refactor: Revert middlewares to antehandler (part 2/2: posthandler) (#…

…11985)

## Description

We decided to remove middlewares, and revert to antehandlers (exactly like in v045) for this release. A better middleware solution will be implemented after v046.

ref: #11955

This PR is part 2 of 2:

- part 1: Revert baseapp and middlewares to v0.45.4
- part 2: Add posthandler, tips, priority

Depends on:
- [x] #11979 

---

Suggestion for reviewers:

- Apart from correctness, I would also like someone to review **exhaustiveness**. I.e. all changes we made in v046 into the [middleware folder](https://github.com/cosmos/cosmos-sdk/tree/v0.46.0-beta2/x/auth/middleware) are reflected in this PR, and that I didn't forget anything. I found the following ones:
  - add a TxFeeChecker in DeductFee
  - add a ExtensionChecker in ExtCheckerDecorator
  - add a TipDecorator



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -39,6 +39,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Features
 
+* (types) [#11985](https://github.com/cosmos/cosmos-sdk/pull/11985) Add a `Priority` field on `sdk.Context`, which represents the CheckTx priority field. It is only used during CheckTx.
 * (gRPC) [#11889](https://github.com/cosmos/cosmos-sdk/pull/11889) Support custom read and write gRPC options in `app.toml`. See `max-recv-msg-size` and `max-send-msg-size` respectively.
 * (cli) [\#11738](https://github.com/cosmos/cosmos-sdk/pull/11738) Add `tx auth multi-sign` as alias of `tx auth multisign` for consistency with `multi-send`.
 * (cli) [\#11738](https://github.com/cosmos/cosmos-sdk/pull/11738) Add `tx bank multi-send` command for bulk send of coins to multiple accounts.
@@ -90,6 +91,8 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking Changes
 
+* (x/auth/ante) [#11985](https://github.com/cosmos/cosmos-sdk/pull/11985) The `MempoolFeeDecorator` has been removed. Instead, the `DeductFeeDecorator` takes a new argument of type `TxFeeChecker`, to define custom fee models. If `nil` is passed to this `TxFeeChecker` argument, then it will default to `checkTxFeeWithValidatorMinGasPrices`, which is the exact same behavior as the old `MempoolFeeDecorator` (i.e. checking fees against validator's own min gas price).
+* (x/auth/ante) [#11985](https://github.com/cosmos/cosmos-sdk/pull/11985) The `ExtensionOptionsDecorator` takes an argument of type `ExtensionOptionChecker`. For backwards-compatibility, you can pass `nil`, which defaults to the old behavior of rejecting all tx extensions.
 * (crypto/keyring) [#11932](https://github.com/cosmos/cosmos-sdk/pull/11932) Remove `Unsafe*` interfaces from keyring package. Please use interface casting if you wish to access those unsafe functions.
 * (types) [#11881](https://github.com/cosmos/cosmos-sdk/issues/11881) Rename `AccAddressFromHex` to `AccAddressFromHexUnsafe`.
 * (types) [#11788](https://github.com/cosmos/cosmos-sdk/pull/11788) The `Int` and `Uint` types have been moved to their own dedicated module, `math`. Aliases are kept in the SDK's root `types` package, however, it is encouraged to utilize the new `math` module. As a result, the `Int#ToDec` API has been removed.
@@ -277,6 +280,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### State Machine Breaking
 
+* (baseapp) [\#11985](https://github.com/cosmos/cosmos-sdk/pull/11985) Add a `postHandler` to baseapp. This `postHandler` is like antehandler, but is run _after_ the `runMsgs` execution. It is in the same store branch that `runMsgs`, meaning that both `runMsgs` and `postHandler`
 * (x/gov) [#11998](https://github.com/cosmos/cosmos-sdk/pull/11998) Tweak the `x/gov` `ModuleAccountInvariant` invariant to ensure deposits are `<=` total module account balance instead of strictly equal.
 * (x/upgrade) [\#11800](https://github.com/cosmos/cosmos-sdk/pull/11800) Fix `GetLastCompleteUpgrade` to properly return the latest upgrade.
 * [\#10564](https://github.com/cosmos/cosmos-sdk/pull/10564) Fix bug when updating allowance inside AllowedMsgAllowance

baseapp/abci.go

@@ -251,7 +251,7 @@ func (app *BaseApp) CheckTx(req abci.RequestCheckTx) abci.ResponseCheckTx {
 		panic(fmt.Sprintf("unknown RequestCheckTx type: %s", req.Type))
 	}
 
