Add ping/pong for updating node height (#673)

neo/Network/P2P/Payloads/PingPayload.cs

@@ -0,0 +1,44 @@
+using Neo.IO;
+using System;
+using System.IO;
+
+namespace Neo.Network.P2P.Payloads
+{
+    public class PingPayload : ISerializable
+    {
+        public uint LastBlockIndex;
+        public uint Timestamp;
+        public uint Nonce;
+
+        public int Size =>
+            sizeof(uint) +  //LastBlockIndex
+            sizeof(uint) +  //Timestamp
+            sizeof(uint);   //Nonce
+
+
+        public static PingPayload Create(uint height)
+        {
+            Random rand = new Random();
+            return new PingPayload
+            {
+                LastBlockIndex = height,
+                Timestamp = DateTime.UtcNow.ToTimestamp(),
+                Nonce = (uint)rand.Next()
+            };
+        }
+
+        void ISerializable.Deserialize(BinaryReader reader)
+        {
+            LastBlockIndex = reader.ReadUInt32();
+            Timestamp = reader.ReadUInt32();
+            Nonce = reader.ReadUInt32();
+        }
+
+        void ISerializable.Serialize(BinaryWriter writer)
+        {
+            writer.Write(LastBlockIndex);
+            writer.Write(Timestamp);
+            writer.Write(Nonce);
+        }
+    }
+}

neo/Network/P2P/ProtocolHandler.cs

@@ -18,8 +18,6 @@ namespace Neo.Network.P2P
 {
     internal class ProtocolHandler : UntypedActor
     {
-        public class SetVersion { public VersionPayload Version; }
-        public class SetVerack { }
         public class SetFilter { public BloomFilter Filter; }
 
         private readonly NeoSystem system;
@@ -95,6 +93,12 @@ protected override void OnReceive(object message)
                 case "mempool":
                     OnMemPoolMessageReceived();
                     break;
+                case "ping":
+                    OnPingMessageReceived(msg.GetPayload<PingPayload>());
+                    break;
+                case "pong":
+                    OnPongMessageReceived(msg.GetPayload<PingPayload>());
+                    break;
                 case "tx":
                     if (msg.Payload.Length <= Transaction.MaxTransactionSize)
                         OnInventoryReceived(msg.GetTransaction());
@@ -105,8 +109,6 @@ protected override void OnReceive(object message)
                 case "alert":
                 case "merkleblock":
                 case "notfound":
-                case "ping":
-                case "pong":
                 case "reject":
                 default:
                     //暂时忽略
@@ -272,16 +274,27 @@ private void OnMemPoolMessageReceived()
                 Context.Parent.Tell(Message.Create("inv", payload));
         }
 
+        private void OnPingMessageReceived(PingPayload payload)
+        {
+            Context.Parent.Tell(payload);
+            Context.Parent.Tell(Message.Create("pong", PingPayload.Create(Blockchain.Singleton.Height)));
+        }
+
+        private void OnPongMessageReceived(PingPayload payload)
+        {
+            Context.Parent.Tell(payload);
+        }
+
         private void OnVerackMessageReceived()
         {
             verack = true;
-            Context.Parent.Tell(new SetVerack());
+            Context.Parent.Tell("verack");
         }
 
         private void OnVersionMessageReceived(VersionPayload payload)
         {
             version = payload;
-            Context.Parent.Tell(new SetVersion { Version = payload });
+            Context.Parent.Tell(payload);
         }
 
         public static Props Props(NeoSystem system)

neo/Network/P2P/RemoteNode.cs

@@ -29,6 +29,7 @@ internal class Relay { public IInventory Inventory; }
         public IPEndPoint Listener => new IPEndPoint(Remote.Address, ListenerPort);
         public override int ListenerPort => Version?.Port ?? 0;
         public VersionPayload Version { get; private set; }
+        public uint LastBlockIndex { get; private set; }
 
         public RemoteNode(NeoSystem system, object connection, IPEndPoint remote, IPEndPoint local)
             : base(connection, remote, local)
@@ -63,6 +64,8 @@ private void EnqueueMessage(Message message)
                 case "getblocks":
                 case "getheaders":
                 case "mempool":
+                case "ping":
+                case "pong":
                     is_single = true;
                     break;
             }
@@ -114,18 +117,27 @@ protected override void OnReceive(object message)
                 case Relay relay:
                     OnRelay(relay.Inventory);
                     break;
-                case ProtocolHandler.SetVersion setVersion:
-                    OnSetVersion(setVersion.Version);
+                case VersionPayload payload:
+                    OnVersionPayload(payload);
                     break;
-                case ProtocolHandler.SetVerack _:
-                    OnSetVerack();
+                case "verack":
+                    OnVerack();
                     break;
                 case ProtocolHandler.SetFilter setFilter:
                     OnSetFilter(setFilter.Filter);
                     break;
+                case PingPayload payload:
+                    OnPingPayload(payload);
+                    break;
             }
         }
 
+        private void OnPingPayload(PingPayload payload)
+        {
+            if (payload.LastBlockIndex > LastBlockIndex)
+                LastBlockIndex = payload.LastBlockIndex;
+        }
+
         private void OnRelay(IInventory inventory)
         {
             if (Version?.Relay != true) return;
@@ -153,16 +165,17 @@ private void OnSetFilter(BloomFilter filter)
             bloom_filter = filter;
         }
 
-        private void OnSetVerack()
+        private void OnVerack()
         {
             verack = true;
             system.TaskManager.Tell(new TaskManager.Register { Version = Version });
             CheckMessageQueue();
         }
 
-        private void OnSetVersion(VersionPayload version)
+        private void OnVersionPayload(VersionPayload version)
         {
             this.Version = version;
+            this.LastBlockIndex = Version.StartHeight;
             if (version.Nonce == LocalNode.Nonce)
             {
                 Disconnect(true);