Consensus: finding the best way to create a history of block executions results

src/DBFTPlugin/Consensus/ConsensusService.OnMessage.cs

@@ -10,15 +10,14 @@
 
 using Akka.Actor;
 using Neo.Cryptography;
-using Neo.IO;
 using Neo.Ledger;
 using Neo.Network.P2P;
 using Neo.Network.P2P.Payloads;
 using Neo.SmartContract;
 using Neo.SmartContract.Native;
-using Neo.Wallets;
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 
 namespace Neo.Consensus
@@ -76,6 +75,12 @@ private void OnConsensusPayload(ExtensiblePayload payload)
 
  private void OnPrepareRequestReceived(ExtensiblePayload payload, PrepareRequest message)
  {
+ if (!File.Exists("prestatehash") || File.ReadAllText("prestatehash") != message.PreStateHash.ToString())
+ {
+ Log($"Invalid request: previous state hash does not match", LogLevel.Warning);
+ return;
+ }
+
  if (context.RequestSentOrReceived || context.NotAcceptingPayloadsDueToViewChanging) return;
  if (message.ValidatorIndex != context.Block.PrimaryIndex || message.ViewNumber != context.ViewNumber) return;
  if (message.Version != context.Block.Version || message.PrevHash != context.Block.PrevHash) return;

src/DBFTPlugin/DBFTPlugin.cs

@@ -8,10 +8,17 @@
 // Redistribution and use in source and binary forms with or without
 // modifications are permitted.
 
+using System.Collections.Generic;
+using System;
+using System.IO;
+using System.Security.Cryptography;
 using Akka.Actor;
 using Neo.ConsoleService;
+using System.Text.Json;
+using Neo.Ledger;
 using Neo.Network.P2P;
 using Neo.Network.P2P.Payloads;
+using Neo.Persistence;
 using Neo.Plugins;
 using Neo.Wallets;
 
@@ -30,6 +37,7 @@ public class DBFTPlugin : Plugin
  public DBFTPlugin()
  {
  RemoteNode.MessageReceived += RemoteNode_MessageReceived;
+ Blockchain.Committing += OnCommitting;
  }
 
  public DBFTPlugin(Settings settings) : this()
@@ -96,5 +104,18 @@ private bool RemoteNode_MessageReceived(NeoSystem system, Message message)
  }
  return true;
  }
+
+ private static void OnCommitting(NeoSystem system, Block block, DataCache snapshot, IReadOnlyList<Blockchain.ApplicationExecuted> applicationExecutedList)
+ {
+ var serializedData = JsonSerializer.SerializeToUtf8Bytes(applicationExecutedList);
+ var hash = ComputeSha256Hash(serializedData);
+ File.WriteAllText("prestatehash", hash);
+ }
+
+ private static string ComputeSha256Hash(byte[] rawData)
+ {
+ var bytes = SHA256.HashData(rawData);
+ return BitConverter.ToString(bytes).Replace("-", "").ToLower();
+ }
  }
 }

src/DBFTPlugin/Messages/PrepareRequest.cs

@@ -19,13 +19,17 @@ public class PrepareRequest : ConsensusMessage
  {
  public uint Version;
  public UInt256 PrevHash;
+ // The execution result hash of the previous block transactions
+ // since we do not need to update it or search it, no merkel tree is needed
+ public UInt256 PreStateHash;
  public ulong Timestamp;
  public ulong Nonce;
  public UInt256[] TransactionHashes;
 
  public override int Size => base.Size
  + sizeof(uint) //Version
  + UInt256.Length //PrevHash
+ + UInt256.Length //PreStateHash
  + sizeof(ulong) //Timestamp
  + sizeof(ulong) // Nonce
  + TransactionHashes.GetVarSize(); //TransactionHashes
@@ -37,6 +41,7 @@ public override void Deserialize(ref MemoryReader reader)
  base.Deserialize(ref reader);
  Version = reader.ReadUInt32();
  PrevHash = reader.ReadSerializable<UInt256>();
+ PreStateHash = reader.ReadSerializable<UInt256>();
  Timestamp = reader.ReadUInt64();
  Nonce = reader.ReadUInt64();
  TransactionHashes = reader.ReadSerializableArray<UInt256>(ushort.MaxValue);
@@ -55,6 +60,7 @@ public override void Serialize(BinaryWriter writer)
  base.Serialize(writer);
  writer.Write(Version);
  writer.Write(PrevHash);
+ writer.Write(PreStateHash);
  writer.Write(Timestamp);
  writer.Write(Nonce);
  writer.Write(TransactionHashes);