-	gInfo, result, anteEvents, err := app.runTx(mode, req.Tx)
+	gInfo, result, anteEvents, priority, err := app.runTx(mode, req.Tx)
 	if err != nil {
 		return sdkerrors.ResponseCheckTxWithEvents(err, gInfo.GasWanted, gInfo.GasUsed, anteEvents, app.trace)
 	}
@@ -262,6 +262,7 @@ func (app *BaseApp) CheckTx(req abci.RequestCheckTx) abci.ResponseCheckTx {
 		Log:       result.Log,
 		Data:      result.Data,
 		Events:    sdk.MarkEventsToIndex(result.Events, app.indexEvents),
+		Priority:  priority,
 	}
 }
 
@@ -281,7 +282,7 @@ func (app *BaseApp) DeliverTx(req abci.RequestDeliverTx) abci.ResponseDeliverTx
 		telemetry.SetGauge(float32(gInfo.GasWanted), "tx", "gas", "wanted")
 	}()
 
-	gInfo, result, anteEvents, err := app.runTx(runTxModeDeliver, req.Tx)
+	gInfo, result, anteEvents, _, err := app.runTx(runTxModeDeliver, req.Tx)
 	if err != nil {
 		resultStr = "failed"
 		return sdkerrors.ResponseDeliverTxWithEvents(err, gInfo.GasWanted, gInfo.GasUsed, anteEvents, app.trace)

baseapp/baseapp.go

@@ -58,6 +58,7 @@ type BaseApp struct { // nolint: maligned
 	txDecoder         sdk.TxDecoder // unmarshal []byte into sdk.Tx
 
 	anteHandler    sdk.AnteHandler  // ante handler for fee and auth
+	postHandler    sdk.AnteHandler  // post handler, optional, e.g. for tips
 	initChainer    sdk.InitChainer  // initialize state with validators and state blob
 	beginBlocker   sdk.BeginBlocker // logic to run before any txs
 	endBlocker     sdk.EndBlocker   // logic to run after all txs, and to determine valset changes
@@ -584,7 +585,7 @@ func (app *BaseApp) cacheTxContext(ctx sdk.Context, txBytes []byte) (sdk.Context
 // Note, gas execution info is always returned. A reference to a Result is
 // returned if the tx does not run out of gas and if all the messages are valid
 // and execute successfully. An error is returned otherwise.
-func (app *BaseApp) runTx(mode runTxMode, txBytes []byte) (gInfo sdk.GasInfo, result *sdk.Result, anteEvents []abci.Event, err error) {
+func (app *BaseApp) runTx(mode runTxMode, txBytes []byte) (gInfo sdk.GasInfo, result *sdk.Result, anteEvents []abci.Event, priority int64, err error) {
 	// NOTE: GasWanted should be returned by the AnteHandler. GasUsed is
 	// determined by the GasMeter. We need access to the context to get the gas
 	// meter so we initialize upfront.
@@ -595,7 +596,7 @@ func (app *BaseApp) runTx(mode runTxMode, txBytes []byte) (gInfo sdk.GasInfo, re
 
 	// only run the tx if there is block gas remaining
 	if mode == runTxModeDeliver && ctx.BlockGasMeter().IsOutOfGas() {
-		return gInfo, nil, nil, sdkerrors.Wrap(sdkerrors.ErrOutOfGas, "no block gas left to run tx")
+		return gInfo, nil, nil, 0, sdkerrors.Wrap(sdkerrors.ErrOutOfGas, "no block gas left to run tx")
 	}
 
 	defer func() {
@@ -630,12 +631,12 @@ func (app *BaseApp) runTx(mode runTxMode, txBytes []byte) (gInfo sdk.GasInfo, re
 
