node,consensus: no duplicate proposals allowed #1421
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jchappelow
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| }() | ||
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| from := s.Conn().RemotePeer() | ||
| n.log.Info("Accept proposal?", "height", height, "blockID", prop.Hash, "prevHash", prop.PrevHash, |
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AcceptProposal logs the same, so this can be removed.
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charithabandi
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Feb 27, 2025
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This addresses a strange proposal announcement amplification that can occur given the right timing, which @charithabandi observed once but could not easily reproduce.
In short, to support reannoucement of block proposals as well as preventing malicious spam proposals from stacking up behind the consensus event loop, we made the entire proposal stream handler atomic w.r.t.
AcceptProposal=> download =NotifyBlockProposal. However,NotifyBlockProposalis mostly asynchronous, meaning the next call toAcceptProposalwill return true and allow the same proposal, which includes a full block, to be downloaded again and queued in another consensus msg forNotifyBlockProposal.To resolve this, we take a nearly identical approach to that used with
AcceptCommitand its stream handler. The main difference being that we completely block any subsequent proposal until the prior is processed (either fully rejected or fully accepted and block execution begun).