fix sendblocks spam; fix faucet crash

Discreet/Network/Handler.cs

@@ -101,6 +101,9 @@ public class Handler
         private ConcurrentDictionary<IPEndPoint, HashSet<InventoryVectorRef>> NeededInventory = new();
         private ConcurrentDictionary<InventoryVectorRef, (long, long)> InventoryTimeouts = new(Environment.ProcessorCount, 25000, new InventoryEqualityComparer());
 
+        private Dictionary<Cipher.SHA256, long> cachedSendBlocks = new(new Cipher.SHA256EqualityComparer());
+        private long cachedSendBlocksIndex = 0;
+
         public async Task NeededInventoryStart(CancellationToken token)
         {
             while (!token.IsCancellationRequested)
@@ -1315,6 +1318,17 @@ public async Task HandleSendBlock(SendBlockPacket p, Peerbloom.Connection conn,
             }
         }
 
+        private Cipher.SHA256 CreateSendBlocksHash(SendBlocksPacket p)
+        {
+            byte[] dat = new byte[32 * p.Blocks.Length];
+            for (int i = 0; i < p.Blocks.Length; i++)
+            {
+                Array.Copy(p.Blocks[i].Header.BlockHash.Bytes, 0, dat, 32 * i, 32);
+            }
+
+            return new Cipher.SHA256(System.Security.Cryptography.SHA256.HashData(dat), false);
+        }
+
         public async Task HandleSendBlocks(SendBlocksPacket p, Peerbloom.Connection conn)
         {
             // ensure blocks are sorted
@@ -1344,6 +1358,26 @@ public async Task HandleSendBlocks(SendBlocksPacket p, Peerbloom.Connection conn
                 await HandleSendBlock(new SendBlockPacket { Block = block }, conn, false);
             }
 
+            var cachedSendBlocksHash = CreateSendBlocksHash(p);
+
+            // check against cachedSendBlocks rule for propagation
+            lock (cachedSendBlocks)
+            {
+                if (cachedSendBlocks.ContainsKey(cachedSendBlocksHash))
+                {
+                    // don't propagate, we've seen this
+                    return;
+                }
+
+                cachedSendBlocks[cachedSendBlocksHash] = cachedSendBlocksIndex;
+                cachedSendBlocksIndex++;
+                if (cachedSendBlocks.Count > 100)
+                {
+                    var vmin = cachedSendBlocks.MinBy(x => x.Value);
+                    cachedSendBlocks.Remove(vmin.Key);
+                }
+            }
+
             if (propagate.Any()) Peerbloom.Network.GetNetwork().Broadcast(new Packet(PacketType.SENDBLOCKS, p));
         }
 
@@ -1401,7 +1435,7 @@ public async Task HandleBlocks(BlocksPacket p, Peerbloom.Connection conn)
 
                 if (BlockBuffer.Instance.BlockExists(p.Blocks[0].Header.BlockHash))
                 {
-                    Daemon.Logger.Error("HandleBlocks: queried peer returned an existing block; ignoring");
+                    Daemon.Logger.Error("HandleBlocks: queried peer returned an existing block; ignoring", verbose: 3);
                 }
                 else
                 {

Discreet/Wallets/Services/WalletFundsService.cs

@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Data;
 using System.Diagnostics;
+using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -61,13 +62,21 @@ public virtual async Task StartFundsScanAsync(CancellationToken token = default)
                 State = ServiceState.SYNCED;
                 while (!token.IsCancellationRequested)
                 {
-                    var chainHeight = view.GetChainHeight();
-                    if (lastSeenHeight < chainHeight)
+                    try
+                    {
+                        var chainHeight = view.GetChainHeight();
+                        if (lastSeenHeight < chainHeight)
+                        {
+                            ProcessBlocks(Enumerable.Range(
+                                    (int)lastSeenHeight + 1,
+                                    (int)chainHeight - (int)lastSeenHeight)
+                                .Select(x => view.GetBlock((long)x)));
+                        }
+                    }
+                    catch
                     {
-                        ProcessBlocks(Enumerable.Range(
-                                (int)lastSeenHeight + 1,
-                                (int)chainHeight - (int)lastSeenHeight)
-                            .Select(x => view.GetBlock((long)x)));
+                        await Task.Delay(100);
+                        continue;
                     }
 
                     try