- Fix over payment issue for the KAS family, due to the node accepting the submission of multiple identical blocks

Author: ceedii

src/Miningcore/Blockchain/Kaspa/KaspaPayoutHandler.cs

@@ -154,15 +154,27 @@ public virtual async Task<Block[]> ClassifyBlocksAsync(IMiningPool pool, Block[]
                 .Skip(i * pageSize)
                 .Take(pageSize)
                 .ToArray();
-            
+    
             for(var j = 0; j < page.Length; j++)
             {
                 var block = page[j];
-                
+
+                // There is a case scenario:
+                // https://github.com/blackmennewstyle/miningcore/issues/191
+                // Sadly miners can submit different solutions which will produce the exact same blockHash for the same block
+                // We must handle that case carefully here, otherwise we will overpay our miners.
+                // Only one of these blocks must will be confirmed, the others will all become Orphans
+                uint totalDuplicateBlockBefore = await cf.Run(con => blockRepo.GetPoolDuplicateBlockBeforeCountByPoolHeightAndHashNoTypeAndStatusAsync(con, poolConfig.Id, Convert.ToInt64(block.BlockHeight), block.Hash, new[]
+                {
+                    BlockStatus.Confirmed,
+                    BlockStatus.Orphaned,
+                    BlockStatus.Pending
+                }, block.Created));
+
                 var request = new kaspad.KaspadMessage();
                 request.GetBlockRequest = new kaspad.GetBlockRequestMessage
                 {
-                    Hash = (string) block.Hash,
+                    Hash = block.Hash,
                     IncludeTransactions = true,
                 };
                 await Guard(() => stream.RequestStream.WriteAsync(request),
@@ -181,6 +193,18 @@ await Guard(() => stream.RequestStream.WriteAsync(request),
 
                         messageBus.NotifyBlockUnlocked(poolConfig.Id, block, coin);
                     }
+                    // multiple blocks with the exact same height & hash recorded in the database
+                    else if(totalDuplicateBlockBefore > 0)
+                    {
+                        result.Add(block);
+
+                        block.Status = BlockStatus.Orphaned;
+                        block.Reward = 0;
+
+                        logger.Info(() => $"[{LogCategory}] Block {block.BlockHeight} [{block.Hash}] classified as orphaned because we already have in the database {totalDuplicateBlockBefore} block(s) with the same height and hash");
+
+                        messageBus.NotifyBlockUnlocked(poolConfig.Id, block, coin);
+                    }
                     else
                     {
                         logger.Info(() => $"[{LogCategory}] Block {block.BlockHeight} uses a custom minimum confirmations calculation [{minConfirmations}]");

src/Miningcore/Persistence/Postgres/Repositories/BlockRepository.cs

@@ -244,4 +244,32 @@ public async Task<uint> GetPoolDuplicateBlockAfterCountByPoolHeightNoTypeAndStat
             after
         }));
     }
+
+    public async Task<uint> GetPoolDuplicateBlockBeforeCountByPoolHeightAndHashNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, string hash, BlockStatus[] status, DateTime before)
+    {
+        const string query = @"SELECT COUNT(id) FROM blocks WHERE poolid = @poolId AND blockheight = @height AND hash = @hash AND status = ANY(@status) AND created < @before";
+        
+        return await con.ExecuteScalarAsync<uint>(new CommandDefinition(query, new
+        {
+            poolId,
+            height,
+            hash,
+            status = status.Select(x => x.ToString().ToLower()).ToArray(),
+            before
+        }));
+    }
+
+    public async Task<uint> GetPoolDuplicateBlockAfterCountByPoolHeightAndHashNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, string hash, BlockStatus[] status, DateTime after)
+    {
+        const string query = @"SELECT COUNT(id) FROM blocks WHERE poolid = @poolId AND blockheight = @height AND hash = @hash AND status = ANY(@status) AND created > @after";
+        
+        return await con.ExecuteScalarAsync<uint>(new CommandDefinition(query, new
+        {
+            poolId,
+            height,
+            hash,
+            status = status.Select(x => x.ToString().ToLower()).ToArray(),
+            after
+        }));
+    }
 }

src/Miningcore/Persistence/Repositories/IBlockRepository.cs

@@ -27,4 +27,6 @@ public interface IBlockRepository
     Task<uint> GetPoolDuplicateBlockCountByPoolHeightNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, BlockStatus[] status);
     Task<uint> GetPoolDuplicateBlockBeforeCountByPoolHeightNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, BlockStatus[] status, DateTime before);
     Task<uint> GetPoolDuplicateBlockAfterCountByPoolHeightNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, BlockStatus[] status, DateTime after);
+    Task<uint> GetPoolDuplicateBlockBeforeCountByPoolHeightAndHashNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, string hash, BlockStatus[] status, DateTime before);
+    Task<uint> GetPoolDuplicateBlockAfterCountByPoolHeightAndHashNoTypeAndStatusAsync(IDbConnection con, string poolId, long height, string hash, BlockStatus[] status, DateTime after);
 }