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// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
package evm
import (
"fmt"
"math/big"
"github.com/ava-labs/coreth/core/state"
"github.com/ava-labs/go-ethereum/log"
"github.com/ava-labs/avalanchego/chains/atomic"
"github.com/ava-labs/avalanchego/database"
"github.com/ava-labs/avalanchego/ids"
"github.com/ava-labs/avalanchego/snow"
"github.com/ava-labs/avalanchego/utils/crypto"
safemath "github.com/ava-labs/avalanchego/utils/math"
"github.com/ava-labs/avalanchego/vms/components/avax"
"github.com/ava-labs/avalanchego/vms/secp256k1fx"
)
// UnsignedExportTx is an unsigned ExportTx
type UnsignedExportTx struct {
avax.Metadata
// true iff this transaction has already passed syntactic verification
syntacticallyVerified bool
// ID of the network on which this tx was issued
NetworkID uint32 `serialize:"true" json:"networkID"`
// ID of this blockchain.
BlockchainID ids.ID `serialize:"true" json:"blockchainID"`
// Which chain to send the funds to
DestinationChain ids.ID `serialize:"true" json:"destinationChain"`
// Inputs
Ins []EVMInput `serialize:"true" json:"inputs"`
// Outputs that are exported to the chain
ExportedOutputs []*avax.TransferableOutput `serialize:"true" json:"exportedOutputs"`
}
// InputUTXOs returns an empty set
func (tx *UnsignedExportTx) InputUTXOs() ids.Set { return ids.Set{} }
// Verify this transaction is well-formed
func (tx *UnsignedExportTx) Verify(
avmID ids.ID,
ctx *snow.Context,
feeAmount uint64,
feeAssetID ids.ID,
) error {
switch {
case tx == nil:
return errNilTx
case tx.syntacticallyVerified: // already passed syntactic verification
return nil
case tx.DestinationChain.IsZero():
return errWrongChainID
case !tx.DestinationChain.Equals(avmID):
return errWrongChainID
case len(tx.ExportedOutputs) == 0:
return errNoExportOutputs
case tx.NetworkID != ctx.NetworkID:
return errWrongNetworkID
case !ctx.ChainID.Equals(tx.BlockchainID):
return errWrongBlockchainID
}
for _, in := range tx.Ins {
if err := in.Verify(); err != nil {
return err
}
}
for _, out := range tx.ExportedOutputs {
if err := out.Verify(); err != nil {
return err
}
}
if !avax.IsSortedTransferableOutputs(tx.ExportedOutputs, Codec) {
return errOutputsNotSorted
}
tx.syntacticallyVerified = true
return nil
}
// SemanticVerify this transaction is valid.
func (tx *UnsignedExportTx) SemanticVerify(
vm *VM,
stx *Tx,
) TxError {
if err := tx.Verify(vm.ctx.XChainID, vm.ctx, vm.txFee, vm.ctx.AVAXAssetID); err != nil {
return permError{err}
}
f := crypto.FactorySECP256K1R{}
for i, cred := range stx.Creds {
if err := cred.Verify(); err != nil {
return permError{err}
}
pubKey, err := f.RecoverPublicKey(tx.UnsignedBytes(), cred.(*secp256k1fx.Credential).Sigs[0][:])
if err != nil {
return permError{err}
}
if tx.Ins[i].Address != PublicKeyToEthAddress(pubKey) {
return permError{errPublicKeySignatureMismatch}
}
}
// do flow-checking
fc := avax.NewFlowChecker()
fc.Produce(vm.ctx.AVAXAssetID, vm.txFee)
for _, out := range tx.ExportedOutputs {
fc.Produce(out.AssetID(), out.Output().Amount())
}
for _, in := range tx.Ins {
fc.Consume(vm.ctx.AVAXAssetID, in.Amount)
}
if err := fc.Verify(); err != nil {
return permError{err}
}
// TODO: verify UTXO outputs via gRPC
return nil
}
// Accept this transaction.
func (tx *UnsignedExportTx) Accept(ctx *snow.Context, _ database.Batch) error {
txID := tx.ID()
elems := make([]*atomic.Element, len(tx.ExportedOutputs))
for i, out := range tx.ExportedOutputs {
utxo := &avax.UTXO{
UTXOID: avax.UTXOID{
TxID: txID,
OutputIndex: uint32(i),
},
Asset: avax.Asset{ID: out.AssetID()},
Out: out.Out,
}
utxoBytes, err := Codec.Marshal(utxo)
if err != nil {
return err
}
elem := &atomic.Element{
Key: utxo.InputID().Bytes(),
Value: utxoBytes,
}
if out, ok := utxo.Out.(avax.Addressable); ok {
elem.Traits = out.Addresses()
}
elems[i] = elem
}
return ctx.SharedMemory.Put(tx.DestinationChain, elems)
}
// Create a new transaction
func (vm *VM) newExportTx(
amount uint64, // Amount of tokens to export
chainID ids.ID, // Chain to send the UTXOs to
to ids.ShortID, // Address of chain recipient
keys []*crypto.PrivateKeySECP256K1R, // Pay the fee and provide the tokens
) (*Tx, error) {
if !vm.ctx.XChainID.Equals(chainID) {
return nil, errWrongChainID
}
toBurn, err := safemath.Add64(amount, vm.txFee)
if err != nil {
return nil, errOverflowExport
}
ins, signers, err := vm.GetSpendableCanonical(keys, toBurn)
if err != nil {
return nil, fmt.Errorf("couldn't generate tx inputs/outputs: %w", err)
}
// Create the transaction
utx := &UnsignedExportTx{
NetworkID: vm.ctx.NetworkID,
BlockchainID: vm.ctx.ChainID,
DestinationChain: chainID,
Ins: ins,
ExportedOutputs: []*avax.TransferableOutput{{ // Exported to X-Chain
Asset: avax.Asset{ID: vm.ctx.AVAXAssetID},
Out: &secp256k1fx.TransferOutput{
Amt: amount,
OutputOwners: secp256k1fx.OutputOwners{
Locktime: 0,
Threshold: 1,
Addrs: []ids.ShortID{to},
},
},
}},
}
tx := &Tx{UnsignedTx: utx}
if err := tx.Sign(vm.codec, signers); err != nil {
return nil, err
}
return tx, utx.Verify(vm.ctx.XChainID, vm.ctx, vm.txFee, vm.ctx.AVAXAssetID)
}
func (tx *UnsignedExportTx) EVMStateTransfer(state *state.StateDB) error {
for _, from := range tx.Ins {
log.Info("consume", "in", from.Address, "amount", from.Amount, "nonce", from.Nonce, "nonce0", state.GetNonce(from.Address))
amount := new(big.Int).Mul(
new(big.Int).SetUint64(from.Amount), x2cRate)
if state.GetBalance(from.Address).Cmp(amount) < 0 {
return errInsufficientFunds
}
state.SubBalance(from.Address, amount)
if state.GetNonce(from.Address) != from.Nonce {
return errInvalidNonce
}
state.SetNonce(from.Address, from.Nonce+1)
}
return nil
}
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