fix: Allow VerifyVoteExtensions without ExtendVote (backport #17251) (#17254)

Co-authored-by: Facundo Medica <14063057+facundomedica@users.noreply.github.com>

CHANGELOG.md

@@ -51,6 +51,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (baseapp) [#17251](https://github.com/cosmos/cosmos-sdk/pull/17251) VerifyVoteExtensions and ExtendVote initialize their own contexts/states, allowing VerifyVoteExtensions being called without ExtendVote.
 * (x/auth) [#17209](https://github.com/cosmos/cosmos-sdk/pull/17209) Internal error on AccountInfo when account's public key is not set.
 * (baseapp) [#17159](https://github.com/cosmos/cosmos-sdk/pull/17159) Validators can propose blocks that exceed the gas limit.
 * (x/group) [#17146](https://github.com/cosmos/cosmos-sdk/pull/17146) Rename x/group legacy ORM package's error codespace from "orm" to "legacy_orm", preventing collisions with ORM's error codespace "orm".

baseapp/abci.go

@@ -548,7 +548,8 @@ func (app *BaseApp) ExtendVote(_ context.Context, req *abci.RequestExtendVote) (
 	// Always reset state given that ExtendVote and VerifyVoteExtension can timeout
 	// and be called again in a subsequent round.
 	emptyHeader := cmtproto.Header{ChainID: app.chainID, Height: req.Height}
-	app.setState(execModeVoteExtension, emptyHeader)
+	ms := app.cms.CacheMultiStore()
+	ctx := sdk.NewContext(ms, emptyHeader, false, app.logger).WithStreamingManager(app.streamingManager)
 
 	if app.extendVote == nil {
 		return nil, errors.New("application ExtendVote handler not set")
@@ -556,14 +557,14 @@ func (app *BaseApp) ExtendVote(_ context.Context, req *abci.RequestExtendVote) (
 
 	// If vote extensions are not enabled, as a safety precaution, we return an
 	// error.
-	cp := app.GetConsensusParams(app.voteExtensionState.ctx)
+	cp := app.GetConsensusParams(ctx)
 
 	extsEnabled := cp.Abci != nil && req.Height >= cp.Abci.VoteExtensionsEnableHeight && cp.Abci.VoteExtensionsEnableHeight != 0
 	if !extsEnabled {
 		return nil, fmt.Errorf("vote extensions are not enabled; unexpected call to ExtendVote at height %d", req.Height)
 	}
 
-	app.voteExtensionState.ctx = app.voteExtensionState.ctx.
+	ctx = ctx.
 		WithConsensusParams(cp).
 		WithBlockGasMeter(storetypes.NewInfiniteGasMeter()).
 		WithBlockHeight(req.Height).
@@ -588,7 +589,7 @@ func (app *BaseApp) ExtendVote(_ context.Context, req *abci.RequestExtendVote) (
 		}
 	}()
 
-	resp, err = app.extendVote(app.voteExtensionState.ctx, req)
+	resp, err = app.extendVote(ctx, req)
 	if err != nil {
 		app.logger.Error("failed to extend vote", "height", req.Height, "error", err)
 		return &abci.ResponseExtendVote{VoteExtension: []byte{}}, nil
@@ -608,9 +609,13 @@ func (app *BaseApp) VerifyVoteExtension(req *abci.RequestVerifyVoteExtension) (r
 		return nil, errors.New("application VerifyVoteExtension handler not set")
 	}
 
+	emptyHeader := cmtproto.Header{ChainID: app.chainID, Height: req.Height}
+	ms := app.cms.CacheMultiStore()
+	ctx := sdk.NewContext(ms, emptyHeader, false, app.logger).WithStreamingManager(app.streamingManager)
+
 	// If vote extensions are not enabled, as a safety precaution, we return an
 	// error.
-	cp := app.GetConsensusParams(app.voteExtensionState.ctx)
+	cp := app.GetConsensusParams(ctx)
 
 	extsEnabled := cp.Abci != nil && req.Height >= cp.Abci.VoteExtensionsEnableHeight && cp.Abci.VoteExtensionsEnableHeight != 0
 	if !extsEnabled {
@@ -631,7 +636,7 @@ func (app *BaseApp) VerifyVoteExtension(req *abci.RequestVerifyVoteExtension) (r
 		}
 	}()
 