 	tx, err := app.txDecoder(txBytes)
 	if err != nil {
-		return sdk.GasInfo{}, nil, nil, err
+		return sdk.GasInfo{}, nil, nil, 0, err
 	}
 
 	msgs := tx.GetMsgs()
 	if err := validateBasicTxMsgs(msgs); err != nil {
-		return sdk.GasInfo{}, nil, nil, err
+		return sdk.GasInfo{}, nil, nil, 0, err
 	}
 
 	if app.anteHandler != nil {
@@ -671,9 +672,10 @@ func (app *BaseApp) runTx(mode runTxMode, txBytes []byte) (gInfo sdk.GasInfo, re
 		gasWanted = ctx.GasMeter().Limit()
 
 		if err != nil {
-			return gInfo, nil, nil, err
+			return gInfo, nil, nil, 0, err
 		}
 
+		priority = ctx.Priority()
 		msCache.Write()
 		anteEvents = events.ToABCIEvents()
 	}
@@ -687,19 +689,33 @@ func (app *BaseApp) runTx(mode runTxMode, txBytes []byte) (gInfo sdk.GasInfo, re
 	// and we're in DeliverTx. Note, runMsgs will never return a reference to a
 	// Result if any single message fails or does not have a registered Handler.
 	result, err = app.runMsgs(runMsgCtx, msgs, mode)
-	if err == nil && mode == runTxModeDeliver {
-		// When block gas exceeds, it'll panic and won't commit the cached store.
-		consumeBlockGas()
+	if err == nil {
+		// Run optional postHandlers.
+		//
+		// Note: If the postHandler fails, we also revert the runMsgs state.
+		if app.postHandler != nil {
+			newCtx, err := app.postHandler(runMsgCtx, tx, mode == runTxModeSimulate)
+			if err != nil {
+				return gInfo, nil, nil, priority, err
+			}
 
-		msCache.Write()
+			result.Events = append(result.Events, newCtx.EventManager().ABCIEvents()...)
+		}
 
-		if len(anteEvents) > 0 {
-			// append the events in the order of occurrence
-			result.Events = append(anteEvents, result.Events...)
+		if mode == runTxModeDeliver {
+			// When block gas exceeds, it'll panic and won't commit the cached store.
+			consumeBlockGas()
+
+			msCache.Write()
+
+			if len(anteEvents) > 0 {
+				// append the events in the order of occurrence
+				result.Events = append(anteEvents, result.Events...)
+			}
 		}
 	}
 
-	return gInfo, result, anteEvents, err
+	return gInfo, result, anteEvents, priority, err
 }
 
 // runMsgs iterates through a list of messages and executes them with the provided

baseapp/baseapp_test.go

@@ -36,6 +36,10 @@ import (
 var (
 	capKey1 = sdk.NewKVStoreKey("key1")
 	capKey2 = sdk.NewKVStoreKey("key2")
+
+	// testTxPriority is the CheckTx priority that we set in the test
+	// antehandler.
+	testTxPriority = int64(42)
 )
 
 type paramStore struct {
@@ -826,6 +830,8 @@ func anteHandlerTxTest(t *testing.T, capKey storetypes.StoreKey, storeKey []byte
 			counterEvent("ante_handler", txTest.Counter),
 		)
 
+		ctx = ctx.WithPriority(testTxPriority)
+
 		return ctx, nil
 	}
 }
@@ -933,6 +939,7 @@ func TestCheckTx(t *testing.T) {
 		txBytes, err := codec.Marshal(tx)
 		require.NoError(t, err)
 		r := app.CheckTx(abci.RequestCheckTx{Tx: txBytes})
+		require.Equal(t, testTxPriority, r.Priority)
 		require.Empty(t, r.GetEvents())
 		require.True(t, r.IsOK(), fmt.Sprintf("%v", r))
 	}

baseapp/options.go

@@ -153,6 +153,14 @@ func (app *BaseApp) SetAnteHandler(ah sdk.AnteHandler) {
 	app.anteHandler = ah
 }
 
