2FInputLength {
+		return nil, errBlake2FInvalidInputLength
+	}
+	if input[212] != blake2FNonFinalBlockBytes && input[212] != blake2FFinalBlockBytes {
+		return nil, errBlake2FInvalidFinalFlag
+	}
+	// Parse the input into the Blake2b call parameters
+	var (
+		rounds = binary.BigEndian.Uint32(input[0:4])
+		final  = (input[212] == blake2FFinalBlockBytes)
+
+		h [8]uint64
+		m [16]uint64
+		t [2]uint64
+	)
+	for i := 0; i < 8; i++ {
+		offset := 4 + i*8
+		h[i] = binary.LittleEndian.Uint64(input[offset : offset+8])
+	}
+	for i := 0; i < 16; i++ {
+		offset := 68 + i*8
+		m[i] = binary.LittleEndian.Uint64(input[offset : offset+8])
+	}
+	t[0] = binary.LittleEndian.Uint64(input[196:204])
+	t[1] = binary.LittleEndian.Uint64(input[204:212])
+
+	// Execute the compression function, extract and return the result
+	blake2b.F(&h, m, t, final, rounds)
+
+	output := make([]byte, 64)
+	for i := 0; i < 8; i++ {
+		offset := i * 8
+		binary.LittleEndian.PutUint64(output[offset:offset+8], h[i])
+	}
+	return output, nil
+}