reconstruct last commit works with legacy chains

internal/consensus/state.go

@@ -695,27 +695,55 @@ func (cs *State) sendInternalMessage(ctx context.Context, mi msgInfo) {
 // Reconstruct LastCommit from SeenCommit, which we saved along with the block,
 // (which happens even before saving the state)
 func (cs *State) reconstructLastCommit(state sm.State) {
-	extCommit := cs.blockStore.LoadExtendedCommit(state.LastBlockHeight)
-	if extCommit == nil {
-		panic(fmt.Sprintf(
-			"failed to reconstruct last commit; commit for height %v not found",
-			state.LastBlockHeight,
-		))
-	}
-
+	requireExtensions := false
 	requireHeight := cs.state.ConsensusParams.Vote.ExtensionRequireHeight
-	if requireHeight != 0 && extCommit.Height >= requireHeight {
-		if err := extCommit.EnsureExtensions(); err != nil {
-			panic(fmt.Sprintf("failed to reconstruct last commit; invalid vote extensions: %v", err))
-		}
+	if requireHeight != 0 && state.LastBlockHeight >= requireHeight {
+		requireExtensions = true
+	}
+	votes, err := cs.votesFromExtendedCommit(state)
+	if err == nil {
+		cs.LastCommit = votes
+		return
+	}
+	if requireExtensions {
+		panic(fmt.Sprintf("failed to reconstruct last commit; %s", err))
+	}
+	votes, err = cs.votesFromSeenCommit(state)
+	if err != nil {
+		panic(fmt.Sprintf("failed to reconstruct last commit; %s", err))
+	}
+	cs.LastCommit = votes
+}
+
+func (cs *State) votesFromExtendedCommit(state sm.State) (*types.VoteSet, error) {
+	ec := cs.blockStore.LoadExtendedCommit(state.LastBlockHeight)
+	if ec == nil {
+		return nil, fmt.Errorf("commit for height %v not found", state.LastBlockHeight)
+	}
+	if err := ec.EnsureExtensions(); err != nil {
+		return nil, fmt.Errorf("invalid vote extensions: %v", err)
+	}
+	vs := ec.ToVoteSet(state.ChainID, state.LastValidators)
+	if !vs.HasTwoThirdsMajority() {
+		return nil, errors.New("seen commit does not have +2/3 majority")
+	}
+	return vs, nil
+}
+
+func (cs *State) votesFromSeenCommit(state sm.State) (*types.VoteSet, error) {
+	commit := cs.blockStore.LoadSeenCommit()
+	if commit == nil || commit.Height != state.LastBlockHeight {
+		commit = cs.blockStore.LoadBlockCommit(state.LastBlockHeight)
+	}
+	if commit == nil {
+		return nil, fmt.Errorf("commit for height %v not found", state.LastBlockHeight)
 	}
 
-	lastPrecommits := extCommit.ToVoteSet(state.ChainID, state.LastValidators)
-	if !lastPrecommits.HasTwoThirdsMajority() {
-		panic("failed to reconstruct last commit; does not have +2/3 maj")
+	vs := commit.ToVoteSet(state.ChainID, state.LastValidators)
+	if !vs.HasTwoThirdsMajority() {
+		return nil, errors.New("commit does not have +2/3 majority")
 	}
-
-	cs.LastCommit = lastPrecommits
+	return vs, nil
 }
 
 // Updates State and increments height to match that of state.

types/block.go

@@ -1038,6 +1038,27 @@ func (ec *ExtendedCommit) ToVoteSet(chainID string, vals *ValidatorSet) *VoteSet
 	return voteSet
 }
 
+// ToVoteSet constructs a VoteSet from the Commit and validator set.
+// Panics if signatures from the commit can't be added to the voteset.
+// Inverse of VoteSet.MakeCommit().
+func (c *Commit) ToVoteSet(chainID string, vals *ValidatorSet) *VoteSet {
+	voteSet := NewVoteSet(chainID, c.Height, c.Round, tmproto.PrecommitType, vals)
+	for idx, cs := range c.Signatures {
+		if cs.BlockIDFlag == BlockIDFlagAbsent {
+			continue // OK, some precommits can be missing.
+		}
+		vote := c.GetVote(int32(idx))
+		if err := vote.ValidateBasic(); err != nil {
+			panic(fmt.Errorf("failed to validate vote reconstructed from commit: %w", err))
+		}
+		added, err := voteSet.AddVote(vote)
+		if !added || err != nil {
+			panic(fmt.Errorf("failed to reconstruct vote set from commit: %w", err))
+		}
+	}
+	return voteSet
+}
+
 // TODO Comment
 // this should probably also verify the signature
 // probably want to change to just verify when present.