+func (app *BaseApp) SetPostHandler(ph sdk.AnteHandler) {
+	if app.sealed {
+		panic("SetPostHandler() on sealed BaseApp")
+	}
+
+	app.postHandler = ph
+}
+
 func (app *BaseApp) SetAddrPeerFilter(pf sdk.PeerFilter) {
 	if app.sealed {
 		panic("SetAddrPeerFilter() on sealed BaseApp")

baseapp/test_helpers.go

@@ -16,13 +16,13 @@ func (app *BaseApp) SimCheck(txEncoder sdk.TxEncoder, tx sdk.Tx) (sdk.GasInfo, *
 	if err != nil {
 		return sdk.GasInfo{}, nil, sdkerrors.Wrapf(sdkerrors.ErrInvalidRequest, "%s", err)
 	}
-	gasInfo, result, _, err := app.runTx(runTxModeCheck, bz)
+	gasInfo, result, _, _, err := app.runTx(runTxModeCheck, bz)
 	return gasInfo, result, err
 }
 
 // Simulate executes a tx in simulate mode to get result and gas info.
 func (app *BaseApp) Simulate(txBytes []byte) (sdk.GasInfo, *sdk.Result, error) {
-	gasInfo, result, _, err := app.runTx(runTxModeSimulate, txBytes)
+	gasInfo, result, _, _, err := app.runTx(runTxModeSimulate, txBytes)
 	return gasInfo, result, err
 }
 
@@ -32,7 +32,7 @@ func (app *BaseApp) SimDeliver(txEncoder sdk.TxEncoder, tx sdk.Tx) (sdk.GasInfo,
 	if err != nil {
 		return sdk.GasInfo{}, nil, sdkerrors.Wrapf(sdkerrors.ErrInvalidRequest, "%s", err)
 	}
-	gasInfo, result, _, err := app.runTx(runTxModeDeliver, bz)
+	gasInfo, result, _, _, err := app.runTx(runTxModeDeliver, bz)
 	return gasInfo, result, err
 }
 

simapp/app.go

@@ -34,6 +34,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/auth/ante"
 	authkeeper "github.com/cosmos/cosmos-sdk/x/auth/keeper"
+	"github.com/cosmos/cosmos-sdk/x/auth/posthandler"
 	authsims "github.com/cosmos/cosmos-sdk/x/auth/simulation"
 	authtx "github.com/cosmos/cosmos-sdk/x/auth/tx"
 	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
@@ -443,6 +444,27 @@ func NewSimApp(
 	app.SetBeginBlocker(app.BeginBlocker)
 	app.SetEndBlocker(app.EndBlocker)
 	app.setAnteHandler(encodingConfig.TxConfig, cast.ToStringSlice(appOpts.Get(server.FlagIndexEvents)))
+	// In v0.46, the SDK introduces _postHandlers_. PostHandlers are like
+	// antehandlers, but are run _after_ the `runMsgs` execution. They are also
+	// defined as a chain, and have the same signature as antehandlers.
+	//
+	// In baseapp, postHandlers are run in the same store branch as `runMsgs`,
+	// meaning that both `runMsgs` and `postHandler` state will be committed if
+	// both are successful, and both will be reverted if any of the two fails.
+	//
+	// The SDK exposes a default postHandlers chain, which comprises of only
+	// one decorator: the Transaction Tips decorator. However, some chains do
+	// not need it by default, so the following line is commented out. You can
+	// uncomment it to include the tips decorator, or define your own
+	// postHandler chain. To read more about tips:
+	// https://docs.cosmos.network/main/core/tips.html
+	//
+	// Please note that changing any of the anteHandler or postHandler chain is
+	// likely to be a state-machine breaking change, which needs a coordinated
+	// upgrade.
+	//
+	// Uncomment to enable postHandlers:
+	// app.setPostHandler()
 
 	if loadLatest {
 		if err := app.LoadLatestVersion(); err != nil {
@@ -475,6 +497,19 @@ func (app *SimApp) setAnteHandler(txConfig client.TxConfig, indexEventsStr []str
 	app.SetAnteHandler(anteHandler)
 }
 
