From 6cc9d3c61ee803f37cbc6e65799797c0dc51e9e5 Mon Sep 17 00:00:00 2001
From: Aaron Buchwald <aaron.buchwald56@gmail.com>
Date: Wed, 23 Sep 2020 01:35:28 -0400
Subject: Sort evm outputs of import tx

---
 plugin/evm/import_tx.go | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

(limited to 'plugin/evm/import_tx.go')

diff --git a/plugin/evm/import_tx.go b/plugin/evm/import_tx.go
index 0b0d348..4d7f219 100644
--- a/plugin/evm/import_tx.go
+++ b/plugin/evm/import_tx.go
@@ -75,6 +75,9 @@ func (tx *UnsignedImportTx) Verify(
 			return err
 		}
 	}
+	if !IsSortedAndUniqueEVMOutputs(tx.Outs) {
+		return errExportOutputsNotSortedAndUnique
+	}
 
 	for _, in := range tx.ImportedInputs {
 		if err := in.Verify(); err != nil {
@@ -127,15 +130,6 @@ func (tx *UnsignedImportTx) SemanticVerify(
 		return tempError{err}
 	}
 
-	utxos := make([]*avax.UTXO, len(tx.ImportedInputs))
-	for i, utxoBytes := range allUTXOBytes {
-		utxo := &avax.UTXO{}
-		if err := vm.codec.Unmarshal(utxoBytes, utxo); err != nil {
-			return tempError{err}
-		}
-		utxos[i] = utxo
-	}
-
 	for i, in := range tx.ImportedInputs {
 		utxoBytes := allUTXOBytes[i]
 
@@ -173,7 +167,7 @@ func (tx *UnsignedImportTx) Accept(ctx *snow.Context, _ database.Batch) error {
 	return ctx.SharedMemory.Remove(tx.SourceChain, utxoIDs)
 }
 
-// Create a new transaction
+// newImportTx returns a new ImportTx
 func (vm *VM) newImportTx(
 	chainID ids.ID, // chain to import from
 	to common.Address, // Address of recipient
@@ -240,20 +234,23 @@ func (vm *VM) newImportTx(
 	//	})
 	//}
 
-	// non-AVAX asset outputs
-	for aidKey, amount := range importedAmount {
-		aid := ids.NewID(aidKey)
-		//if aid.Equals(vm.ctx.AVAXAssetID) || amount == 0 {
+	// This will create unique outputs (in the context of sorting)
+	// since each output will have a unique assetID
+	for assetKey, amount := range importedAmount {
+		assetID := ids.NewID(assetKey)
+		//if assetID.Equals(vm.ctx.AVAXAssetID) || amount == 0 {
 		if amount == 0 {
 			continue
 		}
 		outs = append(outs, EVMOutput{
 			Address: to,
 			Amount:  amount,
-			AssetID: aid,
+			AssetID: assetID,
 		})
 	}
 
+	SortEVMOutputs(outs)
+
 	// Create the transaction
 	utx := &UnsignedImportTx{
 		NetworkID:      vm.ctx.NetworkID,
@@ -269,6 +266,8 @@ func (vm *VM) newImportTx(
 	return tx, utx.Verify(vm.ctx.XChainID, vm.ctx, vm.txFee, vm.ctx.AVAXAssetID)
 }
 
+// EVMStateTransfer performs the state transfer to increase the balances of
+// accounts accordingly with the imported EVMOutputs
 func (tx *UnsignedImportTx) EVMStateTransfer(vm *VM, state *state.StateDB) error {
 	for _, to := range tx.Outs {
 		log.Info("crosschain X->C", "addr", to.Address, "amount", to.Amount)
-- 
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