Throw exception with network based on different genesis

CHANGES.md

@@ -92,6 +92,8 @@ To be released.
     continuous.  [[#732]]
  -  `Swarm<T>` became to can process more requests at once by creating TURN
     relaying proxy concurrently.  [[#744]]
+ -  `Swarm<T>` became to throw `InvalidGenesisBlockException` when receiving
+    block from the nodes that have a different genesis block.  [[#746]]
 
 ### Bug fixes
 
@@ -160,6 +162,7 @@ To be released.
 [#736]: https://github.com/planetarium/libplanet/pull/736
 [#739]: https://github.com/planetarium/libplanet/pull/739
 [#744]: https://github.com/planetarium/libplanet/pull/744
+[#746]: https://github.com/planetarium/libplanet/pull/746
 
 
 Version 0.7.0

Libplanet.Tests/Net/SwarmTest.cs

@@ -2590,6 +2590,39 @@ public async Task DoNotReceiveBlockFromNodeHavingDifferenceGenesisBlock()
             }
         }
 
+        [Fact(Timeout = Timeout)]
+        public async Task ThrowInvalidGenesisException()
+        {
+            var policy = new BlockPolicy<DumbAction>();
+            BlockChain<DumbAction> MakeBlockChain() => TestUtils.MakeBlockChain(
+                policy,
+                new DefaultStore(path: null),
+                null,
+                new PrivateKey());
+
+            var chainA = MakeBlockChain();
+            var chainB = MakeBlockChain();
+            var swarmA = CreateSwarm(chainA);
+            var swarmB = CreateSwarm(chainB);
+
+            await chainB.MineBlock(_fx1.Address1);
+
+            await StartAsync(swarmA);
+            await StartAsync(swarmB);
+
+            await swarmA.AddPeersAsync(new[] { swarmB.AsPeer }, null);
+            Assert.NotEqual(chainA.Genesis, chainB.Genesis);
+            Task t = swarmA.PreloadAsync();
+            await Assert.ThrowsAsync<AggregateException>(async () => await t);
+            var exception = t.Exception.InnerException?.InnerException;
+            Assert.IsType<InvalidGenesisBlockException>(exception);
+
+            await StopAsync(swarmA);
+            await StopAsync(swarmB);
+            swarmA.Dispose();
+            swarmB.Dispose();
+        }
+
         [Fact(Timeout = Timeout)]
         public async Task FindSpecificPeerAsync()
         {

Libplanet/Blocks/InvalidGenesisBlockException.cs

@@ -8,7 +8,9 @@ namespace Libplanet.Blocks
     /// <summary>
     /// The exception that is thrown when the genesis block the <see cref="IStore"/> contains
     /// mismatches to the genesis block the <see cref="BlockChain{T}"/> constructor (i.e., network)
-    /// expects.
+    /// expects or the first block of <see cref="BlockLocator"/> which the <see cref="IStore"/>
+    /// doesn't contain, because the block which <see cref="IStore"/> doesn't means
+    /// the genesis block in other network.
     /// </summary>
     public class InvalidGenesisBlockException : InvalidBlockException
     {

Libplanet/Net/Swarm.cs

@@ -1910,11 +1910,15 @@ await GetBlockHashesAsync(peer, locator, stop, cancellationToken)
                     // same genesis block...
                     else if (!BlockChain.ContainsBlock(branchPoint))
                     {
-                        _logger.Debug(
+                        var msg =
                             $"Since the genesis block is fixed to {BlockChain.Genesis} " +
                             "protocol-wise, the blockchain which does not share " +
-                            "any mutual block is not acceptable.");
-                        break;
+                            "any mutual block is not acceptable.";
+                        _logger.Debug(msg);
+                        throw new InvalidGenesisBlockException(
+                            branchPoint,
+                            workspace.Genesis.Hash,
+                            msg);
                     }
                     else
                     {

Menees.Analyzers.Settings.xml

@@ -2,5 +2,5 @@
 <Menees.Analyzers.Settings>
   <MaxLineColumns>100</MaxLineColumns>
   <MaxMethodLines>200</MaxMethodLines>
-  <MaxFileLines>2800</MaxFileLines>
+  <MaxFileLines>2900</MaxFileLines>
 </Menees.Analyzers.Settings>