Fix deficiency in ABCI interface: SignedLastBlock
#540
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This was referenced Mar 16, 2023
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jmalicevic
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Mar 16, 2023
| if len(vote.VoteExtension) != 0 { | ||
| return 0, fmt.Errorf("non-empty vote extension at height %d, which has extensions disabled", currentHeight) | ||
| return 0, fmt.Errorf("non-empty vote extension at height %d, for a vote with blockID flag %d", |
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Essentially, if this validator had voted correctly, and there is an extension, the flag had to have been Commit?
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Exactly:
- BlockIDFlagAbsent means it didn't precommit so, how come we got a vote extension?
- BlockIDFlagNil means it precommitted for
nil, butnilprecommits don't have vote extensions
In both cases the info we get is contradictory, so we should reject it.
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Oh, did you mean that we could simplify the condition in line 583 like this?
if vote.BlockIdFlag != cmtproto.BlockIDFlagCommit {
jmalicevic
reviewed
Mar 16, 2023
jmalicevic
approved these changes
Mar 16, 2023
Co-authored-by: Jasmina Malicevic <jasmina.dustinac@gmail.com>
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Contributes to #485
Current ABCI 2.0 implementation has
VoteInfoandExtendedVoteInfoto send vote signature information to the application at several points in the interaction:PrepareProposalProcessProposalFinalizeBlockThe problem with
VoteInfoandExtendedVoteInfois that they contain abool, calledSignedLastBlock, which collapses several cases: (a) did the sending validator precommit fornil? (b) did it precommit for the decided block? (c) did they not precommit (or no precommit received, absent)?SignedLastBlockis collapsing cases (a) and (b) into valuetrueof the boolean, hiding potentially useful information to the application.With vote extensions, this has become a bigger problem, as we are unable to "ensure" from a testing application that the vote extensions are present or absent at the right time. If we (CometBFT team) are unable to test this properly, then real apps may have a very hard time troubleshooting potential problems on the field, due to some info being trapped south of ABCI.
After a discussion with @ebuchman, we have decided to fix this problem, which was already fixed long ago in the block-related protos (see discussion). The conclusion was that this is the right moment, as we are heavily changing ABCI in this release, and it's not certain when we will need to make substantial changes to it in the mid-term.
This PR contains the changes needed in the protobufs and in the code.
PR checklist
.changelog(we use unclog to manage our changelog)docs/orspec/) and code comments