From a20a485dbe6c41b435211266eea0e794c1e499c4 Mon Sep 17 00:00:00 2001
From: Thane Thomson <connect@thanethomson.com>
Date: Sat, 7 May 2022 09:40:38 -0400
Subject: [PATCH] Propagate validator info to PrepareProposal

In order to propagate validator voting power through to PrepareProposal,
we need to load the validator set info from the height corresponding to
the extended commit that we're passing through to PrepareProposal as the
"LocalLastCommit".

Signed-off-by: Thane Thomson <connect@thanethomson.com>
---
 internal/state/execution.go | 62 +++++++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 19 deletions(-)

diff --git a/internal/state/execution.go b/internal/state/execution.go
index b1617a4f9..3c2fb2b89 100644
--- a/internal/state/execution.go
+++ b/internal/state/execution.go
@@ -86,7 +86,7 @@ func (blockExec *BlockExecutor) CreateProposalBlock(
 	ctx context.Context,
 	height int64,
 	state State,
-	extCommit *types.ExtendedCommit,
+	lastExtCommit *types.ExtendedCommit,
 	proposerAddr []byte,
 ) (*types.Block, error) {
 
@@ -99,15 +99,16 @@ func (blockExec *BlockExecutor) CreateProposalBlock(
 	maxDataBytes := types.MaxDataBytes(maxBytes, evSize, state.Validators.Size())
 
 	txs := blockExec.mempool.ReapMaxBytesMaxGas(maxDataBytes, maxGas)
-	commit := extCommit.StripExtensions()
+	commit := lastExtCommit.StripExtensions()
 	block := state.MakeBlock(height, txs, commit, evidence, proposerAddr)
 
+	fmt.Printf("height = %d, lastExtCommit.Height = %d\n", height, lastExtCommit.Height)
 	rpp, err := blockExec.appClient.PrepareProposal(
 		ctx,
 		&abci.RequestPrepareProposal{
 			MaxTxBytes:          maxDataBytes,
 			Txs:                 block.Txs.ToSliceOfBytes(),
-			LocalLastCommit:     extendedCommitInfo(*extCommit),
+			LocalLastCommit:     buildLastExtendedCommitInfo(lastExtCommit, blockExec.store, state.InitialHeight),
 			ByzantineValidators: block.Evidence.ToABCI(),
 			Height:              block.Height,
 			Time:                block.Time,
@@ -375,14 +376,14 @@ func (blockExec *BlockExecutor) Commit(
 
 func buildLastCommitInfo(block *types.Block, store Store, initialHeight int64) abci.CommitInfo {
 	if block.Height == initialHeight {
-		// there is no last commmit for the initial height.
+		// there is no last commit for the initial height.
 		// return an empty value.
 		return abci.CommitInfo{}
 	}
 
 	lastValSet, err := store.LoadValidators(block.Height - 1)
 	if err != nil {
-		panic(err)
+		panic(fmt.Errorf("failed to load validator set at height %d: %w", block.Height-1, err))
 	}
 
 	var (
@@ -414,28 +415,51 @@ func buildLastCommitInfo(block *types.Block, store Store, initialHeight int64) a
 	}
 }
 
-// extendedCommitInfo expects an ExtendedCommitInfo, which includes the
-// original precommit votes along with their vote extensions.
-// Then, it populates the corresponding ABCI protobuf structures.
-func extendedCommitInfo(extCommit types.ExtendedCommit) abci.ExtendedCommitInfo {
-	vs := make([]abci.ExtendedVoteInfo, len(extCommit.ExtendedSignatures))
-	for i, ecs := range extCommit.ExtendedSignatures {
+// buildLastExtendedCommitInfo expects an ExtendedCommitInfo, which includes
+// the original precommit votes along with their vote extensions from the last
+// commit. It populates the corresponding ABCI protobuf structures using the
+// validator set obtained from the store at the height of the last extended
+// commit.
+func buildLastExtendedCommitInfo(ec *types.ExtendedCommit, store Store, initialHeight int64) abci.ExtendedCommitInfo {
+	// The current height is ec.Height+1
+	if ec.Height+1 == initialHeight {
+		// There is no extended commit for the initial height.
+		return abci.ExtendedCommitInfo{}
+	}
+
+	valSet, err := store.LoadValidators(ec.Height)
+	if err != nil {
+		panic(fmt.Errorf("failed to load validator set at height %d: %w", ec.Height, err))
+	}
+
+	vs := make([]abci.ExtendedVoteInfo, ec.Size())
+	for i, ecs := range ec.ExtendedSignatures {
 		var ext []byte
-		if ecs.ForBlock() {
+		if ecs.BlockIDFlag == types.BlockIDFlagCommit {
+			// We only care about vote extensions if a validator has voted to
+			// commit.
 			ext = ecs.VoteExtension
 		}
+		var vpb abci.Validator
+		// The ValidatorAddress field is empty when their vote is absent.
+		if ecs.BlockIDFlag != types.BlockIDFlagAbsent {
+			_, val := valSet.GetByAddress(ecs.ValidatorAddress)
+			if val == nil {
+				panic(fmt.Sprintf(
+					"cannot find validator with address '%s' from extended commit in validator set from height %d",
+					ecs.ValidatorAddress, ec.Height,
+				))
+			}
+			vpb = types.TM2PB.Validator(val)
+		}
 		vs[i] = abci.ExtendedVoteInfo{
-			Validator: abci.Validator{
-				Address: ecs.ValidatorAddress,
-				//TODO: Important: why do we need power here?
-				Power: 0,
-			},
-			SignedLastBlock: ecs.ForBlock(),
+			Validator:       vpb,
+			SignedLastBlock: ecs.BlockIDFlag != types.BlockIDFlagAbsent,
 			VoteExtension:   ext,
 		}
 	}
 	return abci.ExtendedCommitInfo{
-		Round: extCommit.Round,
+		Round: ec.Round,
 		Votes: vs,
 	}
 }