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Fix randomly failing receipt deserialization #5120

Merged
merged 3 commits into from
Jan 10, 2023
Merged

Fix randomly failing receipt deserialization #5120

merged 3 commits into from
Jan 10, 2023

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asdacap
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@asdacap asdacap commented Jan 10, 2023

Fix #5116

  • Occationally there are unexplainable run with lots of dropping peers.
  • Closer inspection shows that the node is disconnecting peers due to error in forward sync, specifically empty receipt received.
  • Anyway, it turns out that there is a bug in the receipt deserialization logic which can get triggered if the first element of the byte buffer allocated in ZeroNettyP2PHandler is equal to Rlp.OfEmptySequence[0].

Changes

  • Fix deserialization bug.
  • Added extra check in ProtocolHandlerBase that helped me debug this issue.

Types of changes

  • Bugfix (a non-breaking change that fixes an issue)

Testing

Requires testing

  • Yes
  • No

If yes, did you write tests?

  • Yes
  • No

Notes on testing

  • Can by triggered manually by something like this in ZeroNettyP2PHandler.
                IByteBuffer output = PooledByteBufferAllocator.Default.Buffer(uncompressedLength + 1);
                output.WriteByte(Rlp.OfEmptySequence[0]);
                output.ReadByte();

@asdacap asdacap requested a review from kamilchodola January 10, 2023 11:30
LukaszRozmej
LukaszRozmej approved these changes Jan 10, 2023
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src/Nethermind/Nethermind.Network/P2P/ProtocolHandlers/ProtocolHandlerBase.cs
T result = _serializer.Deserialize<T>(data);
if (data.IsReadable())
{
throw new IncompleteDeserializationException(
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What does that exception achieve?

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Make it easier to detect deserialization issue.

LukaszRozmej
LukaszRozmej reviewed Jan 10, 2023
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...Nethermind/Nethermind.Network/P2P/Subprotocols/Eth/V63/Messages/ReceiptsMessageSerializer.cs Outdated
if (byteBuffer.Array.Length == 0 || byteBuffer.Array.First() == Rlp.OfEmptySequence[0]) return new ReceiptsMessage(null);
if (byteBuffer.ReadableBytes == 0)
{
return new ReceiptsMessage(null);
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Wouldn't it be better to have some ReceiptsMessage.Empty ?

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Sure enough.

@asdacap asdacap merged commit 1edfd97 into master Jan 10, 2023
@asdacap asdacap deleted the fix/random-receipt-deserialization-failure branch January 10, 2023 14:01
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@LukaszRozmej LukaszRozmej LukaszRozmej approved these changes

@kamilchodola kamilchodola Awaiting requested review from kamilchodola

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@asdacap @LukaszRozmej