[master-2.x] Fix Transaction verify (#2009)

* Fix transaction verification

* fix

Co-authored-by: Jin Qiao <jinqiao@neo.org>

neo.UnitTests/TestBlockchain.cs

@@ -52,6 +52,7 @@ public static NeoSystem InitializeMockNeoSystem()
  mockStore.Setup(p => p.GetContracts()).Returns(new TestDataCache<UInt160, ContractState>());
  mockStore.Setup(p => p.GetStorages()).Returns(new TestDataCache<StorageKey, StorageItem>());
  mockStore.Setup(p => p.GetHeaderHashList()).Returns(new TestDataCache<UInt32Wrapper, HeaderHashList>());
+ mockStore.Setup(p => p.GetStateRoots()).Returns(new TestDataCache<UInt32Wrapper, StateRootState>());
  mockStore.Setup(p => p.GetValidatorsCount()).Returns(new TestMetaDataCache<ValidatorsCountState>());
  mockStore.Setup(p => p.GetBlockHashIndex()).Returns(new TestMetaDataCache<HashIndexState>());
  mockStore.Setup(p => p.GetHeaderHashIndex()).Returns(new TestMetaDataCache<HashIndexState>());

neo/Network/P2P/Payloads/Transaction.cs

@@ -82,24 +82,26 @@ public virtual Fixed8 NetworkFee
  }
 
  private IReadOnlyDictionary<CoinReference, TransactionOutput> _references;
+ private bool hasCalculatedReferences = false;
  public IReadOnlyDictionary<CoinReference, TransactionOutput> References
  {
  get
  {
- if (_references == null)
+ if (!hasCalculatedReferences && _references == null)
  {
+ hasCalculatedReferences = true;
  Dictionary<CoinReference, TransactionOutput> dictionary = new Dictionary<CoinReference, TransactionOutput>();
  foreach (var group in Inputs.GroupBy(p => p.PrevHash))
  {
  Transaction tx = Blockchain.Singleton.Store.GetTransaction(group.Key);
  if (tx == null) return null;
- foreach (var reference in group.Select(p => new
+ foreach (var reference in group)
  {
- Input = p,
- Output = tx.Outputs[p.PrevIndex]
- }))
- {
- dictionary.Add(reference.Input, reference.Output);
+ if (reference.PrevIndex >= Outputs.Length)
+ {
+  return null;
+  }
+ dictionary.Add(reference, tx.Outputs[reference.PrevIndex]);
  }
  }
  _references = dictionary;