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legacy_withdrawal.go
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/
legacy_withdrawal.go
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package crossdomain
import (
"bytes"
"errors"
"fmt"
"math/big"
"github.com/sliceledger-blockchain/slice-ledger/op-bindings/bindings"
"github.com/sliceledger-blockchain/slice-ledger/op-bindings/predeploys"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/crypto"
)
// LegacyWithdrawal represents a pre bedrock upgrade withdrawal.
type LegacyWithdrawal struct {
// MessageSender is the caller of the message passer
MessageSender common.Address `json:"who"`
// XDomainTarget is the L1 target of the withdrawal message
XDomainTarget common.Address `json:"target"`
// XDomainSender is the L2 withdrawing account
XDomainSender common.Address `json:"sender"`
// XDomainData represents the calldata of the withdrawal message
XDomainData hexutil.Bytes `json:"data"`
// XDomainNonce represents the nonce of the withdrawal
XDomainNonce *big.Int `json:"nonce"`
}
var _ WithdrawalMessage = (*LegacyWithdrawal)(nil)
// NewLegacyWithdrawal will construct a LegacyWithdrawal
func NewLegacyWithdrawal(msgSender, target, sender common.Address, data []byte, nonce *big.Int) *LegacyWithdrawal {
return &LegacyWithdrawal{
MessageSender: msgSender,
XDomainTarget: target,
XDomainSender: sender,
XDomainData: data,
XDomainNonce: nonce,
}
}
// Encode will serialze the Withdrawal in the legacy format so that it
// is suitable for hashing. This assumes that the message is being withdrawn
// through the standard slice cross domain messaging system by hashing in
// the L2CrossDomainMessenger address.
func (w *LegacyWithdrawal) Encode() ([]byte, error) {
enc, err := EncodeCrossDomainMessageV0(w.XDomainTarget, w.XDomainSender, []byte(w.XDomainData), w.XDomainNonce)
if err != nil {
return nil, fmt.Errorf("cannot encode LegacyWithdrawal: %w", err)
}
out := make([]byte, len(enc)+len(predeploys.L2CrossDomainMessengerAddr.Bytes()))
copy(out, enc)
copy(out[len(enc):], predeploys.L2CrossDomainMessengerAddr.Bytes())
return out, nil
}
// Decode will decode a serialized LegacyWithdrawal. There is a known inconsistency
// where the decoded `msg.sender` is not authenticated. A round trip of encoding and
// decoding with a spoofed withdrawal will result in a different message being recovered.
func (w *LegacyWithdrawal) Decode(data []byte) error {
if len(data) < len(predeploys.L2CrossDomainMessengerAddr)+4 {
return fmt.Errorf("withdrawal data too short: %d", len(data))
}
selector := crypto.Keccak256([]byte("relayMessage(address,address,bytes,uint256)"))[0:4]
if !bytes.Equal(data[0:4], selector) {
return fmt.Errorf("invalid selector: 0x%x", data[0:4])
}
// This should be the L2CrossDomainMessenger address but is not guaranteed
// to be.
msgSender := data[len(data)-len(predeploys.L2CrossDomainMessengerAddr):]
raw := data[4 : len(data)-len(predeploys.L2CrossDomainMessengerAddr)]
args := abi.Arguments{
{Name: "target", Type: AddressType},
{Name: "sender", Type: AddressType},
{Name: "data", Type: BytesType},
{Name: "nonce", Type: Uint256Type},
}
decoded, err := args.Unpack(raw)
if err != nil {
return err
}
target, ok := decoded[0].(common.Address)
if !ok {
return errors.New("cannot abi decode target")
}
sender, ok := decoded[1].(common.Address)
if !ok {
return errors.New("cannot abi decode sender")
}
msgData, ok := decoded[2].([]byte)
if !ok {
return errors.New("cannot abi decode data")
}
nonce, ok := decoded[3].(*big.Int)
if !ok {
return errors.New("cannot abi decode nonce")
}
w.MessageSender = common.BytesToAddress(msgSender)
w.XDomainTarget = target
w.XDomainSender = sender
w.XDomainData = msgData
w.XDomainNonce = nonce
return nil
}
// Hash will compute the legacy style hash that is computed in the
// OVM_L2ToL1MessagePasser.
func (w *LegacyWithdrawal) Hash() (common.Hash, error) {
encoded, err := w.Encode()
if err != nil {
return common.Hash{}, fmt.Errorf("cannot hash LegacyWithdrawal: %w", err)
}
hash := crypto.Keccak256(encoded)
return common.BytesToHash(hash), nil
}
// StorageSlot will compute the storage slot that is set
// to true in the legacy L2ToL1MessagePasser.
func (w *LegacyWithdrawal) StorageSlot() (common.Hash, error) {
hash, err := w.Hash()
if err != nil {
return common.Hash{}, fmt.Errorf("cannot compute storage slot: %w", err)
}
preimage := make([]byte, 64)
copy(preimage, hash.Bytes())
slot := crypto.Keccak256(preimage)
return common.BytesToHash(slot), nil
}
// Value returns the ETH value associated with the withdrawal. Since
// ETH was represented as an ERC20 token before the Bedrock upgrade,
// the sender and calldata must be observed and the value must be parsed
// out if "finalizeETHWithdrawal" is the method.
func (w *LegacyWithdrawal) Value() (*big.Int, error) {
abi, err := bindings.L1StandardBridgeMetaData.GetAbi()
if err != nil {
return nil, err
}
value := new(big.Int)
// Parse the 4byte selector
method, err := abi.MethodById(w.XDomainData)
// If it is an unknown selector, there is no value
if err != nil {
return value, nil
}
isFromL2StandardBridge := w.XDomainSender == predeploys.L2StandardBridgeAddr
if isFromL2StandardBridge && method.Name == "finalizeETHWithdrawal" {
data, err := method.Inputs.Unpack(w.XDomainData[4:])
if err != nil {
return nil, err
}
// bounds check
if len(data) < 3 {
return nil, errors.New("not enough data")
}
var ok bool
value, ok = data[2].(*big.Int)
if !ok {
return nil, errors.New("not big.Int")
}
}
return value, nil
}
// CrossDomainMessage turns the LegacyWithdrawal into
// a CrossDomainMessage. LegacyWithdrawals do not have
// the concept of value or gaslimit, so set them to 0.
func (w *LegacyWithdrawal) CrossDomainMessage() *CrossDomainMessage {
return &CrossDomainMessage{
Nonce: w.XDomainNonce,
Sender: w.XDomainSender,
Target: w.XDomainTarget,
Value: new(big.Int),
GasLimit: new(big.Int),
Data: []byte(w.XDomainData),
}
}