+func (app *SimApp) setPostHandler() {
+	postHandler, err := posthandler.NewPostHandler(
+		posthandler.HandlerOptions{
+			BankKeeper: app.BankKeeper,
+		},
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	app.SetPostHandler(postHandler)
+}
+
 // Name returns the name of the App
 func (app *SimApp) Name() string { return app.BaseApp.Name() }
 

types/context.go

@@ -38,6 +38,7 @@ type Context struct {
 	minGasPrice   DecCoins
 	consParams    *tmproto.ConsensusParams
 	eventManager  *EventManager
+	priority      int64 // The tx priority, only relevant in CheckTx
 }
 
 // Proposed rename, not done to avoid API breakage
@@ -58,6 +59,7 @@ func (c Context) IsCheckTx() bool             { return c.checkTx }
 func (c Context) IsReCheckTx() bool           { return c.recheckTx }
 func (c Context) MinGasPrices() DecCoins      { return c.minGasPrice }
 func (c Context) EventManager() *EventManager { return c.eventManager }
+func (c Context) Priority() int64             { return c.priority }
 
 // clone the header before returning
 func (c Context) BlockHeader() tmproto.Header {
@@ -226,6 +228,12 @@ func (c Context) WithEventManager(em *EventManager) Context {
 	return c
 }
 
+// WithEventManager returns a Context with an updated tx priority
+func (c Context) WithPriority(p int64) Context {
+	c.priority = p
+	return c
+}
+
 // TODO: remove???
 func (c Context) IsZero() bool {
 	return c.ms == nil

x/auth/ante/ante.go

@@ -10,11 +10,13 @@ import (
 
 // HandlerOptions are the options required for constructing a default SDK AnteHandler.
 type HandlerOptions struct {
-	AccountKeeper   AccountKeeper
-	BankKeeper      types.BankKeeper
-	FeegrantKeeper  FeegrantKeeper
-	SignModeHandler authsigning.SignModeHandler
-	SigGasConsumer  func(meter sdk.GasMeter, sig signing.SignatureV2, params types.Params) error
+	AccountKeeper          AccountKeeper
+	BankKeeper             types.BankKeeper
+	ExtensionOptionChecker ExtensionOptionChecker
+	FeegrantKeeper         FeegrantKeeper
+	SignModeHandler        authsigning.SignModeHandler
+	SigGasConsumer         func(meter sdk.GasMeter, sig signing.SignatureV2, params types.Params) error
+	TxFeeChecker           TxFeeChecker
 }
 
 // NewAnteHandler returns an AnteHandler that checks and increments sequence
@@ -33,23 +35,17 @@ func NewAnteHandler(options HandlerOptions) (sdk.AnteHandler, error) {
 		return nil, sdkerrors.Wrap(sdkerrors.ErrLogic, "sign mode handler is required for ante builder")
 	}
 
-	var sigGasConsumer = options.SigGasConsumer
-	if sigGasConsumer == nil {
-		sigGasConsumer = DefaultSigVerificationGasConsumer
-	}
-
 	anteDecorators := []sdk.AnteDecorator{
 		NewSetUpContextDecorator(), // outermost AnteDecorator. SetUpContext must be called first
-		NewRejectExtensionOptionsDecorator(),
-		NewMempoolFeeDecorator(),
+		NewExtensionOptionsDecorator(options.ExtensionOptionChecker),
 		NewValidateBasicDecorator(),
 		NewTxTimeoutHeightDecorator(),
 		NewValidateMemoDecorator(options.AccountKeeper),
 		NewConsumeGasForTxSizeDecorator(options.AccountKeeper),
-		NewDeductFeeDecorator(options.AccountKeeper, options.BankKeeper, options.FeegrantKeeper),
+		NewDeductFeeDecorator(options.AccountKeeper, options.BankKeeper, options.FeegrantKeeper, options.TxFeeChecker),
 		NewSetPubKeyDecorator(options.AccountKeeper), // SetPubKeyDecorator must be called before all signature verification decorators
 		NewValidateSigCountDecorator(options.AccountKeeper),
-		NewSigGasConsumeDecorator(options.AccountKeeper, sigGasConsumer),
+		NewSigGasConsumeDecorator(options.AccountKeeper, options.SigGasConsumer),
 		NewSigVerificationDecorator(options.AccountKeeper, options.SignModeHandler),
 		NewIncrementSequenceDecorator(options.AccountKeeper),
 	}