-	resp, err = app.verifyVoteExt(app.voteExtensionState.ctx, req)
+	resp, err = app.verifyVoteExt(ctx, req)
 	if err != nil {
 		app.logger.Error("failed to verify vote extension", "height", req.Height, "error", err)
 		return &abci.ResponseVerifyVoteExtension{Status: abci.ResponseVerifyVoteExtension_REJECT}, nil

baseapp/abci_test.go

@@ -364,6 +364,63 @@ func TestABCI_ExtendVote(t *testing.T) {
 	require.Equal(t, abci.ResponseVerifyVoteExtension_REJECT, vres.Status)
 }
 
+// TestABCI_OnlyVerifyVoteExtension makes sure we can call VerifyVoteExtension
+// without having called ExtendVote before.
+func TestABCI_OnlyVerifyVoteExtension(t *testing.T) {
+	name := t.Name()
+	db := dbm.NewMemDB()
+	app := baseapp.NewBaseApp(name, log.NewTestLogger(t), db, nil)
+
+	app.SetVerifyVoteExtensionHandler(func(ctx sdk.Context, req *abci.RequestVerifyVoteExtension) (*abci.ResponseVerifyVoteExtension, error) {
+		// do some kind of verification here
+		expectedVoteExt := "foo" + hex.EncodeToString(req.Hash) + strconv.FormatInt(req.Height, 10)
+		if !bytes.Equal(req.VoteExtension, []byte(expectedVoteExt)) {
+			return &abci.ResponseVerifyVoteExtension{Status: abci.ResponseVerifyVoteExtension_REJECT}, nil
+		}
+
+		return &abci.ResponseVerifyVoteExtension{Status: abci.ResponseVerifyVoteExtension_ACCEPT}, nil
+	})
+
+	app.SetParamStore(&paramStore{db: dbm.NewMemDB()})
+	_, err := app.InitChain(
+		&abci.RequestInitChain{
+			InitialHeight: 1,
+			ConsensusParams: &cmtproto.ConsensusParams{
+				Abci: &cmtproto.ABCIParams{
+					VoteExtensionsEnableHeight: 200,
+				},
+			},
+		},
+	)
+	require.NoError(t, err)
+
+	// Verify Vote Extensions
+	_, err = app.VerifyVoteExtension(&abci.RequestVerifyVoteExtension{Height: 123, VoteExtension: []byte("1234567")})
+	require.ErrorContains(t, err, "vote extensions are not enabled")
+
+	// First vote on the first enabled height
+	vres, err := app.VerifyVoteExtension(&abci.RequestVerifyVoteExtension{Height: 200, Hash: []byte("thehash"), VoteExtension: []byte("foo74686568617368200")})
+	require.NoError(t, err)
+	require.Equal(t, abci.ResponseVerifyVoteExtension_ACCEPT, vres.Status)
+
+	vres, err = app.VerifyVoteExtension(&abci.RequestVerifyVoteExtension{Height: 1000, Hash: []byte("thehash"), VoteExtension: []byte("foo746865686173681000")})
+	require.NoError(t, err)
+	require.Equal(t, abci.ResponseVerifyVoteExtension_ACCEPT, vres.Status)
+
+	// Reject because it's just some random bytes
+	vres, err = app.VerifyVoteExtension(&abci.RequestVerifyVoteExtension{Height: 201, Hash: []byte("thehash"), VoteExtension: []byte("12345678")})
+	require.NoError(t, err)
+	require.Equal(t, abci.ResponseVerifyVoteExtension_REJECT, vres.Status)
+
+	// Reject because the verification failed (no error)
+	app.SetVerifyVoteExtensionHandler(func(ctx sdk.Context, req *abci.RequestVerifyVoteExtension) (*abci.ResponseVerifyVoteExtension, error) {
+		return nil, errors.New("some error")
+	})
+	vres, err = app.VerifyVoteExtension(&abci.RequestVerifyVoteExtension{Height: 201, Hash: []byte("thehash"), VoteExtension: []byte("12345678")})
+	require.NoError(t, err)
+	require.Equal(t, abci.ResponseVerifyVoteExtension_REJECT, vres.Status)
+}
+
 func TestABCI_GRPCQuery(t *testing.T) {
 	grpcQueryOpt := func(bapp *baseapp.BaseApp) {
 		testdata.RegisterQueryServer(

baseapp/baseapp.go

@@ -104,11 +104,6 @@ type BaseApp struct {
 	// previous block's state. This state is never committed. In case of multiple
 	// consensus rounds, the state is always reset to the previous block's state.
 	//
-	// - voteExtensionState: Used for ExtendVote and VerifyVoteExtension, which is
-	// set based on the previous block's state. This state is never committed. In
-	// case of multiple rounds, the state is always reset to the previous block's
-	// state.
-	//
 	// - processProposalState: Used for ProcessProposal, which is set based on the
 	// the previous block's state. This state is never committed. In case of
 	// multiple rounds, the state is always reset to the previous block's state.
@@ -118,7 +113,6 @@ type BaseApp struct {
 	checkState           *state
 	prepareProposalState *state
 	processProposalState *state
-	voteExtensionState   *state
 	finalizeBlockState   *state
 
 	// An inter-block write-through cache provided to the context during the ABCI
@@ -475,9 +469,6 @@ func (app *BaseApp) setState(mode execMode, header cmtproto.Header) {
 	case execModeProcessProposal:
 		app.processProposalState = baseState
 
-	case execModeVoteExtension:
-		app.voteExtensionState = baseState
-
 	case execModeFinalize:
 		app.finalizeBlockState = baseState
 

docs/architecture/adr-064-abci-2.0.md

@@ -105,10 +105,11 @@ type ExtendVoteHandler func(sdk.Context, abci.RequestExtendVote) abci.ResponseEx
 type VerifyVoteExtensionHandler func(sdk.Context, abci.RequestVerifyVoteExtension) abci.ResponseVerifyVoteExtension
 ```
 
-A new execution state, `voteExtensionState`, will be introduced and provided as
-the `Context` that is supplied to both handlers. It will contain relevant metadata
-such as the block height and block hash. Note, `voteExtensionState` is never
-committed and will exist as ephemeral state only in the context of a single block.
+An ephemeral context and state will be supplied to both handlers. The
+context will contain relevant metadata such as the block height and block hash.
+The state will be a cached version of the committed state of the application and
+will be discarded after the execution of the handler, this means that both handlers
+get a fresh state view and no changes made to it will be written.
 
 If an application decides to implement `ExtendVoteHandler`, it must return a
 non-nil `ResponseExtendVote.VoteExtension`.

docs/docs/core/00-baseapp.md

@@ -90,7 +90,6 @@ Then, parameters used to define [volatile states](#state-updates) (i.e. cached s
   [`Commit`](#commit) and gets re-initialized on `FinalizeBlock`.
 * `processProposalState`: This state is updated during [`ProcessProposal`](#process-proposal).
 * `prepareProposalState`: This state is updated during [`PrepareProposal`](#prepare-proposal).
-* `voteExtensionState`: This state is updated during [`ExtendVote`](#extendvote) & [`VerifyVoteExtension`](#verifyvoteextension).
 
 Finally, a few more important parameters:
 
@@ -130,7 +129,7 @@ Naturally, developers can add additional `options` based on their application's
 ## State Updates
 
 The `BaseApp` maintains four primary volatile states and a root or main state. The main state
-is the canonical state of the application and the volatile states, `checkState`, `prepareProposalState`, `processProposalState`, `voteExtensionState` and `finalizeBlockState`
+is the canonical state of the application and the volatile states, `checkState`, `prepareProposalState`, `processProposalState` and `finalizeBlockState`
 are used to handle state transitions in-between the main state made during [`Commit`](#commit).
 
 Internally, there is only a single `CommitMultiStore` which we refer to as the main or root state.